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Samarakoon R, Overstreet JM, Higgins PJ. TGF-β signaling in tissue fibrosis: redox controls, target genes and therapeutic opportunities. Cell Signal 2012; 25:264-8. [PMID: 23063463 DOI: 10.1016/j.cellsig.2012.10.003] [Citation(s) in RCA: 269] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2012] [Accepted: 10/07/2012] [Indexed: 10/27/2022]
Abstract
During development of TGF-β1-initiated fibroproliferative disorders, NADPH oxidases (NOX family members) generate reactive oxygen species (ROS) resulting in downstream transcription of a subset genes encoding matrix structural elements and profibrotic factors. Prominent among the repertoire of disease-implicated genes is the TGF-β1 target gene encoding the potent profibrotic matricellular protein plasminogen activator inhibitor-1 (PAI-1 or SERPINE1). PAI-1 is the major physiologic inhibitor of the plasmin-based pericellular cascade and a causative factor in the development of vascular thrombotic and fibroproliferative disorders. ROS generation in response to TGF-β1 stimulation is rapid and precedes PAI-1 induction; engagement of non-SMAD (e.g., EGFR, Src kinase, MAP kinases, p53) and SMAD2/3 pathways are both required for PAI-1 expression and are ROS-dependent. Recent findings suggest a novel role for p53 in TGF-β1-induced PAI-1 transcription that involves ROS generation and p53/SMAD interactions. Targeting ROS and ROS-activated cellular events is likely to have therapeutic implications in the management of fibrotic disorders, particularly in the context of prolonged TGF-β1 signaling.
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Affiliation(s)
- Rohan Samarakoon
- Center for Cell Biology and Cancer Research, Albany Medical College, 47 New Scotland Avenue, Albany, NY 12208, USA
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52
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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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Chang SY, Chen YW, Zhao XP, Chenier I, Tran S, Sauvé A, Ingelfinger JR, Zhang SL. Catalase prevents maternal diabetes-induced perinatal programming via the Nrf2-HO-1 defense system. Diabetes 2012; 61:2565-74. [PMID: 22733796 PMCID: PMC3447903 DOI: 10.2337/db12-0248] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
We investigated whether overexpression of catalase (CAT) in renal proximal tubular cells (RPTCs) could prevent the programming of hypertension and kidney disease in the offspring of dams with maternal diabetes. Male offspring of nondiabetic and diabetic dams from two transgenic (Tg) lines (Hoxb7-green fluorescent protein [GFP]-Tg [controls] and Hoxb7/CAT-GFP-Tg, which overexpress CAT in RPTCs) were studied from the prenatal period into adulthood. Nephrogenesis, systolic blood pressure, renal hyperfiltration, kidney injury, and reactive oxygen species (ROS) generation were assessed. Gene expression of transforming growth factor-β1 (TGF-β1), nuclear factor erythroid 2p45-related factor-2 (Nrf2), and heme oxygenase-1 (HO-1) was tested in both in vitro and in vivo studies. Renal dysmorphogenesis was observed in offspring of Hoxb7-GFP-Tg dams with severe maternal diabetes; the affected male offspring displayed higher renal ROS generation and developed hypertension and renal hyperfiltration as well as renal injury with heightened TGF-β1 expression in adulthood. These changes were ameliorated in male offspring of diabetic Hoxb7/CAT-GFP-Tg dams via the Nrf2-HO-1 defense system. CAT promoted Nrf2 nuclear translocation and HO-1 gene expression, seen in both in vitro and in vivo studies. In conclusion, CAT overexpression in the RPTCs ameliorated maternal diabetes-induced perinatal programming, mediated, at least in part, by triggering the Nrf2-HO-1 defense system.
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Affiliation(s)
- Shiao-Ying Chang
- Centre de Recherche du Centre Hospitalier de l’Université de Montréal (CRCHUM), Hôpital Hôtel-Dieu, Université de Montréal, Montréal, Québec, Canada
| | - Yun-Wen Chen
- Centre de Recherche du Centre Hospitalier de l’Université de Montréal (CRCHUM), Hôpital Hôtel-Dieu, Université de Montréal, Montréal, Québec, Canada
| | - Xin-Ping Zhao
- Centre de Recherche du Centre Hospitalier de l’Université de Montréal (CRCHUM), Hôpital Hôtel-Dieu, Université de Montréal, Montréal, Québec, Canada
| | - Isabelle Chenier
- Centre de Recherche du Centre Hospitalier de l’Université de Montréal (CRCHUM), Hôpital Hôtel-Dieu, Université de Montréal, Montréal, Québec, Canada
| | - Stella Tran
- Centre de Recherche du Centre Hospitalier de l’Université de Montréal (CRCHUM), Hôpital Hôtel-Dieu, Université de Montréal, Montréal, Québec, Canada
| | - Alexandre Sauvé
- Centre de Recherche du Centre Hospitalier de l’Université de Montréal (CRCHUM), Hôpital Hôtel-Dieu, Université de Montréal, Montréal, Québec, Canada
| | - Julie R. Ingelfinger
- Pediatric Nephrology Unit, Massachusetts General Hospital, and Harvard Medical School, Boston, Massachusetts
| | - Shao-Ling Zhang
- Centre de Recherche du Centre Hospitalier de l’Université de Montréal (CRCHUM), Hôpital Hôtel-Dieu, Université de Montréal, Montréal, Québec, Canada
- Corresponding author: Shao-Ling Zhang,
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Christensen EI, Birn H, Storm T, Weyer K, Nielsen R. Endocytic Receptors in the Renal Proximal Tubule. Physiology (Bethesda) 2012; 27:223-36. [DOI: 10.1152/physiol.00022.2012] [Citation(s) in RCA: 170] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Protein reabsorption is a predominant feature of the renal proximal tubule. Animal studies show that the ability to rescue plasma proteins relies on the endocytic receptors megalin and cubilin. Recently, studies of patients with syndromes caused by dysfunctional receptors have supported the importance of these for protein clearance of human ultrafiltrate. This review focuses on the molecular biology and physiology of the receptors and their involvement in renal pathological conditions.
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Affiliation(s)
- Erik I. Christensen
- Department of Biomedicine, Faculty of Health Sciences, Aarhus University, Aarhus, Denmark
| | - Henrik Birn
- Department of Biomedicine, Faculty of Health Sciences, Aarhus University, Aarhus, Denmark
| | - Tina Storm
- Department of Biomedicine, Faculty of Health Sciences, Aarhus University, Aarhus, Denmark
| | - Kathrin Weyer
- Department of Biomedicine, Faculty of Health Sciences, Aarhus University, Aarhus, Denmark
| | - Rikke Nielsen
- Department of Biomedicine, Faculty of Health Sciences, Aarhus University, Aarhus, Denmark
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Ojeda NB, Hennington BS, Williamson DT, Hill ML, Betson NE, Sartori-Valinotti JC, Reckelhoff JF, Royals TP, Alexander BT. Oxidative stress contributes to sex differences in blood pressure in adult growth-restricted offspring. Hypertension 2012; 60:114-22. [PMID: 22585945 PMCID: PMC3655434 DOI: 10.1161/hypertensionaha.112.192955] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2012] [Accepted: 04/20/2012] [Indexed: 02/07/2023]
Abstract
Numerous experimental studies suggest that oxidative stress contributes to the pathophysiology of hypertension and, importantly, that oxidative stress plays a more definitive role in mediating hypertension in males than in females. Intrauterine growth restriction induced by reduced uterine perfusion initiated at day 14 of gestation in the rat programs hypertension in adult male growth-restricted offspring; yet, female growth-restricted offspring are normotensive. The mechanisms mediating sex differences in blood pressure in adult growth-restricted offspring are not clear. Thus, this study tested the hypothesis that sex-specific differences in renal oxidative stress contribute to the regulation of blood pressure in adult growth-restricted offspring. A significant increase in blood pressure measured by telemetry in male growth-restricted offspring (P<0.05) was associated with a marked increase in renal markers of oxidative stress (P<0.05). Chronic treatment with the antioxidant Tempol had no effect on blood pressure in male control offspring, but it normalized blood pressure (P<0.05) and renal markers of oxidative stress (P<0.05) in male growth-restricted offspring relative to male control offspring. Renal markers of oxidative stress were not elevated in female growth-restricted offspring; however, renal activity of the antioxidant catalase was significantly elevated relative to female control offspring (P<0.05). Chronic treatment with Tempol did not significantly alter oxidative stress or blood pressure measured by telemetry in female offspring. Thus, these data suggest that sex differences in renal oxidative stress and antioxidant activity are present in adult growth-restricted offspring and that oxidative stress may play a more important role in modulating blood pressure in male but not female growth-restricted offspring.
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Affiliation(s)
- Norma B. Ojeda
- Department of Pediatrics, University of Mississippi Medical Center, Jackson, MS
- Department of Physiology, University of Mississippi Medical Center, Jackson, MS
- Department of Physiology and the Women’s Health Research Center, University of Mississippi Medical Center, Jackson, MS
| | - Bettye Sue Hennington
- Department of Physiology and the Women’s Health Research Center, University of Mississippi Medical Center, Jackson, MS
- Department of Biology, Tougaloo College, Tougaloo, MS
| | | | | | | | | | - Jane F. Reckelhoff
- Department of Physiology, University of Mississippi Medical Center, Jackson, MS
- Department of Physiology and the Women’s Health Research Center, University of Mississippi Medical Center, Jackson, MS
| | - Thomas P. Royals
- Department of Physiology, University of Mississippi Medical Center, Jackson, MS
| | - Barbara T. Alexander
- Department of Physiology, University of Mississippi Medical Center, Jackson, MS
- Department of Physiology and the Women’s Health Research Center, University of Mississippi Medical Center, Jackson, MS
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56
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Montezano AC, Touyz RM. Oxidative stress, Noxs, and hypertension: experimental evidence and clinical controversies. Ann Med 2012; 44 Suppl 1:S2-16. [PMID: 22713144 DOI: 10.3109/07853890.2011.653393] [Citation(s) in RCA: 133] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Reactive oxygen species (ROS) are signaling molecules that influence many physiological processes. Increased ROS bioavailability and altered redox signaling (oxidative stress) have been implicated in chronic diseases including hypertension. Although oxidative stress may not be the sole cause of hypertension, it amplifies blood pressure elevation in the presence of other prohypertensive factors (salt, renin-angiotensin system, sympathetic hyperactivity). A major source for cardiovascular ROS is a family of non-phagocytic NADPH oxidases (Nox1, Nox2, Nox4, Nox5). Other sources of ROS involve mitochondrial electron transport enzymes, xanthine oxidase, and uncoupled nitric oxide synthase. Although evidence from experimental and animal studies supports a role for oxidative stress in the pathogenesis of hypertension, there is still no convincing proof that oxidative stress is a cause of human hypertension. However, what is clear is that oxidative stress is important in the molecular mechanisms associated with cardiovascular and renal injury in hypertension and that hypertension itself can contribute to oxidative stress. The present review addresses the putative function of ROS in the pathogenesis of hypertension and focuses on the role of Noxs in ROS generation in vessels and the kidney. Implications of oxidative stress in human hypertension are discussed, and clinical uncertainties are highlighted.
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Affiliation(s)
- Augusto C Montezano
- Kidney Research Centre, Ottawa Hospital Research Institute, University of Ottawa, Ottawa, Ontario, Canada
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57
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Takiue K, Sugiyama H, Inoue T, Morinaga H, Kikumoto Y, Kitagawa M, Kitamura S, Maeshima Y, Wang DH, Masuoka N, Ogino K, Makino H. Acatalasemic mice are mildly susceptible to adriamycin nephropathy and exhibit increased albuminuria and glomerulosclerosis. BMC Nephrol 2012; 13:14. [PMID: 22443450 PMCID: PMC3329410 DOI: 10.1186/1471-2369-13-14] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2011] [Accepted: 03/25/2012] [Indexed: 11/30/2022] Open
Abstract
Background Catalase is an important antioxidant enzyme that regulates the level of intracellular hydrogen peroxide and hydroxyl radicals. The effects of catalase deficiency on albuminuria and progressive glomerulosclerosis have not yet been fully elucidated. The adriamycin (ADR) nephropathy model is considered to be an experimental model of focal segmental glomerulosclerosis. A functional catalase deficiency was hypothesized to exacerbate albuminuria and the progression of glomerulosclerosis in this model. Methods ADR was intravenously administered to both homozygous acatalasemic mutant mice (C3H/AnLCsbCsb) and control wild-type mice (C3H/AnLCsaCsa). The functional and morphological alterations of the kidneys, including albuminuria, renal function, podocytic, glomerular and tubulointerstitial injuries, and the activities of catalase were then compared between the two groups up to 8 weeks after disease induction. Moreover, the presence of a mutation of the toll-like receptor 4 (tlr4) gene, which was previously reported in the C3H/HeJ strain, was investigated in both groups. Results The ADR-treated mice developed significant albuminuria and glomerulosclerosis, and the degree of these conditions in the ADR-treated acatalasemic mice was higher than that in the wild-type mice. ADR induced progressive renal fibrosis, renal atrophy and lipid peroxide accumulation only in the acatalasemic mice. In addition, the level of catalase activity was significantly lower in the kidneys of the acatalasemic mice than in the wild-type mice during the experimental period. The catalase activity increased after ADR injection in wild-type mice, but the acatalasemic mice did not have the ability to increase their catalase activity under oxidative stress. The C3H/AnL strain was found to be negative for the tlr4 gene mutation. Conclusions These data indicate that catalase deficiency plays an important role in the progression of renal injury in the ADR nephropathy model.
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Affiliation(s)
- Keiichi Takiue
- Department of Medicine and Clinical Science, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1 Shikatacho, Kita-ku, Okayama 700-8558, Japan
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58
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Dołęgowska B, Błogowski W, Domański L. Association between the perioperative antioxidative ability of platelets and early post-transplant function of kidney allografts: a pilot study. PLoS One 2012; 7:e29779. [PMID: 22279544 PMCID: PMC3261166 DOI: 10.1371/journal.pone.0029779] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2011] [Accepted: 12/04/2011] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Recent studies have demonstrated that the actions of platelets may unfavorably influence post-transplant function of organ allografts. In this study, the association between post-transplant graft function and the perioperative activity of platelet antioxidants was examined among kidney recipients divided into early (EGF), slow (SGF), and delayed graft function (DGF) groups. METHODOLOGY/PRINCIPAL FINDINGS Activities of superoxide dismutase, catalase, glutathione transferase (GST), glutathione peroxidase, and glucose-6-phosphate dehydrogenase (G6P) were determined and levels of glutathione, oxidized glutathione, and isoprostane were measured in blood samples collected immediately before and during the first and fifth minutes of renal allograft reperfusion. Our results demonstrated a significant increase in isoprostane levels in all groups. Interestingly, in DGF patients, significantly lower levels of perioperative activity of catalase (p<0.02) and GST (p<0.02) were observed. Moreover, in our study, the activity of platelet antioxidants was associated with intensity of perioperative oxidative stress. For discriminating SGF/DGF from EGF, sensitivity, specificity, and positive and negative predictive values of platelet antioxidants were 81-91%, 50-58%, 32-37%, and 90-90.5%, respectively. CONCLUSIONS During renal transplantation, significant changes occur in the activity of platelet antioxidants. These changes seem to be associated with post-transplant graft function and can be potentially used to differentiate between EGF and SGF/DGF. To the best of our knowledge, this is the first study to reveal the potential protective role of platelets in the human transplantation setting.
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Affiliation(s)
- Barbara Dołęgowska
- Department of Laboratory Diagnostics and Molecular Medicine, Pomeranian Medical University, Szczecin, Poland
| | - Wojciech Błogowski
- Department of Laboratory Diagnostics and Molecular Medicine, Pomeranian Medical University, Szczecin, Poland
- * E-mail:
| | - Leszek Domański
- Department of Nephrology, Transplantation and Internal Medicine, Pomeranian Medical University, Szczecin, Poland
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Hamilton RT, Walsh ME, Van Remmen H. Mouse Models of Oxidative Stress Indicate a Role for Modulating Healthy Aging. ACTA ACUST UNITED AC 2012; Suppl 4. [PMID: 25300955 DOI: 10.4172/2161-0681.s4-005] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Aging is a complex process that affects every major system at the molecular, cellular and organ levels. Although the exact cause of aging is unknown, there is significant evidence that oxidative stress plays a major role in the aging process. The basis of the oxidative stress hypothesis is that aging occurs as a result of an imbalance between oxidants and antioxidants, which leads to the accrual of damaged proteins, lipids and DNA macromolecules with age. Age-dependent increases in protein oxidation and aggregates, lipofuscin, and DNA mutations contribute to age-related pathologies. Many transgenic/knockout mouse models over expressing or deficient in key antioxidant enzymes have been generated to examine the effect of oxidative stress on aging and age-related diseases. Based on currently reported lifespan studies using mice with altered antioxidant defense, there is little evidence that oxidative stress plays a role in determining lifespan. However, mice deficient in antioxidant enzymes are often more susceptible to age-related disease while mice overexpressing antioxidant enzymes often have an increase in the amount of time spent without disease, i.e., healthspan. Thus, by understanding the mechanisms that affect healthy aging, we may discover potential therapeutic targets to extend human healthspan.
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Affiliation(s)
- Ryan T Hamilton
- Barshop Institute for Longevity and Aging Studies, University of Texas Health Science Center at San Antonio, 15355 Lambda Drive, San Antonio, TX 78245-3207, USA ; Department of Cellular and Structural Biology, University of Texas Health Science Center at San Antonio, 15355 Lambda Drive, San Antonio, TX 78245-3207, USA
| | - Michael E Walsh
- Department of Cellular and Structural Biology, University of Texas Health Science Center at San Antonio, 15355 Lambda Drive, San Antonio, TX 78245-3207, USA
| | - Holly Van Remmen
- Barshop Institute for Longevity and Aging Studies, University of Texas Health Science Center at San Antonio, 15355 Lambda Drive, San Antonio, TX 78245-3207, USA ; Department of Cellular and Structural Biology, University of Texas Health Science Center at San Antonio, 15355 Lambda Drive, San Antonio, TX 78245-3207, USA ; GRECC, South Texas Veterans Health Care System, San Antonio, TX, USA
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60
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Lo CS, Liu F, Shi Y, Maachi H, Chenier I, Godin N, Filep JG, Ingelfinger JR, Zhang SL, Chan JSD. Dual RAS blockade normalizes angiotensin-converting enzyme-2 expression and prevents hypertension and tubular apoptosis in Akita angiotensinogen-transgenic mice. Am J Physiol Renal Physiol 2011; 302:F840-52. [PMID: 22205225 DOI: 10.1152/ajprenal.00340.2011] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
We investigated the effects of dual renin-angiotensin system (RAS) blockade on angiotensin-converting enzyme-2 (Ace2) expression, hypertension, and renal proximal tubular cell (RPTC) apoptosis in type 1 diabetic Akita angiotensinogen (Agt)-transgenic (Tg) mice that specifically overexpress Agt in their RPTCs. Adult (11 wk old) male Akita and Akita Agt-Tg mice were treated with two RAS blockers (ANG II receptor type 1 blocker losartan, 30 mg·kg(-1)·day(-1)) and angiotensin-converting enzyme (ACE) inhibitor perindopril (4 mg·kg(-1)·day(-1)) in drinking water. Same-age non-Akita littermates and Agt-Tg mice served as controls. Blood pressure, blood glucose, and albuminuria were monitored weekly. The animals were euthanized at age 16 wk. The left kidneys were processed for immunohistochemistry and apoptosis studies. Renal proximal tubules were isolated from the right kidneys to assess gene and protein expression. Urinary ANG II and ANG 1-7 were quantified by ELISA. RAS blockade normalized renal Ace2 expression and urinary ANG 1-7 levels (both of which were low in untreated Akita and Akita Agt-Tg), prevented hypertension, albuminuria, tubulointerstitial fibrosis and tubular apoptosis, and inhibited profibrotic and proapoptotic gene expression in RPTCs of Akita and Akita Agt-Tg mice compared with non-Akita controls. Our results demonstrate the effectiveness of RAS blockade in preventing intrarenal RAS activation, hypertension, and nephropathy progression in diabetes and support the important role of intrarenal Ace2 expression in modulating hypertension and renal injury in diabetes.
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Affiliation(s)
- Chao-Sheng Lo
- Université de Montréal, Centre de Recherche, Centre Hospitalier de l'Université de Montréal, Hôtel-Dieu Hospital, Pavillon Masson, 3850 St. Urbain St., Montreal, Quebec, Canada
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61
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Development of Angiotensin II-induced Abdominal Aortic Aneurysms Is Independent of Catalase in Mice. J Cardiovasc Pharmacol 2011; 58:633-8. [DOI: 10.1097/fjc.0b013e3182317196] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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62
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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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63
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Angiotensin II type II receptor deficiency accelerates the development of nephropathy in type I diabetes via oxidative stress and ACE2. EXPERIMENTAL DIABETES RESEARCH 2011; 2011:521076. [PMID: 22110472 PMCID: PMC3205615 DOI: 10.1155/2011/521076] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/25/2011] [Revised: 07/11/2011] [Accepted: 07/20/2011] [Indexed: 01/06/2023]
Abstract
Since the functional role(s) of angiotensin II (Ang II) type II receptor (AT2R) in type I diabetes is unknown, we hypothesized that AT2R is involved in decreasing the effects of type I diabetes on the kidneys. We induced diabetes with low-dose streptozotocin (STZ) in both AT2R knockout (AT2RKO) and wild-type (WT) male mice aged 12 weeks and followed them for 4 weeks. Three subgroups nondiabetic, diabetic, and insulin-treated diabetic (Rx insulin implant) were studied. Systolic blood pressure (SBP), physiological parameters, glomerular filtration rate (GFR), renal morphology, gene expression, and apoptosis were assessed. After 4 weeks of diabetes, compared to WT controls, AT2RKO mice clearly developed features of early diabetic nephropathy (DN), such as renal hypertrophy, tubular apoptosis, and progressive extracellular matrix (ECM) protein accumulation as well as increased GFR. AT2RKO mice presented hypertension unaffected by diabetes. Renal oxidative stress (measured as heme oxygenase 1 (HO-1) gene expression and reactive oxygen species (ROS) generation) and intrarenal renin angiotensin system components, such as angiotensinogen (Agt), AT1R, and angiotensin-converting enzyme (ACE) gene expression, were augmented whereas angiotensin-converting enzyme2 (ACE2) gene expression was decreased in renal proximal tubules (RPTs) of AT2RKO mice. The renal changes noted above were significantly enhanced in diabetic AT2RKO mice but partially attenuated in insulin-treated diabetic WT and AT2RKO mice. In conclusion, AT2R deficiency accelerates the development of DN, which appears to be mediated, at least in part, via heightened oxidative stress and ACE/ACE2 ratio in RPTs.
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Downregulation of the antioxidant protein peroxiredoxin 2 contributes to angiotensin II-mediated podocyte apoptosis. Kidney Int 2011; 80:959-969. [PMID: 21814176 PMCID: PMC3257043 DOI: 10.1038/ki.2011.250] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Podocytes have a significant role in establishing selective permeability of the glomerular filtration barrier. Sustained renin–angiotensin–aldosterone system activation is crucial to the pathogenesis of podocyte injury, but the mechanisms by which angiotensin II modulates podocyte survival due to physiological or injurious stimuli remain unclear. Here, we used proteomic analysis to find new mediators of angiotensin II–induced podocyte injury. Antioxidant protein peroxiredoxin 2 expression was decreased in cultured podocytes stimulated with angiotensin II. Peroxiredoxin 2 was found to be expressed in podocytes in vivo, and its expression was decreased in the glomeruli of rats transgenic for angiotensin II type 1 receptors in a podocyte-specific manner, or in rats infused with angiotensin II. Downregulation of peroxiredoxin 2 in podocytes resulted in increased reactive oxygen species release, protein overoxidation, and inhibition of the Akt pathway. Both treatment with angiotensin II and downregulation of peroxiredoxin 2 expression led to apoptosis of podocytes. Thus, peroxiredoxin 2 is an important modulator of angiotensin II–induced podocyte injury.
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65
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The proximal tubular renin–angiotensin system during albuminuria. J Hypertens 2011; 29:1292-4. [DOI: 10.1097/hjh.0b013e328348f031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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66
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Yang W, Zhang J, Wang H, Gao P, Singh M, Shen K, Fang N. Angiotensin II downregulates catalase expression and activity in vascular adventitial fibroblasts through an AT1R/ERK1/2-dependent pathway. Mol Cell Biochem 2011; 358:21-9. [PMID: 21660462 DOI: 10.1007/s11010-011-0915-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2010] [Accepted: 05/28/2011] [Indexed: 02/07/2023]
Abstract
Angiotensin II (Ang II) plays a profound regulatory effect on NADPH oxidase and the functional features of vascular adventitial fibroblasts, but its role in antioxidant enzyme defense remains unclear. This study investigated the effect of Ang II on expressions and activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) in adventitial fibroblasts and the possible mechanism involved. Ang II decreased the expression and activity of CAT in a dose- and time-dependent manner, but not that of SOD and GPx. The effects were abolished by the angiotensin II type 1 receptor (AT1R) blocker losartan and AT1R small-interfering RNA (siRNA). Incubation with polyethylene glycol-CAT prevented the Ang II-induced effects on reactive oxygen species (ROS) generation and myofibroblast differentiation. Moreover, Ang II rapidly induced phosphorylation of ERK1/2, which was reversed by losartan and AT1R siRNA. Pharmacological blockade of ERK1/2 improved Ang II-induced decrease in CAT protein expression. These in vitro results indicate that Ang II induces ERK1/2 activation, contributing to the downregulation of CAT as well as promoting oxidative stress and adventitial fibroblast phenotypic differentiation in an AT1R-mediated manner.
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Affiliation(s)
- Weiwei Yang
- Department of Geriatrics, RenJi Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200001, China
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67
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Navar LG, Kobori H, Prieto MC, Gonzalez-Villalobos RA. Intratubular renin-angiotensin system in hypertension. Hypertension 2011; 57:355-62. [PMID: 21282552 PMCID: PMC3073668 DOI: 10.1161/hypertensionaha.110.163519] [Citation(s) in RCA: 177] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- L Gabriel Navar
- Department of Physiology, SL39, Tulane University Health Science Center, 1430 Tulane Ave, New Orleans, LA 70112, USA.
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68
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Benefits of catalase overexpression in renal proximal tubular cells. Kidney Int 2010; 77:1060-2. [PMID: 20508664 DOI: 10.1038/ki.2010.94] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The intrarenal renin-angiotensin system and reactive oxygen species contribute to the progression of chronic kidney disease. Godin et al. applied transgenic methods to prove renoprotection by catalase. They show that all of the pathological effects of overexpression of angiotensinogen can be attributed to stimulation of hydrogen peroxide pathways. This indicates a protective role for catalase and underscores the importance of the intrarenal renin-angiotensin system in renal disease.
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