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Xiao P, Li C, Liu Y, Gao Y, Liang X, Liu C, Yang W. The role of metal ions in the occurrence, progression, drug resistance, and biological characteristics of gastric cancer. Front Pharmacol 2024; 15:1333543. [PMID: 38370477 PMCID: PMC10869614 DOI: 10.3389/fphar.2024.1333543] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2023] [Accepted: 01/22/2024] [Indexed: 02/20/2024] Open
Abstract
Metal ions exert pivotal functions within the human body, encompassing essential roles in upholding cell structure, gene expression regulation, and catalytic enzyme activity. Additionally, they significantly influence various pathways implicated in divergent mechanisms of cell death. Among the prevailing malignant tumors of the digestive tract worldwide, gastric cancer stands prominent, exhibiting persistent high mortality rates. A compelling body of evidence reveals conspicuous ion irregularities in tumor tissues, encompassing gastric cancer. Notably, metal ions have been observed to elicit distinct contributions to the progression, drug resistance, and biological attributes of gastric cancer. This review consolidates pertinent literature on the involvement of metal ions in the etiology and advancement of gastric cancer. Particular attention is directed towards metal ions, namely, Na, K, Mg, Ca, Fe, Cu, Zn, and Mn, elucidating their roles in the initiation and progression of gastric cancer, cellular demise processes, drug resistance phenomena, and therapeutic approaches.
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Affiliation(s)
- Pengtuo Xiao
- Department of Endoscopy Center, China-Japan Union Hospital of Jilin University, Changchun, China
| | - Changfeng Li
- Department of Endoscopy Center, China-Japan Union Hospital of Jilin University, Changchun, China
| | - Yuanda Liu
- Department of Endoscopy Center, China-Japan Union Hospital of Jilin University, Changchun, China
| | - Yan Gao
- Department of Immunology, College of Basic Medical Sciences, Jilin University, Changchun, China
| | - Xiaojing Liang
- Department of Immunology, College of Basic Medical Sciences, Jilin University, Changchun, China
| | - Chang Liu
- Department of Endoscopy Center, China-Japan Union Hospital of Jilin University, Changchun, China
| | - Wei Yang
- Department of Immunology, College of Basic Medical Sciences, Jilin University, Changchun, China
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2
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Yue Q, Al-Khalili O, Moseley A, Yoshigi M, Wynne BM, Ma H, Eaton DC. PIP 2 Interacts Electrostatically with MARCKS-like Protein-1 and ENaC in Renal Epithelial Cells. BIOLOGY 2022; 11:biology11121694. [PMID: 36552204 PMCID: PMC9774185 DOI: 10.3390/biology11121694] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 09/30/2022] [Accepted: 10/17/2022] [Indexed: 11/25/2022]
Abstract
We examined the interaction of a membrane-associated protein, MARCKS-like Protein-1 (MLP-1), and an ion channel, Epithelial Sodium Channel (ENaC), with the anionic lipid, phosphatidylinositol 4, 5-bisphosphate (PIP2). We found that PIP2 strongly activates ENaC in excised, inside-out patches with a half-activating concentration of 21 ± 1.17 µM. We have identified 2 PIP2 binding sites in the N-terminus of ENaC β and γ with a high concentration of basic residues. Normal channel activity requires MLP-1's strongly positively charged effector domain to electrostatically sequester most of the membrane PIP2 and increase the local concentration of PIP2. Our previous data showed that ENaC covalently binds MLP-1 so PIP2 bound to MLP-1 would be near PIP2 binding sites on the cytosolic N terminal regions of ENaC. We have modified the charge structure of the PIP2 -binding domains of MLP-1 and ENaC and showed that the changes affect membrane localization and ENaC activity in a way consistent with electrostatic theory.
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Affiliation(s)
- Qiang Yue
- Division of Nephrology, Department of Medicine, Emory University, Atlanta, GA 30322, USA
| | - Otor Al-Khalili
- Division of Nephrology, Department of Medicine, Emory University, Atlanta, GA 30322, USA
| | - Auriel Moseley
- Division of Nephrology, Department of Medicine, Emory University, Atlanta, GA 30322, USA
| | - Masaaki Yoshigi
- Division of Nephrology & Hypertension, Department of Internal Medicine, University of Utah, Salt Lake City, UT 84132, USA
| | - Brandi Michele Wynne
- Division of Nephrology & Hypertension, Department of Internal Medicine, University of Utah, Salt Lake City, UT 84132, USA
| | - Heping Ma
- Department of Physiology, Emory University, Atlanta, GA 30322, USA
| | - Douglas C. Eaton
- Division of Nephrology, Department of Medicine, Emory University, Atlanta, GA 30322, USA
- Correspondence: ; Tel.: +1-404-727-4533; Fax: +1-404-727-3425
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3
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Cai YX, Zhang BL, Yu M, Yang YC, Ao X, Zhu D, Wang QS, Lou J, Liang C, Tang LL, Wu MM, Zhang ZR, Ma HP. Cholesterol Stimulates the Transient Receptor Potential Melastatin 4 Channel in mpkCCD c14 Cells. Front Pharmacol 2021; 12:627875. [PMID: 34054517 PMCID: PMC8160378 DOI: 10.3389/fphar.2021.627875] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Accepted: 04/21/2021] [Indexed: 11/24/2022] Open
Abstract
We have shown that cholesterol regulates the activity of ion channels in mouse cortical collecting duct (CCD) mpkCCDc14 cells and that the transient receptor potential melastatin 4 (TRPM4) channel is expressed in these cells. However, whether TRPM4 channel is regulated by cholesterol remains unclear. Here, we performed inside-out patch-clamp experiments and found that inhibition of cholesterol biosynthesis by lovastatin significantly decreased, whereas enrichment of cholesterol with exogenous cholesterol significantly increased, TRPM4 channel open probability (Po) by regulating its sensitivity to Ca2+ in mpkCCDc14 cells. In addition, inside-out patch-clamp data show that acute depletion of cholesterol in the membrane inner leaflet by methyl-β-cyclodextrin (MβCD) significantly reduced TRPM4 Po, which was reversed by exogenous cholesterol. Moreover, immunofluorescence microscopy, Western blot, cell-surface biotinylation, and patch clamp analysis show that neither inhibition of intracellular cholesterol biosynthesis with lovastatin nor application of exogenous cholesterol had effect on TRPM4 channel protein abundance in the plasma membrane of mpkCCDc14 cells. Sucrose density gradient centrifugation studies demonstrate that TRPM4 was mainly located in cholesterol-rich lipid rafts. Lipid-protein overlay experiments show that TRPM4 directly interacted with several anionic phospholipids, including PI(4,5)P2. Depletion of PI(4,5)P2 with either wortmannin or PGE2 abrogated the stimulatory effects of exogenous cholesterol on TRPM4 activity, whereas exogenous PI(4,5)P2 (diC8-PI(4,5)P2, a water-soluble analog) increased the effects. These results suggest that cholesterol stimulates TRPM4 via a PI(4,5)P2-dependent mechanism.
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Affiliation(s)
- Yong-Xu Cai
- Departments of Cardiology and Clinical Pharmacy, Harbin Medical University Cancer Hospital, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Heilongjiang key laboratory for Metabolic disorder and cancer related cardiovascular diseases, and Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and Treatment, Harbin, China
| | - Bao-Long Zhang
- Departments of Cardiology and Clinical Pharmacy, Harbin Medical University Cancer Hospital, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Heilongjiang key laboratory for Metabolic disorder and cancer related cardiovascular diseases, and Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and Treatment, Harbin, China
| | - Miao Yu
- Departments of Cardiology and Clinical Pharmacy, Harbin Medical University Cancer Hospital, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Heilongjiang key laboratory for Metabolic disorder and cancer related cardiovascular diseases, and Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and Treatment, Harbin, China
| | - Yan-Chao Yang
- Departments of Cardiology and Clinical Pharmacy, Harbin Medical University Cancer Hospital, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Heilongjiang key laboratory for Metabolic disorder and cancer related cardiovascular diseases, and Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and Treatment, Harbin, China
| | - Xue Ao
- Departments of Cardiology and Clinical Pharmacy, Harbin Medical University Cancer Hospital, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Heilongjiang key laboratory for Metabolic disorder and cancer related cardiovascular diseases, and Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and Treatment, Harbin, China
| | - Di Zhu
- Departments of Cardiology and Clinical Pharmacy, Harbin Medical University Cancer Hospital, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Heilongjiang key laboratory for Metabolic disorder and cancer related cardiovascular diseases, and Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and Treatment, Harbin, China
| | - Qiu-Shi Wang
- Departments of Cardiology and Clinical Pharmacy, Harbin Medical University Cancer Hospital, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Heilongjiang key laboratory for Metabolic disorder and cancer related cardiovascular diseases, and Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and Treatment, Harbin, China
| | - Jie Lou
- Departments of Cardiology and Clinical Pharmacy, Harbin Medical University Cancer Hospital, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Heilongjiang key laboratory for Metabolic disorder and cancer related cardiovascular diseases, and Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and Treatment, Harbin, China
| | - Chen Liang
- Departments of Cardiology and Clinical Pharmacy, Harbin Medical University Cancer Hospital, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Heilongjiang key laboratory for Metabolic disorder and cancer related cardiovascular diseases, and Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and Treatment, Harbin, China
| | - Liang-Liang Tang
- Departments of Cardiology and Clinical Pharmacy, Harbin Medical University Cancer Hospital, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Heilongjiang key laboratory for Metabolic disorder and cancer related cardiovascular diseases, and Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and Treatment, Harbin, China
| | - Ming-Ming Wu
- Departments of Cardiology and Clinical Pharmacy, Harbin Medical University Cancer Hospital, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Heilongjiang key laboratory for Metabolic disorder and cancer related cardiovascular diseases, and Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and Treatment, Harbin, China
- Department of Physiology, Emory University School of Medicine, Atlanta, GA, United States
| | - Zhi-Ren Zhang
- Departments of Cardiology and Clinical Pharmacy, Harbin Medical University Cancer Hospital, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Heilongjiang key laboratory for Metabolic disorder and cancer related cardiovascular diseases, and Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and Treatment, Harbin, China
- NHC Key Laboratory of Cell Transplantation, Harbin Medical University, Harbin, China
| | - He-Ping Ma
- Department of Physiology, Emory University School of Medicine, Atlanta, GA, United States
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Niu N, Yang X, Zhang BL, Liang C, Zhu D, Wang QS, Cai YX, Yang YC, Ao X, Wu MM, Zhang ZR. Endothelial epithelial sodium channel involves in high-fat diet-induced atherosclerosis in low-density lipoprotein receptor-deficient mice. Biochim Biophys Acta Mol Basis Dis 2020; 1867:165989. [PMID: 33065235 DOI: 10.1016/j.bbadis.2020.165989] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2020] [Revised: 09/05/2020] [Accepted: 10/05/2020] [Indexed: 12/15/2022]
Abstract
We previously showed that increased epithelial sodium channel (ENaC) activity in endothelial cells induced by oxidized low-density lipoprotein (ox-LDL) contributes to vasculature dysfunction. Here, we investigated whether ENaC participates in the pathological process of atherosclerosis using LDL receptor-deficient (LDLr-/-) mice. Male C57BL/6 and LDLr-/- mice were fed a normal diet (ND) or high fat diet (HFD) for 10 weeks. Our data show that treatment of LDLr-/- mice with a specific ENaC blocker, benzamil, significantly decreased atherosclerotic lesion formation and expression of matrix metalloproteinase 2 (MMP2) and metalloproteinase 9 (MMP9) in aortic arteries. Furthermore, benzamil ameliorated HFD-induced impairment of aortic endothelium-dependent dilation by reducing expression of proinflammatory cytokines, including TNF-α, IL-1β, and IL-6 and production of adhesion molecules including VCAM-1 and ICAM-1 in both C57BL/6 and LDLr-/- mice fed with HFD. In addition, HFD significantly increased ENaC activity and the levels of serum lipids, including ox-LDL. Our in vitro data further demonstrated that exogenous ox-LDL significantly increased the production of TNF-α, IL-1β, IL-6, VCAM-1 and ICAM-1. This ox-LDL-induced increase in inflammatory cytokines and adhesion molecules was reversed by γ-ENaC silencing or by treatment with the cyclooxygenase-2 (COX-2) antagonist celecoxib. Benzamil inhibited HFD-induced increase in COX-2 expression in aortic tissue in both C57BL/6 and LDLr-/- mice, and γ-ENaC gene silencing attenuated ox-LDL-induced COX-2 expression in HUVECs. These data together suggest that HFD-induced activation of ENaC stimulates inflammatory signaling, thereby contributes to HFD-induced endothelial dysfunction and atherosclerotic lesion formation. Thus, targeting endothelial ENaC may be a promising strategy to halt atherogenesis.
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Affiliation(s)
- Na Niu
- Departments of Clinical Pharmacy and Cardiology, Harbin Medical University Cancer Hospital, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and Treatment, Harbin, 150081, China
| | - Xu Yang
- Departments of Clinical Pharmacy and Cardiology, Harbin Medical University Cancer Hospital, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and Treatment, Harbin, 150081, China
| | - Bao-Long Zhang
- Departments of Clinical Pharmacy and Cardiology, Harbin Medical University Cancer Hospital, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and Treatment, Harbin, 150081, China
| | - Chen Liang
- Departments of Clinical Pharmacy and Cardiology, Harbin Medical University Cancer Hospital, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and Treatment, Harbin, 150081, China
| | - Di Zhu
- Departments of Clinical Pharmacy and Cardiology, Harbin Medical University Cancer Hospital, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and Treatment, Harbin, 150081, China
| | - Qiu-Shi Wang
- Departments of Clinical Pharmacy and Cardiology, Harbin Medical University Cancer Hospital, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and Treatment, Harbin, 150081, China
| | - Yong-Xu Cai
- Departments of Clinical Pharmacy and Cardiology, Harbin Medical University Cancer Hospital, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and Treatment, Harbin, 150081, China
| | - Yan-Chao Yang
- Departments of Clinical Pharmacy and Cardiology, Harbin Medical University Cancer Hospital, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and Treatment, Harbin, 150081, China
| | - Xue Ao
- Departments of Clinical Pharmacy and Cardiology, Harbin Medical University Cancer Hospital, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and Treatment, Harbin, 150081, China
| | - Ming-Ming Wu
- Departments of Clinical Pharmacy and Cardiology, Harbin Medical University Cancer Hospital, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and Treatment, Harbin, 150081, China
| | - Zhi-Ren Zhang
- Departments of Clinical Pharmacy and Cardiology, Harbin Medical University Cancer Hospital, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and Treatment, Harbin, 150081, China.
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5
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Wu M, Liang C, Yu X, Song B, Yue Q, Zhai Y, Linck V, Cai Y, Niu N, Yang X, Zhang B, Wang Q, Zou L, Zhang S, Thai TL, Ma J, Sutliff RL, Zhang Z, Ma H. Lovastatin attenuates hypertension induced by renal tubule-specific knockout of ATP-binding cassette transporter A1, by inhibiting epithelial sodium channels. Br J Pharmacol 2019; 176:3695-3711. [PMID: 31222723 PMCID: PMC6715779 DOI: 10.1111/bph.14775] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2018] [Revised: 05/12/2019] [Accepted: 06/08/2019] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND AND PURPOSE We have shown that cholesterol is synthesized in the principal cells of renal cortical collecting ducts (CCD) and stimulates the epithelial sodium channels (ENaC). Here we have determined whether lovastatin, a cholesterol synthesis inhibitor, can antagonize the hypertension induced by activated ENaC, following deletion of the cholesterol transporter (ATP-binding cassette transporter A1; ABCA1). EXPERIMENTAL APPROACH We selectively deleted ABCA1 in the principal cells of mouse CCD and used the cell-attached patch-clamp technique to record ENaC activity. Western blot and immunofluorescence staining were used to evaluate protein expression levels. Systolic BP was measured with the tail-cuff method. KEY RESULTS Specific deletion of ABCA1 elevated BP and ENaC single-channel activity in the principal cells of CCD in mice. These effects were antagonized by lovastatin. ABCA1 deletion elevated intracellular cholesterol levels, which was accompanied by elevated ROS, increased expression of serum/glucocorticoid regulated kinase 1 (Sgk1), phosphorylated neural precursor cell-expressed developmentally down-regulated protein 4-2 (Nedd4-2) and furin, along with shorten the primary cilium, and reduced ATP levels in urine. CONCLUSIONS AND IMPLICATIONS These data suggest that specific deletion of ABCA1 in principal cells increases BP by stimulating ENaC channels via a cholesterol-dependent pathway which induces several secondary responses associated with oxidative stress, activated Sgk1/Nedd4-2, increased furin expression, and reduced cilium-mediated release of ATP. As ABCA1 can be blocked by cyclosporine A, these results suggest further investigation of the possible use of statins to treat CsA-induced hypertension.
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Affiliation(s)
- Ming‐Ming Wu
- Departments of Cardiology and Clinic Pharmacy, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and TreatmentHarbin Medical University Cancer HospitalHarbinChina
- Department of PhysiologyEmory University School of MedicineAtlantaGeorgia
| | - Chen Liang
- Departments of Cardiology and Clinic Pharmacy, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and TreatmentHarbin Medical University Cancer HospitalHarbinChina
| | - Xiao‐Di Yu
- Departments of Cardiology and Clinic Pharmacy, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and TreatmentHarbin Medical University Cancer HospitalHarbinChina
| | - Bin‐Lin Song
- Departments of Cardiology and Clinic Pharmacy, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and TreatmentHarbin Medical University Cancer HospitalHarbinChina
- Department of PhysiologyEmory University School of MedicineAtlantaGeorgia
| | - Qiang Yue
- Department of PhysiologyEmory University School of MedicineAtlantaGeorgia
| | - Yu‐Jia Zhai
- Department of PhysiologyEmory University School of MedicineAtlantaGeorgia
| | - Valerie Linck
- Department of PhysiologyEmory University School of MedicineAtlantaGeorgia
| | - Yong‐Xu Cai
- Departments of Cardiology and Clinic Pharmacy, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and TreatmentHarbin Medical University Cancer HospitalHarbinChina
| | - Na Niu
- Departments of Cardiology and Clinic Pharmacy, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and TreatmentHarbin Medical University Cancer HospitalHarbinChina
| | - Xu Yang
- Departments of Cardiology and Clinic Pharmacy, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and TreatmentHarbin Medical University Cancer HospitalHarbinChina
| | - Bao‐Long Zhang
- Departments of Cardiology and Clinic Pharmacy, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and TreatmentHarbin Medical University Cancer HospitalHarbinChina
| | - Qiu‐Shi Wang
- Departments of Cardiology and Clinic Pharmacy, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and TreatmentHarbin Medical University Cancer HospitalHarbinChina
| | - Li Zou
- Department of PhysiologyEmory University School of MedicineAtlantaGeorgia
| | - Shuai Zhang
- Department of PhysiologyEmory University School of MedicineAtlantaGeorgia
| | - Tiffany L. Thai
- Department of PhysiologyEmory University School of MedicineAtlantaGeorgia
| | - Jing Ma
- Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, Department of MedicineAtlanta Veterans Affairs Medical CenterDecaturGeorgia
| | - Roy L. Sutliff
- Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, Department of MedicineAtlanta Veterans Affairs Medical CenterDecaturGeorgia
| | - Zhi‐Ren Zhang
- Departments of Cardiology and Clinic Pharmacy, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and TreatmentHarbin Medical University Cancer HospitalHarbinChina
| | - He‐Ping Ma
- Department of PhysiologyEmory University School of MedicineAtlantaGeorgia
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Zhai YJ, Wu MM, Linck VA, Zou L, Yue Q, Wei SP, Song C, Zhang S, Williams CR, Song BL, Zhang ZR, Ma HP. Intracellular cholesterol stimulates ENaC by interacting with phosphatidylinositol‑4,5‑bisphosphate and mediates cyclosporine A-induced hypertension. Biochim Biophys Acta Mol Basis Dis 2019; 1865:1915-1924. [PMID: 31109455 DOI: 10.1016/j.bbadis.2018.08.027] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Revised: 08/04/2018] [Accepted: 08/19/2018] [Indexed: 12/31/2022]
Abstract
We have previously shown that blockade of ATP-binding cassette transporter A1 (ABCA1) with cyclosporine A (CsA) stimulates the epithelial sodium channel (ENaC) in cultured distal nephron cells. Here we show that CsA elevated systolic blood pressure in both wild-type and apolipoprotein E (ApoE) knockout (KO) mice to a similar level. The elevated systolic blood pressure was completely reversed by inhibition of cholesterol (Cho) synthesis with lovastatin. Inside-out patch-clamp data show that intracellular Cho stimulated ENaC in cultured distal nephron cells by interacting with phosphatidylinositol‑4,5‑bisphosphate (PIP2), an ENaC activator. Confocal microscopy data show that both α‑ENaC and PIP2 were localized in microvilli via a Cho-dependent mechanism. Deletion of membrane Cho reduced the levels of γ‑ENaC in the apical membrane. Reduced ABCA1 expression and elevated intracellular Cho were observed in old mice, compared to young mice. In parallel, cell-attached patch-clamp data from the split-open cortical collecting ducts (CCD) show that ENaC activity was significantly increased in old mice. These data suggest that elevation of intracellular Cho due to blockade of ABCA1 stimulates ENaC, which may contribute to CsA-induced hypertension. This study also implies that reduced ABCA1 expression may mediate age-related hypertension by increasing ENaC activity via elevation of intracellular Cho.
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Affiliation(s)
- Yu-Jia Zhai
- Department of Physiology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Ming-Ming Wu
- Department of Physiology, Emory University School of Medicine, Atlanta, GA 30322, USA; Department of Cardiology, Clinic Pharmacy, Harbin Medical University Cancer Hospital, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and Treatment, Harbin 150081, China
| | - Valerie A Linck
- Department of Physiology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Li Zou
- Department of Physiology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Qiang Yue
- Department of Physiology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Shi-Peng Wei
- Department of Internal Medicine, Medical College of Georgia at Augusta University, Augusta, GA 30912, USA
| | - Chang Song
- Department of Physiology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Shuai Zhang
- Department of Physiology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Clintoria R Williams
- Department of Physiology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Bin-Lin Song
- Department of Physiology, Emory University School of Medicine, Atlanta, GA 30322, USA; Department of Cardiology, Clinic Pharmacy, Harbin Medical University Cancer Hospital, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and Treatment, Harbin 150081, China
| | - Zhi-Ren Zhang
- Department of Cardiology, Clinic Pharmacy, Harbin Medical University Cancer Hospital, Institute of Metabolic Disease, Heilongjiang Academy of Medical Science, Key Laboratories of Education Ministry for Myocardial Ischemia Mechanism and Treatment, Harbin 150081, China.
| | - He-Ping Ma
- Department of Physiology, Emory University School of Medicine, Atlanta, GA 30322, USA.
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7
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Shobair M, Dagliyan O, Kota P, Dang YL, He H, Stutts MJ, Dokholyan NV. Gain-of-Function Mutation W493R in the Epithelial Sodium Channel Allosterically Reconfigures Intersubunit Coupling. J Biol Chem 2015; 291:3682-92. [PMID: 26668308 DOI: 10.1074/jbc.m115.678052] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Indexed: 12/21/2022] Open
Abstract
Sodium absorption in epithelial cells is rate-limited by the epithelial sodium channel (ENaC) activity in lung, kidney, and the distal colon. Pathophysiological conditions, such as cystic fibrosis and Liddle syndrome, result from water-electrolyte imbalance partly due to malfunction of ENaC regulation. Because the quaternary structure of ENaC is yet undetermined, the bases of pathologically linked mutations in ENaC subunits α, β, and γ are largely unknown. Here, we present a structural model of heterotetrameric ENaC α1βα2γ that is consistent with previous cross-linking results and site-directed mutagenesis experiments. By using this model, we show that the disease-causing mutation αW493R rewires structural dynamics of the intersubunit interfaces α1β and α2γ. Changes in dynamics can allosterically propagate to the channel gate. We demonstrate that cleavage of the γ-subunit, which is critical for full channel activation, does not mediate activation of ENaC by αW493R. Our molecular dynamics simulations led us to identify a channel-activating electrostatic interaction between α2Arg-493 and γGlu-348 at the α2γ interface. By neutralizing a sodium-binding acidic patch at the α1β interface, we reduced ENaC activation of αW493R by more than 2-fold. By combining homology modeling, molecular dynamics, cysteine cross-linking, and voltage clamp experiments, we propose a dynamics-driven model for the gain-of-function in ENaC by αW493R. Our integrated computational and experimental approach advances our understanding of structure, dynamics, and function of ENaC in its disease-causing state.
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Affiliation(s)
- Mahmoud Shobair
- From the Program in Molecular and Cellular Biophysics, Curriculum in Bioinformatics and Computational Biology, Department of Biochemistry and Biophysics, and
| | - Onur Dagliyan
- From the Program in Molecular and Cellular Biophysics, Department of Biochemistry and Biophysics, and
| | - Pradeep Kota
- From the Program in Molecular and Cellular Biophysics, Department of Biochemistry and Biophysics, and
| | - Yan L Dang
- Cystic Fibrosis and Pulmonary Diseases Research and Treatment Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Hong He
- Cystic Fibrosis and Pulmonary Diseases Research and Treatment Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - M Jackson Stutts
- Cystic Fibrosis and Pulmonary Diseases Research and Treatment Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Nikolay V Dokholyan
- From the Program in Molecular and Cellular Biophysics, Curriculum in Bioinformatics and Computational Biology, Department of Biochemistry and Biophysics, and Cystic Fibrosis and Pulmonary Diseases Research and Treatment Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
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8
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Liu Y, Flores D, Carrisoza-Gaytán R, Rohatgi R. Cholesterol affects flow-stimulated cyclooxygenase-2 expression and prostanoid secretion in the cortical collecting duct. Am J Physiol Renal Physiol 2015; 308:F1229-37. [PMID: 25761882 DOI: 10.1152/ajprenal.00635.2014] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Accepted: 03/09/2015] [Indexed: 12/31/2022] Open
Abstract
Essential hypertension (eHTN) is associated with hypercholesterolemia, but how cholesterol contributes to eHTN is unknown. Recent evidence demonstrates that short-term dietary cholesterol ingestion induces epithelial Na channel (ENaC)-dependent Na absorption with a subsequent rise in blood pressure (BP), implicating cholesterol in salt-sensitive HTN. Prostaglandin E2 (PGE2), an autocrine/paracrine molecule, is induced by flow in endothelia to vasodilate the vasculature and inhibit ENaC-dependent Na absorption in the renal collecting duct (CD), which reduce BP. We hypothesize that cholesterol suppresses flow-mediated cyclooxygenase-2 (COX-2) expression and PGE2 release in the CD, which, in turn, affects Na absorption. Cortical CDs (CCDs) were microperfused at 0, 1, and 5 nl·min(-1)·mm(-1), and PGE2 release was measured. Secreted PGE2 was similar between no- and low-flow (151 ± 28 vs. 121 ± 48 pg·ml(-1)·mm(-1)) CCDs, but PGE2 was greatest from high-flow (578 ± 146 pg·ml(-1)·mm(-1); P < 0.05) CCDs. Next, mice were fed either a 0 or 1% cholesterol diet, injected with saline to generate high urine flow rates, and CCDs were microdissected for PGE2 secretion. CCDs isolated from cholesterol-fed mice secreted less PGE2 and had a lower PGE2-generating capacity than CCDs isolated from control mice, implying cholesterol repressed flow-induced PGE2 synthesis. Next, cholesterol extraction in a CD cell line induced COX-2 expression and PGE2 release while cholesterol incorporation, conversely, suppressed their expression. Moreover, fluid shear stress (FSS) and cholesterol extraction induced COX-2 protein abundance via p38-dependent activation. Thus cellular cholesterol composition affects biomechanical signaling, which, in turn, affects FSS-mediated COX-2 expression and PGE2 release via a p38-dependent mechanism.
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Affiliation(s)
- Yu Liu
- Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York; Department of Medicine, The James J. Peters Veterans Affairs Medical Center, New York, New York; and
| | - Daniel Flores
- Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York; Department of Medicine, The James J. Peters Veterans Affairs Medical Center, New York, New York; and
| | | | - Rajeev Rohatgi
- Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York; Department of Medicine, The James J. Peters Veterans Affairs Medical Center, New York, New York; and Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York, New York
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9
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Liu BC, Yang LL, Lu XY, Song X, Li XC, Chen G, Li Y, Yao X, Humphrey DR, Eaton DC, Shen BZ, Ma HP. Lovastatin-Induced Phosphatidylinositol-4-Phosphate 5-Kinase Diffusion from Microvilli Stimulates ROMK Channels. J Am Soc Nephrol 2014; 26:1576-87. [PMID: 25349201 DOI: 10.1681/asn.2013121326] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Accepted: 08/25/2014] [Indexed: 12/13/2022] Open
Abstract
We recently showed that lovastatin attenuates cyclosporin A (CsA)-induced damage of cortical collecting duct (CCD) principal cells by reducing intracellular cholesterol. Previous studies showed that, in cell expression models or artificial membranes, exogenous cholesterol directly inhibits inward rectifier potassium channels, including Kir1.1 (Kcnj1; the gene locus for renal outer medullary K(+) [ROMK1] channels). Therefore, we hypothesized that lovastatin might stimulate ROMK1 by reducing cholesterol in CCD cells. Western blots showed that mpkCCDc14 cells express ROMK1 channels with molecular masses that approximate the molecular masses of ROMK1 in renal tubules detected before and after treatment with DTT. Confocal microscopy showed that ROMK1 channels were not in the microvilli, where cholesterol-rich lipid rafts are located, but rather, the planar regions of the apical membrane of mpkCCDc14 cells. Furthermore, phosphatidylinositol-4,5-bisphosphate [PI(4,5)P2], an activator of ROMK channels, was detected mainly in the microvilli under resting conditions along with the kinase responsible for PI(4,5)P2 synthesis, phosphatidylinositol-4-phosphate 5-kinase, type I γ [PI(4)P5K I γ], which may explain the low basal open probability and increased sensitivity to tetraethylammonium observed here for this channel. Notably, lovastatin induced PI(4)P5K I γ diffusion into planar regions and elevated PI(4,5)P2 and ROMK1 open probability in these regions through a cholesterol-associated mechanism. However, exogenous cholesterol alone did not induce these effects. These results suggest that lovastatin stimulates ROMK1 channels, at least in part, by inducing PI(4,5)P2 synthesis in planar regions of the renal CCD cell apical membrane, suggesting that lovastatin could reduce cyclosporin-induced nephropathy and associated hyperkalemia.
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Affiliation(s)
- Bing-Chen Liu
- Departments of Radiology and Cardiology, Fourth Hospital of Harbin Medical University, Harbin, Heilongjiang, China; Department of Physiology and
| | - Li-Li Yang
- Departments of Radiology and Department of Physiology and Molecular Imaging Center, Harbin Medical University, Harbin, Heilongjiang, China; and
| | - Xiao-Yu Lu
- Departments of Radiology and Cardiology, Fourth Hospital of Harbin Medical University, Harbin, Heilongjiang, China; Department of Physiology and
| | - Xiang Song
- Cardiology, Fourth Hospital of Harbin Medical University, Harbin, Heilongjiang, China; Department of Physiology and
| | | | | | - Yichao Li
- Department of Biomedical Engineering, University of Alabama at Birmingham, Birmingham, Alabama
| | - Xincheng Yao
- Department of Biomedical Engineering, University of Alabama at Birmingham, Birmingham, Alabama
| | | | - Douglas C Eaton
- Department of Physiology and Center for Cell and Molecular Signaling, Emory University School of Medicine, Atlanta, Georgia
| | - Bao-Zhong Shen
- Departments of Radiology and Molecular Imaging Center, Harbin Medical University, Harbin, Heilongjiang, China; and
| | - He-Ping Ma
- Department of Physiology and Center for Cell and Molecular Signaling, Emory University School of Medicine, Atlanta, Georgia
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The migratory capacity of human trophoblastic BeWo cells: effects of aldosterone and the epithelial sodium channel. J Membr Biol 2013; 246:243-55. [PMID: 23354843 DOI: 10.1007/s00232-013-9526-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2012] [Accepted: 01/08/2013] [Indexed: 01/08/2023]
Abstract
Aldosterone is a key regulator of the epithelial sodium channel (ENaC) and stimulates protein methylation on the β-subunit of the ENaC. We found that aldosterone (100 nM) promotes cellular migration in a wound-healing model in trophoblastic BeWo cells. Here, we tested if the positive influence of aldosterone on wound healing is related to methylation reactions. Cell migration and proliferation were measured in BeWo cells at 6 h, when mitosis is still scarce. Cell migration covered 12.4, 25.3, 19.6 and 45.1 % of the wound when cultivated under control, aldosterone (12 h), 8Br-cAMP and aldosterone plus 8Br-cAMP, respectively. Amiloride blocked the effects of aldosterone alone or in the presence of 8Br-cAMP on wound healing. Wound healing decreased in aldosterone (plus 8Br-cAMP) coexposed with the methylation inhibitor 3-deaza-adenosine (3-DZA, 12.9 % reinvasion of the wound). There was an increase in wound healing in aldosterone-, 8Br-cAMP- and 3-DZA-treated cells in the presence of AdoMet, a methyl donor, compared to cells in the absence of AdoMet (27.3 and 12.9 % reinvasion of the wound, respectively). Cell proliferation assessed with the reagent MTT was not changed in any of these treatments, suggesting that cellular migration is the main factor for reinvasion of wound healing. Electrophysiological studies showed an increase in ENaC current in the presence of aldosterone. This effect was higher with 8Br-cAMP, and there was a decrease when 3-DZA was present. AdoMet treatment partially reversed this phenomenon. We suggest that aldosterone positively influences wound healing in BeWo cells, at least in part through methylation of the ENaC.
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11
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Rosenhouse‐Dantsker A, Mehta D, Levitan I. Regulation of Ion Channels by Membrane Lipids. Compr Physiol 2012; 2:31-68. [DOI: 10.1002/cphy.c110001] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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Abstract
The epithelial sodium channel (ENaC) is a heteromeric channel composed of three similar but distinct subunits, α, β and γ. This channel is an end-effector in the rennin-angiotensin-aldosterone system and resides in the apical plasma membrane of the renal cortical collecting ducts, where reabsorption of Na(+) through ENaC is the final renal adjustment step for Na(+) balance. Because of its regulation and function, the ENaC plays a critical role in modulating the homeostasis of Na(+) and thus chronic blood pressure. The development of most forms of hypertension requires an increase in Na(+) and water retention. The role of ENaC in developing high blood pressure is exemplified in the gain-of-function mutations in ENaC that cause Liddle's syndrome, a severe but rare form of inheritable hypertension. The evidence obtained from studies using animal models and in human patients indicates that improper Na(+) retention by the kidney elevates blood pressure and induces salt-sensitive hypertension.
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Awayda MS, Awayda KL, Pochynyuk O, Bugaj V, Stockand JD, Ortiz RM. Acute cholesterol-induced anti-natriuretic effects: role of epithelial Na+ channel activity, protein levels, and processing. J Biol Chem 2010; 286:1683-95. [PMID: 21041305 DOI: 10.1074/jbc.m110.159194] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The epithelial Na(+) channel (ENaC) is modulated by membrane lipid composition. However, the effect of an in vivo change of membrane composition is unknown. We examined the effect of a 70-day enhanced cholesterol diet (ECD) on ENaC and renal Na(+) handling. Rats were fed a standard chow or one supplemented with 1% cholesterol and 0.5% cholic acid (ECD). ECD animals exhibited marked anti-diuresis and anti-natriuresis (40 and 47%), which peaked at 1-3 weeks. Secondary compensation returned urine output and urinary Na(+) excretion to control levels by week 10. During these initial changes, there were no accompanying effects on systolic blood pressure, serum creatinine, or urinary creatinine excretion, indicating that the these effects of ECD preceded those which modify renal filtration and blood pressure. The effects of ECD on ENaC were evaluated by measuring the relative protein content of α, β, and γ subunits. α and γ blots were further examined for subunit cleavage (a process that activates ENaC). No significant changes were observed in α and β levels throughout the study. However, levels of cleaved γ were elevated, suggesting that ENaC was activated. The changes of γ persisted at week 10 and were accompanied by additional subunit fragments, indicating potential changes of γ-cleaving proteases. Enhanced protease activity, and specifically that which could act on the second identified cleavage site in γ, was verified in a newly developed urinary protease assay. These results predict enhanced ENaC activity, an effect that was confirmed in patch clamp experiments of principal cells of split open collecting ducts, where ENaC open probability was increased by 40% in the ECD group. These data demonstrate a complex series of events and a new regulatory paradigm that is initiated by ECD prior to the onset of elevated blood pressure. These events lead to changes of renal Na(+) handling, which occur in part by effects on extracellular γ-ENaC cleavage.
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Affiliation(s)
- Mouhamed S Awayda
- Department of Physiology and Biophysics, State University of New York, Buffalo, New York 14214, USA.
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14
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Abstract
A variety of ion channels, including members of all major ion channel families, have been shown to be regulated by changes in the level of membrane cholesterol and partition into cholesterol-rich membrane domains. In general, several types of cholesterol effects have been described. The most common effect is suppression of channel activity by an increase in membrane cholesterol, an effect that was described for several types of inwardly-rectifying K(+) channels, voltage-gated K(+) channels, Ca(+2) sensitive K(+) channels, voltage-gated Na(+) channels, N-type voltage-gated Ca(+2) channels and volume-regulated anion channels. In contrast, several types of ion channels, such as epithelial amiloride-sensitive Na(+) channels and Transient Receptor Potential channels, as well as some of the types of inwardly-rectifying and voltage-gated K(+) channels were shown to be inhibited by cholesterol depletion. Cholesterol was also shown to alter the kinetic properties and current-voltage dependence of several voltage-gated channels. Finally, maintaining membrane cholesterol level is required for coupling ion channels to signalling cascades. In terms of the mechanisms, three general mechanisms have been proposed: (i) specific interactions between cholesterol and the channel protein, (ii) changes in the physical properties of the membrane bilayer and (iii) maintaining the scaffolds for protein-protein interactions. The goal of this review is to describe systematically the role of cholesterol in regulation of the major types of ion channels and to discuss these effects in the context of the models proposed.
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Affiliation(s)
- Irena Levitan
- Department of Medicine, University of Illinois at Chicago, Chicago, IL, USA.
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Del Mónaco SM, Marino GI, Assef YA, Damiano AE, Kotsias BA. Cell migration in BeWo cells and the role of epithelial sodium channels. J Membr Biol 2009; 232:1-13. [PMID: 19911219 DOI: 10.1007/s00232-009-9206-0] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2009] [Accepted: 09/23/2009] [Indexed: 01/08/2023]
Abstract
Cell migration/proliferation processes associated with wound healing were measured in BeWo cells at 6 h, when mitosis is still scarce. Cells were cultured in medium with 1% fetal bovine serum to minimize proliferation. BeWo cell migration covered 20.6 +/- 7.0%, 38.0 +/- 5.4%, 16.6 +/- 4.8% and 13.7 +/- 3.6% of the wound when cultivated under control, aldosterone (100 nM, 12 h), aldosterone plus amiloride (10 muM) and amiloride treatments, respectively. When BeWo cells were treated with aldosterone, there was an increase in wound healing (P < 0.05), which was prevented by adding the ENaC blocker amiloride (P < 0.05, n = 16). Immunocytochemistry studies showed that the three ENaC subunits showed greater expression at the leading edge of the wound 3 h after injury, supporting the notion that these proteins participate in a postinjury signal. Antisense oligonucleotides directed against the alpha-ENaC subunit decreased the migratory response of the cells compared to the sense treated cells or the cells without oligonucleotides (P < 0.001, n = 16): 30.2 +/- 3.7%, 17.6 +/- 1.3%, 27.5 +/- 1.5% and 20.2 +/- 1.5% reinvasion of the wound with aldosterone, aldosterone plus antisense, aldosterone plus sense treatments and control conditions, respectively. Aldosterone and amiloride influence wound healing in BeWo cells, probably by their effects upon ENaCs, transmitting a signal to the cell cytoplasm for the release of several agents that promote cell migration.
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Affiliation(s)
- Silvana M Del Mónaco
- Laboratorio de Canales Iónicos, Instituto de Investigaciones Médicas A. Lanari, Universidad de Buenos Aires, C. de Malvinas 3150, 1427 Buenos Aires, Argentina
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Kopkan L, Khan MAH, Lis A, Awayda MS, Majid DSA. Cholesterol induces renal vasoconstriction and anti-natriuresis by inhibiting nitric oxide production in anesthetized rats. Am J Physiol Renal Physiol 2009; 297:F1606-13. [PMID: 19776170 DOI: 10.1152/ajprenal.90743.2008] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Although hypercholesterolemia is implicated in the pathophysiology of many renal disorders as well as hypertension, its direct actions in the kidney are not yet clearly understood. In the present study, we evaluated renal responses to administration of cholesterol (8 microg x min(-1).100 g body wt(-1); bound by polyethylene glycol) into the renal artery of anesthetized male Sprague-Dawley rats. Total renal blood flow (RBF) was measured by a Transonic flow probe, and glomerular filtration rate (GFR) was determined by Inulin clearance. In control rats (n = 8), cholesterol induced reductions of 10 +/- 2% in RBF [baseline (b) 7.6 +/- 0.3 microg x min(-1).100 g(-1)], 17 +/- 3% in urine flow (b, 10.6 +/- 0.9 microg x min(-1).100 g(-1)), 29 +/- 3% in sodium excretion (b, 0.96 +/- 0.05 mumol.min(-1).100 g(-1)) and 24 +/- 2% in nitrite/nitrate excretion (b, 0.22 +/- 0.01 nmol.min(-1).100 g(-1)) without an appreciable change in GFR (b, 0.87 +/- 0.03 ml.min(-1).100 g(-1)). These renal vasoconstrictor and anti-natriuretic responses to cholesterol were absent in rats pretreated with nitric oxide (NO) synthase inhibitor, nitro-l-arginine methylester (0.5 microg x min(-1).100 g(-1); n = 6). In rats pretreated with superoxide (O(2)(-)) scavenger tempol (50 microg x min(-1).100 g(-1); n = 6), the cholesterol-induced renal responses remained mostly unchanged, although there was a slight attenuation in anti-natriuretic response. This anti-natriuretic response to cholesterol was abolished in furosemide-pretreated rats (0.3 microg x min(-1).100 g(-1); n = 6) but remained unchanged in amiloride-pretreated rats (0.2 microg x min(-1).100 g(-1); n = 5), indicating that Na(+)/K(+)/2Cl(-) cotransport is the dominant mediator of this effect. These data demonstrate that cholesterol-induced acute renal vasoconstrictor and antinatriuretic responses are mediated by a decrease in NO production. These data also indicate that tubular effect of cholesterol on sodium reabsorption is mediated by the furosemide sensitive Na(+)/K(+)/2Cl(-) cotransporter.
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Affiliation(s)
- Libor Kopkan
- Physiology, Hypertension and Renal Center of Excellence, Tulane University Health Sciences Center, New Orleans, Louisiana 70112, USA
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Wang J, Zhang ZR, Chou CF, Liang YY, Gu Y, Ma HP. Cyclosporine stimulates the renal epithelial sodium channel by elevating cholesterol. Am J Physiol Renal Physiol 2008; 296:F284-90. [PMID: 19091785 DOI: 10.1152/ajprenal.90647.2008] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Cyclosporine A (CsA) is an efficient immunosuppressant used for reducing allograft rejection but with a severe side effect of causing hypertension. We hypothesize that the renal epithelial sodium channel (ENaC) may participate in CsA-induced hypertension. In the present study, we used the patch-clamp cell-attached configuration to examine whether and how CsA stimulates ENaC in A6 distal nephron cells. The data showed that CsA significantly increased ENaC open probability. Since CsA is an inhibitor of the ATP-binding cassette A1 (ABCA1) transporter, we employed 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS), another ABCA1 inhibitor, and found that DIDS mimicked the effects of CsA on ENaC basal and cholesterol-induced activity but without any additive effect if combined with CsA. CsA and DIDS also had an identical effect on reduced ENaC activity caused by cholesterol extraction. ABCA1 protein was detected in A6 cells by Western blot analysis. Confocal microscopy data showed that both CsA and DIDS facilitated A6 cells to uptake cholesterol. Since enhanced ENaC activity is known to cause hypertension, these data together suggest that CsA may cause hypertension by stimulating ENaC through a pathway associated with inhibition of ABCA1 and consequent elevation of cholesterol in the cells.
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Affiliation(s)
- Jing Wang
- Division of Nephrology, Univ. of Alabama at Birmingham, 1530 Third Ave. South, Zeigler Research Bldg. 510, Birmingham, AL 35294, USA
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del Mónaco S, Assef Y, Kotsias BA. Epithelial sodium channel in a human trophoblast cell line (BeWo). J Membr Biol 2008; 223:127-39. [PMID: 18665318 DOI: 10.1007/s00232-008-9119-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2008] [Accepted: 07/01/2008] [Indexed: 11/26/2022]
Abstract
The present study was performed to assay sodium currents in BeWo cells. These cells comprise a human trophoblast cell line which displays many of the biochemical and morphological properties similar to those reported for the in uterus proliferative cytotrophoblast. For whole-cell patch-clamp experiments, BeWo cells treated for 12 h with 100 nM aldosterone were exposed to 8Br-cAMP, a membrane-permeable cAMP analogue, to induce channel activity. Cells showed an amiloride-sensitive ion current (IC50 of 5.77 microM). Ion substitution experiments showed that the amiloride-sensitive current carried cations with a permeability rank order of Li+ > Na+ > K+ > NMDG (PLi/PNa = 1.3, PK/PNa = 0.6, PNMDG/PNa = 0.2). In cells pretreated with aldosterone, we observed that nearly half of successful patches had sodium channels with a linear conductance of 6.4 +/- 1.8 pS, a low voltage-independent Po and a PK/PNa of 0.19. Using RT-PCR, we determined that control cells express the alpha-, but not beta- and gamma-, epithelial sodium channel (ENaC) mRNA. When cells were treated with aldosterone (100 nM, 12 h), all alpha-, beta- and gamma-ENaC mRNAs were detected. The presence of ENaC subunit proteins in these cells was confirmed by Western blot analysis and immunolocalization with specific ENaC primary antibodies. In summary, our results suggest that BeWo cells express ENaC subunits and that aldosterone was able to modulate a selective response by generating amiloride-sensitive sodium currents similar to those observed in other human tissues.
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Affiliation(s)
- Silvana del Mónaco
- Laboratorio de Neurofisiología, Instituto de Investigaciones Médicas A. Lanari, University of Buenos Aires, C. de Malvinas 3150, Buenos Aires 1427, Argentina
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