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Zhang M, Liu M, Wang W, Ren Z, Wang P, Xue Y, Wang X. The salt sensitivity of Drd4-null mice is associated with the upregulations of sodium transporters in kidneys. Hypertens Res 2024:10.1038/s41440-024-01724-5. [PMID: 38778170 DOI: 10.1038/s41440-024-01724-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2024] [Revised: 04/01/2024] [Accepted: 04/21/2024] [Indexed: 05/25/2024]
Abstract
To explore the mechanism of the hypertension in dopamine receptor-4 (Drd4) null mice, we determined the salt sensitivity and renal sodium transport proteins in Drd4-/- and Drd4+/+ mice with varied salt diets. On normal NaCl diet (NS), mean arterial pressures (MAP, telemetry) were higher in Drd4-/- than Drd4+/+; Low NaCl diet (LS) tended to decrease MAP in both strains; high NaCl diet (HS) elevated MAP with sodium excretion decreased and pressure-natriuresis curve shifted to right in Drd4-/- relative to Drd4+/+ mice. Drd4-/- mice exhibited increased renal sodium-hydrogen exchanger 3 (NHE3), sodium-potassium-2-chloride cotransporter (NKCC2), sodium-chloride cotransporter (NCC), and outer medullary α-epithelial sodium channel (αENaC) on NS, decreased NKCC2, NCC, αENaC, and αNa+-K+-ATPase on LS, and increased αENaC on HS. NKCC2, NCC, αENaC, and αNa+-K+-ATPase in plasma membrane were greater in Drd4-/- than in Drd4+/+ mice with HS. D4R was expressed in proximal and distal convoluted tubules, thick ascending limbs, and outer medullary collecting ducts and colocalized with NKCC2 and NCC. The phosphorylation of NKCC2 was enhanced but ubiquitination was reduced in the KO mice. There were no differences between the mouse strains in serum aldosterone concentrations and urinary dopamine excretions despite their changes with diets. The mRNA expressions of renal NHE3, NKCC2, NCC, and αENaC on NS were not altered in Drd4-/- mice. Thus, increased protein expressions of NHE3, NKCC2, NCC and αENaC are associated with hypertension in Drd4-/- mice; increased plasma membrane protein expression of NKCC2, NCC, αENaC, and αNa+-K+-ATPase may mediate the salt sensitivity of Drd4-/- mice.
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Affiliation(s)
- Mingzhuo Zhang
- The Core Laboratory for Clinical Research, BenQ Medical Center, The Affiliated BenQ Hospital of Nanjing Medical University, Nanjing, China
- Department of Nephrology, BenQ Medical Center, The Affiliated BenQ Hospital of Nanjing Medical University, Nanjing, China
| | - Mingda Liu
- The Core Laboratory for Clinical Research, BenQ Medical Center, The Affiliated BenQ Hospital of Nanjing Medical University, Nanjing, China
| | - Weiwan Wang
- The Core Laboratory for Clinical Research, BenQ Medical Center, The Affiliated BenQ Hospital of Nanjing Medical University, Nanjing, China
| | - Zhiyun Ren
- The Core Laboratory for Clinical Research, BenQ Medical Center, The Affiliated BenQ Hospital of Nanjing Medical University, Nanjing, China
| | - Ping Wang
- The Core Laboratory for Clinical Research, BenQ Medical Center, The Affiliated BenQ Hospital of Nanjing Medical University, Nanjing, China
| | - Ying Xue
- The Core Laboratory for Clinical Research, BenQ Medical Center, The Affiliated BenQ Hospital of Nanjing Medical University, Nanjing, China
| | - Xiaoyan Wang
- The Core Laboratory for Clinical Research, BenQ Medical Center, The Affiliated BenQ Hospital of Nanjing Medical University, Nanjing, China.
- Department of Nephrology, BenQ Medical Center, The Affiliated BenQ Hospital of Nanjing Medical University, Nanjing, China.
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Fan Y, Wang H, Yu Z, Liang Z, Li Y, You G. Inhibition of proteasome, but not lysosome, upregulates organic anion transporter 3 in vitro and in vivo. Biochem Pharmacol 2023; 208:115387. [PMID: 36549459 PMCID: PMC9877193 DOI: 10.1016/j.bcp.2022.115387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2022] [Revised: 12/10/2022] [Accepted: 12/14/2022] [Indexed: 12/23/2022]
Abstract
Organic anion transporter 3 (OAT3), an indispensable basolateral membrane transporter predominantly distributed in the kidney proximal tubules, mediated the systemic clearance of substrates including clinical drugs, nutrients, endogenous and exogenous metabolites, toxins, and critically sustains body homeostasis. Preliminary data in this study showed that classical proteasome inhibitors (e.g., MG132), but not lysosome inhibitors, significantly increased the OAT3 ubiquitination and OAT3-mediated transport of estrone sulfate (ES) in OAT3 stable expressing cells, indicating that proteasome rather than lysosome is involved in the intracellular fate of OAT3. Next, bortezomib and carfilzomib, two FDA-approved and widely applied anticancer agents through selective targeting proteasome, were further used to define the role of inhibiting proteasome in OAT3 regulation and related molecular mechanisms. The results showed that 20S proteasome activity in cell lysates was suppressed with bortezomib and carfilzomib treatment, leading to the increased OAT3 ubiquitination, stimulated transport activity of ES, enhanced OAT3 surface and total expression. The upregulated OAT3 function by proteasome inhibition was attributed to the augment in maximum transport velocity and stability of membrane OAT3. Lastly, in vivo study using Sprague Dawley rats validated that proteasome inhibition using bortezomib induced enhancement of OAT3 ubiquitination and membrane expression in kidney. These data suggest that activity of proteasome but not lysosome could have an impact on the physiological function of OAT3, and proteasome displayed a promising target for OAT3 regulation in vitro and in vivo, and could be used in restoring OAT3 impairment under pathological conditions, avoiding OAT3-associated toxicity and diseases, ensuring drug efficacy and safety.
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Affiliation(s)
- Yunzhou Fan
- Department of Pharmaceutics, Rutgers, The State University of New Jersey, Piscataway, NJ, USA
| | - Haoxun Wang
- Department of Pharmaceutics, Rutgers, The State University of New Jersey, Piscataway, NJ, USA
| | - Zhou Yu
- Department of Pharmaceutics, Rutgers, The State University of New Jersey, Piscataway, NJ, USA
| | - Zhengxuan Liang
- Department of Pharmaceutics, Rutgers, The State University of New Jersey, Piscataway, NJ, USA
| | - Yufan Li
- Department of Pharmaceutics, Rutgers, The State University of New Jersey, Piscataway, NJ, USA
| | - Guofeng You
- Department of Pharmaceutics, Rutgers, The State University of New Jersey, Piscataway, NJ, USA.
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Nikolovska K, Seidler UE, Stock C. The Role of Plasma Membrane Sodium/Hydrogen Exchangers in Gastrointestinal Functions: Proliferation and Differentiation, Fluid/Electrolyte Transport and Barrier Integrity. Front Physiol 2022; 13:899286. [PMID: 35665228 PMCID: PMC9159811 DOI: 10.3389/fphys.2022.899286] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Accepted: 04/19/2022] [Indexed: 12/11/2022] Open
Abstract
The five plasma membrane Na+/H+ exchanger (NHE) isoforms in the gastrointestinal tract are characterized by distinct cellular localization, tissue distribution, inhibitor sensitivities, and physiological regulation. NHE1 (Slc9a1) is ubiquitously expressed along the gastrointestinal tract in the basolateral membrane of enterocytes, but so far, an exclusive role for NHE1 in enterocyte physiology has remained elusive. NHE2 (Slc9a2) and NHE8 (Slc9a8) are apically expressed isoforms with ubiquitous distribution along the colonic crypt axis. They are involved in pHi regulation of intestinal epithelial cells. Combined use of a knockout mouse model, intestinal organoid technology, and specific inhibitors revealed previously unrecognized actions of NHE2 and NHE8 in enterocyte proliferation and differentiation. NHE3 (Slc9a3), expressed in the apical membrane of differentiated intestinal epithelial cells, functions as the predominant nutrient-independent Na+ absorptive mechanism in the gut. The new selective NHE3 inhibitor (Tenapanor) allowed discovery of novel pathophysiological and drug-targetable NHE3 functions in cystic-fibrosis associated intestinal obstructions. NHE4, expressed in the basolateral membrane of parietal cells, is essential for parietal cell integrity and acid secretory function, through its role in cell volume regulation. This review focuses on the expression, regulation and activity of the five plasma membrane Na+/H+ exchangers in the gastrointestinal tract, emphasizing their role in maintaining intestinal homeostasis, or their impact on disease pathogenesis. We point to major open questions in identifying NHE interacting partners in central cellular pathways and processes and the necessity of determining their physiological role in a system where their endogenous expression/activity is maintained, such as organoids derived from different parts of the gastrointestinal tract.
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Han Y, Yun CC. Metformin Inhibits Na +/H + Exchanger NHE3 Resulting in Intestinal Water Loss. Front Physiol 2022; 13:867244. [PMID: 35444557 PMCID: PMC9014215 DOI: 10.3389/fphys.2022.867244] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 03/07/2022] [Indexed: 11/14/2022] Open
Abstract
Glycemic control is the key to the management of type 2 diabetes. Metformin is an effective, widely used drug for controlling plasma glucose levels in diabetes, but it is often the culprit of gastrointestinal adverse effects such as abdominal pain, nausea, indigestion, vomiting, and diarrhea. Diarrhea is a complex disease and altered intestinal transport of electrolytes and fluid is a common cause of diarrhea. Na+/H+ exchanger 3 (NHE3, SLC9A3) is the major Na+ absorptive mechanism in the intestine and our previous study has demonstrated that decreased NHE3 contributes to diarrhea associated with type 1 diabetes. The goal of this study is to investigate whether metformin regulates NHE3 and inhibition of NHE3 contributes to metformin-induced diarrhea. We first determined whether metformin alters intestinal water loss, the hallmark of diarrhea, in type 2 diabetic db/db mice. We found that metformin decreased intestinal water absorption mediated by NHE3. Metformin increased fecal water content although mice did not develop watery diarrhea. To determine the mechanism of metformin-mediated regulation of NHE3, we used intestinal epithelial cells. Metformin inhibited NHE3 activity and the effect of metformin on NHE3 was mimicked by a 5'-AMP-activated protein kinase (AMPK) activator and blocked by pharmacological inhibition of AMPK. Metformin increased phosphorylation and ubiquitination of NHE3, resulting in retrieval of NHE3 from the plasma membrane. Previous studies have demonstrated the role of neural precursor cell expressed, developmentally down-regulated 4-2 (Nedd4-2) in regulation of human NHE3. Silencing of Nedd4-2 mitigated NHE3 inhibition and ubiquitination by metformin. Our findings suggest that metformin-induced diarrhea in type 2 diabetes is in part caused by reduced Na+ and water absorption that is associated with NHE3 inhibition, probably by AMPK.
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Affiliation(s)
- Yiran Han
- Gastroenterology Research, Atlanta Veterans Administration Medical Center, Decatur, GA, United States
- Division of Digestive Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, GA, United States
| | - C. Chris Yun
- Gastroenterology Research, Atlanta Veterans Administration Medical Center, Decatur, GA, United States
- Division of Digestive Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, GA, United States
- Winship Cancer Institute, Emory University School of Medicine, Atlanta, GA, United States
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Jenkin KA, Han Y, Lin S, He P, Yun CC. Nedd4-2-dependent Ubiquitination Potentiates the Inhibition of Human NHE3 by Cholera Toxin and Enteropathogenic Escherichia coli. Cell Mol Gastroenterol Hepatol 2021; 13:695-716. [PMID: 34823064 PMCID: PMC8789535 DOI: 10.1016/j.jcmgh.2021.11.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Revised: 11/12/2021] [Accepted: 11/15/2021] [Indexed: 12/20/2022]
Abstract
BACKGROUND & AIMS Diarrhea is one of the most common illnesses and is often caused by bacterial infection. Recently, we have shown that human Na+/H+ exchanger NHE3 (hNHE3), but not non-human NHE3s, interacts with the E3 ubiquitin ligase Nedd4-2. We hypothesize that this property of hNHE3 contributes to the increased severity of diarrhea in humans. METHODS We used humanized mice expressing hNHE3 in the intestine (hNHE3int) to compare the contribution of hNHE3 and mouse NHE3 to diarrhea induced by cholera toxin (CTX) and enteropathogenic Escherichia coli (EPEC). We measured Na+/H+ exchange activity and fluid absorption. The role of Nedd4-2 on hNHE3 activity and ubiquitination was determined by knockdown in Caco-2bbe cells. The effects of protein kinase A (PKA), the primary mediator of CTX-induced diarrhea, on Nedd4-2 and hNHE3 phosphorylation and their interaction were determined. RESULTS The effects of CTX and EPEC were greater in hNHE3int mice than in control wild-type (WT) mice, resulting in greater inhibition of NHE3 activity and increased fluid accumulation in the intestine, the hallmark of diarrhea. Activation of PKA increased ubiquitination of hNHE3 and enhanced interaction of Nedd4-2 with hNHE3 via phosphorylation of Nedd4-2 at S342. S342A mutation mitigated the Nedd4-2-hNHE3 interaction and blocked PKA-induced inhibition of hNHE3. Unlike non-human NHE3s, inhibition of hNHE3 by PKA is independent of NHE3 phosphorylation, suggesting a distinct mechanism of hNHE3 regulation. CONCLUSIONS The effects of CTX and EPEC on hNHE3 are amplified, and the unique properties of hNHE3 may contribute to diarrheal symptoms occurring in humans.
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Affiliation(s)
- Kayte A. Jenkin
- Division of Digestive Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia,School of Science, Western Sydney University, Campbelltown, NSW 2560, Australia
| | - Yiran Han
- Division of Digestive Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia,Atlanta VA Medical Center, Decatur, Georgia
| | - Songbai Lin
- Division of Digestive Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia,Atlanta VA Medical Center, Decatur, Georgia
| | - Peijian He
- Division of Digestive Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia
| | - C. Chris Yun
- Division of Digestive Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia,Atlanta VA Medical Center, Decatur, Georgia,Winship Cancer Institute, Emory University School of Medicine, Atlanta, Georgia,Correspondence Address correspondence to: Chris Yun, PhD, Division of Digestive Diseases, Emory University School of Medicine, Atlanta, Georgia 30324. fax: (404) 727-5767.
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Fan Y, Liang Z, Zhang J, You G. Oral Proteasomal Inhibitors Ixazomib, Oprozomib, and Delanzomib Upregulate the Function of Organic Anion Transporter 3 (OAT3): Implications in OAT3-Mediated Drug-Drug Interactions. Pharmaceutics 2021; 13:pharmaceutics13030314. [PMID: 33670955 PMCID: PMC7997269 DOI: 10.3390/pharmaceutics13030314] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 02/15/2021] [Accepted: 02/24/2021] [Indexed: 11/16/2022] Open
Abstract
Organic anion transporter 3 (OAT3) is mainly expressed at the basolateral membrane of kidney proximal tubules, and is involved in the renal elimination of various kinds of important drugs, potentially affecting drug efficacy or toxicity. Our laboratory previously reported that ubiquitin modification of OAT3 triggers the endocytosis of OAT3 from the plasma membrane to intracellular endosomes, followed by degradation. Oral anticancer drugs ixazomib, oprozomib, and delanzomib, as proteasomal inhibitors, target the ubiquitin-proteasome system in clinics. Therefore, this study investigated the effects of ixazomib, oprozomib, and delanzomib on the expression and transport activity of OAT3 and elucidated the underlying mechanisms. We showed that all three drugs significantly increased the accumulation of ubiquitinated OAT3, which was consistent with decreased intracellular 20S proteasomal activity; stimulated OAT3-mediated transport of estrone sulfate and p-aminohippuric acid; and increased OAT3 surface expression. The enhanced transport activity and OAT3 expression following drug treatment resulted from an increase in maximum transport velocity of OAT3 without altering the substrate binding affinity, and from a decreased OAT3 degradation. Together, our study discovered a novel role of anticancer agents ixazomib, oprozomib, and delanzomib in upregulating OAT3 function, unveiled the proteasome as a promising target for OAT3 regulation, and provided implication of OAT3-mediated drug-drug interactions, which should be warned against during combination therapies with proteasome inhibitor drugs.
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Pedersen SF, Counillon L. The SLC9A-C Mammalian Na +/H + Exchanger Family: Molecules, Mechanisms, and Physiology. Physiol Rev 2019; 99:2015-2113. [PMID: 31507243 DOI: 10.1152/physrev.00028.2018] [Citation(s) in RCA: 97] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Na+/H+ exchangers play pivotal roles in the control of cell and tissue pH by mediating the electroneutral exchange of Na+ and H+ across cellular membranes. They belong to an ancient family of highly evolutionarily conserved proteins, and they play essential physiological roles in all phyla. In this review, we focus on the mammalian Na+/H+ exchangers (NHEs), the solute carrier (SLC) 9 family. This family of electroneutral transporters constitutes three branches: SLC9A, -B, and -C. Within these, each isoform exhibits distinct tissue expression profiles, regulation, and physiological roles. Some of these transporters are highly studied, with hundreds of original articles, and some are still only rudimentarily understood. In this review, we present and discuss the pioneering original work as well as the current state-of-the-art research on mammalian NHEs. We aim to provide the reader with a comprehensive view of core knowledge and recent insights into each family member, from gene organization over protein structure and regulation to physiological and pathophysiological roles. Particular attention is given to the integrated physiology of NHEs in the main organ systems. We provide several novel analyses and useful overviews, and we pinpoint main remaining enigmas, which we hope will inspire novel research on these highly versatile proteins.
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Affiliation(s)
- S F Pedersen
- Section for Cell Biology and Physiology, Department of Biology, University of Copenhagen, Copenhagen, Denmark; and Université Côte d'Azur, CNRS, Laboratoire de Physiomédecine Moléculaire, LP2M, France, and Laboratories of Excellence Ion Channel Science and Therapeutics, Nice, France
| | - L Counillon
- Section for Cell Biology and Physiology, Department of Biology, University of Copenhagen, Copenhagen, Denmark; and Université Côte d'Azur, CNRS, Laboratoire de Physiomédecine Moléculaire, LP2M, France, and Laboratories of Excellence Ion Channel Science and Therapeutics, Nice, France
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Crajoinas RO, Polidoro JZ, Girardi ACC. The potential role of myosin motor proteins in mediating the subcellular distribution of NHE3 in the renal proximal tubule. Am J Physiol Renal Physiol 2019; 316:F986-F992. [PMID: 30864843 DOI: 10.1152/ajprenal.00577.2018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Isoform 3 of the Na+/H+ exchanger (NHE3) is responsible for the majority of the reabsorption of NaCl, NaHCO3, and, consequently, water in the renal proximal tubule. As such, this transporter plays an essential role in acid-base balance and extracellular fluid volume homeostasis and determining systemic arterial blood pressure levels. NHE3 activity is modulated by a number of mechanisms, including the redistribution of the transporter between the body of the microvilli (where NHE3 is active) and the base of the microvilli (where NHE3 is less active). Although the physiological, pathophysiological, and pharmacological importance of the subcellular distribution of NHE3 has been well established, the exact mechanism whereby NHE3 is translocated along microvilli microdomains of the proximal tubule apical membrane is unknown. Nonmuscle myosin IIA and unconventional myosin VI move cargoes in anterograde and retrograde directions, respectively, and are known to redistribute along with NHE3 in the proximal tubule in response to a variety of natriuretic and antinatriuretic stimuli, including stimulation or inhibition of the renin-angiotensin system, high dietary Na+ intake, and high blood pressure. Therefore, this review aims to discuss the current evidence that suggests a potential role of myosin IIA and myosin VI in mediating the subcellular distribution of NHE3 along the kidney proximal tubule microvilli and their possible contribution in modifying NHE3-mediated Na+ reabsorption under both physiological and pathophysiological conditions.
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Affiliation(s)
- Renato O Crajoinas
- Heart Institute (InCor), University of São Paulo Medical School , São Paulo , Brazil
| | - Juliano Z Polidoro
- Heart Institute (InCor), University of São Paulo Medical School , São Paulo , Brazil
| | - Adriana C C Girardi
- Heart Institute (InCor), University of São Paulo Medical School , São Paulo , Brazil
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Wang F, Chen S, Jiang Y, Zhao Y, Sun L, Zheng B, Chen L, Liu Z, Zheng X, Yi K, Li C, Zhou X. Effects of ammonia on apoptosis and oxidative stress in bovine mammary epithelial cells. Mutagenesis 2019; 33:291-299. [PMID: 30184101 DOI: 10.1093/mutage/gey023] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Accepted: 08/09/2018] [Indexed: 12/21/2022] Open
Abstract
Ammonia, produced mainly from the deamination of amino acids and glutamine, is one of the major toxic components in blood and tissues that may affect bovine health. However, the physiological and pathological roles of ammonia in the mammary glands are not understood clearly. In the present study, the bovine mammary epithelial cell line (MAC-T) was utilised as an in vitro model to determine the effects of ammonia on bovine mammary gland. We demonstrated that ammonia stimulated the production of intracellular reactive oxygen species, decreased mitochondrial membrane potential, interrupted intracellular calcium ion (Ca2+) homeostasis and induced cell apoptosis. Ammonia also significantly reduced cell viability and increased the proportion of apoptotic cells through enhancing the level of p53 phosphorylation and increasing the expressions of BAX, caspase 8, caspase 9, caspase 3. Interestingly, bumetanide, a specific Na+ K+ 2Cl--cotransporter inhibitor, dramatically abolished the damaging effects of ammonia on the cells. These data suggest that ammonia exposure induces apoptosis in bovine mammary epithelial cells via activation of the p53 pathway and the mitochondrial apoptotic pathway, and that these effects involved the Na+ K+ 2Cl--cotransporter.
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Affiliation(s)
- Fengge Wang
- College of Animal Sciences, Jilin University, Changchun, Jilin, P.R. China
| | - Shuxiong Chen
- College of Animal Sciences, Jilin University, Changchun, Jilin, P.R. China
| | - Yanwen Jiang
- College of Animal Sciences, Jilin University, Changchun, Jilin, P.R. China
| | - Yun Zhao
- College of Animal Sciences, Jilin University, Changchun, Jilin, P.R. China
| | - Liting Sun
- College of Animal Sciences, Jilin University, Changchun, Jilin, P.R. China
| | - Biaobiao Zheng
- College of Animal Sciences, Jilin University, Changchun, Jilin, P.R. China
| | - Lu Chen
- College of Animal Sciences, Jilin University, Changchun, Jilin, P.R. China
| | - Zhuo Liu
- College of Animal Sciences, Jilin University, Changchun, Jilin, P.R. China
| | - Xue Zheng
- College of Animal Sciences, Jilin University, Changchun, Jilin, P.R. China
| | - Kangle Yi
- Hunan Institute of Animal and Veterinary Science, Changsha, Hunan, P.R. China
| | - Chunjin Li
- College of Animal Sciences, Jilin University, Changchun, Jilin, P.R. China
| | - Xu Zhou
- College of Animal Sciences, Jilin University, Changchun, Jilin, P.R. China
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Taub M. Gene Level Regulation of Na,K-ATPase in the Renal Proximal Tubule Is Controlled by Two Independent but Interacting Regulatory Mechanisms Involving Salt Inducible Kinase 1 and CREB-Regulated Transcriptional Coactivators. Int J Mol Sci 2018; 19:E2086. [PMID: 30021947 PMCID: PMC6073390 DOI: 10.3390/ijms19072086] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2018] [Revised: 07/13/2018] [Accepted: 07/16/2018] [Indexed: 12/26/2022] Open
Abstract
For many years, studies concerning the regulation of Na,K-ATPase were restricted to acute regulatory mechanisms, which affected the phosphorylation of Na,K-ATPase, and thus its retention on the plasma membrane. However, in recent years, this focus has changed. Na,K-ATPase has been established as a signal transducer, which becomes part of a signaling complex as a consequence of ouabain binding. Na,K-ATPase within this signaling complex is localized in caveolae, where Na,K-ATPase has also been observed to regulate Inositol 1,4,5-Trisphosphate Receptor (IP3R)-mediated calcium release. This latter association has been implicated as playing a role in signaling by G Protein Coupled Receptors (GPCRs). Here, the consequences of signaling by renal effectors that act via such GPCRs are reviewed, including their regulatory effects on Na,K-ATPase gene expression in the renal proximal tubule (RPT). Two major types of gene regulation entail signaling by Salt Inducible Kinase 1 (SIK1). On one hand, SIK1 acts so as to block signaling via cAMP Response Element (CRE) Binding Protein (CREB) Regulated Transcriptional Coactivators (CRTCs) and on the other hand, SIK1 acts so as to stimulate signaling via the Myocyte Enhancer Factor 2 (MEF2)/nuclear factor of activated T cell (NFAT) regulated genes. Ultimate consequences of these pathways include regulatory effects which alter the rate of transcription of the Na,K-ATPase β1 subunit gene atp1b1 by CREB, as well as by MEF2/NFAT.
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Affiliation(s)
- Mary Taub
- Biochemistry Dept., Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, 955 Main Street, Suite 4902, Buffalo, NY 14203, USA.
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11
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Yang L, Xu S, Guo X, Uchida S, Weinstein AM, Wang T, Palmer LG. Regulation of renal Na transporters in response to dietary K. Am J Physiol Renal Physiol 2018; 315:F1032-F1041. [PMID: 29923764 DOI: 10.1152/ajprenal.00117.2018] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Changes in the expression of Na transport proteins were measured in the kidneys of mice with increased dietary K intake for 1 wk. The epithelial Na channel (ENaC) was upregulated, with enhanced expression of full-length and cleaved forms of α-ENaC and cleaved γ-ENaC. At the same time, the amount of the NaCl cotransporter NCC and its phosphorylated form decreased by ~50% and ~80%, respectively. The expression of the phosphorylated form of the Na-K-2Cl cotransporter NKCC2 also decreased, despite an increase in overall protein content. The effect was stronger in males (80%) than in females (40%). This implies that less Na+ is reabsorbed in the thick ascending limb of Henle's loop and distal convoluted tubule along with Cl-, whereas more is reabsorbed in the aldosterone-sensitive distal nephron in exchange for secreted K+. The abundance of the proximal tubule Na/H exchanger NHE3 decreased by ~40%, with similar effects in males and females. Time-course studies indicated that NCC and NHE3 proteins decreased progressively over 7 days on a high-K diet. Expression of mRNA encoding these proteins increased, implying that the decreased protein levels resulted from decreased rates of synthesis or increased rates of degradation. The potential importance of changes in NHE3, NKCC2, and NCC in promoting K+ excretion was assessed with a mathematical model. Simulations indicated that decreased NHE3 produced the largest effect. Regulation of proximal tubule Na+ transport may play a significant role in achieving K homeostasis.
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Affiliation(s)
- Lei Yang
- Department of Physiology and Biophysics, Weill Medical College of Cornell University , New York, New York
| | - Shuhua Xu
- Department of Cellular and Molecular Physiology, Yale University , New Haven, Connecticut
| | - Xiaoyun Guo
- Department of Cellular and Molecular Physiology, Yale University , New Haven, Connecticut
| | - Shinichi Uchida
- Department of Nephrology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan
| | - Alan M Weinstein
- Department of Physiology and Biophysics, Weill Medical College of Cornell University , New York, New York
| | - Tong Wang
- Department of Cellular and Molecular Physiology, Yale University , New Haven, Connecticut
| | - Lawrence G Palmer
- Department of Physiology and Biophysics, Weill Medical College of Cornell University , New York, New York
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Sircana A, De Michieli F, Parente R, Framarin L, Leone N, Berrutti M, Paschetta E, Bongiovanni D, Musso G. Gut microbiota, hypertension and chronic kidney disease: Recent advances. Pharmacol Res 2018; 144:390-408. [PMID: 29378252 DOI: 10.1016/j.phrs.2018.01.013] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Revised: 12/29/2017] [Accepted: 01/22/2018] [Indexed: 02/07/2023]
Abstract
A large number of different microbial species populates intestine. Extensive research has studied the entire microbial population and their genes (microbiome) by using metagenomics, metatranscriptomics and metabolomic analysis. Studies suggest that the imbalances of the microbial community causes alterations in the intestinal homeostasis, leading to repercussions on other systems: metabolic, nervous, cardiovascular, immune. These studies have also shown that alterations in the structure and function of the gut microbiota play a key role in the pathogenesis and complications of Hypertension (HTN) and Chronic Kidney Disease (CKD). Increased blood pressure (BP) and CKD are two leading risk factors for cardiovascular disease and their treatment represents a challenge for the clinicians. In this Review, we discuss mechanisms whereby gut microbiota (GM) and its metabolites act on downstream cellular targets to contribute to the pathogenesis of HTN and CKD, and potential therapeutic implications.
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Affiliation(s)
- Antonio Sircana
- Unità Operativa di Cardiologia, Azienda Ospedaliero Universitaria, Sassari, Italy; Department of Medical Sciences, San Giovanni Battista Hospital, Turin, Italy
| | - Franco De Michieli
- HUMANITAS Gradenigo, University of Turin, Turin, Italy; Department of Medical Sciences, San Giovanni Battista Hospital, Turin, Italy
| | - Renato Parente
- HUMANITAS Gradenigo, University of Turin, Turin, Italy; Department of Medical Sciences, San Giovanni Battista Hospital, Turin, Italy
| | - Luciana Framarin
- HUMANITAS Gradenigo, University of Turin, Turin, Italy; Department of Medical Sciences, San Giovanni Battista Hospital, Turin, Italy
| | - Nicola Leone
- HUMANITAS Gradenigo, University of Turin, Turin, Italy; Department of Medical Sciences, San Giovanni Battista Hospital, Turin, Italy
| | - Mara Berrutti
- HUMANITAS Gradenigo, University of Turin, Turin, Italy; Department of Medical Sciences, San Giovanni Battista Hospital, Turin, Italy
| | - Elena Paschetta
- HUMANITAS Gradenigo, University of Turin, Turin, Italy; Department of Medical Sciences, San Giovanni Battista Hospital, Turin, Italy
| | - Daria Bongiovanni
- HUMANITAS Gradenigo, University of Turin, Turin, Italy; Department of Medical Sciences, San Giovanni Battista Hospital, Turin, Italy
| | - Giovanni Musso
- HUMANITAS Gradenigo, University of Turin, Turin, Italy; Department of Medical Sciences, San Giovanni Battista Hospital, Turin, Italy.
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Hu MC, Bobulescu IA, Quiñones H, Gisler SM, Moe OW. Dopamine reduces cell surface Na +/H + exchanger-3 protein by decreasing NHE3 exocytosis and cell membrane recycling. Am J Physiol Renal Physiol 2017; 313:F1018-F1025. [PMID: 28768665 DOI: 10.1152/ajprenal.00251.2017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Revised: 07/14/2017] [Accepted: 07/24/2017] [Indexed: 01/06/2023] Open
Abstract
The intrarenal autocrine-paracrine dopamine (DA) system mediates a significant fraction of the natriuresis in response to a salt load. DA inhibits a number of Na+ transporters to effect sodium excretion, including the proximal tubule Na+/H+ exchanger-3 (NHE3). DA represent a single hormone that regulates NHE3 at multiple levels, including translation, degradation, endocytosis, and protein phosphorylation. Because cell surface NHE3 protein is determined by the balance between exocytotic insertion and endocytotic retrieval, we examined whether DA acutely affects the rate of NHE3 exocytosis in a cell culture model. DA inhibited NHE3 exocytosis at a dose-dependent manner with a half maximal around 10-6 M. The DA effect on NHE3 exocytosis was blocked by inhibition of protein kinase A and by brefeldin A, which inhibits endoplasmic reticulum-to-Golgi transport. NHE3 directly interacts with the ε-subunit of coatomer protein based on yeast-two-hybrid and coimmunoprecipitation. Because NHE3 has been shown to be recycled back to the cell membrane after endocytosis, we measured NHE3 recycling using a biochemical reinsertion assay and showed that reinsertion of NHE3 back to the membrane is also inhibited by DA. In conclusion, among the many mechanisms by which DA reduces apical membrane NHE3 and induces proximal tubule natriuresis, one additional mechanism is inhibition of exocytotic insertion and reinsertion of NHE3 in the apical cell surface.
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Affiliation(s)
- Ming Chang Hu
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas; .,Charles and Jane Pak Center of Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas
| | - I Alexandru Bobulescu
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas.,Charles and Jane Pak Center of Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Henry Quiñones
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Serge M Gisler
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Orson W Moe
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas.,Department of Physiology, University of Texas Southwestern Medical Center, Dallas, Texas; and.,Charles and Jane Pak Center of Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas
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14
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Abstract
PURPOSE OF REVIEW Hypertension, which is present in about one quarter of the world's population, is responsible for about 41% of the number one cause of death - cardiovascular disease. Not included in these statistics is the effect of sodium intake on blood pressure, even though an increase or a marked decrease in sodium intake can increase blood pressure. This review deals with the interaction of gut microbiota and the kidney with genetics and epigenetics in the regulation of blood pressure and salt sensitivity. RECENT FINDINGS The abundance of the gut microbes, Firmicutes and Bacteroidetes, is associated with increased blood pressure in several models of hypertension, including the spontaneously hypertensive and Dahl salt-sensitive rats. Decreasing gut microbiota by antibiotics can increase or decrease blood pressure that is influenced by genotype. The biological function of probiotics may also be a consequence of epigenetic modification, related, in part, to microRNA. Products of the fermentation of nutrients by gut microbiota can influence blood pressure by regulating expenditure of energy, intestinal metabolism of catecholamines, and gastrointestinal and renal ion transport, and thus, salt sensitivity. SUMMARY The beneficial or deleterious effect of gut microbiota on blood pressure is a consequence of several variables, including genetics, epigenetics, lifestyle, and intake of antibiotics. These variables may influence the ultimate level of blood pressure and control of hypertension.
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Hatanaka M, Kaimori JY, Yamamoto S, Matsui I, Hamano T, Takabatake Y, Ecelbarger CM, Takahara S, Isaka Y, Rakugi H. Azilsartan Improves Salt Sensitivity by Modulating the Proximal Tubular Na+-H+ Exchanger-3 in Mice. PLoS One 2016; 11:e0147786. [PMID: 26807585 PMCID: PMC4725961 DOI: 10.1371/journal.pone.0147786] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Accepted: 01/10/2016] [Indexed: 12/27/2022] Open
Abstract
A potent angiotensin II type-1 receptor blocker, azilsartan, has been reported to reduce blood pressure more effectively than candesartan. Interestingly, azilsartan can also restore the circadian rhythm of blood pressure. We hypothesized that azilsartan could also improve salt sensitivity; thus, we examined the effect of azilsartan on sodium handling in renal tubules. Subtotal nephrectomized C57BL/6 mice received azilsartan (1.0 mg/kg/day), candesartan (0.3 mg/kg/day), or vehicle via the oral route in conjunction with a normal- (0.3%) or high-salt (8.0%) diet. Two weeks later, the azilsartan group showed significantly lower blood pressure during the light period than the candesartan and vehicle groups (azilsartan: 103.1 ± 1.0; candesartan: 111.7 ± 2.7; vehicle: 125.5 ± 2.5 mmHg; P < 0.05; azilsartan or candesartan vs. vehicle). The azilsartan group also showed higher urinary fractional excretion of sodium during the dark period than the candesartan and vehicle groups (azilsartan: 21.37 ± 3.69%; candesartan: 14.17 ± 1.42%; vehicle: 13.85 ± 5.30%; P < 0.05 azilsartan vs. candesartan or vehicle). A pressure—natriuresis curve demonstrated that azilsartan treatment restored salt sensitivity. Immunofluorescence and western blotting showed lower levels of Na+-H+ exchanger-3 (NHE3) protein (the major sodium transporter in renal proximal tubules) in the azilsartan group, but not in the candesartan or vehicle groups. However, azilsartan did not affect NHE3 transcription levels. Interestingly, we did not observe increased expression of downstream sodium transporters, which would have compensated for the increased flow of sodium and water due to non-absorption by NHE3. We also confirmed the mechanism stated above using cultured opossum kidney proximal tubular cells. Results revealed that a proteasomal inhibitor (but not a lysosomal inhibitor) blocked the azilsartan-induced decrease in NHE3 protein expression, suggesting that azilsartan increases NHE3 ubiquitination. In conclusion, azilsartan (but not candesartan) improved salt sensitivity possibly by decreasing NHE3 expression via ubiquitin—proteasomal degradation.
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Affiliation(s)
- Masaki Hatanaka
- Department of Geriatric Medicine and Nephrology, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Jun-Ya Kaimori
- Department of Geriatric Medicine and Nephrology, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
- Department of Advanced Technology for Transplantation, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
- * E-mail:
| | - Satoko Yamamoto
- Department of Geriatric Medicine and Nephrology, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Isao Matsui
- Department of Geriatric Medicine and Nephrology, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Takayuki Hamano
- Department of Geriatric Medicine and Nephrology, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
- Department of Comprehensive Kidney Disease Research, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Yoshitsugu Takabatake
- Department of Geriatric Medicine and Nephrology, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Carolyn M. Ecelbarger
- Department of Medicine, Division of Endocrinology and Metabolism, Georgetown University, Washington D.C., United States of America
| | - Shiro Takahara
- Department of Advanced Technology for Transplantation, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Yoshitaka Isaka
- Department of Geriatric Medicine and Nephrology, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Hiromi Rakugi
- Department of Geriatric Medicine and Nephrology, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
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16
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Soares-da-Silva P, Cabral JM, Magalhães D, Fraga S, Magro F. Amine neurotransmitters, inflammation and epithelial sodium transport. Exp Physiol 2015; 101:459-64. [PMID: 26548358 DOI: 10.1113/ep085284] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Accepted: 11/02/2015] [Indexed: 12/13/2022]
Abstract
NEW FINDINGS What is the topic of this review? The present work reviews the roles of renal and intestinal dopamine and 5-HT in the maintenance of fluid and electrolyte homeostasis. The role of inflammatory agents at the intestinal level that affect fluid and electrolyte homeostasis is also addressed. What advances does it highlight? General mechanisms of epithelial cell ion transport in the gastrointestinal tract and kidney share considerable similarities, particularly with regard to basolateral Na(+) ,K(+-) ATPase as a driving force for the movement of numerous substrates across the cell membrane. The physiological importance of the renal actions of monoamines (dopamine, noradrenaline and 5-HT) mainly depends on the sources of the amines in the kidney and on their availability to activate the amine-specific receptors. Dopamine and 5-HT are also relatively abundant in the mucosal cell layer of the intestine, and recent evidence suggests their physiological relevance in regulating electrolyte transport. The gastrointestinal tract can be an important site for the loss of water and electrolytes, in the presence of intestinal inflammation. General mechanisms of epithelial cell ion transport in the gastrointestinal tract and kidney share considerable similarities with regard to basolateral Na(+) ,K(+) -ATPase as a driving force for the movement of numerous substrates across the cell membrane. The present work reviews the roles of renal and intestinal dopamine and 5-HT in the maintenance of fluid and electrolyte homeostasis. The role of inflammatory agents at the intestinal level that affect fluid and electrolyte homeostasis is also addressed.
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Affiliation(s)
- Patrício Soares-da-Silva
- Department of Pharmacology and Therapeutics, Faculty of Medicine, University of Porto, Porto, Portugal.,MedInUP - Center for Drug Discovery and Innovative Medicines, University of Porto, Porto, Portugal
| | - José Miguel Cabral
- Department of Pharmacology and Therapeutics, Faculty of Medicine, University of Porto, Porto, Portugal
| | - Diogo Magalhães
- Department of Pharmacology and Therapeutics, Faculty of Medicine, University of Porto, Porto, Portugal
| | - Sónia Fraga
- Department of Pharmacology and Therapeutics, Faculty of Medicine, University of Porto, Porto, Portugal.,MedInUP - Center for Drug Discovery and Innovative Medicines, University of Porto, Porto, Portugal
| | - Fernando Magro
- Department of Pharmacology and Therapeutics, Faculty of Medicine, University of Porto, Porto, Portugal.,MedInUP - Center for Drug Discovery and Innovative Medicines, University of Porto, Porto, Portugal
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Abstract
PURPOSE OF REVIEW This review will highlight recent findings concerning the regulation and signalling of the intrarenal dopaminergic system and the emerging evidence for its importance in blood pressure regulation. RECENT FINDINGS There is an increasing evidence that the intrarenal dopaminergic system plays an important role in the regulation of blood pressure, and defects in dopamine signalling appear to be involved in the development of hypertension. Recent experimental models have definitively demonstrated that abnormalities in intrarenal dopamine production or receptor signalling can predispose to salt-sensitive hypertension and a dysregulated renin-angiotensin system. There are also new results indicating the importance of dopamine receptor mediated regulation of salt and water homeostasis along the nephron, and new studies indicating the role that the intrarenal dopaminergic system plays to mitigate the production of reactive oxygen species and progression of chronic renal disease. SUMMARY New studies underscore the importance of the intrarenal dopaminergic system in the regulation of renal function and indicate how alterations in dopamine production or signalling may underlie the development of hypertension and kidney injury.
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Li Y, Wang N, Chen C, He D, Yang J, Zeng C. Inhibitory effect of D3dopamine receptor on migration of vascular smooth muscle cells induced by synergistic effect of angiotensin II and aldosterone. Clin Exp Hypertens 2014; 37:288-93. [DOI: 10.3109/10641963.2014.960971] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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Isaksson GL, Stubbe J, Lyngs Hansen P, Jensen BL, Bie P. Salt sensitivity of renin secretion, glomerular filtration rate and blood pressure in conscious Sprague-Dawley rats. Acta Physiol (Oxf) 2014; 210:446-54. [PMID: 24188244 DOI: 10.1111/apha.12191] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Revised: 10/15/2013] [Accepted: 10/30/2013] [Indexed: 12/20/2022]
Abstract
AIM We hypothesized that in normal rats in metabolic steady state, (i) the plasma renin concentration (PRC) is log-linearly related to Na(+) intake (NaI), (ii) the concurrent changes in mean arterial pressure (MABP) and glomerular filtration rate (GFR) are negligible and (iii) the function PRC = f(NaI) is altered by β₁-adrenoceptor blockade (metoprolol) and surgical renal denervation (DNX). METHODS In catheterized, conscious rats on low-Na(+) diet (0.004% Na(+)), NaI was increased by up to 120-fold, in four 3-day steps, by intravenous saline infusion. MABP was recorded continuously, PRC measured in arterial blood, and GFR estimated by inulin clearance. RESULTS Steady states were achieved within 3 days. PRC [mIU L(-1)] was log-linearly related to NaI [mmol kg(-1) day(-1)]: PRC = -9.9 log (NaI) + 22. Set point (22 mIU L(-1) at NaI = 1) and slope (9.9 mIU per decade NaI) were independent of metoprolol administration and DNX. MABP and GFR were markedly salt-sensitive: MABP [mmHg] = 4.9 log (NaI) + 99 (P < 0.01), and GFR [mL min(-1)] = 1.4 log (NaI) + 8.3 (P < 0.01). MABP increased similarly (approx. 10%, P < 0.001) irrespective of pre-treatment. Metoprolol, but not DNX, reduced MABP, HR, and GFR (all P < 0.01). Salt sensitivity of GFR was not observed in DNX rats. CONCLUSION Log-linear relations to sodium intake exist not only for PRC, but also for MABP and GFR, which per 10-fold increase in sodium intake rose by 5 mmHg and 1.4 mL min(-1) respectively. Steady-state levels of PRC appear independent of renal nerves. MABP and GFR seem markedly salt sensitive in normal rats.
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Affiliation(s)
- G. L. Isaksson
- Department of Cardiovascular and Renal Research; Institute of Molecular Medicine; University of Southern Denmark; Odense Denmark
| | - J. Stubbe
- Department of Cardiovascular and Renal Research; Institute of Molecular Medicine; University of Southern Denmark; Odense Denmark
| | - P. Lyngs Hansen
- Department of Physics, Chemistry and Pharmacy; University of Southern Denmark; Odense Denmark
| | - B. L. Jensen
- Department of Cardiovascular and Renal Research; Institute of Molecular Medicine; University of Southern Denmark; Odense Denmark
| | - P. Bie
- Department of Cardiovascular and Renal Research; Institute of Molecular Medicine; University of Southern Denmark; Odense Denmark
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Fuster DG, Alexander RT. Traditional and emerging roles for the SLC9 Na+/H+ exchangers. Pflugers Arch 2013; 466:61-76. [PMID: 24337822 DOI: 10.1007/s00424-013-1408-8] [Citation(s) in RCA: 115] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Revised: 11/14/2013] [Accepted: 11/20/2013] [Indexed: 10/25/2022]
Abstract
The SLC9 gene family encodes Na(+)/H(+) exchangers (NHEs). These transmembrane proteins transport ions across lipid bilayers in a diverse array of species from prokaryotes to eukaryotes, including plants, fungi, and animals. They utilize the electrochemical gradient of one ion to transport another ion against its electrochemical gradient. Currently, 13 evolutionarily conserved NHE isoforms are known in mammals [22, 46, 128]. The SLC9 gene family (solute carrier classification of transporters: www.bioparadigms.org) is divided into three subgroups [46]. The SLC9A subgroup encompasses plasmalemmal isoforms NHE1-5 (SLC9A1-5) and the predominantly intracellular isoforms NHE6-9 (SLC9A6-9). The SLC9B subgroup consists of two recently cloned isoforms, NHA1 and NHA2 (SLC9B1 and SLC9B2, respectively). The SLC9C subgroup consist of a sperm specific plasmalemmal NHE (SLC9C1) and a putative NHE, SLC9C2, for which there is currently no functional data [46]. NHEs participate in the regulation of cytosolic and organellar pH as well as cell volume. In the intestine and kidney, NHEs are critical for transepithelial movement of Na(+) and HCO3(-) and thus for whole body volume and acid-base homeostasis [46]. Mutations in the NHE6 or NHE9 genes cause neurological disease in humans and are currently the only NHEs directly linked to human disease. However, it is becoming increasingly apparent that members of this gene family contribute to the pathophysiology of multiple human diseases.
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Affiliation(s)
- Daniel G Fuster
- Division of Nephrology, Hypertension and Clinical Pharmacology and Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland,
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Armando I, Villar VAM, Jones JE, Lee H, Wang X, Asico LD, Yu P, Yang J, Escano CS, Pascua-Crusan AM, Felder RA, Jose PA. Dopamine D3 receptor inhibits the ubiquitin-specific peptidase 48 to promote NHE3 degradation. FASEB J 2013; 28:1422-34. [PMID: 24308971 DOI: 10.1096/fj.13-243840] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The dopamine D3 receptor (D3R) is crucial in the regulation of blood pressure and sodium balance, in that Drd3 gene ablation in mice results in hypertension and failure to excrete a dietary salt load. The mechanism responsible for the renal sodium retention in these mice is largely unknown. We now offer and describe a novel mechanism by which D3R decreases sodium transport in the long term by inhibiting the deubiquitinylating activity of ubiquitin-specific peptidase 48 (USP48), thereby promoting Na(+)-H(+) exchanger (NHE)-3 degradation. We found that stimulation with the D3R-specific agonist PD128907 (1 μM, 30 min) promoted the interaction and colocalization among D3R, NHE3, and USP48; inhibited USP48 activity (-35±6%, vs. vehicle), resulting in increased ubiquitinylated NHE3 (+140±10%); and decreased NHE3 expression (-50±9%) in human renal proximal tubule cells (hRPTCs). USP48 silencing decreased NHE3's half-life (USP48 siRNA t1/2=6.1 h vs. vehicle t1/2=12.9 h), whereas overexpression of USP48 increased NHE3 half-life (t1/2=21.8 h), indicating that USP48 protects NHE3 from degradation via deubiquitinylation. USP48 accounted for ∼30% of the total deubiquitinylating activity in these cells. Extending our studies in vivo, we found that pharmacologic blockade of D3R via the D3R-specific antagonist GR103691 (1 μg/kg/min, 4 d) in C57Bl/6J mice increased renal NHE3 expression (+310±15%, vs. vehicle), whereas an innovative kidney-restricted Usp48 silencing via siRNA (3 μg/d, 7 d) increased ubiquitinylated NHE3 (+250±30%, vs. controls), decreased total NHE3 (-23±2%), and lowered blood pressure (-24±2 mm Hg), compared with that in control mice that received either the vehicle or nonsilencing siRNA. Our data demonstrate a crucial role for the dynamic interaction between D3R and USP48 in the regulation of NHE3 expression and function.
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Affiliation(s)
- Ines Armando
- 2Division of Nephrology, Department of Medicine, University of Maryland School of Medicine, 20 Penn St., HSF II, Ste. S003C, Baltimore, MD, USA 21201,
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