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Han X, Akinseye L, Sun Z. KDM6A Demethylase Regulates Renal Sodium Excretion and Blood Pressure. Hypertension 2024; 81:541-551. [PMID: 38164755 PMCID: PMC10922853 DOI: 10.1161/hypertensionaha.123.22026] [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: 09/07/2023] [Accepted: 12/13/2023] [Indexed: 01/03/2024]
Abstract
BACKGROUND KDM6A (Lysine-Specific Demethylase 6A) is a specific demethylase for histone 3 lysine (K) 27 trimethylation (H3K27me3). The purpose of this study is to investigate whether KDM6A in renal tubule cells plays a role in the regulation of kidney function and blood pressure. METHODS We first crossed Ksp-Cre+/- and KDM6Aflox/flox mice for generating inducible kidney-specific deletion of KDM6A gene. RESULTS Notably, conditional knockout of KDM6A gene in renal tubule cells (KDM6A-cKO) increased H3K27me3 levels which leads to a decrease in Na excretion and elevation of blood pressure. Further analysis showed that the expression of NKCC2 (Na-K-2Cl cotransporter 2) and NCC (Na-Cl cotransporters) was upregulated which contributes to impaired Na excretion in KDM6A-cKO mice. The expression of AQP2 (aquaporin 2) was also increased in KDM6A-cKO mice, which may facilitate water reabsorption in KDM6A-cKO mice. The expression of Klotho was downregulated while expression of aging markers including p53, p21, and p16 was upregulated in kidneys of KDM6A-cKO mice, indicating that deletion of KDM6A in the renal tubule cells promotes kidney aging. Interestingly, KDM6A-cKO mice developed salt-sensitive hypertension which can be rescued by treatment with Klotho. KDM6A deficiency induced salt-sensitive hypertension likely through downregulation of the Klotho/ERK (extracellular signal-regulated kinase) signaling and upregulation of the WNK (with-no-lysine kinase) signaling. CONCLUSIONS This study provides the first evidence that KDM6A plays an essential role in maintaining normal tubular function and blood pressure. Renal tubule cell specific KDM6A deficiency causes hypertension due to increased H3K27me3 levels and the resultant downregulation of Klotho gene expression which disrupts the Klotho/ERK/NCC/NKCC2 signaling.
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Affiliation(s)
- Xiaobin Han
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN 38163, USA
| | - Leah Akinseye
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN 38163, USA
| | - Zhongjie Sun
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN 38163, USA
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Marunaka Y. Physiological roles of chloride ions in bodily and cellular functions. J Physiol Sci 2023; 73:31. [PMID: 37968609 PMCID: PMC10717538 DOI: 10.1186/s12576-023-00889-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Accepted: 10/31/2023] [Indexed: 11/17/2023]
Abstract
Physiological roles of Cl-, a major anion in the body, are not well known compared with those of cations. This review article introduces: (1) roles of Cl- in bodily and cellular functions; (2) the range of cytosolic Cl- concentration ([Cl-]c); (3) whether [Cl-]c could change with cell volume change under an isosmotic condition; (4) whether [Cl-]c could change under conditions where multiple Cl- transporters and channels contribute to Cl- influx and efflux in an isosmotic state; (5) whether the change in [Cl-]c could be large enough to act as signals; (6) effects of Cl- on cytoskeletal tubulin polymerization through inhibition of GTPase activity and tubulin polymerization-dependent biological activity; (7) roles of cytosolic Cl- in cell proliferation; (8) Cl--regulatory mechanisms of ciliary motility; (9) roles of Cl- in sweet/umami taste receptors; (10) Cl--regulatory mechanisms of with-no-lysine kinase (WNK); (11) roles of Cl- in regulation of epithelial Na+ transport; (12) relationship between roles of Cl- and H+ in body functions.
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Affiliation(s)
- Yoshinori Marunaka
- Medical Research Institute, Kyoto Industrial Health Association, General Incorporated Foundation, 67 Kitatsuboi-Cho, Nishinokyo, Nakagyo-Ku, Kyoto, 604-8472, Japan.
- Research Organization of Science and Technology, Ritsumeikan University, Kusatsu, 525-8577, Japan.
- Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kamigyo-Ku, Kyoto, 602-8566, Japan.
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3
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Zhou W, Hou Y, Yu T, Wang T, Ding Y, Nie H. Submersion and hypoxia inhibit alveolar epithelial Na + transport through ERK/NF-κB signaling pathway. Respir Res 2023; 24:117. [PMID: 37095538 PMCID: PMC10127099 DOI: 10.1186/s12931-023-02428-z] [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: 10/18/2022] [Accepted: 04/19/2023] [Indexed: 04/26/2023] Open
Abstract
BACKGROUND Hypoxia is associated with many respiratory diseases, partly due to the accumulation of edema fluid and mucus on the surface of alveolar epithelial cell (AEC), which forms oxygen delivery barriers and is responsible for the disruption of ion transport. Epithelial sodium channel (ENaC) on the apical side of AEC plays a crucial role to maintain the electrochemical gradient of Na+ and water reabsorption, thus becomes the key point for edema fluid removal under hypoxia. Here we sought to explore the effects of hypoxia on ENaC expression and the further mechanism related, which may provide a possible treatment strategy in edema related pulmonary diseases. METHODS Excess volume of culture medium was added on the surface of AEC to simulate the hypoxic environment of alveoli in the state of pulmonary edema, supported by the evidence of increased hypoxia-inducible factor-1 expression. The protein/mRNA expressions of ENaC were detected, and extracellular signal-regulated kinase (ERK)/nuclear factor κB (NF-κB) inhibitor was applied to explore the detailed mechanism about the effects of hypoxia on epithelial ion transport in AEC. Meanwhile, mice were placed in chambers with normoxic or hypoxic (8%) condition for 24 h, respectively. The effects of hypoxia and NF-κB were assessed through alveolar fluid clearance and ENaC function by Ussing chamber assay. RESULTS Hypoxia (submersion culture mode) induced the reduction of protein/mRNA expression of ENaC, whereas increased the activation of ERK/NF-κB signaling pathway in parallel experiments using human A549 and mouse alveolar type 2 cells, respectively. Moreover, the inhibition of ERK (PD98059, 10 µM) alleviated the phosphorylation of IκB and p65, implying NF-κB as a downstream pathway involved with ERK regulation. Intriguingly, the expression of α-ENaC could be reversed by either ERK or NF-κB inhibitor (QNZ, 100 nM) under hypoxia. The alleviation of pulmonary edema was evidenced by the administration of NF-κB inhibitor, and enhancement of ENaC function was supported by recording amiloride-sensitive short-circuit currents. CONCLUSIONS The expression of ENaC was downregulated under hypoxia induced by submersion culture, which may be mediated by ERK/NF-κB signaling pathway.
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Affiliation(s)
- Wei Zhou
- Department of Stem Cells and Regenerative Medicine, College of Basic Medical Science, China Medical University, Shenyang, China
| | - Yapeng Hou
- Department of Stem Cells and Regenerative Medicine, College of Basic Medical Science, China Medical University, Shenyang, China
| | - Tong Yu
- Department of Stem Cells and Regenerative Medicine, College of Basic Medical Science, China Medical University, Shenyang, China
| | - Tingyu Wang
- Department of Stem Cells and Regenerative Medicine, College of Basic Medical Science, China Medical University, Shenyang, China
| | - Yan Ding
- Department of Stem Cells and Regenerative Medicine, College of Basic Medical Science, China Medical University, Shenyang, China
| | - Hongguang Nie
- Department of Stem Cells and Regenerative Medicine, College of Basic Medical Science, China Medical University, Shenyang, China.
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Johnston JG, Welch AK, Cain BD, Sayeski PP, Gumz ML, Wingo CS. Aldosterone: Renal Action and Physiological Effects. Compr Physiol 2023; 13:4409-4491. [PMID: 36994769 DOI: 10.1002/cphy.c190043] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/31/2023]
Abstract
Aldosterone exerts profound effects on renal and cardiovascular physiology. In the kidney, aldosterone acts to preserve electrolyte and acid-base balance in response to changes in dietary sodium (Na+ ) or potassium (K+ ) intake. These physiological actions, principally through activation of mineralocorticoid receptors (MRs), have important effects particularly in patients with renal and cardiovascular disease as demonstrated by multiple clinical trials. Multiple factors, be they genetic, humoral, dietary, or otherwise, can play a role in influencing the rate of aldosterone synthesis and secretion from the adrenal cortex. Normally, aldosterone secretion and action respond to dietary Na+ intake. In the kidney, the distal nephron and collecting duct are the main targets of aldosterone and MR action, which stimulates Na+ absorption in part via the epithelial Na+ channel (ENaC), the principal channel responsible for the fine-tuning of Na+ balance. Our understanding of the regulatory factors that allow aldosterone, via multiple signaling pathways, to function properly clearly implicates this hormone as central to many pathophysiological effects that become dysfunctional in disease states. Numerous pathologies that affect blood pressure (BP), electrolyte balance, and overall cardiovascular health are due to abnormal secretion of aldosterone, mutations in MR, ENaC, or effectors and modulators of their action. Study of the mechanisms of these pathologies has allowed researchers and clinicians to create novel dietary and pharmacological targets to improve human health. This article covers the regulation of aldosterone synthesis and secretion, receptors, effector molecules, and signaling pathways that modulate its action in the kidney. We also consider the role of aldosterone in disease and the benefit of mineralocorticoid antagonists. © 2023 American Physiological Society. Compr Physiol 13:4409-4491, 2023.
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Affiliation(s)
- Jermaine G Johnston
- Division of Nephrology, Hypertension and Renal Transplantation, Department of Medicine, University of Florida, Gainesville, Florida, USA
- Department of Physiology and Functional Genomics, University of Florida, Gainesville, Florida, USA
- Nephrology Section, Veteran Administration Medical Center, North Florida/South Georgia Malcom Randall Department of Veterans Affairs Medical Center, Gainesville, Florida, USA
| | - Amanda K Welch
- Division of Nephrology, Hypertension and Renal Transplantation, Department of Medicine, University of Florida, Gainesville, Florida, USA
- Nephrology Section, Veteran Administration Medical Center, North Florida/South Georgia Malcom Randall Department of Veterans Affairs Medical Center, Gainesville, Florida, USA
| | - Brian D Cain
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, Florida, USA
| | - Peter P Sayeski
- Department of Physiology and Functional Genomics, University of Florida, Gainesville, Florida, USA
| | - Michelle L Gumz
- Division of Nephrology, Hypertension and Renal Transplantation, Department of Medicine, University of Florida, Gainesville, Florida, USA
- Department of Physiology and Functional Genomics, University of Florida, Gainesville, Florida, USA
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, Florida, USA
- Nephrology Section, Veteran Administration Medical Center, North Florida/South Georgia Malcom Randall Department of Veterans Affairs Medical Center, Gainesville, Florida, USA
| | - Charles S Wingo
- Division of Nephrology, Hypertension and Renal Transplantation, Department of Medicine, University of Florida, Gainesville, Florida, USA
- Department of Physiology and Functional Genomics, University of Florida, Gainesville, Florida, USA
- Nephrology Section, Veteran Administration Medical Center, North Florida/South Georgia Malcom Randall Department of Veterans Affairs Medical Center, Gainesville, Florida, USA
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Chung YS, Jin HL, Jeong KW. Cell-specific expression of ENACα gene by FOXA1 in the glucocorticoid receptor pathway. Int J Immunopathol Pharmacol 2021; 34:2058738420946192. [PMID: 32838581 PMCID: PMC7450284 DOI: 10.1177/2058738420946192] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Introduction: The glucocorticoid receptor (GR) is one of the most widely studied
ligand-dependent nuclear receptors. The combination of transcriptional
regulatory factors required for the expression of individual genes targeted
by GR varies across cell types; however, the mechanisms underlying this cell
type–specific regulation of gene expression are not yet clear. Methods: Here, we investigated genes regulated by GR in two different cell lines, A549
and ARPE-19, and examined how gene expression varied according to the effect
of pioneer factors using RNA-seq and RT-qPCR. Results: Our RNA-seq results identified 19 and 63 genes regulated by GR that are
ARPE-19-specific and A549-specific, respectively, suggesting that GR induces
the expression of different sets of genes in a cell type–specific manner.
RT-qPCR confirmed that the epithelial sodium channel
(ENACα) gene is an ARPE-19 cell-specific GR target gene,
whereas the FK506 binding protein 5 (FKBP5) gene was A549
cell-specific. There was a significant decrease in ENACα
expression in FOXA1-deficient ARPE-19 cells, suggesting that FOXA1 might
function as a pioneer factor enabling the selective expression of
ENACα in ARPE-19 cells but not in A549 cells. Conclusion: These findings indicate that ENACα expression in ARPE-19
cells is regulated by FOXA1 and provide insights into the molecular
mechanisms of cell type–specific expression of GR-regulated genes.
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Affiliation(s)
- Young Sun Chung
- Gachon Institute of Pharmaceutical Sciences, College of Pharmacy, Gachon University, Incheon, Republic of Korea
| | - Hong Lan Jin
- College of Pharmacy, Yanbian University, Yanji, People's Republic of China
| | - Kwang Won Jeong
- Gachon Institute of Pharmaceutical Sciences, College of Pharmacy, Gachon University, Incheon, Republic of Korea
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Assan F, Vilaine E, Wagner S, Longvert C, Saiag P, Seidowsky A, Bourgault‐Villada I, Massy ZA. Hyponatremia and MAP‐kinase inhibitors in malignant melanoma: Frequency, pathophysiological aspects and clinical consequences. Pigment Cell Melanoma Res 2018; 32:326-331. [PMID: 30387922 DOI: 10.1111/pcmr.12749] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Revised: 09/27/2018] [Accepted: 10/24/2018] [Indexed: 12/12/2022]
Affiliation(s)
- Florence Assan
- Division of Nephrology, Ambroise Paré Hospital APHP Boulogne Billancourt/Paris France
| | - Eve Vilaine
- Division of Nephrology, Ambroise Paré Hospital, APHP Paris‐Ile‐de‐France‐West University (UVSQ) Boulogne Billancourt/Paris France
- INSERM U1018 Team5 Villejuif France
| | | | - Christine Longvert
- Division of Dermatology, Ambroise Paré Hospital, APHP Paris‐Ile‐de‐France‐West University (UVSQ) Boulogne Billancourt/Paris France
| | - Philippe Saiag
- Division of Dermatology, Ambroise Paré Hospital, APHP Paris‐Ile‐de‐France‐West University (UVSQ) Boulogne Billancourt/Paris France
| | - Alexandre Seidowsky
- Division of Nephrology, Ambroise Paré Hospital, APHP Paris‐Ile‐de‐France‐West University (UVSQ) Boulogne Billancourt/Paris France
- INSERM U1018 Team5 Villejuif France
| | - Isabelle Bourgault‐Villada
- Division of Clinical Dermatology‐immunology, Ambroise Paré Hospital, APHP Paris‐Ile‐de‐France‐West University (UVSQ) Boulogne Billancourt/Paris France
| | - Ziad A. Massy
- Division of Nephrology, Ambroise Paré Hospital, APHP Paris‐Ile‐de‐France‐West University (UVSQ) Boulogne Billancourt/Paris France
- INSERM U1018 Team5 Villejuif France
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7
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Stookey JD, Hamer J, Killilea DW. Change in hydration indices associated with an increase in total water intake of more than 0.5 L/day, sustained over 4 weeks, in healthy young men with initial total water intake below 2 L/day. Physiol Rep 2018; 5:5/22/e13356. [PMID: 29150589 PMCID: PMC5704074 DOI: 10.14814/phy2.13356] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Revised: 06/09/2017] [Accepted: 06/23/2017] [Indexed: 01/11/2023] Open
Abstract
This secondary data analysis addressed gaps in knowledge about effects of chronic water intake. Longitudinal data from the Adapt Study were used to describe effects of prescribing a sustained increase in water intake relative to baseline, for 4 weeks, on multiple indices of total body water (TBW) flux, regulation, distribution, and volume in five healthy, free-living, young men, with mean total water intake initially below 2 L/day. Indices were measured weekly. Within-person fixed effect models tested for significant changes in indices over time and associations between changes in indices. Agreement between indices was described. Mixed models tested if baseline between-person differences in hydration indices modified changes in indices over time. Body water flux: The half-life of water in the body decreased significantly. Body water regulation: Serum osmolality decreased significantly. Urine anti-diuretic hormone, sodium, potassium, and osmolality decreased significantly. Plasma aldosterone and serum sodium increased significantly. Body water distribution: No significant changes were observed. Body water volume: Saliva osmolality decreased significantly. Body weight increased significantly by a mean ± SEM of 1.8% ± 0.5% from baseline over 4 weeks. Changes in indices were significantly inter-correlated. Agreement between indices changed over 4 weeks. Baseline saliva osmolality significantly modified responses to chronic water intake. The results motivate hypotheses for future studies: Chronic TBW deficit occurs in healthy individuals under daily life conditions and increases chronic disease risk; Sustained higher water intake restores TBW through gradual isotonic retention of potassium and/or sodium; Saliva osmolality is a sensitive and specific index of chronic hydration status.
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Affiliation(s)
- Jodi D Stookey
- Children's Hospital Oakland Research Institute, Oakland, California
| | - Janice Hamer
- Children's Hospital Oakland Research Institute, Oakland, California
| | - David W Killilea
- Children's Hospital Oakland Research Institute, Oakland, California
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8
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Fujii N, Matsuo Y, Matsunaga T, Endo S, Sakai H, Yamaguchi M, Yamazaki Y, Sugatani J, Ikari A. Hypotonic Stress-induced Down-regulation of Claudin-1 and -2 Mediated by Dephosphorylation and Clathrin-dependent Endocytosis in Renal Tubular Epithelial Cells. J Biol Chem 2016; 291:24787-24799. [PMID: 27733684 DOI: 10.1074/jbc.m116.728196] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2016] [Revised: 09/27/2016] [Indexed: 12/31/2022] Open
Abstract
Hypotonic stress decreased claudin-1 and -2 expression levels in renal tubular epithelial HK-2 and Madin-Darby canine kidney cells. Here, we examined the regulatory mechanism involved in this decrease. The hypotonicity-induced decrease in claudin expression was inhibited by the following: SB202190, a p38 MAPK inhibitor, but not by U0126, a MEK inhibitor; Go6983, a protein kinase C inhibitor; or SP600125, a Jun N-terminal protein kinase inhibitor. Hypotonic stress increased transepithelial electrical resistance, which was inhibited by SB202190. The mRNA expression level of claudin-1 was decreased by hypotonic stress but that of claudin-2 was not. Hypotonic stress decreased the protein stability of claudin-1 and -2. The hypotonicity-induced decrease in claudin expression was inhibited by the following: chloroquine, a lysosome inhibitor; dynasore and monodansylcadaverine, clathrin-dependent endocytosis inhibitors; and siRNA against clathrin heavy chain. Claudin-1 and -2 were mainly distributed in the cytosol and tight junctions (TJs) in the chloroquine- and monodansylcadaverine-treated cells, respectively. Hypotonic stress decreased the phosphorylation levels of claudin-1 and -2, which were inhibited by the protein phosphatase inhibitors okadaic acid and cantharidin. Dephosphorylated mutants of claudin-1 and -2 were mainly distributed in the cytosol, which disappeared in response to hypotonic stress. In contrast, mimicking phosphorylation mutants were distributed in the TJs, which were not decreased by hypotonic stress. We suggest that hypotonic stress induces dephosphorylation, clathrin-dependent endocytosis, and degradation of claudin-1 and -2 in lysosomes, resulting in disruption of the TJ barrier in renal tubular epithelial cells.
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Affiliation(s)
- Naoko Fujii
- From the Laboratory of Biochemistry, Department of Biopharmaceutical Sciences, Gifu Pharmaceutical University, Gifu 501-1196
| | - Yukinobu Matsuo
- From the Laboratory of Biochemistry, Department of Biopharmaceutical Sciences, Gifu Pharmaceutical University, Gifu 501-1196
| | - Toshiyuki Matsunaga
- From the Laboratory of Biochemistry, Department of Biopharmaceutical Sciences, Gifu Pharmaceutical University, Gifu 501-1196
| | - Satoshi Endo
- From the Laboratory of Biochemistry, Department of Biopharmaceutical Sciences, Gifu Pharmaceutical University, Gifu 501-1196
| | - Hideki Sakai
- the Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama 930-0194, and
| | - Masahiko Yamaguchi
- the School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka 422-8526, Japan
| | - Yasuhiro Yamazaki
- the School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka 422-8526, Japan
| | - Junko Sugatani
- the School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka 422-8526, Japan
| | - Akira Ikari
- From the Laboratory of Biochemistry, Department of Biopharmaceutical Sciences, Gifu Pharmaceutical University, Gifu 501-1196,.
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Potential Roles of Amiloride-Sensitive Sodium Channels in Cancer Development. BIOMED RESEARCH INTERNATIONAL 2016; 2016:2190216. [PMID: 27403419 PMCID: PMC4926023 DOI: 10.1155/2016/2190216] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Revised: 04/18/2016] [Accepted: 05/23/2016] [Indexed: 12/15/2022]
Abstract
The ENaC/degenerin ion channel superfamily includes the amiloride-sensitive epithelial sodium channel (ENaC) and acid sensitive ionic channel (ASIC). ENaC is a multimeric ion channel formed by heteromultimeric membrane glycoproteins, which participate in a multitude of biological processes by mediating the transport of sodium (Na+) across epithelial tissues such as the kidney, lungs, bladder, and gut. Aberrant ENaC functions contribute to several human disease states including pseudohypoaldosteronism, Liddle syndrome, cystic fibrosis, and salt-sensitive hypertension. Increasing evidence suggests that ion channels not only regulate ion homeostasis and electric signaling in excitable cells but also play important roles in cancer cell behaviors such as proliferation, apoptosis, invasion, and migration. Indeed, ENaCs/ASICs had been reported to be associated with cancer characteristics. Given their cell surface localization and pharmacology, pharmacological strategies to target ENaC/ASIC family members may be promising cancer therapeutics.
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ENaC Dysregulation Through Activation of MEK1/2 Contributes to Impaired Na+ Absorption in Lymphocytic Colitis. Inflamm Bowel Dis 2016; 22:539-47. [PMID: 26658215 DOI: 10.1097/mib.0000000000000646] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
BACKGROUND Lymphocytic colitis (LC) causes watery diarrhea. We aimed to identify mechanisms of altered Na absorption and regulatory inputs in patients with LC by examining the epithelial Na channel (ENaC) function as the predominant Na transport system in human distal colon. METHODS Epithelial Na channel function and regulation was analyzed in biopsies from sigmoid colon of patients with LC and in rat distal colon in Ussing chambers. ENaC-subunit expression was measured by real-time PCR and RNA sequencing. Correction factors for subepithelial resistance contributions were determined by impedance spectroscopy. Upstream regulators in LC were determined by RNA sequencing. RESULTS Epithelial Na channel-mediated electrogenic Na transport was inhibited despite aldosterone stimulation in human sigmoid colon of patients with LC. The increase in γ-ENaC mRNA expression in response to aldosterone was MEK1/2-dependently reduced in LC, since it could be restored toward normal by MEK1/2 inhibition through U0126. Parallel experiments for identification of signaling in rat distal colon established MEK1/2 to be activated by a cytokine cocktail of TNFα, IFNγ, and IL-15, which were identified as the most important regulators in the upstream regulator analysis in LC. CONCLUSIONS In the sigmoid colon of patients with LC, the key effector cytokines TNFα, IFNγ, and IL-15 inhibited γ-ENaC upregulation in response to aldosterone through a MEK1/2-mediated pathway. This prevents ENaC to reach its maximum transport capacity and results in Na malabsorption which contributes to diarrhea.
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11
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Zhou X. How do kinases contribute to tonicity-dependent regulation of the transcription factor NFAT5? World J Nephrol 2016; 5:20-32. [PMID: 26788461 PMCID: PMC4707165 DOI: 10.5527/wjn.v5.i1.20] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Revised: 10/12/2015] [Accepted: 12/11/2015] [Indexed: 02/06/2023] Open
Abstract
NFAT5 plays a critical role in maintaining the renal functions. Its dis-regulation in the kidney leads to or is associated with certain renal diseases or disorders, most notably the urinary concentration defect. Hypertonicity, which the kidney medulla is normally exposed to, activates NFAT5 through phosphorylation of a signaling molecule or NFAT5 itself. Hypotonicity inhibits NFAT5 through a similar mechanism. More than a dozen of protein and lipid kinases have been identified to contribute to tonicity-dependent regulation of NFAT5. Hypertonicity activates NFAT5 by increasing its nuclear localization and transactivating activity in the early phase and protein abundance in the late phase. The known mechanism for inhibition of NFAT5 by hypotonicity is a decrease of nuclear NFAT5. The present article reviews the effect of each kinase on NFAT5 nuclear localization, transactivation and protein abundance, and the relationship among these kinases, if known. Cyclosporine A and tacrolimus suppress immune reactions by inhibiting the phosphatase calcineurin-dependent activation of NFAT1. It is hoped that this review would stimulate the interest to seek explanations from the NFAT5 regulatory pathways for certain clinical presentations and to explore novel therapeutic approaches based on the pathways. On the basic science front, this review raises two interesting questions. The first one is how these kinases can specifically signal to NFAT5 in the context of hypertonicity or hypotonicity, because they also regulate other cellular activities and even opposite activities in some cases. The second one is why these many kinases, some of which might have redundant functions, are needed to regulate NFAT5 activity. This review reiterates the concept of signaling through cooperation. Cells need these kinases working in a coordinated way to provide the signaling specificity that is lacking in the individual one. Redundancy in regulation of NFAT5 is a critical strategy for cells to maintain robustness against hypertonic or hypotonic stress.
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12
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Feng X, Zhang Y, Shao N, Wang Y, Zhuang Z, Wu P, Lee MJ, Liu Y, Wang X, Zhuang J, Delpire E, Gu D, Cai H. Aldosterone modulates thiazide-sensitive sodium chloride cotransporter abundance via DUSP6-mediated ERK1/2 signaling pathway. Am J Physiol Renal Physiol 2015; 308:F1119-27. [PMID: 25761881 DOI: 10.1152/ajprenal.00543.2014] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Accepted: 03/09/2015] [Indexed: 12/15/2022] Open
Abstract
Thiazide-sensitive sodium chloride cotransporter (NCC) plays an important role in maintaining blood pressure. Aldosterone is known to modulate NCC abundance. Previous studies reported that dietary salts modulated NCC abundance through either WNK4 [with no lysine (k) kinase 4]-SPAK (Ste20-related proline alanine-rich kinase) or WNK4-extracellular signal-regulated kinase-1 and -2 (ERK1/2) signaling pathways. To exclude the influence of SPAK signaling pathway on the role of the aldosterone-mediated ERK1/2 pathway in NCC regulation, we investigated the effects of dietary salt changes and aldosterone on NCC abundance in SPAK knockout (KO) mice. We found that in SPAK KO mice low-salt diet significantly increased total NCC abundance while reducing ERK1/2 phosphorylation, whereas high-salt diet decreased total NCC while increasing ERK1/2 phosphorylation. Importantly, exogenous aldosterone administration increased total NCC abundance in SPAK KO mice while increasing DUSP6 expression, an ERK1/2-specific phosphatase, and led to decreasing ERK1/2 phosphorylation without changing the ratio of phospho-T53-NCC/total NCC. In mouse distal convoluted tubule (mDCT) cells, aldosterone increased DUSP6 expression while reducing ERK1/2 phosphorylation. DUSP6 Knockdown increased ERK1/2 phosphorylation while reducing total NCC expression. Inhibition of DUSP6 by (E)-2-benzylidene-3-(cyclohexylamino)-2,3-dihydro-1H-inden-1-one increased ERK1/2 phosphorylation and reversed the aldosterone-mediated increments of NCC partly by increasing NCC ubiquitination. Therefore, these data suggest that aldosterone modulates NCC abundance via altering NCC ubiquitination through a DUSP6-dependent ERK1/2 signal pathway in SPAK KO mice and part of the effects of dietary salt changes may be mediated by aldosterone in the DCTs.
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Affiliation(s)
- Xiuyan Feng
- Renal Division, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia
| | - Yiqian Zhang
- Renal Division, the Second Affiliated Hospital, Wenzhou Medical University, Zhejiang, China; Renal Division, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia
| | - Ningjun Shao
- Renal Division, the Second Affiliated Hospital, Wenzhou Medical University, Zhejiang, China
| | - Yanhui Wang
- Renal Division, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia; Renal Division, the First Affiliated Hospital, Wenzhou Medical University, Zhejiang, China
| | - Zhizhi Zhuang
- Renal Division, the Second Affiliated Hospital, Wenzhou Medical University, Zhejiang, China; Renal Division, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia
| | - Ping Wu
- Renal Division, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Matthew J Lee
- Renal Division, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia
| | - Yingli Liu
- Renal Division, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia
| | - Xiaonan Wang
- Renal Division, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia
| | - Jieqiu Zhuang
- Renal Division, the Second Affiliated Hospital, Wenzhou Medical University, Zhejiang, China
| | - Eric Delpire
- Department of Anesthesiology, Vanderbilt University School of Medicine, Nashville, Tennessee; and
| | - Dingying Gu
- Renal Division, the Second Affiliated Hospital, Wenzhou Medical University, Zhejiang, China
| | - Hui Cai
- Renal Division, the Second Affiliated Hospital, Wenzhou Medical University, Zhejiang, China; Renal Division, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia; Section of Nephrology, Atlanta Veterans Administration Medical Center, Decatur, Georgia
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13
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Sun H, Niisato N, Inui T, Marunaka Y. Insulin is involved in transcriptional regulation of NKCC and the CFTR Cl(-) channel through PI3K activation and ERK inactivation in renal epithelial cells. J Physiol Sci 2014; 64:433-43. [PMID: 25239597 PMCID: PMC10717268 DOI: 10.1007/s12576-014-0338-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Accepted: 08/31/2014] [Indexed: 01/26/2023]
Abstract
It is is well known that insulin stimulates glucose transport and epithelial Na(+) channel (ENaC)-mediated Na(+) reabsorption; however, the action of insulin on Cl(-) secretion is not fully understood. In this study, we investigated the action of insulin on Na(+)-K(+)-2Cl(-) cotransporter (NKCC)-mediated Cl(-) secretion in epithelial A6 cells. Interestingly, insulin treatment remarkably enhanced the forskolin-stimulated Cl(-) secretion associated with an increase in apical Cl(-) conductance by upregulating mRNA expression of both CFTR and NKCC, although insulin treatment alone had no effect on the basal Cl(-) secretion or apical Cl(-) conductance without forskolin application. We next elucidated a role of phosphoinositide 3-kinase (PI3K) in the insulin-induced enhancement of the Cl(-) secretion, since insulin actually activated PI3K, resulting in activation of Akt, a downstream molecule of PI3K. LY294002 (a PI3K inhibitor) reduced the Cl(-) secretion by suppressing mRNA expression of NKCC, whereas insulin still had a stimulatory action on mRNA expression of CFTR even in the presence of LY294002. On the other hand, we found that a MEK inhibitor (PD98059) further enhanced the insulin-stimulated CFTR mRNA expression and the Cl(-) secretion in forskolin-stimulated A6 cells and that insulin induced slight, transient activation of ERK followed by significant inactivation of ERK. These observations suggest that: (1) insulin respectively upregulates mRNA expression of NKCC and CFTR through activation of PI3K and inactivation of ERK; (2) insulin signals on mRNA expression of NKCC and CFTR are not enough to stimulate transepithelial Cl(-) secretion, but enhance the stimulatory action of cAMP on transepithelial Cl(-) secretion.
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Affiliation(s)
- Hongxin Sun
- Department of Molecular Cell Physiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, 602-8566 Japan
| | - Naomi Niisato
- Department of Molecular Cell Physiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, 602-8566 Japan
- Japan Institute for Food Education and Health, St. Agnes’ University, Kyoto, 602-8013 Japan
| | - Toshio Inui
- Department of Molecular Cell Physiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, 602-8566 Japan
- Department of Bio-Ionomics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, 602-8566 Japan
- Saisei Mirai Clinics, Moriguchi, 570-0012 Japan
| | - Yoshinori Marunaka
- Department of Molecular Cell Physiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, 602-8566 Japan
- Department of Bio-Ionomics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, 602-8566 Japan
- Japan Institute for Food Education and Health, St. Agnes’ University, Kyoto, 602-8013 Japan
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14
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Eaton AF, Yue Q, Eaton DC, Bao HF. ENaC activity and expression is decreased in the lungs of protein kinase C-α knockout mice. Am J Physiol Lung Cell Mol Physiol 2014; 307:L374-85. [PMID: 25015976 DOI: 10.1152/ajplung.00040.2014] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We used a PKC-α knockout model to investigate the regulation of alveolar epithelial Na(+) channels (ENaC) by PKC. Primary alveolar type II (ATII) cells were subjected to cell-attached patch clamp. In the absence of PKC-α, the open probability (Po) of ENaC was decreased by half compared with wild-type mice. The channel density (N) was also reduced in the knockout mice. Using in vivo biotinylation, membrane localization of all three ENaC subunits (α, β, and γ) was decreased in the PKC-α knockout lung, compared with the wild-type. Confocal microscopy of lung slices showed elevated levels of reactive oxygen species (ROS) in the lungs of the PKC-α knockout mice vs. the wild-type. High levels of ROS in the knockout lung can be explained by a decrease in both cytosolic and mitochondrial superoxide dismutase activity. Elevated levels of ROS in the knockout lung activates PKC-δ and leads to reduced dephosphorylation of ERK1/2 by MAP kinase phosphatase, which in turn causes increased internalization of ENaC via ubiquitination by the ubiquitin-ligase Nedd4-2. In addition, in the knockout lung, PKC-δ activates ERK, causing a decrease in ENaC density at the apical alveolar membrane. PKC-δ also phosphorylates MARCKS, leading to a decrease in ENaC Po. The effects of ROS and PKC-δ were confirmed with patch-clamp experiments on isolated ATII cells in which the ROS scavenger, Tempol, or a PKC-δ-specific inhibitor added to patches reversed the observed decrease in ENaC apical channel density and Po. These results explain the decrease in ENaC activity in PKC-α knockout lung.
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Affiliation(s)
- Amity F Eaton
- Department of Physiology and the Center for Cell and Molecular Signaling, Emory University School of Medicine, Atlanta, Georgia
| | - Qiang Yue
- Department of Physiology and the Center for Cell and Molecular Signaling, Emory University School of Medicine, Atlanta, Georgia
| | - Douglas C Eaton
- Department of Physiology and the Center for Cell and Molecular Signaling, Emory University School of Medicine, Atlanta, Georgia
| | - Hui-Fang Bao
- Department of Physiology and the Center for Cell and Molecular Signaling, Emory University School of Medicine, Atlanta, Georgia
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15
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Hosogi S, Kusuzaki K, Inui T, Wang X, Marunaka Y. Cytosolic chloride ion is a key factor in lysosomal acidification and function of autophagy in human gastric cancer cell. J Cell Mol Med 2014; 18:1124-33. [PMID: 24725767 PMCID: PMC4508152 DOI: 10.1111/jcmm.12257] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Accepted: 01/22/2014] [Indexed: 12/21/2022] Open
Abstract
The purpose of the present study was to clarify roles of cytosolic chloride ion (Cl(-) ) in regulation of lysosomal acidification [intra-lysosomal pH (pHlys )] and autophagy function in human gastric cancer cell line (MKN28). The MKN28 cells cultured under a low Cl(-) condition elevated pHlys and reduced the intra-lysosomal Cl(-) concentration ([Cl(-) ]lys ) via reduction of cytosolic Cl(-) concentration ([Cl(-) ]c ), showing abnormal accumulation of LC3II and p62 participating in autophagy function (dysfunction of autophagy) accompanied by inhibition of cell proliferation via G0 /G1 arrest without induction of apoptosis. We also studied effects of direct modification of H(+) transport on lysosomal acidification and autophagy. Application of bafilomycin A1 (an inhibitor of V-type H(+) -ATPase) or ethyl isopropyl amiloride [EIPA; an inhibitor of Na(+) /H(+) exchanger (NHE)] elevated pHlys and decreased [Cl(-) ]lys associated with inhibition of cell proliferation via induction of G0 /G1 arrest similar to the culture under a low Cl(-) condition. However, unlike low Cl(-) condition, application of the compound, bafilomycin A1 or EIPA, induced apoptosis associated with increases in caspase 3 and 9 without large reduction in [Cl(-) ]c compared with low Cl(-) condition. These observations suggest that the lowered [Cl(-) ]c primarily causes dysfunction of autophagy without apoptosis via dysfunction of lysosome induced by disturbance of intra-lysosomal acidification. This is the first study showing that cytosolic Cl(-) is a key factor of lysosome acidification and autophagy.
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Affiliation(s)
- Shigekuni Hosogi
- Department of Molecular Cell Physiology, Graduate School of Medical Science, Kyoto Prefectural University of MedicineKyoto, Japan
- Japan Institute for Food Education and Health, Heian Jogakuin (St. Agnes') UniversityKyoto, Japan
- * Correspondence to: Dr. Shigekuni HOSOGI, M.D., Ph.D. and Prof. Yoshinori MARUNAKA, M.D., Ph.D., Department of Molecular Cell Physiology, Kyoto Prefectural University of Medicine, 465 Kajii-cho, Kamigyo-ku, Kyoto 602-8566, Japan., Tel.: +81-75-251-5311, Fax: +81-75-251-0295, E-mails: for Shigekuni Hosogi; for Yoshinori Marunaka
| | - Katsuyuki Kusuzaki
- Japan Institute for Food Education and Health, Heian Jogakuin (St. Agnes') UniversityKyoto, Japan
- Department of Orthopaedic Surgery, Kyoto Kujo HospitalKyoto, Japan
| | - Toshio Inui
- Department of Molecular Cell Physiology, Graduate School of Medical Science, Kyoto Prefectural University of MedicineKyoto, Japan
- Department of Bio-Ionomics, Graduate School of Medical Science, Kyoto Prefectural University of MedicineKyoto, Japan
- Saisei Mirai ClinicsMoriguchi, Japan
| | - Xiangdong Wang
- Department of Molecular Cell Physiology, Graduate School of Medical Science, Kyoto Prefectural University of MedicineKyoto, Japan
- Department of Respiratory Medicine, Shanghai Respiratory Research Institute, Fudan University Zhongshan HospitalShanghai, China
| | - Yoshinori Marunaka
- Department of Molecular Cell Physiology, Graduate School of Medical Science, Kyoto Prefectural University of MedicineKyoto, Japan
- Japan Institute for Food Education and Health, Heian Jogakuin (St. Agnes') UniversityKyoto, Japan
- Department of Bio-Ionomics, Graduate School of Medical Science, Kyoto Prefectural University of MedicineKyoto, Japan
- Department of Respiratory Medicine, Shanghai Respiratory Research Institute, Fudan University Zhongshan HospitalShanghai, China
- * Correspondence to: Dr. Shigekuni HOSOGI, M.D., Ph.D. and Prof. Yoshinori MARUNAKA, M.D., Ph.D., Department of Molecular Cell Physiology, Kyoto Prefectural University of Medicine, 465 Kajii-cho, Kamigyo-ku, Kyoto 602-8566, Japan., Tel.: +81-75-251-5311, Fax: +81-75-251-0295, E-mails: for Shigekuni Hosogi; for Yoshinori Marunaka
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16
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Wang L, Liu Y, Wang H, Liu X, Chen J, Wang MH, Wang J, Huang H. Epoxyeicosatrienoic acids attenuating hypotonic-induced apoptosis of IMCD cells via γ-ENaC inhibition. PLoS One 2014; 9:e94400. [PMID: 24713619 PMCID: PMC3979856 DOI: 10.1371/journal.pone.0094400] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2014] [Accepted: 03/13/2014] [Indexed: 12/18/2022] Open
Abstract
Inner medulla collecting duct (IMCD) cells are the key part for urinary concentration. Hypotonic stress may trigger apoptosis of IMCD cells and induce renal injury. Epoxyeicosatrienoic acids (EETs) play an important role in anti-apoptosis, but their roles in hypotonic-induced apoptosis of IMCD cells are still unclear. Here we found increasing exogenous 11, 12-EET or endogenous EETs with Ad-CMV-CYP2C23-EGFP transfection decreased apoptosis of IMCD cells induced by hypotonic stress. Moreover, up-regulation of γ-ENaC induced by hypotonic stress was abolished by elevation of exogenous or endogenous EETs. Collectively, this study illustrated that EETs attenuated hypotonic-induced apoptosis of IMCD cells, and that regulation of γ-ENAC may be a possible mechanism contributing to the anti-apoptotic effect of EETs in response to hypotonic stress.
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Affiliation(s)
- Luyun Wang
- Guangdong Province Key Laboratory of Arrhythmia and Electrophysiology, Guangzhou, China
- Department of Critical Care Medicine, Sun Yat-sen Memorial Hospital of Sun Yat-sen University, Guangzhou, China
| | - Yang Liu
- Guangdong Province Key Laboratory of Arrhythmia and Electrophysiology, Guangzhou, China
- Department of Cardiology, Sun Yat-sen Memorial Hospital of Sun Yat-sen University, Guangzhou, China
| | - Huamin Wang
- Zhongshan City Hospital of Chinese Medicine,Affiliated Hospital of Guangzhou University of Chinese Medicine, Zhongshan, China
| | - Xun Liu
- Division of Nephrology, Department of Internal Medicine, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Jie Chen
- Guangdong Province Key Laboratory of Arrhythmia and Electrophysiology, Guangzhou, China
- Radiotherapy Department, Sun Yat-sen Memorial Hospital of Sun Yat-sen University, Guangzhou, China
| | - Mong-Heng Wang
- Department of Physiology, Georgia Regents University, Augusta, Georgia, United States of America
| | - Jingfeng Wang
- Guangdong Province Key Laboratory of Arrhythmia and Electrophysiology, Guangzhou, China
- Department of Cardiology, Sun Yat-sen Memorial Hospital of Sun Yat-sen University, Guangzhou, China
| | - Hui Huang
- Guangdong Province Key Laboratory of Arrhythmia and Electrophysiology, Guangzhou, China
- Department of Cardiology, Sun Yat-sen Memorial Hospital of Sun Yat-sen University, Guangzhou, China
- * E-mail:
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17
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Marunaka Y. Importance of expression and function of angiotensin II receptor type 1 in pulmonary epithelial cells. Respir Physiol Neurobiol 2014; 196:39-42. [PMID: 24594106 DOI: 10.1016/j.resp.2014.02.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Revised: 02/25/2014] [Accepted: 02/25/2014] [Indexed: 11/28/2022]
Affiliation(s)
- Yoshinori Marunaka
- Departments of Molecular Cell Physiology and Bio-Ionomics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto 602-8566, Japan; Japan Institute for Food Education and Health, St. Agnes' University, Kyoto 602-8013, Japan.
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18
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Marunaka Y, Yoshimoto K, Aoi W, Hosogi S, Ikegaya H. Low pH of interstitial fluid around hippocampus of the brain in diabetic OLETF rats. MOLECULAR AND CELLULAR THERAPIES 2014; 2:6. [PMID: 26056575 PMCID: PMC4452057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Accepted: 11/07/2013] [Indexed: 11/21/2023]
Abstract
BACKGROUND We have reported that pH values of ascites and interstitial fluids around the liver in Otsuka Long-Evans Tokushima Fatty (OLETF) rats are significantly lower than normal pH, 7.40, of mammalian body fluids (Biochem Biophys Res Commun 2013, 432:650), and that this lowered pH of interstitial fluid causes the insulin resistance in diabetic patients by decreasing insulin-binding to its receptors (J Physiol Sci 2013, 63:S199). In the preset study, we tried to measure the interstitial fluid pH in diabetic OLETF rats, since the interstitial fluid pH plays key factors in the brain function from a viewpoint of the binding affinity of neurotransmitters to their receptors. FINDINGS We found that the pH value of interstitial fluids around hippocampus, the most important area for memory, in diabetic OLETF rats was lower than that in normal rats by measuring pH with antimony pH electrodes. CONCLUSIONS The lowered pH of interstitial fluid around hippocampus of the brain in diabetic rats observed in the present study suggests that the function of hippocampus of the brain would be diminished due to low affinity of various types of neurotransmitters, playing key roles in the hippocampus function, to their receptors. Therefore, we indicate that maintenance of the interstitial fluid pH at the normal level would be one of the most important key factors for molecular and cellular therapies in various types of diseases including diabetes mellitus.
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Affiliation(s)
- Yoshinori Marunaka
- />Department of Molecular Cell Physiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, 602-8566 Japan
- />Department of Bio-Ionomics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, 602-8566 Japan
- />Japan Institute for Food Education and Health, St. Agnes’ University, Kyoto, 602-8013 Japan
| | - Kanji Yoshimoto
- />Department of Forensic Medicine, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, 602-8566 Japan
- />Departments of Food Sciences and Biotechnology, and Health, Faculty of Life Sciences, Hiroshima Institute of Technology, Hiroshima, 731-5193 Japan
| | - Wataru Aoi
- />Laboratory of Health Science, Graduate School of Life and Environmental Sciences, Kyoto Prefectural University, Kyoto, 606-8522 Japan
| | - Shigekuni Hosogi
- />Department of Molecular Cell Physiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, 602-8566 Japan
- />Japan Institute for Food Education and Health, St. Agnes’ University, Kyoto, 602-8013 Japan
| | - Hiroshi Ikegaya
- />Department of Forensic Medicine, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, 602-8566 Japan
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19
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Marunaka Y, Yoshimoto K, Aoi W, Hosogi S, Ikegaya H. Low pH of interstitial fluid around hippocampus of the brain in diabetic OLETF rats. MOLECULAR AND CELLULAR THERAPIES 2014; 2:6. [PMID: 26056575 PMCID: PMC4452057 DOI: 10.1186/2052-8426-2-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Accepted: 11/07/2013] [Indexed: 02/08/2023]
Abstract
BACKGROUND We have reported that pH values of ascites and interstitial fluids around the liver in Otsuka Long-Evans Tokushima Fatty (OLETF) rats are significantly lower than normal pH, 7.40, of mammalian body fluids (Biochem Biophys Res Commun 2013, 432:650), and that this lowered pH of interstitial fluid causes the insulin resistance in diabetic patients by decreasing insulin-binding to its receptors (J Physiol Sci 2013, 63:S199). In the preset study, we tried to measure the interstitial fluid pH in diabetic OLETF rats, since the interstitial fluid pH plays key factors in the brain function from a viewpoint of the binding affinity of neurotransmitters to their receptors. FINDINGS We found that the pH value of interstitial fluids around hippocampus, the most important area for memory, in diabetic OLETF rats was lower than that in normal rats by measuring pH with antimony pH electrodes. CONCLUSIONS The lowered pH of interstitial fluid around hippocampus of the brain in diabetic rats observed in the present study suggests that the function of hippocampus of the brain would be diminished due to low affinity of various types of neurotransmitters, playing key roles in the hippocampus function, to their receptors. Therefore, we indicate that maintenance of the interstitial fluid pH at the normal level would be one of the most important key factors for molecular and cellular therapies in various types of diseases including diabetes mellitus.
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Affiliation(s)
- Yoshinori Marunaka
- Department of Molecular Cell Physiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, 602-8566 Japan ; Department of Bio-Ionomics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, 602-8566 Japan ; Japan Institute for Food Education and Health, St. Agnes' University, Kyoto, 602-8013 Japan
| | - Kanji Yoshimoto
- Department of Forensic Medicine, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, 602-8566 Japan ; Departments of Food Sciences and Biotechnology, and Health, Faculty of Life Sciences, Hiroshima Institute of Technology, Hiroshima, 731-5193 Japan
| | - Wataru Aoi
- Laboratory of Health Science, Graduate School of Life and Environmental Sciences, Kyoto Prefectural University, Kyoto, 606-8522 Japan
| | - Shigekuni Hosogi
- Department of Molecular Cell Physiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, 602-8566 Japan ; Japan Institute for Food Education and Health, St. Agnes' University, Kyoto, 602-8013 Japan
| | - Hiroshi Ikegaya
- Department of Forensic Medicine, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, 602-8566 Japan
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20
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Marunaka Y. Characteristics and Pharmacological Regulation of Epithelial Na+ Channel (ENaC) and Epithelial Na+ Transport. J Pharmacol Sci 2014. [DOI: 10.1254/jphs.14r01sr] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
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Greenlee MM, Mitzelfelt JD, Yu L, Yue Q, Duke BJ, Harrell CS, Neigh GN, Eaton DC. Estradiol activates epithelial sodium channels in rat alveolar cells through the G protein-coupled estrogen receptor. Am J Physiol Lung Cell Mol Physiol 2013; 305:L878-89. [PMID: 24097558 DOI: 10.1152/ajplung.00008.2013] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Female sex predisposes individuals to poorer outcomes during respiratory disorders like cystic fibrosis and influenza-associated pneumonia. A common link between these disorders is dysregulation of alveolar fluid clearance via disruption of epithelial sodium channel (ENaC) activity. Recent evidence suggests that female sex hormones directly regulate expression and activity of alveolar ENaC. In our study, we identified the mechanism by which estradiol (E2) or progesterone (P4) independently regulates alveolar ENaC. Using cell-attached patch clamp, we measured ENaC single-channel activity in a rat alveolar cell line (L2) in response to overnight exposure to either E2 or P4. In contrast to P4, E2 increased ENaC channel activity (NPo) through an increase in channel open probability (Po) and an increased number of patches with observable channel activity. Apical plasma membrane abundance of the ENaC α-subunit (αENaC) more than doubled in response to E2 as determined by cell surface biotinylation. αENaC membrane abundance was approximately threefold greater in lungs from female rats in proestrus, when serum E2 is greatest, compared with diestrus, when it is lowest. Our results also revealed a significant role for the G protein-coupled estrogen receptor (Gper) to mediate E2's effects on ENaC. Overall, our results demonstrate that E2 signaling through Gper selectively activates alveolar ENaC through an effect on channel gating and channel density, the latter via greater trafficking of channels to the plasma membrane. The results presented herein implicate E2-mediated regulation of alveolar sodium channels in the sex differences observed in the pathogenesis of several pulmonary diseases.
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Affiliation(s)
- Megan M Greenlee
- Dept. of Physiology, Emory Univ. School of Medicine, 615 Michael St., Ste. 655B, Atlanta, GA 30322.
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