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Pavlov TS, Levchenko V, Ilatovskaya DV, Moreno C, Staruschenko A. Renal sodium transport in renin-deficient Dahl salt-sensitive rats. J Renin Angiotensin Aldosterone Syst 2016; 17:17/3/1470320316653858. [PMID: 27443990 PMCID: PMC5100984 DOI: 10.1177/1470320316653858] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2016] [Accepted: 05/15/2016] [Indexed: 01/01/2023] Open
Abstract
Objective: The Dahl salt-sensitive rat is a well-established model of salt-sensitive hypertension. The goal of this study was to assess the expression and activity of renal sodium channels and transporters in the renin-deficient salt-sensitive rat. Methods: Renin knockout (Ren−/−) rats created on the salt-sensitive rat background were used to investigate the role of renin in the regulation of ion transport in salt-sensitive hypertension. Western blotting and patch-clamp analyses were utilized to assess the expression level and activity of Na+ transporters. Results: It has been described previously that Ren−/− rats exhibit severe kidney underdevelopment, polyuria, and lower body weight and blood pressure compared to their wild-type littermates. Here we found that renin deficiency led to decreased expression of sodium-hydrogen antiporter (NHE3), the Na+/H+ exchanger involved in Na+ absorption in the proximal tubules, but did not affect the expression of Na-K-Cl cotransporter (NKCC2), the main transporter in the loop of Henle. In the distal nephron, the expression of sodium chloride cotransporter (NCC) was lower in Ren−/− rats. Single-channel patch clamp analysis detected decreased ENaC activity in Ren−/− rats which was mediated via changes in the channel open probability. Conclusion: These data illustrate that renin deficiency leads to significant dysregulation of ion transporters.
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Affiliation(s)
| | | | | | - Carol Moreno
- Department of Physiology, Medical College of Wisconsin, USA Cardiovascular and Metabolic Diseases, MedImmune, Cambridge, UK
| | - Alexander Staruschenko
- Department of Physiology, Medical College of Wisconsin, USA Cardiovascular Center, Medical College of Wisconsin, USA
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Elijovich F, Weinberger MH, Anderson CAM, Appel LJ, Bursztyn M, Cook NR, Dart RA, Newton-Cheh CH, Sacks FM, Laffer CL. Salt Sensitivity of Blood Pressure: A Scientific Statement From the American Heart Association. Hypertension 2016; 68:e7-e46. [PMID: 27443572 DOI: 10.1161/hyp.0000000000000047] [Citation(s) in RCA: 326] [Impact Index Per Article: 40.8] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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103
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Zhou J, Liu Y, Luo X, Shen R, Yang C, Yang T, Shi S. Identification and association of RAC1 gene polymorphisms with mRNA and protein expression levels of Rac1 in solid organ (kidney, liver, heart) transplant recipients. Mol Med Rep 2016; 14:1379-88. [PMID: 27279566 DOI: 10.3892/mmr.2016.5383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2015] [Accepted: 05/11/2016] [Indexed: 11/06/2022] Open
Abstract
The activation of Ras-related C3 botulinum toxin substrate 1 (Rac1) is critical in the renal, hepatic and cardiac diseases that lead to the requirement for transplantation, however, no investigations have been performed in Chinese populations to determine the association between RAC1 genotypes and the activation of Rac1. In the present study, 304 solid organ transplant recipients (SOTRs), consisting of 164 renal transplantations, 85 hepatic transplantations and 55 cardiac transplantations, and 332 Chinese healthy control subjects were recruited to investigate whether differences existed in the mRNA and protein expression levels of Rac1 in the different groups. Furthermore, the present study identified and investigated associations of the RAC1 (rs702482, rs10951982, rs702483 and rs6954996) genotypes with the mRNA expression levels of RAC1, and the protein expression levels of total Rac1 and active Rac1‑guanosine triphosphatase (GTP). It was identified that the healthy population had significantly higher levels of Rac1 and Rac1‑GTP, compared with the kidney, liver and heart transplantation populations (P<0.001 for all comparisons). Significant associations (P<0.05) were observed between the RAC1 genotypes and the expression levels of mRNA, Rac1 and Rac1‑GTP. However, the changes in the mRNA expression levels of RAC1 with genotypes were different from those of the proteins. The results of the present study represent the first, to the best of our knowledge, to report that Rac1 and Rac1‑GTP proteins can be downregulated in SOTRs, and that RAC1 genetic polymorphisms can potentially affect the mRNA expression of RAC1, and the protein expression of Rac1 and Rac1‑GTP. These results provide a foundation for further functional investigations to determine the biological and molecular functions of the RAC1 gene in SOTRs.
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Affiliation(s)
- Jiali Zhou
- Department of Pharmacy, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, P.R. China
| | - Yani Liu
- Department of Pharmacy, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, P.R. China
| | - Xiaomei Luo
- Department of Pharmacy, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, P.R. China
| | - Rufei Shen
- Department of Pharmacy, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, P.R. China
| | - Chunxiao Yang
- Department of Pharmacy, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, P.R. China
| | - Tingyu Yang
- Department of Pharmacy, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, P.R. China
| | - Shaojun Shi
- Department of Pharmacy, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, P.R. China
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Kawarazaki W, Fujita T. The Role of Aldosterone in Obesity-Related Hypertension. Am J Hypertens 2016; 29:415-23. [PMID: 26927805 PMCID: PMC4886496 DOI: 10.1093/ajh/hpw003] [Citation(s) in RCA: 98] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Revised: 12/15/2015] [Accepted: 01/04/2016] [Indexed: 12/11/2022] Open
Abstract
Obese subjects often have hypertension and related cardiovascular and renal diseases, and this has become a serious worldwide health problem. In obese subjects, impaired renal-pressure natriuresis causes sodium retention, leading to the development of salt-sensitive hypertension. Physical compression of the kidneys by visceral fat and activation of the sympathetic nervous system, renin-angiotensin systems (RAS), and aldosterone/mineralocorticoid receptor (MR) system are involved in this mechanism. Obese subjects often exhibit hyperaldosteronism, with increased salt sensitivity of blood pressure (BP). Adipose tissue excretes aldosterone-releasing factors, thereby stimulating aldosterone secretion independently of the systemic RAS, and aldosterone/MR activation plays a key role in the development of hypertension and organ damage in obesity. In obese subjects, both salt sensitivity of BP, enhanced by obesity-related metabolic disorders including aldosterone excess, and increased dietary sodium intake are closely related to the incidence of hypertension. Some salt sensitivity-related gene variants affect the risk of obesity, and together with salt intake, its combination is possibly associated with the development of hypertension in obese subjects. With high salt levels common in modern diets, salt restriction and weight control are undoubtedly important. However, not only MR blockade but also new diagnostic modalities and therapies targeting and modifying genes that are related to salt sensitivity, obesity, or RAS regulation are expected to prevent obesity and obesity-related hypertension.
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Affiliation(s)
- Wakako Kawarazaki
- Division of Clinical Epigenetics, Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan
| | - Toshiro Fujita
- Division of Clinical Epigenetics, Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan.
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Deletion of Rac1GTPase in the Myeloid Lineage Protects against Inflammation-Mediated Kidney Injury in Mice. PLoS One 2016; 11:e0150886. [PMID: 26939003 PMCID: PMC4777421 DOI: 10.1371/journal.pone.0150886] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Accepted: 02/19/2016] [Indexed: 12/16/2022] Open
Abstract
Macrophage-mediated inflammation has been implicated in various kidney diseases. We previously reported that Rac1, a Rho family small GTP-binding protein, was overactivated in several chronic kidney disease models, and that Rac1 inhibitors ameliorated renal injury, in part via inhibition of inflammation, but the detailed mechanisms have not been clarified. In the present study, we examined whether Rac1 in macrophages effects cytokine production and the inflammatory mechanisms contributing to kidney derangement. Myeloid-selective Rac1 flox control (M-Rac1 FC) and knockout (M-Rac1 KO) mice were generated using the cre-loxP system. Renal function under basal conditions did not differ between M-Rac1 FC and KO mice. Accordingly, lipopolysaccharide (LPS)-evoked kidney injury model was created. LPS elevated blood urea nitrogen and serum creatinine, enhanced expressions of kidney injury biomarkers, Kim-1 and Ngal, and promoted tubular injury in M-Rac1 FC mice. By contrast, deletion of myeloid Rac1 almost completely prevented the LPS-mediated renal impairment. LPS triggered a marked induction of macrophage-derived inflammatory cytokines, IL-6 and TNFα, in M-Rac1 FC mice, which was accompanied by Rac1 activation, stimulation of reduced nicotinamide-adenine dinucleotide phosphate (NADPH) oxidase, and reactive oxygen species overproduction. These changes were inhibited in M-Rac1 KO mice. LPS evoked F4/80-positive macrophages accumulation in the kidney, which was not affected by myeloid Rac1 deficiency. We further tested the role of Rac1 signaling in cytokine production using macrophage cell line, RAW264.7. Exposure to LPS increased IL-6 and TNFα mRNA expression. The LPS-driven cytokine induction was dose-dependently blocked by the Rac1 inhibitor EHT1864, NADPH oxidase inhibitor diphenyleneiodonium, and NF-κB inhibitor BAY11-7082. In conclusion, genetic ablation of Rac1 in the myeloid lineage protected against LPS-induced renal inflammation and injury, by suppressing macrophage-derived cytokines, IL-6 and TNFα, without blocking recruitment. Our data suggest that Rac1 in macrophage is a novel target for the treatment of kidney disease through inhibition of cytokine production.
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106
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Bai X, Dee R, Mangum KD, Mack CP, Taylor JM. RhoA signaling and blood pressure: The consequence of failing to “Tone it Down”. World J Hypertens 2016; 6:18-35. [DOI: 10.5494/wjh.v6.i1.18] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Revised: 11/24/2015] [Accepted: 01/22/2016] [Indexed: 02/06/2023] Open
Abstract
Uncontrolled high blood pressure is a major risk factor for heart attack, stroke, and kidney failure and contributes to an estimated 25% of deaths worldwide. Despite numerous treatment options, estimates project that reasonable blood pressure (BP) control is achieved in only about half of hypertensive patients. Improvements in the detection and management of hypertension will undoubtedly be accomplished through a better understanding of the complex etiology of this disease and a more comprehensive inventory of the genes and genetic variants that influence BP regulation. Recent studies (primarily in pre-clinical models) indicate that the small GTPase RhoA and its downstream target, Rho kinase, play an important role in regulating BP homeostasis. Herein, we summarize the underlying mechanisms and highlight signaling pathways and regulators that impart tight spatial-temporal control of RhoA activity. We also discuss known allelic variations in the RhoA pathway and consider how these polymorphisms may affect genetic risk for hypertension and its clinical manifestations. Finally, we summarize the current (albeit limited) clinical data on the efficacy of targeting the RhoA pathway in hypertensive patients.
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107
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Shibata S. Context-dependent mechanisms modulating aldosterone signaling in the kidney. Clin Exp Nephrol 2016; 20:663-670. [PMID: 26846783 DOI: 10.1007/s10157-016-1232-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Accepted: 01/08/2016] [Indexed: 12/16/2022]
Abstract
The aldosterone-mineralocorticoid receptor (MR) system serves as the major regulator of fluid homeostasis, and is an important drug target for the treatment of hypertension, heart failure, and chronic kidney disease. While the ligand aldosterone plays a central role in facilitating MR activity, recent studies have revealed that MR signaling is modulated through distinct mechanisms at the levels of the receptor and the downstream targets. Notably, phosphorylation of the ligand-binding domain in MR regulates the ability of the receptor to bind to ligand in renal intercalated cells, providing an additional layer of regulation that allows the cell-selective control of MR signaling. These mechanisms are involved in the context-dependent effects of aldosterone in the distal nephron. In this article, the recent progress in the understanding of mechanisms regulating the action of aldosterone is discussed, focusing on the connecting tubules and collecting duct in the kidney.
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Affiliation(s)
- Shigeru Shibata
- Division of Nephrology, Department of Internal Medicine, Teikyo University School of Medicine, 2-11-1 Kaga, Itabashi-ku, Tokyo, 173-8605, Japan. .,Division of Clinical Epigenetics, Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo, 153-8904, Japan.
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108
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Liu Y, Zhou J, Luo X, Yang C, Zhang Y, Shi S. Association of RAC1 Gene Polymorphisms with Primary End-Stage Renal Disease in Chinese Renal Recipients. PLoS One 2016; 11:e0148270. [PMID: 26841219 PMCID: PMC4739498 DOI: 10.1371/journal.pone.0148270] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2014] [Accepted: 01/15/2016] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND/OBJECTIVE RAC1 gene could influence susceptibility to renal failure by altering the activity and expression of Rac1, which is a member of the Rho family of small GTP-binding proteins. In clinical practice, renal transplantation provides the optimal treatment for people with end-stage renal disease (ESRD). The objective of this present study was to determine whether the RAC1 gene polymorphisms were associated with primary ESRD susceptibility in Chinese renal recipients. METHODS Six single nucleotide polymorphisms (SNPs) of RAC1 gene, including rs836488 T>C, rs702482 A>T, rs10951982 G>A, rs702483 A>G, rs6954996 G>A, and rs9374 G>A, were genotyped in 300 renal transplant recipients (cases) and 998 healthy Chinese subjects (controls) by using TaqMan SNP genotyping assay. Allele, genotype, and haplotype frequencies of the six SNPs were compared between cases and controls. Odds ratios (OR) and 95% confidence intervals (CI) were calculated in logistic regression models to evaluate the associations of the six SNPs with ESRD risk. RESULTS The genotype distributions for the six SNPs in controls were consistent with Hardy-Weinberg equilibrium (P > 0.05). Association analysis revealed that three SNPs were significantly associated with ESRD risk. Positive associations with ESRD risk were found for the rs836488, rs702482, and rs702483 in the co-dominant model (minor allele homozygotes versus major allele homozygotes); specifically, the frequencies of the minor allele homozygotes and the minor allele for the three SNPs were higher in the cases than in the controls. In addition, these three SNPs also had associations with increased ESRD risk under the additive model (P < 0.05), and positive associations were also found for the rs836488 in the dominant model (P < 0.05) and for the rs702483 in the recessive model (P < 0.05). All these associations were independent of confounding factors. The other three SNPs (rs10951982, rs6954996, and rs9374), in all comparison models, were not associated with ESRD risk (P > 0.05). In haplotype analysis, carriers with "C-T-G-G-G-G" haplotype had a significantly higher risk of ESRD compared with the most common haplotype "T-A-G-A-G-G" (P = 0.011, OR = 1.46, 95% CI = 1.09-1.94). CONCLUSION This study suggested that polymorphisms of RAC1 gene might influence the susceptibility to ESRD in Chinese Han population. Further studies are necessary to confirm our findings.
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Affiliation(s)
- Yani Liu
- Department of Pharmacy, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jiali Zhou
- Department of Pharmacy, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xiaomei Luo
- Department of Pharmacy, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Chunxiao Yang
- Department of Pharmacy, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yu Zhang
- Department of Pharmacy, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Shaojun Shi
- Department of Pharmacy, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- * E-mail:
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109
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Abstract
The impaired capacity of the kidney to excrete sodium plays an essential role in the development of hypertension. Adrenal corticosteroids control renal handling of sodium by regulating tubular sodium reabsorption in the distal nephron where both mineralocorticoid receptors (MR) and glucocorticoid receptors are expressed. In addition, cell type- and segment-specific expression of 11β-HSD2 and sodium transporters such as Na-Cl cotransporter (NCC), epithelial sodium channel (ENaC), and pendrin/Na(+)-driven Cl(-)/HCO3 (-) exchanger (NDCBE) builds a distinctive model of sodium transport in the aldosterone-sensitive distal nephron. Aberrant MR activation in the distal nephron triggers salt-sensitive hypertension and hypokalemia through inappropriate sodium reabsorption and potassium secretion. However, MR activity is not necessarily modulated by the ligand alone. Recently, several lines of evidence revealed alternative mechanisms that regulate the activity of MR in a ligand-independent manner or through ligand binding modulation. This review summarizes the disorders related to MR activation in individual tubular cells and highlights the renal mechanism of salt-sensitive hypertension and new approaches for the prevention and treatment of this disease.
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Affiliation(s)
- Nobuhiro Ayuzawa
- Department of Clinical Epigenetics, Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo, 153-8904, Japan
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Wan X, Lee MS, Zhou W. Dosage-dependent role of Rac1 in podocyte injury. Am J Physiol Renal Physiol 2016; 310:F777-F784. [PMID: 26792065 DOI: 10.1152/ajprenal.00381.2015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Accepted: 01/19/2016] [Indexed: 01/03/2023] Open
Abstract
Activation of small GTPase Rac1 in podocytes is associated with rodent models of kidney injury and familial nephrotic syndrome. Induced Rac1 activation in podocytes in transgenic mice results in rapid transient proteinuria and foot process effacement, but not glomerular sclerosis. Thus it remains an open question whether abnormal activation of Rac1 in podocytes is sufficient to cause permanent podocyte damage. Using a number of transgenic zebrafish models, we showed that moderate elevation of Rac1 activity in podocytes did not impair the glomerular filtration barrier but aggravated metronidazole-induced podocyte injury, while inhibition of Rac1 activity ameliorated metronidazole-induced podocyte injury. Furthermore, a further increase in Rac1 activity in podocytes was sufficient to cause proteinuria and foot process effacement, which resulted in edema and lethality in juvenile zebrafish. We also found that activation of Rac1 in podocytes significantly downregulated the expression of nephrin and podocin, suggesting an adverse effect of Rac1 on slit diaphragm protein expression. Taken together, our data have demonstrated a causal link between excessive Rac1 activity and podocyte injury in a dosage-dependent manner, and transgenic zebrafish of variable Rac1 activities in podocytes may serve as useful animal models for the study of Rac1-related podocytopathy.
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Affiliation(s)
- Xiaoyang Wan
- Department of Pediatrics and Communicable Diseases, University of Michigan, Ann Arbor, Michigan
| | - Mi-Sun Lee
- Department of Pediatrics and Communicable Diseases, University of Michigan, Ann Arbor, Michigan
| | - Weibin Zhou
- Department of Pediatrics and Communicable Diseases, University of Michigan, Ann Arbor, Michigan
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111
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Ayuzawa N, Nagase M, Ueda K, Nishimoto M, Kawarazaki W, Marumo T, Aiba A, Sakurai T, Shindo T, Fujita T. Rac1-Mediated Activation of Mineralocorticoid Receptor in Pressure Overload–Induced Cardiac Injury. Hypertension 2016; 67:99-106. [DOI: 10.1161/hypertensionaha.115.06054] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Accepted: 10/09/2015] [Indexed: 12/21/2022]
Affiliation(s)
- Nobuhiro Ayuzawa
- From the Division of Clinical Epigenetics, Research Center for Advanced Science and Technology (N.A., K.U., M. Nishimoto, W.K., T.M., T.F.), and Laboratory of Animal Resources, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine (A.A.), The University of Tokyo, Tokyo, Japan; Department of Anatomy and Life Structure, Faculty of Medicine, Juntendo University, Tokyo, Japan (M. Nagase); CREST, Japan Science and Technology Agency, Tokyo, Japan (T.M., T.F.); and Department of
| | - Miki Nagase
- From the Division of Clinical Epigenetics, Research Center for Advanced Science and Technology (N.A., K.U., M. Nishimoto, W.K., T.M., T.F.), and Laboratory of Animal Resources, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine (A.A.), The University of Tokyo, Tokyo, Japan; Department of Anatomy and Life Structure, Faculty of Medicine, Juntendo University, Tokyo, Japan (M. Nagase); CREST, Japan Science and Technology Agency, Tokyo, Japan (T.M., T.F.); and Department of
| | - Kohei Ueda
- From the Division of Clinical Epigenetics, Research Center for Advanced Science and Technology (N.A., K.U., M. Nishimoto, W.K., T.M., T.F.), and Laboratory of Animal Resources, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine (A.A.), The University of Tokyo, Tokyo, Japan; Department of Anatomy and Life Structure, Faculty of Medicine, Juntendo University, Tokyo, Japan (M. Nagase); CREST, Japan Science and Technology Agency, Tokyo, Japan (T.M., T.F.); and Department of
| | - Mitsuhiro Nishimoto
- From the Division of Clinical Epigenetics, Research Center for Advanced Science and Technology (N.A., K.U., M. Nishimoto, W.K., T.M., T.F.), and Laboratory of Animal Resources, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine (A.A.), The University of Tokyo, Tokyo, Japan; Department of Anatomy and Life Structure, Faculty of Medicine, Juntendo University, Tokyo, Japan (M. Nagase); CREST, Japan Science and Technology Agency, Tokyo, Japan (T.M., T.F.); and Department of
| | - Wakako Kawarazaki
- From the Division of Clinical Epigenetics, Research Center for Advanced Science and Technology (N.A., K.U., M. Nishimoto, W.K., T.M., T.F.), and Laboratory of Animal Resources, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine (A.A.), The University of Tokyo, Tokyo, Japan; Department of Anatomy and Life Structure, Faculty of Medicine, Juntendo University, Tokyo, Japan (M. Nagase); CREST, Japan Science and Technology Agency, Tokyo, Japan (T.M., T.F.); and Department of
| | - Takeshi Marumo
- From the Division of Clinical Epigenetics, Research Center for Advanced Science and Technology (N.A., K.U., M. Nishimoto, W.K., T.M., T.F.), and Laboratory of Animal Resources, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine (A.A.), The University of Tokyo, Tokyo, Japan; Department of Anatomy and Life Structure, Faculty of Medicine, Juntendo University, Tokyo, Japan (M. Nagase); CREST, Japan Science and Technology Agency, Tokyo, Japan (T.M., T.F.); and Department of
| | - Atsu Aiba
- From the Division of Clinical Epigenetics, Research Center for Advanced Science and Technology (N.A., K.U., M. Nishimoto, W.K., T.M., T.F.), and Laboratory of Animal Resources, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine (A.A.), The University of Tokyo, Tokyo, Japan; Department of Anatomy and Life Structure, Faculty of Medicine, Juntendo University, Tokyo, Japan (M. Nagase); CREST, Japan Science and Technology Agency, Tokyo, Japan (T.M., T.F.); and Department of
| | - Takayuki Sakurai
- From the Division of Clinical Epigenetics, Research Center for Advanced Science and Technology (N.A., K.U., M. Nishimoto, W.K., T.M., T.F.), and Laboratory of Animal Resources, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine (A.A.), The University of Tokyo, Tokyo, Japan; Department of Anatomy and Life Structure, Faculty of Medicine, Juntendo University, Tokyo, Japan (M. Nagase); CREST, Japan Science and Technology Agency, Tokyo, Japan (T.M., T.F.); and Department of
| | - Takayuki Shindo
- From the Division of Clinical Epigenetics, Research Center for Advanced Science and Technology (N.A., K.U., M. Nishimoto, W.K., T.M., T.F.), and Laboratory of Animal Resources, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine (A.A.), The University of Tokyo, Tokyo, Japan; Department of Anatomy and Life Structure, Faculty of Medicine, Juntendo University, Tokyo, Japan (M. Nagase); CREST, Japan Science and Technology Agency, Tokyo, Japan (T.M., T.F.); and Department of
| | - Toshiro Fujita
- From the Division of Clinical Epigenetics, Research Center for Advanced Science and Technology (N.A., K.U., M. Nishimoto, W.K., T.M., T.F.), and Laboratory of Animal Resources, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine (A.A.), The University of Tokyo, Tokyo, Japan; Department of Anatomy and Life Structure, Faculty of Medicine, Juntendo University, Tokyo, Japan (M. Nagase); CREST, Japan Science and Technology Agency, Tokyo, Japan (T.M., T.F.); and Department of
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112
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Takahashi S, Katada J, Daida H, Kitamura F, Yokoyama K. Effects of mineralocorticoid receptor antagonists in patients with hypertension and diabetes mellitus: a systematic review and meta-analysis. J Hum Hypertens 2015; 30:534-42. [PMID: 26674759 PMCID: PMC4981731 DOI: 10.1038/jhh.2015.119] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Revised: 10/31/2015] [Accepted: 11/05/2015] [Indexed: 12/24/2022]
Abstract
Blood pressure (BP) control is important to ameliorate cardiovascular events in patients with diabetes mellitus (DM). However, achieving the target BP with a single drug is often difficult. The objective of this study was to evaluate the antihypertensive effects of mineralocorticoid receptor antagonists (MRAs) as add-on therapy to renin–angiotensin system (RAS) inhibitor(s) in patients with hypertension and DM. Studies were searched through October 2014 in MEDLINE, Embase and the Cochrane Central Register of Controlled Trials. Randomized, controlled trials or prospective, observational studies regarding concomitant administration of MRA and RAS inhibitor(s) in patients with DM were included. Articles were excluded if the mean systolic BP (SBP) was <130 mm Hg before randomization for interventional studies or at baseline for prospective cohort studies. We identified nine eligible studies (486 patients): five randomized placebo-controlled trials; three randomized active drug-controlled trials; and one single-arm observational study. The mean differences in office SBP and diastolic BP (DBP) between the MRA and placebo groups were −9.4 (95% confidence interval (CI) −12.9 to −5.9) and −3.8 (95% CI, −5.5 to −2.2) mm Hg, respectively. Subgroup analysis results for study type, age, baseline office SBP and follow-up duration were similar to those of the main analysis. MRA mildly increased serum potassium (0.4 mEq l−1; 95% CI, 0.3–0.5 mEq l−1). A consistent reduction of albuminuria across these studies was also demonstrated. MRA further reduced SBP and DBP in patients with hypertension and DM already taking RAS inhibitors. Serum potassium levels should be monitored to prevent hyperkalemia.
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Affiliation(s)
- S Takahashi
- Department of Epidemiology and Environmental Health, Juntendo University Graduate School of Medicine, Tokyo, Japan.,Medical Affairs, Pfizer Japan Inc., Tokyo, Japan
| | - J Katada
- Medical Affairs, Pfizer Japan Inc., Tokyo, Japan
| | - H Daida
- Department of Cardiovascular Medicine, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - F Kitamura
- Department of Epidemiology and Environmental Health, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - K Yokoyama
- Department of Epidemiology and Environmental Health, Juntendo University Graduate School of Medicine, Tokyo, Japan
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Bernardi S, Toffoli B, Zennaro C, Bossi F, Losurdo P, Michelli A, Carretta R, Mulatero P, Fallo F, Veglio F, Fabris B. Aldosterone effects on glomerular structure and function. J Renin Angiotensin Aldosterone Syst 2015; 16:730-8. [PMID: 26283678 DOI: 10.1177/1470320315595568] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Accepted: 06/11/2015] [Indexed: 11/16/2022] Open
Abstract
OBJECTIVE Experimental evidence suggests that aldosterone directly contributes to organ damage by promoting cell growth, fibrosis, and inflammation. Based on these premises, this work aimed to assess the glomerular effects of aldosterone, alone and in combination with salt. METHODS After undergoing uninephrectomy, 75 rats were allocated to five groups: control, salt diet, aldosterone, aldosterone + salt diet, aldosterone + salt diet and eplerenone, and they were all studied for four weeks. We focused on glomerular structural, functional, and molecular changes, including slit diaphragm components, local renin-angiotensin system activation, as well as pro-oxidative and profibrotic changes. RESULTS Aldosterone significantly increased systolic blood pressure, led to glomerular hypertrophy, mesangial expansion, and it significantly increased the glomerular permeability to albumin and the albumin excretion rate, indicating the presence of glomerular damage. These effects were worsened by adding salt to aldosterone, while they were reduced by eplerenone. Aldosterone-induced glomerular damage was associated with glomerular angiotensin-converting enzyme (ACE) 2 downregulation, with ACE/ACE2 ratio increase, ANP decrease, as well as with glomerular pro-oxidative and profibrotic changes. CONCLUSIONS Aldosterone damages not only the structure but also the function of the glomerulus. ACE/ACE2 upregulation, ACE2 and ANP downregulation, and pro-oxidative and profibrotic changes are possible mechanisms accounting for aldosterone-induced glomerular injury.
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Affiliation(s)
- Stella Bernardi
- Department of Medical, Surgical and Health Sciences, University of Trieste, Cattinara Teaching Hospital, Italy
| | - Barbara Toffoli
- Department of Medical, Surgical and Health Sciences, University of Trieste, Cattinara Teaching Hospital, Italy Centre for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, Switzerland
| | - Cristina Zennaro
- Department of Medical, Surgical and Health Sciences, University of Trieste, Cattinara Teaching Hospital, Italy
| | - Fleur Bossi
- Department of Medical, Surgical and Health Sciences, University of Trieste, Cattinara Teaching Hospital, Italy
| | - Pasquale Losurdo
- Department of Medical, Surgical and Health Sciences, University of Trieste, Cattinara Teaching Hospital, Italy
| | - Andrea Michelli
- Department of Medical, Surgical and Health Sciences, University of Trieste, Cattinara Teaching Hospital, Italy
| | - Renzo Carretta
- Department of Medical, Surgical and Health Sciences, University of Trieste, Cattinara Teaching Hospital, Italy
| | - Paolo Mulatero
- Division of Internal Medicine and Hypertension, University of Torino, Italy
| | - Francesco Fallo
- Department of Medical and Surgical Sciences, University of Padova, Italy
| | - Franco Veglio
- Division of Internal Medicine and Hypertension, University of Torino, Italy
| | - Bruno Fabris
- Department of Medical, Surgical and Health Sciences, University of Trieste, Cattinara Teaching Hospital, Italy
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Suehiro T, Tsuruya K, Ikeda H, Toyonaga J, Yamada S, Noguchi H, Tokumoto M, Kitazono T. Systemic Aldosterone, But Not Angiotensin II, Plays a Pivotal Role in the Pathogenesis of Renal Injury in Chronic Nitric Oxide-Deficient Male Rats. Endocrinology 2015; 156:2657-66. [PMID: 25872005 DOI: 10.1210/en.2014-1369] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Chronic inhibition of nitric oxide synthase by N(ω)-nitro-L-arginine methyl ester (L-NAME) causes progressive renal injury and systemic hypertension. Angiotensin II (Ang II) has been conventionally regarded as one of the primary causes of renal injury. We reported previously that such renal injury was almost completely suppressed by both an Ang II type I receptor blocker and an aldosterone antagonist. The aldosterone antagonist also inhibited the systemic Ang II elevation. Therefore, it remains to be elucidated whether Ang II or aldosterone directly affects the development of such renal injury. In the present study, we investigated the role of aldosterone in the pathogenesis of renal injury induced by L-NAME-mediated chronic nitric oxide synthase inhibition in male Wistar rats (aged 10 wk). Serial analyses demonstrated that the renal injury and inflammation in L-NAME-treated rats was associated with elevation of both Ang II and aldosterone. To investigate the direct effect of aldosterone on the renal injury, we conducted adrenalectomy (ADX) and aldosterone supplementation in L-NAME-treated rats. In ADX rats, aldosterone was undetectable, and renal injury and inflammation were almost completely prevented by ADX, although systemic and local Ang II and blood pressure were still elevated. Aldosterone supplementation reversed the beneficial effect of ADX. The present study indicates that aldosterone rather than Ang II plays a central and direct role in the pathogenesis of renal injury by L-NAME through inflammation, independent of its systemic hemodynamic effects.
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Affiliation(s)
- Takaichi Suehiro
- Department of Medicine and Clinical Science (T.S., K.T., H.I., J.T., S.Y., H.N., T.K.), Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan; Department of Integrated Therapy for Chronic Kidney Disease (K.T.), Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan; and Department of Internal Medicine (S.Y., M.T.), Fukuoka Dental College, Fukuoka 814-0175, Japan
| | - Kazuhiko Tsuruya
- Department of Medicine and Clinical Science (T.S., K.T., H.I., J.T., S.Y., H.N., T.K.), Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan; Department of Integrated Therapy for Chronic Kidney Disease (K.T.), Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan; and Department of Internal Medicine (S.Y., M.T.), Fukuoka Dental College, Fukuoka 814-0175, Japan
| | - Hirofumi Ikeda
- Department of Medicine and Clinical Science (T.S., K.T., H.I., J.T., S.Y., H.N., T.K.), Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan; Department of Integrated Therapy for Chronic Kidney Disease (K.T.), Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan; and Department of Internal Medicine (S.Y., M.T.), Fukuoka Dental College, Fukuoka 814-0175, Japan
| | - Jiro Toyonaga
- Department of Medicine and Clinical Science (T.S., K.T., H.I., J.T., S.Y., H.N., T.K.), Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan; Department of Integrated Therapy for Chronic Kidney Disease (K.T.), Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan; and Department of Internal Medicine (S.Y., M.T.), Fukuoka Dental College, Fukuoka 814-0175, Japan
| | - Shunsuke Yamada
- Department of Medicine and Clinical Science (T.S., K.T., H.I., J.T., S.Y., H.N., T.K.), Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan; Department of Integrated Therapy for Chronic Kidney Disease (K.T.), Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan; and Department of Internal Medicine (S.Y., M.T.), Fukuoka Dental College, Fukuoka 814-0175, Japan
| | - Hideko Noguchi
- Department of Medicine and Clinical Science (T.S., K.T., H.I., J.T., S.Y., H.N., T.K.), Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan; Department of Integrated Therapy for Chronic Kidney Disease (K.T.), Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan; and Department of Internal Medicine (S.Y., M.T.), Fukuoka Dental College, Fukuoka 814-0175, Japan
| | - Masanori Tokumoto
- Department of Medicine and Clinical Science (T.S., K.T., H.I., J.T., S.Y., H.N., T.K.), Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan; Department of Integrated Therapy for Chronic Kidney Disease (K.T.), Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan; and Department of Internal Medicine (S.Y., M.T.), Fukuoka Dental College, Fukuoka 814-0175, Japan
| | - Takanari Kitazono
- Department of Medicine and Clinical Science (T.S., K.T., H.I., J.T., S.Y., H.N., T.K.), Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan; Department of Integrated Therapy for Chronic Kidney Disease (K.T.), Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582, Japan; and Department of Internal Medicine (S.Y., M.T.), Fukuoka Dental College, Fukuoka 814-0175, Japan
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Shimizu Y, Kadota K, Koyamatsu J, Yamanashi H, Nagayoshi M, Noda M, Nishimura T, Tayama J, Nagata Y, Maeda T. Salt intake and mental distress among rural community-dwelling Japanese men. J Physiol Anthropol 2015; 34:26. [PMID: 26109460 PMCID: PMC4480897 DOI: 10.1186/s40101-015-0064-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Accepted: 06/08/2015] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND Activated mineralocorticoid receptors influence the association between daily salt intake and blood pressure. A relatively low mineralocorticoid receptor function is reported to be a risk for mental distress such as depression. Since mental distress is also a known risk for hypertension and cardiovascular disease, understanding of the association between estimated daily salt intake and mental distress contributing to hypertension is important for risk estimation for cardiovascular disease. However, no single study has reported this association. METHODS We conducted a cross-sectional study of 1014 Japanese men undergoing general health check-ups. Mental distress was diagnosed as a Kessler 6 scale score ≥5. We also classified mental distress by levels of hypertension. Estimated daily salt intake was calculated from a causal urine specimen. RESULTS Independent from classical cardiovascular risk factors and thyroid disease, we found a significant inverse association between estimated daily salt intake and mental distress. When we analyzed for mental distress and hypertension, we also found a significant association. With the reference group being the lowest tertiles of estimated daily salt intake, the multivariable odds ratios (ORs) of mental distress and mental distress with hypertension for the highest tertiles were 0.50 (0.29-0.88) and 0.46 (0.22-0.96). CONCLUSIONS Lower estimated daily salt intake is a significant risk of mental distress for rural community-dwelling Japanese men. Since depression is reported to be associated with cardiovascular disease, risk estimation for the lower intake of salt on mental distress, especially for mental distress with hypertension, may become an important tool to prevent cardiovascular disease.
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Affiliation(s)
- Yuji Shimizu
- Department of Community Medicine, Nagasaki University Graduate School of Biomedical Science, Nagasaki, Japan.
| | - Koichiro Kadota
- Department of Community Medicine, Nagasaki University Graduate School of Biomedical Science, Nagasaki, Japan.
| | - Jun Koyamatsu
- Department of Community Medicine, Nagasaki University Graduate School of Biomedical Science, Nagasaki, Japan.
| | - Hirotomo Yamanashi
- Department of Island and Community Medicine, Nagasaki University Graduate School of Biomedical Science, Nagasaki, Japan.
| | - Mako Nagayoshi
- Department of Community Medicine, Nagasaki University Graduate School of Biomedical Science, Nagasaki, Japan.
| | - Miki Noda
- Department of Community Medicine, Nagasaki University Graduate School of Biomedical Science, Nagasaki, Japan.
| | - Takayuki Nishimura
- Department of Public Health, Nagasaki University Graduate School of Biomedical Science, Nagasaki, Japan.
| | - Jun Tayama
- Graduate School of Education, Nagasaki University, Nagasaki, Japan. .,Center for Health and Community Medicine, Nagasaki University, Nagasaki, Japan.
| | - Yasuhiro Nagata
- Center for Comprehensive Community Care Education, Nagasaki University Graduate School of Biomedical Science, Nagasaki, Japan.
| | - Takahiro Maeda
- Department of Community Medicine, Nagasaki University Graduate School of Biomedical Science, Nagasaki, Japan. .,Department of Island and Community Medicine, Nagasaki University Graduate School of Biomedical Science, Nagasaki, Japan.
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Tapia-Castillo A, Carvajal CA, Campino C, Hill C, Allende F, Vecchiola A, Carrasco C, Bancalari R, Valdivia C, Lagos C, Martinez-Aguayo A, Garcia H, Aglony M, Baudrand RF, Kalergis AM, Michea LF, Riedel CA, Fardella CE. The Expression of RAC1 and Mineralocorticoid Pathway-Dependent Genes are Associated With Different Responses to Salt Intake. Am J Hypertens 2015; 28:722-8. [PMID: 25430696 DOI: 10.1093/ajh/hpu224] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2014] [Accepted: 10/13/2014] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND Rac1 upregulation has been implicated in salt-sensitive hypertension as a modulator of mineralocorticoid receptor (MR) activity. Rac1 could affect the expression of oxidative stress markers, such as hemoxigenase-1 (HO-1) or nuclear factor-B (NF-κB), and the expression of neutrophil gelatinase-associated lipocalin (NGAL), a cytokine upregulated upon MR activation. AIM We evaluated RAC1 expression in relation of high salt intake and association with MR, NGAL, HO-1, and NF-κB expression, mineralo- and glucocorticoids levels, and inflammatory parameters. SUBJECTS AND METHODS We studied 147 adult subjects. A food survey identified the dietary sodium (Na) intake. RAC1 expression was considered high or low according to the value found in normotensive subjects with low salt intake. We determined the gene expression of RAC1, MR, NGAL, HO-1, NF-κB, and 18S, isolated from peripheral leukocytes. We measured aldosterone, cortisol, sodium, potassium excretion, metalloproteinase (MMP9 y MMP2), and C-reactive protein. RESULTS We identified 126 subjects with high Na-intake, 18 subjects had high, and 108 low-RAC1 expression. The subjects with high-RAC1 expression showed a significant increase in MR (P = 0.0002), NGAL (P < 0.0001) HO-1 (P = 0.0004), and NF-κB (P < 0.0001) gene expression. We demonstrated an association between RAC1 expression and MR (R sp 0.64; P < 0.0001), NGAL (R sp 0.48; P < 0.0001), HO-1 (R sp 0.53; P < 0.0001), and NF-κB (R sp0.52; P < 0.0001). We did not identify any association between RAC1 and clinical or biochemical variables. CONCLUSIONS RAC1 expression was associated with an increase in MR, NGAL, NF-κB, and HO-1 expression, suggesting that RAC1 could be a mediator of cardiovascular damage induced by sodium, and may also useful to identify subjects with different responses to salt intake.
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Affiliation(s)
| | - Cristian A Carvajal
- Endocrinology, Escuela de Medicina, Pontificia Universidad Catolica de Chile, Santiago, Chile; Millenium Institute in Immunology and Immunotherapy, Santiago, Chile
| | - Carmen Campino
- Endocrinology, Escuela de Medicina, Pontificia Universidad Catolica de Chile, Santiago, Chile; Millenium Institute in Immunology and Immunotherapy, Santiago, Chile
| | - Caroline Hill
- Endocrinology, Escuela de Medicina, Pontificia Universidad Catolica de Chile, Santiago, Chile
| | - Fidel Allende
- Servicios de Laboratorios Clinicos, Pontificia Universidad Catolica de Chile, Santiago, Chile
| | - Andrea Vecchiola
- Endocrinology, Escuela de Medicina, Pontificia Universidad Catolica de Chile, Santiago, Chile; Millenium Institute in Immunology and Immunotherapy, Santiago, Chile
| | - Carmen Carrasco
- Endocrinology, Escuela de Medicina, Pontificia Universidad Catolica de Chile, Santiago, Chile
| | - Rodrigo Bancalari
- Pediatrics, Escuela de Medicina, Pontificia Universidad Catolica de Chile, Santiago, Chile
| | - Carolina Valdivia
- Endocrinology, Escuela de Medicina, Pontificia Universidad Catolica de Chile, Santiago, Chile
| | - Carlos Lagos
- Endocrinology, Escuela de Medicina, Pontificia Universidad Catolica de Chile, Santiago, Chile
| | | | - Hernan Garcia
- Pediatrics, Escuela de Medicina, Pontificia Universidad Catolica de Chile, Santiago, Chile
| | - Marlene Aglony
- Pediatrics, Escuela de Medicina, Pontificia Universidad Catolica de Chile, Santiago, Chile
| | - Rene F Baudrand
- Endocrinology, Escuela de Medicina, Pontificia Universidad Catolica de Chile, Santiago, Chile
| | - Alexis M Kalergis
- Millenium Institute in Immunology and Immunotherapy, Santiago, Chile; Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas. Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Luis F Michea
- Millenium Institute in Immunology and Immunotherapy, Santiago, Chile; Laboratory of Integrative Physiology, ICBM, Universidad de Chile, Santiago, Chile
| | - Claudia A Riedel
- Millenium Institute in Immunology and Immunotherapy, Santiago, Chile; Departamento de Ciencias Biológicas, Facultad Ciencias Biológicas y Facultad de Medicina Universidad Andrés Bello, Santiago, Chile
| | - Carlos E Fardella
- Endocrinology, Escuela de Medicina, Pontificia Universidad Catolica de Chile, Santiago, Chile; Millenium Institute in Immunology and Immunotherapy, Santiago, Chile;
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Ray EC, Rondon-Berrios H, Boyd CR, Kleyman TR. Sodium retention and volume expansion in nephrotic syndrome: implications for hypertension. Adv Chronic Kidney Dis 2015; 22:179-84. [PMID: 25908466 PMCID: PMC4409655 DOI: 10.1053/j.ackd.2014.11.006] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Revised: 11/11/2014] [Accepted: 11/20/2014] [Indexed: 01/09/2023]
Abstract
Sodium retention is a major clinical feature of nephrotic syndrome. The mechanisms responsible for sodium retention in this setting have been a subject of debate for years. Excessive sodium retention occurs in some individuals with nephrotic syndrome in the absence of activation of the renin-angiotensin-aldosterone system, suggesting an intrinsic defect in sodium excretion by the kidney. Recent studies have provided new insights regarding mechanisms by which sodium transporters are activated by factors present in nephrotic urine. These mechanisms likely have a role in the development of hypertension in nephrotic syndrome, where hypertension may be difficult to control, and provide new therapeutic options for the management of blood pressure and edema in the setting of nephrotic syndrome.
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Affiliation(s)
- Evan C Ray
- Renal Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, PA; and Department of Cell Biology, University of Pittsburgh, Pittsburgh, PA
| | - Helbert Rondon-Berrios
- Renal Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, PA; and Department of Cell Biology, University of Pittsburgh, Pittsburgh, PA.
| | - Cary R Boyd
- Renal Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, PA; and Department of Cell Biology, University of Pittsburgh, Pittsburgh, PA
| | - Thomas R Kleyman
- Renal Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, PA; and Department of Cell Biology, University of Pittsburgh, Pittsburgh, PA
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118
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The necessity and effectiveness of mineralocorticoid receptor antagonist in the treatment of diabetic nephropathy. Hypertens Res 2015; 38:367-74. [PMID: 25762415 DOI: 10.1038/hr.2015.19] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Revised: 12/06/2014] [Accepted: 12/31/2014] [Indexed: 02/06/2023]
Abstract
Diabetes mellitus is a major cause of chronic kidney disease (CKD), and diabetic nephropathy is the most common primary disease necessitating dialysis treatment in the world including Japan. Major guidelines for treatment of hypertension in Japan, the United States and Europe recommend the use of angiotensin-converting enzyme inhibitors and angiotensin-receptor blockers, which suppress the renin-angiotensin system (RAS), as the antihypertensive drugs of first choice in patients with coexisting diabetes. However, even with the administration of RAS inhibitors, failure to achieve adequate anti-albuminuric, renoprotective effects and a reduction in cardiovascular events has also been reported. Inadequate blockade of aldosterone may be one of the reasons why long-term administration of RAS inhibitors may not be sufficiently effective in patients with diabetic nephropathy. This review focuses on treatment in diabetic nephropathy and discusses the significance of aldosterone blockade. In pre-nephropathy without overt nephropathy, a mineralocorticoid receptor antagonist can be used to enhance the blood pressure-lowering effects of RAS inhibitors, improve insulin resistance and prevent clinical progression of nephropathy. In CKD categories A2 and A3, the addition of a mineralocorticoid receptor antagonist to an RAS inhibitor can help to maintain 'long-term' antiproteinuric and anti-albuminuric effects. However, in category G3a and higher, sufficient attention must be paid to hyperkalemia. Mineralocorticoid receptor antagonists are not currently recommended as standard treatment in diabetic nephropathy. However, many studies have shown promise of better renoprotective effects if mineralocorticoid receptor antagonists are appropriately used.
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119
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Schwenk MH, Hirsch JS, Bomback AS. Aldosterone blockade in CKD: emphasis on pharmacology. Adv Chronic Kidney Dis 2015; 22:123-32. [PMID: 25704349 DOI: 10.1053/j.ackd.2014.08.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Accepted: 08/11/2014] [Indexed: 12/16/2022]
Abstract
Besides its epithelial effect on sodium retention and potassium excretion in the distal tubule, aldosterone promotes inflammation and fibrosis in the heart, kidneys, and blood vessels. As glomerular filtration rate falls, aldosterone is inappropriately elevated relative to extracellular fluid expansion. In addition, studies in CKD patients on angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, and/or direct renin inhibitors have shown that aldosterone levels paradoxically rise in approximately 30% to 40% of patients on these renin-angiotensin system-blocking drugs. Hence, there is interest in using mineralocorticoid receptor blockers that directly target the inflammatory and fibrotic effects of aldosterone in CKD patients. This interest, however, is tempered by a number of unresolved issues, including the safety of using such drugs in advanced CKD and ESRD populations, and the potential for differences in drug efficacy according to race and ethnicity of patient populations. A better understanding of mineralocorticoid receptor blocker pharmacology should help inform future research directions and clinical practice decisions as to how best to use these agents in CKD.
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Nishimoto M, Fujita T. Renal mechanisms of salt-sensitive hypertension: contribution of two steroid receptor-associated pathways. Am J Physiol Renal Physiol 2015; 308:F377-87. [DOI: 10.1152/ajprenal.00477.2013] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Although salt is a major environmental factor in the development of hypertension, the degree of salt sensitivity varies widely among individuals. The mechanisms responsible for this variation remain to be elucidated. Recent studies have revealed the involvement of two important signaling pathways in renal tubules that play key roles in electrolyte balance and the maintenance of normal blood pressure: the β2-adrenergic stimulant-glucocorticoid receptor (GR)-with-no-lysine kinase (WNK)4-Na+-Cl− cotransporter pathway, which is active in distal convoluted tubule (DCT)1, and the Ras-related C3 botulinum toxin substrate (Rac)1-mineralocorticoid receptor (MR) pathway, which is active in DCT2, connecting tubules, and collecting ducts. β2-Adrenergic stimulation due to increased renal sympathetic activity in obesity- and salt-induced hypertension suppresses histone deacetylase 8 activity via cAMP/PKA signaling, increasing the accessibility of GRs to the negative GR response element in the WNK4 promoter. This results in the suppression of WNK4 transcription followed by the activation of Na+-Cl− cotransporters in the DCT and elevated Na+ retention and blood pressure upon salt loading. Rac1 activates MRs, even in the absence of ligand binding, with this activity increased in the presence of ligand. In salt-sensitive animals, Rac1 activation due to salt loading activates MRs in DCT2, connecting tubules, and collecting ducts. Thus, GRs and MRs are independently involved in two pathways responsible for renal Na+ handling and salt-sensitive hypertension. These findings suggest novel therapeutic targets and may lead to the development of diagnostic tools to determine salt sensitivity in hypertensive patients.
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Affiliation(s)
- Mitsuhiro Nishimoto
- Division of Clinical Epigenetics, Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan
| | - Toshiro Fujita
- Division of Clinical Epigenetics, Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan
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Sawada H, Naito Y, Oboshi M, Iwasaku T, Okuhara Y, Morisawa D, Eguchi A, Hirotani S, Masuyama T. Iron restriction inhibits renal injury in aldosterone/salt-induced hypertensive mice. Hypertens Res 2015; 38:317-22. [PMID: 25693852 DOI: 10.1038/hr.2015.13] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Revised: 12/03/2014] [Accepted: 12/31/2014] [Indexed: 01/28/2023]
Abstract
Excess iron is associated with the pathogenesis of several renal diseases. Aldosterone is reported to have deleterious effects on the kidney, but there have been no reports of the role of iron in aldosterone/salt-induced renal injury. Therefore, we investigated the effects of dietary iron restriction on the development of hypertension and renal injury in aldosterone/salt-induced hypertensive mice. Ten-week-old male C57BL/6J mice were uninephrectomized and infused with aldosterone for four weeks. These were divided into two groups: one fed a high-salt diet (Aldo) and the other fed a high-salt with iron-restricted diet (Aldo-IR). Vehicle-infused mice without a uninephrectomy were also divided into two groups: one fed a normal diet (control) and the other fed an iron-restricted diet (IR) for 4 weeks. As compared with control and IR mice, Aldo mice showed an increase in both systolic blood pressure and urinary albumin/creatinine ratio, but these increases were reduced in the Aldo-IR group. In addition, renal histology revealed that Aldo mice exhibited glomerulosclerosis and tubulointerstitial fibrosis, whereas these changes were attenuated in Aldo-IR mice. Expression of intracellular iron transport protein transferrin receptor 1 was increased in the renal tubules of Aldo mice compared with control mice. Dietary iron restriction attenuated the development of hypertension and renal injury in aldosterone/salt-induced hypertensive mice.
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Affiliation(s)
- Hisashi Sawada
- Cardiovascular Division, Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Japan
| | - Yoshiro Naito
- Cardiovascular Division, Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Japan
| | - Makiko Oboshi
- Cardiovascular Division, Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Japan
| | - Toshihiro Iwasaku
- Cardiovascular Division, Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Japan
| | - Yoshitaka Okuhara
- Cardiovascular Division, Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Japan
| | - Daisuke Morisawa
- Cardiovascular Division, Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Japan
| | - Akiyo Eguchi
- Cardiovascular Division, Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Japan
| | - Shinichi Hirotani
- Cardiovascular Division, Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Japan
| | - Tohru Masuyama
- Cardiovascular Division, Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Japan
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Nagase M. Recent topics on podocytes and aldosterone. J Ren Nutr 2014; 25:201-4. [PMID: 25499230 DOI: 10.1053/j.jrn.2014.10.016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2014] [Accepted: 10/29/2014] [Indexed: 11/11/2022] Open
Abstract
Podocyte injury is a major cause of proteinuria, a core component of chronic kidney disease. We reported that podocyte impairment underlied the early glomerulopathy in animal models of lifestyle-related diseases, such as hypertension and metabolic syndrome. Accumulating evidence suggests that overactivation of the aldosterone-mineralocorticoid receptor (MR) system has harmful effects on podocytes. We found that MR signaling was enhanced in such lifestyle-related diseases with podocyte injury and proteinuria, which were ameliorated by MR antagonist. Subsequent studies revealed that plasma aldosterone concentrations are not always increased in proteinuric conditions with renal MR activation, and the mechanisms of MR overactivation remained elusive. We recently identified a novel mechanism of Rac1-mediated podocyte impairment using RhoGDIα knockout mice; Rac1 potentiates the activity of MR in a ligand-independent manner, thereby accelerating podocyte injury. We demonstrated that the Rac1-MR pathway contributes to the ligand-independent aberrant MR activation in salt-sensitive hypertension and renal injury models. The importance of the RhoGDIα-Rac1-MR pathway in human glomerular disease is underscored by the findings that mutations in RhoGDIαgene cause nephrotic syndrome. Our results provide evidence that the Rac1-MR signal cascade as a novel therapeutic target for chronic kidney disease.
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Affiliation(s)
- Miki Nagase
- Department of Anatomy and Life Structure, School of Medicine, Juntendo University, Bunkyo-ku, Tokyo, Japan.
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Ando K, Ohtsu H, Uchida S, Kaname S, Arakawa Y, Fujita T. Anti-albuminuric effect of the aldosterone blocker eplerenone in non-diabetic hypertensive patients with albuminuria: a double-blind, randomised, placebo-controlled trial. Lancet Diabetes Endocrinol 2014; 2:944-53. [PMID: 25466242 DOI: 10.1016/s2213-8587(14)70194-9] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
BACKGROUND Renin-angiotensin system inhibitors have renoprotective effects in patients with chronic kidney disease, but most patients treated with these drugs have residual urinary albumin excretion. Some small clinical studies show that mineralocorticoid receptor blockade reduces albuminuria. Our study aimed to examine the beneficial effects of addition of a selective aldosterone antagonist, eplerenone, to renin-angiotensin system inhibitors in hypertensive patients with non-diabetic chronic kidney disease. METHODS In this double-blind, randomised, placebo-controlled trial, we enrolled hypertensive patients, aged 20–79 years, with albuminuria (urinary albumin-to-creatinine ratio [UACR] in the first morning void urine of 30–599 mg/g), an estimated glomerular filtration rate of 50 mL/min per 1·73 m2 or more, and who had received an angiotensin-converting enzyme inhibitor, an angiotensin receptor blocker, or both, for at least 8 weeks. Participants were from 59 clinics and hospitals in Japan. Eligible patients were randomly assigned (1:1), stratified by baseline characteristics, to either low-dose eplerenone (50 mg/day) or placebo, with continuation of standard antihypertensive treatment to attain therapeutic goals (<130/80 mm Hg) for 52 weeks. We assessed efficacy in all patients who received allocated treatment, provided a baseline and post-treatment urine sample, and remained in follow-up. We assessed safety in all patients who received allocated treatment. The primary efficacy measure was percent change in UACR in the first morning void urine at week 52 from baseline. The trial is registered at the clinical trials registry of University Hospital Medical Information Network (UMIN), trial identification number UMIN000001803. FINDINGS Between April 1, 2009, and March 31, 2012, we randomly allocated 170 patients to the eplerenone group and 166 patients to the placebo group. In the primary efficacy analysis, mean percent change in UACR from baseline was −17·3% (95% CI −33·65 to −0·94) for 158 patients in the eplerenone group compared with 10·3% (−6·75 to 22·3) for 146 patients in the placebo group (absolute difference −27·6% [–51·15 to −3·96]; p=0·0222). In the safety analyses, 53 (31%) of 169 patients in the eplerenone group had adverse events (five serious), as did 49 (30%) of 163 in the placebo group (seven serious). Although mean serum potassium concentration was higher in the eplerenone group than the placebo group, severe hyperkalaemia (>5·5 mmol/L) was not recorded in either group. INTERPRETATION Addition of low-dose eplerenone to renin-angiotensin system inhibitors might have renoprotective effects through reduction of albuminuria in hypertensive patients with non-diabetic chronic kidney disease, without serious safety concerns. FUNDING Pfizer.
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Endothelin receptor blockade ameliorates renal injury by inhibition of RhoA/Rho-kinase signalling in deoxycorticosterone acetate-salt hypertensive rats. J Hypertens 2014; 32:795-805. [PMID: 24463935 DOI: 10.1097/hjh.0000000000000092] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
PURPOSE OF REVIEW Excessive production of fibrosis is a feature of hypertension-induced renal injury. Activation of RhoA/Rho-kinase (ROCK) axis has been shown in deoxycorticosterone acetate (DOCA)-salt hypertensive rats. We assessed whether selective endothelin receptor blockers can attenuate renal fibrosis by inhibiting RhoA/ROCK axis in DOCA-salt rats. METHODS At 4 weeks after the start of DOCA-salt treatment and uninephrectomization, male Wistar rats were randomized into three groups for 4 weeks: vehicle, ABT-627 (endothelin-A receptor inhibitor) and A192621 (endothelin-B receptor inhibitor). RESULTS DOCA-salt was characterized by increased blood pressure, decreased renal function, increased proteinuria, increased glomerulosclerosis and tubulointerstitial fibrosis with myofibroblast accumulation, increased renal endothelin-1 levels and RhoA activity along with increased expression of connective tissue growth factor at both mRNA and protein levels as compared with uninephrectomized control male Wistar rats. Treatment with a selective mineralocorticoid receptor antagonist, eplerenone, ameliorated proteinuria. Impaired renal function and histological changes were overcome by treatment with ABT-627, but not with A192621. The beneficial effects of bosentan, a nonspecific endothelin receptor blocker, on proteinuria, RhoA activity, and connective tissue growth factor levels were similar to ABT-627. Furthermore, in an isolated perfuse kidney, a RhoA inhibitor, C3 exoenzyme, and two ROCK inhibitors, fasudil and Y-27632, significantly attenuated connective tissue growth factor levels. CONCLUSIONS These results indicate that DOCA-salt elevates renal endothelin-1 levels and RhoA activity via activation of mineralocorticoid receptor, resulting in renal fibrosis and proteinuria. Endothelin-A receptor blockade can attenuate DOCA-salt-induced renal fibrosis probably through the inhibition of RhoA/ROCK activity and connective tissue growth factor expression.
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Raff H, Gehrand A, Bruder ED, Hoffman MJ, Engeland WC, Moreno C. Renin knockout rat: control of adrenal aldosterone and corticosterone synthesis in vitro and adrenal gene expression. Am J Physiol Regul Integr Comp Physiol 2014; 308:R73-7. [PMID: 25394830 DOI: 10.1152/ajpregu.00440.2014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The classic renin-angiotensin system is partly responsible for controlling aldosterone secretion from the adrenal cortex via the peptide angiotensin II (ANG II). In addition, there is a local adrenocortical renin-angiotensin system that may be involved in the control of aldosterone synthesis in the zona glomerulosa (ZG). To characterize the long-term control of adrenal steroidogenesis, we utilized adrenal glands from renin knockout (KO) rats and compared steroidogenesis in vitro and steroidogenic enzyme expression to wild-type (WT) controls (Dahl S rat). Adrenal capsules (ZG; aldosterone production) and subcapsules [zona reticularis/fasciculata (ZFR); corticosterone production] were separately dispersed and studied in vitro. Plasma renin activity and ANG II concentrations were extremely low in the KO rats. Basal and cAMP-stimulated aldosterone production was significantly reduced in renin KO ZG cells, whereas corticosterone production was not different between WT and KO ZFR cells. As expected, adrenal renin mRNA expression was lower in the renin KO compared with the WT rat. Real-time PCR and immunohistochemical analysis showed a significant decrease in P450aldo (Cyp11b2) mRNA and protein expression in the ZG from the renin KO rat. The reduction in aldosterone synthesis in the ZG of the renin KO adrenal seems to be accounted for by a specific decrease in P450aldo and may be due to the absence of chronic stimulation of the ZG by circulating ANG II or to a reduction in locally released ANG II within the adrenal gland.
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Affiliation(s)
- Hershel Raff
- Endocrine Research Laboratory, Aurora St. Luke's Medical Center, Aurora Research Institute, Milwaukee, Wisconsin; Departments of Medicine, Surgery, and Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin;
| | - Ashley Gehrand
- Endocrine Research Laboratory, Aurora St. Luke's Medical Center, Aurora Research Institute, Milwaukee, Wisconsin
| | - Eric D Bruder
- Endocrine Research Laboratory, Aurora St. Luke's Medical Center, Aurora Research Institute, Milwaukee, Wisconsin
| | - Matthew J Hoffman
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin; and
| | - William C Engeland
- Department of Neuroscience, University of Minnesota, Minneapolis, Minnesota
| | - Carol Moreno
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin; and
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Johnson RJ, Lanaspa MA, Gabriela Sánchez-Lozada L, Rodriguez-Iturbe B. The discovery of hypertension: evolving views on the role of the kidneys, and current hot topics. Am J Physiol Renal Physiol 2014; 308:F167-78. [PMID: 25377913 DOI: 10.1152/ajprenal.00503.2014] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Primary hypertension is increasingly common and is associated with significant morbidity. Here, we review the history of its discovery and rise during the last century with an emphasis on studies trying to identify its cause. Early studies identified a defect in sodium excretion by the kidney as being central to the pathogenesis. Recent studies have focused on a variety of genetic, congenital (fetal programming), and acquired mechanisms for causing the defect in natriuresis. Certain risk factors are apparent, including genetic polymorphisms that regulate sodium excretion, a congenital reduction in nephron number, obesity and hyperleptinemia, an elevated sympathetic nervous system, diet (salt and fructose), and metabolic (hyperuricemia) mechanisms. The kidney shows evidence for renal arteriolar vasoconstriction, an intrarenal inflammatory response, local oxidative stress, and intrarenal activation of the renin-angiotensin system. Recent studies suggest that intrarenal T cells have an important role in causing hypertension to be persistent, likely due to the induction of a local autoimmune response to neoantigens such as heat shock protein 70 and protein aggregates formed by isoketals resulting from lipid peroxidation. Salt retention due to impairment in pressure-diuresis leads to the release of cardiotonic steroids and central nervous system effects that cause systemic vasoconstriction and a rise in blood pressure. Some recent studies suggest that salt may increase blood pressure not simply by effects on extracellular volume but rather as a consequence of hyperosmolarity. These new insights could lead to new approaches for the prevention and treatment of this important disease.
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Affiliation(s)
- Richard J Johnson
- Division of Renal Diseases and Hypertension, University of Colorado, Denver, Colorado;
| | - Miguel A Lanaspa
- Division of Renal Diseases and Hypertension, University of Colorado, Denver, Colorado
| | - L Gabriela Sánchez-Lozada
- Laboratory of Renal Physiopathology, Instituto Nacional de Cardiología Ignacio Chávez, Mexico City, Mexico; and
| | - Bernardo Rodriguez-Iturbe
- Hospital Universitario y Universidad del Zulia; and Instituto Venezolano de Investigaciones Científicas (IVIC)-Zulia, Maracaibo, Venezuela
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Spencer AG, Labonte ED, Rosenbaum DP, Plato CF, Carreras CW, Leadbetter MR, Kozuka K, Kohler J, Koo-McCoy S, He L, Bell N, Tabora J, Joly KM, Navre M, Jacobs JW, Charmot D. Intestinal inhibition of the Na+/H+ exchanger 3 prevents cardiorenal damage in rats and inhibits Na+ uptake in humans. Sci Transl Med 2014; 6:227ra36. [PMID: 24622516 DOI: 10.1126/scitranslmed.3007790] [Citation(s) in RCA: 111] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The management of sodium intake is clinically important in many disease states including heart failure, kidney disease, and hypertension. Tenapanor is an inhibitor of the sodium-proton (Na(+)/H(+)) exchanger NHE3, which plays a prominent role in sodium handling in the gastrointestinal tract and kidney. When administered orally to rats, tenapanor acted exclusively in the gastrointestinal tract to inhibit sodium uptake. We showed that the systemic availability of tenapanor was negligible through plasma pharmacokinetic studies, as well as autoradiography and mass balance studies performed with (14)C-tenapanor. In humans, tenapanor reduced urinary sodium excretion by 20 to 50 mmol/day and led to an increase of similar magnitude in stool sodium. In salt-fed nephrectomized rats exhibiting hypervolemia, cardiac hypertrophy, and arterial stiffening, tenapanor reduced extracellular fluid volume, left ventricular hypertrophy, albuminuria, and blood pressure in a dose-dependent fashion. We observed these effects whether tenapanor was administered prophylactically or after disease was established. In addition, the combination of tenapanor and the blood pressure medication enalapril improved cardiac diastolic dysfunction and arterial pulse wave velocity relative to enalapril monotherapy in this animal model. Tenapanor prevented increases in glomerular area and urinary KIM-1, a marker of renal injury. The results suggest that therapeutic alteration of sodium transport in the gastrointestinal tract instead of the kidney--the target of current drugs--could lead to improved sodium management in renal disease.
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Buglioni A, Cannone V, Cataliotti A, Sangaralingham SJ, Heublein DM, Scott CG, Bailey KR, Rodeheffer RJ, Dessì-Fulgheri P, Sarzani R, Burnett JC. Circulating aldosterone and natriuretic peptides in the general community: relationship to cardiorenal and metabolic disease. Hypertension 2014; 65:45-53. [PMID: 25368032 DOI: 10.1161/hypertensionaha.114.03936] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We sought to investigate the role of aldosterone as a mediator of disease and its relationship with the counter-regulatory natriuretic peptide (NP) system. We measured plasma aldosterone (n=1674; aged≥45 years old) in a random sample of the general population from Olmsted County, MN. In a multivariate logistic regression model, aldosterone analyzed as a continuous variable was associated with hypertension (odds ratio [OR]=1.75; 95% confidence interval [CI]=1.57-1.96; P<0.0001), obesity (OR=1.34; 95% CI=1.21-1.48; P<0.0001), chronic kidney disease (OR=1.39; 95% CI=1.22-1.60; P<0.0001), central obesity (OR=1.47; 95% CI=1.32-1.63; P<0.0001), metabolic syndrome (OR=1.41; 95% CI=1.26-1.58; P<0.0001), high triglycerides (OR=1.23; 95% CI=1.11-1.36; P<0.0001), concentric left ventricular hypertrophy (OR=1.22; 95% CI=1.09-1.38; P=0.0007), and atrial fibrillation (OR=1.24; 95% CI=1.01-1.53; P=0.04), after adjusting for age and sex. The associations with hypertension, central obesity, metabolic syndrome, triglycerides, and concentric left ventricular hypertrophy remained significant after further adjustment for body mass index, NPs, and renal function. Furthermore, aldosterone in the highest tertile correlated with lower NP levels and increased mortality. Importantly, most of these associations remained significant even after excluding subjects with aldosterone levels above the normal range. In conclusion, we report that aldosterone is associated with hypertension, chronic kidney disease, obesity, metabolic syndrome, concentric left ventricular hypertrophy, and lower NPs in the general community. Our data suggest that aldosterone, even within the normal range, may be a biomarker of cardiorenal and metabolic disease. Further studies are warranted to evaluate a therapeutic and preventive strategy to delay the onset and progression of disease, using mineralocorticoid antagonists or chronic NP administration in high-risk subjects identified by plasma aldosterone.
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Affiliation(s)
- Alessia Buglioni
- From the Cardiorenal Research Laboratory, Division of Cardiovascular Diseases, Departments of Medicine and Health Sciences Research, College of Medicine Mayo Clinic, Rochester, MN (A.B., V.C., A.C., S.J.S., D.M.H., C.G.S., K.R.B., R.J.R., J.C.B.); and Internal Medicine and Geriatrics, Department of Clinical and Molecular Science, University "Politecnica delle Marche" and Italian National Research Centre on Aging, IRCCS/INRCA, Ancona, Italy (A.B., P.D.-F., R.S.).
| | - Valentina Cannone
- From the Cardiorenal Research Laboratory, Division of Cardiovascular Diseases, Departments of Medicine and Health Sciences Research, College of Medicine Mayo Clinic, Rochester, MN (A.B., V.C., A.C., S.J.S., D.M.H., C.G.S., K.R.B., R.J.R., J.C.B.); and Internal Medicine and Geriatrics, Department of Clinical and Molecular Science, University "Politecnica delle Marche" and Italian National Research Centre on Aging, IRCCS/INRCA, Ancona, Italy (A.B., P.D.-F., R.S.)
| | - Alessandro Cataliotti
- From the Cardiorenal Research Laboratory, Division of Cardiovascular Diseases, Departments of Medicine and Health Sciences Research, College of Medicine Mayo Clinic, Rochester, MN (A.B., V.C., A.C., S.J.S., D.M.H., C.G.S., K.R.B., R.J.R., J.C.B.); and Internal Medicine and Geriatrics, Department of Clinical and Molecular Science, University "Politecnica delle Marche" and Italian National Research Centre on Aging, IRCCS/INRCA, Ancona, Italy (A.B., P.D.-F., R.S.)
| | - S Jeson Sangaralingham
- From the Cardiorenal Research Laboratory, Division of Cardiovascular Diseases, Departments of Medicine and Health Sciences Research, College of Medicine Mayo Clinic, Rochester, MN (A.B., V.C., A.C., S.J.S., D.M.H., C.G.S., K.R.B., R.J.R., J.C.B.); and Internal Medicine and Geriatrics, Department of Clinical and Molecular Science, University "Politecnica delle Marche" and Italian National Research Centre on Aging, IRCCS/INRCA, Ancona, Italy (A.B., P.D.-F., R.S.)
| | - Denise M Heublein
- From the Cardiorenal Research Laboratory, Division of Cardiovascular Diseases, Departments of Medicine and Health Sciences Research, College of Medicine Mayo Clinic, Rochester, MN (A.B., V.C., A.C., S.J.S., D.M.H., C.G.S., K.R.B., R.J.R., J.C.B.); and Internal Medicine and Geriatrics, Department of Clinical and Molecular Science, University "Politecnica delle Marche" and Italian National Research Centre on Aging, IRCCS/INRCA, Ancona, Italy (A.B., P.D.-F., R.S.)
| | - Christopher G Scott
- From the Cardiorenal Research Laboratory, Division of Cardiovascular Diseases, Departments of Medicine and Health Sciences Research, College of Medicine Mayo Clinic, Rochester, MN (A.B., V.C., A.C., S.J.S., D.M.H., C.G.S., K.R.B., R.J.R., J.C.B.); and Internal Medicine and Geriatrics, Department of Clinical and Molecular Science, University "Politecnica delle Marche" and Italian National Research Centre on Aging, IRCCS/INRCA, Ancona, Italy (A.B., P.D.-F., R.S.)
| | - Kent R Bailey
- From the Cardiorenal Research Laboratory, Division of Cardiovascular Diseases, Departments of Medicine and Health Sciences Research, College of Medicine Mayo Clinic, Rochester, MN (A.B., V.C., A.C., S.J.S., D.M.H., C.G.S., K.R.B., R.J.R., J.C.B.); and Internal Medicine and Geriatrics, Department of Clinical and Molecular Science, University "Politecnica delle Marche" and Italian National Research Centre on Aging, IRCCS/INRCA, Ancona, Italy (A.B., P.D.-F., R.S.)
| | - Richard J Rodeheffer
- From the Cardiorenal Research Laboratory, Division of Cardiovascular Diseases, Departments of Medicine and Health Sciences Research, College of Medicine Mayo Clinic, Rochester, MN (A.B., V.C., A.C., S.J.S., D.M.H., C.G.S., K.R.B., R.J.R., J.C.B.); and Internal Medicine and Geriatrics, Department of Clinical and Molecular Science, University "Politecnica delle Marche" and Italian National Research Centre on Aging, IRCCS/INRCA, Ancona, Italy (A.B., P.D.-F., R.S.)
| | - Paolo Dessì-Fulgheri
- From the Cardiorenal Research Laboratory, Division of Cardiovascular Diseases, Departments of Medicine and Health Sciences Research, College of Medicine Mayo Clinic, Rochester, MN (A.B., V.C., A.C., S.J.S., D.M.H., C.G.S., K.R.B., R.J.R., J.C.B.); and Internal Medicine and Geriatrics, Department of Clinical and Molecular Science, University "Politecnica delle Marche" and Italian National Research Centre on Aging, IRCCS/INRCA, Ancona, Italy (A.B., P.D.-F., R.S.)
| | - Riccardo Sarzani
- From the Cardiorenal Research Laboratory, Division of Cardiovascular Diseases, Departments of Medicine and Health Sciences Research, College of Medicine Mayo Clinic, Rochester, MN (A.B., V.C., A.C., S.J.S., D.M.H., C.G.S., K.R.B., R.J.R., J.C.B.); and Internal Medicine and Geriatrics, Department of Clinical and Molecular Science, University "Politecnica delle Marche" and Italian National Research Centre on Aging, IRCCS/INRCA, Ancona, Italy (A.B., P.D.-F., R.S.)
| | - John C Burnett
- From the Cardiorenal Research Laboratory, Division of Cardiovascular Diseases, Departments of Medicine and Health Sciences Research, College of Medicine Mayo Clinic, Rochester, MN (A.B., V.C., A.C., S.J.S., D.M.H., C.G.S., K.R.B., R.J.R., J.C.B.); and Internal Medicine and Geriatrics, Department of Clinical and Molecular Science, University "Politecnica delle Marche" and Italian National Research Centre on Aging, IRCCS/INRCA, Ancona, Italy (A.B., P.D.-F., R.S.)
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Loirand G, Pacaud P. Involvement of Rho GTPases and their regulators in the pathogenesis of hypertension. Small GTPases 2014; 5:1-10. [PMID: 25496262 DOI: 10.4161/sgtp.28846] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Proper regulation of arterial blood pressure is essential to allow permanent adjustment of nutrient and oxygen supply to organs and tissues according to their need. This is achieved through highly coordinated regulation processes controlling vascular resistance through modulation of arterial smooth muscle contraction, cardiac output, and kidney function. Members of the Rho family of small GTPases, in particular RhoA and Rac1, have been identified as key signaling molecules playing important roles in several different steps of these regulatory processes. Here, we review the current state of knowledge regarding the involvement of Rho GTPase signaling in the control of blood pressure and the pathogenesis of hypertension. We describe how knockout models in mouse, genetic, and pharmacological studies in human have been useful to address this question.
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Key Words
- AT1 receptor, type 1 Ang II receptor
- Ang II, angiotensine II
- ENaCs, epithelial Na+ channels
- Et-1, endothelin-1
- GAPs, GTPase-activating proteins
- GEFs, exchange factors
- GTPase activating proteins
- GTPases
- MLC, 20 kDa-myosin light chain
- MLCK, MLC kinase
- MLCP, MLC phosphatase
- NA, noradrenaline
- NHE3, sodium-hydrogen exchanger isoform 3.
- NO, nitric oxide
- NTS, nucleus tractus solitaries
- PDE5, type 5 phosphodiesterase
- PKG, cGMP-dependent protein kinase
- Rock, Rho-kinase
- SHR, spontaneously hypertensive rats
- SHRSP, stroke-prone SHR
- TxA2, thromboxane A2
- artery
- blood pressure
- cardiovascular
- eNOS, endothelial NO synthase
- exchange factors
- signal transduction
- small G proteins
- smooth muscle
- vasoconstriction
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Insulin resistance in chronic kidney disease is ameliorated by spironolactone in rats and humans. Kidney Int 2014; 87:749-60. [PMID: 25337775 DOI: 10.1038/ki.2014.348] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2014] [Revised: 08/24/2014] [Accepted: 08/28/2014] [Indexed: 12/27/2022]
Abstract
In this study, we examined the association between chronic kidney disease (CKD) and insulin resistance. In a patient cohort with nondiabetic stages 2-5 CKD, estimated glomerular filtration rate (eGFR) was negatively correlated and the plasma aldosterone concentration was independently associated with the homeostasis model assessment of insulin resistance. Treatment with the mineralocorticoid receptor blocker spironolactone ameliorated insulin resistance in patients, and impaired glucose tolerance was partially reversed in fifth/sixth nephrectomized rats. In these rats, insulin-induced signal transduction was attenuated, especially in the adipose tissue. In the adipose tissue of nephrectomized rats, nuclear mineralocorticoid receptor expression, expression of the mineralocorticoid receptor target molecule SGK-1, tissue aldosterone content, and expression of the aldosterone-producing enzyme CYP11B2 increased. Mineralocorticoid receptor activation in the adipose tissue was reversed by spironolactone. In the adipose tissue of nephrectomized rats, asymmetric dimethylarginine (ADMA; an uremic substance linking uremia and insulin resistance) increased, the expression of the ADMA-degrading enzymes DDAH1 and DDAH2 decreased, and the oxidative stress increased. All of these changes were reversed by spironolactone. In mature adipocytes, aldosterone downregulated both DDAH1 and DDAH2 expression, and ADMA inhibited the insulin-induced cellular signaling. Thus, activation of mineralocorticoid receptor and resultant ADMA accumulation in adipose tissue has, in part, a relevant role in the development of insulin resistance in CKD.
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131
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Pavlov TS, Levchenko V, Staruschenko A. Role of Rho GDP dissociation inhibitor α in control of epithelial sodium channel (ENaC)-mediated sodium reabsorption. J Biol Chem 2014; 289:28651-9. [PMID: 25164814 DOI: 10.1074/jbc.m114.558262] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The epithelial sodium channel (ENaC) is expressed in the aldosterone-sensitive distal nephron where it performs sodium reabsorption from the lumen. We have recently shown that ENaC activity contributes to the development of salt-induced hypertension as a result of deficiency of EGF level. Previous studies revealed that Rho GDP-dissociation inhibitor α (RhoGDIα) is involved in the control of salt-sensitive hypertension and renal injury via Rac1, which is one of the small GTPases activating ENaC. Here we investigated the intracellular mechanism mediating the involvement of the RhoGDIα/Rac1 axis in the control of ENaC and the effect of EGF on ENaC in this pathway. We demonstrated that RhoGDIα is highly expressed in the cortical collecting ducts of mice and rats, and its expression is down-regulated in Dahl salt-sensitive rats fed a high salt diet. Knockdown of RhoGDIα in cultured cortical collecting duct principal cells increased ENaC subunits expression and ENaC-mediated sodium reabsorption. Furthermore, RhoGDIα deficiency causes enhanced response to EGF treatment. Patch clamp analysis reveals that RhoGDIα significantly decreases ENaC current density and prevents its up-regulation by RhoA and Rac1. Inhibition of Rho kinase with Y27632 had no effects on ENaC response to EGF either in control or RhoGDIα knocked down cells. However, EGF treatment increased levels of active Rac1, which was further enhanced in RhoGDIα-deficient cells. We conclude that changes in the RhoGDIα-dependent pathway have a permissive role in the Rac1-mediated enhancement of ENaC activity observed in salt-induced hypertension.
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Affiliation(s)
- Tengis S Pavlov
- From the Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226
| | - Vladislav Levchenko
- From the Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226
| | - Alexander Staruschenko
- From the Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226
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132
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Kawarazaki W, Fujita T. Aberrant Rac1-mineralocorticoid receptor pathways in salt-sensitive hypertension. Clin Exp Pharmacol Physiol 2014; 40:929-36. [PMID: 24111570 DOI: 10.1111/1440-1681.12177] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2013] [Revised: 09/11/2013] [Accepted: 09/17/2013] [Indexed: 12/17/2022]
Abstract
According to Guyton's model, impaired renal sodium excretion plays a key role in the increased salt sensitivity of blood pressure (BP). Several factors contribute to impaired renal sodium excretion, including the sympathetic nervous system, the renin-angiotensin system and aldosterone. Accumulating evidence suggests that abnormalities in aldosterone and its receptor (i.e. the mineralocorticoid receptor (MR)) are involved in the development of salt-sensitive (SS) hypertension. Patients with metabolic syndrome often exhibit hyperaldosteronism and are susceptible to SS hypertension. Aldosterone secretion from the adrenal glands is not suppressed in obese hypertensive rats fed a high-salt diet because of the abundant production of adipocyte-derived aldosterone-releasing factors, which are independent of the negative feedback regulation of aldosterone secretion by the renin-angiotensin-aldosterone system. Increased plasma aldosterone levels lead to SS hypertension via MR activation in the kidney. Renal MR activity is increased in Dahl salt-sensitive rats fed a high-salt diet, despite the appropriate suppression of plasma aldosterone levels. In this rat strain, activation of MR in the distal nephron causes salt-induced hypertension. This paradoxical response of the MR to salt loading can be attributed to activation of Rac1, a small GTPase. In the presence of aldosterone, activated Rac1 synergistically and directly activates MR in a ligand-independent manner. Thus, Rac1 activation in the kidney determines the salt sensitivity of BP. Together, the available evidence suggests that the aberrant Rac1-MR pathway plays a key role in the development of SS hypertension.
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Affiliation(s)
- Wakako Kawarazaki
- Division of Clinical Epigenetics, Research Center for Advanced Science and Technology=1, The University of Tokyo=1, Tokyo, Japan
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Lal MA, Andersson AC, Katayama K, Xiao Z, Nukui M, Hultenby K, Wernerson A, Tryggvason K. Rhophilin-1 is a key regulator of the podocyte cytoskeleton and is essential for glomerular filtration. J Am Soc Nephrol 2014; 26:647-62. [PMID: 25071083 DOI: 10.1681/asn.2013111195] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Rhophilin-1 is a Rho GTPase-interacting protein, the biologic function of which is largely unknown. Here, we identify and describe the functional role of Rhophilin-1 as a novel podocyte-specific protein of the kidney glomerulus. Rhophilin-1 knockout mice were phenotypically normal at birth but developed albuminuria at about 2 weeks of age. Kidneys from severely albuminuric mice revealed widespread podocyte foot process effacement, thickening of the glomerular basement membrane, and FSGS-like lesions. The absence of any overt changes in the expression of podocyte proteins at the onset of proteinuria suggested that the primary cause of podocyte abnormalities in Rhpn1-null mice was the result of cell-autonomous, Rhophilin-1-dependent signaling events. In culture, Rhophilin-1 was detected at the plasma membrane leading edge of primary podocytes, where it elicited remodeling of the actin cytoskeleton network. This effect of Rhophilin-1 on actin cytoskeleton organization associated with inhibitory effects on Rho-dependent phosphorylation of the myosin regulatory light chain and stress fiber formation. Conversely, phosphorylation of myosin regulatory light chain increased in podocyte foot processes of Rhpn1(-/-) mice, implicating altered actinomyosin contractility in foot process effacement and compromised filtration capacity. Targeted deletion of RhoA in podocytes of Rhophilin-1 knockout mice exacerbated the renal injury. Taken together, our results indicate that Rhophilin-1 is essential for the integrity of the glomerular filtration barrier and that this protein is a key determinant of podocyte cytoskeleton architecture.
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Affiliation(s)
- Mark A Lal
- Division of Matrix Biology, Department of Medical Biochemistry and Biophysics
| | | | - Kan Katayama
- Division of Matrix Biology, Department of Medical Biochemistry and Biophysics
| | - Ziejie Xiao
- Division of Matrix Biology, Department of Medical Biochemistry and Biophysics
| | - Masatoshi Nukui
- Division of Matrix Biology, Department of Medical Biochemistry and Biophysics
| | - Kjell Hultenby
- Department of Laboratory Medicine, Division of Clinical Research Center, and
| | - Annika Wernerson
- Division of Renal Medicine, Department of Clinical Science, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden
| | - Karl Tryggvason
- Division of Matrix Biology, Department of Medical Biochemistry and Biophysics,
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135
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Abstract
The primary adrenal cortical steroid hormones, aldosterone, and the glucocorticoids cortisol and corticosterone, act through the structurally similar mineralocorticoid (MR) and glucocorticoid receptors (GRs). Aldosterone is crucial for fluid, electrolyte, and hemodynamic homeostasis and tissue repair; the significantly more abundant glucocorticoids are indispensable for energy homeostasis, appropriate responses to stress, and limiting inflammation. Steroid receptors initiate gene transcription for proteins that effect their actions as well as rapid non-genomic effects through classical cell signaling pathways. GR and MR are expressed in many tissues types, often in the same cells, where they interact at molecular and functional levels, at times in synergy, others in opposition. Thus the appropriate balance of MR and GR activation is crucial for homeostasis. MR has the same binding affinity for aldosterone, cortisol, and corticosterone. Glucocorticoids activate MR in most tissues at basal levels and GR at stress levels. Inactivation of cortisol and corticosterone by 11β-HSD2 allows aldosterone to activate MR within aldosterone target cells and limits activation of the GR. Under most conditions, 11β-HSD1 acts as a reductase and activates cortisol/corticosterone, amplifying circulating levels. 11β-HSD1 and MR antagonists mitigate inappropriate activation of MR under conditions of oxidative stress that contributes to the pathophysiology of the cardiometabolic syndrome; however, MR antagonists decrease normal MR/GR functional interactions, a particular concern for neurons mediating cognition, memory, and affect.
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Affiliation(s)
- Elise Gomez-Sanchez
- G.V.(Sonny) Montgomery V.A. Medical Center and Department of Medicine, University of Mississippi Medical Center, Jackson, Mississippi
| | - Celso E. Gomez-Sanchez
- G.V.(Sonny) Montgomery V.A. Medical Center and Department of Medicine, University of Mississippi Medical Center, Jackson, Mississippi
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136
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Kawada N, Isaka Y, Kitamura H, Rakugi H, Moriyama T. A pilot study of the effects of eplerenone add-on therapy in patients taking renin-angiotensin system blockers. J Renin Angiotensin Aldosterone Syst 2014; 16:360-5. [PMID: 24961502 DOI: 10.1177/1470320314532509] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
HYPOTHESIS This study determined the parameters for predicting the clinical effects of eplerenone (Ep) add-on therapy on blood pressure (BP) and proteinuria in patients taking angiotensin-converting enzyme inhibitors (ACEis) or angiotensin II type I receptor blockers (ARBs). MATERIALS AND METHODS Patients were treated with a gradual increase of Ep to a final dose of 50 mg/day for 2 months. In 35 patients, the efficacy of Ep was evaluated by peripheral BP, proteinuria, and the transtubular K gradient (TTKG). Fifteen patients had additional analysis for central BP, plasma renin activity (PRA) and plasma aldosterone concentration (PAC), measured in the supine position, and 24-hour urine collection before and after receiving Ep. RESULTS Ep add-on therapy reduced the mean arterial pressure (p=0.0005) and central BP (p=0.009) independently to the baseline PAC. Ep induced PRA, but failed to show effects on PAC, TTKG, or albuminuria. Correlation analysis showed inverse relationships between the percent reduction in albuminuria and baseline PAC. CONCLUSIONS Ep add-on therapy in patients taking renin-angiotensin system blockers is expected to reduce BP, even in patients with low PAC. In contrast, the anti-proteinuric action of Ep is dependent on baseline plasma aldosterone levels. TTKG is not appropriate for evaluating the efficacy of Ep.
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Affiliation(s)
| | - Yoshitaka Isaka
- Division of Geriatric Medicine and Nephrology, Osaka University Graduate School of Medicine, Japan
| | - Harumi Kitamura
- Division of Geriatric Medicine and Nephrology, Osaka University Graduate School of Medicine, Japan
| | - Hiromi Rakugi
- Division of Geriatric Medicine and Nephrology, Osaka University Graduate School of Medicine, Japan
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137
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Abstract
An essential link between the kidney and blood pressure control has long been known. Here, we review evidence supporting the premise that an impaired capacity of the kidney to excrete sodium in response to elevated blood pressure is a major contributor to hypertension, irrespective of the initiating cause. In this regard, recent work suggests that novel pathways controlling key sodium transporters in kidney epithelia have a critical impact on hypertension pathogenesis, supporting a model in which impaired renal sodium excretion is a final common pathway through which vascular, neural, and inflammatory responses raise blood pressure. We also address recent findings calling into question long-standing notions regarding the relationship between sodium intake and changes in body fluid volume. Expanded understanding of the role of the kidney as both a cause and target of hypertension highlights key aspects of pathophysiology and may lead to identification of new strategies for prevention and treatment.
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138
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Abstract
Although blockade of the renin-angiotensin-aldosterone system with angiotensin-converting enzyme inhibitors or angiotensin-receptor blockers has become standard therapy for chronic kidney disease (CKD), renewed interest in the role of aldosterone in mediating the injuries and progressive insults of CKD has highlighted the potential role of treatments targeting the mineralocorticoid receptor (MR). Although salt restriction is an important component of mitigating the profibrotic effects of MR activation, a growing body of literature has shown that MR antagonists, spironolactone and eplerenone, can reduce proteinuria and blood pressure in patients at all stages of CKD. These agents carry a risk of hyperkalemia, but this risk likely can be predicted based on baseline renal function and mitigated using dietary modifications and adjustments of concomitant medications. Data on hard outcomes, such as progression to end-stage renal disease and overall mortality, still are lacking in patients with CKD.
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Affiliation(s)
- Jamie S Hirsch
- Department of Medicine, Division of Nephrology, Columbia University College of Physicians and Surgeons, New York, NY
| | - Yelena Drexler
- Department of Medicine, Division of Nephrology, Columbia University College of Physicians and Surgeons, New York, NY
| | - Andrew S Bomback
- Department of Medicine, Division of Nephrology, Columbia University College of Physicians and Surgeons, New York, NY.
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139
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Salt, the renin-angiotensin-aldosterone system and resistant hypertension. Hypertens Res 2014; 36:657-60. [PMID: 23912973 DOI: 10.1038/hr.2013.69] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Revised: 03/08/2013] [Accepted: 04/10/2013] [Indexed: 01/22/2023]
Abstract
High salt intake is a risk for developing resistant hypertension, and even under triple therapy with diuretics, an angiotensin-converting enzyme inhibitor/angiotensin receptor blocker and a calcium channel blocker, the volume is occasionally not controlled. In such cases, a mineralocorticoid receptor (MR) antagonist additively lowers the circulating blood volume and blood pressure despite the lower circulating aldosterone level. This mechanism may be explained by the increase in the number of MR under some conditions or the activation of these receptors independent of aldosterone. Future diagnostic tools to evaluate receptor activity may be valuable for the proper diagnosis and choice of therapy. Additionally, basic research has suggested that oxidative stress and the renin-angiotensin-aldosterone system in the brain represent new targets for the treatment of resistant hypertension.
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140
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Adam O, Laufs U. Rac1-mediated effects of HMG-CoA reductase inhibitors (statins) in cardiovascular disease. Antioxid Redox Signal 2014; 20:1238-50. [PMID: 23919665 DOI: 10.1089/ars.2013.5526] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
SIGNIFICANCE HMG-CoA reductase inhibitors (statins) lower serum cholesterol concentrations and are beneficial in the primary and secondary prevention of coronary heart disease. The positive clinical effects have only partially been reproduced with other lipid-lowering interventions suggesting potential statin effects in addition to cholesterol lowering. In experimental models, direct beneficial cardiovascular effects that are mediated by the inhibition of isoprenoids have been documented, which serve as lipid attachments for intracellular signaling molecules such as small Rho guanosine triphosphate-binding proteins, whose membrane localization and function are dependent on isoprenylation. RECENT ADVANCES Rac1 GTPase is an established master regulator of cell motility through the cortical actin reorganization and of reactive oxygen species generation through the regulation of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity. CRITICAL ISSUES Observations in cells, animals, and humans have implicated the activation of Rac1 GTPase as a key component of cardiovascular pathologies, including the endothelial dysfunction, cardiac hypertrophy and fibrosis, atrial fibrillation, stroke, hypertension, and chronic kidney disease. However, the underlying signal transduction remains incompletely understood. FUTURE DIRECTIONS Based on the recent advance made in Rac1 research in the cardiovascular system by using mouse models with transgenic overexpression of activated Rac1 or conditional knockout, as well as Rac1-specific small molecule inhibitor NSC 23766, the improved understanding of the Rac1-mediated effects statins may help to identify novel therapeutic targets and strategies.
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Affiliation(s)
- Oliver Adam
- Klinik für Innere Medizin III, Kardiologie, Angiologie und Internistische Intensivmedizin, Universitätsklinikum des Saarlandes , Homburg, Germany
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141
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Abstract
The mineralocorticoid receptor (MR) is a ligand-dependent transcription factor that physiologically regulates water-electrolyte homeostasis and controls blood pressure. The MR can also elicit inflammatory and remodeling processes in the cardiovascular system and the kidneys, which require the presence of additional pathological factors like for example nitrosative stress. However, the underlying molecular mechanism(s) for pathophysiological MR effects remain(s) elusive. The inactive MR is located in the cytosol associated with chaperone molecules including HSP90. After ligand binding, the MR monomer rapidly translocates into the nucleus while still being associated to HSP90 and after dissociation from HSP90 binds to hormone-response-elements called glucocorticoid response elements (GREs) as a dimer. There are indications that rapid MR trafficking is modulated in the presence of high salt, oxidative or nitrosative stress, hypothetically by induction or posttranslational modifications. Additionally, glucocorticoids and the enzyme 11beta hydroxysteroid dehydrogenase may also influence MR activation. Because MR trafficking and its modulation by micro-milieu factors influence MR cellular localization, it is not only relevant for genomic but also for nongenomic MR effects.
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Affiliation(s)
- M Gekle
- Julius Bernstein Institute of Physiology, Martin Luther University Halle-Wittenberg, Germany
| | - M Bretschneider
- Julius Bernstein Institute of Physiology, Martin Luther University Halle-Wittenberg, Germany
| | - S Meinel
- Julius Bernstein Institute of Physiology, Martin Luther University Halle-Wittenberg, Germany
| | - S Ruhs
- Julius Bernstein Institute of Physiology, Martin Luther University Halle-Wittenberg, Germany
| | - C Grossmann
- Julius Bernstein Institute of Physiology, Martin Luther University Halle-Wittenberg, Germany.
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142
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Yoshida S, Ishizawa K, Ayuzawa N, Ueda K, Takeuchi M, Kawarazaki W, Fujita T, Nagase M. Local mineralocorticoid receptor activation and the role of Rac1 in obesity-related diabetic kidney disease. Nephron Clin Pract 2014; 126:16-24. [PMID: 24603367 DOI: 10.1159/000358758] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Accepted: 01/14/2014] [Indexed: 02/01/2023] Open
Abstract
BACKGROUND/AIMS Obesity and diabetes are intimately interrelated, and are independent risk factors for kidney disease. Overactivation of mineralocorticoid receptor (MR) is implicated in end organ damage of both pathologies. But the underlying mechanism of MR activation in kidney remains uncertain. We explored the involvement of Rac1, which we previously identified as a ligand-independent MR activator, in renal MR activation in vitro and in vivo. METHODS We evaluated the MR activity and Rac1 activity under high-glucose stimulation using luciferase reporter system and glutathione S-transferase pull-down assay in cultured mesangial cells. To elucidate the role of Rac1 in vivo, we employed KKA(y), a mouse model of obesity-related type 2 diabetes, which spontaneously developed massive albuminuria and distinct glomerular lesions accompanied by increased plasma aldosterone concentration. RESULTS High-glucose stimulation increased Rac1 activity and MR transcriptional activity in cultured mesangial cells. Overexpression of constitutively active Rac1 activated MR, and glucose-induced MR activation was suppressed by overexpression of dominant negative Rac1 or Rac inhibitor EHT1864. In KKA(y), renal Rac1 was activated, and nuclear MR was increased. EHT1864 treatment suppressed renal Rac1 and MR activity and mitigated renal pathology of KKA(y) without changing plasma aldosterone concentration. CONCLUSION Our results suggest that MR activation plays an important role in the nephropathy of KKA(y) mice, and that glucose-induced Rac1 activation, in addition to hyperaldosteronemia, contributes to their renal MR activation. Along with MR blockade, Rac inhibition may potentially be a preferred option in the treatment of nephropathy in obesity-related diabetic patients.
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Affiliation(s)
- Shigetaka Yoshida
- Department of Nephrology and Endocrinology, The University of Tokyo Graduate School of Medicine, Tokyo, Japan
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143
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Fujita T. Mechanism of salt-sensitive hypertension: focus on adrenal and sympathetic nervous systems. J Am Soc Nephrol 2014; 25:1148-55. [PMID: 24578129 DOI: 10.1681/asn.2013121258] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
A central role for the kidney among the systems contributing to BP regulation and the development of hypertension has been proposed. Both the aldosterone/mineralocorticoid receptor pathway and the renal sympathetic nervous system have important roles in the regulation of renal excretory function and BP control, but the mechanisms underlying these processes have remained unclear. However, recent studies revealed the activation of two pathways in salt-sensitive hypertension. Notably, Rac1, a member of the Rho-family of small GTP binding proteins, was identified as a novel ligand-independent modulator of mineralocorticoid receptor activity. Furthermore, these studies point to crucial roles for the Rac1-mineralocorticoid receptor-NCC/ENaC and the renal β-adrenergic stimulant-glucocorticoid receptor-WNK4-NCC pathways in certain rodent models of salt-sensitive hypertension. The nuclear mineralocorticoid and glucocorticoid receptors may contribute to impaired renal excretory function and the resulting salt-sensitive hypertension by increasing sodium reabsorption at different tubular segments. This review provides an in-depth discussion of the evidence supporting these conclusions and considers the significance with regard to treating salt-sensitive hypertension and salt-induced cardiorenal injury.
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Affiliation(s)
- Toshiro Fujita
- Department of Clinical Epigenetics, Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan; and CREST, Tokyo, Japan
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144
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Inoue R, Asanuma K, Seki T, Nagase M, Osafune K. [New therapeutic insights for chronic kidney disease provided by podocytology]. Nihon Yakurigaku Zasshi 2014; 143:27-33. [PMID: 24420134 DOI: 10.1254/fpj.143.27] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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145
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Abstract
SIGNIFICANCE Renal oxidative stress can be a cause, a consequence, or more often a potentiating factor for hypertension. Increased reactive oxygen species (ROS) in the kidney have been reported in multiple models of hypertension and related to renal vasoconstriction and alterations of renal function. Nicotinamide adenine dinucleotide phosphate oxidase is the central source of ROS in the hypertensive kidney, but a defective antioxidant system also can contribute. RECENT ADVANCES Superoxide has been identified as the principal ROS implicated for vascular and tubular dysfunction, but hydrogen peroxide (H2O2) has been implicated in diminishing preglomerular vascular reactivity, and promoting medullary blood flow and pressure natriuresis in hypertensive animals. CRITICAL ISSUES AND FUTURE DIRECTIONS Increased renal ROS have been implicated in renal vasoconstriction, renin release, activation of renal afferent nerves, augmented contraction, and myogenic responses of afferent arterioles, enhanced tubuloglomerular feedback, dysfunction of glomerular cells, and proteinuria. Inhibition of ROS with antioxidants, superoxide dismutase mimetics, or blockers of the renin-angiotensin-aldosterone system or genetic deletion of one of the components of the signaling cascade often attenuates or delays the onset of hypertension and preserves the renal structure and function. Novel approaches are required to dampen the renal oxidative stress pathways to reduced O2(-•) rather than H2O2 selectivity and/or to enhance the endogenous antioxidant pathways to susceptible subjects to prevent the development and renal-damaging effects of hypertension.
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Affiliation(s)
- Magali Araujo
- Hypertension, Kidney and Vascular Research Center, Georgetown University , Washington, District of Columbia
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146
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Mouawad F, Aoudjit L, Jiang R, Szaszi K, Takano T. Role of guanine nucleotide exchange factor-H1 in complement-mediated RhoA activation in glomerular epithelial cells. J Biol Chem 2013; 289:4206-18. [PMID: 24356971 DOI: 10.1074/jbc.m113.506816] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Visceral glomerular epithelial cells (GEC), also known as podocytes, are vital for the structural and functional integrity of the glomerulus. The actin cytoskeleton plays a central role in maintaining GEC morphology. In a rat model of experimental membranous nephropathy (passive Heymann nephritis (PHN)), complement C5b-9-induced proteinuria was associated with the activation of the actin regulator small GTPase, RhoA. The mechanisms of RhoA activation, however, remained unknown. In this study, we explored the role of the epithelial guanine nucleotide exchange factor, GEF-H1, in complement-induced RhoA activation. Using affinity precipitation to monitor GEF activity, we found that GEF-H1 was activated in glomeruli isolated from rats with PHN. Complement C5b-9 also induced parallel activation of GEF-H1 and RhoA in cultured GEC. In GEC in which GEF-H1 was knocked down, both basal and complement-induced RhoA activity was reduced. On the other hand, GEF-H1 knockdown augmented complement-mediated cytolysis, suggesting a role for GEF-H1 and RhoA in protecting GEC from cell death. The MEK1/2 inhibitor, U0126, and mutation of the ERK-dependent phosphorylation site (T678A) prevented complement-induced GEF-H1 activation, indicating a role for the ERK pathway. Further, complement induced GEF-H1 and microtubule accumulation in the perinuclear region. However, both the perinuclear accumulation and the activation of GEF-H1 were independent of microtubules and myosin-mediated contractility, as shown using drugs that interfere with microtubule dynamics and myosin II activity. In summary, we have identified complement-induced ERK-dependent GEF-H1 activation as the upstream mechanism of RhoA stimulation, and this pathway has a protective role against cell death.
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Affiliation(s)
- Flaviana Mouawad
- From the Department of Medicine, McGill University Health Centre, Montreal, Quebec H3A 2B4, Canada and
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147
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Tsukamoto Y, Mano T, Sakata Y, Ohtani T, Takeda Y, Tamaki S, Omori Y, Ikeya Y, Saito Y, Ishii R, Higashimori M, Kaneko M, Miwa T, Yamamoto K, Komuro I. A novel heart failure mice model of hypertensive heart disease by angiotensin II infusion, nephrectomy, and salt loading. Am J Physiol Heart Circ Physiol 2013; 305:H1658-67. [DOI: 10.1152/ajpheart.00349.2013] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Although the mouse heart failure (HF) model of hypertensive heart disease (HHD) is useful to investigate the pathophysiology and new therapeutic targets for HHD, the model using simple experimental procedures and stable phenotypes has not been established. This study aimed to develop a novel mouse HF model of HHD by combining salt loading and uninephrectomy with ANG II infusion. Eight-week-old C57BL/6 male mice were treated with ANG II infusion (AT), ANG II infusion and uninephrectomy (AN), ANG II infusion and salt loading (AS), or ANG II infusion, uninephrectomy, and salt loading (ANS). Systolic blood pressure was significantly elevated and left ventricular (LV) hypertrophy was found in AT, AN, AS, and ANS mice, and there were no significant differences in those parameters between the four groups. At 6 wk after the procedures, only ANS mice showed significant decreases in LV fractional shortening and increases in lung weight with a high incidence. This phenotype was reproducible, and there were few perioperative or early deaths in the experimental procedures. Severe LV fibrosis was found in ANS mice. Oxidative stress was enhanced and small GTPase Rac1 activity was upregulated in the hearts of ANS mice. After the addition of salt loading and uninephrectomy to the ANG II infusion mouse model, cardiac function was significantly impaired, and mice developed HF. This might be a novel and useful mouse HF model to study the transition from compensated LV hypertrophy to HF in HHD.
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Affiliation(s)
- Yasumasa Tsukamoto
- Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Suita, Japan
- Genome Information Research Center, Osaka University, Suita, Japan
| | - Toshiaki Mano
- Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Suita, Japan
- Genome Information Research Center, Osaka University, Suita, Japan
| | - Yasushi Sakata
- Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Suita, Japan
| | - Tomohito Ohtani
- Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Suita, Japan
| | - Yasuharu Takeda
- Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Suita, Japan
| | - Shunsuke Tamaki
- Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Suita, Japan
- Genome Information Research Center, Osaka University, Suita, Japan
| | - Yosuke Omori
- Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Suita, Japan
- Genome Information Research Center, Osaka University, Suita, Japan
| | - Yukitoshi Ikeya
- Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Suita, Japan
- Division of Cardiology, Department of Internal Medicine, Nihon University School of Medicine, Tokyo, Japan
| | - Yuki Saito
- Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Suita, Japan
- Division of Cardiology, Department of Internal Medicine, Nihon University School of Medicine, Tokyo, Japan
| | - Ryohei Ishii
- Department of Mechanical Engineering, Osaka University, Suita, Japan; and
| | | | - Makoto Kaneko
- Department of Mechanical Engineering, Osaka University, Suita, Japan; and
| | - Takeshi Miwa
- Genome Information Research Center, Osaka University, Suita, Japan
| | - Kazuhiro Yamamoto
- Department of Molecular Medicine and Therapeutics, Faculty of Medicine, Tottori University, Yonago, Japan
| | - Issei Komuro
- Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Suita, Japan
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148
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Babelova A, Jansen F, Sander K, Löhn M, Schäfer L, Fork C, Ruetten H, Plettenburg O, Stark H, Daniel C, Amann K, Pavenstädt H, Jung O, Brandes RP. Activation of Rac-1 and RhoA contributes to podocyte injury in chronic kidney disease. PLoS One 2013; 8:e80328. [PMID: 24244677 PMCID: PMC3820652 DOI: 10.1371/journal.pone.0080328] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Accepted: 10/02/2013] [Indexed: 12/12/2022] Open
Abstract
Rho-family GTPases like RhoA and Rac-1 are potent regulators of cellular signaling that control gene expression, migration and inflammation. Activation of Rho-GTPases has been linked to podocyte dysfunction, a feature of chronic kidney diseases (CKD). We investigated the effect of Rac-1 and Rho kinase (ROCK) inhibition on progressive renal failure in mice and studied the underlying mechanisms in podocytes. SV129 mice were subjected to 5/6-nephrectomy which resulted in arterial hypertension and albuminuria. Subgroups of animals were treated with the Rac-1 inhibitor EHT1846, the ROCK inhibitor SAR407899 and the ACE inhibitor Ramipril. Only Ramipril reduced hypertension. In contrast, all inhibitors markedly attenuated albumin excretion as well as glomerular and tubulo-interstitial damage. The combination of SAR407899 and Ramipril was more effective in preventing albuminuria than Ramipril alone. To study the involved mechanisms, podocytes were cultured from SV129 mice and exposed to static stretch in the Flexcell device. This activated RhoA and Rac-1 and led via TGFβ to apoptosis and a switch of the cells into a more mesenchymal phenotype, as evident from loss of WT-1 and nephrin and induction of α-SMA and fibronectin expression. Rac-1 and ROCK inhibition as well as blockade of TGFβ dramatically attenuated all these responses. This suggests that Rac-1 and RhoA are mediators of podocyte dysfunction in CKD. Inhibition of Rho-GTPases may be a novel approach for the treatment of CKD.
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Affiliation(s)
| | - Felix Jansen
- Physiology I, Goethe-University, Frankfurt am Main, Germany
| | - Kerstin Sander
- Institute for Pharmaceutical Chemistry, Goethe-University, Frankfurt am Main, Germany
| | | | - Liliana Schäfer
- General Pharmacology and Toxicology, Goethe-University, Frankfurt am Main, Germany
| | - Christian Fork
- Physiology I, Goethe-University, Frankfurt am Main, Germany
| | | | | | - Holger Stark
- Institute for Pharmaceutical Chemistry, Goethe-University, Frankfurt am Main, Germany
| | - Christoph Daniel
- Department of Pathology, Nephropathology, University of Erlangen-Nürnberg, Erlangen, Germany
| | - Kerstin Amann
- Department of Pathology, Nephropathology, University of Erlangen-Nürnberg, Erlangen, Germany
| | - Hermann Pavenstädt
- Department of Internal Medicine D, University Hospital Münster, Münster, Germany
| | - Oliver Jung
- Physiology I, Goethe-University, Frankfurt am Main, Germany
- Internal Medicine/Nephrology, Goethe-University, Frankfurt am Main, Germany
| | - Ralf P. Brandes
- Physiology I, Goethe-University, Frankfurt am Main, Germany
- * E-mail:
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149
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Ando K, Kawarazaki H, Miura K, Matsuura H, Watanabe Y, Yoshita K, Kawamura M, Kusaka M, Kai H, Tsuchihashi T, Kawano Y. [Scientific Statement]. Hypertens Res 2013; 36:1009-19. [DOI: 10.1038/hr.2013.102] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2013] [Accepted: 07/24/2013] [Indexed: 02/05/2023]
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150
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Myocardial Rac1 exhibits partial involvement in thyroxin-induced cardiomyocyte hypertrophy and its inhibition is not sufficient to improve cardiac dysfunction or contractile abnormalities in mouse papillary muscles. J Cardiovasc Pharmacol 2013; 61:536-44. [PMID: 23429587 DOI: 10.1097/fjc.0b013e31828d4b9d] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
: Development of cardiac hypertrophy after thyroxin (T4) treatment is well recognized. Recently, we observed that T4-induced cardiac hypertrophy is associated with increased cardiac Rac1 expression and activity. Whether this Rac1 increase has a role in inducing this cardiac phenotype is, however, still unknown. Here, we showed that T4 treatment (500 µg/kg/d) for 2 weeks resulted in increased myocardial Rac1 activity with subsequent hypertension, cardiac hypertrophy, and left ventricular systolic dysfunction in vivo. Isolated right ventricular papillary muscles of T4-treated mice maintained their peak isometric active developed tension but exhibited significant decreases in their corresponding time to peak and in relaxation times. Positive inotropic responses to increasing pacing rate and β-adrenergic stimulation were also depressed in these muscles. Pravastatin (10 mg/kg/d), a Rac1 inhibitor, significantly decreased myocardial Rac1 activity, hypertension, and cardiomyocyte size in T4-treated mice but could not attenuate gross heart weight or functional cardiac changes in these mice. Our data showed that T4 could activate different signaling pathways with distinct cardiovascular outcomes. We also provide the first mechanistic evidence for the partial involvement of Rac1 activation in T4-induced cardiomyocyte hypertrophy and reveal a putative role for Rac1 in the development of T4-induced hypertension.
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