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Huang YC, Liu CJ, Lu ZH, Huang HS. Long-Term Sodium Deficiency Reduces Sodium Excretion but Impairs Renal Function and Increases Stone Formation in Hyperoxaluric Calcium Oxalate Rats. Int J Mol Sci 2024; 25:3942. [PMID: 38612752 PMCID: PMC11011831 DOI: 10.3390/ijms25073942] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2024] [Revised: 03/19/2024] [Accepted: 03/25/2024] [Indexed: 04/14/2024] Open
Abstract
Excessive sodium intake is associated with nephrolithiasis, but the impact of sodium-deficient (SD) diets is unknown. Hence, we investigated the effects of short- and long-term SD diets on the expression of renal aquaporins and sodium transporters, and thus calcium oxalate (CaOx) crystal formation in hyperoxaluria rats. In a short-term sodium balance study, six male rats received drinking water and six received 0.75% ethylene glycol (EG) to induce hyperoxaluria. After a 30-day period of feeding on normal chow, both groups were treated with a normal-sodium diet for 5 days, followed by a sodium-free diet for the next 5 days. In a long-term SD study (42 days), four groups, induced with EG or not, were treated with normal-sodium water and sodium-free drinking water, alternately. Short-term sodium restriction in EG rats reversed the daily positive sodium balance, but progressively caused a negative cumulative water balance. In the long-term study, the abundant levels of of Na/H exchanger, thiazide-sensitive Na-Cl cotransporter, Na-K-ATPase, and aquaporins-1 from SD + EG rats were markedly reduced, corresponding to a decrease in Uosm, as compared to SD rats. Increased urine calcium, AP(CaOx)index, and renal CaOx deposition were also noted in SD + EG rats. Although the SD treatment reduced sodium excretion, it also increased urinary calcium and impaired renal function, ultimately causing the formation of more CaOx crystals.
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Affiliation(s)
| | | | | | - Ho-Shiang Huang
- Department of Urology, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan 704302, Taiwan; (Y.-C.H.); (C.-J.L.); (Z.-H.L.)
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2
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Gámez-Arjona F, Park HJ, García E, Aman R, Villalta I, Raddatz N, Carranco R, Ali A, Ali Z, Zareen S, De Luca A, Leidi EO, Daniel-Mozo M, Xu ZY, Albert A, Kim WY, Pardo JM, Sánchez-Rodriguez C, Yun DJ, Quintero FJ. Inverse regulation of SOS1 and HKT1 protein localization and stability by SOS3/CBL4 in Arabidopsis thaliana. Proc Natl Acad Sci U S A 2024; 121:e2320657121. [PMID: 38386704 PMCID: PMC10907282 DOI: 10.1073/pnas.2320657121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Accepted: 01/12/2024] [Indexed: 02/24/2024] Open
Abstract
To control net sodium (Na+) uptake, Arabidopsis plants utilize the plasma membrane (PM) Na+/H+ antiporter SOS1 to achieve Na+ efflux at the root and Na+ loading into the xylem, and the channel-like HKT1;1 protein that mediates the reverse flux of Na+ unloading off the xylem. Together, these opposing transport systems govern the partition of Na+ within the plant yet they must be finely co-regulated to prevent a futile cycle of xylem loading and unloading. Here, we show that the Arabidopsis SOS3 protein acts as the molecular switch governing these Na+ fluxes by favoring the recruitment of SOS1 to the PM and its subsequent activation by the SOS2/SOS3 kinase complex under salt stress, while commanding HKT1;1 protein degradation upon acute sodic stress. SOS3 achieves this role by direct and SOS2-independent binding to previously unrecognized functional domains of SOS1 and HKT1;1. These results indicate that roots first retain moderate amounts of salts to facilitate osmoregulation, yet when sodicity exceeds a set point, SOS3-dependent HKT1;1 degradation switches the balance toward Na+ export out of the root. Thus, SOS3 functionally links and co-regulates the two major Na+ transport systems operating in vascular plants controlling plant tolerance to salinity.
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Affiliation(s)
- Francisco Gámez-Arjona
- Institute of Plant Biochemistry and Photosynthesis, Consejo Superior de Investigaciones Cientificas and University of Seville, Seville41092, Spain
- Department of Biology, ETH Zurich, Zurich8092, Switzerland
| | - Hee Jin Park
- Department of Biomedical Science and Engineering, Konkuk University, Seoul05029, South Korea
- Department of Biological Sciences, Chonnam National University, Gwangju61186, Korea
| | - Elena García
- Institute of Plant Biochemistry and Photosynthesis, Consejo Superior de Investigaciones Cientificas and University of Seville, Seville41092, Spain
| | - Rashid Aman
- Laboratory for Genome Engineering and Synthetic Biology, King Abdullah University of Science and Technology, Thuwal23955-6900, Saudi Arabia
| | - Irene Villalta
- Institut de Recherche sur la Biologie de l’Insecte, Université de Tours, Tours37200, France
| | - Natalia Raddatz
- Institute of Plant Biochemistry and Photosynthesis, Consejo Superior de Investigaciones Cientificas and University of Seville, Seville41092, Spain
| | - Raul Carranco
- Institute of Plant Biochemistry and Photosynthesis, Consejo Superior de Investigaciones Cientificas and University of Seville, Seville41092, Spain
| | - Akhtar Ali
- Department of Biomedical Science and Engineering, Konkuk University, Seoul05029, South Korea
| | - Zahir Ali
- Laboratory for Genome Engineering and Synthetic Biology, King Abdullah University of Science and Technology, Thuwal23955-6900, Saudi Arabia
| | - Shah Zareen
- Department of Biomedical Science and Engineering, Konkuk University, Seoul05029, South Korea
| | - Anna De Luca
- Institute of Plant Biochemistry and Photosynthesis, Consejo Superior de Investigaciones Cientificas and University of Seville, Seville41092, Spain
| | - Eduardo O. Leidi
- Instituto de Recursos Naturales y Agrobiología, Consejo Superior de Investigaciones Cientificas, Seville41012, Spain
| | - Miguel Daniel-Mozo
- Instituto de Química Física Blas Cabrera, Consejo Superior de Investigaciones Científicas, Madrid28006, Spain
| | - Zheng-Yi Xu
- Key Laboratory of Molecular Epigenetics, Northeast Normal University, Changchun130024, China
| | - Armando Albert
- Instituto de Química Física Blas Cabrera, Consejo Superior de Investigaciones Científicas, Madrid28006, Spain
| | - Woe-Yeon Kim
- Division of Applied Life Science (BK21 Program), Research Institute of Life Sciences, Gyeongsang National University, Jinju660-701, South Korea
| | - Jose M. Pardo
- Institute of Plant Biochemistry and Photosynthesis, Consejo Superior de Investigaciones Cientificas and University of Seville, Seville41092, Spain
| | - Clara Sánchez-Rodriguez
- Department of Biology, ETH Zurich, Zurich8092, Switzerland
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid–Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (CSIC), Pozuelo de Alarcón28223, Spain
| | - Dae-Jin Yun
- Department of Biomedical Science and Engineering, Konkuk University, Seoul05029, South Korea
| | - Francisco J. Quintero
- Institute of Plant Biochemistry and Photosynthesis, Consejo Superior de Investigaciones Cientificas and University of Seville, Seville41092, Spain
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3
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Sato Y, Hashimoto T, Kato K, Okamura A, Hasegawa K, Shinone T, Tanaka Y, Tanaka Y, Tsukazaki T, Tsukamoto T, Demura M, Yao M, Kikukawa T. Multistep conformational changes leading to the gate opening of light-driven sodium pump rhodopsin. J Biol Chem 2023; 299:105393. [PMID: 37890784 PMCID: PMC10679507 DOI: 10.1016/j.jbc.2023.105393] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2023] [Revised: 10/12/2023] [Accepted: 10/19/2023] [Indexed: 10/29/2023] Open
Abstract
Membrane transport proteins require a gating mechanism that opens and closes the substrate transport pathway to carry out unidirectional transport. The "gating" involves large conformational changes and is achieved via multistep reactions. However, these elementary steps have not been clarified for most transporters due to the difficulty of detecting the individual steps. Here, we propose these steps for the gate opening of the bacterial Na+ pump rhodopsin, which outwardly pumps Na+ upon illumination. We herein solved an asymmetric dimer structure of Na+ pump rhodopsin from the bacterium Indibacter alkaliphilus. In one protomer, the Arg108 sidechain is oriented toward the protein center and appears to block a Na+ release pathway to the extracellular (EC) medium. In the other protomer, however, this sidechain swings to the EC side and then opens the release pathway. Assuming that the latter protomer mimics the Na+-releasing intermediate, we examined the mechanism for the swing motion of the Arg108 sidechain. On the EC surface of the first protomer, there is a characteristic cluster consisting of Glu10, Glu159, and Arg242 residues connecting three helices. In contrast, this cluster is disrupted in the second protomer. Our experimental results suggested that this disruption is a key process. The cluster disruption induces the outward movement of the Glu159-Arg242 pair and simultaneously rotates the seventh transmembrane helix. This rotation resultantly opens a space for the swing motion of the Arg108 sidechain. Thus, cluster disruption might occur during the photoreaction and then trigger sequential conformation changes leading to the gate-open state.
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Affiliation(s)
- Yukino Sato
- Graduate School of Life Science, Hokkaido University, Sapporo, Japan
| | - Tsubasa Hashimoto
- Graduate School of Life Science, Hokkaido University, Sapporo, Japan
| | - Koji Kato
- Research Institute for Interdisciplinary Science, Okayama University, Okayama, Japan
| | - Akiko Okamura
- Graduate School of Life Science, Hokkaido University, Sapporo, Japan
| | - Kaito Hasegawa
- Graduate School of Life Science, Hokkaido University, Sapporo, Japan
| | - Tsukasa Shinone
- Graduate School of Life Science, Hokkaido University, Sapporo, Japan
| | - Yoshikazu Tanaka
- Graduate School of Life Sciences, Tohoku University, Sendai, Japan
| | - Yoshiki Tanaka
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Nara, Japan
| | - Tomoya Tsukazaki
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Nara, Japan
| | - Takashi Tsukamoto
- Graduate School of Life Science, Hokkaido University, Sapporo, Japan; Faculty of Advanced Life Science, Hokkaido University, Sapporo, Japan
| | - Makoto Demura
- Graduate School of Life Science, Hokkaido University, Sapporo, Japan; Faculty of Advanced Life Science, Hokkaido University, Sapporo, Japan
| | - Min Yao
- Graduate School of Life Science, Hokkaido University, Sapporo, Japan; Faculty of Advanced Life Science, Hokkaido University, Sapporo, Japan
| | - Takashi Kikukawa
- Graduate School of Life Science, Hokkaido University, Sapporo, Japan; Faculty of Advanced Life Science, Hokkaido University, Sapporo, Japan.
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Liu Y, Peng X, Ma A, Liu W, Liu B, Yun DJ, Xu ZY. Type-B response regulator OsRR22 forms a transcriptional activation complex with OsSLR1 to modulate OsHKT2;1 expression in rice. Sci China Life Sci 2023; 66:2922-2934. [PMID: 37924467 DOI: 10.1007/s11427-023-2464-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Accepted: 10/10/2023] [Indexed: 11/06/2023]
Abstract
Soil salinity severely limits crop yields and quality. Plants have evolved several strategies to mitigate the adverse effects of salinity, including redistribution and compartmentalization of toxic ions using ion-specific transporters. However, the mechanisms underlying the regulation of these ion transporters have not been fully elucidated. Loss-of-function mutants of OsHKT2;1, which is involved in sodium uptake, exhibit strong salt stress-resistant phenotypes. In this study, OsHKT2;1 was identified as a transcriptional target of the type-B response regulator OsRR22. Loss-of-function osrr22 mutants showed resilience to salt stress, and OsRR22-overexpression plants were sensitive to salt stress. OsRR22 was found to activate the expression of OsHKT2;1 by directly binding to the promoter region of OsHKT2;1 via a consensus cis-element of type-B response regulators. Moreover, rice DELLA protein OsSLR1 directly interacted with OsRR22 and functioned as a transcriptional co-activator. This study has uncovered a novel transcriptional regulatory mechanism by which a type-B response regulator controls sodium transport under salinity stress.
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Affiliation(s)
- Yutong Liu
- Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), Northeast Normal University, Changchun, 130024, China
| | - Xiaoyuan Peng
- Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), Northeast Normal University, Changchun, 130024, China
| | - Ao Ma
- Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), Northeast Normal University, Changchun, 130024, China
| | - Wenxin Liu
- Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), Northeast Normal University, Changchun, 130024, China
| | - Bao Liu
- Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), Northeast Normal University, Changchun, 130024, China
| | - Dae-Jin Yun
- Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), Northeast Normal University, Changchun, 130024, China
- Department of Biomedical Science and Engineering, Konkuk University, Seoul, 05029, Republic of Korea
| | - Zheng-Yi Xu
- Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), Northeast Normal University, Changchun, 130024, China.
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5
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Cabral-Costa JV, Vicente-Gutiérrez C, Agulla J, Lapresa R, Elrod JW, Almeida Á, Bolaños JP, Kowaltowski AJ. Mitochondrial sodium/calcium exchanger NCLX regulates glycolysis in astrocytes, impacting on cognitive performance. J Neurochem 2023; 165:521-535. [PMID: 36563047 PMCID: PMC10478152 DOI: 10.1111/jnc.15745] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Revised: 12/11/2022] [Accepted: 12/12/2022] [Indexed: 12/24/2022]
Abstract
Intracellular Ca2+ concentrations are strictly controlled by plasma membrane transporters, the endoplasmic reticulum, and mitochondria, in which Ca2+ uptake is mediated by the mitochondrial calcium uniporter complex (MCUc), while efflux occurs mainly through the mitochondrial Na+ /Ca2+ exchanger (NCLX). RNAseq database repository searches led us to identify the Nclx transcript as highly enriched in astrocytes when compared with neurons. To assess the role of NCLX in mouse primary culture astrocytes, we inhibited its function both pharmacologically or genetically. This resulted in re-shaping of cytosolic Ca2+ signaling and a metabolic shift that increased glycolytic flux and lactate secretion in a Ca2+ -dependent manner. Interestingly, in vivo genetic deletion of NCLX in hippocampal astrocytes improved cognitive performance in behavioral tasks, whereas hippocampal neuron-specific deletion of NCLX impaired cognitive performance. These results unveil a role for NCLX as a novel modulator of astrocytic glucose metabolism, impacting on cognition.
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Affiliation(s)
- João Victor Cabral-Costa
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
- Institute of Functional Biology and Genomics, University of Salamanca-CSIC, Salamanca, Spain
| | - Carlos Vicente-Gutiérrez
- Institute of Functional Biology and Genomics, University of Salamanca-CSIC, Salamanca, Spain
- Centro de Investigación Biomédica en Red Sobre Fragilidad y Envejecimiento Saludable (CIBERFES), Instituto de Salud Carlos III, Madrid, Spain
- Institute of Biomedical Research of Salamanca, University Hospital of Salamanca, University of Salamanca-CSIC, Salamanca, Spain
| | - Jesús Agulla
- Institute of Functional Biology and Genomics, University of Salamanca-CSIC, Salamanca, Spain
- Institute of Biomedical Research of Salamanca, University Hospital of Salamanca, University of Salamanca-CSIC, Salamanca, Spain
| | - Rebeca Lapresa
- Institute of Functional Biology and Genomics, University of Salamanca-CSIC, Salamanca, Spain
- Institute of Biomedical Research of Salamanca, University Hospital of Salamanca, University of Salamanca-CSIC, Salamanca, Spain
| | - John W. Elrod
- Center for Translational Medicine, Lewis Katz School of Medicine at Temple University, Philadelphia, Pennsylvania, USA
| | - Ángeles Almeida
- Institute of Functional Biology and Genomics, University of Salamanca-CSIC, Salamanca, Spain
- Institute of Biomedical Research of Salamanca, University Hospital of Salamanca, University of Salamanca-CSIC, Salamanca, Spain
| | - Juan P. Bolaños
- Institute of Functional Biology and Genomics, University of Salamanca-CSIC, Salamanca, Spain
- Centro de Investigación Biomédica en Red Sobre Fragilidad y Envejecimiento Saludable (CIBERFES), Instituto de Salud Carlos III, Madrid, Spain
- Institute of Biomedical Research of Salamanca, University Hospital of Salamanca, University of Salamanca-CSIC, Salamanca, Spain
| | - Alicia J. Kowaltowski
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
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6
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Mukherji ST, Brambilla L, Stuart KB, Mayes I, Kutz LC, Chen Y, Barbosa LA, Elmadbouh I, McDermott JP, Haller ST, Romero MF, Soleimani M, Liu J, Shapiro JI, Blanco GV, Xie Z, Pierre SV. Na/K-ATPase signaling tonically inhibits sodium reabsorption in the renal proximal tubule. FASEB J 2023; 37:e22835. [PMID: 36856735 PMCID: PMC10028530 DOI: 10.1096/fj.202200785rr] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Revised: 02/08/2023] [Accepted: 02/10/2023] [Indexed: 03/02/2023]
Abstract
Through its classic ATP-dependent ion-pumping function, basolateral Na/K-ATPase (NKA) generates the Na+ gradient that drives apical Na+ reabsorption in the renal proximal tubule (RPT), primarily through the Na+ /H+ exchanger (NHE3). Accordingly, activation of NKA-mediated ion transport decreases natriuresis through activation of basolateral (NKA) and apical (NHE3) Na+ reabsorption. In contrast, activation of the more recently discovered NKA signaling function triggers cellular redistribution of RPT NKA and NHE3 and decreases Na+ reabsorption. We used gene targeting to test the respective contributions of NKA signaling and ion pumping to the overall regulation of RPT Na+ reabsorption. Knockdown of RPT NKA in cells and mice increased membrane NHE3 and Na+ /HCO3 - cotransporter (NBCe1A). Urine output and absolute Na+ excretion decreased by 65%, driven by increased RPT Na+ reabsorption (as indicated by decreased lithium clearance and unchanged glomerular filtration rate), and accompanied by elevated blood pressure. This hyper reabsorptive phenotype was rescued upon crossing with RPT NHE3-/- mice, confirming the importance of NKA/NHE3 coupling. Hence, NKA signaling exerts a tonic inhibition on Na+ reabsorption by regulating key apical and basolateral Na+ transporters. This action, lifted upon NKA genetic suppression, tonically counteracts NKA's ATP-driven function of basolateral Na+ reabsorption. Strikingly, NKA signaling is not only physiologically relevant but it also appears to be functionally dominant over NKA ion pumping in the control of RPT reabsorption.
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Affiliation(s)
- Shreya T. Mukherji
- Marshall Institute for Interdisciplinary Research, Marshall University, Huntington, WV
| | - Luca Brambilla
- Marshall Institute for Interdisciplinary Research, Marshall University, Huntington, WV
| | - Kailey B. Stuart
- Marshall Institute for Interdisciplinary Research, Marshall University, Huntington, WV
| | - Isabella Mayes
- Marshall Institute for Interdisciplinary Research, Marshall University, Huntington, WV
| | - Laura C. Kutz
- Marshall Institute for Interdisciplinary Research, Marshall University, Huntington, WV
| | - Yiliang Chen
- Department of Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin
- Blood Research Institute, Versiti, WI
| | - Leandro A Barbosa
- Marshall Institute for Interdisciplinary Research, Marshall University, Huntington, WV
- Universidade Federal de São João del-Rei, Campus Centro-Oeste Dona Lindu, Divinópolis, MG, Brazil
| | - Ibrahim Elmadbouh
- Marshall Institute for Interdisciplinary Research, Marshall University, Huntington, WV
| | - Jeff P. McDermott
- Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, KS
| | - Steven T. Haller
- Department of Medicine, University of Toledo College of Medicine and Life Sciences, Toledo, OH
| | - Michael F. Romero
- Physiology & Biomedical Engineering and Nephrology & Hypertension, Mayo Clinic College of Medicine & Science, Rochester, MN
| | - Manoocher Soleimani
- Department of Medicine, The University of New Mexico Health Sciences Center, Albuquerque, NM
| | - Jiang Liu
- Joan C. Edwards School of Medicine, Marshall University, Huntington, WV
| | - Joseph I. Shapiro
- Joan C. Edwards School of Medicine, Marshall University, Huntington, WV
| | - Gustavo V. Blanco
- Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, KS
| | - Zijian Xie
- Marshall Institute for Interdisciplinary Research, Marshall University, Huntington, WV
| | - Sandrine V. Pierre
- Marshall Institute for Interdisciplinary Research, Marshall University, Huntington, WV
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7
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Morita S, Tamba N, Shibasaka M, Sasano S, Kadoike T, Urase Y, Maruyama M, Fukuoka A, Yanai J, Masumura T, Ogihara Y, Satoh S, Tanaka K, Katsuhara M, Nakayama H. In planta evidence that the HAK transporter OsHAK2 is involved in Na+ transport in rice. Biosci Biotechnol Biochem 2023; 87:482-490. [PMID: 36804662 DOI: 10.1093/bbb/zbad020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Accepted: 02/12/2023] [Indexed: 02/23/2023]
Abstract
HAK family transporters primarily function as K+ transporters and play major roles in K+ uptake and translocation in plants, whereas several HAK transporters exhibit Na+ transport activity. OsHAK2, a rice HAK transporter, was shown to mediate Na+ transport in E. coli in a previous study. In this study, we investigated whether OsHAK2 is involved in Na+ transport in the rice plant. Overexpression of OsHAK2 increased Na+ translocation from the roots to the shoots of transgenic rice. It also increased both root and whole-plant Na+ content, and enhanced shoot length under low Na+ and K+ conditions. Meanwhile, OsHAK2 overexpression increased salt sensitivity under a long-term salt stress condition, indicating that OsHAK2 is not involved in salt tolerance, unlike in the case of ZmHAK2 in maize. These results suggest that OsHAK2 is permeable to Na+ and contributes to shoot growth in rice plants under low Na+ and K+ conditions.
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Affiliation(s)
- Shigeto Morita
- Graduate School of Life and Environmental Sciences, Kyoto Prefectural University, Kyoto, Japan.,Biotechnology Research Department, Kyoto Prefectural Agriculture, Forestry and Fisheries Technology Center, Seika, Kyoto, Japan
| | - Natsumi Tamba
- Graduate School of Life and Environmental Sciences, Kyoto Prefectural University, Kyoto, Japan
| | - Mineo Shibasaka
- Institute of Plant Science and resources, Okayama University, Kurashiki, Japan
| | - Shizuka Sasano
- Institute of Plant Science and resources, Okayama University, Kurashiki, Japan
| | - Taiju Kadoike
- Graduate School of Life and Environmental Sciences, Kyoto Prefectural University, Kyoto, Japan
| | - Yasuyo Urase
- Graduate School of Life and Environmental Sciences, Kyoto Prefectural University, Kyoto, Japan
| | - Masamitsu Maruyama
- Graduate School of Life and Environmental Sciences, Kyoto Prefectural University, Kyoto, Japan
| | - Aguri Fukuoka
- Graduate School of Life and Environmental Sciences, Kyoto Prefectural University, Kyoto, Japan
| | - Junta Yanai
- Graduate School of Life and Environmental Sciences, Kyoto Prefectural University, Kyoto, Japan
| | - Takehiro Masumura
- Graduate School of Life and Environmental Sciences, Kyoto Prefectural University, Kyoto, Japan.,Biotechnology Research Department, Kyoto Prefectural Agriculture, Forestry and Fisheries Technology Center, Seika, Kyoto, Japan
| | - Yasunari Ogihara
- Kihara Institute for Biological Research, Yokohama City University, Yokohama, Japan
| | - Shigeru Satoh
- Graduate School of Life and Environmental Sciences, Kyoto Prefectural University, Kyoto, Japan
| | - Kunisuke Tanaka
- Graduate School of Life and Environmental Sciences, Kyoto Prefectural University, Kyoto, Japan
| | - Maki Katsuhara
- Institute of Plant Science and resources, Okayama University, Kurashiki, Japan
| | - Hideki Nakayama
- Graduate School of Fisheries and Environmental Sciences, Nagasaki University, Nagasaki, Japan
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8
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Liu Y, Li M, Yu J, Ma A, Wang J, Yun DJ, Xu ZY. Plasma membrane-localized Hsp40/DNAJ chaperone protein facilitates OsSUVH7-OsBAG4-OsMYB106 transcriptional complex formation for OsHKT1;5 activation. J Integr Plant Biol 2023; 65:265-279. [PMID: 36349953 DOI: 10.1111/jipb.13403] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Accepted: 11/07/2022] [Indexed: 06/16/2023]
Abstract
The salinization of irrigated land affects agricultural productivity. HIGH-AFFINITY POTASSIUM (K+ ) TRANSPORTER 1;5 (OsHKT1;5)-dependent sodium (Na+ ) transport is a key salt tolerance mechanism during rice growth and development. Using a previously generated high-throughput activation tagging-based T-DNA insertion mutant pool, we isolated a mutant exhibiting salt stress-sensitive phenotype, caused by a reduction in OsHKT1;5 transcripts. The salt stress-sensitive phenotype of this mutant results from the loss of function of OsDNAJ15, which encodes plasma membrane-localized heat shock protein 40 (Hsp40). osdnaj15 loss-of-function mutants show decreased plant height, increased leaf angle, and reduced grain number caused by shorter panicle length and fewer branches. On the other h'and, OsDNAJ15-overexpression plants showed salt stress-tolerant phenotypes. Intriguingly, salt stress facilitates the nuclear relocation of OsDNAJ15 so that it can interact with OsBAG4, and OsDNAJ15 and OsBAG4 synergistically facilitate the DNA-binding activity of OsMYB106 to positively regulate the expression of OsHKT1;5. Overall, our results reveal a novel function of plasma membrane-localized Hsp40 protein in modulating, alongside chaperon regulator OsBAG4, transcriptional regulation under salinity stress tolerance.
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Affiliation(s)
- Yutong Liu
- Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), Northeast Normal University, Changchun, 130024, China
| | - Mengting Li
- Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), Northeast Normal University, Changchun, 130024, China
| | - Jinlei Yu
- Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), Northeast Normal University, Changchun, 130024, China
| | - Ao Ma
- Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), Northeast Normal University, Changchun, 130024, China
| | - Jie Wang
- Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), Northeast Normal University, Changchun, 130024, China
| | - Dae-Jin Yun
- Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), Northeast Normal University, Changchun, 130024, China
- Department of Biomedical Science and Engineering, Konkuk University, Seoul, South Korea
| | - Zheng-Yi Xu
- Key Laboratory of Molecular Epigenetics of the Ministry of Education (MOE), Northeast Normal University, Changchun, 130024, China
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Faraj SE, Valsecchi WM, Ferreira-Gomes M, Centeno M, Saint Martin EM, Fedosova NU, Rossi JPFC, Montes MR, Rossi RC. Measurements of Na +-occluded intermediates during the catalytic cycle of the Na +/K +-ATPase provide novel insights into the mechanism of Na + transport. J Biol Chem 2022; 299:102811. [PMID: 36539036 PMCID: PMC9860123 DOI: 10.1016/j.jbc.2022.102811] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Revised: 12/11/2022] [Accepted: 12/12/2022] [Indexed: 12/23/2022] Open
Abstract
The Na+/K+-ATPase is an integral plasma membrane glycoprotein of all animal cells that couples the exchange of intracellular Na+ for extracellular K+ to the hydrolysis of ATP. The asymmetric distribution of Na+ and K+ is essential for cellular life and constitutes the physical basis of a series of fundamental biological phenomena. The pumping mechanism is explained by the Albers-Post model. It involves the presence of gates alternatively exposing Na+/K+-ATPase transport sites to the intracellular and extracellular sides and includes occluded states in which both gates are simultaneously closed. Unlike for K+, information is lacking about Na+-occluded intermediates, as occluded Na+ was only detected in states incapable of performing a catalytic cycle, including two Na+-containing crystallographic structures. The current knowledge is that intracellular Na+ must bind to the transport sites and become occluded upon phosphorylation by ATP to be transported to the extracellular medium. Here, taking advantage of epigallocatechin-3-gallate to instantaneously stabilize native Na+-occluded intermediates, we isolated species with tightly bound Na+ in an enzyme able to perform a catalytic cycle, consistent with a genuine occluded state. We found that Na+ becomes spontaneously occluded in the E1 dephosphorylated form of the Na+/K+-ATPase, exhibiting positive interactions between binding sites. In fact, the addition of ATP does not produce an increase in Na+ occlusion as it would have been expected; on the contrary, occluded Na+ transiently decreases, whereas ATP lasts. These results reveal new properties of E1 intermediates of the Albers-Post model for explaining the Na+ transport pathway.
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Affiliation(s)
- Santiago E. Faraj
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Química Biológica, Buenos Aires, Argentina,Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) – Universidad de Buenos Aires, Instituto de Química y Fisicoquímica Biológicas "Prof. Alejandro C. Paladini" (IQUIFIB), Buenos Aires, Argentina
| | - Wanda M. Valsecchi
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Química Biológica, Buenos Aires, Argentina,Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) – Universidad de Buenos Aires, Instituto de Química y Fisicoquímica Biológicas "Prof. Alejandro C. Paladini" (IQUIFIB), Buenos Aires, Argentina
| | - Mariela Ferreira-Gomes
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Química Biológica, Buenos Aires, Argentina,Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) – Universidad de Buenos Aires, Instituto de Química y Fisicoquímica Biológicas "Prof. Alejandro C. Paladini" (IQUIFIB), Buenos Aires, Argentina
| | - Mercedes Centeno
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Química Biológica, Buenos Aires, Argentina,Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) – Universidad de Buenos Aires, Instituto de Química y Fisicoquímica Biológicas "Prof. Alejandro C. Paladini" (IQUIFIB), Buenos Aires, Argentina
| | - Elina Malén Saint Martin
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Química Biológica, Buenos Aires, Argentina
| | | | - Juan Pablo FC. Rossi
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Química Biológica, Buenos Aires, Argentina,Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) – Universidad de Buenos Aires, Instituto de Química y Fisicoquímica Biológicas "Prof. Alejandro C. Paladini" (IQUIFIB), Buenos Aires, Argentina
| | - Mónica R. Montes
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Química Biológica, Buenos Aires, Argentina,Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) – Universidad de Buenos Aires, Instituto de Química y Fisicoquímica Biológicas "Prof. Alejandro C. Paladini" (IQUIFIB), Buenos Aires, Argentina
| | - Rolando C. Rossi
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Química Biológica, Buenos Aires, Argentina,Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) – Universidad de Buenos Aires, Instituto de Química y Fisicoquímica Biológicas "Prof. Alejandro C. Paladini" (IQUIFIB), Buenos Aires, Argentina,For correspondence: Rolando C. Rossi
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10
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Armando I, Cuevas S, Fan C, Kumar M, Izzi Z, Jose PA, Konkalmatt PR. G Protein-Coupled Receptor 37L1 Modulates Epigenetic Changes in Human Renal Proximal Tubule Cells. Int J Mol Sci 2022; 23:ijms232214456. [PMID: 36430934 PMCID: PMC9698582 DOI: 10.3390/ijms232214456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 10/19/2022] [Accepted: 10/31/2022] [Indexed: 11/23/2022] Open
Abstract
Renal luminal sodium transport is essential for physiological blood pressure control, and abnormalities in this process are strongly implicated in the pathogenesis of essential hypertension. Renal G protein-coupled receptors (GPCRs) are critical for the regulation of the reabsorption of essential nutrients, ions, and water from the glomerular filtrate. Recently, we showed that GPCR 37L1 (GPR37L1) is expressed on the apical membrane of renal proximal tubules (RPT) and regulates luminal sodium transport and blood pressure by modulating the function of the sodium proton exchanger 3 (NHE3). However, little is known about GPR37L1 intracellular signaling. Here, we show that GPR37L1 is localized to the nuclear membrane, in addition to the plasma membrane in human RPT cells. Furthermore, GPR37L1 signals via the PI3K/AKT/mTOR pathway to decrease the expression of DNA (cytosine-5)-methyltransferase 1 (DNMT1) and enhance NHE3 transcription. Overall, we demonstrate the direct role of a nuclear membrane GPCR in the regulation of renal sodium through epigenetic gene regulation.
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11
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Huwer H, Hadizamani Y, Moehrlen U, Stammberger U, Gebhard F, Bally L, Wendel A, Liener UC, Lucas R, Hamacher J. Ex Vivo Pulmonary Oedema after In Vivo Blast-Induced Rat Lung Injury: Time Dependency, Blast Intensity and Beta-2 Adrenergic Receptor Role. Biomedicines 2022; 10. [PMID: 36428498 DOI: 10.3390/biomedicines10112930] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Revised: 11/09/2022] [Accepted: 11/11/2022] [Indexed: 11/16/2022] Open
Abstract
Objective: Current treatments for blast-induced lung injury are limited to supportive procedures including mechanical ventilation. The study aimed to investigate the role of post-trauma-induced oedema generation in the function of time and trauma intensity and the probable role of beta 2-adrenergic receptors (β2-ARs) agonists on pulmonary oedema. The study is conducted using an ex vivo model after an experimental in vivo blast-induced thorax trauma in rats. Methods: Rats were randomised and divided into two groups, blast and sham. The blast group were anaesthetised and exposed to the blast wave (3.16 ± 0.43 bar) at a distance of 3.5 cm from the thorax level. The rats were sacrificed 10 min after the blast, the lungs explanted and treated with terbutaline, formoterol, propranolol or amiloride to assess the involvement of sodium transport. Other groups of rats were exposed to distances of 5 and 7 cm from the thorax to reduce the intensity of the injury. Further, one group of rats was studied after 180 min and one after 360 min after a 3.5 cm blast injury. Sham controls were exposed to identical procedures except for receiving blast overpressure. Results: Lung injury and oedema generation depended on time after injury and injury intensity. Perfusion with amiloride resulted in a further increase in oedema formation as indicated by weight gain (p < 0.001), diminished tidal volume (Tv) (p < 0.001), and increased airway resistance (p < 0.001). Formoterol caused a significant increase in the Tv (p < 0.001) and a significant decrease in the airway resistance (p < 0.01), while the lung weight was not influenced. Trauma-related oedema was significantly reduced by terbutaline in terms of lung weight gain (p < 0.01), Tv (p < 0.001), and airway resistance (p < 0.01) compared to control blast-injured lungs. Terbutaline-induced effects were completely blocked by the β-receptor antagonist propranolol (p < 0.05). Similarly, amiloride, which was added to terbutaline perfusion, reversed terbutaline-induced weight gain reduction (p < 0.05). Conclusions: β2-adrenoceptor stimulation had a beneficial impact by amiloride-dependent sodium and therefore, fluid transport mechanisms on the short-term ex vivo oedema generation in a trauma-induced in vivo lung injury of rats.
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12
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Truong-Bolduc QC, Wang Y, Hooper DC. Role of Staphylococcus aureus Tet38 in Transport of Tetracycline and Its Regulation in a Salt Stress Environment. J Bacteriol 2022;:e0014222. [PMID: 35699453 DOI: 10.1128/jb.00142-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Staphylococcus aureus Tet38 efflux pump has multiple functions, including conferring resistance to tetracycline and other compounds and enabling internalization and survival within epithelial cells. In this study, we evaluated the effects of sodium and potassium on tet38 expression. These monovalent cations are known to play a role in transport by the related S. aureus TetK and B. subtilis TetL transporters. tet38 transcription decreased with increasing sodium concentrations by means of direct repression by the salt stress-dependent KdpD/E regulator. tet38 transcription increased 20-fold and tetracycline minimum inhibitory concentration (MIC) increased 4-fold in a ΔkdpD mutant. KdpE bound specifically to the tet38 promoter. Under extreme salt stress, the survival of S. aureus with intact tet38 was reduced compared to that of a Δtet38 mutant. To study the effect of sodium on Tet38 function, we generated constructs overexpressing tet38 and tetK and introduced them into Escherichia coli TO114, which is deficient in major sodium transporters. Tet38 tetracycline efflux was directly demonstrated in a fluorescence assay, and tetracycline efflux of both Tet38 and TetK was abolished by the protonophore carbonyl cyanide 3-chlorophenylhydrazone (CCCP). In contrast, NaCl inhibited efflux by Tet38 but not TetK, whereas KCl inhibited efflux by TetK but not Tet38. Cell-associated Na increased with heterologous overexpression of Tet38. These data indicate that S. aureus Tet38 is a tetracycline efflux pump regulated by the KdpD/E regulator. Under salt stress, S. aureus adjusted its survival in part by reducing the expression of tet38 through KdpD/E. The mechanisms by which Tet38 is detrimental to salt tolerance in S. aureus and inhibited by sodium remain to be determined. IMPORTANCE This study shows that S. aureus Tet38 is a tetracycline efflux pump regulated by KdpD/E regulator. These findings are the first direct demonstration of Tet38-mediated tetracycline efflux, which had previously been inferred from its ability to confer tetracycline resistance. Under salt stress, S. aureus adjusts its survival in part by reducing the expression of tet38 through KdpD/E. We demonstrated the differences in the respective functions of S. aureus Tet38 and other tetracycline efflux transporters (S. aureus TetK, B. subtilis TetL) regarding their transport of tetracycline and Na+/K+. Notably, sodium selectively reduced tetracycline efflux by Tet38, and potassium selectively reduced tetracycline efflux by TetK. The multiple functions of Tet38 emphasize its importance in bacterial adaptation to and survival in diverse environments.
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13
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Affiliation(s)
- Michael F Romero
- Physiology & Biomedical Engineering, Nephrology & Hypertension, Mayo Clinic College of Medicine and Science, Rochester, MN, 55905, USA
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14
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Shandell MA, Capatina AL, Lawrence SM, Brackenbury WJ, Lagos D. Inhibition of the Na +/K +-ATPase by cardiac glycosides suppresses expression of the IDO1 immune checkpoint in cancer cells by reducing STAT1 activation. J Biol Chem 2022; 298:101707. [PMID: 35150740 PMCID: PMC8902613 DOI: 10.1016/j.jbc.2022.101707] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Revised: 01/27/2022] [Accepted: 01/28/2022] [Indexed: 12/18/2022] Open
Abstract
Despite extensive basic and clinical research on immune checkpoint regulatory pathways, little is known about the effects of the ionic tumor microenvironment on immune checkpoint expression and function. Here we describe a mechanistic link between Na+/K+-ATPase (NKA) inhibition and activity of the immune checkpoint protein indoleamine-pyrrole 2',3'-dioxygenase 1 (IDO1). We found that IDO1 was necessary and sufficient for production of kynurenine, a downstream tryptophan metabolite, in cancer cells. We developed a spectrophotometric assay to screen a library of 31 model ion transport-targeting compounds for potential effects on IDO1 function in A549 lung and MDA-MB-231 breast cancer cells. This revealed that the cardiac glycosides ouabain and digoxin inhibited kynurenine production at concentrations that did not affect cell survival. NKA inhibition by ouabain and digoxin resulted in increased intracellular Na+ levels and downregulation of IDO1 mRNA and protein levels, which was consistent with the reduction in kynurenine levels. Knockdown of ATP1A1, the ɑ1 subunit of the NKA and target of cardiac glycosides, increased Na+ levels to a lesser extent than cardiac glycoside treatment and did not affect IDO1 expression. However, ATP1A1 knockdown significantly enhanced the effect of cardiac glycosides on IDO1 expression and kynurenine production. Mechanistically, we show that cardiac glycoside treatment resulted in curtailing the length of phosphorylation-mediated stabilization of STAT1, a transcriptional regulator of IDO1 expression, an effect enhanced by ATP1A1 knockdown. Our findings reveal cross talk between ionic modulation via cardiac glycosides and immune checkpoint protein expression in cancer cells with broad mechanistic and clinical implications.
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Affiliation(s)
- Mia A Shandell
- Department of Biology, University of York, York, United Kingdom; Hull York Medical School, University of York, York, United Kingdom; York Biomedical Research Institute, University of York, York, United Kingdom
| | - Alina L Capatina
- Department of Biology, University of York, York, United Kingdom; York Biomedical Research Institute, University of York, York, United Kingdom
| | | | - William J Brackenbury
- Department of Biology, University of York, York, United Kingdom; York Biomedical Research Institute, University of York, York, United Kingdom
| | - Dimitris Lagos
- Hull York Medical School, University of York, York, United Kingdom; York Biomedical Research Institute, University of York, York, United Kingdom.
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15
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Swapnasrita S, Carlier A, Layton AT. Sex-Specific Computational Models of Kidney Function in Patients With Diabetes. Front Physiol 2022; 13:741121. [PMID: 35153824 PMCID: PMC8827383 DOI: 10.3389/fphys.2022.741121] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Accepted: 01/04/2022] [Indexed: 12/25/2022] Open
Abstract
The kidney plays an essential role in homeostasis, accomplished through the regulation of pH, electrolytes and fluids, by the building blocks of the kidney, the nephrons. One of the important markers of the proper functioning of a kidney is the glomerular filtration rate. Diabetes is characterized by an enlargement of the glomerular and tubular size of the kidney, affecting the afferent and efferent arteriole resistance and hemodynamics, ultimately leading to chronic kidney disease. We postulate that the diabetes-induced changes in kidney may exhibit significant sex differences as the distribution of renal transporters along the nephron may be markedly different between women and men, as recently shown in rodents. The goals of this study are to (i) analyze how kidney function is altered in male and female patients with diabetes, and (ii) assess the renal effects, in women and men, of an anti-hyperglycemic therapy that inhibits the sodium-glucose cotransporter 2 (SGLT2) in the proximal convoluted tubules. To accomplish these goals, we have developed computational models of kidney function, separate for male and female patients with diabetes. The simulation results indicate that diabetes enhances Na+ transport, especially along the proximal tubules and thick ascending limbs, to similar extents in male and female patients, which can be explained by the diabetes-induced increase in glomerular filtration rate. Additionally, we conducted simulations to study the effects of diabetes and SGLT2 inhibition on solute and water transport along the nephrons. Model simulations also suggest that SGLT2 inhibition raises luminal [Cl–] at the macula densa, twice as much in males as in females, and could indicate activation of the tubuloglomerular feedback signal. By inducing osmotic diuresis in the proximal tubules, SGLT2 inhibition reduces paracellular transport, eventually leading to diuresis and natriuresis. Those effects on urinary excretion are blunted in women, in part due to their higher distal transport capacity.
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Affiliation(s)
- Sangita Swapnasrita
- Department of Cell Biology-Inspired Tissue Engineering, MERLN Institute for Technology-Inspired Regenerative Medicine, Maastricht University, Maastricht, Netherlands
| | - Aurélie Carlier
- Department of Cell Biology-Inspired Tissue Engineering, MERLN Institute for Technology-Inspired Regenerative Medicine, Maastricht University, Maastricht, Netherlands
| | - Anita T Layton
- Department of Applied Mathematics, University of Waterloo, Waterloo, ON, Canada.,Department of Biology, Cheriton School of Computer Science, School of Pharmacology, University of Waterloo, Waterloo, ON, Canada
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16
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Abuslima E, Kanbar A, Raorane ML, Eiche E, Junker BH, Hause B, Riemann M, Nick P. Gain time to adapt: How sorghum acquires tolerance to salinity. Front Plant Sci 2022; 13:1008172. [PMID: 36325549 PMCID: PMC9619063 DOI: 10.3389/fpls.2022.1008172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2022] [Accepted: 09/05/2022] [Indexed: 05/14/2023]
Abstract
Salinity is a global environmental threat to agricultural production and food security around the world. To delineate salt-induced damage from adaption events we analysed a pair of sorghum genotypes which are contrasting in their response to salt stress with respect to physiological, cellular, metabolomic, and transcriptional responses. We find that the salt-tolerant genotype Della can delay the transfer of sodium from the root to the shoot, more swiftly deploy accumulation of proline and antioxidants in the leaves and transfer more sucrose to the root as compared to its susceptible counterpart Razinieh. Instead Razinieh shows metabolic indicators for a higher extent photorespiration under salt stress. Following sodium accumulation by a fluorescent dye in the different regions of the root, we find that Della can sequester sodium in the vacuoles of the distal elongation zone. The timing of the adaptive responses in Della leaves indicates a rapid systemic signal from the roots that is travelling faster than sodium itself. We arrive at a model where resistance and susceptibility are mainly a matter of temporal patterns in signalling.
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Affiliation(s)
- Eman Abuslima
- Molecular Cell Biology, Botanical Institute, Karlsruhe Institute of Technology, Karlsruhe, Germany
- Department of Botany, Faculty of Science, Suez Canal University, Ismailia, Egypt
- *Correspondence: Eman Abuslima,
| | - Adnan Kanbar
- Molecular Cell Biology, Botanical Institute, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Manish L. Raorane
- Institute of Pharmacy, Martin-Luther-University, Halle-Wittenberg, Halle, Germany
| | - Elisabeth Eiche
- Institute of Applied Geosciences, Karlsruhe Institute of Technology, Karlsruhe, Germany
- Laboratory for Environmental and Raw Materials Analysis (LERA), Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Björn H. Junker
- Institute of Pharmacy, Martin-Luther-University, Halle-Wittenberg, Halle, Germany
| | - Bettina Hause
- Cell and Metabolic Biology, Leibniz Institute of Plant Biochemistry (IPB), Halle, Germany
| | - Michael Riemann
- Molecular Cell Biology, Botanical Institute, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Peter Nick
- Molecular Cell Biology, Botanical Institute, Karlsruhe Institute of Technology, Karlsruhe, Germany
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17
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Sassi A, Wang Y, Chassot A, Roth I, Ramakrishnan S, Olivier V, Staub O, Udwan K, Feraille E. Expression of claudin-8 is induced by aldosterone in renal collecting duct principal cells. Am J Physiol Renal Physiol 2021; 321:F645-F655. [PMID: 34605273 DOI: 10.1152/ajprenal.00207.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Fine tuning of Na+ reabsorption takes place along the aldosterone-sensitive distal nephron, which includes the collecting duct (CD), where it is mainly regulated by aldosterone. In the CD, Na+ reabsorption is mediated by the epithelial Na+ channel and Na+ pump (Na+-K+-ATPase). Paracellular ion permeability is mainly dependent on tight junction permeability. Claudin-8 is one of the main tight junction proteins expressed along the aldosterone-sensitive distal nephron. We have previously shown a coupling between transcellular Na+ reabsorption and paracellular Na+ barrier. We hypothesized that aldosterone controls the expression levels of both transcellular Na+ transporters and paracellular claudin-8 in a coordinated manner. Here, we show that aldosterone increased mRNA and protein levels as well as lateral membrane localization of claudin-8 in cultured CD principal cells. The increase in claudin-8 mRNA levels in response to aldosterone was prevented by preincubation with 17-hydroxyprogesterone, a mineralocorticoid receptor antagonist, and by inhibition of transcription with actinomycin D. We also showed that a low-salt diet, which stimulated aldosterone secretion, was associated with increased claudin-8 abundance in the mouse kidney. Reciprocally, mice subjected to a high-salt diet, which inhibits aldosterone secretion, or treated with spironolactone, a mineralocorticoid receptor antagonist, displayed decreased claudin-8 expression. Inhibition of glycogen synthase kinase-3, Lyn, and Abl signaling pathways prevented the effect of aldosterone on claudin-8 mRNA and protein abundance, suggesting that signaling of protein kinases plays a permissive role on the transcriptional activity of the mineralocorticoid receptor. This study shows that signaling via multiple protein kinases working in concert mediates aldosterone-induced claudin-8 expression in the CD.NEW & NOTEWORTHY In this study, we showed that aldosterone modulates claudin-8 expression in cultured collecting duct principal cells and in the mouse kidney. The upregulation of claudin-8 expression in response to aldosterone is dependent on at least glycogen synthase kinase-3, Lyn, and Abl signaling pathways, indicating the participation of multiple protein kinases to the effect of aldosterone.
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Affiliation(s)
- Ali Sassi
- Department of Cellular Physiology and Metabolism, University of Geneva, Geneva, Switzerland.,National Center of Competence in Research "Kidney.ch," Switzerland
| | - Yubao Wang
- Department of Cellular Physiology and Metabolism, University of Geneva, Geneva, Switzerland.,National Center of Competence in Research "Kidney.ch," Switzerland
| | - Alexandra Chassot
- Department of Cellular Physiology and Metabolism, University of Geneva, Geneva, Switzerland.,National Center of Competence in Research "Kidney.ch," Switzerland
| | - Isabelle Roth
- Department of Cellular Physiology and Metabolism, University of Geneva, Geneva, Switzerland
| | - Suresh Ramakrishnan
- Department of Cellular Physiology and Metabolism, University of Geneva, Geneva, Switzerland.,National Center of Competence in Research "Kidney.ch," Switzerland
| | - Valérie Olivier
- Department of Cellular Physiology and Metabolism, University of Geneva, Geneva, Switzerland.,National Center of Competence in Research "Kidney.ch," Switzerland
| | - Olivier Staub
- Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland
| | - Khalil Udwan
- Department of Cellular Physiology and Metabolism, University of Geneva, Geneva, Switzerland
| | - Eric Feraille
- Department of Cellular Physiology and Metabolism, University of Geneva, Geneva, Switzerland.,National Center of Competence in Research "Kidney.ch," Switzerland
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18
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Soares AG, Contreras J, Archer CR, Mironova E, Berdeaux R, Stockand JD, Abd El-Aziz TM. Stimulation of the Epithelial Na + Channel in Renal Principal Cells by Gs-Coupled Designer Receptors Exclusively Activated by Designer Drugs. Front Physiol 2021; 12:725782. [PMID: 34512393 PMCID: PMC8425396 DOI: 10.3389/fphys.2021.725782] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Accepted: 07/28/2021] [Indexed: 11/29/2022] Open
Abstract
The activity of the Epithelial Na+ Channel (ENaC) in renal principal cells (PC) fine-tunes sodium excretion and consequently, affects blood pressure. The Gs-adenylyl cyclase-cAMP signal transduction pathway is believed to play a central role in the normal control of ENaC activity in PCs. The current study quantifies the importance of this signaling pathway to the regulation of ENaC activity in vivo using a knock-in mouse that has conditional expression of Gs-DREADD (designer receptors exclusively activated by designer drugs; GsD) in renal PCs. The GsD mouse also contains a cAMP response element-luciferase reporter transgene for non-invasive bioluminescence monitoring of cAMP signaling. Clozapine N-oxide (CNO) was used to selectively and temporally stimulate GsD. Treatment with CNO significantly increased luciferase bioluminescence in the kidneys of PC-specific GsD but not control mice. CNO also significantly increased the activity of ENaC in principal cells in PC-specific GsD mice compared to untreated knock-in mice and CNO treated littermate controls. The cell permeable cAMP analog, 8-(4-chlorophenylthio)adenosine 3′,5′-cyclic monophosphate, significantly increased the activity and expression in the plasma membrane of recombinant ENaC expressed in CHO and COS-7 cells, respectively. Treatment of PC-specific GsD mice with CNO rapidly and significantly decreased urinary Na+ excretion compared to untreated PC-specific GsD mice and treated littermate controls. This decrease in Na+ excretion in response to CNO in PC-specific GsD mice was similar in magnitude and timing as that induced by the selective vasopressin receptor 2 agonist, desmopressin, in wild type mice. These findings demonstrate for the first time that targeted activation of Gs signaling exclusively in PCs is sufficient to increase ENaC activity and decrease dependent urinary Na+ excretion in live animals.
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Affiliation(s)
- Antonio G Soares
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
| | - Jorge Contreras
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
| | - Crystal R Archer
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
| | - Elena Mironova
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
| | - Rebecca Berdeaux
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, Houston, TX, United States
| | - James D Stockand
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
| | - Tarek Mohamed Abd El-Aziz
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States.,Zoology Department, Faculty of Science, Minia University, Minya, Egypt
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19
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Kryvenko V, Wessendorf M, Tello K, Herold S, Morty RE, Seeger W, Vadász I. Hypercapnia-induces IRE1α-driven Endoplasmic Reticulum-associated Degradation of the Na,K-ATPase β-subunit. Am J Respir Cell Mol Biol 2021; 65:615-629. [PMID: 34192507 DOI: 10.1165/rcmb.2021-0114oc] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Acute respiratory distress syndrome (ARDS) is often associated with elevated levels of CO2 (hypercapnia) and impaired alveolar fluid clearance. Misfolding of the Na,K-ATPase (NKA), a key molecule involved in both alveolar epithelial barrier tightness and in resolution of alveolar edema, in the endoplasmic reticulum (ER) may decrease plasma membrane (PM) abundance of the transporter. Here, we investigated how hypercapnia affects the NKA β-subunit (NKA-β) in the ER. Exposing murine precision-cut lung slices (PCLS) and human alveolar epithelial A549 cells to elevated CO2 levels led to a rapid decrease of NKA-β abundance in the ER and at the cell surface. Knockdown of ER alpha-mannosidase I (MAN1B1) and ER degradation enhancing alpha-mannosidase like protein 1 by siRNA or treatment with the MAN1B1 inhibitor, kifunensine rescued loss of NKA-β in the ER, suggesting ER-associated degradation (ERAD) of the enzyme. Furthermore, hypercapnia activated the unfolded protein response (UPR) by promoting phosphorylation of inositol-requiring enzyme 1α (IRE1α) and treatment with a siRNA against IRE1α prevented the decrease of NKA-β in the ER. Of note, the hypercapnia-induced phosphorylation of IRE1α was triggered by a Ca2+-dependent mechanism. Additionally, inhibition of the inositol trisphosphate receptor decreased phosphorylation levels of IRE1α in PCLS and A549 cells, suggesting that Ca2+ efflux from the ER might be responsible for IRE1α activation and ERAD of NKA-β. In conclusion, here we provide evidence that hypercapnia attenuates maturation of the regulatory subunit of NKA by activating IRE1α and promoting ERAD, which may contribute to impaired alveolar epithelial integrity in patients with ARDS and hypercapnia.
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Affiliation(s)
- Vitalii Kryvenko
- Justus Liebig University, Universities of Giessen and Marburg Lung Center, Member of the German Center for Lung Research, Department of Internal Medicine, Giessen, Germany.,The Cardio-Pulmonary Institute, Giessen, Germany
| | - Miriam Wessendorf
- Justus Liebig University, Universities of Giessen and Marburg Lung Center, Member of the German Center for Lung Research, Department of Internal Medicine, Giessen, Germany
| | - Khodr Tello
- Justus Liebig University, Universities of Giessen and Marburg Lung Center, Member of the German Center for Lung Research, Department of Internal Medicine, Giessen, Germany.,The Cardio-Pulmonary Institute, Giessen, Germany
| | - Susanne Herold
- Justus Liebig University, Universities of Giessen and Marburg Lung Center, Member of the German Center for Lung Research, Department of Internal Medicine, Giessen, Germany.,The Cardio-Pulmonary Institute, Giessen, Germany
| | - Rory E Morty
- Justus Liebig University, Universities of Giessen and Marburg Lung Center, Member of the German Center for Lung Research, Department of Internal Medicine, Giessen, Germany.,The Cardio-Pulmonary Institute, Giessen, Germany.,Max-Planck-Institute for Heart and Lung Research, Department of Lung Development and Remodeling, Bad Nauheim, Germany
| | - Werner Seeger
- Justus Liebig University, Universities of Giessen and Marburg Lung Center, Member of the German Center for Lung Research, Department of Internal Medicine, Giessen, Germany.,The Cardio-Pulmonary Institute, Giessen, Germany.,Max-Planck-Institute for Heart and Lung Research, Department of Lung Development and Remodeling, Bad Nauheim, Germany.,Justus Liebig University, Universities of Giessen and Marburg Lung Center, Member of the German Center for Lung Research, Department of Internal Medicine, Giessen, Germany
| | - István Vadász
- Justus Liebig University, Universities of Giessen and Marburg Lung Center, Member of the German Center for Lung Research, Department of Internal Medicine, Giessen, Germany.,The Cardio-Pulmonary Institute, Giessen, Germany;
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20
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Illarionov A, Lahtvee PJ, Kumar R. Potassium and Sodium Salt Stress Characterization in the Yeasts Saccharomyces cerevisiae, Kluyveromyces marxianus, and Rhodotorula toruloides. Appl Environ Microbiol 2021; 87:e0310020. [PMID: 33893111 DOI: 10.1128/AEM.03100-20] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Biotechnology requires efficient microbial cell factories. The budding yeast Saccharomyces cerevisiae is a vital cell factory, but more diverse cell factories are essential for the sustainable use of natural resources. Here, we benchmarked nonconventional yeasts Kluyveromyces marxianus and Rhodotorula toruloides against S. cerevisiae strains CEN.PK and W303 for their responses to potassium and sodium salt stress. We found an inverse relationship between the maximum growth rate and the median cell volume that was responsive to salt stress. The supplementation of K+ to CEN.PK cultures reduced Na+ toxicity and increased the specific growth rate 4-fold. The higher K+ and Na+ concentrations impaired ethanol and acetate metabolism in CEN.PK and acetate metabolism in W303. In R. toruloides cultures, these salt supplementations induced a trade-off between glucose utilization and cellular aggregate formation. Their combined use increased the beta-carotene yield by 60% compared with that of the reference. Neural network-based image analysis of exponential-phase cultures showed that the vacuole-to-cell volume ratio increased with increased cell volume for W303 and K. marxianus but not for CEN.PK and R. toruloides in response to salt stress. Our results provide insights into common salt stress responses in yeasts and will help design efficient bioprocesses. IMPORTANCE Characterization of microbial cell factories under industrially relevant conditions is crucial for designing efficient bioprocesses. Salt stress, typical in industrial bioprocesses, impinges upon cell volume and affects productivity. This study presents an open-source neural network-based analysis method to evaluate volumetric changes using yeast optical microscopy images. It allows quantification of cell and vacuole volumes relevant to cellular physiology. On applying salt stress in yeasts, we found that the combined use of K+ and Na+ improves the cellular fitness of Saccharomyces cerevisiae strain CEN.PK and increases the beta-carotene productivity in Rhodotorula toruloides, a commercially important antioxidant and a valuable additive in foods.
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21
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Abstract
At the onset of diabetes, the kidney grows large and the glomerular filtration rate becomes abnormally high. These structural and hemodynamics changes affect kidney function and may contribute to the development of chronic kidney disease. The goal of this study is to analyze how kidney function is altered in patients with diabetes and the renal effects of an anti-hyperglyceamic therapy that inhibits the sodium-glucose cotransporter 2 (SGLT2) in the proximal convoluted tubules. To accomplish that goal, we have developed a computational model of kidney function in a patient with diabetes and conducted simulations to study the effects of diabetes and SGLT2 inhibition on solute and water transport along the nephrons. Simulation results indicate that diabetes-induced hyperfiltration and tubular hypertrophy enhances Na+ transport, especially along the proximal tubules and thick ascending limbs. These simulations suggest that SGLT2 inhibition may attenuate glomerular hyperfiltration by limiting Na+-glucose transport, raising luminal [Cl-] at the macula densa, restoring the tubuloglomerular feedback signal, thereby reducing single-nephron glomerular filtration rate.
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Affiliation(s)
- Rui Hu
- Department of Applied Mathematics, University of Waterloo, Waterloo, ON N2L 3G1, Canada;
| | - Anita Layton
- Department of Applied Mathematics, University of Waterloo, Waterloo, ON N2L 3G1, Canada;
- Department of Biology, Cheriton School of Computer Science, and School of Pharmacology, University of Waterloo, Waterloo, ON N2L 3G1, Canada
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22
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Kato T, Tsukamoto T, Demura M, Kikukawa T. Real-time identification of two substrate-binding intermediates for the light-driven sodium pump rhodopsin. J Biol Chem 2021; 296:100792. [PMID: 34019877 PMCID: PMC8219890 DOI: 10.1016/j.jbc.2021.100792] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 05/10/2021] [Accepted: 05/13/2021] [Indexed: 11/29/2022] Open
Abstract
Membrane transport proteins undergo critical conformational changes during substrate uptake and release, as the substrate-binding site is believed to switch its accessibility from one side of the membrane to the other. Thus, at least two substrate-binding intermediates should appear during the process, that is, after uptake and before the release of the substrate. However, this view has not been verified for most transporters because of the difficulty in detecting short-lived intermediates. Here, we report real-time identification of these intermediates for the light-driven outward current-generating Na+-pump rhodopsin. We triggered the transport cycle of Na+-pump rhodopsin using a short laser pulse, and subsequent formation and decay of various intermediates was detected by time-resolved measurements of absorption changes. We used this method to analyze transport reactions and elucidated the sequential formation of the Na+-binding intermediates O1 and O2. Both intermediates exhibited red-shifted absorption spectra and generated transient equilibria with short-wavelength intermediates. The equilibria commonly shifted toward O1 and O2 with increasing Na+ concentration, indicating that Na+ is bound to these intermediates. However, these equilibria were formed independently; O1 reached equilibrium with preceding intermediates, indicating Na+ uptake on the cytoplasmic side. In contrast, O2 reached equilibrium with subsequent intermediates, indicating Na+ release on the extracellular side. Thus, there is an irreversible switch in “accessibility” during the O1 to O2 transition, which could represent one of the key processes governing unidirectional Na+ transport.
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Affiliation(s)
- Tomoya Kato
- Graduate School of Life Science, Hokkaido University, Sapporo, Japan
| | - Takashi Tsukamoto
- Faculty of Advanced Life Science, Hokkaido University, Sapporo, Japan; Global Station for Soft Matter, Global Institution for Collaborative Research and Education, Hokkaido University, Sapporo, Japan
| | - Makoto Demura
- Faculty of Advanced Life Science, Hokkaido University, Sapporo, Japan; Global Station for Soft Matter, Global Institution for Collaborative Research and Education, Hokkaido University, Sapporo, Japan
| | - Takashi Kikukawa
- Faculty of Advanced Life Science, Hokkaido University, Sapporo, Japan; Global Station for Soft Matter, Global Institution for Collaborative Research and Education, Hokkaido University, Sapporo, Japan.
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23
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Tsujimura M, Ishikita H. Identification of intermediate conformations in the photocycle of the light-driven sodium-pumping rhodopsin KR2. J Biol Chem 2021; 296:100459. [PMID: 33639164 DOI: 10.1016/j.jbc.2021.100459] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Revised: 02/21/2021] [Accepted: 02/23/2021] [Indexed: 11/21/2022] Open
Abstract
The light-driven rhodopsin KR2 transports Na+via the M- and O-states. However, the mechanisms by which the retinal regulates Na+ pumping is unknown, in part because KR2 adopts both pentamer and monomer forms in crystal structures and in part because these structures show differences in the protein conformation near the Schiff base, even when they are of the same intermediate state within the photocycle. A particular open question is the nature of the H-bond networks and protonation state in the active site, including Asp116. Here, we analyze the protonation state and the absorption wavelength for each crystal structure, using a quantum mechanical/molecular mechanical approach. In the pentamer ground state, the calculated absorption wavelength reproduces the experimentally measured absorption wavelength (530 nm). The analysis also shows that ionized Asp116 is stabilized by the H-bond donations of both Ser70 and a cluster of water molecules. The absorption wavelength of 400 nm in the M-state can be best reproduced when the two O atoms of Asp116 interact strongly with the Schiff base, as reported in one of the previous monomer ground state structures. The absorption wavelengths calculated for the two Na+-incorporated O-state structures are consistent with the measured absorption wavelength (∼600 nm), which suggests that two conformations represent the O-state. These results may provide a key to designing enhanced tools in optogenetics.
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24
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Riedelsberger J, Miller JK, Valdebenito-Maturana B, Piñeros MA, González W, Dreyer I. Plant HKT Channels: An Updated View on Structure, Function and Gene Regulation. Int J Mol Sci 2021; 22:1892. [PMID: 33672907 DOI: 10.3390/ijms22041892] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 01/29/2021] [Accepted: 02/09/2021] [Indexed: 12/28/2022] Open
Abstract
HKT channels are a plant protein family involved in sodium (Na+) and potassium (K+) uptake and Na+-K+ homeostasis. Some HKTs underlie salt tolerance responses in plants, while others provide a mechanism to cope with short-term K+ shortage by allowing increased Na+ uptake under K+ starvation conditions. HKT channels present a functionally versatile family divided into two classes, mainly based on a sequence polymorphism found in the sequences underlying the selectivity filter of the first pore loop. Physiologically, most class I members function as sodium uniporters, and class II members as Na+/K+ symporters. Nevertheless, even within these two classes, there is a high functional diversity that, to date, cannot be explained at the molecular level. The high complexity is also reflected at the regulatory level. HKT expression is modulated at the level of transcription, translation, and functionality of the protein. Here, we summarize and discuss the structure and conservation of the HKT channel family from algae to angiosperms. We also outline the latest findings on gene expression and the regulation of HKT channels.
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25
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Repetti R, Majumder N, De Oliveira KC, Meth J, Yangchen T, Sharma M, Srivastava T, Rohatgi R. Unilateral Nephrectomy Stimulates ERK and Is Associated With Enhanced Na Transport. Front Physiol 2021; 12:583453. [PMID: 33633581 PMCID: PMC7901926 DOI: 10.3389/fphys.2021.583453] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Accepted: 01/14/2021] [Indexed: 11/13/2022] Open
Abstract
Nephron loss initiates compensatory hemodynamic and cellular effects on the remaining nephrons. Increases in single nephron glomerular filtration rate and tubular flow rate exert higher fluid shear stress (FSS) on tubules. In principal cell (PC) culture models FSS induces ERK, and ERK is implicated in the regulation of transepithelial sodium (Na) transport, as well as, proliferation. Thus, we hypothesize that high tubular flow and FSS mediate ERK activation in the cortical collecting duct (CCD) of solitary kidney which regulates amiloride sensitive Na transport and affects CCD cell number. Immunoblotting of whole kidney protein lysate was performed to determine phospho-ERK (pERK) expression. Next, sham and unilateral nephrectomized mice were stained with anti-pERK antibodies, and dolichos biflorus agglutinin (DBA) to identify PCs with pERK. Murine PCs (mpkCCD) were grown on semi-permeable supports under static, FSS, and FSS with U0126 (a MEK1/2 inhibitor) conditions to measure the effects of FSS and ERK inhibition on amiloride sensitive Na short circuit current (Isc). pERK abundance was greater in kidney lysate of unilateral vs. sham nephrectomies. The total number of cells in CCD and pERK positive PCs increased in nephrectomized mice (9.3 ± 0.4 vs. 6.1 ± 0.2 and 5.1 ± 0.5 vs. 3.6 ± 0.3 cell per CCD nephrectomy vs. sham, respectively, n > 6 per group, p < 0.05). However, Ki67, a marker of proliferation, did not differ by immunoblot or immunohistochemistry in nephrectomy samples at 1 month compared to sham. Next, amiloride sensitive Isc in static mpkCCD cells was 25.3 ± 1.7 μA/cm2 (n = 21), but after exposure to 24 h of FSS the Isc increased to 41.4 ± 2.8 μA/cm2 (n = 22; p < 0.01) and returned to 19.1 ± 2.1 μA/cm2 (n = 18, p < 0.01) upon treatment with U0126. Though FSS did not alter α- or γ-ENaC expression in mpkCCD cells, γ-ENaC was reduced in U0126 treated cells. In conclusion, pERK increases in whole kidney and, specifically, CCD cells after nephrectomy, but pERK was not associated with active proliferation at 1-month post-nephrectomy. In vitro studies suggest high tubular flow induces ERK dependent ENaC Na absorption and may play a critical role in Na balance post-nephrectomy.
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Affiliation(s)
- Robert Repetti
- Northport VA Medical Center, Northport, NY, United States.,School of Medicine, Stony Brook University, Stony Brook, NY, United States
| | - Nomrota Majumder
- School of Medicine, Stony Brook University, Stony Brook, NY, United States
| | | | - Jennifer Meth
- Northport VA Medical Center, Northport, NY, United States
| | - Tenzin Yangchen
- Program in Public Health, School of Medicine, Stony Brook University, Stony Brook, NY, United States
| | - Mukut Sharma
- Kansas City VA Medical Center, Kansas City, MO, United States
| | | | - Rajeev Rohatgi
- Northport VA Medical Center, Northport, NY, United States.,School of Medicine, Stony Brook University, Stony Brook, NY, United States
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26
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Pasricha ND, Smith AJ, Levin MH, Schallhorn JM, Verkman AS. Ocular Surface Potential Difference Measured in Human Subjects to Study Ocular Surface Ion Transport. Transl Vis Sci Technol 2020; 9:20. [PMID: 33117611 PMCID: PMC7571274 DOI: 10.1167/tvst.9.11.20] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Accepted: 09/08/2020] [Indexed: 12/14/2022] Open
Abstract
Purpose The epithelium lining the ocular surface, which includes corneal and conjunctival epithelia, expresses the prosecretory chloride channel cystic fibrosis transmembrane conductance regulator (CFTR) and the proabsorptive epithelial sodium channel (ENaC). Here, methodology was established to measure the millivolt (mV) potential differences at the ocular surface, called ocular surface potential difference (OSPD), in human subjects produced by ion transport. Methods OSPD was measured in human subjects in which a fluid-filled measuring electrode contacted a fluid pool created by eversion of the lateral lower eyelid, with a reference electrode placed subcutaneously in the forearm. Through the use of a high-impedance voltmeter, OSPD was measured continuously over 10 to 15 minutes in response to a series of perfusate fluid exchanges. Results Baseline OSPD (± SEM) in six normal human subjects was -21.3 ± 3.6 mV. OSPD depolarized by 1.7 ± 0.6 mV following the addition of the ENaC inhibitor amiloride, hyperpolarized by 6.8 ± 1.5 mV with a zero chloride solution, and further hyperpolarized by 15.9 ± 1.6 mV following CFTR activation by isoproterenol. The isoproterenol-induced hyperpolarization was absent in two cystic fibrosis subjects lacking functional CFTR. OSPD measurement produced minimal epithelial injury. Conclusions Our results establish the feasibility and safety of OSPD measurement in humans and demonstrate robust CFTR activity, albeit minimal ENaC activity, at the ocular surface. OSPD measurement may be broadly applicable to investigate fluid transport mechanisms and test drug candidates to treat ocular surface disorders. Translational Relevance To the best of our knowledge, this is the first measurement of the electrical potential generated by the ocular surface epithelium in human subjects, offering a new approach to study ocular surface function and health.
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Affiliation(s)
- Neel D Pasricha
- Department of Ophthalmology, University of California San Francisco, San Francisco, CA, USA
| | - Alex J Smith
- Department of Ophthalmology, University of California San Francisco, San Francisco, CA, USA.,Departments of Medicine and Physiology, University of California San Francisco, San Francisco, CA, USA
| | - Marc H Levin
- Department of Ophthalmology, Palo Alto Medical Foundation, Palo Alto, CA, USA
| | - Julie M Schallhorn
- Department of Ophthalmology, University of California San Francisco, San Francisco, CA, USA.,Francis I. Proctor Foundation, University of California San Francisco, San Francisco, CA, USA
| | - Alan S Verkman
- Departments of Medicine and Physiology, University of California San Francisco, San Francisco, CA, USA
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27
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Qiu J, McGaughey SA, Groszmann M, Tyerman SD, Byrt CS. Phosphorylation influences water and ion channel function of AtPIP2;1. Plant Cell Environ 2020; 43:2428-2442. [PMID: 32678928 DOI: 10.1111/pce.13851] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Revised: 07/09/2020] [Accepted: 07/09/2020] [Indexed: 05/24/2023]
Abstract
The phosphorylation state of two serine residues within the C-terminal domain of AtPIP2;1 (S280, S283) regulates its plasma membrane localization in response to salt and osmotic stress. Here, we investigated whether the phosphorylation state of S280 and S283 also influence AtPIP2;1 facilitated water and cation transport. A series of single and double S280 and S283 phosphomimic and phosphonull AtPIP2;1 mutants were tested in heterologous systems. In Xenopus laevis oocytes, phosphomimic mutants AtPIP2;1 S280D, S283D, and S280D/S283D had significantly greater ion conductance for Na+ and K+ , whereas the S280A single phosphonull mutant had greater water permeability. We observed a phosphorylation-dependent inverse relationship between AtPIP2;1 water and ion transport with a 10-fold change in both. The results revealed that phosphorylation of S280 and S283 influences the preferential facilitation of ion or water transport by AtPIP2;1. The results also hint that other regulatory sites play roles that are yet to be elucidated. Expression of the AtPIP2;1 phosphorylation mutants in Saccharomyces cerevisiae confirmed that phosphorylation influences plasma membrane localization, and revealed higher Na+ accumulation for S280A and S283D mutants. Collectively, the results show that phosphorylation in the C-terminal domain of AtPIP2;1 influences its subcellular localization and cation transport capacity.
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Affiliation(s)
- Jiaen Qiu
- ARC Centre of Excellence in Plant Energy Biology, School of Agriculture, Food and Wine, The University of Adelaide, Adelaide, Australia
| | - Samantha A McGaughey
- ARC Centre of Excellence in Plant Energy Biology, School of Agriculture, Food and Wine, The University of Adelaide, Adelaide, Australia
- ARC Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology, Australian National University, Acton, Australia
| | - Michael Groszmann
- ARC Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology, Australian National University, Acton, Australia
| | - Stephen D Tyerman
- ARC Centre of Excellence in Plant Energy Biology, School of Agriculture, Food and Wine, The University of Adelaide, Adelaide, Australia
| | - Caitlin S Byrt
- ARC Centre of Excellence in Plant Energy Biology, School of Agriculture, Food and Wine, The University of Adelaide, Adelaide, Australia
- ARC Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology, Australian National University, Acton, Australia
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28
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Heyman SN, Bursztyn M, Abassi Z. Low-salt diet and renal safety: taken with a pinch of salt. J Physiol 2020; 598:5299-5300. [PMID: 32965747 DOI: 10.1113/jp280716] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2020] [Accepted: 09/22/2020] [Indexed: 11/08/2022] Open
Affiliation(s)
- Samuel N Heyman
- Department of Medicine, Hadassah Hebrew University Hospital, Mt Scopus, Jerusalem, Israel
| | - Michael Bursztyn
- Department of Medicine, Hadassah Hebrew University Hospital, Mt Scopus, Jerusalem, Israel
| | - Zaid Abassi
- Department of Physiology and Biophysics, Ruth and Bruce Rappaport Faculty of Medicine, Technion-IIT, Haifa, Israel.,Department of Laboratory Medicine, Rambam Health Care Campus, Haifa, Israel
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29
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Boyd-Shiwarski CR, Weaver CJ, Beacham RT, Shiwarski DJ, Connolly KA, Nkashama LJ, Mutchler SM, Griffiths SE, Knoell SA, Sebastiani RS, Ray EC, Marciszyn AL, Subramanya AR. Effects of extreme potassium stress on blood pressure and renal tubular sodium transport. Am J Physiol Renal Physiol 2020; 318:F1341-F1356. [PMID: 32281415 PMCID: PMC7311711 DOI: 10.1152/ajprenal.00527.2019] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
We characterized mouse blood pressure and ion transport in the setting of commonly used rodent diets that drive K+ intake to the extremes of deficiency and excess. Male 129S2/Sv mice were fed either K+-deficient, control, high-K+ basic, or high-KCl diets for 10 days. Mice maintained on a K+-deficient diet exhibited no change in blood pressure, whereas K+-loaded mice developed an ~10-mmHg blood pressure increase. Following challenge with NaCl, K+-deficient mice developed a salt-sensitive 8 mmHg increase in blood pressure, whereas blood pressure was unchanged in mice fed high-K+ diets. Notably, 10 days of K+ depletion induced diabetes insipidus and upregulation of phosphorylated NaCl cotransporter, proximal Na+ transporters, and pendrin, likely contributing to the K+-deficient NaCl sensitivity. While the anionic content with high-K+ diets had distinct effects on transporter expression along the nephron, both K+ basic and KCl diets had a similar increase in blood pressure. The blood pressure elevation on high-K+ diets correlated with increased Na+-K+-2Cl- cotransporter and γ-epithelial Na+ channel expression and increased urinary response to furosemide and amiloride. We conclude that the dietary K+ maneuvers used here did not recapitulate the inverse effects of K+ on blood pressure observed in human epidemiological studies. This may be due to the extreme degree of K+ stress, the low-Na+-to-K+ ratio, the duration of treatment, and the development of other coinciding events, such as diabetes insipidus. These factors must be taken into consideration when studying the physiological effects of dietary K+ loading and depletion.
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Affiliation(s)
- Cary R. Boyd-Shiwarski
- 1Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Claire J. Weaver
- 1Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Rebecca T. Beacham
- 1Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Daniel J. Shiwarski
- 2Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania
| | - Kelly A. Connolly
- 1Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Lubika J. Nkashama
- 1Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Stephanie M. Mutchler
- 1Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Shawn E. Griffiths
- 1Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Sophia A. Knoell
- 1Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Romano S. Sebastiani
- 1Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Evan C. Ray
- 1Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Allison L. Marciszyn
- 1Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Arohan R. Subramanya
- 1Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania,3Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania,4Veterans Administration, Pittsburgh Healthcare System, Pittsburgh Pennsylvania
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30
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Yang N, Hong NJ, Garvin JL. Dietary fructose enhances angiotensin II-stimulated Na + transport via activation of PKC-α in renal proximal tubules. Am J Physiol Renal Physiol 2020; 318:F1513-F1519. [PMID: 32390510 DOI: 10.1152/ajprenal.00543.2019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Angiotensin II (ANG II) stimulates proximal nephron transport via activation of classical protein kinase C (PKC) isoforms. Acute fructose treatment stimulates PKC and dietary fructose enhances ANG II's ability to stimulate Na+ transport, but the mechanisms are unclear. We hypothesized that dietary fructose enhances ANG II's ability to stimulate renal proximal tubule Na+ reabsorption by augmenting PKC-α activation and increases in intracellular Ca2+. We measured total and isoform-specific PKC activity, basal and ANG II-stimulated oxygen consumption, a surrogate of Na+ reabsorption, and intracellular Ca2+ in proximal tubules from rats given either 20% fructose in their drinking water (fructose group) or tap water (control group). Total PKC activity was measured by ELISA. PKC-α, PKC-β, and PKC-γ activities were assessed by measuring particulate-to-soluble ratios. Intracelluar Ca2+ was measured using fura 2. ANG II stimulated total PKC activity by 53 ± 15% in the fructose group but not in the control group (-15 ± 11%, P < 0.002). ANG II stimulated PKC-α by 0.134 ± 0.026 but not in the control group (-0.002 ± 0.020, P < 0.002). ANG II increased PKC-γ activity by 0.008 ± 0.003 in the fructose group but not in the control group (P < 0.046). ANG II did not stimulate PKC-β in either group. ANG II increased Na+ transport by 454 ± 87 nmol·min-1·mg protein-1 in fructose group, and the PKC-α/β inhibitor Gö6976 blocked this increase (-96 ± 205 nmol·min-1·mg protein-1, P < 0.045). ANG II increased intracellular Ca2+ by 148 ± 53 nM in the fructose group but only by 43 ± 10 nM in the control group (P < 0.035). The intracellular Ca2+ chelator BAPTA blocked the ANG II-induced increase in Na+ transport in the fructose group. We concluded that dietary fructose enhances ANG II's ability to stimulate renal proximal tubule Na+ reabsorption by augmenting PKC-α activation via elevated increases in intacellular Ca2+.
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Affiliation(s)
- Nianxin Yang
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, Ohio.,Biochemistry, Molecular, Cellular and Developmental Biology, University of California, Davis, California
| | - Nancy J Hong
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, Ohio
| | - Jeffrey L Garvin
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, Ohio
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31
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Abstract
Na+ K+ ATPase (NKA) is crucial to branchial ion transport as it uses the energy from ATP to move Na+ against its electrochemical gradient. When fish encounter extremely dilute environments the energy available from ATP hydrolysis may not be sufficient to overcome thermodynamic constraints on ion transport. Yet many fish species-including zebrafish-are capable of surviving in dilute environments. Despite much study, the physiological mechanisms by which this occurs remain poorly understood. Here, we demonstrate that zebrafish acclimated to less than 10 µM Na+ water exhibit upregulation of a specific NKA α subunit ( zatp1a1a.5) that, unlike most NKA heterotrimers, would result in transfer of only a single Na+ and K+ per ATP hydrolysis reaction. Thermodynamic models demonstrate that this change is sufficient to reduce the activation energy of NKA, allowing it to overcome the adverse electrochemical gradient imposed by dilute freshwater. Importantly, upregulation of zatp1a1a.5 also coincides with the recovery of whole body Na+ post-transfer, which occurs within 24 h. While these structural modifications are crucial for allowing zebrafish to survive in ion-poor environments, phylogenetic and structural analysis of available α subunits from a range of teleosts suggests this adaptation is not widely distributed.
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Affiliation(s)
- Andrew J Esbaugh
- 1 Department of Marine Science, University of Texas Marine Science Institute, University of Texas at Austin , Austin, TX , USA
| | - Kevin V Brix
- 2 Marine Biology and Ecology, Rosenstiel School of Marine and Atmospheric Science, University of Miami , Coral Gables, FL , USA
| | - Martin Grosell
- 2 Marine Biology and Ecology, Rosenstiel School of Marine and Atmospheric Science, University of Miami , Coral Gables, FL , USA
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32
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Veiras LC, McFarlin BE, Ralph DL, Buncha V, Prescott J, Shirvani BS, McDonough JC, Ha D, Giani J, Gurley SB, Mamenko M, McDonough AA. Electrolyte and transporter responses to angiotensin II induced hypertension in female and male rats and mice. Acta Physiol (Oxf) 2020; 229:e13448. [PMID: 31994810 DOI: 10.1111/apha.13448] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Revised: 01/21/2020] [Accepted: 01/23/2020] [Indexed: 12/15/2022]
Abstract
AIM Sexual dimorphisms are evident along the nephron: Females (F) exhibit higher ratios of renal distal to proximal Na+ transporters' abundance, greater lithium clearance (CLi ) more rapid natriuresis in response to saline infusion and lower plasma [K+ ] vs. males (M). During angiotensin II infusion hypertension (AngII-HTN) M exhibit distal Na+ transporter activation, lower proximal and medullary loop transporters, blunted natriuresis in response to saline load, and reduced plasma [K+ ]. This study aimed to determine whether responses of F to AngII-HTN mimicked those in M or were impacted by sexual dimorphisms evident at baseline. METHODS Sprague Dawley rats and C57BL/6 mice were AngII infused via osmotic minipumps 2 and 3 weeks, respectively, and assessed by metabolic cage collections, tail-cuff sphygmomanometer, semi-quantitative immunoblotting of kidney and patch-clamp electrophysiology. RESULTS In F rats, AngII-infusion increased BP to 190 mm Hg, increased phosphorylation of cortical NKCC2, NCC and cleavage of ENaC two to threefold, increased ENaC channel activity threefold and aldosterone 10-fold. K+ excretion increased and plasma [K+ ] decreased. Evidence of natriuresis in F included increased urine Na+ excretion and CLi , and decreased medullary NHE3, NKCC2 and Na,K-ATPase abundance. In C57BL/6 mice, AngII-HTN increased abundance of distal Na+ transporters, suppressed proximal-medullary transporters and reduced plasma [K+ ] in both F and M. CONCLUSION Despite baseline sexual dimorphisms, AngII-HTN provokes similar increases in BP, aldosterone, distal transporters, ENaC channel activation and K+ loss accompanied by similar suppression of proximal and loop Na+ transporters, natriuresis and diuresis in females and males.
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Affiliation(s)
- Luciana C. Veiras
- Department of Physiology and Neuroscience Keck School of Medicine of USC Los Angeles CA USA
- Department of Biomedical Sciences Cedars‐Sinai Medical Center Los Angeles CA USA
| | - Brandon E. McFarlin
- Department of Physiology and Neuroscience Keck School of Medicine of USC Los Angeles CA USA
| | - Donna L. Ralph
- Department of Physiology and Neuroscience Keck School of Medicine of USC Los Angeles CA USA
| | - Vadym Buncha
- Department of Physiology Medical College of Georgia at Augusta University Augusta GA USA
| | - Jessica Prescott
- Department of Physiology and Neuroscience Keck School of Medicine of USC Los Angeles CA USA
| | - Borna S. Shirvani
- Department of Physiology and Neuroscience Keck School of Medicine of USC Los Angeles CA USA
| | - Jillian C. McDonough
- Department of Physiology and Neuroscience Keck School of Medicine of USC Los Angeles CA USA
| | - Darren Ha
- Department of Physiology and Neuroscience Keck School of Medicine of USC Los Angeles CA USA
| | - Jorge Giani
- Department of Biomedical Sciences Cedars‐Sinai Medical Center Los Angeles CA USA
| | - Susan B. Gurley
- Division of Nephrology and Hypertension Oregon Health and Science University Portland OR USA
| | - Mykola Mamenko
- Department of Physiology Medical College of Georgia at Augusta University Augusta GA USA
| | - Alicia A. McDonough
- Department of Physiology and Neuroscience Keck School of Medicine of USC Los Angeles CA USA
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33
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Abstract
Kidney water conservation requires a hypertonic medullary interstitium, NaCl in the outer medulla and NaCl and urea in the inner medulla, plus a vascular configuration that protects against washout. In this work, a multisolute model of the rat kidney is revisited to examine its capacity to simulate antidiuresis. The first step was to streamline model computation by parallelizing its Jacobian calculation, thus allowing finer medullary spatial resolution and more extensive examination of model parameters. It is found that outer medullary NaCl is modestly increased when transporter density in ascending Henle limbs from juxtamedullary nephrons is scaled to match the greater juxtamedullary solute flow. However, higher NaCl transport produces greater CO2 generation and, by virtue of countercurrent vascular flows, establishment of high medullary Pco2. This CO2 gradient can be mitigated by assuming that a fraction of medullary transport is powered anaerobically. Reducing vascular flows or increasing vessel permeabilities does little to further increase outer medullary solute gradients. In contrast to medullary models of others, vessels in this model have solute reflection coefficients close to zero; increasing these coefficients provides little enhancement of solute profiles but does generate high interstitial pressures, which distort tubule architecture. Increasing medullary urea delivery via entering vasa recta increases inner medullary urea, although not nearly to levels found in rats. In summary, 1) medullary Na+ and urea gradients are not captured by the model and 2) the countercurrent architecture that provides antidiuresis also produces exaggerated Pco2 profiles and is an unappreciated constraint on models of medullary function.
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Affiliation(s)
- Alan M Weinstein
- Department of Physiology and Biophysics and Department of Medicine, Weill Medical College of Cornell University, New York, New York
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Kryvenko V, Wessendorf M, Morty RE, Herold S, Seeger W, Vagin O, Dada LA, Sznajder JI, Vadász I. Hypercapnia Impairs Na,K-ATPase Function by Inducing Endoplasmic Reticulum Retention of the β-Subunit of the Enzyme in Alveolar Epithelial Cells. Int J Mol Sci 2020; 21:ijms21041467. [PMID: 32098115 PMCID: PMC7073107 DOI: 10.3390/ijms21041467] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 02/16/2020] [Accepted: 02/17/2020] [Indexed: 01/02/2023] Open
Abstract
Alveolar edema, impaired alveolar fluid clearance, and elevated CO2 levels (hypercapnia) are hallmarks of the acute respiratory distress syndrome (ARDS). This study investigated how hypercapnia affects maturation of the Na,K-ATPase (NKA), a key membrane transporter, and a cell adhesion molecule involved in the resolution of alveolar edema in the endoplasmic reticulum (ER). Exposure of human alveolar epithelial cells to elevated CO2 concentrations caused a significant retention of NKA-β in the ER and, thus, decreased levels of the transporter in the Golgi apparatus. These effects were associated with a marked reduction of the plasma membrane (PM) abundance of the NKA-α/β complex as well as a decreased total and ouabain-sensitive ATPase activity. Furthermore, our study revealed that the ER-retained NKA-β subunits were only partially assembled with NKA α-subunits, which suggests that hypercapnia modifies the ER folding environment. Moreover, we observed that elevated CO2 levels decreased intracellular ATP production and increased ER protein and, particularly, NKA-β oxidation. Treatment with α-ketoglutaric acid (α-KG), which is a metabolite that has been shown to increase ATP levels and rescue mitochondrial function in hypercapnia-exposed cells, attenuated the deleterious effects of elevated CO2 concentrations and restored NKA PM abundance and function. Taken together, our findings provide new insights into the regulation of NKA in alveolar epithelial cells by elevated CO2 levels, which may lead to the development of new therapeutic approaches for patients with ARDS and hypercapnia.
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Affiliation(s)
- Vitalii Kryvenko
- Department of Internal Medicine, Justus Liebig University, Universities of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), 35392 Giessen, Germany; (V.K.); (M.W.); (R.E.M.); (S.H.); (W.S.)
- The Cardio-Pulmonary Institute (CPI), 35392 Giessen, Germany
| | - Miriam Wessendorf
- Department of Internal Medicine, Justus Liebig University, Universities of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), 35392 Giessen, Germany; (V.K.); (M.W.); (R.E.M.); (S.H.); (W.S.)
| | - Rory E. Morty
- Department of Internal Medicine, Justus Liebig University, Universities of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), 35392 Giessen, Germany; (V.K.); (M.W.); (R.E.M.); (S.H.); (W.S.)
- The Cardio-Pulmonary Institute (CPI), 35392 Giessen, Germany
- Department of Lung Development and Remodeling, Max Planck Institute for Heart and Lung Research, 61231 Bad Nauheim, Germany
| | - Susanne Herold
- Department of Internal Medicine, Justus Liebig University, Universities of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), 35392 Giessen, Germany; (V.K.); (M.W.); (R.E.M.); (S.H.); (W.S.)
- The Cardio-Pulmonary Institute (CPI), 35392 Giessen, Germany
| | - Werner Seeger
- Department of Internal Medicine, Justus Liebig University, Universities of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), 35392 Giessen, Germany; (V.K.); (M.W.); (R.E.M.); (S.H.); (W.S.)
- The Cardio-Pulmonary Institute (CPI), 35392 Giessen, Germany
- Department of Lung Development and Remodeling, Max Planck Institute for Heart and Lung Research, 61231 Bad Nauheim, Germany
| | - Olga Vagin
- Department of Physiology, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA 90095, USA;
- Veterans Administration Greater Los Angeles Healthcare System, Los Angeles, CA 90073, USA
| | - Laura A. Dada
- Division of Pulmonary and Critical Care Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA; (L.A.D.); (J.I.S.)
| | - Jacob I. Sznajder
- Division of Pulmonary and Critical Care Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA; (L.A.D.); (J.I.S.)
| | - István Vadász
- Department of Internal Medicine, Justus Liebig University, Universities of Giessen and Marburg Lung Center (UGMLC), Member of the German Center for Lung Research (DZL), 35392 Giessen, Germany; (V.K.); (M.W.); (R.E.M.); (S.H.); (W.S.)
- The Cardio-Pulmonary Institute (CPI), 35392 Giessen, Germany
- Correspondence: ; Tel.: +49-641-985-42354; Fax: +49-641-985-42359
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Nattramilarasu PK, Bücker R, Lobo de Sá FD, Fromm A, Nagel O, Lee IFM, Butkevych E, Mousavi S, Genger C, Kløve S, Heimesaat MM, Bereswill S, Schweiger MR, Nielsen HL, Troeger H, Schulzke JD. Campylobacter concisus Impairs Sodium Absorption in Colonic Epithelium via ENaC Dysfunction and Claudin-8 Disruption. Int J Mol Sci 2020; 21:ijms21020373. [PMID: 31936044 PMCID: PMC7013563 DOI: 10.3390/ijms21020373] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Revised: 12/31/2019] [Accepted: 12/31/2019] [Indexed: 12/12/2022] Open
Abstract
The epithelial sodium channel (ENaC) can increase the colonic absorptive capacity for salt and water. Campylobacter concisus is a common pathogenic epsilonproteobacterium, causing enteritis and diarrhea. It can induce barrier dysfunction in the intestine, but its influence on intestinal transport function is still unknown. Therefore, our study aimed to characterize C. concisus effects on ENaC using the HT-29/B6-GR/MR (epithelial cell line HT-29/B6 transfected with glucocorticoid and mineralocorticoid receptors) cell model and mouse colon. In Ussing chambers, C. concisus infection inhibited ENaC-dependent Na+ transport as indicated by a reduction in amiloride-sensitive short circuit current (−55%, n = 15, p < 0.001). This occurred via down-regulation of β- and γ-ENaC mRNA expression and ENaC ubiquitination due to extracellular signal-regulated kinase (ERK)1/2 activation, predicted by Ingenuity Pathway Analysis (IPA). In parallel, C. concisus reduced the expression of the sealing tight junction (TJ) protein claudin-8 and induced claudin-8 redistribution off the TJ domain of the enterocytes, which facilitates the back leakage of Na+ ions into the intestinal lumen. In conclusion, C. concisus caused ENaC dysfunction via interleukin-32-regulated ERK1/2, as well as claudin-8-dependent barrier dysfunction—both of which contribute to Na+ malabsorption and diarrhea.
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Affiliation(s)
- Praveen Kumar Nattramilarasu
- Institute of Clinical Physiology/Nutritional Medicine, Medical Department, Division of Gastroenterology, Infectiology and Rheumatology, Charité—Universitätsmedizin Berlin, 12203 Berlin, Germany
| | - Roland Bücker
- Institute of Clinical Physiology/Nutritional Medicine, Medical Department, Division of Gastroenterology, Infectiology and Rheumatology, Charité—Universitätsmedizin Berlin, 12203 Berlin, Germany
| | - Fábia Daniela Lobo de Sá
- Institute of Clinical Physiology/Nutritional Medicine, Medical Department, Division of Gastroenterology, Infectiology and Rheumatology, Charité—Universitätsmedizin Berlin, 12203 Berlin, Germany
| | - Anja Fromm
- Institute of Clinical Physiology/Nutritional Medicine, Medical Department, Division of Gastroenterology, Infectiology and Rheumatology, Charité—Universitätsmedizin Berlin, 12203 Berlin, Germany
| | - Oliver Nagel
- Institute of Clinical Physiology/Nutritional Medicine, Medical Department, Division of Gastroenterology, Infectiology and Rheumatology, Charité—Universitätsmedizin Berlin, 12203 Berlin, Germany
| | - In-Fah Maria Lee
- Institute of Clinical Physiology/Nutritional Medicine, Medical Department, Division of Gastroenterology, Infectiology and Rheumatology, Charité—Universitätsmedizin Berlin, 12203 Berlin, Germany
| | - Eduard Butkevych
- Institute of Clinical Physiology/Nutritional Medicine, Medical Department, Division of Gastroenterology, Infectiology and Rheumatology, Charité—Universitätsmedizin Berlin, 12203 Berlin, Germany
| | - Soraya Mousavi
- Institute of Microbiology, Infectious Diseases and Immunology, Charité—Universitätsmedizin Berlin, Campus Benjamin Franklin, 14195 Berlin, Germany
| | - Claudia Genger
- Institute of Microbiology, Infectious Diseases and Immunology, Charité—Universitätsmedizin Berlin, Campus Benjamin Franklin, 14195 Berlin, Germany
| | - Sigri Kløve
- Institute of Microbiology, Infectious Diseases and Immunology, Charité—Universitätsmedizin Berlin, Campus Benjamin Franklin, 14195 Berlin, Germany
| | - Markus M. Heimesaat
- Institute of Microbiology, Infectious Diseases and Immunology, Charité—Universitätsmedizin Berlin, Campus Benjamin Franklin, 14195 Berlin, Germany
| | - Stefan Bereswill
- Institute of Microbiology, Infectious Diseases and Immunology, Charité—Universitätsmedizin Berlin, Campus Benjamin Franklin, 14195 Berlin, Germany
| | - Michal R. Schweiger
- Laboratory for Epigenetics and Tumour genetics, University Hospital Cologne and Centre for Molecular Medicine Cologne, 50931 Cologne, Germany
| | - Hans Linde Nielsen
- Department of Clinical Microbiology, Aalborg University Hospital, 9000 Aalborg, Denmark
- Department of Clinical Medicine, Aalborg University, 9000 Aalborg, Denmark
| | - Hanno Troeger
- Medical Department, Division of Gastroenterology, Infectiology and Rheumatology, Charité—Universitätsmedizin Berlin, 12203 Berlin, Germany
| | - Jörg-Dieter Schulzke
- Institute of Clinical Physiology/Nutritional Medicine, Medical Department, Division of Gastroenterology, Infectiology and Rheumatology, Charité—Universitätsmedizin Berlin, 12203 Berlin, Germany
- Correspondence:
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36
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Scambler T, Jarosz-Griffiths HH, Lara-Reyna S, Pathak S, Wong C, Holbrook J, Martinon F, Savic S, Peckham D, McDermott MF. ENaC-mediated sodium influx exacerbates NLRP3-dependent inflammation in cystic fibrosis. eLife 2019; 8:49248. [PMID: 31532390 PMCID: PMC6764826 DOI: 10.7554/elife.49248] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Accepted: 09/17/2019] [Indexed: 12/13/2022] Open
Abstract
Cystic Fibrosis (CF) is a monogenic disease caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, resulting in defective CFTR-mediated chloride and bicarbonate transport, with dysregulation of epithelial sodium channels (ENaC). These changes alter fluid and electrolyte homeostasis and result in an exaggerated proinflammatory response driven, in part, by infection. We tested the hypothesis that NLRP3 inflammasome activation and ENaC upregulation drives exaggerated innate-immune responses in this multisystem disease. We identify an enhanced proinflammatory signature, as evidenced by increased levels of IL-18, IL-1β, caspase-1 activity and ASC-speck release in monocytes, epithelia and serum with CF-associated mutations; these differences were reversed by pretreatment with NLRP3 inflammasome inhibitors and notably, inhibition of amiloride-sensitive sodium (Na+) channels. Overexpression of β-ENaC, in the absence of CFTR dysfunction, increased NLRP3-mediated inflammation, indicating that dysregulated, ENaC-dependent signalling may drive exaggerated inflammatory responses in CF. These data support a role for sodium in modulating NLRP3 inflammasome activation.
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Affiliation(s)
- Thomas Scambler
- Leeds Institute of Rheumatic and Musculoskeletal Medicine, University of Leeds, Leeds, United Kingdom
| | - Heledd H Jarosz-Griffiths
- Leeds Institute of Rheumatic and Musculoskeletal Medicine, University of Leeds, Leeds, United Kingdom.,Leeds Institute of Medical Research, University of Leeds, Leeds, United Kingdom.,Leeds Cystic Fibrosis Trust Strategic Research Centre, University of Leeds, Leeds, United Kingdom
| | - Samuel Lara-Reyna
- Leeds Institute of Rheumatic and Musculoskeletal Medicine, University of Leeds, Leeds, United Kingdom.,Leeds Institute of Medical Research, University of Leeds, Leeds, United Kingdom
| | - Shelly Pathak
- Leeds Institute of Rheumatic and Musculoskeletal Medicine, University of Leeds, Leeds, United Kingdom
| | - Chi Wong
- Leeds Institute of Rheumatic and Musculoskeletal Medicine, University of Leeds, Leeds, United Kingdom.,Leeds Institute of Medical Research, University of Leeds, Leeds, United Kingdom.,Leeds Cystic Fibrosis Trust Strategic Research Centre, University of Leeds, Leeds, United Kingdom
| | - Jonathan Holbrook
- Leeds Institute of Rheumatic and Musculoskeletal Medicine, University of Leeds, Leeds, United Kingdom.,Leeds Institute of Medical Research, University of Leeds, Leeds, United Kingdom.,Leeds Cystic Fibrosis Trust Strategic Research Centre, University of Leeds, Leeds, United Kingdom
| | - Fabio Martinon
- Leeds Cystic Fibrosis Trust Strategic Research Centre, University of Leeds, Leeds, United Kingdom.,Department of Biochemistry, University of Lausanne, Lausanne, Switzerland
| | - Sinisa Savic
- Leeds Institute of Rheumatic and Musculoskeletal Medicine, University of Leeds, Leeds, United Kingdom.,Leeds Cystic Fibrosis Trust Strategic Research Centre, University of Leeds, Leeds, United Kingdom.,Department of Clinical Immunology and Allergy, St James's University Hospital, Leeds, United Kingdom
| | - Daniel Peckham
- Leeds Institute of Medical Research, University of Leeds, Leeds, United Kingdom.,Leeds Cystic Fibrosis Trust Strategic Research Centre, University of Leeds, Leeds, United Kingdom.,Adult Cystic Fibrosis Unit, St James' University Hospital, Leeds, United Kingdom
| | - Michael F McDermott
- Leeds Institute of Rheumatic and Musculoskeletal Medicine, University of Leeds, Leeds, United Kingdom.,Leeds Cystic Fibrosis Trust Strategic Research Centre, University of Leeds, Leeds, United Kingdom
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Nakamura M, Tsukada H, Seki G, Satoh N, Mizuno T, Fujii W, Horita S, Moriya K, Sato Y, Kume H, Nangaku M, Suzuki M. Insulin promotes sodium transport but suppresses gluconeogenesis via distinct cellular pathways in human and rat renal proximal tubules. Kidney Int 2019; 97:316-326. [PMID: 31735358 DOI: 10.1016/j.kint.2019.08.021] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2018] [Revised: 08/02/2019] [Accepted: 08/08/2019] [Indexed: 01/11/2023]
Abstract
Insulin is known to promote sodium transport and regulate gluconeogenesis in renal proximal tubules. Although protein kinase B (also known as Akt) and mammalian target of rapamycin complexes (mTORC) have been established as key regulators in the insulin signaling pathway, their roles in proximal tubules are poorly understood. To help define this, we examined the components of insulin signaling in sodium transport and gluconeogenesis in isolated human and rat proximal tubules, and also investigated the role of insulin in sodium handling and mTORC1 in insulin signaling in vivo. In isolated human and rat proximal tubules, Akt and mTORC1/2 inhibition suppressed insulin-stimulated sodium-bicarbonate co-transporter 1 (NBCe1) activity, whereas mTORC1 inhibition had no effect. Akt2 and mTORC2 gene silencing largely inhibited insulin-stimulated NBCe1 activity, whereas silencing of Akt1 and mTORC1 had no effect. Furthermore, insulin decreased sodium excretion, and this effect depended on phosphoinositide 3 kinase in vivo. Moreover, insulin reduced glucose production in rat proximal tubules and the expression of gluconeogenic genes in human and rat proximal tubules. Akt and mTORC1 inhibition largely abolished the observed insulin-mediated inhibitory effects. Gene silencing of insulin receptor substrate 1 (IRS1), Akt2, mTORC1, and mTORC2 also abolished insulin-mediated inhibition of gluconeogenesis. Additionally, in vivo, mTORC1 inhibition abolished insulin-mediated inhibitory effects in rat proximal tubules, although not in liver. These results indicate that insulin-stimulated proximal tubule sodium transport is mediated via the Akt2/mTORC2 pathway, whereas insulin-suppressed proximal tubule gluconeogenesis is mediated via the IRS1/Akt2/mTORC1/2 pathway. Thus, distinct pathways may play important roles in hypertension and hyperglycemia in metabolic syndrome and diabetes.
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Affiliation(s)
- Motonobu Nakamura
- Division of Nephrology and Endocrinology, The University of Tokyo, Tokyo, Japan
| | - Hiroyuki Tsukada
- Division of Nephrology and Endocrinology, The University of Tokyo, Tokyo, Japan
| | - George Seki
- Department of Nephrology, Yaizu City Hospital, Shizuoka, Japan
| | - Nobuhiko Satoh
- Division of Nephrology and Endocrinology, The University of Tokyo, Tokyo, Japan; Department of Infection Control and Prevention, The University of Tokyo, Tokyo, Japan
| | - Tomohito Mizuno
- Division of Nephrology and Endocrinology, The University of Tokyo, Tokyo, Japan
| | - Wataru Fujii
- Division of Nephrology and Endocrinology, The University of Tokyo, Tokyo, Japan
| | - Shoko Horita
- Division of Nephrology and Endocrinology, The University of Tokyo, Tokyo, Japan
| | - Kyoji Moriya
- Department of Infection Control and Prevention, The University of Tokyo, Tokyo, Japan
| | - Yusuke Sato
- Department of Urology, The University of Tokyo, Tokyo, Japan
| | - Haruki Kume
- Department of Urology, The University of Tokyo, Tokyo, Japan
| | - Masaomi Nangaku
- Division of Nephrology and Endocrinology, The University of Tokyo, Tokyo, Japan
| | - Masashi Suzuki
- Health Service Center, Tokyo Gakugei University, Tokyo, Japan.
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38
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Canonica J, Frateschi S, Boscardin E, Ebering A, Sergi C, Jäger Y, Peyrollaz T, Mérillat AM, Maillard M, Klusonova P, Odermatt A, Koesters R, Debonneville A, Staub O, Verouti SN, Hummler E. Lack of Renal Tubular Glucocorticoid Receptor Decreases the Thiazide-Sensitive Na +/Cl - Cotransporter NCC and Transiently Affects Sodium Handling. Front Physiol 2019; 10:989. [PMID: 31474871 PMCID: PMC6702950 DOI: 10.3389/fphys.2019.00989] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Accepted: 07/18/2019] [Indexed: 12/14/2022] Open
Abstract
Chronic glucocorticoid infusion impairs NCC activity and induces a non-dipping profile in mice, suggesting that glucocorticoids are essential for daily blood pressure variations. In this paper, we studied mice lacking the renal tubular glucocorticoid receptor (GR) in adulthood (GR knockouts, Nr3c1Pax8/LC1). Upon standard salt diet, Nr3c1Pax8/LC1 mice grow normally, but show reduced NCC activity despite normal plasma aldosterone levels. Following diet switch to low sodium, Nr3c1Pax8/LC1 mice exhibit a transient but significant reduction in the activity of NCC and expression of NHE3 and NKCC2 accompanied by significant increased Spak activity. This is followed by transiently increased urinary sodium excretion and higher plasma aldosterone concentrations. Plasma corticosterone levels and 11βHSD2 mRNA expression and activity in the whole kidney remain unchanged. High salt diet does not affect whole body Na+ and/or K+ balance and NCC activity is not reduced, but leads to a significant increase in diastolic blood pressure dipping in Nr3c1Pax8/LC1 mice. When high sodium treatment is followed by 48 h of darkness, NCC abundance is reduced in knockout mice although activity is not different. Our data show that upon Na+ restriction renal tubular GR-deficiency transiently affects Na+ handling and transport pathways. Overall, upon standard, low Na+ and high Na+ diet exposure Na+ and K+ balance is maintained as evidenced by normal plasma and urinary Na+ and K+ and aldosterone concentrations.
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Affiliation(s)
- Jérémie Canonica
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland.,National Centre of Competence in Research "Kidney.CH", Lausanne, Switzerland
| | - Simona Frateschi
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland.,National Centre of Competence in Research "Kidney.CH", Lausanne, Switzerland
| | - Emilie Boscardin
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland.,National Centre of Competence in Research "Kidney.CH", Lausanne, Switzerland
| | - Anna Ebering
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland
| | - Chloé Sergi
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland
| | - Yannick Jäger
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland
| | - Thibaud Peyrollaz
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland
| | - Anne-Marie Mérillat
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland
| | - Marc Maillard
- Department of Nephrology Service, University Hospital of Lausanne (CHUV), Lausanne, Switzerland
| | - Petra Klusonova
- Department of Pharmaceutical Sciences, University of Basel, Basel, Switzerland
| | - Alex Odermatt
- National Centre of Competence in Research "Kidney.CH", Lausanne, Switzerland.,Department of Pharmaceutical Sciences, University of Basel, Basel, Switzerland
| | - Robert Koesters
- Hôpital Tenon, Université Pierre et Marie Curie, Paris, France
| | - Anne Debonneville
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland
| | - Olivier Staub
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland.,National Centre of Competence in Research "Kidney.CH", Lausanne, Switzerland
| | - Sophia N Verouti
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland
| | - Edith Hummler
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland.,National Centre of Competence in Research "Kidney.CH", Lausanne, Switzerland
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Locascio A, Andrés-Colás N, Mulet JM, Yenush L. Saccharomyces cerevisiae as a Tool to Investigate Plant Potassium and Sodium Transporters. Int J Mol Sci 2019; 20:E2133. [PMID: 31052176 PMCID: PMC6539216 DOI: 10.3390/ijms20092133] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 04/26/2019] [Accepted: 04/29/2019] [Indexed: 12/20/2022] Open
Abstract
Sodium and potassium are two alkali cations abundant in the biosphere. Potassium is essential for plants and its concentration must be maintained at approximately 150 mM in the plant cell cytoplasm including under circumstances where its concentration is much lower in soil. On the other hand, sodium must be extruded from the plant or accumulated either in the vacuole or in specific plant structures. Maintaining a high intracellular K+/Na+ ratio under adverse environmental conditions or in the presence of salt is essential to maintain cellular homeostasis and to avoid toxicity. The baker's yeast, Saccharomyces cerevisiae, has been used to identify and characterize participants in potassium and sodium homeostasis in plants for many years. Its utility resides in the fact that the electric gradient across the membrane and the vacuoles is similar to plants. Most plant proteins can be expressed in yeast and are functional in this unicellular model system, which allows for productive structure-function studies for ion transporting proteins. Moreover, yeast can also be used as a high-throughput platform for the identification of genes that confer stress tolerance and for the study of protein-protein interactions. In this review, we summarize advances regarding potassium and sodium transport that have been discovered using the yeast model system, the state-of-the-art of the available techniques and the future directions and opportunities in this field.
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Affiliation(s)
- Antonella Locascio
- Instituto de Biología Molecular y Celular de Plantas, Universitat Politècnica de València-Consejo Superior de Investigaciones Científicas, 46022 Valencia, Spain.
| | - Nuria Andrés-Colás
- Instituto de Biología Molecular y Celular de Plantas, Universitat Politècnica de València-Consejo Superior de Investigaciones Científicas, 46022 Valencia, Spain.
| | - José Miguel Mulet
- Instituto de Biología Molecular y Celular de Plantas, Universitat Politècnica de València-Consejo Superior de Investigaciones Científicas, 46022 Valencia, Spain.
| | - Lynne Yenush
- Instituto de Biología Molecular y Celular de Plantas, Universitat Politècnica de València-Consejo Superior de Investigaciones Científicas, 46022 Valencia, Spain.
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Chung S, Kim S, Son M, Kim M, Koh ES, Shin SJ, Ko SH, Kim HS. Empagliflozin Contributes to Polyuria via Regulation of Sodium Transporters and Water Channels in Diabetic Rat Kidneys. Front Physiol 2019; 10:271. [PMID: 30941057 PMCID: PMC6433843 DOI: 10.3389/fphys.2019.00271] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Accepted: 02/28/2019] [Indexed: 12/12/2022] Open
Abstract
Besides lowering glucose, empagliflozin, a selective sodium-glucose cotransporter-2 (SGLT2) inhibitor, have been known to provide cardiovascular and renal protection due to effects on diuresis and natriuresis. However, the natriuretic effect of SGLT2 inhibitors has been reported to be transient, and long-term data related to diuretic change are sparse. This study was performed to assess the renal effects of a 12-week treatment with empagliflozin (3 mg/kg) in diabetic OLETF rats by comparing it with other antihyperglycemic agents including lixisenatide (10 μg/kg), a glucagon-like peptide receptor-1 agonist, and voglibose (0.6 mg/kg), an α-glucosidase inhibitor. At 12 weeks of treatment, empagliflozin-treated diabetic rats produced still high urine volume and glycosuria, and showed significantly higher electrolyte-free water clearance than lixisenatide or voglibose-treated diabetic rats without significant change of serum sodium level and fractional excretion of sodium. In empagliflozin-treated rats, renal expression of Na+-Cl- cotransporter was unaltered, and expressions of Na+/H+ exchanger isoform 3, Na+-K+-2Cl- cotransporter, and epithelial Na+ channel were decreased compared with control diabetic rats. Empagliflozin increased an expression of aquaporin (AQP)7 but did not affect AQP3 and AQP1 protein expressions in diabetic kidneys. Despite the increased expression in vasopressin V2 receptor, protein and mRNA levels of AQP2 in empagliflozin-treated diabetic kidneys were significantly decreased compared to control diabetic kidneys. In addition, empagliflozin resulted in the increased phosphorylation of AQP2 at S261 through the increased cyclin-dependent kinases 1 and 5 and protein phosphatase 2B. These results suggest that empagliflozin may contribute in part to polyuria via its regulation of sodium channels and AQP2 in diabetic kidneys.
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Affiliation(s)
- Sungjin Chung
- Division of Nephrology, Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Seoul, South Korea
| | - Soojeong Kim
- Department of Biochemistry, College of Medicine, The Catholic University of Korea, Seoul, South Korea
| | - Mina Son
- Division of Nephrology, Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Seoul, South Korea
| | - Minyoung Kim
- Division of Nephrology, Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Seoul, South Korea
| | - Eun Sil Koh
- Division of Nephrology, Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Seoul, South Korea
| | - Seok Joon Shin
- Division of Nephrology, Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Seoul, South Korea
| | - Seung-Hyun Ko
- Division of Endocrinology, Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Seoul, South Korea
| | - Ho-Shik Kim
- Department of Biochemistry, College of Medicine, The Catholic University of Korea, Seoul, South Korea
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Swanson EA, Nelson JW, Jeng S, Erspamer KJ, Yang CL, McWeeney S, Ellison DH. Salt-sensitive transcriptome of isolated kidney distal tubule cells. Physiol Genomics 2019; 51:125-135. [PMID: 30875275 DOI: 10.1152/physiolgenomics.00119.2018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
In the distal kidney tubule, the steroid hormone aldosterone regulates sodium reabsorption via the epithelial sodium channel (ENaC). Most studies seeking to identify ENaC-regulating aldosterone-induced proteins have used transcriptional profiling of cultured cells. To identify salt-sensitive transcripts in an in vivo model, we used low-NaCl or high-NaCl diet to stimulate or suppress endogenous aldosterone, in combination with magnetic- and fluorescence-activated cell sorting to isolate distal tubule cells from mouse kidney for transcriptional profiling. Of the differentially expressed transcripts, 162 were more abundant in distal tubule cells isolated from mice fed low-NaCl diet, and 161 were more abundant in distal tubule cells isolated from mice fed high-NaCl diet. Enrichment analysis of Gene Ontology biological process terms identified multiple statistically overrepresented pathways among the differentially expressed transcripts that were more abundant in distal tubule cells isolated from mice fed low-NaCl diet, including ion transmembrane transport, regulation of growth, and negative regulation of apoptosis. Analysis of Gene Ontology molecular function terms identified differentially expressed transcription factors, transmembrane transporters, kinases, and G protein-coupled receptors. Finally, comparison with a recently published study of gene expression changes in distal tubule cells in response to administration of aldosterone identified 18 differentially expressed genes in common between the two experiments. When expression of these genes was measured in cortical collecting ducts microdissected from mice fed low-NaCl or high-NaCl diet, eight were differentially expressed. These genes are likely to be regulated directly by aldosterone and may provide insight into aldosterone signaling to ENaC in the distal tubule.
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Affiliation(s)
- Elizabeth A Swanson
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health & Science University , Portland, Oregon
| | - Jonathan W Nelson
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health & Science University , Portland, Oregon
| | - Sophia Jeng
- Division of Bioinformatics & Computational Biology, Department of Medical Informatics and Clinical Epidemiology, Oregon Health & Science University , Portland, Oregon
| | - Kayla J Erspamer
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health & Science University , Portland, Oregon
| | - Chao-Ling Yang
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health & Science University , Portland, Oregon
| | - Shannon McWeeney
- Division of Bioinformatics & Computational Biology, Department of Medical Informatics and Clinical Epidemiology, Oregon Health & Science University , Portland, Oregon.,Oregon Clinical & Translational Research Institute, Oregon Health & Science University , Portland, Oregon
| | - David H Ellison
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health & Science University , Portland, Oregon.,Oregon Clinical & Translational Research Institute, Oregon Health & Science University , Portland, Oregon.,Renal Section, Portland VA Medical Center , Portland, Oregon
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42
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Zheng X, Asico LD, Ma X, Konkalmatt PR. G protein-coupled receptor 37L1 regulates renal sodium transport and blood pressure. Am J Physiol Renal Physiol 2018; 316:F506-F516. [PMID: 30566002 DOI: 10.1152/ajprenal.00289.2018] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
G protein-coupled receptors (GPCRs) in the kidney regulate the reabsorption of essential nutrients, ions, and water from the glomerular filtrate. Abnormalities in renal epithelial ion transport play important roles in the pathogenesis of essential hypertension. The orphan G protein-coupled receptor 37L1 (GPR37L1), also known as endothelin receptor type B-like protein (ETBR-LP2), is expressed in several regions in the brain, but its expression profile and function in peripheral tissues are poorly understood. We found that GPR37L1 mRNA expression is highest in the brain, followed by the stomach, heart, testis, and ovary, with moderate expression in the kidney, pancreas, skeletal muscle, liver, lung, and spleen. Immunofluorescence analyses revealed the expression of GPR37L1 in specific regions within some organs. In the kidney, GPR37L1 is expressed in the apical membrane of renal proximal tubule cells. In human renal proximal tubule cells, the transient expression of GPR37LI increased intracellular sodium, whereas the silencing of GPR37LI decreased intracellular sodium. Inhibition of Na+/H+ exchanger isoform 3 (NHE3) activity abrogated the GPR37L1-mediated increase in intracellular sodium. Renal-selective silencing of Gpr37l1 in mice increased urine output and sodium excretion and decreased systolic and diastolic blood pressures. The renal-selective silencing of GPR37L1 decreased the protein expression of NHE3 but not the expression of Na+-K+-ATPase or sodium-glucose cotransporter 2. Our findings show that in the kidney, GPR37L1 participates in renal proximal tubule luminal sodium transport and regulation of blood pressure by increasing the renal expression and function of NHE3 by decreasing cAMP production. The role of GPR37L1, expressed in specific cell types in organs other than the kidney, remains to be determined.
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Affiliation(s)
- Xiaoxu Zheng
- Department of Medicine, The George Washington University , Washington, District of Columbia
| | - Laureano D Asico
- Department of Medicine, The George Washington University , Washington, District of Columbia
| | - Xiaobo Ma
- Department of Medicine, The George Washington University , Washington, District of Columbia
| | - Prasad R Konkalmatt
- Department of Medicine, The George Washington University , Washington, District of Columbia
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43
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Shalaeva DN, Cherepanov DA, Galperin MY, Golovin AV, Mulkidjanian AY. Evolution of cation binding in the active sites of P-loop nucleoside triphosphatases in relation to the basic catalytic mechanism. eLife 2018; 7:e37373. [PMID: 30526846 PMCID: PMC6310460 DOI: 10.7554/elife.37373] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Accepted: 11/26/2018] [Indexed: 01/01/2023] Open
Abstract
The ubiquitous P-loop fold nucleoside triphosphatases (NTPases) are typically activated by an arginine or lysine 'finger'. Some of the apparently ancestral NTPases are, instead, activated by potassium ions. To clarify the activation mechanism, we combined comparative structure analysis with molecular dynamics (MD) simulations of Mg-ATP and Mg-GTP complexes in water and in the presence of potassium, sodium, or ammonium ions. In all analyzed structures of diverse P-loop NTPases, the conserved P-loop motif keeps the triphosphate chain of bound NTPs (or their analogs) in an extended, catalytically prone conformation, similar to that imposed on NTPs in water by potassium or ammonium ions. MD simulations of potassium-dependent GTPase MnmE showed that linking of alpha- and gamma phosphates by the activating potassium ion led to the rotation of the gamma-phosphate group yielding an almost eclipsed, catalytically productive conformation of the triphosphate chain, which could represent the basic mechanism of hydrolysis by P-loop NTPases.
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Affiliation(s)
- Daria N Shalaeva
- School of PhysicsUniversity of OsnabrückOsnabrückGermany
- A.N. Belozersky Institute of Physico-Chemical BiologyLomonosov Moscow State UniversityMoscowRussia
- School of Bioengineering and BioinformaticsLomonosov Moscow State UniversityMoscowRussia
| | - Dmitry A Cherepanov
- A.N. Belozersky Institute of Physico-Chemical BiologyLomonosov Moscow State UniversityMoscowRussia
- Semenov Institute of Chemical PhysicsRussian Academy of SciencesMoscowRussia
| | - Michael Y Galperin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of HealthBethesdaUnited States
| | - Andrey V Golovin
- School of Bioengineering and BioinformaticsLomonosov Moscow State UniversityMoscowRussia
| | - Armen Y Mulkidjanian
- School of PhysicsUniversity of OsnabrückOsnabrückGermany
- A.N. Belozersky Institute of Physico-Chemical BiologyLomonosov Moscow State UniversityMoscowRussia
- School of Bioengineering and BioinformaticsLomonosov Moscow State UniversityMoscowRussia
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44
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Roenn CP, Li M, Schack VR, Forster IC, Holm R, Toustrup-Jensen MS, Andersen JP, Petrou S, Vilsen B. Functional consequences of the CAPOS mutation E818K of Na +,K +-ATPase. J Biol Chem 2018; 294:269-280. [PMID: 30409907 DOI: 10.1074/jbc.ra118.004591] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Revised: 11/04/2018] [Indexed: 11/06/2022] Open
Abstract
The cerebellar ataxia, areflexia, pes cavus, optic atrophy, and sensorineural hearing loss (CAPOS) syndrome is caused by the single mutation E818K of the α3-isoform of Na+,K+-ATPase. Here, using biochemical and electrophysiological approaches, we examined the functional characteristics of E818K, as well as of E818Q and E818A mutants. We found that these amino acid substitutions reduce the apparent Na+ affinity at the cytoplasmic-facing sites of the pump protein and that this effect is more pronounced for the lysine and glutamine substitutions (3-4-fold) than for the alanine substitution. The electrophysiological measurements indicated a more conspicuous, ∼30-fold reduction of apparent Na+ affinity for the extracellular-facing sites in the CAPOS mutant, which was related to an accelerated transition between the phosphoenzyme intermediates E1P and E2P. The apparent affinity for K+ activation of the ATPase activity was unaffected by these substitutions, suggesting that primarily the Na+-specific site III is affected. Furthermore, the apparent affinities for ATP and vanadate were WT-like in E818K, indicating a normal E1-E2 equilibrium of the dephosphoenzyme. Proton-leak currents were not increased in E818K. However, the CAPOS mutation caused a weaker voltage dependence of the pumping rate and a stronger inhibition by cytoplasmic K+ than the WT enzyme, which together with the reduced Na+ affinity of the cytoplasmic-facing sites precluded proper pump activation under physiological conditions. The functional deficiencies could be traced to the participation of Glu-818 in an intricate hydrogen-bonding/salt-bridge network, connecting it to key residues involved in Na+ interaction at site III.
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Affiliation(s)
- Christian P Roenn
- Department of Biomedicine, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Melody Li
- Florey Institute of Neuroscience and Mental Health, Parkville, 3052 Victoria, Australia
| | - Vivien R Schack
- Department of Biomedicine, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Ian C Forster
- Florey Institute of Neuroscience and Mental Health, Parkville, 3052 Victoria, Australia
| | - Rikke Holm
- Department of Biomedicine, Aarhus University, DK-8000 Aarhus C, Denmark
| | | | - Jens P Andersen
- Department of Biomedicine, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Steven Petrou
- Florey Institute of Neuroscience and Mental Health, Parkville, 3052 Victoria, Australia
| | - Bente Vilsen
- Department of Biomedicine, Aarhus University, DK-8000 Aarhus C, Denmark.
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Sun J, Cao H, Cheng J, He X, Sohail H, Niu M, Huang Y, Bie Z. Pumpkin CmHKT1;1 Controls Shoot Na⁺ Accumulation via Limiting Na⁺ Transport from Rootstock to Scion in Grafted Cucumber. Int J Mol Sci 2018; 19:E2648. [PMID: 30200653 PMCID: PMC6165489 DOI: 10.3390/ijms19092648] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Revised: 09/03/2018] [Accepted: 09/04/2018] [Indexed: 01/09/2023] Open
Abstract
Soil salinity adversely affects the growth and yield of crops, including cucumber, one of the most important vegetables in the world. Grafting with salt-tolerant pumpkin as the rootstock effectively improves the growth of cucumber under different salt conditions by limiting Na⁺ transport from the pumpkin rootstock to the cucumber scion. High-affinity potassium transporters (HKTs) are crucial for the long distance transport of Na⁺ in plants, but the function of pumpkin HKTs in this process of grafted cucumber plants remains unclear. In this work, we have characterized CmHKT1;1 as a member of the HKT gene family in Cucurbita moschata and observed an obvious upregulation of CmHKT1;1 in roots under NaCl stress conditions. Heterologous expression analyses in yeast mutants indicated that CmHKT1;1 is a Na⁺-selective transporter. The transient expression in tobacco epidermal cells and in situ hybridization showed CmHKT1;1 localization at plasma membrane, and preferential expression in root stele. Moreover, ectopic expression of CmHKT1;1 in cucumber decreased the Na⁺ accumulation in the plants shoots. Finally, the CmHKT1;1 transgenic line as the rootstock decreased the Na⁺ content in the wild type shoots. These findings suggest that CmHKT1;1 plays a key role in the salt tolerance of grafted cucumber by limiting Na⁺ transport from the rootstock to the scion and can further be useful for engineering salt tolerance in cucurbit crops.
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Affiliation(s)
- Jingyu Sun
- Key Laboratory of Horticultural Plant Biology, Ministry of Education, College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan 430070, China.
| | - Haishun Cao
- Key Laboratory of Horticultural Plant Biology, Ministry of Education, College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan 430070, China.
| | - Jintao Cheng
- Key Laboratory of Horticultural Plant Biology, Ministry of Education, College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan 430070, China.
| | - Xiaomeng He
- Key Laboratory of Horticultural Plant Biology, Ministry of Education, College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan 430070, China.
| | - Hamza Sohail
- Key Laboratory of Horticultural Plant Biology, Ministry of Education, College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan 430070, China.
| | - Mengliang Niu
- Key Laboratory of Horticultural Plant Biology, Ministry of Education, College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan 430070, China.
| | - Yuan Huang
- Key Laboratory of Horticultural Plant Biology, Ministry of Education, College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan 430070, China.
| | - Zhilong Bie
- Key Laboratory of Horticultural Plant Biology, Ministry of Education, College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan 430070, China.
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Ramkumar N, Stuart D, Mironova E, Abraham N, Gao Y, Wang S, Lakshmipathi J, Stockand JD, Kohan DE. Collecting duct principal, but not intercalated, cell prorenin receptor regulates renal sodium and water excretion. Am J Physiol Renal Physiol 2018; 315:F607-F617. [PMID: 29790390 PMCID: PMC6172572 DOI: 10.1152/ajprenal.00122.2018] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Revised: 05/09/2018] [Accepted: 05/14/2018] [Indexed: 12/21/2022] Open
Abstract
The collecting duct is the predominant nephron site of prorenin and prorenin receptor (PRR) expression. We previously demonstrated that the collecting duct PRR regulates epithelial Na+ channel (ENaC) activity and water transport; however, which cell type is involved remains unclear. Herein, we examined the effects of principal cell (PC) or intercalated cell (IC) PRR deletion on renal Na+ and water handling. PC or IC PRR knockout (KO) mice were obtained by crossing floxed PRR mice with mice harboring Cre recombinase under the control of the AQP2 or B1 subunit of the H+ ATPase promoters, respectively. PC KO mice had reduced renal medullary ENaC-α abundance and increased urinary Na+ losses on a low-Na+ diet compared with controls. Conversely, IC KO mice had no apparent differences in Na+ balance or ENaC abundance compared with controls. Acute treatment with prorenin increased ENaC channel number and open probability in acutely isolated cortical collecting ducts from control and IC PRR KO, but not PC PRR KO, mice. Furthermore, compared with controls, PC KO, but not IC KO mice, had increased urine volume, reduced urine osmolality, and reduced abundance of renal medullary AQP2. Taken together, these findings indicate that PC, but not IC, PRR modulates ENaC activity, urinary Na+ excretion, and water transport.
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Affiliation(s)
- Nirupama Ramkumar
- Division of Nephrology and Hypertension, University of Utah Health Sciences Center , Salt Lake City, Utah
| | - Deborah Stuart
- Division of Nephrology and Hypertension, University of Utah Health Sciences Center , Salt Lake City, Utah
| | - Elena Mironova
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center , San Antonio, Texas
| | - Nikita Abraham
- Division of Nephrology and Hypertension, University of Utah Health Sciences Center , Salt Lake City, Utah
| | - Yang Gao
- Division of Nephrology and Hypertension, University of Utah Health Sciences Center , Salt Lake City, Utah
| | - Shuping Wang
- Division of Nephrology and Hypertension, University of Utah Health Sciences Center , Salt Lake City, Utah
| | - Jayalakshmi Lakshmipathi
- Division of Nephrology and Hypertension, University of Utah Health Sciences Center , Salt Lake City, Utah
| | - James D Stockand
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center , San Antonio, Texas
| | - Donald E Kohan
- Division of Nephrology and Hypertension, University of Utah Health Sciences Center , Salt Lake City, Utah
- Department of Veterans Affairs Medical Center , Salt Lake City, Utah
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47
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Li Q, McDonough AA, Layton HE, Layton AT. Functional implications of sexual dimorphism of transporter patterns along the rat proximal tubule: modeling and analysis. Am J Physiol Renal Physiol 2018; 315:F692-F700. [PMID: 29846110 PMCID: PMC6172582 DOI: 10.1152/ajprenal.00171.2018] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Revised: 05/14/2018] [Accepted: 05/22/2018] [Indexed: 01/07/2023] Open
Abstract
The goal of this study is to investigate the functional implications of the sexual dimorphism in transporter patterns along the proximal tubule. To do so, we have developed sex-specific computational models of solute and water transport in the proximal convoluted tubule of the rat kidney. The models account for the sex differences in expression levels of the apical and basolateral transporters, in single-nephron glomerular filtration rate, and in tubular dimensions. Model simulations predict that 70.6 and 38.7% of the filtered volume is reabsorbed by the proximal tubule of the male and female rat kidneys, respectively. The lower fractional volume reabsorption in females can be attributed to their smaller transport area and lower aquaporin-1 expression level. The latter also results in a larger contribution of the paracellular pathway to water transport. Correspondingly similar fractions (70.9 and 39.2%) of the filtered Na+ are reabsorbed by the male and female proximal tubule models, respectively. The lower fractional Na+ reabsorption in females is due primarily to their smaller transport area and lower Na+/H+ exchanger isoform 3 and claudin-2 expression levels. Notably, unlike most Na+ transporters, whose expression levels are lower in females, Na+-glucose cotransporter 2 (SGLT2) expression levels are 2.5-fold higher in females. Model simulations suggest that the higher SGLT2 expression in females may compensate for their lower tubular transport area to achieve a hyperglycemic tolerance similar to that of males.
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Affiliation(s)
- Qianyi Li
- Kuang Yaming Honors School, Nanjing University , Nanjing , China
| | - Alicia A McDonough
- Department of Integrative Anatomical Sciences, Kerck School of Medicine, University of Southern California , Los Angeles, California
| | - Harold E Layton
- Department of Mathematics, Duke University , Durham, North Carolina
| | - Anita T Layton
- Department of Mathematics, Duke University , Durham, North Carolina
- Departments of Biomedical Engineering and Medicine, Duke University , Durham, North Carolina
- Department of Applied Mathematics, University of Waterloo , Waterloo, Ontario , Canada
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48
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Ho PY, Li H, Pavlov TS, Tuerk RD, Tabares D, Brunisholz R, Neumann D, Staruschenko A, Hallows KR. β 1Pix exchange factor stabilizes the ubiquitin ligase Nedd4-2 and plays a critical role in ENaC regulation by AMPK in kidney epithelial cells. J Biol Chem 2018; 293:11612-11624. [PMID: 29858246 DOI: 10.1074/jbc.ra118.003082] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Revised: 05/22/2018] [Indexed: 12/22/2022] Open
Abstract
Our previous work has established that the metabolic sensor AMP-activated protein kinase (AMPK) inhibits the epithelial Na+ channel (ENaC) by promoting its binding to neural precursor cell-expressed, developmentally down-regulated 4-2, E3 ubiquitin protein ligase (Nedd4-2). Here, using MS analysis and in vitro phosphorylation, we show that AMPK phosphorylates Nedd4-2 at the Ser-444 (Xenopus Nedd4-2) site critical for Nedd4-2 stability. We further demonstrate that the Pak-interacting exchange factor β1Pix is required for AMPK-mediated inhibition of ENaC-dependent currents in both CHO and murine kidney cortical collecting duct (CCD) cells. Short hairpin RNA-mediated knockdown of β1Pix expression in CCD cells attenuated the inhibitory effect of AMPK activators on ENaC currents. Moreover, overexpression of a β1Pix dimerization-deficient mutant unable to bind 14-3-3 proteins (Δ602-611) increased ENaC currents in CCD cells, whereas overexpression of WT β1Pix had the opposite effect. Using additional immunoblotting and co-immunoprecipitation experiments, we found that treatment with AMPK activators promoted the binding of β1Pix to 14-3-3 proteins in CCD cells. However, the association between Nedd4-2 and 14-3-3 proteins was not consistently affected by AMPK activation, β1Pix knockdown, or overexpression of WT β1Pix or the β1Pix-Δ602-611 mutant. Moreover, we found that β1Pix is important for phosphorylation of the aforementioned Nedd4-2 site critical for its stability. Overall, these findings elucidate novel molecular mechanisms by which AMPK regulates ENaC. Specifically, they indicate that AMPK promotes the assembly of β1Pix, 14-3-3 proteins, and Nedd4-2 into a complex that inhibits ENaC by enhancing Nedd4-2 binding to ENaC and its degradation.
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Affiliation(s)
- Pei-Yin Ho
- Division of Nephrology and Hypertension, Department of Medicine and USC/UKRO Kidney Research Center, Keck School of Medicine, University of Southern California, Los Angeles, California 90033
| | - Hui Li
- Division of Nephrology and Hypertension, Department of Medicine and USC/UKRO Kidney Research Center, Keck School of Medicine, University of Southern California, Los Angeles, California 90033
| | - Tengis S Pavlov
- the Division of Hypertension and Vascular Research, Henry Ford Health System, Detroit, Michigan 48202; Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226
| | - Roland D Tuerk
- Department of Biology, Institute of Cell Biology, ETH Zurich, 8093 Zurich, Switzerland
| | - Diego Tabares
- Division of Nephrology and Hypertension, Department of Medicine and USC/UKRO Kidney Research Center, Keck School of Medicine, University of Southern California, Los Angeles, California 90033
| | - René Brunisholz
- Functional Genomics Center, ETH Zurich, 8097 Zurich, Switzerland
| | - Dietbert Neumann
- Department of Biology, Institute of Cell Biology, ETH Zurich, 8093 Zurich, Switzerland; Department of Pathology, School for Cardiovascular Diseases, Maastricht University, 6200 MD Maastricht, The Netherlands
| | | | - Kenneth R Hallows
- Division of Nephrology and Hypertension, Department of Medicine and USC/UKRO Kidney Research Center, Keck School of Medicine, University of Southern California, Los Angeles, California 90033.
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49
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Puga Molina LC, Pinto NA, Torres NI, González-Cota AL, Luque GM, Balestrini PA, Romarowski A, Krapf D, Santi CM, Treviño CL, Darszon A, Buffone MG. CFTR/ENaC-dependent regulation of membrane potential during human sperm capacitation is initiated by bicarbonate uptake through NBC. J Biol Chem 2018; 293:9924-9936. [PMID: 29743243 DOI: 10.1074/jbc.ra118.003166] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Revised: 04/29/2018] [Indexed: 12/16/2022] Open
Abstract
To fertilize an egg, sperm must reside in the female reproductive tract to undergo several maturational changes that are collectively referred to as capacitation. From a molecular point of view, the HCO3--dependent activation of the atypical soluble adenylyl cyclase (ADCY10) is one of the first events that occurs during capacitation and leads to the subsequent cAMP-dependent activation of protein kinase A (PKA). Capacitation is also accompanied by hyperpolarization of the sperm plasma membrane. We previously reported that PKA activation is necessary for CFTR (cystic fibrosis transmembrane conductance regulator channel) activity and for the modulation of membrane potential (Em). However, the main HCO3- transporters involved in the initial transport and the PKA-dependent Em changes are not well known nor characterized. Here, we analyzed how the activity of CFTR regulates Em during capacitation and examined its relationship with an electrogenic Na+/HCO3- cotransporter (NBC) and epithelial Na+ channels (ENaCs). We observed that inhibition of both CFTR and NBC decreased HCO3- influx, resulting in lower PKA activity, and that events downstream of the cAMP activation of PKA are essential for the regulation of Em. Addition of a permeable cAMP analog partially rescued the inhibitory effects caused by these inhibitors. HCO3- also produced a rapid membrane hyperpolarization mediated by ENaC channels, which contribute to the regulation of Em during capacitation. Altogether, we demonstrate for the first time, that NBC cotransporters and ENaC channels are essential in the CFTR-dependent activation of the cAMP/PKA signaling pathway and Em regulation during human sperm capacitation.
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Affiliation(s)
- Lis C Puga Molina
- From the Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), C1425FQB Buenos Aires, Argentina
| | - Nicolás A Pinto
- From the Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), C1425FQB Buenos Aires, Argentina
| | - Nicolás I Torres
- From the Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), C1425FQB Buenos Aires, Argentina
| | - Ana L González-Cota
- the Department of Obstetrics and Gynecology, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Guillermina M Luque
- From the Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), C1425FQB Buenos Aires, Argentina
| | - Paula A Balestrini
- From the Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), C1425FQB Buenos Aires, Argentina
| | - Ana Romarowski
- From the Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), C1425FQB Buenos Aires, Argentina
| | - Dario Krapf
- the Instituto de Biología Molecular y Celular de Rosario (IBR), CONICET-UNR, Rosario 2000, Argentina, and
| | - Celia M Santi
- the Department of Obstetrics and Gynecology, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Claudia L Treviño
- the Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, 62210 Morelos, México
| | - Alberto Darszon
- the Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, 62210 Morelos, México
| | - Mariano G Buffone
- From the Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), C1425FQB Buenos Aires, Argentina,
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50
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Aw M, Armstrong TM, Nawata CM, Bodine SN, Oh JJ, Wei G, Evans KK, Shahidullah M, Rieg T, Pannabecker TL. Body mass-specific Na +-K +-ATPase activity in the medullary thick ascending limb: implications for species-dependent urine concentrating mechanisms. Am J Physiol Regul Integr Comp Physiol 2018; 314:R563-R573. [PMID: 29351422 DOI: 10.1152/ajpregu.00289.2017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
In general, the mammalian whole body mass-specific metabolic rate correlates positively with maximal urine concentration (Umax) irrespective of whether or not the species have adapted to arid or mesic habitat. Accordingly, we hypothesized that the thick ascending limb (TAL) of a rodent with markedly higher whole body mass-specific metabolism than rat exhibits a substantially higher TAL metabolic rate as estimated by Na+-K+-ATPase activity and Na+-K+-ATPase α1-gene and protein expression. The kangaroo rat inner stripe of the outer medulla exhibits significantly higher mean Na+-K+-ATPase activity (~70%) compared with two rat strains (Sprague-Dawley and Munich-Wistar), extending prior studies showing rat activity exceeds rabbit. Furthermore, higher expression of Na+-K+-ATPase α1-protein (~4- to 6-fold) and mRNA (~13-fold) and higher TAL mitochondrial volume density (~20%) occur in the kangaroo rat compared with both rat strains. Rat TAL Na+-K+-ATPase α1-protein expression is relatively unaffected by body hydration status or, shown previously, by dietary Na+, arguing against confounding effects from two unavoidably dissimilar diets: grain-based diet without water (kangaroo rat) or grain-based diet with water (rat). We conclude that higher TAL Na+-K+-ATPase activity contributes to relationships between whole body mass-specific metabolic rate and high Umax. More vigorous TAL Na+-K+-ATPase activity in kangaroo rat than rat may contribute to its steeper Na+ and urea axial concentration gradients, adding support to a revised model of the urine concentrating mechanism, which hypothesizes a leading role for vigorous active transport of NaCl, rather than countercurrent multiplication, in generating the outer medullary axial osmotic gradient.
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Affiliation(s)
- Mun Aw
- Department of Physiology, Banner-University Medical Center, University of Arizona , Tucson, Arizona
| | - Tamara M Armstrong
- Department of Physiology, Banner-University Medical Center, University of Arizona , Tucson, Arizona
| | - C Michele Nawata
- Department of Physiology, Banner-University Medical Center, University of Arizona , Tucson, Arizona
| | - Sarah N Bodine
- Department of Physiology, Banner-University Medical Center, University of Arizona , Tucson, Arizona
| | - Jeeeun J Oh
- Department of Physiology, Banner-University Medical Center, University of Arizona , Tucson, Arizona
| | - Guojun Wei
- Department of Physiology, Banner-University Medical Center, University of Arizona , Tucson, Arizona
| | - Kristen K Evans
- Department of Physiology, Banner-University Medical Center, University of Arizona , Tucson, Arizona
| | - Mohammad Shahidullah
- Department of Physiology, Banner-University Medical Center, University of Arizona , Tucson, Arizona
| | - Timo Rieg
- Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida , Tampa, Florida
| | - Thomas L Pannabecker
- Department of Physiology, Banner-University Medical Center, University of Arizona , Tucson, Arizona
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