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Feldman RD, Sanjanwala R, Padwal R, Leung AA. Revising the Roles of Aldosterone in Vascular Physiology and Pathophysiology: From Electocortin to Baxdrostat. Can J Cardiol 2023; 39:1808-1815. [PMID: 37734710 DOI: 10.1016/j.cjca.2023.08.035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Revised: 08/29/2023] [Accepted: 08/30/2023] [Indexed: 09/23/2023] Open
Abstract
Aldosterone was initially identified as a hormone primarily related to regulation of fluid and electrolyte homeostasis. However, over the past 20 years there has been an increasing appreciation of its role in regulation of vascular function and pathophysiology in the setting of hypertension, atherosclerosis, and heart failure. This review highlights recent advances in our understanding the biology of aldosterone as it relates to the pathophysiology and the management of vascular disease-especially related to hypertension. The review focuses on 3 key areas: 1) advances in our understanding of the cellular mechanisms by which aldosterone mediates its cellular effects, 2) identification of the hidden epidemic of aldosteronism as a mediator of hypertension, and 3) appreciating new therapeutic advances in the clinical pharmacology of aldosterone inhibition in cardiovascular and renal disease.
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Affiliation(s)
- Ross D Feldman
- Robarts Research Institute, Western University, London, Ontario, Canada.
| | - Rohan Sanjanwala
- Department of Internal Medicine, Max Rady School of Medicine, Winnipeg, Manitoba, Canada
| | - Raj Padwal
- Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Alexander A Leung
- Division of Endocrinology and Metabolism, Department of Medicine, University of Calgary, Calgary, Alberta, Canada
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2
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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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Pearce D, Manis AD, Nesterov V, Korbmacher C. Regulation of distal tubule sodium transport: mechanisms and roles in homeostasis and pathophysiology. Pflugers Arch 2022; 474:869-884. [PMID: 35895103 PMCID: PMC9338908 DOI: 10.1007/s00424-022-02732-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Revised: 07/09/2022] [Accepted: 07/11/2022] [Indexed: 02/03/2023]
Abstract
Regulated Na+ transport in the distal nephron is of fundamental importance to fluid and electrolyte homeostasis. Further upstream, Na+ is the principal driver of secondary active transport of numerous organic and inorganic solutes. In the distal nephron, Na+ continues to play a central role in controlling the body levels and concentrations of a more select group of ions, including K+, Ca++, Mg++, Cl-, and HCO3-, as well as water. Also, of paramount importance are transport mechanisms aimed at controlling the total level of Na+ itself in the body, as well as its concentrations in intracellular and extracellular compartments. Over the last several decades, the transporters involved in moving Na+ in the distal nephron, and directly or indirectly coupling its movement to that of other ions have been identified, and their interrelationships brought into focus. Just as importantly, the signaling systems and their components-kinases, ubiquitin ligases, phosphatases, transcription factors, and others-have also been identified and many of their actions elucidated. This review will touch on selected aspects of ion transport regulation, and its impact on fluid and electrolyte homeostasis. A particular focus will be on emerging evidence for site-specific regulation of the epithelial sodium channel (ENaC) and its role in both Na+ and K+ homeostasis. In this context, the critical regulatory roles of aldosterone, the mineralocorticoid receptor (MR), and the kinases SGK1 and mTORC2 will be highlighted. This includes a discussion of the newly established concept that local K+ concentrations are involved in the reciprocal regulation of Na+-Cl- cotransporter (NCC) and ENaC activity to adjust renal K+ secretion to dietary intake.
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Affiliation(s)
- David Pearce
- Department of Medicine, Division of Nephrology, and Department of Cellular and Molecular Pharmacology, University of California San Francisco, San Francisco, CA USA
| | - Anna D. Manis
- Department of Medicine, Division of Nephrology, and Department of Cellular and Molecular Pharmacology, University of California San Francisco, San Francisco, CA USA
| | - Viatcheslav Nesterov
- Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany, Erlangen, Germany
| | - Christoph Korbmacher
- Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany, Erlangen, Germany
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4
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Tsilosani A, Gao C, Zhang W. Aldosterone-Regulated Sodium Transport and Blood Pressure. Front Physiol 2022; 13:770375. [PMID: 35197862 PMCID: PMC8859437 DOI: 10.3389/fphys.2022.770375] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Accepted: 01/06/2022] [Indexed: 11/13/2022] Open
Abstract
Aldosterone is a major mineralocorticoid steroid hormone secreted by glomerulosa cells in the adrenal cortex. It regulates a variety of physiological responses including those to oxidative stress, inflammation, fluid disruption, and abnormal blood pressure through its actions on various tissues including the kidney, heart, and the central nervous system. Aldosterone synthesis is primarily regulated by angiotensin II, K+ concentration, and adrenocorticotrophic hormone. Elevated serum aldosterone levels increase blood pressure largely by increasing Na+ re-absorption in the kidney through regulating transcription and activity of the epithelial sodium channel (ENaC). This review focuses on the signaling pathways involved in aldosterone synthesis and its effects on Na+ reabsorption through ENaC.
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Affiliation(s)
- Akaki Tsilosani
- Department of Regenerative & Cancer Cell Biology, Albany Medical College, Albany, NY, United States
| | - Chao Gao
- Department of Regenerative & Cancer Cell Biology, Albany Medical College, Albany, NY, United States
| | - Wenzheng Zhang
- Department of Regenerative & Cancer Cell Biology, Albany Medical College, Albany, NY, United States
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Catalogna G, Moraca F, D'Antona L, Dattilo V, Perrotti G, Lupia A, Costa G, Ortuso F, Iuliano R, Trapasso F, Amato R, Alcaro S, Perrotti N. Review about the multi-target profile of resveratrol and its implication in the SGK1 inhibition. Eur J Med Chem 2019; 183:111675. [PMID: 31539779 DOI: 10.1016/j.ejmech.2019.111675] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 08/30/2019] [Accepted: 09/02/2019] [Indexed: 01/08/2023]
Abstract
Resveratrol (trans-3,4',5-trihydroxystilbene) is a polyphenolic natural product with a well-known polypharmacological profile that places it among the multi-target-directed ligands (MTDLs). Given its protective action against a wide number of chronic diseases, in this review, we introduce a general overview about the cardioprotective and antioxidant effects, the antidiabetic, neuroprotective and anti-inflammatory effects of this polyphenol. In the second part of the manuscript, we focused our attention on the anticancer activity of Resveratrol, given the alteration of many different signaling pathways, leading to suppression of tumor cell proliferation in numerous cancer types. Among the several anticancer targets involved in the mechanism of action of Resveratrol, here we introduce experimental and molecular modeling studies performed against the SGK1 protein as a novel anticancer target of Resveratrol. SGK1 inhibitors have been demonstrated to inhibit cell growth of different cancer cells. We demonstrated that resveratrol inhibits SGK1 in vitro and in intact cells, affecting proliferation and survival of HUH7 human hepatoma cells. Our findings demonstrate that resveratrol may function as a SGK1 inhibitor, suggesting possible applications in sodium retention and cancer.
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Affiliation(s)
- Giada Catalogna
- Dipartimento di Medicina Sperimentale e Clinica, University "Magna Græcia" of Catanzaro, Viale Europa, 88100, Catanzaro, Italy
| | - Federica Moraca
- Dipartimento di Scienze Della Salute, University "Magna Græcia" of Catanzaro, Viale Europa, 88100, Catanzaro, Italy; Department of Pharmacy, University of Napoli "Federico II", Via D. Montesano 49, I-80131 Napoli, Italy; Net4Science Srl, Università "Magna Græcia", Campus Salvatore Venuta, Viale Europa, 88100, Catanzaro, Italy
| | - Lucia D'Antona
- Dipartimento di Medicina Sperimentale e Clinica, University "Magna Græcia" of Catanzaro, Viale Europa, 88100, Catanzaro, Italy
| | - Vincenzo Dattilo
- Dipartimento di Medicina Sperimentale e Clinica, University "Magna Græcia" of Catanzaro, Viale Europa, 88100, Catanzaro, Italy
| | - Giuseppe Perrotti
- Dipartimento di Medicina Sperimentale e Clinica, University "Magna Græcia" of Catanzaro, Viale Europa, 88100, Catanzaro, Italy
| | - Antonio Lupia
- Dipartimento di Scienze Della Salute, University "Magna Græcia" of Catanzaro, Viale Europa, 88100, Catanzaro, Italy; Net4Science Srl, Università "Magna Græcia", Campus Salvatore Venuta, Viale Europa, 88100, Catanzaro, Italy
| | - Giosuè Costa
- Dipartimento di Scienze Della Salute, University "Magna Græcia" of Catanzaro, Viale Europa, 88100, Catanzaro, Italy; Net4Science Srl, Università "Magna Græcia", Campus Salvatore Venuta, Viale Europa, 88100, Catanzaro, Italy
| | - Francesco Ortuso
- Dipartimento di Scienze Della Salute, University "Magna Græcia" of Catanzaro, Viale Europa, 88100, Catanzaro, Italy; Net4Science Srl, Università "Magna Græcia", Campus Salvatore Venuta, Viale Europa, 88100, Catanzaro, Italy
| | - Rodolfo Iuliano
- Dipartimento di Medicina Sperimentale e Clinica, University "Magna Græcia" of Catanzaro, Viale Europa, 88100, Catanzaro, Italy
| | - Francesco Trapasso
- Dipartimento di Medicina Sperimentale e Clinica, University "Magna Græcia" of Catanzaro, Viale Europa, 88100, Catanzaro, Italy
| | - Rosario Amato
- Dipartimento di Medicina Sperimentale e Clinica, University "Magna Græcia" of Catanzaro, Viale Europa, 88100, Catanzaro, Italy
| | - Stefano Alcaro
- Dipartimento di Scienze Della Salute, University "Magna Græcia" of Catanzaro, Viale Europa, 88100, Catanzaro, Italy; Net4Science Srl, Università "Magna Græcia", Campus Salvatore Venuta, Viale Europa, 88100, Catanzaro, Italy.
| | - Nicola Perrotti
- Dipartimento di Medicina Sperimentale e Clinica, University "Magna Græcia" of Catanzaro, Viale Europa, 88100, Catanzaro, Italy.
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Swanson EA, Nelson JW, Jeng S, Erspamer KJ, Yang CL, McWeeney S, Ellison DH. Salt-sensitive transcriptome of isolated kidney distal tubule cells. Physiol Genomics 2019; 51:125-135. [PMID: 30875275 DOI: 10.1152/physiolgenomics.00119.2018] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
In the distal kidney tubule, the steroid hormone aldosterone regulates sodium reabsorption via the epithelial sodium channel (ENaC). Most studies seeking to identify ENaC-regulating aldosterone-induced proteins have used transcriptional profiling of cultured cells. To identify salt-sensitive transcripts in an in vivo model, we used low-NaCl or high-NaCl diet to stimulate or suppress endogenous aldosterone, in combination with magnetic- and fluorescence-activated cell sorting to isolate distal tubule cells from mouse kidney for transcriptional profiling. Of the differentially expressed transcripts, 162 were more abundant in distal tubule cells isolated from mice fed low-NaCl diet, and 161 were more abundant in distal tubule cells isolated from mice fed high-NaCl diet. Enrichment analysis of Gene Ontology biological process terms identified multiple statistically overrepresented pathways among the differentially expressed transcripts that were more abundant in distal tubule cells isolated from mice fed low-NaCl diet, including ion transmembrane transport, regulation of growth, and negative regulation of apoptosis. Analysis of Gene Ontology molecular function terms identified differentially expressed transcription factors, transmembrane transporters, kinases, and G protein-coupled receptors. Finally, comparison with a recently published study of gene expression changes in distal tubule cells in response to administration of aldosterone identified 18 differentially expressed genes in common between the two experiments. When expression of these genes was measured in cortical collecting ducts microdissected from mice fed low-NaCl or high-NaCl diet, eight were differentially expressed. These genes are likely to be regulated directly by aldosterone and may provide insight into aldosterone signaling to ENaC in the distal tubule.
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Affiliation(s)
- Elizabeth A Swanson
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health & Science University , Portland, Oregon
| | - Jonathan W Nelson
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health & Science University , Portland, Oregon
| | - Sophia Jeng
- Division of Bioinformatics & Computational Biology, Department of Medical Informatics and Clinical Epidemiology, Oregon Health & Science University , Portland, Oregon
| | - Kayla J Erspamer
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health & Science University , Portland, Oregon
| | - Chao-Ling Yang
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health & Science University , Portland, Oregon
| | - Shannon McWeeney
- Division of Bioinformatics & Computational Biology, Department of Medical Informatics and Clinical Epidemiology, Oregon Health & Science University , Portland, Oregon.,Oregon Clinical & Translational Research Institute, Oregon Health & Science University , Portland, Oregon
| | - David H Ellison
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health & Science University , Portland, Oregon.,Oregon Clinical & Translational Research Institute, Oregon Health & Science University , Portland, Oregon.,Renal Section, Portland VA Medical Center , Portland, Oregon
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7
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Mineralocorticoid receptor: A hidden culprit for hemodialysis vascular access dysfunction. EBioMedicine 2018; 39:621-627. [PMID: 30527626 PMCID: PMC6354623 DOI: 10.1016/j.ebiom.2018.11.054] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 11/25/2018] [Accepted: 11/27/2018] [Indexed: 02/08/2023] Open
Abstract
Hemodialysis vascular access dysfunction is a common and intractable problem in clinical practice with no definitive therapy yet available. As a key mediator of vascular and cardiac maladaptive remodeling, mineralocorticoid receptor (MR) plays a pivotal role in vascular fibrosis and intimal hyperplasia (IH) and is potentiated locally in hemodialysis vascular access following diverse injuries, like barotrauma, cannulation and shear stress. MR-related genomic and non-genomic pathways are responsible for triggering vascular smooth muscle cell activation, proliferation, migration and extracellular matrix overproduction. In endothelial cells, MR signaling diminishes nitric oxide production and its bioavailability, but amplifies reactive oxygen species, leading to an inflammatory state. Moreover, MR favors macrophage polarization towards a pro-inflammatory phenotype. In clinical settings like post-angioplasty or stenting restenosis, the beneficial effect of MR antagonists on vascular fibrosis and IH has been validated. In aggregate, therapeutic targeting of MR may provide a new avenue to prevent hemodialysis vascular access dysfunction. MR signaling is instrumental in both insufficient outward remodeling and exuberant inward remodeling of AVF. The effects of MR in VSMC, endothelial cell, and macrophage act synergistically to promote IH and vascular fibrosis in AVF. Pharmacological targeting of MR represents a novel therapeutic strategy to prevent hemodialysis vascular access dysfunction.
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Hermidorff MM, de Assis LVM, Isoldi MC. Genomic and rapid effects of aldosterone: what we know and do not know thus far. Heart Fail Rev 2018; 22:65-89. [PMID: 27942913 DOI: 10.1007/s10741-016-9591-2] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Aldosterone is the most known mineralocorticoid hormone synthesized by the adrenal cortex. The genomic pathway displayed by aldosterone is attributed to the mineralocorticoid receptor (MR) signaling. Even though the rapid effects displayed by aldosterone are long known, our knowledge regarding the receptor responsible for such event is still poor. It is intense that the debate whether the MR or another receptor-the "unknown receptor"-is the receptor responsible for the rapid effects of aldosterone. Recently, G protein-coupled estrogen receptor-1 (GPER-1) was elegantly shown to mediate some aldosterone-induced rapid effects in several tissues, a fact that strongly places GPER-1 as the unknown receptor. It has also been suggested that angiotensin receptor type 1 (AT1) also participates in the aldosterone-induced rapid effects. Despite this open question, the relevance of the beneficial effects of aldosterone is clear in the kidneys, colon, and CNS as aldosterone controls the important water reabsorption process; on the other hand, detrimental effects displayed by aldosterone have been reported in the cardiovascular system and in the kidneys. In this line, the MR antagonists are well-known drugs that display beneficial effects in patients with heart failure and hypertension; it has been proposed that MR antagonists could also play an important role in vascular disease, obesity, obesity-related hypertension, and metabolic syndrome. Taken altogether, our goal here was to (1) bring a historical perspective of both genomic and rapid effects of aldosterone in several tissues, and the receptors and signaling pathways involved in such processes; and (2) critically address the controversial points within the literature as regarding which receptor participates in the rapid pathway display by aldosterone.
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Affiliation(s)
- Milla Marques Hermidorff
- Laboratory of Hypertension, Research Center in Biological Science, Institute of Exact and Biological Sciences, Federal University of Ouro Preto, Campus Morro do Cruzeiro, Ouro Preto, MG, 35400-000, Brazil
| | - Leonardo Vinícius Monteiro de Assis
- Laboratory of Comparative Physiology of Pigmentation, Department of Physiology, Institute of Biosciences, University of São Paulo, São Paulo, Brazil
| | - Mauro César Isoldi
- Laboratory of Hypertension, Research Center in Biological Science, Institute of Exact and Biological Sciences, Federal University of Ouro Preto, Campus Morro do Cruzeiro, Ouro Preto, MG, 35400-000, Brazil.
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Aguiar SLF, Miranda MCG, Guimarães MAF, Santiago HC, Queiroz CP, Cunha PDS, Cara DC, Foureaux G, Ferreira AJ, Cardoso VN, Barros PA, Maioli TU, Faria AMC. High-Salt Diet Induces IL-17-Dependent Gut Inflammation and Exacerbates Colitis in Mice. Front Immunol 2018; 8:1969. [PMID: 29379505 PMCID: PMC5775230 DOI: 10.3389/fimmu.2017.01969] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Accepted: 12/19/2017] [Indexed: 01/26/2023] Open
Abstract
Excess intake of sodium is often associated with high risk for cardiovascular disease. More recently, some studies on the effects of high-salt diets (HSDs) have also demonstrated that they are able to activate Th17 cells and increase severity of autoimmune diseases. The purpose of the present study was to evaluate the effects of a diet supplemented with NaCl in the colonic mucosa at steady state and during inflammation. We showed that consumption of HSD by mice triggered a gut inflammatory reaction associated with IL-23 production, recruitment of neutrophils, and increased frequency of the IL-17-producing type 3 innate lymphoid cells (ILC3) in the colon. Moreover, gut inflammation was not observed in IL-17–/– mice but it was present, although at lower grade, in RAG−/− mice suggesting that the inflammatory effects of HSD was dependent on IL-17 but only partially on Th17 cells. Expression of SGK1, a kinase involved in sodium homeostasis, increased 90 min after ingestion of 50% NaCl solution and decreased 3 weeks after HSD consumption. Colitis induced by oral administration of either dextran sodium sulfate or 2,4,6-trinitrobenzenesulfonic acid was exacerbated by HSD consumption and this effect was associated with increased frequencies of RORγt+ CD4+ T cells and neutrophils in the colon. Therefore, our results demonstrated that consumption of HSD per se triggered a histologically detectable inflammation in the colon and also exacerbated chemically induced models of colitis in mice by a mechanism dependent on IL-17 production most likely by both ILC3 and Th17 cells.
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Affiliation(s)
- Sarah Leão Fiorini Aguiar
- Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Mariana Camila Gonçalves Miranda
- Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Mauro Andrade Freitas Guimarães
- Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Helton Costa Santiago
- Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Camila Pereira Queiroz
- Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Pricila da Silva Cunha
- Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Denise Carmona Cara
- Departamento de Morfologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Giselle Foureaux
- Departamento de Morfologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Anderson José Ferreira
- Departamento de Morfologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Valbert Nascimento Cardoso
- Departamento de Análises Clínicas e Toxicológicas, Faculdade de Farmácia, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Patrícia Aparecida Barros
- Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Tatiani Uceli Maioli
- Departamento de Nutrição, Escola de Enfermagem, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Ana Maria Caetano Faria
- Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
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Fluid Retention Caused by Rosiglitazone Is Related to Increases in AQP2 and αENaC Membrane Expression. PPAR Res 2017; 2017:8130968. [PMID: 29230238 PMCID: PMC5688369 DOI: 10.1155/2017/8130968] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 08/22/2017] [Accepted: 09/17/2017] [Indexed: 11/17/2022] Open
Abstract
Peroxisome proliferator activated receptor-γ (PPARγ) is a ligand-activated transcription factor of the nuclear hormone receptor superfamily. The decreased phosphorylation of PPARγ due to rosiglitazone (ROS) is the main reason for the increased insulin sensitivity caused by this antidiabetic drug. However, there is no clear evidence whether the nuclear translocation of p-PPARγ stimulated by ROS is related to fluid retention. It is also unclear whether the translocation of p-PPARγ is associated with the change of aquaporin-2 (AQP2) and epithelial sodium channel α subunit (αENaC) in membranes, cytoplasm, and nucleus. Our experiments indicate that ROS significantly downregulates nuclear p-PPARγ and increases membrane AQP2 and αENaC; however, SR1664 (a nonagonist PPARγ ligand) reduces p-PPARγ and has no effect on AQP2 and αENaC. Therefore, we conclude that in vitro the fluid retention caused by ROS is associated with the increases in membrane αENaC and AQP2 but has little relevance to the phosphorylation of PPARγ.
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11
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Nagarajan S, Vohra T, Loffing J, Faresse N. Protein Phosphatase 1α enhances renal aldosterone signaling via mineralocorticoid receptor stabilization. Mol Cell Endocrinol 2017; 450:74-82. [PMID: 28454724 DOI: 10.1016/j.mce.2017.04.020] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Revised: 04/18/2017] [Accepted: 04/22/2017] [Indexed: 01/21/2023]
Abstract
Stimulation of the mineralocorticoid receptor (MR) by aldosterone controls several physiological parameters including blood pressure, inflammation or metabolism. We previously showed that MR turnover constitutes a crucial regulatory step in the responses of renal epithelial cells to aldosterone. Here, we identified Protein Phosphatase 1 alpha (PP1α), as a novel cytoplasmic binding partner of MR that promotes the receptor activity. The RT-PCR expression mapping of PP1α reveals a high expression in the kidney, particularly in the distal part of the nephron. At the molecular level, we demonstrate that PP1α inhibits the ubiquitin ligase Mdm2 by dephosphorylation, preventing its interaction with MR. This results in the accumulation of the receptor due to reduction of its proteasomal degradation and consequently a greater aldosterone-induced Na+ uptake by renal cells. Thus, our findings describe an original mechanism involving a phosphatase in the regulation of aldosterone signaling and provide new and important insights into the molecular mechanism underlying the MR turnover.
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Affiliation(s)
- Shunmugam Nagarajan
- Institute of Anatomy, University of Zurich, 8057 Zurich, Switzerland; National Center of Competence in Research "Kidney.CH", Switzerland
| | - Twinkle Vohra
- Institute of Anatomy, University of Zurich, 8057 Zurich, Switzerland
| | - Johannes Loffing
- Institute of Anatomy, University of Zurich, 8057 Zurich, Switzerland; National Center of Competence in Research "Kidney.CH", Switzerland
| | - Nourdine Faresse
- Institute of Anatomy, University of Zurich, 8057 Zurich, Switzerland; National Center of Competence in Research "Kidney.CH", Switzerland.
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12
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Zhang D, Gu D, He J, Hixson JE, Rao DC, Li C, He H, Chen J, Huang J, Chen J, Rice TK, Chen S, Kelly TN. Associations of the Serum/Glucocorticoid Regulated Kinase Genes With BP Changes and Hypertension Incidence: The Gensalt Study. Am J Hypertens 2017; 30:95-101. [PMID: 27664953 DOI: 10.1093/ajh/hpw122] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Revised: 05/19/2016] [Accepted: 09/08/2016] [Indexed: 01/19/2023] Open
Abstract
BACKGROUND Single-marker and novel gene-based methods were employed to examine the associations of the serum/glucocorticoid regulated kinases (SGK) gene family with longitudinal blood pressure (BP) changes and hypertension incidence in a family-based cohort study. METHODS Totally, 1,768 Chinese participants from the Genetic Epidemiology Network of Salt Sensitivity (GenSalt) follow-up study were included in the current analyses. Nine BP measures were obtained at each of 3 visits during the GenSalt follow-up study. Mixed-model and Gene-based analyses were used to examine the associations of the SGK gene family with longitudinal BP phenotypes. Bonferroni correction was applied to account for multiple testing. RESULTS After an average 7.2-year follow-up, 32.2% (513) of participants free of hypertension at baseline developed hypertension. Four novel SNPs in the SGK1 gene were predictive of the longitudinal BP phenotypes. The major alleles of SGK1 rs1763498 and rs114414980 conferred 2.9- and 2.5-fold increased risks of hypertension development, respectively (P = 1.0×10-4 and 6.0×10-4, respectively). In addition, the major allele of SGK1 rs229133 was significantly associated with 0.4mm Hg larger annual increases in systolic BP (P = 4.2×10-4), while the major allele of rs6924468 was significantly associated with 0.2mm Hg smaller annual increases in diastolic BP (P = 4.2×10-4). Gene-based analyses revealed an association of the SGK1 gene with risk of hypertension development (P = 7.4×10-3). No evidence for the SGK2 and SGK3 genes was found. CONCLUSIONS The findings of the current study suggest that the SGK1 gene may play a role in long-term BP regulation and hypertension incidence.
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Affiliation(s)
- Dingding Zhang
- Department of Evidence Based Medicine, State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center of Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
- Department of Epidemiology, Tulane University School of Public Health and Tropical Medicine, New Orleans, Louisiana, USA
| | - Dongfeng Gu
- Department of Evidence Based Medicine, State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center of Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Jiang He
- Department of Epidemiology, Tulane University School of Public Health and Tropical Medicine, New Orleans, Louisiana, USA
| | - James E Hixson
- Department of Epidemiology, Human Genetics and Environmental Sciences, University of Texas School of Public Health, Houston, Texas, USA
| | - Dabeeru C Rao
- Division of Biostatistics, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Changwei Li
- Department of Epidemiology, Tulane University School of Public Health and Tropical Medicine, New Orleans, Louisiana, USA
| | - Hua He
- Department of Epidemiology, Tulane University School of Public Health and Tropical Medicine, New Orleans, Louisiana, USA
| | - Jichun Chen
- Department of Evidence Based Medicine, State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center of Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Jianfeng Huang
- Department of Evidence Based Medicine, State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center of Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Jing Chen
- Department of Epidemiology, Tulane University School of Public Health and Tropical Medicine, New Orleans, Louisiana, USA
| | - Treva K Rice
- Division of Biostatistics, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Shufeng Chen
- Department of Evidence Based Medicine, State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center of Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Tanika N Kelly
- Department of Epidemiology, Tulane University School of Public Health and Tropical Medicine, New Orleans, Louisiana, USA;
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13
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Proanthocyanidins block aldosterone-dependent up-regulation of cardiac gamma ENaC and Nedd4-2 inactivation via SGK1. J Nutr Biochem 2016; 37:13-19. [PMID: 27592201 DOI: 10.1016/j.jnutbio.2016.07.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Revised: 06/10/2016] [Accepted: 07/15/2016] [Indexed: 11/21/2022]
Abstract
Aldosterone plays a central role in the development of cardiac pathological states involving ion transport imbalances, especially sodium transport. We have previously demonstrated a cardioprotective effect of proanthocyanidins in aldosterone-treated rats. Our objective was to investigate for the first time the effect of proanthocyanidins on serum and glucocorticoid-regulated kinase 1 (SGK1), epithelial Na+ channel (γ-ENaC), neuronal precursor cells expressed developmentally down-regulated 4-2 (Nedd4-2) and phosphoNedd4-2 protein expression in the hearts of aldosterone-treated rats. Male Wistar rats received aldosterone (1mg kg-1day-1)+1% NaCl for 3weeks. Half of the animals in each group were simultaneously treated with the proanthocyanidins-rich extract (80% w/w) (PRO80, 5mg kg-1day-1). Hypertension and diastolic dysfunction induced by aldosterone were abolished by treatment with PRO80. Expression of fibrotic, inflammatory and oxidative mediators were increased by aldosterone-salt administration and blunted by PRO80. Antioxidant capacity was improved by PRO80. The up-regulated aldosterone mediator SGK1, ENaC and p-Nedd4-2/total Nedd4-2 ratio were blocked by PRO80. PRO80 blunted aldosterone-mineralocorticoid-mediated up-regulation of ENaC provides new mechanistic insight of the beneficial effect of proanthocyanidins preventing the cardiac alterations induced by aldosterone excess.
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14
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Lou Y, Zhang F, Luo Y, Wang L, Huang S, Jin F. Serum and Glucocorticoid Regulated Kinase 1 in Sodium Homeostasis. Int J Mol Sci 2016; 17:ijms17081307. [PMID: 27517916 PMCID: PMC5000704 DOI: 10.3390/ijms17081307] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Revised: 08/02/2016] [Accepted: 08/03/2016] [Indexed: 12/13/2022] Open
Abstract
The ubiquitously expressed serum and glucocorticoid regulated kinase 1 (SGK1) is tightly regulated by osmotic and hormonal signals, including glucocorticoids and mineralocorticoids. Recently, SGK1 has been implicated as a signal hub for the regulation of sodium transport. SGK1 modulates the activities of multiple ion channels and carriers, such as epithelial sodium channel (ENaC), voltage-gated sodium channel (Nav1.5), sodium hydrogen exchangers 1 and 3 (NHE1 and NHE3), sodium-chloride symporter (NCC), and sodium-potassium-chloride cotransporter 2 (NKCC2); as well as the sodium-potassium adenosine triphosphatase (Na+/K+-ATPase) and type A natriuretic peptide receptor (NPR-A). Accordingly, SGK1 is implicated in the physiology and pathophysiology of Na+ homeostasis. Here, we focus particularly on recent findings of SGK1’s involvement in Na+ transport in renal sodium reabsorption, hormone-stimulated salt appetite and fluid balance and discuss the abnormal SGK1-mediated Na+ reabsorption in hypertension, heart disease, edema with diabetes, and embryo implantation failure.
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Affiliation(s)
- Yiyun Lou
- Department of Reproductive Endocrinology, Women's Hospital, School of Medicine, Zhejiang University, Hangzhou 310006, Zhejiang, China.
- Department of Gynaecology, Hangzhou Hospital of Traditional Chinese Medicine, Hangzhou 310007, Zhejiang, China.
| | - Fan Zhang
- Department of Reproductive Endocrinology, Women's Hospital, School of Medicine, Zhejiang University, Hangzhou 310006, Zhejiang, China.
| | - Yuqin Luo
- Department of Reproductive Endocrinology, Women's Hospital, School of Medicine, Zhejiang University, Hangzhou 310006, Zhejiang, China.
| | - Liya Wang
- Department of Reproductive Endocrinology, Women's Hospital, School of Medicine, Zhejiang University, Hangzhou 310006, Zhejiang, China.
| | - Shisi Huang
- Department of Reproductive Endocrinology, Women's Hospital, School of Medicine, Zhejiang University, Hangzhou 310006, Zhejiang, China.
| | - Fan Jin
- Department of Reproductive Endocrinology, Women's Hospital, School of Medicine, Zhejiang University, Hangzhou 310006, Zhejiang, China.
- Key Laboratory of Reproductive Genetics, National Ministry of Education (Zhejiang University), Women's Reproductive Healthy Laboratory of Zhejiang Province, Hangzhou 310058, Zhejiang, China.
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15
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Cattaneo A, Riva MA. Stress-induced mechanisms in mental illness: A role for glucocorticoid signalling. J Steroid Biochem Mol Biol 2016; 160:169-74. [PMID: 26241031 DOI: 10.1016/j.jsbmb.2015.07.021] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Revised: 07/28/2015] [Accepted: 07/30/2015] [Indexed: 10/23/2022]
Abstract
Stress represents the main environmental risk factor for mental illness. Exposure to stressful events, particularly early in life, has been associated with increased incidence and susceptibility of major depressive disorders as well as of other psychiatric illnesses. Among the key players in these events are glucocorticoid receptors. Dysfunctional glucocorticoid signalling may indeed contribute to psychopathology through a number of mechanisms that regulate the response to acute or chronic stress and that affect the function of genes and systems known to be relevant for mood disorders. Indeed, exposure to chronic stress early in life as well as in adulthood has been shown to reduce the expression of glucocorticoid receptors (GR), also through epigenetic mechanisms, and to up-regulate the expression of the co-chaperone gene FKBP5, which restrains GR activity by limiting the translocation of the receptor complex to the nucleus. Another mechanism that contributes to changes in GR responsiveness is the state of receptor phosphorylation that controls activation, subcellular localization as well as its transcriptional activity. Moreover, GR phosphorylation may represent an important mechanism for the cross talk between neurotrophic signalling and GR-dependent transcription, bridging two important players for mood disorders. One gene that lies downstream from GR and may contribute to stress-related changes is serum glucocorticoid kinase-1 (SGK1). We have demonstrated that the expression of SGK1 is significantly increased after exposure to chronic stress in rodents as well as in the blood of drug-free depressed patients. We have also shown that SGK1 up-regulation may ultimately reduce hippocampal neurogenesis and contribute to the structural abnormalities that have been reported to occur in depressed patients. In summary, GR signalling may represent a point of convergence as well as of divergence for defects associated with pathologic conditions characterized by heightened vulnerability to stress. The characterization of these abnormalities is crucial to identify novel targets for therapeutic intervention that may counteract more effectively stress-induced neurobiological abnormalities.
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Affiliation(s)
- A Cattaneo
- Stress, Psychiatry and Immunology Laboratory, Department of Psychological Medicine, Institute of Psychiatry, King's College London, London, UK; IRCCS Fatebenefratelli San Giovanni di Dio, Brescia, Italy
| | - M A Riva
- Laboratory of Psychopharmacology and Molecular Psychiatry, Department of Pharmacological and Biomolecular Sciences, University of Milan, Via Balzaretti 9, Milan, Italy.
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16
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Jacobs ME, Kathpalia PP, Chen Y, Thomas SV, Noonan EJ, Pao AC. SGK1 regulation by miR-466g in cortical collecting duct cells. Am J Physiol Renal Physiol 2016; 310:F1251-7. [PMID: 26911843 PMCID: PMC4935769 DOI: 10.1152/ajprenal.00024.2016] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Accepted: 02/22/2016] [Indexed: 11/22/2022] Open
Abstract
Micro-RNAs (miRNAs) are noncoding RNAs that bind target mRNA transcripts and modulate gene expression. In the cortical collecting duct (CCD), aldosterone stimulates the expression of genes that increase activity of the epithelial sodium channel (ENaC); in the early phase of aldosterone induction, one such gene is serum and glucocorticoid regulated kinase 1 (SGK1). We hypothesized that aldosterone regulates the expression of miRNAs in the early phase of induction to control the expression of target genes that stimulate ENaC activity. We treated mpkCCDc14 cells with aldosterone or vehicle for 1 h and used a miRNA microarray to analyze differential miRNA expression. We identified miR-466g as a miRNA that decreased by 57% after 1 h of aldosterone treatment. Moreover, we identified a putative miR-466g binding site in the 3'-untranslated region of SGK1. We constructed an SGK1 3'-untranslated region luciferase reporter and found that cotransfection of miR-466g suppressed luciferase activity in human embryonic kidney-293 cells in a dose-dependent manner. Deletion or introduction of point mutations that disrupt the miR-466g target site attenuated miR-466g-directed suppression of luciferase activity. Finally, we generated stably transduced mpkCCDc14 cell lines overexpressing miR-466g. Cells overexpressing miR-466g demonstrated 12.9-fold lower level of SGK1 mRNA compared with control cells after 6 h of aldosterone induction; moreover, cells overexpressing miR-466g exhibited 25% decrease in amiloride-sensitive current after 6 h of aldosterone induction and complete loss of amiloride-sensitive current after 24 h of aldosterone induction. Our findings implicate miR-466g as a novel early-phase aldosterone responsive miRNA that regulates SGK1 and ENaC in CCD cells.
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Affiliation(s)
- Mollie E Jacobs
- Department of Medicine, Stanford University School of Medicine, Stanford, California; and
| | - Paru P Kathpalia
- Department of Medicine, Stanford University School of Medicine, Stanford, California; and
| | - Yu Chen
- Veterans Affairs Palo Alto Health Care System, Palo Alto, California
| | - Sheela V Thomas
- Department of Medicine, Stanford University School of Medicine, Stanford, California; and
| | - Emily J Noonan
- Department of Medicine, Stanford University School of Medicine, Stanford, California; and Veterans Affairs Palo Alto Health Care System, Palo Alto, California
| | - Alan C Pao
- Department of Medicine, Stanford University School of Medicine, Stanford, California; and Veterans Affairs Palo Alto Health Care System, Palo Alto, California
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17
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Shimizu M, Goto T, Sato A, Shibuya H. WNK4 is an essential effector of anterior formation in FGF signaling. Genes Cells 2013; 18:442-9. [PMID: 23517227 PMCID: PMC3712470 DOI: 10.1111/gtc.12048] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2013] [Accepted: 02/17/2013] [Indexed: 11/30/2022]
Abstract
With no lysine (K) (WNK) kinase family is conserved among many species and regulates SPAK/OSR1 and ion cotransporters. WNK is also involved in developmental and cellular processes, but the molecular mechanisms underlying its regulation in these processes remain unknown. In this study, we found that WNK4 is involved in fibroblast growth factor (FGF) signaling during Xenopus development. In Xenopus embryos, depletion of WNK4 by antisense morpholino oligonucleotides (MOs) results in a severe defect in anterior development and impaired expression of endogenous anterior markers. Defects in head formation or expression of anterior marker genes caused by suppression of endogenous WNK4 expression could be rescued by expression of wild-type WNK4, but not mutant WNK4 lacking its kinase activity. It is notable that morphants of Xenopus WNK4 inhibited the expression of anterior marker genes and the target genes induced by FGF signaling. Moreover, knockdown of Wnk4 significantly reduced the phosphorylation level of Osr1 induced by FGF. These results provide the first evidence that FGF signaling regulates WNK4 function required for anterior formation in Xenopus development.
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Affiliation(s)
- Masahiro Shimizu
- Department of Molecular Cell Biology, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan
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18
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Hernández-Díaz I, Giraldez T, Morales S, Hernandez G, Salido E, Canessa CM, Alvarez de la Rosa D. Heterogeneous nuclear ribonucleoprotein A2/B1 is a tissue-specific aldosterone target gene with prominent induction in the rat distal colon. Am J Physiol Gastrointest Liver Physiol 2013; 304:G122-31. [PMID: 23139218 DOI: 10.1152/ajpgi.00130.2012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The steroid hormone aldosterone enhances transepithelial Na(+) reabsorption in tight epithelia and is crucial to achieve extracellular volume homeostasis and control of blood pressure. One of the main transport pathways regulated by aldosterone involves the epithelial Na(+) channel (ENaC), which constitutes the rate-limiting step of Na(+) reabsorption in parts of the distal nephron and the collecting duct, the distal colon, and sweat and salivary glands. Although these epithelial tissues share the same receptor for aldosterone (mineralocorticoid receptor, MR), and the same transport system (ENaC), it has become clear that the molecular mechanisms involved in the modulation of channel activity are tissue-specific. Recent evidence suggests that aldosterone controls transcription and also translation of ENaC subunits in some cell types. A possible pathway for translational regulation is binding of regulatory proteins to ENaC subunit mRNAs, such as the heterogeneous nuclear ribonucleoprotein A2/B1 (hnRNP A2/B1). In this study, we examined whether hnRNP A2/B1 is an aldosterone-target gene in vivo. Our data show that physiological levels of aldosterone markedly induce hnRNP A2/B1 expression in an early and sustained manner in the late distal colon epithelium but not in other aldosterone-target tissues. The effect depends on MR but not on glucocorticoid receptor activity. We also demonstrate that the genomic region upstream of hnRNP A2/B1 contains aldosterone-responsive elements involved in the control of gene expression. We hypothesize that hnRNP A2/B1 is involved in the tissue-specific regulation of ENaC biosynthesis and may coordinate the response of other genes relevant for transepithelial Na(+) reabsorption by aldosterone.
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Affiliation(s)
- Iván Hernández-Díaz
- Department of Physiology and Instituto de Tecnologías Biomédicas, University of La Laguna, Tenerife, Spain
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19
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Na T, Wu G, Zhang W, Dong WJ, Peng JB. Disease-causing R1185C mutation of WNK4 disrupts a regulatory mechanism involving calmodulin binding and SGK1 phosphorylation sites. Am J Physiol Renal Physiol 2012; 304:F8-F18. [PMID: 23054253 DOI: 10.1152/ajprenal.00284.2012] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The R1185C mutation in WNK4 is associated with pseudohypoaldosteronism type II (PHAII). Unlike other PHAII-causing mutations in the acidic motif, the R1185C mutation is located in the COOH-terminal region of WNK4. The goal of the study is to determine what properties of WNK4 are disrupted by the R1185C mutation. We found that the R1185C mutation is situated in the middle of a calmodulin (CaM) binding site and the mutation reduces the binding of WNK4 to Ca(2+)/CaM. The R1185C mutation is also close to serum- and glucocorticoid-induced protein kinase (SGK1) phosphorylation sites S1190 and S1217. In addition, we identified a novel SGK1 phosphorylation site (S1201) in WNK4, and phosphorylation at this site is reduced by Ca(2+)/CaM. In the wild-type WNK4, the level of phosphorylation at S1190 is the lowest and that at S1217 is the highest. In the R1185C mutant, phosphorylation at S1190 is eliminated and that at S1201 becomes the strongest. The R1185C mutation enhances the positive effect of WNK4 on the Na(+)-K(+)-2Cl(-) cotransporter 2 (NKCC2) as tested in Xenopus laevis oocytes. Deletion of the CaM binding site or phospho-mimicking at two or three of the SGK1 sites enhances the WNK4 effects on NKCC2. These results indicate that the R1185C mutation disrupts an inhibitory domain as part of the suppression mechanism of WNK4, leading to an elevated WNK4 activity at baseline. The presence of CaM binding and SGK1 phosphorylation sites in or close to the inhibitory domain suggests that WNK4 activity is subject to the regulation by intracellular Ca(2+) and phosphorylation.
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Affiliation(s)
- Tao Na
- Nephrology Research and Training Center, Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama 35294-0006, USA
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20
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Abstract
PURPOSE OF REVIEW The serum and glucocorticoid regulated kinase (SGK) family of protein kinases shares similar biochemical and hormonal signaling properties; however, the SGK kinases also exhibit distinct differences in regulating renal sodium (Na(+)) transport. This review will highlight recent advances in our understanding of the specificity of SGK kinase signaling and regulation of renal Na(+) transport. RECENT FINDINGS Differential expression of SGK kinases at the cellular and subcellular levels contributes to signaling specificity. New evidence indicates that SGK1 associates with the apical cell membrane of cortical collecting duct cells to regulate open probability of the epithelial Na(+) channel (ENaC). Scaffold proteins can also recruit SGK1 to multiprotein complexes for regulation of ENaC expression in the apical membrane. Recent SGK1 knockout models have implicated the NaCl co-transporter (NCC) as another target of SGK1 regulation. Less is known about the function of SGK2 or SGK3, but both kinases can regulate Na(+)/H(+) exchanger 3 (NHE3) activity. SUMMARY The SGK kinases assume distinct roles in regulating Na transport in both proximal and distal elements of the kidney tubule. Future examination of the molecular mechanisms by which the SGK kinases regulate specific substrates will inform our understanding of how these kinases contribute to the physiology of renal Na(+) transport.
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Affiliation(s)
- Alan C Pao
- Division of Nephrology, Department of Medicine, Stanford University School of Medicine, Stanford, California, USA
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21
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Lienhard D, Lauterburg M, Escher G, Frey FJ, Frey BM. High salt intake down-regulates colonic mineralocorticoid receptors, epithelial sodium channels and 11β-hydroxysteroid dehydrogenase type 2. PLoS One 2012; 7:e37898. [PMID: 22693583 PMCID: PMC3365073 DOI: 10.1371/journal.pone.0037898] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Accepted: 04/26/2012] [Indexed: 11/18/2022] Open
Abstract
Besides the kidneys, the gastrointestinal tract is the principal organ responsible for sodium homeostasis. For sodium transport across the cell membranes the epithelial sodium channel (ENaC) is of pivotal relevance. The ENaC is mainly regulated by mineralocorticoid receptor mediated actions. The MR activation by endogenous 11β-hydroxy-glucocorticoids is modulated by the 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2). Here we present evidence for intestinal segment specific 11β-HSD2 expression and hypothesize that a high salt intake and/or uninephrectomy (UNX) affects colonic 11β-HSD2, MR and ENaC expression. The 11β-HSD2 activity was measured by means of 3H-corticosterone conversion into 3H-11-dehydrocorticosterone in Sprague Dawley rats on a normal and high salt diet. The activity increased steadily from the ileum to the distal colon by a factor of about 3, an observation in line with the relevance of the distal colon for sodium handling. High salt intake diminished mRNA and protein of 11β-HSD2 by about 50% (p<0.001) and reduced the expression of the MR (p<0.01). The functionally relevant ENaC-β and ENaC-γ expression, a measure of mineralocorticoid action, diminished by more than 50% by high salt intake (p<0.001). The observed changes were present in rats with and without UNX. Thus, colonic epithelial cells appear to contribute to the protective armamentarium of the mammalian body against salt overload, a mechanism not modulated by UNX.
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Affiliation(s)
- Daniel Lienhard
- Department of Nephrology and Hypertension, University Hospital of Berne, Berne, Switzerland
| | - Meret Lauterburg
- Department of Nephrology and Hypertension, University Hospital of Berne, Berne, Switzerland
| | - Geneviève Escher
- Department of Nephrology and Hypertension, University Hospital of Berne, Berne, Switzerland
| | - Felix J. Frey
- Department of Nephrology and Hypertension, University Hospital of Berne, Berne, Switzerland
| | - Brigitte M. Frey
- Department of Nephrology and Hypertension, University Hospital of Berne, Berne, Switzerland
- Department of Clinical Research, University Hospital of Berne, Berne, Switzerland
- * E-mail:
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22
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Lin DH, Yue P, Rinehart J, Sun P, Wang Z, Lifton R, Wang WH. Protein phosphatase 1 modulates the inhibitory effect of With-no-Lysine kinase 4 on ROMK channels. Am J Physiol Renal Physiol 2012; 303:F110-9. [PMID: 22513846 DOI: 10.1152/ajprenal.00676.2011] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
With-no-Lysine kinase 4 (WNK4) inhibited ROMK (Kir1.1) channels and the inhibitory effect of WNK4 was abolished by serum-glucocorticoid-induced kinase 1 (SGK1) but restored by c-Src. The aim of the present study is to explore the mechanism by which Src-family tyrosine kinase (SFK) modulates the effect of SGK1 on WNK4 and to test the role of SFK-WNK4-SGK1 interaction in regulating ROMK channels in the kidney. Immunoprecipitation demonstrated that protein phosphatase 1 (PP1) binds to WNK4 at amino acid (aa) residues 695-699 (PP1(#1)) and at aa 1211-1215 (PP1(#2)). WNK4(-PP1#1) and WNK4(-PP1#2), in which the PP1(#1) or PP1(#2) binding site was deleted or mutated, inhibited ROMK channels as potently as WNK4. However, c-Src restored the inhibitory effect of WNK4 but not WNK4(-PP1#1) on ROMK channels in the presence of SGK1. Moreover, expression of c-Src inhibited SGK1-induced phosphorylation of WNK4 but not WNK4(-PP1#1) at serine residue 1196 (Ser(1196)). In contrast, coexpression of c-Src restored the inhibitory effect of WNK4(-PP1#2) on ROMK in the presence of SGK1 and diminished SGK1-induced WNK4 phosphorylation at Ser(1196) in cells transfected with WNK4(-PP1#2). This suggests the possibility that c-Src regulates the interaction between WNK4 and SGK1 through activating PP1 binding to aa 695-9 thereby decreasing WNK4 phosphorylation and restoring the inhibitory effect of WNK4. This mechanism plays a role in suppressing ROMK channel activity during the volume depletion because inhibition of SFK or serine/threonine phosphatases increases ROMK channel activity in the cortical collecting duct of rats on a low-Na diet. We conclude that regulation of phosphatase activity by SFK plays a role in determining the effect of aldosterone on ROMK channels and on renal K secretion.
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Affiliation(s)
- Dao-Hong Lin
- Department of Pharmacology, New York Medical College, Valhalla, New York 10595, USA
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23
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Martín-Fernández B, de las Heras N, Miana M, Ballesteros S, Valero-Muñoz M, Vassallo D, Davel AP, Rossoni LV, Cachofeiro V, Lahera V. Spironolactone prevents alterations associated with cardiac hypertrophy produced by isoproterenol in rats: involvement of serum- and glucocorticoid-regulated kinase type 1. Exp Physiol 2012; 97:710-8. [PMID: 22327331 DOI: 10.1113/expphysiol.2011.063230] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Persistent β-adrenergic receptor stimulation with isoproterenol is associated with cardiac hypertrophy as well as cardiac synthesis of angiotensin II. Serum- and glucocorticoid-regulated kinase type 1 (SGK-1) is a key mediator in structural, functional and molecular cardiac effects of aldosterone in rats. This study was designed to investigate the cardiac effects of the mineralocorticoid receptor antagonist spironolactone on the response to isoproterenol treatment in rats, as well as the involvement of the main mediator of cellular aldosterone action, SGK-1, in the heart. Male Wistar rats received isoproterenol (3 mg kg(-1) day(-1)) or vehicle for 15 days. Half of the animals in each group were simultaneously treated with spironolactone (200 mg kg(-1) day(-1)). Systolic and diastolic blood pressures were not significantly different among groups. Treatment with spironolactone normalized the increased left ventricular end-diastolic pressure observed in isoproterenol-treated rats. Isoproterenol treatment induced cardiac hypertrophy and increased collagen content, both of which were normalized by spironolactone treatment. The mRNA levels of transforming growth factor β, connective tissue growth factor, matrix metalloprotease 2, matrix metalloprotease inhibitor 2, tumour necrosis factor α, interleukin 1β, p22phox and xanthine dehydrogenase were increased (P < 0.05) in isoproterenol-treated rats, and this effect was prevented by spironolactone (P < 0.05). Spironolactone also reduced the elevated SGK-1 expression in isoproterenol-treated rats. The observed reduction of the principal mediator of aldosterone cellular actions, SGK-1, by spironolactone in hearts from isoproterenol-treated rats suggests a role of mineralocorticoids in the cardiac hypertrophy, fibrosis, inflammation, oxidation and diastolic dysfunction induced by isoproterenol treatment in rats.
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Structural, functional, and molecular alterations produced by aldosterone plus salt in rat heart: association with enhanced serum and glucocorticoid-regulated kinase-1 expression. J Cardiovasc Pharmacol 2011; 57:114-21. [PMID: 20980916 DOI: 10.1097/fjc.0b013e31820088ca] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
We aimed to evaluate the structural, functional, inflammatory, and oxidative alterations, as well as serum and glucocorticoid-regulated kinase-1 (SGK-1) expression, produced in rat heart by aldosterone + salt administration. Fibrosis mediators such as connective tissue growth factor, matrix metalloproteinase 2, and tissue inhibitor of metalloproteinases 2 were also evaluated. Treatment with spironolactone was evaluated to prove mineralocorticoid mediation. Male Wistar rats received aldosterone (1 mg[middle dot]kg-1[middle dot]d-1) + 1% NaCl for 3 weeks. Half of the animals were treated with spironolactone (200 mg[middle dot]kg-1[middle dot]d-1). Systolic and diastolic blood pressures, left ventricle (LV) systolic pressure, and LV end-diastolic pressure were elevated (P < 0.05) in aldosterone + salt-treated rats. In aldosterone + salt-treated rats, -dP/dt decreased (P < 0.05), but +dP/dt was similar in all groups. Spironolactone normalized (P < 0.05) systolic blood pressure, diastolic blood pressure, LV systolic pressure, LV end-diastolic pressure, and -dP/dt. Relative heart weight, collagen content, messenger RNA expression of transforming growth factor beta, connective tissue growth factor, matrix metalloproteinase 2, tissue inhibitor of metalloproteinases 2, tumor necrosis factor alpha, interleukin-1[beta], p22phox, endothelial nitric oxide synhtase, and SGK-1 were increased (P < 0.05) in aldosterone + salt-treated rats, being reduced by spironolactone (P < 0.05). SGK-1 might be a key mediator in the structural, functional, and molecular cardiac alterations induced by aldosterone + salt in rats. All the observed changes and mediators are related with the activation of mineralocorticoid receptors.
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Pao AC, Bhargava A, Di Sole F, Quigley R, Shao X, Wang J, Thomas S, Zhang J, Shi M, Funder JW, Moe OW, Pearce D. Expression and role of serum and glucocorticoid-regulated kinase 2 in the regulation of Na+/H+ exchanger 3 in the mammalian kidney. Am J Physiol Renal Physiol 2010; 299:F1496-506. [PMID: 20926631 PMCID: PMC3006302 DOI: 10.1152/ajprenal.00075.2010] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2010] [Accepted: 09/14/2010] [Indexed: 01/30/2023] Open
Abstract
Serum and glucocorticoid-regulated kinase 2 (sgk2) is 80% identical to the kinase domain of sgk1, an important mediator of mineralocorticoid-regulated sodium (Na(+)) transport in the distal nephron of the kidney. The expression pattern and role in renal function of sgk2 are virtually uncharacterized. In situ hybridization and immunohistochemistry of rodent kidney coupled with real-time RT-PCR of microdissected rat kidney tubules showed robust sgk2 expression in the proximal straight tubule and thick ascending limb of the loop of Henle. Sgk2 expression was minimal in distal tubule cells with aquaporin-2 immunostaining but significant in proximal tubule cells with Na(+)/H(+) exchanger 3 (NHE3) immunostaining. To ascertain whether mineralocorticoids regulate expression of sgk2 in a manner similar to sgk1, we examined sgk2 mRNA expression in the kidneys of adrenalectomized rats treated with physiological doses of aldosterone together with the glucocorticoid receptor antagonist RU486. Northern blot analysis and in situ hybridization showed that, unlike sgk1, sgk2 expression in the kidney was not altered by aldosterone treatment. Based on the observation that sgk2 is expressed in proximal tubule cells that also express NHE3, we asked whether sgk2 regulates NHE3 activity. We heterologously expressed sgk2 in opossum kidney (OKP) cells and measured Na(+)/H(+) exchange activity by Na(+)-dependent cell pH recovery. Constitutively active sgk2, but not sgk1, stimulated Na(+)/H(+) exchange activity by >30%. Moreover, the sgk2-mediated increase in Na(+)/H(+) exchange activity correlated with an increase in cell surface expression of NHE3. Together, these results suggest that the pattern of expression, regulation, and role of sgk2 within the mammalian kidney are distinct from sgk1 and that sgk2 may play a previously unrecognized role in the control of transtubular Na(+) transport through NHE3 in the proximal tubule.
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Affiliation(s)
- Alan C Pao
- Div. of Nephrology, Dept. of Medicine, Stanford Univ., 780 Welch Rd., Suite 106, Palo Alto, CA 94304, USA.
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Lessi F, Beggs A, de Palo M, Anti M, Macarone Palmieri R, Francesconi S, Gomes V, Bevilacqua G, Tomlinson I, Segditsas S. Down-regulation of serum/glucocorticoid regulated kinase 1 in colorectal tumours is largely independent of promoter hypermethylation. PLoS One 2010; 5:e13840. [PMID: 21079778 PMCID: PMC2974649 DOI: 10.1371/journal.pone.0013840] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2010] [Accepted: 10/14/2010] [Indexed: 01/28/2023] Open
Abstract
Background We have previously shown that serum/glucocorticoid regulated kinase 1 (SGK1) is down-regulated in colorectal cancers (CRC) with respect to normal tissue. As hyper-methylation of promoter regions is a well-known mechanism of gene silencing in cancer, we tested whether the SGK1 promoter region was methylated in colonic tumour samples. Methodology/Principal Findings We investigated the methylation profile of the two CpG islands present in the promoter region of SGK1 in a panel of 5 colorectal cancer cell lines by sequencing clones of bisulphite-treated DNA samples. We further confirmed our findings in a panel of 10 normal and 10 tumour colonic tissue samples of human origin. We observed CpG methylation only in the smaller and more distal CpG island in the promoter region of SGK1 in both normal and tumour samples of colonic origin. We further identified a single nucleotide polymorphism (SNP, rs1743963) which affects methylation of the corresponding CpG. Conclusions/Significance Our results show that even though partial methylation of the promoter region of SGK1 is present, this does not account for the different expression levels seen between normal and tumour tissue.
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Affiliation(s)
- Francesca Lessi
- Molecular and Population Genetics Laboratory, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
- Division of Surgical, Molecular and Ultrastructural Pathology, Department of Oncology, University of Pisa and Pisa University Hospital, Pisa, Italy
| | - Andrew Beggs
- Molecular and Population Genetics Laboratory, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | | | - Marcello Anti
- Presidio Ospedaliero Belcolle Viterbo, Viterbo, Italy
| | | | | | - Vito Gomes
- Presidio Ospedaliero Belcolle Viterbo, Viterbo, Italy
| | - Generoso Bevilacqua
- Division of Surgical, Molecular and Ultrastructural Pathology, Department of Oncology, University of Pisa and Pisa University Hospital, Pisa, Italy
| | - Ian Tomlinson
- Molecular and Population Genetics Laboratory, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Stefania Segditsas
- Molecular and Population Genetics Laboratory, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
- * E-mail:
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Hyperaldosteronism and altered expression of an SGK1-dependent sodium transporter in ZDF rats leads to salt dependence of blood pressure. Hypertens Res 2010; 33:1082-8. [DOI: 10.1038/hr.2010.132] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Mohammed SF, Ohtani T, Korinek J, Lam CSP, Larsen K, Simari RD, Valencik ML, Burnett JC, Redfield MM. Mineralocorticoid accelerates transition to heart failure with preserved ejection fraction via "nongenomic effects". Circulation 2010; 122:370-8. [PMID: 20625113 DOI: 10.1161/circulationaha.109.915215] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Mechanisms promoting the transition from hypertensive heart disease to heart failure with preserved ejection fraction are poorly understood. When inappropriate for salt status, mineralocorticoid (deoxycorticosterone acetate) excess causes hypertrophy, fibrosis, and diastolic dysfunction. Because cardiac mineralocorticoid receptors are protected from mineralocorticoid binding by the absence of 11-beta hydroxysteroid dehydrogenase, salt-mineralocorticoid-induced inflammation is postulated to cause oxidative stress and to mediate cardiac effects. Although previous studies have focused on salt/nephrectomy in accelerating mineralocorticoid-induced cardiac effects, we hypothesized that hypertensive heart disease is associated with oxidative stress and sensitizes the heart to mineralocorticoid, accelerating hypertrophy, fibrosis, and diastolic dysfunction. METHODS AND RESULTS Cardiac structure and function, oxidative stress, and mineralocorticoid receptor-dependent gene transcription were measured in sham-operated and transverse aortic constriction (studied 2 weeks later) mice without and with deoxycorticosterone acetate administration, all in the setting of normal-salt diet. Compared with sham mice, sham plus deoxycorticosterone acetate mice had mild hypertrophy without fibrosis or diastolic dysfunction. Transverse aortic constriction mice displayed compensated hypertensive heart disease with hypertrophy, increased oxidative stress (osteopontin and NOX4 gene expression), and normal systolic function, filling pressures, and diastolic stiffness. Compared with transverse aortic constriction mice, transverse aortic constriction plus deoxycorticosterone acetate mice had similar left ventricular systolic pressure and fractional shortening but more hypertrophy, fibrosis, and diastolic dysfunction with increased lung weights, consistent with heart failure with preserved ejection fraction. There was progressive activation of markers of oxidative stress across the groups but no evidence of classic mineralocorticoid receptor-dependent gene transcription. CONCLUSIONS Pressure-overload hypertrophy sensitizes the heart to mineralocorticoid excess, which promotes the transition to heart failure with preserved ejection fraction independently of classic mineralocorticoid receptor-dependent gene transcription.
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Affiliation(s)
- Selma F Mohammed
- Cardiovascular Research, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA
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Src family protein tyrosine kinase (PTK) modulates the effect of SGK1 and WNK4 on ROMK channels. Proc Natl Acad Sci U S A 2009; 106:15061-6. [PMID: 19706464 DOI: 10.1073/pnas.0907855106] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
WNK4 (with no lysine kinase 4) inhibits ROMK channel activity in the distal nephron by stimulating clathrin-dependent endocytosis, an effect attenuated by SGK1 (serum-glucocorticoids-induced kinase)-mediated phosphorylation. It has been suggested that increased ROMK activity because of SGK1-mediated inhibition of WNK4 plays a role in promoting renal K secretion in response to elevated serum K or high K (HK) intake. In contrast, intravascular volume depletion also increases SGK1 activity but fails to stimulate ROMK channels and K secretion. Because HK intake decreases Src family protein tyrosine kinase (PTK) activity an inhibitor of ROMK channels, it is possible that Src family PTK may modulate the effects of SGK1 on WNK4. Here, we show that c-Src prevents SGK1 from attenuating WNK4's inhibition of ROMK activity. This effect of c-Src was WNK4-dependent because c-Src had no effect on ROMK harboring mutation at the site of c-Src phosphorylation (R1Y337A) in the absence of WNK4. Moreover, expression c-Src diminished the SGK1-mediated increase in serine phosphorylation of WNK4, suggesting that c-Src enhances WNK4-mediated inhibition of ROMK channels by suppressing the SGK1-induced phosphorylation. This notion is also supported by the observation that c-Src was not able to modulate the interaction between SGK1 and WNK4 mutants (WNK4(S1169A) or WNK4(S1169D)) in which an SGK1-phosphorylation site (serine 1169) was mutated by alanine or aspartate. We conclude that c-Src inhibits SGK1-mediated phosphorylation hereby restoring the WNK4-mediated inhibition of ROMK channels thus suppressing K secretion.
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Luca F, Kashyap S, Southard C, Zou M, Witonsky D, Di Rienzo A, Conzen SD. Adaptive variation regulates the expression of the human SGK1 gene in response to stress. PLoS Genet 2009; 5:e1000489. [PMID: 19461886 PMCID: PMC2679193 DOI: 10.1371/journal.pgen.1000489] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2009] [Accepted: 04/22/2009] [Indexed: 12/22/2022] Open
Abstract
The Serum and Glucocorticoid-regulated Kinase1 (SGK1) gene is a target of the glucocorticoid receptor (GR) and is central to the stress response in many human tissues. Because environmental stress varies across habitats, we hypothesized that natural selection shaped the geographic distribution of genetic variants regulating the level of SGK1 expression following GR activation. By combining population genetics and molecular biology methods, we identified a variant (rs9493857) with marked allele frequency differences between populations of African and European ancestry and with a strong correlation between allele frequency and latitude in worldwide population samples. This SNP is located in a GR-binding region upstream of SGK1 that was identified using a GR ChIP-chip. SNP rs9493857 also lies within a predicted binding site for Oct1, a transcription factor known to cooperate with the GR in the transactivation of target genes. Using ChIP assays, we show that both GR and Oct1 bind to this region and that the ancestral allele at rs9493857 binds the GR-Oct1 complex more efficiently than the derived allele. Finally, using a reporter gene assay, we demonstrate that the ancestral allele is associated with increased glucocorticoid-dependent gene expression when compared to the derived allele. Our results suggest a novel paradigm in which hormonal responsiveness is modulated by sequence variation in the regulatory regions of nuclear receptor target genes. Identifying such functional variants may shed light on the mechanisms underlying inter-individual variation in response to environmental stressors and to hormonal therapy, as well as in the susceptibility to hormone-dependent diseases. Susceptibility to many common human diseases including hypertension, heart disease, and the metabolic syndrome is associated with increased neuroendocrine signaling in response to environmental stressors. A key component of the human stress response involves increased systemic glucocorticoid secretion that in turn leads to glucocorticoid receptor (GR) activation. As a result, a variety of GR-expressing cell types undergo gene expression changes, thereby providing an integrated physiological response to stress. The SGK1 gene is a well-established GR target that promotes cellular homeostasis in response to stress. Here, we use a combination of population genetics and molecular biology approaches to identify an SNP (rs9493857) in a distant SGK1 GR-binding region with unusually large differences in allele frequency between populations of European and African ancestry. Furthermore, rs9493857 shows a strong correlation between allele frequency and distance from the equator, a pattern consistent with a varying selective advantage across environments. Indeed, the ancestral allele at rs9493857 results in increased GR-binding and glucocorticoid-regulated gene expression, suggesting that an increased stress response (i.e., glucocorticoid responsiveness) was advantageous in ancestral human populations. We speculate that, in modern times, such variation could favor the negative effects of a heightened glucocorticoid response, potentially predisposing individuals to chronic diseases such as metabolic syndrome and hypertension.
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Affiliation(s)
- Francesca Luca
- Department of Human Genetics, The University of Chicago, Chicago, Illinois, United States of America
| | - Sonal Kashyap
- Department of Medicine, The University of Chicago, Chicago, Illinois, United States of America
| | - Catherine Southard
- Department of Human Genetics, The University of Chicago, Chicago, Illinois, United States of America
| | - Min Zou
- Department of Medicine, The University of Chicago, Chicago, Illinois, United States of America
| | - David Witonsky
- Department of Human Genetics, The University of Chicago, Chicago, Illinois, United States of America
| | - Anna Di Rienzo
- Department of Human Genetics, The University of Chicago, Chicago, Illinois, United States of America
- * E-mail: (ADR); (SDC)
| | - Suzanne D. Conzen
- Department of Medicine, The University of Chicago, Chicago, Illinois, United States of America
- * E-mail: (ADR); (SDC)
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Ackermann TF, Boini KM, Völkl H, Bhandaru M, Bareiss PM, Just L, Vallon V, Amann K, Kuhl D, Feng Y, Hammes HP, Lang F. SGK1-sensitive renal tubular glucose reabsorption in diabetes. Am J Physiol Renal Physiol 2009; 296:F859-66. [PMID: 19158347 DOI: 10.1152/ajprenal.90238.2008] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The hyperglycemia of diabetes mellitus increases the filtered glucose load beyond the maximal tubular transport rate and thus leads to glucosuria. Sustained hyperglycemia, however, may gradually increase the maximal renal tubular transport rate and thereby blunt the increase of urinary glucose excretion. The mechanisms accounting for the increase of renal tubular glucose transport have remained ill-defined. A candidate is the serum- and glucocorticoid-inducible kinase SGK1. The kinase has been shown to stimulate Na(+)-coupled glucose transport in vitro and mediate the stimulation of electrogenic intestinal glucose transport by glucocorticoids in vivo. SGK1 expression is confined to glomerula and distal nephron in intact kidneys but may extend to the proximal tubule in diabetic nephropathy. To explore whether SGK1 modifies glucose transport in diabetic kidneys, Akita mice (akita(+/-)), which develop spontaneous diabetes, have been crossbred with gene-targeted mice lacking SGK1 on one allele (sgk1(+/-)) to eventually generate either akita(+/-)/sgk1(-/-) or akita(+/-)/sgk1(+/+) mice. Both akita(+/-)/sgk1(-/-) and akita(+/-)/sgk1(+/+) mice developed profound hyperglycemia (>20 mM) within approximately 6 wk. Body weight and plasma glucose concentrations were not significantly different between these two genotypes. However, urinary excretion of glucose and urinary excretion of fluid, Na(+), and K(+), as well as plasma aldosterone concentrations, were significantly higher in akita(+/-)/sgk1(-/-) than in akita(+/-)/sgk1(+/+) mice. Studies in isolated perfused proximal tubules revealed that the electrogenic glucose transport was significantly lower in akita(+/-)/sgk1(-/-) than in akita(+/-)/sgk1(+/+) mice. The data provide the first evidence that SGK1 participates in the stimulation of renal tubular glucose transport in diabetic kidneys.
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Affiliation(s)
- Teresa F Ackermann
- Dept. of Physiology, Univ. of Tübingen, Gmelinstr. 5, D-72076 Tübingen, Germany
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Physiologic regulation of the epithelial sodium channel by phosphatidylinositides. Curr Opin Nephrol Hypertens 2009; 17:533-40. [PMID: 18695396 DOI: 10.1097/mnh.0b013e328308fff3] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
PURPOSE OF REVIEW Epithelial sodium channel (ENaC) activity is limiting for sodium reabsorption in the distal nephron. Humans regulate blood pressure by fine-tuning sodium balance through control of ENaC. ENaC dysfunction causes some hypertensive and renal salt wasting diseases. Thus, it is critical to understand the cellular mechanisms controlling ENaC activity. RECENT FINDINGS ENaC is sensitive to phosphatidylinositol 4,5-bisphosphate (PIP2), the target of phospholipase C-mediated metabolism, and phosphatidylinositiol 3,4,5-trisphosphate (PIP3), the product of phosphatidylinositide 3-OH kinase (PI3-K). PIP2 is permissive for ENaC gating possibly interacting directly with the channel. Activation of distal nephron P2Y receptors tempers ENaC activity by promoting PIP2 metabolism. This is important because gene deletion of P2Y2 receptors causes hypertension associated with hyperactive ENaC. Aldosterone, the final hormone in a negative-feedback cascade activated by decreases in blood pressure, increases ENaC activity. PIP3 sits at a critical bifurcation in the aldosterone-signaling cascade, increasing ENaC open probability and number. PIP3-effectors mediate increases in ENaC number by suppressing channel retrieval. PIP3 binds ENaC, at a site distinct from that important to PIP2 regulation, to modulate directly open probability. SUMMARY Phosphoinositides play key roles in physiologic control of ENaC and perhaps dysregulation plays a role in disease associated with abnormal renal sodium handling.
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Gabor A, Leenen FHH. Mechanisms in the PVN mediating local and central sodium-induced hypertension in Wistar rats. Am J Physiol Regul Integr Comp Physiol 2008; 296:R618-30. [PMID: 19109373 DOI: 10.1152/ajpregu.90417.2008] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Sympathoexcitatory and hypertensive responses to central infusion of Na(+)-rich artificial cerebrospinal fluid (aCSF) are enhanced by aldosterone and mediated by mineralocorticoid receptors (MRs) and benzamil-blockable Na(+) influx, leading to "ouabain" release and ANG II type 1 (AT(1)) receptor stimulation. The present study evaluated the functional role of these mechanisms in the paraventricular nucleus (PVN). In conscious Wistar rats, Na(+)-rich aCSF was infused either directly into the PVN or intracerebroventricularly preceded by aldosterone and blockers. Infusion of Na(+)-rich aCSF in the PVN caused gradual increases in blood pressure (BP) and heart rate (HR). Aldosterone and a subpressor dose of ouabain in the PVN alone did not affect BP and HR but enhanced responses to Na(+). Eplerenone, benzamil, and "ouabain"-binding Fab fragments only blocked the enhancement by aldosterone, whereas losartan blocked all responses to Na(+)-rich aCSF in the PVN. Increases in BP and HR by intracerebroventricular infusion of Na(+)-rich aCSF were enhanced by aldosterone infused intracerebroventricularly, but not in the PVN. Telmisartan in the PVN again blocked all responses. In contrast, both eplerenone and benzamil in the PVN did not change the pressor responses to intracerebroventricular infusion of aldosterone and Na(+)-rich aCSF. These findings indicate that AT(1) receptors in the PVN mediate the responses to Na(+)-rich aCSF and their enhancement by aldosterone, both locally in the PVN or in the general CSF. MRs, benzamil-blockable Na(+) channels or transporters, and "ouabain" can be functionally active in the PVN, but in Wistar rats appear not to contribute to the pressor responses to short-term increases in CSF [Na(+)].
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Artunc F, Nasir O, Amann K, Boini KM, Häring HU, Risler T, Lang F. Serum- and glucocorticoid-inducible kinase 1 in doxorubicin-induced nephrotic syndrome. Am J Physiol Renal Physiol 2008; 295:F1624-34. [PMID: 18768591 DOI: 10.1152/ajprenal.00032.2008] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Doxorubicin-induced nephropathy leads to epithelial sodium channel (ENaC)-dependent volume retention and renal fibrosis. The aldosterone-sensitive serum- and glucocorticoid-inducible kinase SGK1 has been shown to participate in the stimulation of ENaC and to mediate renal fibrosis following mineralocorticoid and salt excess. The present study was performed to elucidate the role of SGK1 in the volume retention and fibrosis during nephrotic syndrome. To this end, doxorubicin (15 mug/g body wt) was injected intravenously into gene-targeted mice lacking SGK1 (sgk1(-/-)) and their wild-type littermates (sgk1(+/+)). Doxorubicin treatment resulted in heavy proteinuria (>100 mg protein/mg crea) in 15/44 of sgk1(+/+) and 15/44 of sgk1(-/-) mice leading to severe nephrotic syndrome with ascites, lipidemia, and hypoalbuminemia in both genotypes. Plasma aldosterone levels increased in nephrotic mice of both genotypes and was followed by increased SGK1 protein expression in sgk1(+/+) mice. Urinary sodium excretion reached signficantly lower values in sgk1(+/+) mice (15 +/- 5 mumol/mg crea) than in sgk1(-/-) mice (35 +/- 5 mumol/mg crea) and was associated with a significantly higher body weight gain in sgk1(+/+) compared with sgk1(-/-) mice (+6.6 +/- 0.7 vs. +4.1 +/- 0.8 g). During the course of nephrotic syndrome, serum urea concentrations increased significantly faster in sgk1(-/-) mice than in sgk1(+/+) mice leading to uremia and a reduced median survival in sgk1(-/-) mice (29 vs. 40 days in sgk1(+/+) mice). In conclusion, gene-targeted mice lacking SGK1 showed blunted volume retention, yet were not protected against renal fibrosis during experimental nephrotic syndrome.
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Affiliation(s)
- Ferruh Artunc
- Dept. of Physiology, Univ. Hospital of Tübingen, Otfried-Mueller-Str. 10, 72076 Tübingen, Germany.
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SGK1 dependence of insulin induced hypokalemia. Pflugers Arch 2008; 457:955-61. [PMID: 18665390 DOI: 10.1007/s00424-008-0559-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2008] [Revised: 06/23/2008] [Accepted: 07/11/2008] [Indexed: 12/23/2022]
Abstract
Insulin stimulates cellular K+ uptake leading to hypokalemia. Cellular K+ uptake is accomplished by parallel stimulation of Na+/H+ exchange, Na+,K+,2Cl- co-transport, and Na+/K+ ATPase and leads to cell swelling, a prerequisite for several metabolic effects of the hormone. Little is known about underlying signaling. Insulin is known to activate the serum and glucocorticoid-inducible kinase SGK1, which in turn enhances the activity of all three transport proteins. The present study thus explored the contribution of SGK1 to insulin-induced hypokalemia. To this end, gene-targeted mice lacking SGK1 (sgk1-/-) and their wild-type littermates (sgk1+/+) have been infused with insulin (2 mU kg(-1) min(-1)) and glucose at rates leaving the plasma glucose concentration constant. Moreover, isolated liver perfusion experiments have been performed to determine stimulation of cellular K+ uptake by insulin (100 nM). As a result, combined glucose and insulin infusion significantly decreased plasma K+ concentration despite a significant decrease of urinary K+ excretion in sgk1+/+ but not in sgk1-/- mice. Accordingly, the plasma K+ concentration was within 60 min significantly lower in sgk1+/+ than in sgk1-/- mice. In isolated liver perfusion experiments, cellular K+ uptake was stimulated by insulin (100 nM), an effect blunted by 72% in sgk1-/- mice as compared to sgk1+/+ mice. Accordingly, insulin-induced cell hydration was 63% lower in sgk1-/- mice than in sgk1+/+ mice. Moreover, volume regulatory K+ release was 31% smaller in sgk1-/- mice than in sgk1+/+ mice. In conclusion, the serum and glucocorticoid-inducible kinase SGK1 participates in the signaling mediating the hypokalemic effect of insulin.
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Wang J, Knight ZA, Fiedler D, Williams O, Shokat KM, Pearce D. Activity of the p110-alpha subunit of phosphatidylinositol-3-kinase is required for activation of epithelial sodium transport. Am J Physiol Renal Physiol 2008; 295:F843-50. [PMID: 18653476 DOI: 10.1152/ajprenal.90348.2008] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The pathways implicated in the control of epithelial Na(+) channel (ENaC)-dependent Na(+) transport in renal collecting duct cells share substantial parallels with those implicated in insulin-regulated glucose metabolism. Notably, both are inhibited by wortmannin and LY294002 and signal through phosphatidylinositol-3-kinase (PI3K)-dependent kinases SGK1 and Akt. The inhibitor pattern is thought to reflect dependence on PI3K activity since wortmannin and LY294002 are both effective inhibitors of this kinase. However, these inhibitors block a variety of kinases from different families and lack specificity within the PI3K family. To begin to dissect more precisely the pathways required for signaling and for control of Na(+) transport in renal collecting duct cells, we have examined the effect of a set of PI3K inhibitors, which selectively block distinct subsets of PI3K catalytic subunit isoforms. We have found that ENaC-dependent Na(+) transport was blocked by inhibitors of the p110-alpha isoform of PI3K, but not by inhibitors of p110-beta, -gamma, or -delta. Inhibitors that block Na(+) current also blocked SGK1 and Akt phosphorylation. In contrast to insulin-stimulated glucose uptake in muscle cells, p110-beta inhibition did not enhance sensitivity to p110-alpha inhibition. These data support the conclusion that ENaC-dependent Na(+) current is controlled exclusively by p110-alpha, the same isoform that is the principal mediator of insulin effects on glucose metabolism, and lacks any dependence on p110-beta. These findings further underscore the extent to which Na(+) and glucose regulation are intertwined and provide additional insight into the interconnections between diabetes and hypertension.
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Affiliation(s)
- Jian Wang
- Division of Nephrology, Department of Medicine, San Francisco General Hospital, 1001 Potrero Avenue, San Francisco, CA 94110, USA
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Dehner M, Hadjihannas M, Weiske J, Huber O, Behrens J. Wnt signaling inhibits Forkhead box O3a-induced transcription and apoptosis through up-regulation of serum- and glucocorticoid-inducible kinase 1. J Biol Chem 2008; 283:19201-10. [PMID: 18487207 DOI: 10.1074/jbc.m710366200] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
In human cancers, mutations in components of the Wnt signaling pathway lead to beta-catenin stabilization and result in augmented gene transcription. HCT116 colon cancer cells carry stabilizing mutations in beta-catenin and exhibit an elevated activation of Wnt signaling. To clarify the role of an overactive Wnt signaling, we used DNA microarray analysis to search for genes whose expression is up-regulated after knockdown of the wild type adenomatous polyposis coli (APC) tumor suppressor in HCT116 cells, which further enhances Wnt signaling activation. Serum and glucocorticoid-inducible kinase 1 (SGK1) was among the most up-regulated genes following APC knockdown through small interfering RNA. Up-regulation of SGK1 in response to small interfering RNA against APC was inhibited by concomitant knockdown of beta-catenin. Quantitative real time reverse transcription-PCR, Western blot, and chromatin immunoprecipitation analyses confirmed that SGK1 is a direct beta-catenin target gene. SGK1 negatively regulates the pro-apoptotic transcription factor Forkhead box O3a (FoxO3a) via phosphorylation and exclusion from the nucleus. We show that Wnt signaling activation results in FoxO3a exclusion from the nucleus and inhibits expression of FoxO3a target genes. Importantly, FoxO3a mutants that fail to be phosphorylated and therefore are regulated by SGK1 are not influenced by activation of Wnt signaling. In line, knockdown of SGK1 relieves the effects of Wnt signaling on FoxO3a localization and FoxO3a-dependent transcription. Finally, we show that induction of Wnt signaling inhibits FoxO3a-induced apoptosis. Collectively our results indicate that evasion of apoptosis is another feature employed by an overactive Wnt signaling.
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Affiliation(s)
- Manuel Dehner
- Department of Experimental Medicine II, Nikolaus-Fiebiger-Center for Molecular Medicine, University of Erlangen, Glueckstrasse 6, 91054 Erlangen, Germany
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Lee IH, Campbell CR, Cook DI, Dinudom A. Regulation of epithelial Na+ channels by aldosterone: role of Sgk1. Clin Exp Pharmacol Physiol 2008; 35:235-41. [PMID: 18197893 DOI: 10.1111/j.1440-1681.2007.04844.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
1. The epithelial sodium channel (ENaC) is tightly regulated by hormonal and humoral factors, including cytosolic ion concentration and glucocorticoid and mineralocorticoid hormones. Many of these regulators of ENaC control its activity by regulating its surface expression via neural precursor cell-expressed developmentally downregulated (gene 4) protein (Nedd4-2). 2. During the early phase of aldosterone action, Nedd4-2-dependent downregulation of ENaC is inhibited by the serum- and glucocorticoid-induced kinase 1 (Sgk1). 3. Sgk1 phosphorylates Nedd4-2. Subsequently, phosphorylated Nedd4-2 binds to the 14-3-3 protein and, hence, reduces binding of Nedd4-2 to ENaC. 4. Nedd4-2 is also phosphorylated by protein kinase B (Akt1). Both Sgk1 and Akt1 are part of the insulin signalling pathway that increases transepithelial Na(+) absorption by inhibiting Nedd4-2 and activating ENaC.
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Affiliation(s)
- Il-Ha Lee
- School of Medical Science, Faculty of Medicine, University of Sydney, Sydney, New South Wales, Australia
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Terada Y, Kuwana H, Kobayashi T, Okado T, Suzuki N, Yoshimoto T, Hirata Y, Sasaki S. Aldosterone-stimulated SGK1 activity mediates profibrotic signaling in the mesangium. J Am Soc Nephrol 2008; 19:298-309. [PMID: 18184857 DOI: 10.1681/asn.2007050531] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Several recent reports support the hypothesis that aldosterone contributes to the progression of renal injury. Mineralocorticoids increase the expression of serum- and glucocorticoid-inducible protein kinase 1 (SGK1), which is upregulated in several fibrotic diseases. It was hypothesized that SGK1 may mediate the effects of aldosterone on glomerular fibrosis and inflammation. In primary cultures of rat mesangial cells, aldosterone stimulated the expression, phosphorylation, and kinase activity of SGK1, as well as SGK1-dependent NF-kappaB activity. Furthermore, aldosterone augmented the promoter activity and protein expression of intercellular adhesion molecule-1 (ICAM-1), which modulates the inflammatory response, and the profibrotic cytokine connective tissue growth factor (CTGF) in an SGK1- and NF-kappaB-dependent manner. Similar to the in vitro results, uninephrectomized rats that were treated with aldosterone demonstrated increased glomerular expression of SGK1, ICAM-1, and CTGF proteins than untreated rats; these changes were accompanied by hypertension, glomerulosclerosis, and inflammation. In conclusion, these findings suggest that aldosterone stimulates ICAM-1 and CTGF transcription via the activation of SGK1 and NF-kappaB, effects that may contribute to the progression of aldosterone-induced mesangial fibrosis and inflammation.
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Affiliation(s)
- Yoshio Terada
- Department of Blood Purification and Nephrology, Tokyo Medical and Dental University, 5-45, Yushima 1-chome, Bunkyo-ku, Tokyo 113-8519, Japan.
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Viengchareun S, Le Menuet D, Martinerie L, Munier M, Pascual-Le Tallec L, Lombès M. The mineralocorticoid receptor: insights into its molecular and (patho)physiological biology. NUCLEAR RECEPTOR SIGNALING 2007; 5:e012. [PMID: 18174920 PMCID: PMC2121322 DOI: 10.1621/nrs.05012] [Citation(s) in RCA: 208] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/20/2007] [Accepted: 11/02/2007] [Indexed: 12/21/2022]
Abstract
The last decade has witnessed tremendous progress in the understanding of the mineralocorticoid receptor (MR), its molecular mechanism of action, and its implications for physiology and pathophysiology. After the initial cloning of MR, and identification of its gene structure and promoters, it now appears as a major actor in protein-protein interaction networks. The role of transcriptional coregulators and the determinants of mineralocorticoid selectivity have been elucidated. Targeted oncogenesis and transgenic mouse models have identified unexpected sites of MR expression and novel roles for MR in non-epithelial tissues. These experimental approaches have contributed to the generation of new cell lines for the characterization of aldosterone signaling pathways, and have also facilitated a better understanding of MR physiology in the heart, vasculature, brain and adipose tissues. This review describes the structure, molecular mechanism of action and transcriptional regulation mediated by MR, emphasizing the most recent developments at the cellular and molecular level. Finally, through insights obtained from mouse models and human disease, its role in physiology and pathophysiology will be reviewed. Future investigations of MR biology should lead to new therapeutic strategies, modulating cell-specific actions in the management of cardiovascular disease, neuroprotection, mineralocorticoid resistance, and metabolic disorders.
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Muto T, Ueda N, Opthof T, Ohkusa T, Nagata K, Suzuki S, Tsuji Y, Horiba M, Lee JK, Honjo H, Kamiya K, Kodama I, Yasui K. Aldosterone modulatesIfcurrent through gene expression in cultured neonatal rat ventricular myocytes. Am J Physiol Heart Circ Physiol 2007; 293:H2710-8. [PMID: 17644563 DOI: 10.1152/ajpheart.01399.2006] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Mineralocorticoid receptor (MR) antagonists decrease the incidence of sudden cardiac death in patients with heart failure, as has been reported in two clinical trials (Randomized Aldactone Evaluation Study and Eplerenone Post-Acute Myocardial Infarction Heart Failure Efficacy and Survival Study). Aldosterone has been shown to increase the propensity to arrhythmias by changing the expression or function of various ion channels. In this study, we investigate the effect of aldosterone on the expression of hyperpolarization-activated current ( If) channels in cultured neonatal rat ventricular myocytes, using the whole cell patch-clamp technique, real-time PCR, and Western blotting. Incubation with 10 nM aldosterone for 17–24 h significantly accelerates the rate of spontaneous beating by increasing diastolic depolarization. Ifcurrent elicited by hyperpolarization from −50 to −130 mV significantly increases aldosterone by 10 nM (by 1.9-fold). Exposure to aldosterone for 1.5 h increases hyperpolarization-activated cyclic nucleotide-gated (HCN) 2 mRNA by 26.3% and HCN4 mRNA by 47.2%, whereas HCN1 mRNA expression remains unaffected. Aldosterone (24-h incubation) increases the expression of HCN2 protein (by 60.0%) and HCN4 protein (by 84.8%), but not HCN1 protein. MR antagonists (1 μM eplerenone or 0.1 μM spironolactone) abolish the increase of Ifchannel expression (currents, mRNA, and protein levels) by 10 nM aldosterone. In contrast, 1 μM aldosterone downregulated Ifchannel gene expression. Glucocorticoid receptor antagonist (100 nM RU-38486) did not affect the increase of Ifcurrent by 10 nM aldosterone. These findings suggest that aldosterone in physiological concentrations upregulates Ifchannel gene expression by MR activation in cardiac myocytes and may increase excitability, which may have a potential proarrhythmic bearing under pathophysiological conditions.
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Affiliation(s)
- Takao Muto
- Research Institute of Environmental Medicine, Department of Bio-Information Analysis, Nagoya University, Nagoya 464-8601, Japan
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Abstract
Aldosterone concentrations are inappropriately high in many patients with hypertension, as well as in an increasing number of individuals with metabolic syndrome and sleep apnoea. A growing body of evidence suggests that aldosterone and/or activation of the MR (mineralocorticoid receptor) contributes to cardiovascular remodelling and renal injury in these conditions. In addition to causing sodium retention and increased blood pressure, MR activation induces oxidative stress, endothelial dysfunction, inflammation and subsequent fibrosis. The MR may be activated by aldosterone and cortisol or via transactivation by the AT(1) (angiotenin II type 1) receptor through a mechanism involving the EGFR (epidermal growth factor receptor) and MAPK (mitogen-activated protein kinase) pathway. In addition, aldosterone can generate rapid non-genomic effects in the heart and vasculature. MR antagonism reduces mortality in patients with CHF (congestive heart failure) and following myocardial infarction. MR antagonism improves endothelial function in patients with CHF, reduces circulating biomarkers of cardiac fibrosis in CHF or following myocardial infarction, reduces blood pressure in resistant hypertension and decreases albuminuria in hypertensive and diabetic patients. In contrast, whereas adrenalectomy improves glucose homoeostasis in hyperaldosteronism, MR antagonism may worsen glucose homoeostasis and impairs endothelial function in diabetes, suggesting a possible detrimental effect of aldosterone via non-genomic pathways.
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Affiliation(s)
- Annis M Marney
- Division of Clinical Pharmacology, Departments of Medicine and Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232-6602, USA
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Wang X, Luo C, Liu J, Zhang C, Wang Y, Zhu Z. Expression of serum and glucocorticoid-inducible kinase1 in diabetic rats and its modulation by fluvastatin. ACTA ACUST UNITED AC 2007; 25:651-4. [PMID: 16696316 DOI: 10.1007/bf02896161] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
The expression of serum and glucocorticoid-induced protein kinase in the renal cortex of diabetic rats was examined, and the function of signal transduction mediated by SGK1 in diabetic nephropathy and its modulatiqn by fluvastatin were also investigated. 24 male Wistar rats were randomly divided into normal control group (n = 8), diabetic nephropathy group (n = 8) and fluvastatin-treated diabetic nephropathy group (15 mg/kg/d, n = 8). The metabolic parameters were measured at the 8th week. The expression of transforming growth factor beta1 (TGF-beta1) and fibronectin (FN) was immunohistochemically examined. The expression of SGK1 was detected by RT-PCR and Western blot, and CTGF mRNA was assessed by RT-PCR. As compared to DN, blood glucose, 24-h urinary protein, Cer and kidney weight index were all decreased and the weight was increased obviously in group F. At the same time, mesangial cells and extracellular matrix proliferation were relieved significantly. The levels of cortex SGK1 mRNA and protein were up-regulated, and both TGF-beta1 and FN were down-regulated by fluvastatin. The mRNA of SGK1 was positively correlated with the CTGF, TGF-beta1 and FN. SGK1 expression is markedly up-regulated in the renal cortex of DN group and plays an important role in the development and progress of diabetic nephropathy by means of signal transduction. Fluvastatin suppressed the increased SGK1mRNA expression in renal cortex and postponed the development of diabetic nephropathy.
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Affiliation(s)
- Xuebin Wang
- Department of Nephrology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
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Sandberg MB, Riquier ADM, Pihakaski-Maunsbach K, McDonough AA, Maunsbach AB. ANG II provokes acute trafficking of distal tubule Na+-Cl(-) cotransporter to apical membrane. Am J Physiol Renal Physiol 2007; 293:F662-9. [PMID: 17507603 DOI: 10.1152/ajprenal.00064.2007] [Citation(s) in RCA: 126] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The distal convoluted tubule (DCT) Na+-Cl(-) cotransporter (NCC), the target of thiazide diuretics, is responsible for the reabsorption of 5-10% of filtered NaCl. The aim of this study was to test the hypothesis that acute infusion of the angiotensin-converting enzyme (ACE) inhibitor captopril (at 12 microg/min) for 20 min provokes trafficking of NCC from apical plasma membranes (APM) to subapical cytoplasmic vesicles (SCV), which is reversed by acute ANG II infusion (ANG II at 20 ng.kg(-1).min(-1) along with 12 microg/min captopril) for 20 min in male Sprague-Dawley rats (250-350 g). By immuno-electron microscopy using an anti-NCC (D. Ellison) 71.5 +/- SD 4.9% of the NCC gold labeling was associated with the APM in control, sham operated, and infused rats, while captopril infusion reduced NCC in APM to 54.9 +/- 6.9% (P < 0.001) and markedly increased immunogold labeling of SCV. Subsequent infusion of ANG II with captopril restored NCC immunogold labeling of APM to 72.4 +/- 4.2%, that is, 20% of the total NCC trafficked between APM and SCV. Likewise, on density gradients of cortex, captopril provoked redistribution of 27.3% of total NCC from low-density APM-enriched membranes to higher-density membranes and ANG II+captopril restored 20.3% of the NCC to APM-enriched fractions. Redistribution occurred independent of a change in NCC total abundance. In conclusion, this study demonstrates that ACE inhibition provokes acute trafficking of NCC out of the plasma membrane, which likely decreases DCT Na+ reabsorption, while ANG II provokes rapid trafficking of NCC from stores in subapical vesicles to the plasma membrane, which likely increases DCT Na+ reabsorption.
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Affiliation(s)
- Monica B Sandberg
- Department of Physiology and Biophysics, University of Southern California Keck School of Medicine, Los Angeles, California, USA
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Fernandes-Rosa FL, Antonini SRR. [Mineralocorticoid resistance: pseudohypoaldosteronism type 1]. ARQUIVOS BRASILEIROS DE ENDOCRINOLOGIA E METABOLOGIA 2007; 51:373-81. [PMID: 17546235 DOI: 10.1590/s0004-27302007000300004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2006] [Accepted: 10/22/2006] [Indexed: 05/15/2023]
Abstract
Pseudohypoaldosteronism type 1 (PHA1) is a rare genetic disease characterized by neonatal renal salt wasting, vomiting, dehydration and failure to thrive. Affected patients present hyponatremia, hyperkalemia, associated with high levels of plasma renin and aldosterone resulting from a renal or systemic resistance to aldosterone. The systemic form of PHA1 results in a severe phenotype, and high doses of salt supplementation are necessary. The symptoms are life-long recurrent. This form is associated with autosomal recessive transmission. Homozygous or compound heterozygous loss of function mutations in the genes coding for the epithelial sodium channel (ENaC) subunities are responsible for this disease. The renal form of PHA1 results in a mild phenotype. Low doses of salt supplementation are required and usually the symptoms remit at the end of the first year of life. Heterozygous loss-of-function mutations in the mineralocorticoid receptor (MR) gene are associated with the renal form of PHA1 in the majority of the affected families but sporadic cases have been reported. In this review the mechanisms of aldosterone action and its effects are discussed. Additionally, clinical and molecular findings of a Brazilian family with the renal form of PHA1 caused by a nonsense mutation (R947X) in the MR gene are presented.
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Affiliation(s)
- Fábio L Fernandes-Rosa
- Departamento de Puericultura e Pediatria, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, SP
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Huang DY, Boini KM, Osswald H, Friedrich B, Artunc F, Ullrich S, Rajamanickam J, Palmada M, Wulff P, Kuhl D, Vallon V, Lang F. Resistance of mice lacking the serum- and glucocorticoid-inducible kinase SGK1 against salt-sensitive hypertension induced by a high-fat diet. Am J Physiol Renal Physiol 2006; 291:F1264-73. [PMID: 17003223 DOI: 10.1152/ajprenal.00299.2005] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Mineralocorticoids enhance expression and insulin stimulates activity of the serum- and glucocorticoid-inducible kinase SGK1, which activates the renal epithelial Na+ channel (ENaC). Under a salt-deficient diet, SGK1 knockout mice ( sgk1−/−) excrete significantly more NaCl than their wild-type littermates ( sgk1 +/+) and become hypotensive. The present experiments explored whether SGK1 participates in the hypertensive effects of a high-fat diet and high-salt intake. Renal SGK1 protein abundance of sgk1 +/+ mice was significantly elevated after a high-fat diet. Under a control diet, fluid intake, blood pressure, urinary flow rate, and urinary Na+, K+, and Cl− excretion were similar in sgk1−/− and sgk1 +/+ mice. Under a standard diet, high salt (1% NaCl in the drinking water for 25 days) increased fluid intake, urinary flow rate, and urinary Na+, K+, and Cl− excretion similarly in sgk1−/− and sgk1 +/+ mice without significantly altering blood pressure. A high-fat diet alone (17 wk) did not significantly alter fluid intake, urinary flow rate, urinary Na+, K+, or Cl− excretion, or plasma aldosterone levels but increased plasma insulin, total cholesterol, triglyceride concentrations, and systolic blood pressure to the same extent in both genotypes. Additional salt intake (1% NaCl in the drinking water for 25 days) on top of a high-fat diet did not affect hyperinsulinemia or hyperlipidemia but increased fluid intake, urinary flow rate, and urinary NaCl excretion significantly more in sgk1−/− than in sgk1 +/+mice. Furthermore, in animals receiving a high-fat diet, additional salt intake increased blood pressure only in sgk1 +/+ mice (to 132 ± 3 mmHg) but not in sgk1−/− mice (120 ± 4 mmHg). Thus lack of SGK1 protects against the hypertensive effects of a combined high-fat/high-salt diet.
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Affiliation(s)
- Dan Yang Huang
- Department of Pharmacology, University of Tübingen, Gmelinstr. 5, D-72076 Tübingen, Germany
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Lang F, Böhmer C, Palmada M, Seebohm G, Strutz-Seebohm N, Vallon V. (Patho)physiological significance of the serum- and glucocorticoid-inducible kinase isoforms. Physiol Rev 2006; 86:1151-78. [PMID: 17015487 DOI: 10.1152/physrev.00050.2005] [Citation(s) in RCA: 515] [Impact Index Per Article: 28.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The serum- and glucocorticoid-inducible kinase-1 (SGK1) is ubiquitously expressed and under genomic control by cell stress (including cell shrinkage) and hormones (including gluco- and mineralocorticoids). Similar to its isoforms SGK2 and SGK3, SGK1 is activated by insulin and growth factors via phosphatidylinositol 3-kinase and the 3-phosphoinositide-dependent kinase PDK1. SGKs activate ion channels (e.g., ENaC, TRPV5, ROMK, Kv1.3, KCNE1/KCNQ1, GluR1, GluR6), carriers (e.g., NHE3, GLUT1, SGLT1, EAAT1-5), and the Na+-K+-ATPase. They regulate the activity of enzymes (e.g., glycogen synthase kinase-3, ubiquitin ligase Nedd4-2, phosphomannose mutase-2) and transcription factors (e.g., forkhead transcription factor FKHRL1, beta-catenin, nuclear factor kappaB). SGKs participate in the regulation of transport, hormone release, neuroexcitability, cell proliferation, and apoptosis. SGK1 contributes to Na+ retention and K+ elimination of the kidney, mineralocorticoid stimulation of salt appetite, glucocorticoid stimulation of intestinal Na+/H+ exchanger and nutrient transport, insulin-dependent salt sensitivity of blood pressure and salt sensitivity of peripheral glucose uptake, memory consolidation, and cardiac repolarization. A common ( approximately 5% prevalence) SGK1 gene variant is associated with increased blood pressure and body weight. SGK1 may thus contribute to metabolic syndrome. SGK1 may further participate in tumor growth, neurodegeneration, fibrosing disease, and the sequelae of ischemia. SGK3 is required for adequate hair growth and maintenance of intestinal nutrient transport and influences locomotive behavior. In conclusion, the SGKs cover a wide variety of physiological functions and may play an active role in a multitude of pathophysiological conditions. There is little doubt that further targets will be identified that are modulated by the SGK isoforms and that further SGK-dependent in vivo physiological functions and pathophysiological conditions will be defined.
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Affiliation(s)
- Florian Lang
- Department of Physiology, University of Tuebingen, Tuebingen, Germany.
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Wang D, Zhang H, Lang F, Yun CC. Acute activation of NHE3 by dexamethasone correlates with activation of SGK1 and requires a functional glucocorticoid receptor. Am J Physiol Cell Physiol 2006; 292:C396-404. [PMID: 16971495 PMCID: PMC2695591 DOI: 10.1152/ajpcell.00345.2006] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Glucocorticoids stimulate the intestinal absorption of Na(+) and water partly by regulation of the Na(+)/H(+) exchanger 3 (NHE3). Previous studies have shown both genomic and nongenomic regulation of NHE3 by glucocorticoids. Serum and glucocorticoid-inducible kinase 1 (SGK1) has been shown to be part of this cascade, where phosphorylation of NHE3 by SGK1 initiates the translocation of NHE3 to the cell surface. In the present work, we examined a series of changes in SGK1 and NHE3 induced by glucocorticoids using human colonic Caco-2 and opossum kidney cells. We found that dexamethasone rapidly stimulated SGK1 mRNAs, but a significant change in protein abundance was not detected. Instead, there was an increase in SGK1 kinase activity as early as at 2 h. An increase in NHE3 protein abundance was not detected until 12 h of dexamethasone exposure, although the transport activity was significantly stimulated at 4 h. These data demonstrate that the changes of SGK1 precede those of NHE3. Chronic regulation (24 h) of NHE3 was blocked completely by prevention of protein synthesis with cycloheximide or actinomycin D and by the glucocorticoid receptor blocker RU486. The acute effect of dexamethasone was similarly abrogated by RU486, but was insensitive to cycloheximide and actinomycin D. Similarly, the stimulation of SGK1 activity by dexamethasone was blocked by RU486 but not by actinomycin D. Together, these data show that the acute effect of glucocorticoids on NHE3 is mediated by a glucocorticoid receptor dependent mechanism that activates SGK1 in a nongenomic manner.
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Affiliation(s)
- Dongsheng Wang
- Department of Physiology, Emory University School of Medicine, 615 Michael Street, Atlanta, GA 30322, USA
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Rexhepaj R, Artunc F, Grahammer F, Nasir O, Sandu C, Friedrich B, Kuhl D, Lang F. SGK1 is not required for regulation of colonic ENaC activity. Pflugers Arch 2006; 453:97-105. [PMID: 16897044 DOI: 10.1007/s00424-006-0111-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2006] [Revised: 05/10/2006] [Accepted: 06/01/2006] [Indexed: 10/24/2022]
Abstract
The serum and glucocorticoid-inducible kinase SGK1 is known to be upregulated by mineralocorticoids and to enhance ENaC activity in several expression systems. Moreover, the amiloride-sensitive transepithelial potential difference in the collecting duct is lower in gene-targeted mice lacking SGK1 (sgk1 (-/-)) than in their wild-type littermates (sgk1 (+/+)). Accordingly, the ability of sgk1 (-/-) mice to decrease urinary sodium output during salt depletion is impaired. These observations highlight the importance of SGK1 in the stimulation of renal ENaC activity. In colonic epithelium, ENaC activity and, thus, transepithelial potential difference (V (te)) are similarly upregulated by mineralocorticoids. The present study thus explored V (te) and the apparent amiloride-sensitive equivalent short circuit current (I (amil)) in the colon from sgk1 (-/-) and sgk1 (+/+) mice before and after treatment with low salt diet, the glucocorticoid dexamethasone [DEXA, 10 mug/g body weight (BW)], or the mineralocorticoid deoxycorticosterone acetate (DOCA, 1.5 mg/day). Surprisingly, V (te) and I (amil) were both significantly (p<0.05) higher in sgk1 (-/-) than in sgk1 (+/+) untreated mice. A 7-day exposure to low salt diet increased V (te) and I (amil) in both genotypes, but did not abrogate the differences of V (te) and I (amil) between sgk1 (-/-) and sgk1 (+/+) mice. Plasma aldosterone levels were significantly higher in sgk1 (-/-) than in sgk1 (+/+) mice both under control conditions and under low salt diet, which may explain the enhanced V (te) in sgk1 (-/-) mice. Treatment with DEXA or DOCA both significantly increased V (te) and I (amil) in sgk1 (+/+) mice and tended to increase V (te) and I (amil) in sgk1 (-/-) mice. Under treatment with DEXA or DOCA, V (te) and I (amil) were similar in sgk1 (-/-) and sgk1 (+/+) mice. Fecal Na(+) excretion was similar in sgk1 (+/+) mice and in sgk1 (-/-) mice and was similarly decreased by low Na(+) diet in both genotypes. In conclusion, transepithelial potential and amiloride-sensitive short circuit current are enhanced in the colonic epithelium of SGK1-deficient mice. Thus, lack of SGK1 does not disrupt colonic ENaC activity and its regulation by salt depletion.
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Affiliation(s)
- Rexhep Rexhepaj
- Department of Physiology, University of Tübingen, Gmelinstr. 5, 72076 Tübingen, Germany
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