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Kukida M, Amioka N, Ye D, Chen H, Moorleghen JJ, Liang CL, Howatt DA, Katsumata Y, Yanagita M, Sawada H, Daugherty A, Lu HS. Manipulation of components of the renin angiotensin system in renal proximal tubules fails to alter atherosclerosis in hypercholesterolemic mice. Front Cardiovasc Med 2023; 10:1250234. [PMID: 37655218 PMCID: PMC10466789 DOI: 10.3389/fcvm.2023.1250234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Accepted: 08/03/2023] [Indexed: 09/02/2023] Open
Abstract
Background and objective Whole body manipulation of the renin-angiotensin system (RAS) consistently exerts profound effects on experimental atherosclerosis development. A deficit in the literature has been a lack of attention to the effects of sex. Also, based on data with gene-deleted mice, the site of RAS activity that influences lesion formation is at an unknown distant location. Since angiotensin (AngII) concentrations are high in kidney and the major components of the RAS are present in renal proximal tubule cells (PTCs), this study evaluated the role of the RAS in PTCs in atherosclerosis development. Methods and results Mice with an LDL receptor -/- background were fed Western diet to induce hypercholesterolemia and atherosclerosis. We first demonstrated the role of AT1 receptor antagonism on atherosclerosis in both sexes. Losartan, an AngII type 1 (AT1) receptor blocker, had greater blood pressure-lowering effects in females than males, but equivalent effects between sexes in reducing atherosclerotic lesion size. To determine the roles of renal AT1a receptor and angiotensin-converting enzyme (ACE), either component was deleted in PTCs after weaning using a tamoxifen-inducible Cre expressed under the control of an Ndrg1 promoter. Despite profound deletion of AT1a receptor or ACE in PTCs, the absence of either protein did not influence development of atherosclerosis in either sex. Conversely, mice expressing human angiotensinogen and renin in PTCs or expressing human angiotensinogen in liver but human renin in PTCs did not change atherosclerotic lesion size in male mice. Conclusion Whole-body AT1R inhibition reduced atherosclerosis equivalently in both male and female mice; however, PTC-specific manipulation of the RAS components had no effects on hypercholesterolemia-induced atherosclerosis.
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Affiliation(s)
- Masayoshi Kukida
- Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY, United States
| | - Naofumi Amioka
- Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY, United States
| | - Dien Ye
- Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY, United States
| | - Hui Chen
- Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY, United States
| | - Jessica J. Moorleghen
- Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY, United States
| | - Ching-Ling Liang
- Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY, United States
| | - Deborah A. Howatt
- Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY, United States
| | - Yuriko Katsumata
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, United States
- Department of Biostatistics, University of Kentucky, Lexington, KY, United States
| | - Motoko Yanagita
- Department of Nephrology, Kyoto University Graduate School of Medicine, Kyoto, Japan
- Institute for the Advanced Study of Human Biology (WPI-ASHBi), Kyoto University, Kyoto, Japan
| | - Hisashi Sawada
- Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY, United States
- Saha Aortic Center, University of Kentucky, Lexington, KY, United States
- Department of Physiology, University of Kentucky, Lexington, KY, United States
| | - Alan Daugherty
- Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY, United States
- Saha Aortic Center, University of Kentucky, Lexington, KY, United States
- Department of Physiology, University of Kentucky, Lexington, KY, United States
| | - Hong S. Lu
- Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY, United States
- Saha Aortic Center, University of Kentucky, Lexington, KY, United States
- Department of Physiology, University of Kentucky, Lexington, KY, United States
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2
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Niu P, Ren X, Wu M, Wan S, Zheng Y, Jiao X, Yan L, Cao H, Yang L, Shao F. Effect of intrarenal renin-angiotensin-aldosterone system on renal function in patients after cardiac surgery. Medicine (Baltimore) 2022; 101:e28854. [PMID: 35363185 PMCID: PMC9282047 DOI: 10.1097/md.0000000000028854] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Accepted: 01/28/2022] [Indexed: 01/04/2023] Open
Abstract
The aim of the study was to investigate the influence of intrarenal RAS on the decrease of renal function in patients undergoing cardiac surgery with cardiopulmonary bypass. This observational study investigated the activation of intrarenal RAS in 24 patients with AKI after cardiac surgery with cardiopulmonary bypass. The activation of intrarenal RAS was determined by urinary angiotensinogen (uAGT), which was measured at 12 hours before surgery, 0 and12 hours after surgery. The results were compared with those of 21 patients without AKI after cardiac surgery with cardiopulmonary bypass. Clinical and laboratory data were collected. Compared with baseline, all patients with cardiac surgery had activation of intrarenal RAS at 0 and 12 hours after surgery. The activation of intrarenal RAS was found significantly higher at both 0 and 12 hours after surgery in AKI group versus non AKI group (6.18 ± 1.93 ng/mL vs 3.49 ± 1.71 ng/mL, 16.38 ± 7.50 ng/mL vs 6.04 ± 2.59 ng/mL, respectively). There was a positive correlation between the activation of RAS at 0 hour after surgery and the decrease of renal function at 48 hours after surgery (r = 0.654, P = .001). These findings suggest that uAGT might be a suitable biomarker for prediction of the occurrence and severity of AKI after cardiac surgery. Inhibition of intrarenal RAS activation might be one the path of future treatment for this type of disease.
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Affiliation(s)
- Peiyuan Niu
- Department of Nephrology, Henan Provincial People's Hospital; People's Hospital of Zhengzhou University, People's Hospital of Henan University, Zhengzhou, Henan, China
- Henan Key Laboratory of Kidney Disease and Immunology, Zhengzhou, Henan, China
- Henan Provincial Clinical Research Center for Kidney Disease, Zhengzhou, Henan, China
| | - Xuejing Ren
- Department of Nephrology, Henan Provincial People's Hospital; People's Hospital of Zhengzhou University, People's Hospital of Henan University, Zhengzhou, Henan, China
- Henan Key Laboratory of Kidney Disease and Immunology, Zhengzhou, Henan, China
- Henan Provincial Clinical Research Center for Kidney Disease, Zhengzhou, Henan, China
| | - Meihao Wu
- Department of Nephrology, Henan Provincial People's Hospital; People's Hospital of Zhengzhou University, People's Hospital of Henan University, Zhengzhou, Henan, China
- Henan Key Laboratory of Kidney Disease and Immunology, Zhengzhou, Henan, China
- Henan Provincial Clinical Research Center for Kidney Disease, Zhengzhou, Henan, China
| | - Shengfeng Wan
- Department of Nephrology, Henan Provincial People's Hospital; People's Hospital of Zhengzhou University, People's Hospital of Henan University, Zhengzhou, Henan, China
- Henan Key Laboratory of Kidney Disease and Immunology, Zhengzhou, Henan, China
- Henan Provincial Clinical Research Center for Kidney Disease, Zhengzhou, Henan, China
| | - Yan Zheng
- Department of Nephrology, Henan Provincial People's Hospital; People's Hospital of Zhengzhou University, People's Hospital of Henan University, Zhengzhou, Henan, China
- Henan Key Laboratory of Kidney Disease and Immunology, Zhengzhou, Henan, China
- Henan Provincial Clinical Research Center for Kidney Disease, Zhengzhou, Henan, China
| | - Xiaojing Jiao
- Department of Nephrology, Henan Provincial People's Hospital; People's Hospital of Zhengzhou University, People's Hospital of Henan University, Zhengzhou, Henan, China
- Henan Key Laboratory of Kidney Disease and Immunology, Zhengzhou, Henan, China
- Henan Provincial Clinical Research Center for Kidney Disease, Zhengzhou, Henan, China
| | - Lei Yan
- Department of Nephrology, Henan Provincial People's Hospital; People's Hospital of Zhengzhou University, People's Hospital of Henan University, Zhengzhou, Henan, China
- Henan Key Laboratory of Kidney Disease and Immunology, Zhengzhou, Henan, China
- Henan Provincial Clinical Research Center for Kidney Disease, Zhengzhou, Henan, China
| | - Huixia Cao
- Department of Nephrology, Henan Provincial People's Hospital; People's Hospital of Zhengzhou University, People's Hospital of Henan University, Zhengzhou, Henan, China
- Henan Key Laboratory of Kidney Disease and Immunology, Zhengzhou, Henan, China
- Henan Provincial Clinical Research Center for Kidney Disease, Zhengzhou, Henan, China
| | - Leiyi Yang
- Department of Cardiopulmonary Bypass, Henan Provincial People's Hospital; Department of Cardiopulmonary Bypass of Central China Fuwai Hospital, Central China Fuwai Hospital of Zhengzhou University, Zhengzhou, Henan, China
| | - Fengmin Shao
- Department of Nephrology, Henan Provincial People's Hospital; People's Hospital of Zhengzhou University, People's Hospital of Henan University, Zhengzhou, Henan, China
- Henan Key Laboratory of Kidney Disease and Immunology, Zhengzhou, Henan, China
- Henan Provincial Clinical Research Center for Kidney Disease, Zhengzhou, Henan, China
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3
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Li XC, Wang CH, Leite APO, Zhuo JL. Intratubular, Intracellular, and Mitochondrial Angiotensin II/AT 1 (AT1a) Receptor/NHE3 Signaling Plays a Critical Role in Angiotensin II-Induced Hypertension and Kidney Injury. Front Physiol 2021; 12:702797. [PMID: 34408663 PMCID: PMC8364949 DOI: 10.3389/fphys.2021.702797] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Accepted: 05/24/2021] [Indexed: 12/14/2022] Open
Abstract
Hypertension is well recognized to be the most important risk factor for cardiovascular diseases, stroke, and end-stage kidney failure. A quarter of the world’s adult populations and 46% of the US adults develop hypertension and currently require antihypertensive treatments. Only 50% of hypertensive patients are responsive to current antihypertensive drugs, whereas remaining patients may continue to develop cardiovascular, stroke, and kidney diseases. The mechanisms underlying the poorly controlled hypertension remain incompletely understood. Recently, we have focused our efforts to uncover additional renal mechanisms, pathways, and therapeutic targets of poorly controlled hypertension and target organ injury using novel animal models or innovative experimental approaches. Specifically, we studied and elucidated the important roles of intratubular, intracellular, and mitochondrial angiotensin II (Ang II) system in the development of Ang II-dependent hypertension. The objectives of this invited article are to review and discuss our recent findings that (a) circulating and intratubular Ang II is taken up by the proximal tubules via the (AT1) AT1a receptor-dependent mechanism, (b) intracellular administration of Ang II in proximal tubule cells or adenovirus-mediated overexpression of an intracellular Ang II fusion protein selectively in the mitochonria of the proximal tubules induces blood pressure responses, and (c) genetic deletion of AT1 (AT1a) receptors or the Na+/H+ exchanger 3 selectively in the proximal tubules decreases basal blood pressure and attenuates Ang II-induced hypertension. These studies provide a new perspective into the important roles of the intratubular, intracellular, and mitochondrial angiotensin II/AT1 (AT1a) receptor signaling in Ang II-dependent hypertensive kidney diseases.
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Affiliation(s)
- Xiao Chun Li
- Tulane Hypertension and Renal Center of Excellence, Department of Physiology, Tulane University School of Medicine,New Orleans, LA, United States
| | - Chih-Hong Wang
- Tulane Hypertension and Renal Center of Excellence, Department of Physiology, Tulane University School of Medicine,New Orleans, LA, United States
| | - Ana Paula Oliveira Leite
- Tulane Hypertension and Renal Center of Excellence, Department of Physiology, Tulane University School of Medicine,New Orleans, LA, United States
| | - Jia Long Zhuo
- Tulane Hypertension and Renal Center of Excellence, Department of Physiology, Tulane University School of Medicine,New Orleans, LA, United States
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4
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Matsuda J, Takahashi A, Takabatake Y, Sakai S, Minami S, Yamamoto T, Fujimura R, Namba-Hamano T, Yonishi H, Nakamura J, Kimura T, Kaimori JY, Matsui I, Takahashi M, Nakao M, Izumi Y, Bamba T, Matsusaka T, Niimura F, Yanagita M, Yoshimori T, Isaka Y. Metabolic effects of RUBCN/Rubicon deficiency in kidney proximal tubular epithelial cells. Autophagy 2020; 16:1889-1904. [PMID: 31944172 DOI: 10.1080/15548627.2020.1712107] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Macroautophagy/autophagy is a lysosomal degradation system which plays a protective role against kidney injury. RUBCN/Rubicon (RUN domain and cysteine-rich domain containing, Beclin 1-interacting protein) inhibits the fusion of autophagosomes and lysosomes. However, its physiological role in kidney proximal tubular epithelial cells (PTECs) remains uncertain. In the current study, we analyzed the phenotype of newly generated PTEC-specific rubcn-deficient (KO) mice. Additionally, we investigated the role of RUBCN in lipid metabolism using isolated rubcn-deficient PTECs. Although KO mice exhibited sustained high autophagic flux in PTECs, they were not protected from acute ischemic kidney injury. Unexpectedly, KO mice exhibited hallmark features of metabolic syndrome accompanied by expanded lysosomes containing multi-layered phospholipids in PTECs. RUBCN deficiency in cultured PTECs promoted the mobilization of phospholipids from cellular membranes to lysosomes via enhanced autophagy. Treatment of KO PTECs with oleic acid accelerated fatty acids transfer to mitochondria. Furthermore, KO PTECs promoted massive triglyceride accumulation in hepatocytes (BNL-CL2 cells) co-cultured in transwell, suggesting accelerated fatty acids efflux from the PTECs contributes to the metabolic syndrome in KO mice. This study shows that sustained high autophagic flux by RUBCN deficiency in PTECs leads to metabolic syndrome concomitantly with an accelerated mobilization of phospholipids from cellular membranes to lysosomes. Abbreviations: ABC: ATP binding cassette; ACADM: acyl-CoA dehydrogenase medium chain; ACTB: actin, beta; ATG: autophagy related; AUC: area under the curve; Baf: bafilomycin A1; BAT: brown adipose tissue; BODIPY: boron-dipyrromethene; BSA: bovine serum albumin; BW: body weight; CAT: chloramphenicol acetyltransferase; CM: complete medium; CPT1A: carnitine palmitoyltransferase 1a, liver; CQ: chloroquine; CTRL: control; EGFP: enhanced green fluorescent protein; CTSD: cathepsin D; EAT: epididymal adipose tissue; EGFR: epidermal growth factor receptor; EIF4EBP1: eukaryotic translation initiation factor 4E binding protein 1; FA: fatty acid; FBS: fetal bovine serum; GTT: glucose tolerance test; HE: hematoxylin and eosin; HFD: high-fat diet; I/R: ischemia-reperfusion; ITT: insulin tolerance test; KAP: kidney androgen regulated protein; KO: knockout; LAMP1: lysosomal associated membrane protein 1; LD: lipid droplet; LRP2: low density lipoprotein receptor related protein 2; MAP1LC3B: microtubule associated protein 1 light chain 3 beta; MAT: mesenteric adipose tissue; MS: mass spectrometry; MTOR: mechanistic target of rapamycin kinase; MTORC1: MTOR complex 1; NDRG1: N-myc downstream regulated 1; NDUFB5: NADH:ubiquinone oxidoreductase subunit B5; NEFA: non-esterified fatty acid; OA: oleic acid; OCT: optimal cutting temperature; ORO: Oil Red O; PAS: Periodic-acid Schiff; PFA: paraformaldehyde; PIK3C3: phosphatidylinositol 3-kinase catalytic subunit type 3; PPARA: peroxisome proliferator activated receptor alpha; PPARGC1A: PPARG coactivator 1 alpha; PTEC: proximal tubular epithelial cell; RAB7A: RAB7A, member RAS oncogene family; RPS6: ribosomal protein S6; RPS6KB1: ribosomal protein S6 kinase B1; RT: reverse transcription; RUBCN: rubicon autophagy regulator; SAT: subcutaneous adipose tissue; SFC: supercritical fluid chromatography; SQSTM1: sequestosome 1; SREBF1: sterol regulatory element binding transcription factor 1; SV-40: simian virus-40; TFEB: transcription factor EB; TG: triglyceride; TS: tissue specific; TUNEL: terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling; UN: urea nitrogen; UQCRB: ubiquinol-cytochrome c reductase binding protein; UVRAG: UV radiation resistance associated; VPS: vacuolar protein sorting; WAT: white adipose tissue.
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Affiliation(s)
- Jun Matsuda
- Department of Nephrology, Osaka University Graduate School of Medicine , Osaka, Japan
| | - Atsushi Takahashi
- Department of Nephrology, Osaka University Graduate School of Medicine , Osaka, Japan
| | - Yoshitsugu Takabatake
- Department of Nephrology, Osaka University Graduate School of Medicine , Osaka, Japan
| | - Shinsuke Sakai
- Department of Nephrology, Osaka University Graduate School of Medicine , Osaka, Japan
| | - Satoshi Minami
- Department of Nephrology, Osaka University Graduate School of Medicine , Osaka, Japan
| | - Takeshi Yamamoto
- Department of Nephrology, Osaka University Graduate School of Medicine , Osaka, Japan
| | - Ryuta Fujimura
- Department of Nephrology, Osaka University Graduate School of Medicine , Osaka, Japan
| | - Tomoko Namba-Hamano
- Department of Nephrology, Osaka University Graduate School of Medicine , Osaka, Japan
| | - Hiroaki Yonishi
- Department of Nephrology, Osaka University Graduate School of Medicine , Osaka, Japan
| | - Jun Nakamura
- Department of Nephrology, Osaka University Graduate School of Medicine , Osaka, Japan
| | - Tomonori Kimura
- Department of Nephrology, Osaka University Graduate School of Medicine , Osaka, Japan.,Reverse Translational Project, Center for Rare Disease Research, National Institute of Biomedical Innovation, Health and Nutrition (NIBIOHN) , Osaka, Japan
| | - Jun-Ya Kaimori
- Department of Advanced Technology for Transplantation, Osaka University Graduate School of Medicine , Osaka, Japan
| | - Isao Matsui
- Department of Nephrology, Osaka University Graduate School of Medicine , Osaka, Japan
| | - Masatomo Takahashi
- Division of Metabolomics, Medical Institute of Bioregulation, Kyushu University , Fukuoka, Japan
| | - Motonao Nakao
- Division of Metabolomics, Medical Institute of Bioregulation, Kyushu University , Fukuoka, Japan
| | - Yoshihiro Izumi
- Division of Metabolomics, Medical Institute of Bioregulation, Kyushu University , Fukuoka, Japan
| | - Takeshi Bamba
- Division of Metabolomics, Medical Institute of Bioregulation, Kyushu University , Fukuoka, Japan
| | - Taiji Matsusaka
- Institute of Medical Science and Department of Basic Sciences, Tokai University School of Medicine , Isehara, Japan
| | - Fumio Niimura
- Department of Pediatrics, Tokai University School of Medicine , Isehara, Japan
| | - Motoko Yanagita
- Department of Nephrology, Kyoto University Graduate School of Medicine , Kyoto, Japan.,Institute for the Advanced Study of Human Biology (ASHBi), Kyoto University , Kyoto, Japan
| | - Tamotsu Yoshimori
- Department of Genetics, Osaka University Graduate School of Medicine , Osaka, Japan
| | - Yoshitaka Isaka
- Department of Nephrology, Osaka University Graduate School of Medicine , Osaka, Japan
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5
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Suzuki C, Tanida I, Oliva Trejo JA, Kakuta S, Uchiyama Y. Autophagy Deficiency in Renal Proximal Tubular Cells Leads to an Increase in Cellular Injury and Apoptosis under Normal Fed Conditions. Int J Mol Sci 2019; 21:ijms21010155. [PMID: 31881660 PMCID: PMC6982095 DOI: 10.3390/ijms21010155] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 12/20/2019] [Accepted: 12/23/2019] [Indexed: 12/11/2022] Open
Abstract
Renal proximal tubular epithelial cells are significantly damaged during acute kidney injury. Renal proximal tubular cell-specific autophagy-deficient mice show increased sensitivity against renal injury, while showing few pathological defects under normal fed conditions. Considering that autophagy protects the proximal tubular cells from acute renal injury, it is reasonable to assume that autophagy contributes to the maintenance of renal tubular cells under normal fed conditions. To clarify this possibility, we generated a knock out mouse model which lacks Atg7, a key autophagosome forming enzyme, in renal proximal tubular cells (Atg7flox/flox;KAP-Cre+). Analysis of renal tissue from two months old Atg7flox/flox;KAP-Cre+ mouse revealed an accumulation of LC3, binding protein p62/sequestosome 1 (a selective substrate for autophagy), and more interestingly, Kim-1, a biomarker for early kidney injury, in the renal proximal tubular cells under normal fed conditions. TUNEL (TdT-mediated dUTP Nick End Labeling)-positive cells were also detected in the autophagy-deficient renal tubular cells. Analysis of renal tissue from Atg7flox/flox;KAP-Cre+ mice at different age points showed that tubular cells positive for p62 and Kim-1 continually increase in number in an age-dependent manner. Ultrastructural analysis of tubular cells from Atg7flox/flox;KAP-Cre+ revealed the presence of intracellular inclusions and abnormal structures. These results indicated that autophagy-deficiency in the renal proximal epithelial tubular cells leads to an increase in injured cells in the kidney even under normal fed conditions.
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Affiliation(s)
- Chigure Suzuki
- Department of Cellular and Molecular Neuropathology, Juntendo University Graduate School of Medicine, Bunkyo-Ku, Tokyo 113-8421, Japan; (C.S.); (J.A.O.T.); (S.K.)
- Department of Cellular and Molecular Pharmacology, Juntendo University Graduate School of Medicine, Bunkyo-Ku, Tokyo 113-8421, Japan
| | - Isei Tanida
- Department of Cellular and Molecular Neuropathology, Juntendo University Graduate School of Medicine, Bunkyo-Ku, Tokyo 113-8421, Japan; (C.S.); (J.A.O.T.); (S.K.)
- Correspondence: (I.T.); (Y.U.); Tel.: +81-3-3813-3111 (I.T. & Y.U.)
| | - Juan Alejandro Oliva Trejo
- Department of Cellular and Molecular Neuropathology, Juntendo University Graduate School of Medicine, Bunkyo-Ku, Tokyo 113-8421, Japan; (C.S.); (J.A.O.T.); (S.K.)
| | - Soichiro Kakuta
- Department of Cellular and Molecular Neuropathology, Juntendo University Graduate School of Medicine, Bunkyo-Ku, Tokyo 113-8421, Japan; (C.S.); (J.A.O.T.); (S.K.)
- Laboratory of Morphology and Image Analysis, Biomedical Research Center, Juntendo University Graduate School of Medicine, Bunkyo-Ku, Tokyo 113-8421, Japan
| | - Yasuo Uchiyama
- Department of Cellular and Molecular Neuropathology, Juntendo University Graduate School of Medicine, Bunkyo-Ku, Tokyo 113-8421, Japan; (C.S.); (J.A.O.T.); (S.K.)
- Correspondence: (I.T.); (Y.U.); Tel.: +81-3-3813-3111 (I.T. & Y.U.)
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6
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Barros CC, Schadock I, Sihn G, Rother F, Xu P, Popova E, Lapidus I, Plehm R, Heuser A, Todiras M, Bachmann S, Alenina N, Araujo RC, Pesquero JB, Bader M. Chronic Overexpression of Bradykinin in Kidney Causes Polyuria and Cardiac Hypertrophy. Front Med (Lausanne) 2018; 5:338. [PMID: 30560131 PMCID: PMC6287039 DOI: 10.3389/fmed.2018.00338] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2018] [Accepted: 11/16/2018] [Indexed: 01/06/2023] Open
Abstract
Acute intra-renal infusion of bradykinin increases diuresis and natriuresis via inhibition of vasopressin activity. However, the consequences of chronically increased bradykinin in the kidneys have not yet been studied. A new transgenic animal model producing an excess of bradykinin by proximal tubular cells (KapBK rats) was generated and submitted to different salt containing diets to analyze changes in blood pressure and other cardiovascular parameters, urine excretion, and composition, as well as levels and expression of renin-angiotensin system components. Despite that KapBK rats excrete more urine and sodium, they have similar blood pressure as controls with the exception of a small increase in systolic blood pressure (SBP). However, they present decreased renal artery blood flow, increased intrarenal expression of angiotensinogen, and decreased mRNA expression of vasopressin V1A receptor (AVPR1A), suggesting a mechanism for the previously described reduction of renal vasopressin sensitivity by bradykinin. Additionally, reduced heart rate variability (HRV), increased cardiac output and frequency, and the development of cardiac hypertrophy are the main chronic effects observed in the cardiovascular system. In conclusion: (1) the transgenic KapBK rat is a useful model for studying chronic effects of bradykinin in kidney; (2) increased renal bradykinin causes changes in renin angiotensin system regulation; (3) decreased renal vasopressin sensitivity in KapBK rats is related to decreased V1A receptor expression; (4) although increased renal levels of bradykinin causes no changes in mean arterial pressure (MAP), it causes reduction in HRV, augmentation in cardiac frequency and output and consequently cardiac hypertrophy in rats after 6 months of age.
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Affiliation(s)
- Carlos C Barros
- Department of Nutrition, Federal University of Pelotas, Pelotas, Brazil
| | - Ines Schadock
- Department of Biophysics, Federal University of São Paulo, São Paulo, Brazil.,Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Gabin Sihn
- Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | | | - Ping Xu
- Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Elena Popova
- Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Irina Lapidus
- Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Ralph Plehm
- Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Arnd Heuser
- Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Mihail Todiras
- Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | | | - Natalia Alenina
- Max Delbrück Center for Molecular Medicine, Berlin, Germany.,Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Ronaldo C Araujo
- Department of Biophysics, Federal University of São Paulo, São Paulo, Brazil
| | - Joao B Pesquero
- Department of Biophysics, Federal University of São Paulo, São Paulo, Brazil
| | - Michael Bader
- Max Delbrück Center for Molecular Medicine, Berlin, Germany.,Charite-University Medicine, Berlin, Germany.,Federal University of Minas Gerais, Belo Horizonte, Brazil.,Berlin Institute of Health (BIH), Berlin, Germany.,German Center for Cardiovascular Research (DZHK), Partner Site Berlin, Berlin, Germany.,Institute for Biology, University of Lübeck, Lübeck, Germany
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7
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Intratubular and intracellular renin-angiotensin system in the kidney: a unifying perspective in blood pressure control. Clin Sci (Lond) 2018; 132:1383-1401. [PMID: 29986878 DOI: 10.1042/cs20180121] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Revised: 06/05/2018] [Accepted: 06/13/2018] [Indexed: 12/18/2022]
Abstract
The renin-angiotensin system (RAS) is widely recognized as one of the most important vasoactive hormonal systems in the physiological regulation of blood pressure and the development of hypertension. This recognition is derived from, and supported by, extensive molecular, cellular, genetic, and pharmacological studies on the circulating (tissue-to-tissue), paracrine (cell-to-cell), and intracrine (intracellular, mitochondrial, nuclear) RAS during last several decades. Now, it is widely accepted that circulating and local RAS may act independently or interactively, to regulate sympathetic activity, systemic and renal hemodynamics, body salt and fluid balance, and blood pressure homeostasis. However, there remains continuous debate with respect to the specific sources of intratubular and intracellular RAS in the kidney and other tissues, the relative contributions of the circulating RAS to intratubular and intracellular RAS, and the roles of intratubular compared with intracellular RAS to the normal control of blood pressure or the development of angiotensin II (ANG II)-dependent hypertension. Based on a lecture given at the recent XI International Symposium on Vasoactive Peptides held in Horizonte, Brazil, this article reviews recent studies using mouse models with global, kidney- or proximal tubule-specific overexpression (knockin) or deletion (knockout) of components of the RAS or its receptors. Although much knowledge has been gained from cell- and tissue-specific transgenic or knockout models, a unifying and integrative approach is now required to better understand how the circulating and local intratubular/intracellular RAS act independently, or with other vasoactive systems, to regulate blood pressure, cardiovascular and kidney function.
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8
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Nishiyama A, Kobori H. Independent regulation of renin-angiotensin-aldosterone system in the kidney. Clin Exp Nephrol 2018; 22:1231-1239. [PMID: 29600408 PMCID: PMC6163102 DOI: 10.1007/s10157-018-1567-1] [Citation(s) in RCA: 74] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2017] [Accepted: 03/21/2018] [Indexed: 01/13/2023]
Abstract
Renin-angiotensin-aldosterone system (RAAS) plays important roles in regulating renal hemodynamics and functions, as well as in the pathophysiology of hypertension and renal disease. In the kidney, angiotensin II (Ang II) production is controlled by independent multiple mechanisms. Ang II is compartmentalized in the renal interstitial fluid with much higher concentrations than those existing in the circulation. Inappropriate activation of the intrarenal RAAS is an important contributor to the pathogenesis of hypertension and renal injury. It has been revealed that intrarenal Ang II levels are predominantly regulated by angiotensinogen and therefore, urinary angiotensinogen could be a biomarker for intrarenal Ang II generation. In addition, recent studies have demonstrated that aldosterone contributes to the progression of renal injury via direct actions on glomerular podocytes, mesangial cells, proximal tubular cells and tubulo-interstitial fibroblasts through the activation of locally expressed mineralocorticoid receptor. Thus, it now appears that intrarenal RAAS is independently regulated and its inappropriate activation contributes to the pathogenesis of the development of hypertension and renal disease. This short review article will focus on the independent regulation of the intrarenal RAAS with an emphasis on the specific role of angiotensinogen.
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Affiliation(s)
- Akira Nishiyama
- Department of Pharmacology, Faculty of Medicine, Kagawa University, 1750-1 Miki-cho, Kita-gun, Kagawa, 761-0793, Japan.
| | - Hiroyuki Kobori
- Departments of Pharmacology and Nephrology, Faculty of Medicine, International University of Health and Welfare, Narita, Japan
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Ramkumar N, Stuart D, Calquin M, Wang S, Niimura F, Matsusaka T, Kohan DE. Possible role for nephron-derived angiotensinogen in angiotensin-II dependent hypertension. Physiol Rep 2016; 4:4/1/e12675. [PMID: 26755736 PMCID: PMC4760401 DOI: 10.14814/phy2.12675] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The role of intranephron angiotensinogen (AGT) in blood pressure (BP) regulation is not fully understood. Previous studies showed that proximal tubule‐specific overexpression of AGT increases BP, whereas proximal tubule‐specific deletion of AGT did not alter BP. The latter study may not have completely eliminated nephron AGT production; in addition, BP was only assessed on a normal salt diet. To evaluate this issue in greater detail, we developed mice with inducible nephron‐wide AGT deletion. Mice were generated which were hemizygous for the Pax8‐rtTA and LC‐1 transgenes and homozygous for loxP‐flanked AGT alleles to achieve nephron‐wide AGT disruption after doxycycline induction. Compared to controls, AGT knockout (KO) mice demonstrated markedly reduced renal AGT immunostaining, mRNA, and protein levels; unexpectedly AGT KO mice had reduced AGT mRNA levels in the liver along with 50% reduction in plasma AGT levels. BP was significantly lower in the AGT KO mice compared to controls fed a normal, low, or high Na+ intake, with the highest BP reduction on a low Na+ diet. Regardless of Na+ intake, AGT KO mice had higher plasma renin concentration (PRC) and markedly reduced urinary AGT levels compared to controls. Following angiotensin‐II (Ang‐II) infusion, AGT KO mice demonstrated an attenuated hypertensive response despite similar suppression of PRC in the two groups. Taken together, these data suggest that nephron‐derived AGT may be involved in Ang‐II‐dependent hypertension, however, a clear role for nephron‐derived AGT in physiological BP regulation remains to be determined.
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Affiliation(s)
- Nirupama Ramkumar
- Division of Nephrology and Hypertension, University of Utah Health Sciences Center, Salt Lake City, Utah
| | - Deborah Stuart
- Division of Nephrology and Hypertension, University of Utah Health Sciences Center, Salt Lake City, Utah
| | - Matias Calquin
- Division of Nephrology and Hypertension, University of Utah Health Sciences Center, Salt Lake City, Utah
| | - Shuping Wang
- Division of Nephrology and Hypertension, University of Utah Health Sciences Center, Salt Lake City, Utah
| | - Fumio Niimura
- Institute of Medical Science, Tokai University, Isehara, Japan
| | - Taiji Matsusaka
- Institute of Medical Science, Tokai University, Isehara, Japan
| | - Donald E Kohan
- Division of Nephrology and Hypertension, University of Utah Health Sciences Center, Salt Lake City, Utah Veterans Affairs Medical Center, Salt Lake City, Utah
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Ide N, Olauson H, Sato T, Densmore MJ, Wang H, Hanai JI, Larsson TE, Lanske B. In vivo evidence for a limited role of proximal tubular Klotho in renal phosphate handling. Kidney Int 2016; 90:348-362. [DOI: 10.1016/j.kint.2016.04.009] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Revised: 03/29/2016] [Accepted: 04/14/2016] [Indexed: 01/11/2023]
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Saigusa T. Suppressing kidney angiotensinogen in blood pressure regulation. Physiol Rep 2016; 4:4/3/e12704. [PMID: 26847848 PMCID: PMC4758934 DOI: 10.14814/phy2.12704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Affiliation(s)
- Takamitsu Saigusa
- Division of Nephrology, Medical University of South Carolina, Charleston, South Carolina
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Lo CS, Shi Y, Chang SY, Abdo S, Chenier I, Filep JG, Ingelfinger JR, Zhang SL, Chan JSD. Overexpression of heterogeneous nuclear ribonucleoprotein F stimulates renal Ace-2 gene expression and prevents TGF-β1-induced kidney injury in a mouse model of diabetes. Diabetologia 2015; 58:2443-54. [PMID: 26232095 PMCID: PMC4572079 DOI: 10.1007/s00125-015-3700-y] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Accepted: 06/26/2015] [Indexed: 01/09/2023]
Abstract
AIMS/HYPOTHESIS We investigated whether heterogeneous nuclear ribonucleoprotein F (hnRNP F) stimulates renal ACE-2 expression and prevents TGF-β1 signalling, TGF-β1 inhibition of Ace-2 gene expression and induction of tubulo-fibrosis in an Akita mouse model of type 1 diabetes. METHODS Adult male Akita transgenic (Tg) mice overexpressing specifically hnRNP F in their renal proximal tubular cells (RPTCs) were studied. Non-Akita littermates and Akita mice served as controls. Immortalised rat RPTCs stably transfected with plasmid containing either rat Hnrnpf cDNA or rat Ace-2 gene promoter were also studied. RESULTS Overexpression of hnRNP F attenuated systemic hypertension, glomerular filtration rate, albumin/creatinine ratio, urinary angiotensinogen (AGT) and angiotensin (Ang) II levels, renal fibrosis and profibrotic gene (Agt, Tgf-β1, TGF-β receptor II [Tgf-βrII]) expression, stimulated anti-profibrotic gene (Ace-2 and Ang 1-7 receptor [MasR]) expression, and normalised urinary Ang 1-7 level in Akita Hnrnpf-Tg mice as compared with Akita mice. In vitro, hnRNP F overexpression stimulated Ace-2 gene promoter activity, mRNA and protein expression, and attenuated Agt, Tgf-β1 and Tgf-βrII gene expression. Furthermore, hnRNP F overexpression prevented TGF-β1 signalling and TGF-β1 inhibition of Ace-2 gene expression. CONCLUSIONS/INTERPRETATION These data demonstrate that hnRNP F stimulates Ace-2 gene transcription, prevents TGF-β1 inhibition of Ace-2 gene transcription and induction of kidney injury in diabetes. HnRNP F may be a potential target for treating hypertension and renal fibrosis in diabetes.
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Affiliation(s)
- Chao-Sheng Lo
- Centre de recherche, Centre hospitalier de l'Université de Montréal (CRCHUM) - Tour Viger Pavillon R, Université de Montréal, 900 Saint-Denis Street, Montreal, QC, H2X 0A9, Canada
| | - Yixuan Shi
- Centre de recherche, Centre hospitalier de l'Université de Montréal (CRCHUM) - Tour Viger Pavillon R, Université de Montréal, 900 Saint-Denis Street, Montreal, QC, H2X 0A9, Canada
| | - Shiao-Ying Chang
- Centre de recherche, Centre hospitalier de l'Université de Montréal (CRCHUM) - Tour Viger Pavillon R, Université de Montréal, 900 Saint-Denis Street, Montreal, QC, H2X 0A9, Canada
| | - Shaaban Abdo
- Centre de recherche, Centre hospitalier de l'Université de Montréal (CRCHUM) - Tour Viger Pavillon R, Université de Montréal, 900 Saint-Denis Street, Montreal, QC, H2X 0A9, Canada
| | - Isabelle Chenier
- Centre de recherche, Centre hospitalier de l'Université de Montréal (CRCHUM) - Tour Viger Pavillon R, Université de Montréal, 900 Saint-Denis Street, Montreal, QC, H2X 0A9, Canada
| | - Janos G Filep
- Research Centre, Maisonneuve-Rosemont Hospital, Université de Montréal, Montreal, QC, Canada
| | - Julie R Ingelfinger
- Pediatric Nephrology Unit, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Shao-Ling Zhang
- Centre de recherche, Centre hospitalier de l'Université de Montréal (CRCHUM) - Tour Viger Pavillon R, Université de Montréal, 900 Saint-Denis Street, Montreal, QC, H2X 0A9, Canada.
| | - John S D Chan
- Centre de recherche, Centre hospitalier de l'Université de Montréal (CRCHUM) - Tour Viger Pavillon R, Université de Montréal, 900 Saint-Denis Street, Montreal, QC, H2X 0A9, Canada.
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Majid DSA, Prieto MC, Navar LG. Salt-Sensitive Hypertension: Perspectives on Intrarenal Mechanisms. Curr Hypertens Rev 2015; 11:38-48. [PMID: 26028244 DOI: 10.2174/1573402111666150530203858] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Revised: 04/22/2015] [Accepted: 04/24/2015] [Indexed: 12/12/2022]
Abstract
Salt sensitive hypertension is characterized by increases in blood pressure in response to increases in dietary salt intake and is associated with an enhanced risk of cardiovascular and renal morbidity. Although researchers have sought for decades to understand how salt sensitivity develops in humans, the mechanisms responsible for the increases in blood pressure in response to high salt intake are complex and only partially understood. Until now, scientists have been unable to explain why some individuals are salt sensitive and others are salt resistant. Although a central role for the kidneys in the development of salt sensitivity and hypertension has been generally accepted, it is also recognized that hypertension is of multifactorial origin and a variety of factors can induce, or prevent, blood pressure responsiveness to the manipulation of salt intake. Excess salt intake in susceptible persons may also induce inappropriate central and sympathetic nervous system responses and increase the production of intrarenal angiotensin II, catecholamines and other factors such as oxidative stress and inflammatory cytokines. One key factor is the concomitant inappropriate or paradoxical activation of the intrarenal renin-angiotensin system, by high salt intake. This is reflected by the increases in urinary angiotensinogen during high salt intake in salt sensitive models. A complex interaction between neuroendocrine factors and the kidney may underlie the propensity for some individuals to retain salt and develop salt-dependent hypertension. In this review, we focus mainly on the renal contributions that provide the mechanistic links between chronic salt intake and the development of hypertension.
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Affiliation(s)
- Dewan S A Majid
- Department of Physiology, SL39, Tulane University School of Medicine, 1430 Tulane Avenue, New Orleans, LA 70112, USA.
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Megyesi J, Tarcsafalvi A, Li S, Hodeify R, Seng NSHL, Portilla D, Price PM. Increased expression of p21WAF1/CIP1 in kidney proximal tubules mediates fibrosis. Am J Physiol Renal Physiol 2015; 308:F122-30. [PMID: 25428126 PMCID: PMC4340262 DOI: 10.1152/ajprenal.00489.2014] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Accepted: 11/18/2014] [Indexed: 01/06/2023] Open
Abstract
Tissue fibrosis is a major cause of death in developed countries. It commonly occurs after either acute or chronic injury and affects diverse organs, including the heart, liver, lung, and kidney. Using the renal ablation model of chronic kidney disease, we previously found that the development of progressive renal fibrosis was dependent on p21(WAF1/Cip1) expression; the genetic knockout of the p21 gene greatly alleviated this disease. In the present study, we expanded on this observation and report that fibrosis induced by two different acute injuries to the kidney is also dependent on p21. In addition, when p21 expression was restricted only to the proximal tubule, fibrosis after injury was induced in the whole organ. One molecular fibrogenic switch we describe is transforming growth factor-β induction, which occurred in vivo and in cultured kidney cells exposed to adenovirus expressing p21. Our data suggests that fibrosis is p21 dependent and that preventing p21 induction after stress could be a novel therapeutic target.
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Affiliation(s)
- Judit Megyesi
- Division of Nephrology, University of Arkansas for Medical Sciences, Little Rock, Arkansas; Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, Arkansas; and Central Arkansas Veterans Healthcare System, Little Rock, Arkansas
| | - Adel Tarcsafalvi
- Division of Nephrology, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Shenyang Li
- Division of Nephrology, University of Arkansas for Medical Sciences, Little Rock, Arkansas; Central Arkansas Veterans Healthcare System, Little Rock, Arkansas
| | - Rawad Hodeify
- Division of Nephrology, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Nang San Hti Lar Seng
- Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, Arkansas; and
| | - Didier Portilla
- Division of Nephrology, University of Arkansas for Medical Sciences, Little Rock, Arkansas; Central Arkansas Veterans Healthcare System, Little Rock, Arkansas
| | - Peter M Price
- Division of Nephrology, University of Arkansas for Medical Sciences, Little Rock, Arkansas; Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, Arkansas; and Central Arkansas Veterans Healthcare System, Little Rock, Arkansas
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15
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Jang HR, Jeon J, Park JH, Lee JE, Huh W, Oh HY, Kim YG. Clinical relevance of urinary angiotensinogen and renin as potential biomarkers in patients with overt proteinuria. Transl Res 2014; 164:400-10. [PMID: 24929205 DOI: 10.1016/j.trsl.2014.05.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2013] [Revised: 05/18/2014] [Accepted: 05/20/2014] [Indexed: 01/13/2023]
Abstract
Urinary angiotensinogen (AGT) and renin have been reported to reflect the intrarenal renin-angiotensin system (RAS) activity. However, the adequacy and clinical significance of these markers have not been evaluated in overtly proteinuric patients. In patients with biopsy-proven glomerulonephritis, plasma and urinary AGT and renin were analyzed. A cohort of 75 patients treated with RAS inhibitors was followed for 1 year. Among the 207 patients, 105 had subnephrotic and 102 had nephrotic-range proteinuria. Mean age, estimated glomerular filtration rate (eGFR), and urinary protein-to-creatinine ratio (P/Cr) of all patients were 48 years, 79.7 mL/min/1.73 m(2), and 5.66 mg/mg, respectively. Both natural logarithm of urinary AGT/creatinine (ln [urinary AGT/Cr]) and ln (urinary renin/Cr) showed positive correlations with urinary P/Cr. There was a positive correlation between ln (urinary AGT/Cr) and ln (urinary renin/Cr). Ln (urinary renin/Cr) was not affected by ln (plasma renin) regardless of the degree of proteinuria. The treatment response to RAS inhibitors was greatest in patients with high urinary AGT and renin. However, the predictive value of those parameters was no longer present when the values were adjusted by the degree of proteinuria. Ln (urinary renin/Cr) and initial eGFR were independently associated with the changes in renal function for 1 year. Ln (urinary AGT/Cr) was associated with persistent overt proteinuria after 1 year. Our study suggests that urinary renin may be a better marker in heavy proteinuria, and the treatment response to RAS inhibitors may be enhanced in patients with high urinary renin and AGT. Further studies will be necessary to explore the value of urinary AGT and renin.
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Affiliation(s)
- Hye Ryoun Jang
- Nephrology Division, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Junseok Jeon
- Nephrology Division, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Ji Hyeon Park
- Nephrology Division, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Jung Eun Lee
- Nephrology Division, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Wooseong Huh
- Nephrology Division, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Ha Young Oh
- Nephrology Division, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
| | - Yoon-Goo Kim
- Nephrology Division, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
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16
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Droguett A, Krall P, Burgos ME, Valderrama G, Carpio D, Ardiles L, Rodriguez-Diez R, Kerr B, Walz K, Ruiz-Ortega M, Egido J, Mezzano S. Tubular overexpression of gremlin induces renal damage susceptibility in mice. PLoS One 2014; 9:e101879. [PMID: 25036148 PMCID: PMC4103765 DOI: 10.1371/journal.pone.0101879] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Accepted: 06/12/2014] [Indexed: 11/18/2022] Open
Abstract
A growing number of patients are recognized worldwide to have chronic kidney disease. Glomerular and interstitial fibrosis are hallmarks of renal progression. However, fibrosis of the kidney remains an unresolved challenge, and its molecular mechanisms are still not fully understood. Gremlin is an embryogenic gene that has been shown to play a key role in nephrogenesis, and its expression is generally low in the normal adult kidney. However, gremlin expression is elevated in many human renal diseases, including diabetic nephropathy, pauci-immune glomerulonephritis and chronic allograft nephropathy. Several studies have proposed that gremlin may be involved in renal damage by acting as a downstream mediator of TGF-β. To examine the in vivo role of gremlin in kidney pathophysiology, we generated seven viable transgenic mouse lines expressing human gremlin (GREM1) specifically in renal proximal tubular epithelial cells under the control of an androgen-regulated promoter. These lines demonstrated 1.2- to 200-fold increased GREM1 expression. GREM1 transgenic mice presented a normal phenotype and were without proteinuria and renal function involvement. In response to the acute renal damage cause by folic acid nephrotoxicity, tubule-specific GREM1 transgenic mice developed increased proteinuria after 7 and 14 days compared with wild-type treated mice. At 14 days tubular lesions, such as dilatation, epithelium flattening and hyaline casts, with interstitial cell infiltration and mild fibrosis were significantly more prominent in transgenic mice than wild-type mice. Tubular GREM1 overexpression was correlated with the renal upregulation of profibrotic factors, such as TGF-β and αSMA, and with increased numbers of monocytes/macrophages and lymphocytes compared to wild-type mice. Taken together, our results suggest that GREM1-overexpressing mice have an increased susceptibility to renal damage, supporting the involvement of gremlin in renal damage progression. This transgenic mouse model could be used as a new tool for enhancing the knowledge of renal disease progression.
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Affiliation(s)
- Alejandra Droguett
- Division Nephrology, School of Medicine, Universidad Austral de Chile, Valdivia, Chile
| | - Paola Krall
- Division Nephrology, School of Medicine, Universidad Austral de Chile, Valdivia, Chile
| | - M. Eugenia Burgos
- Division Nephrology, School of Medicine, Universidad Austral de Chile, Valdivia, Chile
| | - Graciela Valderrama
- Division Nephrology, School of Medicine, Universidad Austral de Chile, Valdivia, Chile
| | - Daniel Carpio
- Hystopathology Division, School of Medicine, Universidad Austral de Chile, Valdivia, Chile
| | - Leopoldo Ardiles
- Division Nephrology, School of Medicine, Universidad Austral de Chile, Valdivia, Chile
| | - Raquel Rodriguez-Diez
- Cellular Biology in Renal Diseases Laboratory, Universidad Autónoma Madrid, Madrid, Spain
| | | | | | - Marta Ruiz-Ortega
- Cellular Biology in Renal Diseases Laboratory, Universidad Autónoma Madrid, Madrid, Spain
| | - Jesus Egido
- Cellular Biology in Renal Diseases Laboratory, Universidad Autónoma Madrid, Madrid, Spain
| | - Sergio Mezzano
- Division Nephrology, School of Medicine, Universidad Austral de Chile, Valdivia, Chile
- * E-mail:
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Carey RM, Padia SH. Role of angiotensin AT(2) receptors in natriuresis: Intrarenal mechanisms and therapeutic potential. Clin Exp Pharmacol Physiol 2014; 40:527-34. [PMID: 23336117 DOI: 10.1111/1440-1681.12059] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Revised: 01/16/2013] [Accepted: 01/16/2013] [Indexed: 01/11/2023]
Abstract
The renin-angiotensin system is a coordinated hormonal cascade critical for the regulation of blood pressure (BP) and kidney function. Angiotensin (Ang) II, the major angiotensin effector peptide, binds to two major receptors, namely AT1 and AT2 receptors. The AT1 receptors engender antinatriuresis and raise BP, whereas AT2 receptors oppose these effects, inducing natriuresis and reducing BP. There is high AT2 receptor expression in the adult kidney, especially in the proximal tubule. In AT2 receptor-null mice, long-term AngII infusion results in pressor and antinatriuretic hypersensivivity compared with responses in wild-type mice. The major endogenous receptor ligand for AT2 receptor-mediated natriuretic responses appears to be des-aspartyl(1) -AngII (AngIII) instead of AngII. Recent studies have demonstrated that AngII requires metabolism to AngIII by aminopeptidase A to induce natriuresis and that inhibition of aminopeptidase N increases intrarenal AngIII and augments AngIII-induced natriuresis. The renal dopaminergic system is another important natriuretic pathway. Renal proximal tubule the D1 and D5 receptor subtypes (D1 -like receptors (D1LIKE R)) control approximately 50% of basal sodium excretion. Recently, we have found that natriuresis induced by proximal tubule D1LIKE R requires AT2 receptor activation and that D1LIKE R stimulation induces recruitment of AT2 receptors to the apical plasma membrane via a cAMP-dependent mechanism. Initial studies using the potent AT2 receptor non-peptide agonist Compound 21 demonstrate natriuresis in both the presence and absence of AT1 receptor blockade, indicating the therapeutic potential of this compound in fluid-retaining states and hypertension.
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Affiliation(s)
- Robert M Carey
- Division of Endocrinology and Metabolism, Department of Medicine, University of Virginia Health System, Charlottesville, VA 22908, USA.
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Kobori H, Kamiyama M, Harrison-Bernard LM, Navar LG. Cardinal role of the intrarenal renin-angiotensin system in the pathogenesis of diabetic nephropathy. J Investig Med 2013. [PMID: 23266706 DOI: 10.231/jim.0b013e31827c28bb] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Diabetes mellitus is one of the most prevalent diseases and is associated with increased incidence of structural and functional derangements in the kidneys, eventually leading to end-stage renal disease in a significant fraction of afflicted individuals. The renoprotective effects of renin-angiotensin system (RAS) blockade have been established; however, the mechanistic pathways have not been fully elucidated. In this review article, the cardinal role of an activated RAS in the pathogenesis of diabetic nephropathy (DN) is discussed with a focus on 4 themes: (1) introduction to RAS cascade, (2) intrarenal RAS in diabetes, (3) clinical outcomes of RAS blockade in DN, and (4) potential of urinary angiotensinogen as an early biomarker of intrarenal RAS status in DN. This review article provides a mechanistic rational supporting the hypothesis that an activated intrarenal RAS contributes to the pathogenesis of DN and that urinary angiotensinogen levels provide an index of intrarenal RAS activity.
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Affiliation(s)
- Hiroyuki Kobori
- Department of Physiology, and Hypertension and Renal Center of Excellence, Tulane University Health Sciences Center, New Orleans, LA, USA.
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Tanaka S, Ishii A, Ohtaki H, Shioda S, Yoshida T, Numazawa S. Activation of microglia induces symptoms of Parkinson's disease in wild-type, but not in IL-1 knockout mice. J Neuroinflammation 2013; 10:143. [PMID: 24289537 PMCID: PMC4220804 DOI: 10.1186/1742-2094-10-143] [Citation(s) in RCA: 93] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Accepted: 11/07/2013] [Indexed: 11/26/2022] Open
Abstract
Background Parkinson’s disease (PD) is an age-related progressive neurodegenerative disorder caused by selective loss of dopaminergic neurons from the substantia nigra (SN) to the striatum. The initial factor that triggers neurodegeneration is unknown; however, inflammation has been demonstrated to be significantly involved in the progression of PD. The present study was designed to investigate the role of the pro-inflammatory cytokine interleukin-1 (IL-1) in the activation of microglia and the decline of motor function using IL-1 knockout (KO) mice. Methods Lipopolysaccharide (LPS) was stereotaxically injected into the SN of mice brains as a single dose or a daily dose for 5 days (5 mg/2 ml/injection, bilaterally). Animal behavior was assessed with the rotarod test at 2 hr and 8, 15 and 22 days after the final LPS injection. Results LPS treatment induced the activation of microglia, as demonstrated by production of IL-1β and tumor necrosis factor (TNF) α as well as a change in microglial morphology. The number of cells immunoreactive for 4-hydroxynonenal (4HNE) and nitrotyrosine (NT), which are markers for oxidative insults, increased in the SN, and impairment of motor function was observed after the subacute LPS treatment. Cell death and aggregation of α-synuclein were observed 21 and 30 days after the final LPS injection, respectively. Behavioral deficits were observed in wild-type and TNFα KO mice, but IL-1 KO mice behaved normally. Tyrosine hydroxylase (TH) gene expression was attenuated by LPS treatment in wild-type and TNFα KO mice but not in IL-1 KO mice. Conclusions The subacute injection of LPS into the SN induces PD-like pathogenesis and symptoms in mice that mimic the progressive changes of PD including the aggregation of α-synuclein. LPS-induced dysfunction of motor performance was accompanied by the reduced gene expression of TH. These findings suggest that activation of microglia by LPS causes functional changes such as dopaminergic neuron attenuation in an IL-1-dependent manner, resulting in PD-like behavioral impairment.
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Affiliation(s)
- Sachiko Tanaka
- Department of Pharmacology, Toxicology and Therapeutics, Division of Toxicology, School of Pharmacy, Showa University, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo 142-8555, Japan.
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Abstract
PURPOSE OF REVIEW Although the existence of a complete intrarenal renin-angiotensin system is now well established, its role in modulating tubule sodium transport and blood pressure is incompletely understood. Several recent studies have shed light on one component of the system, proximal tubule-derived angiotensinogen (AGT). This review discusses the synthesis, regulation and function of AGT in the proximal tubule. RECENT FINDINGS Under normal sodium intake, AGT within the S1 and S2 segments of the proximal tubule may derive from the systemic circulation, whereas the S3 segment synthesizes AGT. Urinary AGT likely primarily reflects proximal tubule-derived AGT. Proximal tubule AGT synthesis is regulated by high Na intake, angiotensin-II and inflammatory cytokines. Transgenic expression of mouse AGT in the proximal tubule causes hypertension. Overexpression of rat AGT in the proximal tubule leads to hypertension, enhanced reactive oxygen species generation via NADPH oxidase, tubular apoptosis and tubulointerstitial fibrosis; these effects can be mitigated by catalase overexpression. SUMMARY Proximal tubule-derived AGT has the potential to modulate blood pressure and sodium balance, and promote renal injury. Interactions with the systemic renin-angiotensin system may influence the role of proximal tubule-derived AGT in the kidney.
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21
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Li XC, Zhuo JL. Proximal tubule-dominant transfer of AT(1a) receptors induces blood pressure responses to intracellular angiotensin II in AT(1a) receptor-deficient mice. Am J Physiol Regul Integr Comp Physiol 2013; 304:R588-98. [PMID: 23427083 PMCID: PMC3627953 DOI: 10.1152/ajpregu.00338.2012] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2012] [Accepted: 02/18/2013] [Indexed: 02/08/2023]
Abstract
The role of intracellular ANG II in proximal tubules of the kidney remains poorly understood. We tested the hypothesis that proximal tubule-dominant transfer of AT(1a) receptors in the cortex mediates intracellular ANG II-induced blood pressure responses in AT(1a) receptor-deficient (Agtr1a-/-) mice. A GFP-tagged AT(1a) receptor, AT(1a)R/GFP, and an enhanced cyan fluorescent intracellular ANG II fusion protein, ECFP/ANG II, were expressed in proximal tubules of Agtr1a-/- mouse kidneys via the adenoviral transfer using a sodium and glucose cotransporter 2 promoter. Transfer of AT(1a)R/GFP alone or with ECFP/ANG II induced proximal tubule-dominant expression of AT(1a)R/GFP and/or ECFP/ANG II with a peak response at 2 wk. No significant AT(1a)R/GFP and/or ECFP/ANG II expression was observed in the glomeruli, medulla, or extrarenal tissues. Transfer of AT(1a)R/GFP alone, but not ECFP/ANG II, increased systolic blood pressure by 12 ± 2 mmHg by day 14 (n = 9, P < 0.01). However, cotransfer of AT(1a)R/GFP with ECFP/ANG II increased blood pressure by 18 ± 2 mmHg (n = 12, P < 0.01). Twenty-four hour urinary sodium excretion was decreased by day 7 with proximal tubule-dominant transfer of AT(1a)R/GFP alone (P < 0.01) or with AT(1a)R/GFP and ECFP/ANG II cotransfer (P < 0.01). These responses were associated with twofold increases in phosphorylated ERK1/2, lysate, and membrane NHE-3 proteins in freshly isolated proximal tubules (P < 0.01). By contrast, transfer of control CMV-GFP (a recombinant human adenovirus type 5 expresses enhanced green fluorescent protein under the control of a cytomegalovirus (CMV) promoter), ECFP/ANG II, or a scrambled control ECFP/ANG IIc alone in proximal tubules had no effect on all indices. These results suggest that AT(1a) receptors and intracellular ANG II in proximal tubules of the kidney play an important physiological role in blood pressure regulation.
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MESH Headings
- Angiotensin II/biosynthesis
- Angiotensin II/pharmacology
- Animals
- Blood Pressure/drug effects
- Blood Pressure/physiology
- Blotting, Western
- Dependovirus
- Drinking/physiology
- Electrolytes/urine
- Enzyme-Linked Immunosorbent Assay
- Genetic Vectors
- Green Fluorescent Proteins/genetics
- Kidney Tubules, Proximal/drug effects
- Kidney Tubules, Proximal/metabolism
- Low Density Lipoprotein Receptor-Related Protein-2/biosynthesis
- Low Density Lipoprotein Receptor-Related Protein-2/genetics
- MAP Kinase Signaling System
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Receptor, Angiotensin, Type 1/genetics
- Receptor, Angiotensin, Type 1/metabolism
- Receptor, Angiotensin, Type 1/physiology
- Sodium-Glucose Transporter 2/metabolism
- Sodium-Hydrogen Exchanger 3
- Sodium-Hydrogen Exchangers/biosynthesis
- Sodium-Hydrogen Exchangers/genetics
- Vasoconstrictor Agents/pharmacology
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Affiliation(s)
- Xiao C. Li
- Laboratory of Receptor and Signal Transduction, Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, Mississippi
| | - Jia L. Zhuo
- Laboratory of Receptor and Signal Transduction, Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, Mississippi
- Center of Excellence for Cardiovascular-Renal Research, University of Mississippi Medical Center, Jackson, Mississippi; and
- Division of Nephrology, Department of Internal Medicine, University of Mississippi Medical Center, Jackson, Mississippi
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22
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Kobori H, Kamiyama M, Harrison-Bernard LM, Navar LG. Cardinal Role of the Intrarenal Renin-Angiotensin System in the Pathogenesis of Diabetic Nephropathy. J Investig Med 2013; 61:256-264. [DOI: 10.2310/jim.0b013e31827c28bb] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/30/2023]
Abstract
Diabetes mellitus is one of the most prevalent diseases and is associated with increased incidence of structural and functional derangements in the kidneys, eventually leading to end-stage renal disease in a significant fraction of afflicted individuals. The renoprotective effects of renin-angiotensin system (RAS) blockade have been established; however, the mechanistic pathways have not been fully elucidated. In this review article, the cardinal role of an activated RAS in the pathogenesis of diabetic nephropathy (DN) is discussed with a focus on 4 themes: (1) introduction to RAS cascade, (2) intrarenal RAS in diabetes, (3) clinical outcomes of RAS blockade in DN, and (4) potential of urinary angiotensinogen as an early biomarker of intrarenal RAS status in DN. This review article provides a mechanistic rational supporting the hypothesis that an activated intrarenal RAS contributes to the pathogenesis of DN and that urinary angiotensinogen levels provide an index of intrarenal RAS activity.
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Affiliation(s)
- Hiroyuki Kobori
- *Department of Physiology, and Hypertension and Renal Center of Excellence, Tulane University Health Sciences Center
| | - Masumi Kamiyama
- *Department of Physiology, and Hypertension and Renal Center of Excellence, Tulane University Health Sciences Center
| | | | - L. Gabriel Navar
- *Department of Physiology, and Hypertension and Renal Center of Excellence, Tulane University Health Sciences Center
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23
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Prieto-Carrasquero MC, Botros FT, Kobori H, Navar LG. Collecting Duct Renin: A major player in Angiotensin II-dependent Hypertension. ACTA ACUST UNITED AC 2012; 3:96-104. [PMID: 20046983 DOI: 10.1016/j.jash.2008.11.003] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Recently, the focus of interest on the role of the renin angiotensin system in the pathophysiology of hypertension has shifted towards greater emphasis on new developments in local renin angiotensin systems in specific tissues. We have focused our recent investigations on the role of the intrarenal-intratubular RAS in hypertension. All of the components needed for angiotensin II generation are present within the various compartments in the kidney. This brief review is focused on recent evidence that inappropriate activation of renin in distal nephron segments, by acting on angiotensinogen generated in the proximal tubule cells and delivered to the distal nephron may contribute to increased distal intrarenal angiotensin II formation, sodium retention and development and progression of hypertension.
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Affiliation(s)
- Minolfa C Prieto-Carrasquero
- Department of Physiology and Tulane Renal Hypertension Center, Tulane University, School of Medicine, New Orleans, LA, 70112
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24
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Lo CS, Chang SY, Chenier I, Filep JG, Ingelfinger JR, Zhang SL, Chan JS. Heterogeneous nuclear ribonucleoprotein F suppresses angiotensinogen gene expression and attenuates hypertension and kidney injury in diabetic mice. Diabetes 2012; 61:2597-608. [PMID: 22664958 PMCID: PMC3447919 DOI: 10.2337/db11-1349] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
We investigated the impact of heterogeneous nuclear ribonucleoprotein F (hnRNP F) overexpression on angiotensinogen (Agt) gene expression, hypertension, and renal proximal tubular cell (RPTC) injury in high-glucose milieu both in vivo and in vitro. Diabetic Akita transgenic (Tg) mice specifically overexpressing hnRNP F in their RPTCs were created, and the effects on systemic hypertension, Agt gene expression, renal hypertrophy, and interstitial fibrosis were studied. We also examined immortalized rat RPTCs stably transfected with control plasmid or plasmid containing hnRNP F cDNA in vitro. The results showed that hnRNP F overexpression attenuated systemic hypertension, suppressed Agt and transforming growth factor-β1 (TGF-β1) gene expression, and reduced urinary Agt and angiotensin II levels, renal hypertrophy, and glomerulotubular fibrosis in Akita hnRNP F-Tg mice. In vitro, hnRNP F overexpression prevented the high-glucose stimulation of Agt and TGF-β1 mRNA expression and cellular hypertrophy in RPTCs. These data suggest that hnRNP F plays a modulatory role and can ameliorate hypertension, renal hypertrophy, and interstitial fibrosis in diabetes. The underlying mechanism is mediated, at least in part, via the suppression of intrarenal Agt gene expression in vivo. hnRNP F may be a potential target in the treatment of hypertension and kidney injury in diabetes.
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Affiliation(s)
- Chao-Sheng Lo
- Centre de Recherche du Centre Hospitalier de l’Université de Montréal, Université de Montréal, Hôtel-Dieu Hospital, Montreal, Quebec, Canada
| | - Shiao-Ying Chang
- Centre de Recherche du Centre Hospitalier de l’Université de Montréal, Université de Montréal, Hôtel-Dieu Hospital, Montreal, Quebec, Canada
| | - Isabelle Chenier
- Centre de Recherche du Centre Hospitalier de l’Université de Montréal, Université de Montréal, Hôtel-Dieu Hospital, Montreal, Quebec, Canada
| | - Janos G. Filep
- Research Centre, Maisonneuve-Rosemont Hospital, Montreal, Quebec, Canada
| | - Julie R. Ingelfinger
- Pediatric Nephrology Unit, Massachusetts General Hospital, Boston, Massachusetts
| | - Shao Ling Zhang
- Centre de Recherche du Centre Hospitalier de l’Université de Montréal, Université de Montréal, Hôtel-Dieu Hospital, Montreal, Quebec, Canada
| | - John S.D. Chan
- Centre de Recherche du Centre Hospitalier de l’Université de Montréal, Université de Montréal, Hôtel-Dieu Hospital, Montreal, Quebec, Canada
- Corresponding author: John S.D. Chan,
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25
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Kobori H, Urushihara M. Augmented intrarenal and urinary angiotensinogen in hypertension and chronic kidney disease. Pflugers Arch 2012; 465:3-12. [PMID: 22918624 DOI: 10.1007/s00424-012-1143-6] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Revised: 08/03/2012] [Accepted: 08/06/2012] [Indexed: 12/22/2022]
Abstract
Activated intrarenal renin-angiotensin system plays a cardinal role in the pathogenesis of hypertension and chronic kidney disease. Angiotensinogen is the only known substrate for renin, which is the rate-limiting enzyme of the renin-angiotensin system. Because the levels of angiotensinogen are close to the Michaelis-Menten constant values for renin, angiotensinogen levels as well as renin levels can control the renin-angiotensin system activity, and thus, upregulation of angiotensinogen leads to an increase in the angiotensin II levels and ultimately increases blood pressure. Recent studies using experimental animal models have documented the involvement of angiotensinogen in the intrarenal renin-angiotensin system activation and development of hypertension. Enhanced intrarenal angiotensinogen mRNA and/or protein levels were observed in experimental models of hypertension and chronic kidney disease, supporting the important roles of angiotensinogen in the development and the progression of hypertension and chronic kidney disease. Urinary excretion rates of angiotensinogen provide a specific index of the intrarenal renin-angiotensin system status in angiotensin II-infused rats. Also, a direct quantitative method has been developed recently to measure urinary angiotensinogen using human angiotensinogen enzyme-linked immunosorbent assay. These data prompted us to measure urinary angiotensinogen in patients with hypertension and chronic kidney disease, and investigate correlations with clinical parameters. This short article will focus on the role of the augmented intrarenal angiotensinogen in the pathophysiology of hypertension and chronic kidney disease. In addition, the potential of urinary angiotensinogen as a novel biomarker of the intrarenal renin-angiotensin system status in hypertension and chronic kidney disease will be also discussed.
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Affiliation(s)
- Hiroyuki Kobori
- Department of Physiology, Tulane University Health Sciences Center, 1430 Tulane Avenue, #SL39, New Orleans, LA 70112-2699, USA.
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26
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Ying J, Stuart D, Hillas E, Gociman BR, Ramkumar N, Lalouel JM, Kohan DE. Overexpression of mouse angiotensinogen in renal proximal tubule causes salt-sensitive hypertension in mice. Am J Hypertens 2012; 25:684-9. [PMID: 22378037 DOI: 10.1038/ajh.2012.16] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
BACKGROUND The role of proximal tubule (PT) angiotensinogen (AGT) in modulating blood pressure has previously been examined using mice expressing PT human AGT and human renin, or rat AGT. These animals are hypertensive; however, the question remains whether alterations in mouse PT AGT alone affects arterial pressure. METHODS Mouse AGT cDNA was knocked-in to the endogenous kidney androgen protein (KAP) gene using an internal ribosomal entry site (IRES)-based strategy. RESULTS The KAP-mAGT animals showed kidney-specific KAP-AGT mRNA expression; renal in situ hybridization detected KAP-AGT mRNA only in PT. Urinary AGT was markedly increased in KAP-mAGT mice. On a high Na diet, radiotelemetric arterial pressure showed a systolic pressure elevation; no significant difference in arterial pressure was observed on a normal diet. Plasma renin concentration (PRC) was reduced in KAP-mAGT animals given a high Na diet, but was not different between mouse lines during normal Na intake. Plasma AGT concentration was not altered by overexpression of PT mouse AGT. CONCLUSIONS In summary, PT overexpression of mouse AGT leads to salt-sensitive hypertension without recruitment of the systemic renin-angiotensin system.
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27
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Castrop H. Angiotensin receptor-associated proteins: local modulators of the renin–angiotensin system. Pflugers Arch 2012; 465:111-9. [DOI: 10.1007/s00424-012-1113-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2012] [Revised: 04/30/2012] [Accepted: 05/02/2012] [Indexed: 01/11/2023]
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28
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Chen D, Coffman TM. The Kidney and Hypertension: Lessons From Mouse Models. Can J Cardiol 2012; 28:305-10. [DOI: 10.1016/j.cjca.2012.01.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2011] [Revised: 01/04/2012] [Accepted: 01/04/2012] [Indexed: 11/28/2022] Open
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29
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Matsusaka T, Niimura F, Shimizu A, Pastan I, Saito A, Kobori H, Nishiyama A, Ichikawa I. Liver angiotensinogen is the primary source of renal angiotensin II. J Am Soc Nephrol 2012; 23:1181-9. [PMID: 22518004 DOI: 10.1681/asn.2011121159] [Citation(s) in RCA: 192] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Angiotensin II content in the kidney is much higher than in the plasma, and it increases more in kidney diseases through an uncertain mechanism. Because the kidney abundantly expresses angiotensinogen mRNA, transcriptional dysregulation of angiotensinogen within the kidney is one potential cause of increased renal angiotensin II in the setting of disease. Here, we observed that kidney-specific angiotensinogen knockout mice had levels of renal angiotensinogen protein and angiotensin II that were similar to those levels of control mice. In contrast, liver-specific knockout of angiotensinogen nearly abolished plasma and renal angiotensinogen protein and renal tissue angiotensin II. Immunohistochemical analysis in mosaic proximal tubules of megalin knockout mice revealed that angiotensinogen protein was incorporated selectively in megalin-intact cells of the proximal tubule, indicating that the proximal tubule reabsorbs filtered angiotensinogen through megalin. Disruption of the filtration barrier in a transgenic mouse model of podocyte-selective injury increased renal angiotensin II content and markedly increased both tubular and urinary angiotensinogen protein without an increase in renal renin activity, supporting the dependency of renal angiotensin II generation on filtered angiotensinogen. Taken together, these data suggest that liver-derived angiotensinogen is the primary source of renal angiotensinogen protein and angiotensin II. Furthermore, an abnormal increase in the permeability of the glomerular capillary wall to angiotensinogen, which characterizes proteinuric kidney diseases, enhances the synthesis of renal angiotensin II.
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Affiliation(s)
- Taiji Matsusaka
- Department of Internal Medicine, Tokai University School of Medicine, Isehara, Kanagawa, Japan.
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30
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Lau GJ, Godin N, Maachi H, Lo CS, Wu SJ, Zhu JX, Brezniceanu ML, Chénier I, Fragasso-Marquis J, Lattouf JB, Ethier J, Filep JG, Ingelfinger JR, Nair V, Kretzler M, Cohen CD, Zhang SL, Chan JS. Bcl-2-modifying factor induces renal proximal tubular cell apoptosis in diabetic mice. Diabetes 2012; 61:474-84. [PMID: 22210314 PMCID: PMC3266424 DOI: 10.2337/db11-0141] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
This study investigated the mechanisms underlying tubular apoptosis in diabetes by identifying proapoptotic genes that are differentially upregulated by reactive oxygen species in renal proximal tubular cells (RPTCs) in models of diabetes. Total RNAs isolated from renal proximal tubules (RPTs) of 20-week-old heterozygous db/m+, db/db, and db/db catalase (CAT)-transgenic (Tg) mice were used for DNA chip microarray analysis. Real-time quantitative PCR assays, immunohistochemistry, and mice rendered diabetic with streptozotocin were used to validate the proapoptotic gene expression in RPTs. Cultured rat RPTCs were used to confirm the apoptotic activity and regulation of proapoptotic gene expression. Additionally, studies in kidney tissues from patients with and without diabetes were used to confirm enhanced proapoptotic gene expression in RPTs. Bcl-2-modifying factor (Bmf) was differentially upregulated (P<0.01) in RPTs of db/db mice compared with db/m+ and db/db CAT-Tg mice and in RPTs of streptozotocin-induced diabetic mice in which insulin reversed this finding. In vitro, Bmf cDNA overexpression in rat RPTCs coimmunoprecipated with Bcl-2, enhanced caspase-3 activity, and promoted apoptosis. High glucose (25 mmol/L) induced Bmf mRNA expression in RPTCs, whereas rotenone, catalase, diphenylene iodinium, and apocynin decreased it. Knockdown of Bmf with small interfering RNA reduced high glucose-induced apoptosis in RPTCs. More important, enhanced Bmf expression was detected in RPTs of kidneys from patients with diabetes. These data demonstrate differential upregulation of Bmf in diabetic RPTs and suggest a potential role for Bmf in regulating RPTC apoptosis and tubular atrophy in diabetes.
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Affiliation(s)
- Garnet J. Lau
- Centre de recherche du Centre hospitalier de l’Université de Montréal (CRCHUM), Hôtel-Dieu Hospital, Université de Montréal, Montreal, Quebec, Canada
| | - Nicolas Godin
- Centre de recherche du Centre hospitalier de l’Université de Montréal (CRCHUM), Hôtel-Dieu Hospital, Université de Montréal, Montreal, Quebec, Canada
| | - Hasna Maachi
- Centre de recherche du Centre hospitalier de l’Université de Montréal (CRCHUM), Hôtel-Dieu Hospital, Université de Montréal, Montreal, Quebec, Canada
| | - Chao-Sheng Lo
- Centre de recherche du Centre hospitalier de l’Université de Montréal (CRCHUM), Hôtel-Dieu Hospital, Université de Montréal, Montreal, Quebec, Canada
| | - Shyh-Jong Wu
- Centre de recherche du Centre hospitalier de l’Université de Montréal (CRCHUM), Hôtel-Dieu Hospital, Université de Montréal, Montreal, Quebec, Canada
| | - Jian-Xin Zhu
- Centre de recherche du Centre hospitalier de l’Université de Montréal (CRCHUM), Hôtel-Dieu Hospital, Université de Montréal, Montreal, Quebec, Canada
| | - Marie-Luise Brezniceanu
- Centre de recherche du Centre hospitalier de l’Université de Montréal (CRCHUM), Hôtel-Dieu Hospital, Université de Montréal, Montreal, Quebec, Canada
| | - Isabelle Chénier
- Centre de recherche du Centre hospitalier de l’Université de Montréal (CRCHUM), Hôtel-Dieu Hospital, Université de Montréal, Montreal, Quebec, Canada
| | - Joelle Fragasso-Marquis
- Centre de recherche du Centre hospitalier de l’Université de Montréal (CRCHUM), Hôtel-Dieu Hospital, Université de Montréal, Montreal, Quebec, Canada
| | - Jean-Baptiste Lattouf
- Centre de recherche du Centre hospitalier de l’Université de Montréal (CRCHUM), Hôtel-Dieu Hospital, Université de Montréal, Montreal, Quebec, Canada
| | - Jean Ethier
- Centre de recherche du Centre hospitalier de l’Université de Montréal (CRCHUM), Hôtel-Dieu Hospital, Université de Montréal, Montreal, Quebec, Canada
| | - Janos G. Filep
- Research Centre, Maisonneuve-Rosemont Hospital, Montreal, Quebec, Canada
| | - Julie R. Ingelfinger
- Pediatric Nephrology Unit, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | - Viji Nair
- Nephrology/Internal Medicine, Center for Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, Michigan
| | - Matthias Kretzler
- Nephrology/Internal Medicine, Center for Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, Michigan
| | - Clemens D. Cohen
- Division of Nephrology, Institute of Physiology, University Hospital of Zurich, University of Zurich, Zurich, Switzerland
| | - Shao-Ling Zhang
- Centre de recherche du Centre hospitalier de l’Université de Montréal (CRCHUM), Hôtel-Dieu Hospital, Université de Montréal, Montreal, Quebec, Canada
| | - John S.D. Chan
- Centre de recherche du Centre hospitalier de l’Université de Montréal (CRCHUM), Hôtel-Dieu Hospital, Université de Montréal, Montreal, Quebec, Canada
- Corresponding author: John S.D. Chan,
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31
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Sigmund CD. Divergent mechanism regulating fluid intake and metabolism by the brain renin-angiotensin system. Am J Physiol Regul Integr Comp Physiol 2011; 302:R313-20. [PMID: 22049229 DOI: 10.1152/ajpregu.00575.2011] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The purpose of this review is two-fold. First, I will highlight recent advances in our understanding of the mechanisms regulating angiotensin II (ANG II) synthesis in the brain, focusing on evidence that renin is expressed in the brain and is expressed in two forms: a secreted form, which may catalyze extracellular ANG I generation from glial or neuronal angiotensinogen (AGT), and an intracellular form, which may generate intracellular ANG in neurons that may act as a neurotransmitter. Second, I will discuss recent studies that advance the concept that the renin-angiotensin system (RAS) in the brain not only is a potent regulator of blood pressure and fluid intake but may also regulate metabolism. The efferent pathways regulating the blood pressure/dipsogenic effects and the metabolic effects of elevated central RAS activity appear different, with the former being dependent upon the hypothalamic-pituitary-adrenal axis, and the latter being dependent upon an interaction between the brain and the systemic (or adipose) RAS.
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Affiliation(s)
- Curt D Sigmund
- Department of Pharmacology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, 52242, USA.
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32
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Matsuda H, Lavoie JL, Gaboury L, Hamet P, Tremblay J. HCaRG accelerates tubular repair after ischemic kidney injury. J Am Soc Nephrol 2011; 22:2077-89. [PMID: 21921141 DOI: 10.1681/asn.2010121265] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
The repair of the kidney after ischemia/reperfusion injury involves proliferation of proximal tubular epithelial cells as well as cell migration and differentiation. Immediately after reperfusion, expression of hypertension-related calcium-regulated gene (HCaRG/COMMD5) decreases, but its expression increases even higher than baseline during repair. HCaRG inhibits proliferation and accelerates wound healing and differentiation in cultured cells, but whether HCaRG can stimulate renal repair after ischemia/reperfusion injury is unknown. Here, transgenic mice overexpressing human HCaRG survived longer and recovered renal function faster than littermate controls after ischemia/reperfusion (64% versus 25% survival at 7 days). Proliferation of proximal tubular epithelial cells stopped earlier after ischemia/reperfusion injury, E-cadherin levels recovered more rapidly, and vimentin induction abated faster in transgenic mice. HCaRG overexpression also reduced macrophage infiltration and inflammation after injury. Taken together, these data suggest that HCaRG accelerates repair of renal proximal tubules by modulating cell proliferation of resident tubular epithelial cells and by facilitating redifferentiation.
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Affiliation(s)
- Hiroyuki Matsuda
- Centre de Recherche, Centre Hospitalier de l’Université de Montréal, Montréal, Québec, Canada
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33
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Li H, Weatherford ET, Davis DR, Keen HL, Grobe JL, Daugherty A, Cassis LA, Allen AM, Sigmund CD. Renal proximal tubule angiotensin AT1A receptors regulate blood pressure. Am J Physiol Regul Integr Comp Physiol 2011; 301:R1067-77. [PMID: 21753145 DOI: 10.1152/ajpregu.00124.2011] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
All components of the renin angiotensin system necessary for ANG II generation and action have been reported to be present in renal proximal convoluted tubules. Given the close relationship between renal sodium handling and blood pressure regulation, we hypothesized that modulating the action of ANG II specifically in the renal proximal tubules would alter the chronic level of blood pressure. To test this, we used a proximal tubule-specific, androgen-dependent, promoter construct (KAP2) to generate mice with either overexpression of a constitutively active angiotensin type 1A receptor transgene or depletion of endogenous angiotensin type 1A receptors. Androgen administration to female transgenic mice caused a robust induction of the transgene in the kidney and increased baseline blood pressure. In the receptor-depleted mice, androgen administration to females resulted in a Cre recombinase-mediated deletion of angiotensin type 1A receptors in the proximal tubule and reduced blood pressure. In contrast to the changes observed at baseline, there was no difference in the blood pressure response to a pressor dose of ANG II in either experimental model. These data, from two separate mouse models, provide evidence that ANG II signaling via the type 1A receptor in the renal proximal tubule is a regulator of systemic blood pressure under baseline conditions.
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Affiliation(s)
- Huiping Li
- Department of Internal Medicine, University of Iowa, Iowa City, Iowa 52242, USA
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34
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Zhuo JL, Li XC. New insights and perspectives on intrarenal renin-angiotensin system: focus on intracrine/intracellular angiotensin II. Peptides 2011; 32:1551-65. [PMID: 21699940 PMCID: PMC3137727 DOI: 10.1016/j.peptides.2011.05.012] [Citation(s) in RCA: 111] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/28/2011] [Revised: 05/05/2011] [Accepted: 05/09/2011] [Indexed: 02/06/2023]
Abstract
Although renin, the rate-limiting enzyme of the renin-angiotensin system (RAS), was first discovered by Robert Tigerstedt and Bergman more than a century ago, the research on the RAS still remains stronger than ever. The RAS, once considered to be an endocrine system, is now widely recognized as dual (circulating and local/tissue) or multiple hormonal systems (endocrine, paracrine and intracrine). In addition to the classical renin/angiotensin I-converting enzyme (ACE)/angiotensin II (Ang II)/Ang II receptor (AT₁/AT₂) axis, the prorenin/(Pro)renin receptor (PRR)/MAP kinase axis, the ACE2/Ang (1-7)/Mas receptor axis, and the Ang IV/AT₄/insulin-regulated aminopeptidase (IRAP) axis have recently been discovered. Furthermore, the roles of the evolving RAS have been extended far beyond blood pressure control, aldosterone synthesis, and body fluid and electrolyte homeostasis. Indeed, novel actions and underlying signaling mechanisms for each member of the RAS in physiology and diseases are continuously uncovered. However, many challenges still remain in the RAS research field despite of more than one century's research effort. It is expected that the research on the expanded RAS will continue to play a prominent role in cardiovascular, renal and hypertension research. The purpose of this article is to review the progress recently being made in the RAS research, with special emphasis on the local RAS in the kidney and the newly discovered prorenin/PRR/MAP kinase axis, the ACE2/Ang (1-7)/Mas receptor axis, the Ang IV/AT₄/IRAP axis, and intracrine/intracellular Ang II. The improved knowledge of the expanded RAS will help us better understand how the classical renin/ACE/Ang II/AT₁ receptor axis, extracellular and/or intracellular origin, interacts with other novel RAS axes to regulate blood pressure and cardiovascular and kidney function in both physiological and diseased states.
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Affiliation(s)
- Jia L Zhuo
- Laboratory of Receptor and Signal Transduction, Department of Pharmacology and Toxicology, the University of Mississippi Medical Center, Jackson, MS 39216-4505, USA.
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Kimura T, Takabatake Y, Takahashi A, Kaimori JY, Matsui I, Namba T, Kitamura H, Niimura F, Matsusaka T, Soga T, Rakugi H, Isaka Y. Autophagy protects the proximal tubule from degeneration and acute ischemic injury. J Am Soc Nephrol 2011; 22:902-13. [PMID: 21493778 DOI: 10.1681/asn.2010070705] [Citation(s) in RCA: 370] [Impact Index Per Article: 28.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Autophagy is a bulk protein degradation system that likely plays an important role in normal proximal tubule function and recovery from acute ischemic kidney injury. Using conditional Atg5 gene deletion to eliminate autophagy in the proximal tubule, we determined whether autophagy prevents accumulation of damaged proteins and organelles with aging and ischemic renal injury. Autophagy-deficient cells accumulated deformed mitochondria and cytoplasmic inclusions, leading to cellular hypertrophy and eventual degeneration not observed in wildtype controls. In autophagy-deficient mice, I/R injury increased proximal tubule cell apoptosis with accumulation of p62 and ubiquitin positive cytoplasmic inclusions. Compared with control animals, autophagy-deficient mice exhibited significantly greater elevations in serum urea nitrogen and creatinine. These data suggest that autophagy maintains proximal tubule cell homeostasis and protects against ischemic injury. Enhancing autophagy may provide a novel therapeutic approach to minimize acute kidney injury and slow CKD progression.
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Affiliation(s)
- Tomonori Kimura
- Department of Geriatric Medicine and Nephrology, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
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Li XC, Cook JL, Rubera I, Tauc M, Zhang F, Zhuo JL. Intrarenal transfer of an intracellular fluorescent fusion of angiotensin II selectively in proximal tubules increases blood pressure in rats and mice. Am J Physiol Renal Physiol 2011; 300:F1076-88. [PMID: 21307128 DOI: 10.1152/ajprenal.00329.2010] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The present study tested the hypothesis that intrarenal adenoviral transfer of an intracellular cyan fluorescent fusion of angiotensin II (ECFP/ANG II) selectively in proximal tubules of the kidney increases blood pressure by activating AT(1) (AT(1a)) receptors. Intrarenal transfer of ECFP/ANG II was induced in the superficial cortex of rat and mouse kidneys, and the sodium and glucose cotransporter 2 (sglt2) promoter was used to drive ECFP/ANG II expression selectively in proximal tubules. Intrarenal transfer of ECFP/ANG II induced a time-dependent, proximal tubule-selective expression of ECFP/ANG II in the cortex, which peaked at 2 wk and was sustained for 4 wk. ECFP/ANG II expression was low in the glomeruli and the entire medulla and was absent in the contralateral kidney or extrarenal tissues. At its peak of expression in proximal tubules at day 14, ANG II was increased by twofold in the kidney (P < 0.01) and more than threefold in proximal tubules (P < 0.01), but remained unchanged in plasma or urine. Systolic blood pressure was increased in ECFP/ANG II-transferred rats by 28 ± 6 mmHg (P < 0.01), whereas fractional sodium excretion was decreased by 20% (P < 0.01) and fractional lithium excretion was reduced by 24% (P < 0.01). These effects were blocked by losartan and prevented in AT(1a) knockout mice. Transfer of a scrambled ECFP/ANG IIc had no effects on blood pressure, kidney, and proximal tubule ANG II, or sodium excretion. These results provide evidence that proximal tubule-selective transfer of an intracellular ANG II fusion protein increases blood pressure by activating AT(1a) receptors and increasing sodium reabsorption in proximal tubules.
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Affiliation(s)
- Xiao C Li
- Laboratory of Receptor and Signal Transduction, Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, 39216-4505, USA
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Acres OW, Satou R, Navar LG, Kobori H. Contribution of a nuclear factor-kappaB binding site to human angiotensinogen promoter activity in renal proximal tubular cells. Hypertension 2011; 57:608-13. [PMID: 21282554 DOI: 10.1161/hypertensionaha.110.165464] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Intrarenal angiotensinogen (AGT) is expressed highly in renal proximal tubular cells (RPTCs) and contributes to the regulation of intrarenal angiotensin II levels. Inhibition of nuclear factor (NF)-κB suppressed human (h)AGT expression in human RPTCs. However, the presence and localization of an NF-κB binding site in the hAGT promoter region have not been determined. Therefore, this study was performed to demonstrate that an NF-κB binding site in the hAGT promoter region contributes to hAGT promoter activity in human RPTCs. The hAGT promoter region was cloned from -4358 to +122 and deletion analysis was performed. A possible NF-κB binding site was removed from the hAGT promoter region (M1) and mutated (M2). Human RPTCs were transfected, and hAGT promoter activity was determined by luciferase assay. The identity of DNA binding proteins from binding assays were determined by Western blot. Progressive 5'-end deletions demonstrated removal of a distal promoter element in hAGT_-2414/+122 reduced promoter activity (0.61 ± 0.12, ratio to hAGT_-4358/+122). Inhibition of NF-κB suppressed promoter activity in hAGT_-4358/+122 (0.51 ± 0.14, ratio to control) and hAGT_-3681/+122 (0.48 ± 0.06, ratio to control) but not in the construct without the NF-κB binding site. Promoter activity was reduced in the domain mutants M1 (0.57 ± 0.08, ratio to hAGT_-4358/+122) and M2 (0.61 ± 0.16, ratio to hAGT_-4358/+122). DNA binding levels of NF-κB protein were reduced in M1. These data demonstrate the functional importance of an NF-κB binding site in the hAGT promoter region, which contributes to hAGT promoter activity in human RPTCs.
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Affiliation(s)
- Omar W Acres
- Department of Medicine and Physiology, Tulane University Health Sciences Center, New Orleans, LA 70112-2699, USA
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Urushihara M, Kobori H. Angiotensinogen Expression Is Enhanced in the Progression of Glomerular Disease. ACTA ACUST UNITED AC 2011; 2:378-387. [PMID: 22247811 DOI: 10.4236/ijcm.2011.24064] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Intrarenal renin-angiotensin system (RAS) activation plays a critical role in the development and progression of renal injury. In the kidney, all of the RAS components are present and intrarenal angiotensin II (Ang II) is formed by multiple independent mechanisms. Angiotensinogen (AGT) is the only known substrate for renin that is a rate-limiting enzyme of the RAS. Recently, enhanced intrarenal AGT levels have been shown to reflect the intrarenal RAS status in hypertension, chronic glomerular disease and diabetic nephropathy. In this review, we focus on AGT expression of the diseased glomeruli in the progression of glomerular disease. An anti-glomerular basement membrane nephritis rat model developed progressive proteinuria and glomerular crescent formation, accompanied by increased macrophage infiltration and glomerular expression of AGT and Ang II. The addition of Ang II type 1 receptor blocker to CC-chemokine recaptor 2 antagonist markedly attenuated the induction of macrophage infiltration, AGT and Ang II, and reduced glomerular crescent formation. Next, the levels of glomerular AGT expression and marker of reactive oxygen species in Zucker diabetic fatty (ZDF) obese rats were higher than those in ZDF lean rats. Hydrogen peroxide (H(2)O(2)) induced an increase in the AGT expression in primary rat mesangial cells. Furthermore, the H(2)O(2)-induced upregulation of AGT was inhibited by a mitogen-activated protein kinase kinase and a c-Jun N-terminal kinase inhibitor. These data suggest the potential contribution of enhanced AGT expression in glomeruli to the intrarenal RAS activation for the development of glomerular disease.
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Affiliation(s)
- Maki Urushihara
- Department of Physiology, and Hypertension and Renal Center of Excellence Tulane University Health Sciences Center, New Orleans, USA
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Abstract
BACKGROUND The Bogalusa Heart Study is a long-term study on cardiovascular disease and has followed a biracial (black/white) population from childhood. Risk factor data pertaining to many patients have been collected over 35 years, and the time course of hypertension has been documented by repeated examinations and measurements. Considerable sex and racial differences have been found to be related to cardiovascular disease. Urinary angiotensinogen (UAGT) is a novel biomarker for the intrarenal activity of the renin-angiotensin system in hypertension and kidney disease. We aimed to determine the relationship of UAGT with traditional cardiovascular disease risk factors in asymptomatic young adults in this biracial population. METHOD We recruited 251 individuals and collected a single random spot urine sample from each one. Because UAGT is significantly increased in diabetic patients and the use of antihypertensive drugs affects UAGT levels, we excluded patients who had diabetes, who were receiving antihypertensive treatment, or both. Consequently, 190 participants were included for this analysis. RESULTS UAGT levels did not differ with race or sex, but were significantly correlated with SBP (r = +0.23, P = 0.0015) and DBP (r = +0.24, P = 0.0012). Moreover, high correlations were shown in men, especially in black men (SBP, r = +0.85, P = 0.0005 and DBP, r = +0.72, P = 0.0079). Thus, UAGT is correlated with blood pressure in men, even when they do not show overt proteinuria or albuminuria. CONCLUSION The biomarker, UAGT, may facilitate the identification of individuals that are at increased risk for the development of hypertension and early asymptomatic renal disease.
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Catalase overexpression prevents hypertension and tubular apoptosis in angiotensinogen transgenic mice. Kidney Int 2010; 77:1086-97. [DOI: 10.1038/ki.2010.63] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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41
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Huang XJ, Wang X, Ihsan A, Liu Q, Xue XJ, Su SJ, Yang CH, Zhou W, Yuan ZH. Interactions of NADPH oxidase, renin-angiotensin-aldosterone system and reactive oxygen species in mequindox-mediated aldosterone secretion in Wistar rats. Toxicol Lett 2010; 198:112-8. [PMID: 20553828 DOI: 10.1016/j.toxlet.2010.05.013] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2010] [Revised: 05/18/2010] [Accepted: 05/19/2010] [Indexed: 11/19/2022]
Abstract
High doses of mequindox (MEQ) are associated with oxidative stress and pathological toxicity in the kidney. In this study, we demonstrated long term effects of MEQ on intra- or extra-adrenal renin-angiotensin-aldosterone system (RAAS) in vivo. RAAS plays a major role in aldosterone secretion. High doses of MEQ in the diet for 180 days in male rats led to inhibition of intra- and extra-adrenal RAAS, concident with down-regulation of Na(+)/K(+)-ATPase (NAKA) and mineralocorticoid receptor (MR), the downstream of aldosterone action. Significant changes of malondialdehyde (MDA), reduced glutathione (GSH), and superoxide dismutase (SOD) in kidney were also observed in the high doses (110, 275mg/kg) groups. The mRNA levels of most subunits of NADPH oxidase were significantly upregulated at low doses (25-110mg/kg) but the upregulation was diminished at higher doses in both kidney and adrenal gland, indicating a complicated and contradictory effect of MEQ on NADPH. These results highlight the complex interactions of drug metabolism, RAAS, NADPH oxidase and oxidative stress in response to MEQ-induced tissue toxicity and aldosterone secretion.
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Affiliation(s)
- Xian-Ju Huang
- MOA Key Laboratory of Food Safety Evaluation/National Reference Laboratory of Veterinary Drug Residues (HZAU), Huazhong Agricultural University, Lion Street 1#, Wuhan, Hubei 430070, China.
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Fan LQ, Hardy DO, Catterall JF, Zhao J, Li SX. Identification and characterization of an androgen-responsive Kap promoter enhancer located in the intron II region of human angiotensinogen gene. J Steroid Biochem Mol Biol 2010; 119:135-40. [PMID: 20153828 PMCID: PMC2881338 DOI: 10.1016/j.jsbmb.2010.02.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2008] [Revised: 01/05/2010] [Accepted: 02/04/2010] [Indexed: 11/24/2022]
Abstract
Transgenic expression of the human angiotensinogen (HAGT) gene directed by the mouse kidney androgen-regulated protein (Kap) gene promoter is proximal tubule cell-specific and androgen-regulated in vivo. The same Kap promoter fragment did not support similar regulation of other genes, but a transgene based on the original chimeric KAP-hAGT construct successfully directed NHE3 to kidney, suggesting that sequences within the HAGT gene fragment of the construct contributed to the regulation of its expression in vivo. In the present study, androgen-responsive regulatory sequences in the HAGT gene portions of the transgene were examined in transfected renal cells. A 1.4-kb enhancer between exons 2 and 3 was identified that increased the basal expression of Kap promoter 1.5- to 2-fold, its induction by dihydrotestosterone (DHT) 2- to 3-fold and its induction by dexamethasone (Dex) 4- to 5-fold. Sequence analysis revealed two potential hormone-responsive elements. Mutational assays and electrophoretic mobility shift assay showed one of these elements was androgen-specific. These findings may influence future strategies for the design of inducible, cell-specific transgenes.
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Affiliation(s)
- Li-qiang Fan
- The State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, P. R. China
- Centre for Biomedical Research, Population Council, New York 10021 U.S.A
- Corresponding authors: Li-qiang Fan, Ph.D. PO Box 365, The State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, P. R China. 200237; Tel: 86-21-64252257; Fax: 86-21-64252257; ; Dianne O Hardy, Ph.D. Centre for Biomedical Research, Population Council, 1230 York Avenue, New York, NY 10021 USA; Tel: 1-212-327-8754; Fax: 1-212-327-7678;
| | - Dianne O. Hardy
- Centre for Biomedical Research, Population Council, New York 10021 U.S.A
- Corresponding authors: Li-qiang Fan, Ph.D. PO Box 365, The State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, P. R China. 200237; Tel: 86-21-64252257; Fax: 86-21-64252257; ; Dianne O Hardy, Ph.D. Centre for Biomedical Research, Population Council, 1230 York Avenue, New York, NY 10021 USA; Tel: 1-212-327-8754; Fax: 1-212-327-7678;
| | - James F Catterall
- Centre for Biomedical Research, Population Council, New York 10021 U.S.A
| | - Jian Zhao
- The State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, P. R. China
| | - Su-xia Li
- The State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, P. R. China
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Liu X, Zhao Y, Wang L, Yang X, Zheng Z, Zhang Y, Chen F, Liu H. Overexpression of cytochrome P450 4F2 in mice increases 20-hydroxyeicosatetraenoic acid production and arterial blood pressure. Kidney Int 2009; 75:1288-1296. [PMID: 19279555 DOI: 10.1038/ki.2009.67] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Cytochrome P450 4F2 (CYP4F2) activity is thought to be a factor in the pathogenesis of hypertension through its bioactive metabolite 20-hydroxyeicosatetraenoic acid (20-HETE). We previously found that a gain-in-function CYP4F2 variant in a Chinese cohort was associated with elevated urinary 20-HETE and hypertension. To further explore this association we generated a transgenic mouse model expressing CYP4F2 driven by a modified mouse kidney androgen-regulated protein promoter. This heterologous promoter regulated the expression of luciferase and his-tagged CYP4F2 in transfected HEK 293 cells. In the kidney of transgenic mice, CYP4F2 was localized to renal proximal tubule epithelia and was expressed at a higher level than in control mice, leading to increased urinary 20-HETE excretion. Assessment of CYP4F2 activity by an arachidonic acid hydroxylation assay showed that 20-HETE production was significantly higher in kidney microsomes of transgenic mice compared to control mice, as was their systolic blood pressure. There was a positive correlation of blood pressure with urinary 20-HETE levels. Our results show that increased expression of CYP4F2 in mice enhanced 20-HETE production and elevated blood pressure.
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Affiliation(s)
- Xiaoliang Liu
- Department of Medical Genetics, China Medical University, Shenyang, Liaoning, China
| | - Yanyan Zhao
- Department of Medical Genetics, China Medical University, Shenyang, Liaoning, China.
| | - Luzeng Wang
- Department of Laboratory Animal Center, China Medical University, Shenyang, Liaoning, China
| | - Xianghong Yang
- Department of Pathology, the Second Affiliated Hospital, China Medical University, Shenyang, Liaoning, China
| | - Zhihong Zheng
- Department of Laboratory Animal Center, China Medical University, Shenyang, Liaoning, China
| | - Yuanyuan Zhang
- Department of Medical Genetics, China Medical University, Shenyang, Liaoning, China
| | - Fangjie Chen
- Department of Medical Genetics, China Medical University, Shenyang, Liaoning, China
| | - Hong Liu
- Department of Medical Genetics, China Medical University, Shenyang, Liaoning, China
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Nistala R, Wei Y, Sowers JR, Whaley-Connell A. Renin-angiotensin-aldosterone system-mediated redox effects in chronic kidney disease. Transl Res 2009; 153:102-13. [PMID: 19218092 PMCID: PMC2680726 DOI: 10.1016/j.trsl.2008.12.008] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2008] [Accepted: 12/24/2008] [Indexed: 12/24/2022]
Abstract
The renin-angiotensin-aldosterone system (RAAS) is central to the pathogenesis of hypertension, cardiovascular disease, and kidney disease. Evidence supports various pathways through which a local renal RAAS can affect kidney function, hypertension, and cardiovascular disease. A prominent mechanism seems to be the loss of reduction-oxidation (redox) homeostasis and the formation of excessive free radicals. Free radicals such as reactive oxygen species (ROS) are necessary in normal physiologic processes, which include the development of nephrons, erythropoeisis, and tubular sodium transport. However, the loss of redox homeostasis contributes to proinflammatory and profibrotic pathways in the kidney that in turn lead to decreased vascular compliance, podocyte pathology, and proteinuria. Both the blockade of the RAAS and the oxidative stress produce salutary effects on hypertension and glomerular filtration barrier injury. Thus, the focus of current research is on understanding the pathophysiology of chronic kidney disease in the context of an increased RAAS and unbalanced redox mechanisms.
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Affiliation(s)
- Ravi Nistala
- Department of Internal Medicine, University of Missouri-Columbia School of Medicine, Columbia, MO 65212, USA.
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45
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Rubera I, Hummler E, Beermann F. Transgenic mice and their impact on kidney research. Pflugers Arch 2008; 458:211-22. [PMID: 19084992 DOI: 10.1007/s00424-008-0624-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2008] [Accepted: 11/25/2008] [Indexed: 12/12/2022]
Abstract
The kidney is a key organ in the maintenance of ion and fluid homeostasis and specific transport systems localized along the nephron guarantee this function. Due to its large functional heterogeneity, experiments on the whole organ level cannot be easily performed, and thus more refined tools are needed, like for example the development of specific recombination systems to gain knowledge on the physiological role of single proteins implicated in ion transport. This review introduces the transgenic technology developed over the past decades, and then focuses on recent strategies for generating kidney-specific gene targeting, over-expression, and gene ablation in mice, that will help to understand the physiological role of proteins implicated in salt and water balance in the kidney.
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Kobori H, Alper AB, Shenava R, Katsurada A, Saito T, Ohashi N, Urushihara M, Miyata K, Satou R, Hamm LL, Navar LG. Urinary angiotensinogen as a novel biomarker of the intrarenal renin-angiotensin system status in hypertensive patients. Hypertension 2008; 53:344-50. [PMID: 19075095 DOI: 10.1161/hypertensionaha.108.123802] [Citation(s) in RCA: 158] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
We reported previously that urinary angiotensinogen (UAGT) levels provide a specific index of the intrarenal renin-angiotensin system (RAS) status in angiotensin II-dependent hypertensive rats. To study this system in humans, we recently developed a human angiotensinogen ELISA. To test the hypothesis that UAGT is increased in hypertensive patients, we recruited 110 adults. Four subjects with estimated glomerular filtration levels <30 mL/min per 1.73 m(2) were excluded because previous studies have already shown that UAGT is highly correlated with estimated glomerular filtration in this stage of chronic kidney disease. Consequently, 106 paired samples of urine and plasma were analyzed from 70 hypertensive patients (39 treated with RAS blockers [angiotensin-converting enzyme inhibitors or angiotensin II type 1 receptor blockers; systolic blood pressure: 139+/-3 mm Hg] and 31 not treated with RAS blockers [systolic blood pressure: 151+/-4 mm Hg]) and 36 normotensive subjects (systolic blood pressure: 122+/-2 mm Hg). UAGT, normalized by urinary concentrations of creatinine, were not correlated with race, gender, age, height, body weight, body mass index, fractional excretion of sodium, plasma angiotensinogen levels, or estimated glomerular filtration. However, UAGT/urinary concentration of creatinine was significantly positively correlated with systolic blood pressure, diastolic blood pressure, urinary albumin:creatinine ratio (r=0.5994), and urinary protein:creatinine ratio (r=0.4597). UAGT/urinary concentration of creatinine was significantly greater in hypertensive patients not treated with RAS blockers (25.00+/-4.96 microg/g) compared with normotensive subjects (13.70+/-2.33 microg/g). Importantly, patients treated with RAS blockers exhibited a marked attenuation of this augmentation (13.26+/-2.60 microg/g). These data indicate that UAGT is increased in hypertensive patients, and treatment with RAS blockers suppresses UAGT, suggesting that the efficacy of RAS blockade to reduce the intrarenal RAS activity can be assessed by measurements of UAGT.
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Affiliation(s)
- Hiroyuki Kobori
- Department of Medicine, Renal Center of Excellence, Tulane University Health Sciences Center, 1430 Tulane Ave, New Orleans, LA 70112-2699, USA.
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Abstract
Loss of redox homeostasis and formation of excessive free radicals play an important role in the pathogenesis of kidney disease and hypertension. Free radicals such as reactive oxygen species (ROS) are necessary in physiologic processes. However, loss of redox homeostasis contributes to proinflammatory and profibrotic pathways in the kidney, which in turn lead to reduced vascular compliance and proteinuria. The kidney is susceptible to the influence of various extracellular and intracellular cues, including the renin-angiotensin-aldosterone system (RAAS), hyperglycemia, lipid peroxidation, inflammatory cytokines, and growth factors. Redox control of kidney function is a dynamic process with reversible pro- and anti-free radical processes. The imbalance of redox homeostasis within the kidney is integral in hypertension and the progression of kidney disease. An emerging paradigm exists for renal redox contribution to hypertension.
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Affiliation(s)
- Ravi Nistala
- University of Missouri-Columbia School of Medicine, Department of Internal Medicine, Columbia, Missouri 65212, USA.
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Fan L, Hardy DO, Catteral JF, Zhao J, Li S. Identification and characterization of the minimal androgen-regulated kidney-specific kidney androgen-regulated protein gene promoter. Acta Biochim Biophys Sin (Shanghai) 2008; 40:979-88. [PMID: 19089304 DOI: 10.1111/j.1745-7270.2008.00482.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
The kidney androgen-regulated protein (Kap) gene is tissue specific and regulated by androgen in mouse kidney proximal tubule cells (PTCs). In the present study, we aimed to identify the minimal PTC-specific androgen-regulated Kap promoter and analyze its androgen response elements (AREs). A deletion series of the Kap1542 promoter/luciferase constructs were assayed in opossum kidney (OK) PTCs in the presence or absence of 15 nM dihydrotestosterone (DHT). Kap1542 and Kap637 had low activity and no androgen induction; Kap224 had a basal activity that was 4- to 5-fold higher than that of Kap1542, but was only slightly induced by DHT. Kap147 had a basal activity that was 2- to 3-fold higher than that of Kap1542 and was induced by DHT 4- to 6-fold. Kap77 abolished basal promoter activity but was still induced by DHT. Results showed that, in vitro, Kap147 was a minimal androgen-regulated promoter. Transient transfection in different cells demonstrated that Kap147 specifically initiated reporter gene expression in PTCs. Sequence analysis revealed two potential AREs located at positions -124 and -39 of Kap147. Mutational assays showed that only the ARE at -124 was involved in androgen response in OK cells. Electrophoretic mobility shift assay also verified -124 ARE bound specifically to androgen receptor. In conclusion, we defined the minimal Kap147 promoter that may be a good model for the study of kidney PTC-specific expression and molecular mechanisms that lead to an androgen-specific responsiveness in vivo.
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Affiliation(s)
- Liqiang Fan
- The State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China.
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49
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Kohan DE. Progress in gene targeting: using mutant mice to study renal function and disease. Kidney Int 2008; 74:427-37. [PMID: 18418351 DOI: 10.1038/ki.2008.146] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Genetic engineering in mice has provided much information about gene function in renal health and disease. This knowledge has largely come from conventional transgenic approaches. Recently, methods have been developed to control the cell type, timing and reversibility of target gene expression. Advances in identifying promoters conferring renal cell-specific gene regulation in vivo have greatly facilitated interpretation of gene targeting studies. Site-specific recombinases have permitted cell-specific knockout of genes; Cre is the preeminent recombinase, but recent progress with other recombinases, include Flp and PhiC31, will likely increase the usefulness of this class of enzymes. Temporally regulated gene expression, particularly using doxycycline- and tamoxifen-inducible systems, holds great promise for avoiding developmental effects of gene mutations as well as facilitating comparison of the same animal's phenotype before and after gene modification. RNA interference is undergoing tremendous growth and has great potential for achieving gene knockdown quickly and reversibly. To date, however, the utility of these systems in modifying renal function in transgenic mice remains unproven. Finally, new gene targeting tools are in development that may substantially simplify generation of transgenic animals. This review discusses the state-of-the-art in gene targeting in the kidney, reviewing function, indications and limitations of the molecular biologic tools.
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Affiliation(s)
- Donald E Kohan
- Division of Nephrology, Department of Internal Medicine, University of Utah Health Sciences Center, Salt Lake City, Utah 84132, USA.
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50
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Li H, Zhou X, Davis DR, Xu D, Sigmund CD. An androgen-inducible proximal tubule-specific Cre recombinase transgenic model. Am J Physiol Renal Physiol 2008; 294:F1481-6. [PMID: 18385272 DOI: 10.1152/ajprenal.00064.2008] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
To facilitate the study of renal proximal tubules, we generated a transgenic mouse strain expressing an improved Cre recombinase (iCre) under the control of the kidney androgen-regulated protein (KAP) promoter. The transgene was expressed in the kidney of male mice but not in female mice. Treatment of female transgenic mice with androgen induced robust expression of the transgene in the kidney. We confirmed the presence of Cre recombinase activity and the cell specificity by breeding the KAP2-iCRE mice with ROSA26 reporter mice. X-Gal staining of kidney sections from male double transgenic mice showed robust staining in the epithelial cells of renal proximal tubules. beta-Gal staining in female mice became evident in proximal tubules after administration of androgen. This model of inducible Cre recombinase in the renal proximal tubule should provide a novel useful tool for studying the physiological significance of genes expressed in the renal proximal tubule. This has advantages over other current models where Cre recombinase expression is constitutive, not inducible.
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Affiliation(s)
- Huiping Li
- Dept. of Internal Medicine, 3181B Medical Education and Biomedical Research Facility, Roy J. and Lucille A. Carver College of Medicine, Univ. of Iowa, Iowa City, IA 52242, USA
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