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Tsikas D. Acetazolamide and human carbonic anhydrases: retrospect, review and discussion of an intimate relationship. J Enzyme Inhib Med Chem 2024; 39:2291336. [PMID: 38078375 DOI: 10.1080/14756366.2023.2291336] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Accepted: 11/30/2023] [Indexed: 12/18/2023] Open
Abstract
Acetazolamide (AZM) is a strong pharmacological sulphonamide-type (R-SO2-NH2, pKa 7.2) inhibitor of the activity of several carbonic anhydrase (CA) isoforms, notably of renal CA II (Ki, 12 nM) and CA IV (Ki, 74 nM). AZM is clinically used for about eighty years in various diseases including epilepsy and glaucoma. Pharmacological AZM increases temporarily the urinary excretion of bicarbonate (HCO3-) and sodium ions (Na+) and sustainably the urinary pH. AZM is excreted almost unchanged over several hours at high rates in the urine. Closely parallel concentrations of circulating and excretory AZM are observed upon administration of therapeutical doses of AZM. In a proof-of-principle study, we investigated the effects of the ingestion of a 250-mg AZM-containing tablet by a healthy volunteer on the urinary excretion of organic and inorganic substances over 5 h (range, 0, 0.5, 1, 1.5, 2, 3, 4, 5 h). Measured analytes included: AZM, amino acids and their metabolites such as guanidinoacetate, i.e. the precursor of creatine, of asymmetrically (ADMA) and symmetrically (SDMA) dimethylated arginine, nitrite (O = N-O-, pKa 3.4) and nitrate (O2N-O-, pKa -1.37), the major metabolites of nitric oxide (NO), the C-H acidic malondialdehyde (MDA; (CHO)2CH2, pKa 4.5), and creatinine for correction of analytes excretion. All analytes were measured by validated isotopologues using gas chromatography-mass spectrometry (GC-MS) methods. AZM excretion in the urine reached its maximum value after 2 h and was fairly stable for the next 3 h. Time series analysis by the ARIMA method was performed. AZM ingestion increased temporarily the urinary excretion of the amino acids Leu + Ile, nitrite and nitrate, decreased temporarily the urinary excretion of other amino acids. AZM decreased sustainably the urinary excretion of MDA, a biomarker of oxidative stress (i.e. lipid peroxidation). Whether this decrease is due to inhibition of the excretion of MDA or attenuation of oxidative stress by AZM is unknown. The acute and chronic effects of AZM on the urinary excretion of electrolytes and physiological substances reported in the literature are discussed in depth in the light of its extraordinary pharmacokinetics and pharmacodynamics. Tolerance development/drug resistance to AZM in chronic use and potential mechanisms are also addressed.
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Affiliation(s)
- Dimitrios Tsikas
- Core Unit Proteomics, Institute of Toxicology, Hannover Medical School, Hannover, Germany
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2
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Gantsova E, Serova O, Vishnyakova P, Deyev I, Elchaninov A, Fatkhudinov T. Mechanisms and physiological relevance of acid-base exchange in functional units of the kidney. PeerJ 2024; 12:e17316. [PMID: 38699185 PMCID: PMC11064853 DOI: 10.7717/peerj.17316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Accepted: 04/09/2024] [Indexed: 05/05/2024] Open
Abstract
This review discusses the importance of homeostasis with a particular emphasis on the acid-base (AB) balance, a crucial aspect of pH regulation in living systems. Two primary organ systems correct deviations from the standard pH balance: the respiratory system via gas exchange and the kidneys via proton/bicarbonate secretion and reabsorption. Focusing on kidney functions, we describe the complexity of renal architecture and its challenges for experimental research. We address specific roles of different nephron segments (the proximal convoluted tubule, the loop of Henle and the distal convoluted tubule) in pH homeostasis, while explaining the physiological significance of ion exchange processes maintained by the kidneys, particularly the role of bicarbonate ions (HCO3-) as an essential buffer system of the body. The review will be of interest to researchers in the fields of physiology, biochemistry and molecular biology, which builds a strong foundation and critically evaluates existing studies. Our review helps identify the gaps of knowledge by thoroughly understanding the existing literature related to kidney acid-base homeostasis.
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Affiliation(s)
- Elena Gantsova
- Avtsyn Research Institute of Human Morphology of Federal State Budgetary Scientific Institution “Petrovsky National Research Centre of Surgery”, Moscow, Russia
- Research Institute of Molecular and Cellular Medicine, Peoples’ Friendship University of Russia (RUDN University), Moscow, Russia
| | - Oxana Serova
- Shemyakin–Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russian Federation
| | - Polina Vishnyakova
- Research Institute of Molecular and Cellular Medicine, Peoples’ Friendship University of Russia (RUDN University), Moscow, Russia
- National Medical Research Center for Obstetrics, Gynecology and Perinatology Named after Academician V.I. Kulakov of Ministry of Healthcare of Russian Federation, Moscow, Russian Federation
| | - Igor Deyev
- Shemyakin–Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russian Federation
| | - Andrey Elchaninov
- Avtsyn Research Institute of Human Morphology of Federal State Budgetary Scientific Institution “Petrovsky National Research Centre of Surgery”, Moscow, Russia
- Research Institute of Molecular and Cellular Medicine, Peoples’ Friendship University of Russia (RUDN University), Moscow, Russia
| | - Timur Fatkhudinov
- Avtsyn Research Institute of Human Morphology of Federal State Budgetary Scientific Institution “Petrovsky National Research Centre of Surgery”, Moscow, Russia
- Research Institute of Molecular and Cellular Medicine, Peoples’ Friendship University of Russia (RUDN University), Moscow, Russia
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3
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Vitzthum H, Meyer-Schwesinger C, Ehmke H. Novel functions of the anion exchanger AE4 (SLC4A9). Pflugers Arch 2024; 476:555-564. [PMID: 38195948 PMCID: PMC11006790 DOI: 10.1007/s00424-023-02899-5] [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: 10/09/2023] [Revised: 12/12/2023] [Accepted: 12/14/2023] [Indexed: 01/11/2024]
Abstract
The kidney plays a crucial role in acid-base homeostasis. In the distal nephron, α-intercalated cells contribute to urinary acid (H+) secretion and β-intercalated cells accomplish urinary base (HCO3-) secretion. β-intercalated cells regulate the acid base status through modulation of the apical Cl-/HCO3- exchanger pendrin (SLC26A4) activity. In this review, we summarize and discuss our current knowledge of the physiological role of the renal transporter AE4 (SLC4A9). The AE4, as cation-dependent Cl-/HCO3- exchanger, is exclusively expressed in the basolateral membrane of β-intercalated cells and is essential for the sensing of metabolic acid-base disturbances in mice, but not for renal sodium reabsorption and plasma volume control. Potential intracellular signaling pathways are discussed that might link basolateral acid-base sensing through the AE4 to apical pendrin activity.
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Affiliation(s)
- Helga Vitzthum
- Institute of Cellular and Integrative Physiology, Center for Experimental Medicine, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246, Hamburg, Germany.
| | - Catherine Meyer-Schwesinger
- Institute of Cellular and Integrative Physiology, Center for Experimental Medicine, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246, Hamburg, Germany
| | - Heimo Ehmke
- Institute of Cellular and Integrative Physiology, Center for Experimental Medicine, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246, Hamburg, Germany
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4
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Song T, Broadbent C, Kuang R. GNTD: reconstructing spatial transcriptomes with graph-guided neural tensor decomposition informed by spatial and functional relations. Nat Commun 2023; 14:8276. [PMID: 38092776 PMCID: PMC10719260 DOI: 10.1038/s41467-023-44017-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2023] [Accepted: 11/15/2023] [Indexed: 12/17/2023] Open
Abstract
Spatially-resolved RNA profiling has now been widely used to understand cells' structural organizations and functional roles in tissues, yet it is challenging to reconstruct the whole spatial transcriptomes due to various inherent technical limitations in tissue section preparation and RNA capture and fixation in the application of the spatial RNA profiling technologies. Here, we introduce a graph-guided neural tensor decomposition (GNTD) model for reconstructing whole spatial transcriptomes in tissues. GNTD employs a hierarchical tensor structure and formulation to explicitly model the high-order spatial gene expression data with a hierarchical nonlinear decomposition in a three-layer neural network, enhanced by spatial relations among the capture spots and gene functional relations for accurate reconstruction from highly sparse spatial profiling data. Extensive experiments on 22 Visium spatial transcriptomics datasets and 3 high-resolution Stereo-seq datasets as well as simulation data demonstrate that GNTD consistently improves the imputation accuracy in cross-validations driven by nonlinear tensor decomposition and incorporation of spatial and functional information, and confirm that the imputed spatial transcriptomes provide a more complete gene expression landscape for downstream analyses of cell/spot clustering for tissue segmentation, and spatial gene expression clustering and visualizations.
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Affiliation(s)
- Tianci Song
- Department of Computer Science and Engineering, University of Minnesota Twin Cities, Minneapolis, 55414, MN, USA
| | - Charles Broadbent
- Department of Computer Science and Engineering, University of Minnesota Twin Cities, Minneapolis, 55414, MN, USA
| | - Rui Kuang
- Department of Computer Science and Engineering, University of Minnesota Twin Cities, Minneapolis, 55414, MN, USA.
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5
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Gantsova EA, Serova OV, Eladari D, Bobrovskiy DM, Petrenko AG, Elchaninov AV, Deyev IE. A Comparative Kidney Transcriptome Analysis of Bicarbonate-Loaded insrr-Null Mice. Curr Issues Mol Biol 2023; 45:9709-9722. [PMID: 38132452 PMCID: PMC10742211 DOI: 10.3390/cimb45120606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Revised: 11/23/2023] [Accepted: 11/28/2023] [Indexed: 12/23/2023] Open
Abstract
The maintenance of plasma pH is critical for life in all organisms. The kidney plays a critical role in acid-base regulation in vertebrates by controlling the plasma concentration of bicarbonate. The receptor tyrosine kinase IRR (insulin receptor-related receptor) is expressed in renal β-intercalated cells and is involved in alkali sensing due to its ability to autophosphorylate under alkalization of extracellular medium (pH > 7.9). In mice with a knockout of the insrr gene, which encodes for IRR, urinary bicarbonate secretion in response to alkali loading is impaired. The specific regulatory mechanisms in the kidney that are under the control of IRR remain unknown. To address this issue, we analyzed and compared the kidney transcriptomes of wild-type and insrr knockout mice under basal or bicarbonate-loaded conditions. Transcriptomic analyses revealed a differential regulation of a number of genes in the kidney. Using TaqMan real-time PCR, we confirmed different expressions of the slc26a4, rps7, slc5a2, aqp6, plcd1, gapdh, rny3, kcnk5, slc6a6 and atp6v1g3 genes in IRR knockout mice. Also, we found that the expression of the kcnk5 gene is increased in wild-type mice after bicarbonate loading but not in knockout mice. Gene set enrichment analysis between the IRR knockout and wild-type samples identified that insrr knockout causes alterations in expression of genes related mostly to the ATP metabolic and electron transport chain processes.
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Affiliation(s)
- E. A. Gantsova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the RAS, Moscow 117997, Russia; (E.A.G.); (O.V.S.); (A.G.P.)
- Avtsyn Research Institute of Human Morphology of Federal State Budgetary Scientific Institution “Petrovsky National Research Centre of Surgery”, Moscow 117418, Russia;
| | - O. V. Serova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the RAS, Moscow 117997, Russia; (E.A.G.); (O.V.S.); (A.G.P.)
| | - D. Eladari
- Service de Médecine de Précision des Maladies Métaboliques et Rénales, CHU Amiens-Picardie, Université de Picardie Jules Verne, 80054 Amiens, France
| | - D. M. Bobrovskiy
- School of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - A. G. Petrenko
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the RAS, Moscow 117997, Russia; (E.A.G.); (O.V.S.); (A.G.P.)
| | - A. V. Elchaninov
- Avtsyn Research Institute of Human Morphology of Federal State Budgetary Scientific Institution “Petrovsky National Research Centre of Surgery”, Moscow 117418, Russia;
| | - I. E. Deyev
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the RAS, Moscow 117997, Russia; (E.A.G.); (O.V.S.); (A.G.P.)
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6
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Hajjar S, Zhou X. pH sensing at the intersection of tissue homeostasis and inflammation. Trends Immunol 2023; 44:807-825. [PMID: 37714775 PMCID: PMC10543622 DOI: 10.1016/j.it.2023.08.008] [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: 08/08/2023] [Revised: 08/13/2023] [Accepted: 08/13/2023] [Indexed: 09/17/2023]
Abstract
pH is tightly maintained at cellular, tissue, and systemic levels, and altered pH - particularly in the acidic range - is associated with infection, injury, solid tumors, and physiological and pathological inflammation. However, how pH is sensed and regulated and how it influences immune responses remain poorly understood at the tissue level. Applying conceptual frameworks of homeostatic and inflammatory circuitries, we categorize cellular and tissue components engaged in pH regulation, drawing parallels from established cases in physiology. By expressing various intracellular (pHi) and extracellular pH (pHe)-sensing receptors, the immune system may integrate information on tissue and cellular states into the regulation of homeostatic and inflammatory programs. We introduce the novel concept of resistance and adaptation responses to rationalize pH-dependent immunomodulation intertwined with homeostatic equilibrium and inflammatory control. We discuss emerging challenges and opportunities in understanding the immunological roles of pH sensing, which might reveal new strategies to combat inflammation and restore tissue homeostasis.
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Affiliation(s)
- Stephanie Hajjar
- Division of Gastroenterology, Hepatology and Nutrition, Boston Children's Hospital, Boston, MA 02115, USA; Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA; Broad Institute of MIT and Harvard, 300 Longwood Ave, Boston, MA 02115, USA
| | - Xu Zhou
- Division of Gastroenterology, Hepatology and Nutrition, Boston Children's Hospital, Boston, MA 02115, USA; Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA; Broad Institute of MIT and Harvard, 300 Longwood Ave, Boston, MA 02115, USA.
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7
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Vitzthum H, Koch M, Eckermann L, Svendsen SL, Berg P, Hübner CA, Wagner CA, Leipziger J, Meyer-Schwesinger C, Ehmke H. The AE4 transporter mediates kidney acid-base sensing. Nat Commun 2023; 14:3051. [PMID: 37236964 DOI: 10.1038/s41467-023-38562-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Accepted: 05/05/2023] [Indexed: 05/28/2023] Open
Abstract
The kidney plays a key role in the correction of systemic acid-base imbalances. Central for this regulation are the intercalated cells in the distal nephron, which secrete acid or base into the urine. How these cells sense acid-base disturbances is a long-standing question. Intercalated cells exclusively express the Na+-dependent Cl-/HCO3- exchanger AE4 (Slc4a9). Here we show that AE4-deficient mice exhibit a major dysregulation of acid-base balance. By combining molecular, imaging, biochemical and integrative approaches, we demonstrate that AE4-deficient mice are unable to sense and appropriately correct metabolic alkalosis and acidosis. Mechanistically, a lack of adaptive base secretion via the Cl-/HCO3- exchanger pendrin (Slc26a4) is the key cellular cause of this derailment. Our findings identify AE4 as an essential part of the renal sensing mechanism for changes in acid-base status.
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Affiliation(s)
- H Vitzthum
- Center for Experimental Medicine, Institute of Cellular and Integrative Physiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - M Koch
- Center for Experimental Medicine, Institute of Cellular and Integrative Physiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - L Eckermann
- Center for Experimental Medicine, Institute of Cellular and Integrative Physiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - S L Svendsen
- Department of Biomedicine, Physiology, Health, Aarhus University, Aarhus, Denmark
| | - P Berg
- Department of Biomedicine, Physiology, Health, Aarhus University, Aarhus, Denmark
| | - C A Hübner
- Institute of Human Genetics, University Hospital Jena, Friedrich Schiller University, Jena, Germany
| | - C A Wagner
- Institute of Physiology, University of Zurich, Zurich, Switzerland
- National Center of Competence in Research NCCR Kidney.CH, Zurich, Switzerland
| | - J Leipziger
- Department of Biomedicine, Physiology, Health, Aarhus University, Aarhus, Denmark
| | - C Meyer-Schwesinger
- Center for Experimental Medicine, Institute of Cellular and Integrative Physiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - H Ehmke
- Center for Experimental Medicine, Institute of Cellular and Integrative Physiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
- German Center for Cardiovascular Research, Partner Site Hamburg/Kiel/Lübeck, Hamburg, Germany.
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8
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Ferdaus MZ, Terker AS, Koumangoye R, Wall SM, Delpire E. Bicarbonate is the primary inducer of KCC3a expression in renal cortical B-type intercalated cells. Am J Physiol Cell Physiol 2023; 324:C1171-C1178. [PMID: 37036298 PMCID: PMC10191129 DOI: 10.1152/ajpcell.00094.2023] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Revised: 03/30/2023] [Accepted: 03/30/2023] [Indexed: 04/11/2023]
Abstract
A primary function of intercalated cells in the distal tubule of the kidney is to maintain pH homeostasis. For example, type B intercalated cells secrete bicarbonate largely through the action of the apical Cl-/HCO3- exchanger, pendrin, which helps correct metabolic alkalosis. Since both the K-Cl cotransporter, KCC3a and pendrin colocalize to the apical region of type B and non-A, non-B intercalated cells and since both are upregulated in models of metabolic alkalosis, such as with dietary NaHCO3 loading, we raised the possibility that apical KCC3a facilitates pendrin-mediated bicarbonate secretion, such as through apical Cl- recycling. The purpose of this study was to determine if KCC3a abundance changes through intake of bicarbonate alone or through bicarbonate plus its accompanying cation, and if it requires a direct interaction with pendrin or the renin-angiotensin-aldosterone system. We observed that KCC3a protein abundance, but not mRNA, increases in a mouse model of metabolic alkalosis, achieved with dietary NaHCO3 or KHCO3 intake. Bicarbonate ion increases KCC3a abundance, both in vivo and in vitro, independently of the accompanying cation. Moreover, bicarbonate intake upregulates KCC3a independently of aldosterone or angiotensin II. Since NaHCO3 intake increased KCC3a abundance in wild-type as well as in pendrin knockout mice, this KCC3a upregulation by bicarbonate does not depend on a direct interaction with pendrin. We conclude that increased extracellular bicarbonate, as observed in models of metabolic alkalosis, directly raises KCC3a abundance independently of angiotensin II, aldosterone, or changes in KCC3a transcription and does not involve a direct interaction with pendrin.NEW & NOTEWORTHY KCC3a expression is stimulated in alkalemia. This paper shows that bicarbonate itself is mediating this effect through a posttranscriptional mechanism. The paper also shows that this phenomenon is not mediated by aldosterone or angiotensin II.
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Affiliation(s)
- Mohammed Z Ferdaus
- Department of Anesthesiology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States
| | - Andrew S Terker
- Division of Nephrology, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, United States
| | - Rainelli Koumangoye
- Department of Anesthesiology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States
| | - Susan M Wall
- Division of Nephrology, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, United States
| | - Eric Delpire
- Department of Anesthesiology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States
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9
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Sharma V, Sahu B, Kumar Das U, Kumar Patra G. A reversible fluorescent-colorimetric malononitrile based novel Schiff-base chemosensor for visual detection of bicarbonate ion in aqueous solution. Inorganica Chim Acta 2023. [DOI: 10.1016/j.ica.2023.121491] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/05/2023]
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10
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Kalim KW, Yang JQ, Wunderlich M, Modur V, Nguyen P, Li Y, Wen T, Davis AK, Verma R, Lu QR, Jegga AG, Zheng Y, Guo F. Targeting of Cdc42 GTPase in regulatory T cells unleashes antitumor T-cell immunity. J Immunother Cancer 2022; 10:jitc-2022-004806. [PMID: 36427906 PMCID: PMC9703354 DOI: 10.1136/jitc-2022-004806] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/11/2022] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND Cancer immunotherapy has taken center stage in cancer treatment. However, the current immunotherapies only benefit a small proportion of patients with cancer, necessitating better understanding of the mechanisms of tumor immune evasion and improved cancer immunotherapy strategies. Regulatory T (Treg) cells play an important role in maintaining immune tolerance through inhibiting effector T-cell function. In the tumor microenvironment, Treg cells are used by tumor cells to counteract effector T cell-mediated tumor suppression. Targeting Treg cells may thus unleash the antitumor activity of effector T cells. While systemic depletion of Treg cells can cause excessive effector T-cell responses and subsequent autoimmune diseases, controlled targeting of Treg cells may benefit patients with cancer. METHODS Treg cells from Treg cell-specific heterozygous Cdc42 knockout mice, C57BL/6 mice treated with a Cdc42 inhibitor CASIN, and control mice were examined for their homeostasis and stability by flow cytometry. The autoimmune responses in Treg cell-specific heterozygous Cdc42 knockout mice, CASIN-treated C57BL/6 mice, and control mice were assessed by H&E staining and ELISA. Antitumor T-cell immunity in Treg cell-specific heterozygous Cdc42 knockout mice, CASIN-treated C57BL/6 mice, humanized NSGS mice, and control mice was assessed by challenging the mice with MC38 mouse colon cancer cells, KPC mouse pancreatic cancer cells, or HCT116 human colon cancer cells. RESULTS Treg cell-specific heterozygous deletion or pharmacological targeting of Cdc42 with CASIN does not affect Treg cell numbers but induces Treg cell instability, leading to antitumor T-cell immunity without detectable autoimmune reactions. Cdc42 targeting causes an additive effect on immune checkpoint inhibitor anti-programmed cell death protein-1 antibody-induced T-cell response against mouse and human tumors. Mechanistically, Cdc42 targeting induces Treg cell instability and unleashes antitumor T-cell immunity through carbonic anhydrase I-mediated pH changes. CONCLUSIONS Rational targeting of Cdc42 in Treg cells holds therapeutic promises in cancer immunotherapy.
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Affiliation(s)
- Khalid W Kalim
- Division of Experimental Hematology and Cancer Biology, Children's Hospital Medical Center, and Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA
| | - Jun-Qi Yang
- Division of Experimental Hematology and Cancer Biology, Children's Hospital Medical Center, and Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA
| | - Mark Wunderlich
- Division of Experimental Hematology and Cancer Biology, Children's Hospital Medical Center, and Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA
| | - Vishnu Modur
- Division of Experimental Hematology and Cancer Biology, Children's Hospital Medical Center, and Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA
| | - Phuong Nguyen
- Division of Experimental Hematology and Cancer Biology, Children's Hospital Medical Center, and Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA
| | - Yuan Li
- Division of Experimental Hematology and Cancer Biology, Children's Hospital Medical Center, and Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA
| | - Ting Wen
- Division of Allergy and Immunology, Children's Hospital Medical Center, and Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA
| | - Ashley Kuenzi Davis
- Division of Experimental Hematology and Cancer Biology, Children's Hospital Medical Center, and Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA
| | - Ravinder Verma
- Division of Experimental Hematology and Cancer Biology, Children's Hospital Medical Center, and Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA
| | - Qing Richard Lu
- Division of Experimental Hematology and Cancer Biology, Children's Hospital Medical Center, and Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA
| | - Anil G Jegga
- Division of Biomedical Informatics, Children's Hospital Medical Center, and Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA
| | - Yi Zheng
- Division of Experimental Hematology and Cancer Biology, Children's Hospital Medical Center, and Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA
| | - Fukun Guo
- Division of Experimental Hematology and Cancer Biology, Children's Hospital Medical Center, and Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA
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11
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Abstract
Extracellular proton concentration is at 40 nM when pH is 7.4. In disease conditions such as brain ischemia, proton concentration can reach µM range. To respond to this increase in extracellular proton concentration, the mammalian brain expresses at least three classes of proton receptors. Acid-sensing ion channels (ASICs) are the main neuronal cationic proton receptor. The proton-activated chloride channel (PAC), which is also known as (aka) acid-sensitive outwardly rectifying anion channel (ASOR; TMEM206), mediates acid-induced chloride currents. Besides proton-activated channels, GPR4, GPR65 (aka TDAG8, T-cell death-associated gene 8), and GPR68 (aka OGR1, ovarian cancer G protein-coupled receptor 1) function as proton-sensitive G protein-coupled receptors (GPCRs). Though earlier studies on these GPCRs mainly focus on peripheral cells, we and others have recently provided evidence for their functional importance in brain injury. Specifically, GPR4 shows strong expression in brain endothelium, GPR65 is present in a fraction of microglia, while GPR68 exhibits predominant expression in brain neurons. Here, to get a better view of brain acid signaling and its contribution to ischemic injury, we will review the recent findings regarding the differential contribution of proton-sensitive GPCRs to cerebrovascular function, neuroinflammation, and neuronal injury following acidosis and brain ischemia.
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Affiliation(s)
- Xiang-ming Zha
- Division of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Missouri-Kansas City, Kansas City, MO, USA
- Xiang-ming Zha, Division of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Missouri-Kansas City, 2464 Charlotte St, Kansas City, MO 64108, USA.
| | - Zhi-Gang Xiong
- Department of Neurobiology, Morehouse School of Medicine, Atlanta, GA, USA
| | - Roger P Simon
- Department of Neurobiology, Morehouse School of Medicine, Atlanta, GA, USA
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12
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Imenez Silva PH, Wagner CA. Physiological relevance of proton-activated GPCRs. Pflugers Arch 2022; 474:487-504. [PMID: 35247105 PMCID: PMC8993716 DOI: 10.1007/s00424-022-02671-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Revised: 02/07/2022] [Accepted: 02/08/2022] [Indexed: 12/12/2022]
Abstract
The detection of H+ concentration variations in the extracellular milieu is accomplished by a series of specialized and non-specialized pH-sensing mechanisms. The proton-activated G protein–coupled receptors (GPCRs) GPR4 (Gpr4), TDAG8 (Gpr65), and OGR1 (Gpr68) form a subfamily of proteins capable of triggering intracellular signaling in response to alterations in extracellular pH around physiological values, i.e., in the range between pH 7.5 and 6.5. Expression of these receptors is widespread for GPR4 and OGR1 with particularly high levels in endothelial cells and vascular smooth muscle cells, respectively, while expression of TDAG8 appears to be more restricted to the immune compartment. These receptors have been linked to several well-studied pH-dependent physiological activities including central control of respiration, renal adaption to changes in acid–base status, secretion of insulin and peripheral responsiveness to insulin, mechanosensation, and cellular chemotaxis. Their role in pathological processes such as the genesis and progression of several inflammatory diseases (asthma, inflammatory bowel disease), and tumor cell metabolism and invasiveness, is increasingly receiving more attention and makes these receptors novel and interesting targets for therapy. In this review, we cover the role of these receptors in physiological processes and will briefly discuss some implications for disease processes.
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Affiliation(s)
- Pedro H Imenez Silva
- Institute of Physiology, University of Zurich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland. .,National Center of Competence in Research NCCR Kidney.CH, Zurich, Switzerland.
| | - Carsten A Wagner
- Institute of Physiology, University of Zurich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland. .,National Center of Competence in Research NCCR Kidney.CH, Zurich, Switzerland.
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13
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Song T, Markham KK, Li Z, Muller KE, Greenham K, Kuang R. Detecting spatially co-expressed gene clusters with functional coherence by graph-regularized convolutional neural network. Bioinformatics 2022; 38:1344-1352. [PMID: 34864909 DOI: 10.1093/bioinformatics/btab812] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2021] [Revised: 10/29/2021] [Accepted: 11/29/2021] [Indexed: 01/05/2023] Open
Abstract
MOTIVATION Clustering spatial-resolved gene expression is an essential analysis to reveal gene activities in the underlying morphological context by their functional roles. However, conventional clustering analysis does not consider gene expression co-localizations in tissue for detecting spatial expression patterns or functional relationships among the genes for biological interpretation in the spatial context. In this article, we present a convolutional neural network (CNN) regularized by the graph of protein-protein interaction (PPI) network to cluster spatially resolved gene expression. This method improves the coherence of spatial patterns and provides biological interpretation of the gene clusters in the spatial context by exploiting the spatial localization by convolution and gene functional relationships by graph-Laplacian regularization. RESULTS In this study, we tested clustering the spatially variable genes or all expressed genes in the transcriptome in 22 Visium spatial transcriptomics datasets of different tissue sections publicly available from 10× Genomics and spatialLIBD. The results demonstrate that the PPI-regularized CNN constantly detects gene clusters with coherent spatial patterns and significantly enriched by gene functions with the state-of-the-art performance. Additional case studies on mouse kidney tissue and human breast cancer tissue suggest that the PPI-regularized CNN also detects spatially co-expressed genes to define the corresponding morphological context in the tissue with valuable insights. AVAILABILITY AND IMPLEMENTATION Source code is available at https://github.com/kuanglab/CNN-PReg. SUPPLEMENTARY INFORMATION Supplementary data are available at Bioinformatics online.
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Affiliation(s)
- Tianci Song
- Department of Computer Science and Engineering, University of Minnesota Twin Cities, Minneapolis, MN 55414, USA
| | - Kathleen K Markham
- Department of Plant and Microbial Biology, University of Minnesota Twin Cities, Minneapolis, MN 55414, USA
| | - Zhuliu Li
- Department of Computer Science and Engineering, University of Minnesota Twin Cities, Minneapolis, MN 55414, USA
| | - Kristen E Muller
- Department of Pathology and Laboratory Medicine, Dartmouth-Hitchcock Medical Center, Lebanon, NH 03756, USA
| | - Kathleen Greenham
- Department of Plant and Microbial Biology, University of Minnesota Twin Cities, Minneapolis, MN 55414, USA
| | - Rui Kuang
- Department of Computer Science and Engineering, University of Minnesota Twin Cities, Minneapolis, MN 55414, USA
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14
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Abstract
Small-scale trials in patients with chronic kidney disease (CKD) 3-5 have shown that hypobicarbonatemic metabolic acidosis promotes progression of CKD. Accordingly, the 2012 KDIGO (Kidney Disease: Improving Global Outcomes) guideline suggests base administration to patients with CKD when serum bicarbonate concentration ([HCO3ˉ]) is <22 mEq/L (~15% of non–dialysis-dependent patients with CKD). However, individuals with milder CKD largely maintain serum [HCO3ˉ] within the normal range (eubicarbonatemia) and yet can manifest hydrogen ion (H+) retention. Limited data in eubicarbonatemic patients with CKD 2 suggest that base administration ameliorates CKD progression. Furthermore, most patients with moderate and advanced CKD maintain a normal serum [HCO3ˉ], and of those, the vast majority most likely harbor masked H+ retention. The present review probes this expanded concept of metabolic acidosis of CKD: the eubicarbonatemic H+ retention or subclinical metabolic acidosis of CKD. It focuses on the high prevalence of the entity, its pathophysiologic features, its clinical course, and recent work on potential biomarkers of the condition. Further, it puts forward the urgent task of investigating definitively whether treatment with alkali of eubicarbonatemic H+ retention delays CKD progression. If proven true, such knowledge would trigger a paradigm shift in the indication for alkali therapy in CKD.
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Affiliation(s)
- Nicolaos E Madias
- Department of Medicine, Tufts University School of Medicine and Division of Nephrology, Department of Medicine, St. Elizabeth's Medical Center, Boston, MA
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15
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The Neuroprotective Effects of GPR4 Inhibition through the Attenuation of Caspase Mediated Apoptotic Cell Death in an MPTP Induced Mouse Model of Parkinson's Disease. Int J Mol Sci 2021; 22:ijms22094674. [PMID: 33925146 PMCID: PMC8125349 DOI: 10.3390/ijms22094674] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 04/26/2021] [Accepted: 04/27/2021] [Indexed: 11/17/2022] Open
Abstract
The proton-activated G protein-coupled receptor (GPCR) 4 (GPR4) is constitutively active at physiological pH, and GPR4 knockout protected dopaminergic neurons from caspase-dependent mitochondria-associated apoptosis. This study explored the role of GPR4 in a 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP)-treated mouse model of Parkinson's disease (PD). In mice, subchronic MPTP administration causes oxidative stress-induced apoptosis in the dopaminergic neurons of the substantia nigra pars compacta (SNpc), resulting in motor deficits. NE52-QQ57, a selective GPR4 antagonist, reduced dopaminergic neuronal loss in MPTP-treated mice, improving motor and memory functions. MPTP and NE52-QQ57 co-treatment in mice significantly decreased pro-apoptotic marker Bax protein levels and increased anti-apoptotic marker Bcl-2 protein levels in the SNpc and striatum. MPTP-induced caspase 3 activation and poly (ADP-ribose) polymerase (PARP) cleavage significantly decreased in the SNpc and striatum of mice co-treated with NE52-QQ57. MPTP and NE52-QQ57 co-treatment significantly increased tyrosine hydroxylase (TH)-positive cell numbers in the SNpc and striatum compared with MPTP alone. NE52-QQ57 and MPTP co-treatment improved rotarod and pole test-assessed motor performance and improved Y-maze test-assessed spatial memory. Our findings suggest GPR4 may represent a potential therapeutic target for PD, and GPR4 activation is involved in caspase-mediated neuronal apoptosis in the SNpc and striatum of MPTP-treated mice.
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16
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Li Z, Song T, Yong J, Kuang R. Imputation of spatially-resolved transcriptomes by graph-regularized tensor completion. PLoS Comput Biol 2021; 17:e1008218. [PMID: 33826608 PMCID: PMC8055040 DOI: 10.1371/journal.pcbi.1008218] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 04/19/2021] [Accepted: 03/19/2021] [Indexed: 12/02/2022] Open
Abstract
High-throughput spatial-transcriptomics RNA sequencing (sptRNA-seq) based on in-situ capturing technologies has recently been developed to spatially resolve transcriptome-wide mRNA expressions mapped to the captured locations in a tissue sample. Due to the low RNA capture efficiency by in-situ capturing and the complication of tissue section preparation, sptRNA-seq data often only provides an incomplete profiling of the gene expressions over the spatial regions of the tissue. In this paper, we introduce a graph-regularized tensor completion model for imputing the missing mRNA expressions in sptRNA-seq data, namely FIST, Fast Imputation of Spatially-resolved transcriptomes by graph-regularized Tensor completion. We first model sptRNA-seq data as a 3-way sparse tensor in genes (p-mode) and the (x, y) spatial coordinates (x-mode and y-mode) of the observed gene expressions, and then consider the imputation of the unobserved entries or fibers as a tensor completion problem in Canonical Polyadic Decomposition (CPD) form. To improve the imputation of highly sparse sptRNA-seq data, we also introduce a protein-protein interaction network to add prior knowledge of gene functions, and a spatial graph to capture the the spatial relations among the capture spots. The tensor completion model is then regularized by a Cartesian product graph of protein-protein interaction network and the spatial graph to capture the high-order relations in the tensor. In the experiments, FIST was tested on ten 10x Genomics Visium spatial transcriptomic datasets of different tissue sections with cross-validation among the known entries in the imputation. FIST significantly outperformed the state-of-the-art methods for single-cell RNAseq data imputation. We also demonstrate that both the spatial graph and PPI network play an important role in improving the imputation. In a case study, we further analyzed the gene clusters obtained from the imputed gene expressions to show that the imputations by FIST indeed capture the spatial characteristics in the gene expressions and reveal functions that are highly relevant to three different kinds of tissues in mouse kidney. Biological tissues are composed of different types of structurally organized cell units playing distinct functional roles. The exciting new spatial gene expression profiling methods have enabled the analysis of spatially resolved transcriptomes to understand the spatial and functional characteristics of these cells in the context of eco-environment of tissue. Due to the technical limitations, spatial transcriptomics data suffers from only sparsely measured mRNAs by in-situ capture and possibly missing spots in tissue regions that entirely failed fixing and permeabilizing RNAs. Our method, FIST (Fast Imputation of Spatially-resolved transcriptomes by graph-regularized Tensor completion), focuses on the spatial and high-sparsity nature of spatial transcriptomics data by modeling the data as a 3-way gene-by-(x, y)-location tensor and a product graph of a spatial graph and a protein-protein interaction network. Our comprehensive evaluation of FIST on ten 10x Genomics Visium spatial genomics datasets and comparison with the methods for single-cell RNA sequencing data imputation demonstrate that FIST is a better method more suitable for spatial gene expression imputation. Overall, we found FIST a useful new method for analyzing spatially resolved gene expressions based on novel modeling of spatial and functional information.
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Affiliation(s)
- Zhuliu Li
- Department of Computer Science and Engineering, University of Minnesota Twin Cities, Minneapolis, Minnesota, United States of America
| | - Tianci Song
- Department of Computer Science and Engineering, University of Minnesota Twin Cities, Minneapolis, Minnesota, United States of America
| | - Jeongsik Yong
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota Twin Cities, Minneapolis, Minnesota, United States of America
| | - Rui Kuang
- Department of Computer Science and Engineering, University of Minnesota Twin Cities, Minneapolis, Minnesota, United States of America
- * E-mail:
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17
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Eaton AF, Merkulova M, Brown D. The H +-ATPase (V-ATPase): from proton pump to signaling complex in health and disease. Am J Physiol Cell Physiol 2020; 320:C392-C414. [PMID: 33326313 PMCID: PMC8294626 DOI: 10.1152/ajpcell.00442.2020] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
A primary function of the H+-ATPase (or V-ATPase) is to create an electrochemical proton gradient across eukaryotic cell membranes, which energizes fundamental cellular processes. Its activity allows for the acidification of intracellular vesicles and organelles, which is necessary for many essential cell biological events to occur. In addition, many specialized cell types in various organ systems such as the kidney, bone, male reproductive tract, inner ear, olfactory mucosa, and more, use plasma membrane V-ATPases to perform specific activities that depend on extracellular acidification. It is, however, increasingly apparent that V-ATPases are central players in many normal and pathophysiological processes that directly influence human health in many different and sometimes unexpected ways. These include cancer, neurodegenerative diseases, diabetes, and sensory perception, as well as energy and nutrient-sensing functions within cells. This review first covers the well-established role of the V-ATPase as a transmembrane proton pump in the plasma membrane and intracellular vesicles and outlines factors contributing to its physiological regulation in different cell types. This is followed by a discussion of the more recently emerging unconventional roles for the V-ATPase, such as its role as a protein interaction hub involved in cell signaling, and the (patho)physiological implications of these interactions. Finally, the central importance of endosomal acidification and V-ATPase activity on viral infection will be discussed in the context of the current COVID-19 pandemic.
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Affiliation(s)
- Amity F Eaton
- Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - Maria Merkulova
- Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - Dennis Brown
- Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
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18
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Alevrakis E, Gialelis N, Vasileiadis I. Strong ion difference in urine: A measure of proton excretion or of the net plasma charge alteration? Acta Physiol (Oxf) 2020; 230:e13559. [PMID: 32930472 DOI: 10.1111/apha.13559] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2020] [Revised: 09/08/2020] [Accepted: 09/08/2020] [Indexed: 11/27/2022]
Affiliation(s)
| | - Nikolaos Gialelis
- Department of Mathematics National and Kapodistrian University of Athens Athens Greece
| | - Ioannis Vasileiadis
- Intensive Care Unit 1 Department of Respiratory Medicine National and Kapodistrian University of AthensSotiria Hospital Athens Greece
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19
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Alam P, Amlal S, Thakar CV, Amlal H. Acetazolamide causes renal [Formula: see text] wasting but inhibits ammoniagenesis and prevents the correction of metabolic acidosis by the kidney. Am J Physiol Renal Physiol 2020; 319:F366-F379. [PMID: 32657159 PMCID: PMC7509283 DOI: 10.1152/ajprenal.00501.2019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Revised: 07/05/2020] [Accepted: 07/06/2020] [Indexed: 11/22/2022] Open
Abstract
Carbonic anhydrase (CAII) binds to the electrogenic basolateral Na+-[Formula: see text] cotransporter (NBCe1) and facilitates [Formula: see text] reabsorption across the proximal tubule. However, whether the inhibition of CAII with acetazolamide (ACTZ) alters NBCe1 activity and interferes with the ammoniagenesis pathway remains elusive. To address this issue, we compared the renal adaptation of rats treated with ACTZ to NH4Cl loading for up to 2 wk. The results indicated that ACTZ-treated rats exhibited a sustained metabolic acidosis for up to 2 wk, whereas in NH4Cl-loaded rats, metabolic acidosis was corrected within 2 wk of treatment. [Formula: see text] excretion increased by 10-fold in NH4Cl-loaded rats but only slightly (1.7-fold) in ACTZ-treated rats during the first week despite a similar degree of acidosis. Immunoblot experiments showed that the protein abundance of glutaminase (4-fold), glutamate dehydrogenase (6-fold), and SN1 (8-fold) increased significantly in NH4Cl-loaded rats but remained unchanged in ACTZ-treated rats. Na+/H+ exchanger 3 and NBCe1 proteins were upregulated in response to NH4Cl loading but not ACTZ treatment and were rather sharply downregulated after 2 wk of ACTZ treatment. ACTZ causes renal [Formula: see text] wasting and induces metabolic acidosis but inhibits the upregulation of glutamine transporter and ammoniagenic enzymes and thus suppresses ammonia synthesis and secretion in the proximal tubule, which prevented the correction of acidosis. This effect is likely mediated through the inhibition of the CA-NBCe1 metabolon complex, which results in cell alkalinization. During chronic ACTZ treatment, the downregulation of both NBCe1 and Na+/H+ exchanger 3, along with the inhibition of ammoniagenesis and [Formula: see text] generation, contributes to the maintenance of metabolic acidosis.
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Affiliation(s)
- Perwez Alam
- Division of Nephrology and Kidney C.A.R.E, Department of Internal Medicine, University of Cincinnati, Cincinnati, Ohio
- Department of Pathology and Laboratory Medicine, College of Medicine, University of Cincinnati, Cincinnati, Ohio
| | - Sihame Amlal
- Division of Nephrology and Kidney C.A.R.E, Department of Internal Medicine, University of Cincinnati, Cincinnati, Ohio
| | - Charuhas V Thakar
- Division of Nephrology and Kidney C.A.R.E, Department of Internal Medicine, University of Cincinnati, Cincinnati, Ohio
| | - Hassane Amlal
- Division of Nephrology and Kidney C.A.R.E, Department of Internal Medicine, University of Cincinnati, Cincinnati, Ohio
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20
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Chen Z, Peng H, Zhang C. Advances in kidney-targeted drug delivery systems. Int J Pharm 2020; 587:119679. [PMID: 32717283 DOI: 10.1016/j.ijpharm.2020.119679] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2020] [Revised: 06/28/2020] [Accepted: 07/18/2020] [Indexed: 12/19/2022]
Abstract
The management and treatment of kidney diseases currently have caused a huge global burden. Although the application of nanotechnology for the therapy of kidney diseases is still at an early stages, it has profound potential of development. More and more nano-based drug delivery systems provide novel solutions for the treatment of kidney diseases. This article summarizes the physiological and anatomical properties of the kidney and the biological and physicochemical characters of drug delivery systems, which affects the ability of drug to target the kidney, and highlights the prospects, opportunities, and challenges of nanotechnology in the therapy of kidney diseases.
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Affiliation(s)
- Zhong Chen
- Department of Pharmaceutics, Daqing Campus of Harbin Medical University, 1 Xinyang Rd, Daqing 163319, China
| | - Haisheng Peng
- Department of Pharmaceutics, Daqing Campus of Harbin Medical University, 1 Xinyang Rd, Daqing 163319, China.
| | - Changmei Zhang
- Department of Pharmaceutics, Daqing Campus of Harbin Medical University, 1 Xinyang Rd, Daqing 163319, China.
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21
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Chen Y, Wu G, Chen L, Tong L, Lei Y, Shen L, Jiao T, Li H. Selective Recognition of Chloride Anion in Water. Org Lett 2020; 22:4878-4882. [PMID: 32496778 DOI: 10.1021/acs.orglett.0c01722] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
A tricationic cage was synthesized via click chemistry. The cage has a preorganized cavity, which is surrounded by six relatively acidic C-H bonds. In organic solvent, the cage can recognize a variety of anions, among which the Cl- anion has the highest binding affinity due to size selectivity. The cage is also able to selectively recognize the Cl- anion in water, even though the binding affinity is just moderate.
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Affiliation(s)
- Yixin Chen
- Department of Chemistry, Zhejiang University, Hangzhou 310027, China
| | - Guangcheng Wu
- Department of Chemistry, Zhejiang University, Hangzhou 310027, China
| | - Liang Chen
- Department of Chemistry, Zhejiang University, Hangzhou 310027, China
| | - Lu Tong
- Department of Chemistry, Zhejiang University, Hangzhou 310027, China
| | - Ye Lei
- Department of Chemistry, Zhejiang University, Hangzhou 310027, China
| | - Libo Shen
- Department of Chemistry, Zhejiang University, Hangzhou 310027, China
| | - Tianyu Jiao
- Department of Chemistry, Zhejiang University, Hangzhou 310027, China
| | - Hao Li
- Department of Chemistry, Zhejiang University, Hangzhou 310027, China
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22
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Abstract
Acid-base balance is critical for normal life. Acute and chronic disturbances impact cellular energy metabolism, endocrine signaling, ion channel activity, neuronal activity, and cardiovascular functions such as cardiac contractility and vascular blood flow. Maintenance and adaptation of acid-base homeostasis are mostly controlled by respiration and kidney. The kidney contributes to acid-base balance by reabsorbing filtered bicarbonate, regenerating bicarbonate through ammoniagenesis and generation of protons, and by excreting acid. This review focuses on acid-base disorders caused by renal processes, both inherited and acquired. Distinct rare inherited monogenic diseases affecting acid-base handling in the proximal tubule and collecting duct have been identified. In the proximal tubule, mutations of solute carrier 4A4 (SLC4A4) (electrogenic Na+/HCO3--cotransporter Na+/bicarbonate cotransporter e1 [NBCe1]) and other genes such as CLCN5 (Cl-/H+-antiporter), SLC2A2 (GLUT2 glucose transporter), or EHHADH (enoyl-CoA, hydratase/3-hydroxyacyl CoA dehydrogenase) causing more generalized proximal tubule dysfunction can cause proximal renal tubular acidosis resulting from bicarbonate wasting and reduced ammoniagenesis. Mutations in adenosine triphosphate ATP6V1 (B1 H+-ATPase subunit), ATPV0A4 (a4 H+-ATPase subunit), SLC4A1 (anion exchanger 1), and FOXI1 (forkhead transcription factor) cause distal renal tubular acidosis type I. Carbonic anhydrase II mutations affect several nephron segments and give rise to a mixed proximal and distal phenotype. Finally, mutations in genes affecting aldosterone synthesis, signaling, or downstream targets can lead to hyperkalemic variants of renal tubular acidosis (type IV). More common forms of renal acidosis are found in patients with advanced stages of chronic kidney disease and are owing, at least in part, to a reduced capacity for ammoniagenesis.
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Affiliation(s)
- Carsten A Wagner
- Institute of Physiology, University of Zurich, Zurich, Switzerland; National Center for Competence in Research Kidney, Switzerland.
| | - Pedro H Imenez Silva
- Institute of Physiology, University of Zurich, Zurich, Switzerland; National Center for Competence in Research Kidney, Switzerland
| | - Soline Bourgeois
- Institute of Physiology, University of Zurich, Zurich, Switzerland; National Center for Competence in Research Kidney, Switzerland
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23
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Wesson DE, Buysse JM, Bushinsky DA. Mechanisms of Metabolic Acidosis-Induced Kidney Injury in Chronic Kidney Disease. J Am Soc Nephrol 2020; 31:469-482. [PMID: 31988269 DOI: 10.1681/asn.2019070677] [Citation(s) in RCA: 101] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Retrospective analyses and single-center prospective studies identify chronic metabolic acidosis as an independent and modifiable risk factor for progression of CKD. In patients with CKD, untreated chronic metabolic acidosis often leads to an accelerated reduction in GFR. Mechanisms responsible for this reduction include adaptive responses that increase acid excretion but lead to a decline in kidney function. Metabolic acidosis in CKD stimulates production of intrakidney paracrine hormones including angiotensin II, aldosterone, and endothelin-1 (ET-1) that mediate the immediate benefit of increased kidney acid excretion, but their chronic upregulation promotes inflammation and fibrosis. Chronic metabolic acidosis also stimulates ammoniagenesis that increases acid excretion but also leads to ammonia-induced complement activation and deposition of C3 and C5b-9 that can cause tubule-interstitial damage, further worsening disease progression. These effects, along with acid accumulation in kidney tissue, combine to accelerate progression of kidney disease. Treatment of chronic metabolic acidosis attenuates these adaptive responses; reduces levels of angiotensin II, aldosterone, and ET-1; reduces ammoniagenesis; and diminishes inflammation and fibrosis that may lead to slowing of CKD progression.
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Affiliation(s)
- Donald E Wesson
- Baylor Scott & White Health and Wellness Center, Dallas, Texas; .,Department of Internal Medicine, Texas A&M College of Medicine, Bryan, Texas
| | | | - David A Bushinsky
- Division of Nephrology, University of Rochester School of Medicine, Rochester, New York
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24
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The Role of the Primary Cilium in Sensing Extracellular pH. Cells 2019; 8:cells8070704. [PMID: 31336778 PMCID: PMC6679169 DOI: 10.3390/cells8070704] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Revised: 07/08/2019] [Accepted: 07/09/2019] [Indexed: 12/12/2022] Open
Abstract
Biosensors on the membrane of the vascular endothelium are responsible for sensing mechanical and chemical signals in the blood. Transduction of these stimuli into intracellular signaling cascades regulate cellular processes including ion transport, gene expression, cell proliferation, and/or cell death. The primary cilium is a well-known biosensor of shear stress but its role in sensing extracellular pH change has never been examined. As a cellular extension into the immediate microenvironment, the cilium could be a prospective sensor for changes in pH and regulator of acid response in cells. We aim to test our hypothesis that the primary cilium plays the role of an acid sensor in cells using vascular endothelial and embryonic fibroblast cells as in vitro models. We measure changes in cellular pH using pH-sensitive 2',7'-biscarboxyethy1-5,6-carboxyfluorescein acetoxy-methylester (BCECF) fluorescence and mitogen-activated protein kinase (MAPK) activity to quantify responses to both extracellular pH (pHo) and intracellular pH (pHi) changes. Our studies show that changes in pHo affect pHi in both wild-type and cilia-less Tg737 cells and that the kinetics of the pHi response are similar in both cells. Acidic pHo or pHi was observed to change the length of primary cilia in wild-type cells while the cilia in Tg737 remained absent. Vascular endothelial cells respond to acidic pH through activation of ERK1/2 and p38-mediated signaling pathways. The cilia-less Tg737 cells exhibit delayed responsiveness to pHo dependent and independent pHi acidification as depicted in the phosphorylation profile of ERK1/2 and p38. Otherwise, intracellular pH homeostatic response to acidic pHo is similar between wild-type and Tg737 cells, indicating that the primary cilia may not be the sole sensor for physiological pH changes. These endothelial cells respond to pH changes with a predominantly K+-dependent pHi recovery mechanism, regardless of ciliary presence or absence.
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25
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Lashhab R, Ullah AS, Cordat E. Renal collecting duct physiology and pathophysiology. Biochem Cell Biol 2019; 97:234-242. [DOI: 10.1139/bcb-2018-0192] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Affiliation(s)
- Rawad Lashhab
- Department of Physiology and Membrane Protein and Disease Research Group, University of Alberta, Edmonton, AB T6G 2H7, Canada
- Department of Physiology and Membrane Protein and Disease Research Group, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - A.K.M. Shahid Ullah
- Department of Physiology and Membrane Protein and Disease Research Group, University of Alberta, Edmonton, AB T6G 2H7, Canada
- Department of Physiology and Membrane Protein and Disease Research Group, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Emmanuelle Cordat
- Department of Physiology and Membrane Protein and Disease Research Group, University of Alberta, Edmonton, AB T6G 2H7, Canada
- Department of Physiology and Membrane Protein and Disease Research Group, University of Alberta, Edmonton, AB T6G 2H7, Canada
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26
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Giesecke T, Himmerkus N, Leipziger J, Bleich M, Koshimizu TA, Fähling M, Smorodchenko A, Shpak J, Knappe C, Isermann J, Ayasse N, Kawahara K, Schmoranzer J, Gimber N, Paliege A, Bachmann S, Mutig K. Vasopressin Increases Urinary Acidification via V1a Receptors in Collecting Duct Intercalated Cells. J Am Soc Nephrol 2019; 30:946-961. [PMID: 31097611 DOI: 10.1681/asn.2018080816] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2018] [Accepted: 03/11/2019] [Indexed: 01/30/2023] Open
Abstract
BACKGROUND Antagonists of the V1a vasopressin receptor (V1aR) are emerging as a strategy for slowing progression of CKD. Physiologically, V1aR signaling has been linked with acid-base homeostasis, but more detailed information is needed about renal V1aR distribution and function. METHODS We used a new anti-V1aR antibody and high-resolution microscopy to investigate Va1R distribution in rodent and human kidneys. To investigate whether V1aR activation promotes urinary H+ secretion, we used a V1aR agonist or antagonist to evaluate V1aR function in vasopressin-deficient Brattleboro rats, bladder-catheterized mice, isolated collecting ducts, and cultured inner medullary collecting duct (IMCD) cells. RESULTS Localization of V1aR in rodent and human kidneys produced a basolateral signal in type A intercalated cells (A-ICs) and a perinuclear to subapical signal in type B intercalated cells of connecting tubules and collecting ducts. Treating vasopressin-deficient Brattleboro rats with a V1aR agonist decreased urinary pH and tripled net acid excretion; we observed a similar response in C57BL/6J mice. In contrast, V1aR antagonist did not affect urinary pH in normal or acid-loaded mice. In ex vivo settings, basolateral treatment of isolated perfused medullary collecting ducts with the V1aR agonist or vasopressin increased intracellular calcium levels in ICs and decreased luminal pH, suggesting V1aR-dependent calcium release and stimulation of proton-secreting proteins. Basolateral treatment of IMCD cells with the V1aR agonist increased apical abundance of vacuolar H+-ATPase in A-ICs. CONCLUSIONS Our results show that activation of V1aR contributes to urinary acidification via H+ secretion by A-ICs, which may have clinical implications for pharmacologic targeting of V1aR.
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Affiliation(s)
- Torsten Giesecke
- Institute of Vegetative Anatomy, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany; .,Berlin Institute of Health (BIH), Berlin, Germany
| | - Nina Himmerkus
- Institute of Physiology, Christian-Albrechts-Universität zu Kiel, Kiel, Germany
| | - Jens Leipziger
- Department of Biomedicine, Aarhus University, Aarhus C, Denmark
| | - Markus Bleich
- Institute of Physiology, Christian-Albrechts-Universität zu Kiel, Kiel, Germany
| | - Taka-Aki Koshimizu
- Division of Molecular Pharmacology, Department of Pharmacology, Jichi Medical University, Shimotsuke-shi, Tochigi-ken, Japan
| | - Michael Fähling
- Institute of Vegetative Physiology, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Alina Smorodchenko
- Institute of Vegetative Anatomy, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Julia Shpak
- Institute of Vegetative Anatomy, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Carolin Knappe
- Institute of Vegetative Anatomy, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Julian Isermann
- Institute of Physiology, Christian-Albrechts-Universität zu Kiel, Kiel, Germany
| | - Niklas Ayasse
- Department of Biomedicine, Aarhus University, Aarhus C, Denmark
| | - Katsumasa Kawahara
- Department of Physiology, Kitasato University School of Medicine, Sagamihara, Kanagawa, Japan
| | - Jan Schmoranzer
- Advanced Medical BioImaging Core Facility, Charite-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Niclas Gimber
- Advanced Medical BioImaging Core Facility, Charite-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Alexander Paliege
- Division of Nephrology, Department of Internal Medicine III, University Hospital Carl Gustav Carus at the Technische Universität Dresden, Dresden, Germany; and
| | - Sebastian Bachmann
- Institute of Vegetative Anatomy, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Kerim Mutig
- Institute of Vegetative Anatomy, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany; .,Department of Pharmacology, I.M. Sechenov First Moscow State Medical University of the Ministry of Healthcare of the Russian Federation (Sechenovskiy University), Moscow, Russian Federation
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Sodium Citrate Increases Expression and Flux of Mg 2+ Transport Carriers Mediated by Activation of MEK/ERK/c-Fos Pathway in Renal Tubular Epithelial Cells. Nutrients 2018; 10:nu10101345. [PMID: 30241394 PMCID: PMC6213502 DOI: 10.3390/nu10101345] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Revised: 09/19/2018] [Accepted: 09/19/2018] [Indexed: 01/12/2023] Open
Abstract
A chronic magnesium deficiency may be one of the causes of lifestyle-related diseases such as hypertension and diabetes. Serum Mg2+ concentration is strictly controlled by the reabsorption pathway in the renal tubules, but little is known about how Mg2+ reabsorption is upregulated. We searched for food compounds which can increase the expression levels of Mg2+ transport carriers including transient receptor potential melastatin 6 (TRPM6) channel and cyclin M2 (CNNM2). Sodium citrate (SC) increased the mRNA levels of TRPM6 and CNNM2 in renal tubular epithelial NRK-52E cells. The SC-induced elevation of TRPM6 was inhibited by U0126, a mitogen-activated protein kinase kinase (MEK) inhibitor, but the CNNM2 was not. SC increased the levels of p-ERK1/2 and p-c-Fos, which were inhibited by U0126. SC induced alkalization of culture medium. Both SC and alkalization enhanced Mg2+ influx, which was inhibited by U0126 and introduction of TRPM6 siRNA. The reporter activity of TRPM6 was increased by SC and alkalization, which was suppressed by mutation in an AP-1-binding site. The SC-induced elevation of p-ERK1/2 and p-EGFR was inhibited by diphenylene iodonium, a nicotinamide adenine dinucleotide phosphate (NADPH) oxidase inhibitor, and erlotinib, an epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor. SC did not change the level of acetyl histone H3, but increased the association of c-Fos with the promoter region of TRPM6. These results suggest that SC increases TRPM6 expression and Mg2+ influx mediated by the activation of NADPH oxidase and an EGFR/ERK/c-Fos pathway in the renal tubules.
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28
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Adenylyl cyclase 6 in acid-base balance - adding complexity. Clin Sci (Lond) 2018; 132:1995-1997. [PMID: 30220652 DOI: 10.1042/cs20180572] [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: 08/02/2018] [Revised: 08/14/2018] [Accepted: 08/16/2018] [Indexed: 11/17/2022]
Abstract
Systemic acid-base balance is tightly controlled within a narrow range of pH. Disturbances in systemic acid-base homeostasis are associated with diverse detrimental effects. The kidney is a key regulator of acid-base balance, capable of excreting HCO3- or H+, and chronic kidney disease invariably leads to acidosis. However, the regulatory pathways underlying the fine-tuned acid-base sensing and regulatory mechanisms are still incompletely understood. In the article published recently in Clinical Science (vol 132 (16) 1779-1796), Poulson and colleagues investigated the role of adenylyl cyclase 6 (AC6) in acid-base homeostasis. They uncovered a complex role of AC6, specifically affecting acid-base balance during HCO3- load, which causes pronounced alkalosis in AC6-deficient mice. However, the phenotype of AC6-deficient mice appears much more complex, involving systemic effects associated with increased energy expenditure. These observations remind us that there is much to be learned about the intricate signaling pathways involved in renal control of acid-base balance and the complex ramifications of acid-base regulation.
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29
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Hosford PS, Mosienko V, Kishi K, Jurisic G, Seuwen K, Kinzel B, Ludwig MG, Wells JA, Christie IN, Koolen L, Abdala AP, Liu BH, Gourine AV, Teschemacher AG, Kasparov S. CNS distribution, signalling properties and central effects of G-protein coupled receptor 4. Neuropharmacology 2018; 138:381-392. [PMID: 29894771 PMCID: PMC6063991 DOI: 10.1016/j.neuropharm.2018.06.007] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Revised: 06/04/2018] [Accepted: 06/05/2018] [Indexed: 12/14/2022]
Abstract
Information on the distribution and biology of the G-protein coupled receptor 4 (GPR4) in the brain is limited. It is currently thought that GPR4 couples to Gs proteins and may mediate central respiratory sensitivity to CO2. Using a knock-in mouse model, abundant GPR4 expression was detected in the cerebrovascular endothelium and neurones of dorsal raphe, retro-trapezoidal nucleus locus coeruleus and lateral septum. A similar distribution was confirmed using RNAscope in situ hybridisation. In HEK293 cells, overexpressing GPR4, it was highly constitutively active at neutral pH with little further increase in cAMP towards acidic pH. The GPR4 antagonist NE 52-QQ57 effectively blocked GPR4-mediated cAMP accumulation (IC50 26.8 nM in HEK293 cells). In HUVEC which natively express GPR4, physiological acidification (pH 7.4-7.0) resulted in a cAMP increase by ∼55% which was completely prevented by 1 μM NE 52-QQ57. The main extracellular organic acid, l-lactic acid (LL; 1-10 mM), suppressed pH dependent activation of GPR4 in HEK293 and HUVEC cells, suggesting allosteric negative modulation. In unanaesthetised mice and rats, NE 52-QQ57 (20 mg kg-1) reduced ventilatory response to 5 and 10% CO2. In anaesthetised rats, systemic administration of NE 52-QQ57 (up to 20 mg kg-1) had no effect on hemodynamics, cerebral blood flow and blood oxygen level dependent responses. Central administration of NE 52-QQ57 (1 mM) in vagotomised anaesthetised rats did not affect CO2-induced respiratory responses. Our results indicate that GPR4 is expressed by multiple neuronal populations and endothelium and that its pH sensitivity is affected by level of expression and LL. NE 52-QQ57 blunts hypercapnic response to CO2 but this effect is absent under anaesthesia, possibly due to the inhibitory effect of LL on GPR4.
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Affiliation(s)
- P S Hosford
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology and Pharmacology, University College London, WC1E 6BT, UK
| | - V Mosienko
- Physiology, Pharmacology and Neuroscience, University of Bristol, BS8 1TD, UK
| | - K Kishi
- Physiology, Pharmacology and Neuroscience, University of Bristol, BS8 1TD, UK
| | - G Jurisic
- Novartis Institutes for Biomedical Research, CH-4002 Basel, Switzerland
| | - K Seuwen
- Novartis Institutes for Biomedical Research, CH-4002 Basel, Switzerland
| | - B Kinzel
- Novartis Institutes for Biomedical Research, CH-4002 Basel, Switzerland
| | - M G Ludwig
- Novartis Institutes for Biomedical Research, CH-4002 Basel, Switzerland
| | - J A Wells
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology and Pharmacology, University College London, WC1E 6BT, UK
| | - I N Christie
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology and Pharmacology, University College London, WC1E 6BT, UK
| | - L Koolen
- Physiology, Pharmacology and Neuroscience, University of Bristol, BS8 1TD, UK
| | - A P Abdala
- Physiology, Pharmacology and Neuroscience, University of Bristol, BS8 1TD, UK
| | - B H Liu
- Physiology, Pharmacology and Neuroscience, University of Bristol, BS8 1TD, UK
| | - A V Gourine
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology and Pharmacology, University College London, WC1E 6BT, UK
| | - A G Teschemacher
- Physiology, Pharmacology and Neuroscience, University of Bristol, BS8 1TD, UK.
| | - S Kasparov
- Physiology, Pharmacology and Neuroscience, University of Bristol, BS8 1TD, UK; Baltic Federal University, Kaliningrad 236041, Russian Federation.
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30
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Wang Y, de Vallière C, Imenez Silva PH, Leonardi I, Gruber S, Gerstgrasser A, Melhem H, Weber A, Leucht K, Wolfram L, Hausmann M, Krieg C, Thomasson K, Boyman O, Frey-Wagner I, Rogler G, Wagner CA. The Proton-activated Receptor GPR4 Modulates Intestinal Inflammation. J Crohns Colitis 2018; 12:355-368. [PMID: 29136128 DOI: 10.1093/ecco-jcc/jjx147] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/25/2016] [Accepted: 11/02/2017] [Indexed: 12/12/2022]
Abstract
BACKGROUND AND AIMS During active inflammation, intraluminal intestinal pH is decreased in patients with inflammatory bowel disease [IBD]. Acidic pH may play a role in IBD pathophysiology. Recently, proton-sensing G-protein coupled receptors were identified, including GPR4, OGR1 [GPR68], and TDAG8 [GPR65]. We investigated whether GPR4 is involved in intestinal inflammation. METHODS The role of GPR4 was assessed in murine colitis models by chronic dextran sulphate sodium [DSS] administration and by cross-breeding into an IL-10 deficient background for development of spontaneous colitis. Colitis severity was assessed by body weight, colonoscopy, colon length, histological score, cytokine mRNA expression, and myeloperoxidase [MPO] activity. In the spontaneous Il-10-/- colitis model, the incidence of rectal prolapse and characteristics of lamina propria leukocytes [LPLs] were analysed. RESULTS Gpr4-/- mice showed reduced body weight loss and histology score after induction of chronic DSS colitis. In Gpr4-/-/Il-10-/- double knock-outs, the onset and progression of rectal prolapse were significantly delayed and mitigated compared with Gpr4+/+/Il-10-/- mice. Double knock-out mice showed lower histology scores, MPO activity, CD4+ T helper cell infiltration, IFN-γ, iNOS, MCP-1 [CCL2], CXCL1, and CXCL2 expression compared with controls. In colon, GPR4 mRNA was detected in endothelial cells, some smooth muscle cells, and some macrophages. CONCLUSIONS Absence of GPR4 ameliorates colitis in IBD animal models, indicating an important regulatory role in mucosal inflammation, thus providing a new link between tissue pH and the immune system. Therapeutic inhibition of GPR4 may be beneficial for the treatment of IBD.
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Affiliation(s)
- Yu Wang
- Department of Gastroenterology and Hepatology, University Hospital Zurich, Zurich, Switzerland.,Institute of Physiology, University of Zurich, Zurich, Switzerland
| | - Cheryl de Vallière
- Department of Gastroenterology and Hepatology, University Hospital Zurich, Zurich, Switzerland
| | | | - Irina Leonardi
- Department of Gastroenterology and Hepatology, University Hospital Zurich, Zurich, Switzerland
| | - Sven Gruber
- Department of Gastroenterology and Hepatology, University Hospital Zurich, Zurich, Switzerland.,Institute of Physiology, University of Zurich, Zurich, Switzerland
| | - Alexandra Gerstgrasser
- Department of Gastroenterology and Hepatology, University Hospital Zurich, Zurich, Switzerland
| | - Hassan Melhem
- Department of Gastroenterology and Hepatology, University Hospital Zurich, Zurich, Switzerland
| | - Achim Weber
- Institute of Surgical Pathology, University Hospital Zurich, Zurich, Switzerland
| | - Katharina Leucht
- Department of Gastroenterology and Hepatology, University Hospital Zurich, Zurich, Switzerland
| | - Lutz Wolfram
- Department of Gastroenterology and Hepatology, University Hospital Zurich, Zurich, Switzerland
| | - Martin Hausmann
- Department of Gastroenterology and Hepatology, University Hospital Zurich, Zurich, Switzerland
| | - Carsten Krieg
- Laboratory of Applied Immunobiology, University of Zurich, Zurich, Switzerland.,Institute of Experimental Immunology, University of Zurich, Zurich, Switzerland
| | - Koray Thomasson
- Laboratory of Applied Immunobiology, University of Zurich, Zurich, Switzerland
| | - Onur Boyman
- Laboratory of Applied Immunobiology, University of Zurich, Zurich, Switzerland.,Department of Immunology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Isabelle Frey-Wagner
- Department of Gastroenterology and Hepatology, University Hospital Zurich, Zurich, Switzerland
| | - Gerhard Rogler
- Department of Gastroenterology and Hepatology, University Hospital Zurich, Zurich, Switzerland.,Institute of Physiology, University of Zurich, Zurich, Switzerland
| | - Carsten A Wagner
- Institute of Physiology, University of Zurich, Zurich, Switzerland
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31
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Battistone MA, Nair AV, Barton CR, Liberman RN, Peralta MA, Capen DE, Brown D, Breton S. Extracellular Adenosine Stimulates Vacuolar ATPase-Dependent Proton Secretion in Medullary Intercalated Cells. J Am Soc Nephrol 2017; 29:545-556. [PMID: 29222395 DOI: 10.1681/asn.2017060643] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Accepted: 10/18/2017] [Indexed: 12/29/2022] Open
Abstract
Acidosis is an important complication of AKI and CKD. Renal intercalated cells (ICs) express the proton pumping vacuolar H+-ATPase (V-ATPase) and are extensively involved in acid-base homeostasis. H+ secretion in type A intercalated cells (A-ICs) is regulated by apical vesicle recycling and stimulated by cAMP. In other cell types, cAMP is increased by extracellular agonists, including adenosine, through purinergic receptors. Adenosine is a Food and Drug Administration-approved drug, but very little is known about the effect of adenosine on IC function. Therefore, we investigated the role of adenosine in the regulation of V-ATPase in ICs. Intravenous treatment of mice with adenosine or agonists of ADORA2A and ADORA2B purinergic P1 receptors induced V-ATPase apical membrane accumulation in medullary A-ICs but not in cortical A-ICs or other IC subtypes. Both receptors are located in A-IC apical membranes, and adenosine injection increased urine adenosine concentration and decreased urine pH. Cell fractionation showed that adenosine or an ADORA2A or ADORA2B agonist induced V-ATPase translocation from vesicles to the plasma membrane and increased protein kinase A (PKA)-dependent protein phosphorylation in purified medullary ICs that were isolated from mice. Either ADORA2A or ADORA2B antagonists or the PKA inhibitor mPKI blocked these effects. Finally, a fluorescence pH assay showed that adenosine activates V-ATPase in isolated medullary ICs. Our study shows that medullary A-ICs respond to luminal adenosine through ADORA2A and ADORA2B receptors in a cAMP/PKA pathway-dependent mechanism to induce V-ATPase-dependent H+ secretion.
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Affiliation(s)
- Maria A Battistone
- Program in Membrane Biology, Center for Systems Biology, Nephrology Division, and Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | - Anil V Nair
- Program in Membrane Biology, Center for Systems Biology, Nephrology Division, and Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | - Claire R Barton
- Program in Membrane Biology, Center for Systems Biology, Nephrology Division, and Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | - Rachel N Liberman
- Program in Membrane Biology, Center for Systems Biology, Nephrology Division, and Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | - Maria A Peralta
- Program in Membrane Biology, Center for Systems Biology, Nephrology Division, and Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | - Diane E Capen
- Program in Membrane Biology, Center for Systems Biology, Nephrology Division, and Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | - Dennis Brown
- Program in Membrane Biology, Center for Systems Biology, Nephrology Division, and Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | - Sylvie Breton
- Program in Membrane Biology, Center for Systems Biology, Nephrology Division, and Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
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32
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Mulugeta E, He Q, Sareen D, Hong SJ, Oh JH, Lynch VM, Sessler JL, Kim SK, Lee CH. Recognition, Sensing, and Trapping of Bicarbonate Anions with a Dicationic meso-Bis(benzimidazolium) Calix[4]pyrrole. Chem 2017. [DOI: 10.1016/j.chempr.2017.10.007] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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33
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Liu J, Kumar S, Dolzhenko E, Alvarado GF, Guo J, Lu C, Chen Y, Li M, Dessing MC, Parvez RK, Cippà PE, Krautzberger AM, Saribekyan G, Smith AD, McMahon AP. Molecular characterization of the transition from acute to chronic kidney injury following ischemia/reperfusion. JCI Insight 2017; 2:94716. [PMID: 28931758 PMCID: PMC5612583 DOI: 10.1172/jci.insight.94716] [Citation(s) in RCA: 180] [Impact Index Per Article: 25.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Accepted: 08/10/2017] [Indexed: 12/16/2022] Open
Abstract
Though an acute kidney injury (AKI) episode is associated with an increased risk of chronic kidney disease (CKD), the mechanisms determining the transition from acute to irreversible chronic injury are not well understood. To extend our understanding of renal repair, and its limits, we performed a detailed molecular characterization of a murine ischemia/reperfusion injury (IRI) model for 12 months after injury. Together, the data comprising RNA-sequencing (RNA-seq) analysis at multiple time points, histological studies, and molecular and cellular characterization of targeted gene activity provide a comprehensive profile of injury, repair, and long-term maladaptive responses following IRI. Tubular atrophy, interstitial fibrosis, inflammation, and development of multiple renal cysts were major long-term outcomes of IRI. Progressive proximal tubular injury tracks with de novo activation of multiple Krt genes, including Krt20, a biomarker of renal tubule injury. RNA-seq analysis highlights a cascade of temporal-specific gene expression patterns related to tubular injury/repair, fibrosis, and innate and adaptive immunity. Intersection of these data with human kidney transplant expression profiles identified overlapping gene expression signatures correlating with different stages of the murine IRI response. The comprehensive characterization of incomplete recovery after ischemic AKI provides a valuable resource for determining the underlying pathophysiology of human CKD.
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Affiliation(s)
- Jing Liu
- Department of Stem Cell Biology and Regenerative Medicine, Keck School of Medicine of the University of Southern California, Los Angeles, California, USA
| | - Sanjeev Kumar
- Department of Stem Cell Biology and Regenerative Medicine, Keck School of Medicine of the University of Southern California, Los Angeles, California, USA.,Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Egor Dolzhenko
- Molecular and Computational Biology, Division of Biological Sciences, University of Southern California, Los Angeles, California, USA
| | - Gregory F Alvarado
- Department of Stem Cell Biology and Regenerative Medicine, Keck School of Medicine of the University of Southern California, Los Angeles, California, USA
| | - Jinjin Guo
- Department of Stem Cell Biology and Regenerative Medicine, Keck School of Medicine of the University of Southern California, Los Angeles, California, USA
| | - Can Lu
- Department of Stem Cell Biology and Regenerative Medicine, Keck School of Medicine of the University of Southern California, Los Angeles, California, USA
| | - Yibu Chen
- Norris Medical Library, University of Southern California, Los Angeles, California
| | - Meng Li
- Norris Medical Library, University of Southern California, Los Angeles, California
| | - Mark C Dessing
- Department of Stem Cell Biology and Regenerative Medicine, Keck School of Medicine of the University of Southern California, Los Angeles, California, USA
| | - Riana K Parvez
- Department of Stem Cell Biology and Regenerative Medicine, Keck School of Medicine of the University of Southern California, Los Angeles, California, USA
| | - Pietro E Cippà
- Department of Stem Cell Biology and Regenerative Medicine, Keck School of Medicine of the University of Southern California, Los Angeles, California, USA
| | - A Michaela Krautzberger
- Department of Stem Cell Biology and Regenerative Medicine, Keck School of Medicine of the University of Southern California, Los Angeles, California, USA
| | - Gohar Saribekyan
- Department of Stem Cell Biology and Regenerative Medicine, Keck School of Medicine of the University of Southern California, Los Angeles, California, USA
| | - Andrew D Smith
- Molecular and Computational Biology, Division of Biological Sciences, University of Southern California, Los Angeles, California, USA
| | - Andrew P McMahon
- Department of Stem Cell Biology and Regenerative Medicine, Keck School of Medicine of the University of Southern California, Los Angeles, California, USA
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34
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Varga G, DenBesten P, Rácz R, Zsembery Á. Importance of bicarbonate transport in pH control during amelogenesis - need for functional studies. Oral Dis 2017; 24:879-890. [PMID: 28834043 DOI: 10.1111/odi.12738] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Accepted: 08/13/2017] [Indexed: 12/27/2022]
Abstract
Dental enamel, the hardest mammalian tissue, is produced by ameloblasts. Ameloblasts show many similarities to other transporting epithelia although their secretory product, the enamel matrix, is quite different. Ameloblasts direct the formation of hydroxyapatite crystals, which liberate large quantities of protons that then need to be buffered to allow mineralization to proceed. Buffering requires a tight pH regulation and secretion of bicarbonate by ameloblasts. Many investigations have used immunohistochemical and knockout studies to determine the effects of these genes on enamel formation, but up till recently very little functional data were available for mineral ion transport. To address this, we developed a novel 2D in vitro model using HAT-7 ameloblast cells. HAT-7 cells can be polarized and develop functional tight junctions. Furthermore, they are able to accumulate bicarbonate ions from the basolateral to the apical fluid spaces. We propose that in the future, the HAT-7 2D system along with similar cellular models will be useful to functionally model ion transport processes during amelogenesis. Additionally, we also suggest that similar approaches will allow a better understanding of the regulation of the cycling process in maturation-stage ameloblasts, and the pH sensory mechanisms, which are required to develop sound, healthy enamel.
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Affiliation(s)
- G Varga
- Department of Oral Biology, Semmelweis University, Budapest, Hungary
| | - P DenBesten
- Department of Orofacial Sciences, University of California, San Francisco, CA, USA
| | - R Rácz
- Department of Oral Biology, Semmelweis University, Budapest, Hungary
| | - Á Zsembery
- Department of Oral Biology, Semmelweis University, Budapest, Hungary
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35
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Stegbauer J, Chen D, Herrera M, Sparks MA, Yang T, Königshausen E, Gurley SB, Coffman TM. Resistance to hypertension mediated by intercalated cells of the collecting duct. JCI Insight 2017; 2:e92720. [PMID: 28405625 DOI: 10.1172/jci.insight.92720] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The renal collecting duct (CD), as the terminal segment of the nephron, is responsible for the final adjustments to the amount of sodium excreted in urine. While angiotensin II modulates reabsorptive functions of the CD, the contribution of these actions to physiological homeostasis is not clear. To examine this question, we generated mice with cell-specific deletion of AT1A receptors from the CD. Elimination of AT1A receptors from both principal and intercalated cells (CDKO mice) had no effect on blood pressures at baseline or during successive feeding of low- or high-salt diets. In contrast, the severity of hypertension caused by chronic infusion of angiotensin II was paradoxically exaggerated in CDKO mice compared with controls. In wild-type mice, angiotensin II induced robust expression of cyclooxygenase-2 (COX-2) in renal medulla, primarily localized to intercalated cells. Upregulation of COX-2 was diminished in CDKO mice, resulting in reduced generation of vasodilator prostanoids. This impaired expression of COX-2 has physiological consequences, since administration of a specific COX-2 inhibitor to CDKO and control mice during angiotensin II infusion equalized their blood pressures. Stimulation of COX-2 was also triggered by exposure of isolated preparations of medullary CDs to angiotensin II. Deletion of AT1A receptors from principal cells alone did not affect angiotensin II-dependent COX2 stimulation, implicating intercalated cells as the main source of COX2 in this setting. These findings suggest a novel paracrine role for the intercalated cell to attenuate the severity of hypertension. Strategies for preserving or augmenting this pathway may have value for improving the management of hypertension.
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Affiliation(s)
- Johannes Stegbauer
- Division of Nephrology, Medical Faculty, University Hospital Düsseldorf, Düsseldorf, Germany.,Division of Nephrology, Department of Medicine, Duke University and Durham VA Medical Centers, Durham, North Carolina, USA
| | - Daian Chen
- Division of Nephrology, Department of Medicine, Duke University and Durham VA Medical Centers, Durham, North Carolina, USA
| | - Marcela Herrera
- Division of Nephrology, Department of Medicine, Duke University and Durham VA Medical Centers, Durham, North Carolina, USA
| | - Matthew A Sparks
- Division of Nephrology, Department of Medicine, Duke University and Durham VA Medical Centers, Durham, North Carolina, USA
| | - Ting Yang
- Division of Nephrology, Department of Medicine, Duke University and Durham VA Medical Centers, Durham, North Carolina, USA
| | - Eva Königshausen
- Division of Nephrology, Medical Faculty, University Hospital Düsseldorf, Düsseldorf, Germany
| | - Susan B Gurley
- Division of Nephrology, Department of Medicine, Duke University and Durham VA Medical Centers, Durham, North Carolina, USA
| | - Thomas M Coffman
- Division of Nephrology, Department of Medicine, Duke University and Durham VA Medical Centers, Durham, North Carolina, USA.,Cardiovascular and Metabolic Disorders Program, Duke-NUS Medical School, Singapore
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36
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Abstract
Treatment and management of kidney disease currently presents an enormous global burden, and the application of nanotechnology principles to renal disease therapy, although still at an early stage, has profound transformative potential. The increasing translation of nanomedicines to the clinic, alongside research efforts in tissue regeneration and organ-on-a-chip investigations, are likely to provide novel solutions to treat kidney diseases. Our understanding of renal anatomy and of how the biological and physico-chemical properties of nanomedicines (the combination of a nanocarrier and a drug) influence their interactions with renal tissues has improved dramatically. Tailoring of nanomedicines in terms of kidney retention and binding to key membranes and cell populations associated with renal diseases is now possible and greatly enhances their localization, tolerability, and efficacy. This Review outlines nanomedicine characteristics central to improved targeting of renal cells and highlights the prospects, challenges, and opportunities of nanotechnology-mediated therapies for renal diseases.
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37
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Soleimani M. Receptor Protein Tyrosine Phosphatase γ, CO2 Sensing in Proximal Tubule and Acid Base Homeostasis. J Am Soc Nephrol 2016; 27:2543-5. [PMID: 27090266 DOI: 10.1681/asn.2016030332] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Affiliation(s)
- Manoocher Soleimani
- Center on Genetics of Transport and Epithelial Biology, Department of Medicine, University of Cincinnati, Cincinnati, Ohio; and Research Services, Veterans Affairs Medical Center, Cincinnati, Ohio
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Atkinson KF, Nauli SM. pH sensors and ion Transporters: Potential therapeutic targets for acid-base disorders. INTERNATIONAL JOURNAL OF PHARMA RESEARCH & REVIEW 2016; 5:51-58. [PMID: 29796385 PMCID: PMC5963282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Regulation of pH is critical for physiological processes. Maintenance of acid-base homeostasis is tightly regulated by the renal and respiratory systems. However, fluctuations in extracellular pH are also sensed by other organ systems. Ion transporter activity to modify the amount of acid (H+ and CO2) and bicarbonate (HCO3-) is therefore actively maintained within the kidney and lung. This review describes acid-base disorders (acidosis and alkalosis) and highlights the importance of pH sensors and ion transporters that may be potential therapeutic targets for treatment of acid-base disorders. Specifically, the renal pH sensors proline-rich tyrosine kinase-2 (Pyk2) and G-protein coupled receptor-4 (GPR4) are discussed here.
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Affiliation(s)
- Kimberly F Atkinson
- Department of Biomedical & Pharmaceutical Sciences, Chapman University, Irvine, CA, USA
| | - Surya M Nauli
- Department of Biomedical & Pharmaceutical Sciences, Chapman University, Irvine, CA, USA
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Zhou Y, Skelton LA, Xu L, Chandler MP, Berthiaume JM, Boron WF. Role of Receptor Protein Tyrosine Phosphatase γ in Sensing Extracellular CO2 and HCO3. J Am Soc Nephrol 2016; 27:2616-21. [PMID: 26839367 DOI: 10.1681/asn.2015040439] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Accepted: 12/17/2015] [Indexed: 01/06/2023] Open
Abstract
Regulation of blood pH-critical for virtually every facet of life-requires that the renal proximal tubule (PT) adjust its rate of H(+) secretion (nearly the same as the rate of HCO3 (-) reabsorption, JHCO3 ) in response to changes in blood [CO2] and [HCO3 (-)]. Yet CO2/HCO3 (-) sensing mechanisms remain poorly characterized. Because receptor tyrosine kinase inhibitors render JHCO3 in the PT insensitive to changes in CO2 concentration, we hypothesized that the structural features of receptor protein tyrosine phosphatase-γ (RPTPγ) that are consistent with binding of extracellular CO2 or HCO3 (-) facilitate monitoring of blood CO2/HCO3 (-) concentrations. We now report that PTs express RPTPγ on blood-facing membranes. Moreover, RPTPγ deletion in mice eliminated the CO2 and HCO3 (-) sensitivities of JHCO3 as well as the normal defense of blood pH during whole-body acidosis. Thus, RPTPγ appears to be a novel extracellular CO2/HCO3 (-) sensor critical for pH homeostasis.
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Affiliation(s)
- Yuehan Zhou
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Lara A Skelton
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Lumei Xu
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Margaret P Chandler
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Jessica M Berthiaume
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Walter F Boron
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, Ohio
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Abstract
Acid-base homeostasis and pH regulation are critical for both normal physiology and cell metabolism and function. The importance of this regulation is evidenced by a variety of physiologic derangements that occur when plasma pH is either high or low. The kidneys have the predominant role in regulating the systemic bicarbonate concentration and hence, the metabolic component of acid-base balance. This function of the kidneys has two components: reabsorption of virtually all of the filtered HCO3(-) and production of new bicarbonate to replace that consumed by normal or pathologic acids. This production or generation of new HCO3(-) is done by net acid excretion. Under normal conditions, approximately one-third to one-half of net acid excretion by the kidneys is in the form of titratable acid. The other one-half to two-thirds is the excretion of ammonium. The capacity to excrete ammonium under conditions of acid loads is quantitatively much greater than the capacity to increase titratable acid. Multiple, often redundant pathways and processes exist to regulate these renal functions. Derangements in acid-base homeostasis, however, are common in clinical medicine and can often be related to the systems involved in acid-base transport in the kidneys.
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Affiliation(s)
- L Lee Hamm
- Department of Medicine, Section of Nephrology, Tulane Hypertension and Renal Center of Excellence, Tulane University School of Medicine, New Orleans, Louisiana; and Medicine Service, Southeast Louisiana Veterans Health Care System, New Orleans, Louisiana
| | - Nazih Nakhoul
- Department of Medicine, Section of Nephrology, Tulane Hypertension and Renal Center of Excellence, Tulane University School of Medicine, New Orleans, Louisiana; and Medicine Service, Southeast Louisiana Veterans Health Care System, New Orleans, Louisiana
| | - Kathleen S Hering-Smith
- Department of Medicine, Section of Nephrology, Tulane Hypertension and Renal Center of Excellence, Tulane University School of Medicine, New Orleans, Louisiana; and Medicine Service, Southeast Louisiana Veterans Health Care System, New Orleans, Louisiana
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Sun X, Stephens L, DuBose TD, Petrovic S. Adaptation by the collecting duct to an exogenous acid load is blunted by deletion of the proton-sensing receptor GPR4. Am J Physiol Renal Physiol 2015; 309:F120-36. [DOI: 10.1152/ajprenal.00507.2014] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Accepted: 05/05/2015] [Indexed: 12/14/2022] Open
Abstract
We previously reported that the deletion of the pH sensor GPR4 causes a non-gap metabolic acidosis and defective net acid excretion (NAE) in the GPR4 knockout mouse (GPR4−/−) (Sun X, Yang LV, Tiegs BC, Arend LJ, McGraw DW, Penn RB, and Petrovic S. J Am Soc Nephrol 21: 1745–1755, 2010). Since the major regulatory site of NAE in the kidney is the collecting duct (CD), we examined acid-base transport proteins in intercalated cells (ICs) of the CD and found comparable mRNA expression of kidney anion exchanger 1 (kAE1), pendrin, and the a4 subunit of H+-ATPase in GPR4−/− vs. +/+. However, NH4Cl loading elicited adaptive doubling of AE1 mRNA in GPR4+/+, but a 50% less pronounced response in GPR4−/−. In GPR4+/+, NH4Cl loading evoked a cellular response characterized by an increase in AE1-labeled and a decrease in pendrin-labeled ICs similar to what was reported in rabbits and rats. This response did not occur in GPR4−/−. Microperfusion experiments demonstrated that the activity of the basolateral Cl−/HCO3− exchanger, kAE1, in CDs isolated from GPR4−/− failed to increase with NH4Cl loading, in contrast to the increase observed in GPR4+/+. Therefore, the deficiency of GPR4 blunted, but did not eliminate the adaptive response to an acid load, suggesting a compensatory response from other pH/CO2/bicarbonate sensors. Indeed, the expression of the calcium-sensing receptor (CaSR) was nearly doubled in GPR4−/− kidneys, in the absence of apparent disturbances of Ca2+ homeostasis. In summary, the expression and activity of the key transport proteins in GPR4−/− mice are consistent with spontaneous metabolic acidosis, but the adaptive response to a superimposed exogenous acid load is blunted and might be partially compensated for by CaSR.
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Affiliation(s)
- Xuming Sun
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, North Carolina
| | - Lisa Stephens
- Department of Internal Medicine, University of Cincinnati, Cincinnati, Ohio
| | - Thomas D. DuBose
- Section on Nephrology, Department of Internal Medicine, Wake Forest School of Medicine, Winston-Salem, North Carolina
| | - Snezana Petrovic
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, North Carolina
- Section on Nephrology, Department of Internal Medicine, Wake Forest School of Medicine, Winston-Salem, North Carolina
- Claude D. Pepper Older Americans Independence Center, Wake Forest School of Medicine, Winston-Salem, North Carolina
- Hypertension and Vascular Research Center, Wake Forest School of Medicine, Winston-Salem, North Carolina; and
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Environmental CO2 inhibits Caenorhabditis elegans egg-laying by modulating olfactory neurons and evokes widespread changes in neural activity. Proc Natl Acad Sci U S A 2015; 112:E3525-34. [PMID: 26100886 DOI: 10.1073/pnas.1423808112] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Carbon dioxide (CO2) gradients are ubiquitous and provide animals with information about their environment, such as the potential presence of prey or predators. The nematode Caenorhabditis elegans avoids elevated CO2, and previous work identified three neuron pairs called "BAG," "AFD," and "ASE" that respond to CO2 stimuli. Using in vivo Ca(2+) imaging and behavioral analysis, we show that C. elegans can detect CO2 independently of these sensory pathways. Many of the C. elegans sensory neurons we examined, including the AWC olfactory neurons, the ASJ and ASK gustatory neurons, and the ASH and ADL nociceptors, respond to a rise in CO2 with a rise in Ca(2+). In contrast, glial sheath cells harboring the sensory endings of C. elegans' major chemosensory neurons exhibit strong and sustained decreases in Ca(2+) in response to high CO2. Some of these CO2 responses appear to be cell intrinsic. Worms therefore may couple detection of CO2 to that of other cues at the earliest stages of sensory processing. We show that C. elegans persistently suppresses oviposition at high CO2. Hermaphrodite-specific neurons (HSNs), the executive neurons driving egg-laying, are tonically inhibited when CO2 is elevated. CO2 modulates the egg-laying system partly through the AWC olfactory neurons: High CO2 tonically activates AWC by a cGMP-dependent mechanism, and AWC output inhibits the HSNs. Our work shows that CO2 is a more complex sensory cue for C. elegans than previously thought, both in terms of behavior and neural circuitry.
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Skelton LA, Boron WF. Effect of acute acid-base disturbances on the phosphorylation of phospholipase C-γ1 and Erk1/2 in the renal proximal tubule. Physiol Rep 2015; 3:e12280. [PMID: 25780091 PMCID: PMC4393148 DOI: 10.14814/phy2.12280] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Revised: 11/20/2014] [Accepted: 11/24/2014] [Indexed: 11/24/2022] Open
Abstract
The renal proximal tubule (PT) plays a major role in whole-body pH homeostasis by secreting H(+) into the tubule lumen. Previous work demonstrated that PTs respond to basolateral changes in [CO2] and [HCO3-] by appropriately altering H(+) secretion-responses blocked by the ErbB inhibitor PD168393, or by eliminating signaling through AT1 angiotensin receptors. In the present study, we analyze phosphorylation of three downstream targets of both ErbBs and AT1: phospholipase C-γ1 (PLC-γ1), extracellular-regulated kinase 1 (Erk1), and Erk2. We expose rabbit PT suspensions for 5 and 20 min to our control (Ctrl) condition (5% CO2, 22 mmol/L HCO3-, pH 7.40) or one of several conditions that mimic acid-base disturbances. We found that each disturbance produces characteristic phosphorylation patterns in the three enzymes. For example, respiratory acidosis (elevated [CO2], normal [HCO3-]) at 20 min decreases PLC-γ1 phosphorylation at tyrosine-783 (relative to Ctrl). Metabolic acidosis (normal [CO2], decreased [HCO3-]) for 5 min increases Erk1 phosphorylation (p-Erk1) but not p-Erk2, whereas metabolic alkalosis (normal [CO2], elevated [HCO3-]) for 5 min decreases p-Erk1 and p-Erk2. In the presence of CO2/HCO3-, PD168393 blocks only two of eight induced decreases in phosphorylation. In two cases in which disturbances have no remarkable effects on phosphorylation, PD168393 unmasks decreases and in two others, increases. These drug effects provide insight into the roles of PD168393-sensitive kinases. Our results indicate that PLC-γ1.pY783, p-Erk1, and p-Erk2 in the PT change in characteristic ways in response to acute acid-base disturbances, and thus presumably contribute to the transduction of acid-base signals.
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Affiliation(s)
- Lara A Skelton
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
| | - Walter F Boron
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
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Affiliation(s)
- Lonny R. Levin
- Department of Pharmacology, Weill Cornell Medical College, New York, NY 10065; ,
| | - Jochen Buck
- Department of Pharmacology, Weill Cornell Medical College, New York, NY 10065; ,
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Renal acid-base regulation: new insights from animal models. Pflugers Arch 2014; 467:1623-41. [PMID: 25515081 DOI: 10.1007/s00424-014-1669-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Revised: 12/02/2014] [Accepted: 12/03/2014] [Indexed: 12/16/2022]
Abstract
Because majority of biological processes are dependent on pH, maintaining systemic acid-base balance is critical. The kidney contributes to systemic acid-base regulation, by reabsorbing HCO3 (-) (both filtered by glomeruli and generated within a nephron) and acidifying urine. Abnormalities in those processes will eventually lead to a disruption in systemic acid-base balance and provoke metabolic acid-base disorders. Research over the past 30 years advanced our understanding on cellular and molecular mechanisms responsible for those processes. In particular, a variety of transgenic animal models, where target genes are deleted either globally or conditionally, provided significant insights into how specific transporters are contributing to the renal acid-base regulation. Here, we broadly overview the mechanisms of renal ion transport participating to acid-base regulation, with emphasis on data obtained from transgenic mice models.
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Yasuoka Y, Sato Y, Healy JM, Nonoguchi H, Kawahara K. pH-sensitive expression of calcium-sensing receptor (CaSR) in type-B intercalated cells of the cortical collecting ducts (CCD) in mouse kidney. Clin Exp Nephrol 2014; 19:771-82. [PMID: 25500736 DOI: 10.1007/s10157-014-1063-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2014] [Accepted: 11/22/2014] [Indexed: 12/18/2022]
Abstract
BACKGROUND The localization and role of the calcium-sensing receptor (CaSR) along the nephron including the collecting ducts is still open to debate. METHODS Using the quantitative, highly sensitive in situ hybridization technique and a double-staining immunohistochemistry technique, we investigated the axial distribution and expression of CaSR along the nephron in mice (C57B/6J) treated for 6 days with acid or alkali diets. RESULTS Under control condition, CaSR was specifically localized in the cortical and medullary thick ascending limb of Henle's loop (CTAL and MTAL), macula densa (MD), distal convoluted tubule (DCT), and CCD (TALs, MD > DCT, CCD). Along the CCD, CaSR was co-localized with an anion exchanger type 4 (AE4), a marker of the basolateral membrane of type-B intercalated cell (IC-B) in mice. On the contrary, CaSR was not detected either in principal cells (PC) or in type-A intercalated cell (IC-A). CaSR expression levels in IC-B significantly (P < 0.005) decreased when mice were fed NH4Cl (acid) diets and increased when animals were given NaHCO3 (alkali) diets. As expected, cell heights of IC-A and IC-B significantly (P < 0.005) increased in the above experimental conditions. Surprisingly, single infusion (ip) of neomycin, an agonist of CaSR, significantly (P < 0.005) increased urinary Ca excretion without further increasing the hourly urine volume and significantly (P < 0.05) decreased urine pH. CONCLUSION CaSR, cloned from rat kidney, was localized in the basolateral membrane of IC-B and was more expressed during alkali-loading. Its alkali-sensitive expression may promote urinary alkali secretion for body acid-base balance.
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Affiliation(s)
- Yukiko Yasuoka
- Department of Physiology, Kitasato University School of Medicine, 1-15-1 Kitasato, Minami-ku, Sagamihara, 252-0374, Japan.,Department of Cellular and Molecular Physiology, Kitasato University Graduate School of Medical Sciences, Sagamihara, 252-0374, Japan
| | - Yuichi Sato
- Department of Molecular Diagnostics, Kitasato University School of Allied Health Sciences, Sagamihara, 252-0374, Japan
| | - Jillian M Healy
- ALESS Program, Komaba Organizational for Educational Excellence, College of Art and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo, 153-8902, Japan
| | - Hiroshi Nonoguchi
- Division of Internal Medicine, Kitasato University Medical Center, 6-100 Arai, Kitamoto, 364-8501, Japan
| | - Katsumasa Kawahara
- Department of Physiology, Kitasato University School of Medicine, 1-15-1 Kitasato, Minami-ku, Sagamihara, 252-0374, Japan. .,Department of Cellular and Molecular Physiology, Kitasato University Graduate School of Medical Sciences, Sagamihara, 252-0374, Japan.
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Tresguerres M, Barott KL, Barron ME, Roa JN. Established and potential physiological roles of bicarbonate-sensing soluble adenylyl cyclase (sAC) in aquatic animals. ACTA ACUST UNITED AC 2014; 217:663-72. [PMID: 24574382 DOI: 10.1242/jeb.086157] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Soluble adenylyl cyclase (sAC) is a recently recognized source of the signaling molecule cyclic AMP (cAMP) that is genetically and biochemically distinct from the classic G-protein-regulated transmembrane adenylyl cyclases (tmACs). Mammalian sAC is distributed throughout the cytoplasm and it may be present in the nucleus and inside mitochondria. sAC activity is directly stimulated by HCO3(-), and sAC has been confirmed to be a HCO3(-) sensor in a variety of mammalian cell types. In addition, sAC can functionally associate with carbonic anhydrases to act as a de facto sensor of pH and CO2. The two catalytic domains of sAC are related to HCO3(-)-regulated adenylyl cyclases from cyanobacteria, suggesting the cAMP pathway is an evolutionarily conserved mechanism for sensing CO2 levels and/or acid/base conditions. Reports of sAC in aquatic animals are still limited but are rapidly accumulating. In shark gills, sAC senses blood alkalosis and triggers compensatory H(+) absorption. In the intestine of bony fishes, sAC modulates NaCl and water absorption. And in sea urchin sperm, sAC may participate in the initiation of flagellar movement and in the acrosome reaction. Bioinformatics and RT-PCR results reveal that sAC orthologs are present in most animal phyla. This review summarizes the current knowledge on the physiological roles of sAC in aquatic animals and suggests additional functions in which sAC may be involved.
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Affiliation(s)
- Martin Tresguerres
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
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Acid-mediated tumor proteolysis: contribution of cysteine cathepsins. Neoplasia 2014; 15:1125-37. [PMID: 24204192 DOI: 10.1593/neo.13946] [Citation(s) in RCA: 84] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2013] [Revised: 08/28/2013] [Accepted: 08/28/2013] [Indexed: 12/21/2022] Open
Abstract
One of the noncellular microenvironmental factors that contribute to malignancy of solid tumors is acidic peritumoral pH. We have previously demonstrated that extracellular acidosis leads to localization of the cysteine pro-tease cathepsin B on the tumor cell membrane and its secretion. The objective of the present study was to determine if an acidic extracellular pH such as that observed in vivo (i.e., pHe 6.8) affects the activity of proteases, e.g., cathepsin B, that contribute to degradation of collagen IV by tumor cells when grown in biologically relevant three-dimensional (3D) cultures. For these studies, we used 1) 3D reconstituted basement membrane overlay cultures of human carcinomas, 2) live cell imaging assays to assess proteolysis, and 3) in vivo imaging of active tumor proteases. At pHe 6.8, there were increases in pericellular active cysteine cathepsins and in degradation of dye-quenched collagen IV, which was partially blocked by a cathepsin B inhibitor. Imaging probes for active cysteine cathepsins localized to tumors in vivo. The amount of bound probe decreased in tumors in bicarbonate-treated mice, a treatment previously shown to increase peritumoral pHe and reduce local invasion of the tumors. Our results are consistent with the acid-mediated invasion hypothesis and with a role for cathepsin B in promoting degradation of a basement membrane protein substrate, i.e., type IV collagen, in an acidic peritumoral environment.
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Dixon J, Lane K, Macphee I, Philips B. Xenobiotic metabolism: the effect of acute kidney injury on non-renal drug clearance and hepatic drug metabolism. Int J Mol Sci 2014; 15:2538-53. [PMID: 24531139 PMCID: PMC3958866 DOI: 10.3390/ijms15022538] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Revised: 12/12/2013] [Accepted: 12/27/2013] [Indexed: 01/20/2023] Open
Abstract
Acute kidney injury (AKI) is a common complication of critical illness, and evidence is emerging that suggests AKI disrupts the function of other organs. It is a recognized phenomenon that patients with chronic kidney disease (CKD) have reduced hepatic metabolism of drugs, via the cytochrome P450 (CYP) enzyme group, and drug dosing guidelines in AKI are often extrapolated from data obtained from patients with CKD. This approach, however, is flawed because several confounding factors exist in AKI. The data from animal studies investigating the effects of AKI on CYP activity are conflicting, although the results of the majority do suggest that AKI impairs hepatic CYP activity. More recently, human study data have also demonstrated decreased CYP activity associated with AKI, in particular the CYP3A subtypes. Furthermore, preliminary data suggest that patients expressing the functional allele variant CYP3A5*1 may be protected from the deleterious effects of AKI when compared with patients homozygous for the variant CYP3A5*3, which codes for a non-functional protein. In conclusion, there is a need to individualize drug prescribing, particularly for the more sick and vulnerable patients, but this needs to be explored in greater depth.
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Affiliation(s)
- John Dixon
- General Intensive Care Unit, St. George's Hospital, London SW17 0QT, UK.
| | - Katie Lane
- General Intensive Care Unit, St. George's Hospital, London SW17 0QT, UK.
| | - Iain Macphee
- Division of Clinical Sciences, St. George's, University of London, London SW17 0RE, UK.
| | - Barbara Philips
- General Intensive Care Unit, St. George's Hospital, London SW17 0QT, UK.
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