101
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Fatty acids are novel nutrient factors to regulate mTORC1 lysosomal localization and apoptosis in podocytes. Biochim Biophys Acta Mol Basis Dis 2014; 1842:1097-108. [DOI: 10.1016/j.bbadis.2014.04.001] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2013] [Revised: 03/03/2014] [Accepted: 04/02/2014] [Indexed: 11/17/2022]
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102
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Abstract
Chronic kidney disease (CKD) is becoming a worldwide epidemic, driven largely by the dramatic rise in the prevalence of diabetes and obesity. Novel targets and treatments for CKD are, therefore, desperately needed-to both mitigate the burden of this disease in the general population and reduce the necessity for renal replacement therapy in individual patients. This Review highlights new insights into the mechanisms that contribute to CKD, and approaches that might facilitate the development of disease-arresting therapies for CKD. Particular focus is given to therapeutic approaches using antifibrotic agents that target the transforming growth factor β superfamily. In addition, we discuss new insights regarding the roles of vascular calcification, the NADPH oxidase family, and inflammation in the pathogenesis of CKD. We also highlight a new understanding regarding kidney energy sensing pathways (AMPK, sirtuins, and mTOR) in a variety of kidney diseases and how they are linked to inflammation and fibrosis. Finally, exciting new insights have been made into the role of mitochondrial function and mitochondrial biogenesis in relation to progressive kidney disease. Prospective therapeutics based on these findings will hopefully renew hope for clinicians and patients in the near future.
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Affiliation(s)
- Anne-Emilie Declèves
- Laboratory of Experimental Nephrology, Faculty of Medicine, Université Libre de Bruxelles (ULB), CP603, 808 Route de Lennik, 1070 Brussels, Belgium
| | - Kumar Sharma
- Center for Renal Translational Medicine, University of California, San Diego and Veterans Affairs San Diego Healthcare System, Stein Clinical Research Building, 4th Floor, 9500 Gilman Drive, La Jolla, CA 92093-0711, USA
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103
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Ubiquitination-dependent CARM1 degradation facilitates Notch1-mediated podocyte apoptosis in diabetic nephropathy. Cell Signal 2014; 26:1774-82. [PMID: 24726896 DOI: 10.1016/j.cellsig.2014.04.008] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Accepted: 04/06/2014] [Indexed: 12/21/2022]
Abstract
Podocyte apoptosis induced by hyperglycemia is considered a critical factor in the development of diabetic nephropathy. Recent studies have implicated Notch signaling in podocyte apoptosis; however, its regulatory mechanisms are not fully understood. In this study, we found that high-glucose treatment increased Notch1 and Jagged-1 expression, the transcriptional activity of Hes, and podocyte apoptosis, and decreased the expression of coactivator-associated arginine methyltransferase 1 (CARM1) in rat podocytes. Transient transfection of CARM1 reversed high-glucose-induced Notch1 expression, the transcriptional activity of Hes, and podocyte apoptosis. Moreover, the silencing of CARM1 using siRNA increased Notch1 expression, the transcriptional activity of Hes, and podocyte apoptosis. However, the Glu(266)-mediated enzymatic activity of CARM1 was not necessary for Notch signaling activation and podocyte apoptosis. Here, we demonstrate that AMP-activated protein kinase alpha (AMPKα) and cannabinoid receptor 1 (CB1R) are regulated by CARM1 and that high-glucose-induced podocyte apoptosis is mediated by a CARM1-AMPKα-Notch1-CB1R signaling axis. We also show that high-glucose-induced CARM1 downregulation is due to ubiquitination-dependent CARM1 degradation. Finally, we demonstrate that CARM1 expression in podocytes was diminished in rats with streptozotocin-induced diabetes compared to vehicle-treated rats. Together, our data provide evidence that ubiquitination-dependent CARM1 degradation in podocytes in diabetes promotes podocyte apoptosis via Notch1 activation. Strategies to preserve CARM1 expression or reduce the enzymatic activity of a ubiquitin ligase specific for CARM1 could be used to prevent podocyte loss in diabetic nephropathy.
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104
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Fiorina P, Vergani A, Bassi R, Niewczas MA, Altintas MM, Pezzolesi MG, D'Addio F, Chin M, Tezza S, Ben Nasr M, Mattinzoli D, Ikehata M, Corradi D, Schumacher V, Buvall L, Yu CC, Chang JM, La Rosa S, Finzi G, Solini A, Vincenti F, Rastaldi MP, Reiser J, Krolewski AS, Mundel PH, Sayegh MH. Role of podocyte B7-1 in diabetic nephropathy. J Am Soc Nephrol 2014; 25:1415-29. [PMID: 24676639 DOI: 10.1681/asn.2013050518] [Citation(s) in RCA: 103] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Podocyte injury and resulting albuminuria are hallmarks of diabetic nephropathy, but targeted therapies to halt or prevent these complications are currently not available. Here, we show that the immune-related molecule B7-1/CD80 is a critical mediator of podocyte injury in type 2 diabetic nephropathy. We report the induction of podocyte B7-1 in kidney biopsy specimens from patients with type 2 diabetes. Genetic and epidemiologic studies revealed the association of two single nucleotide polymorphisms at the B7-1 gene with diabetic nephropathy. Furthermore, increased levels of the soluble isoform of the B7-1 ligand CD28 correlated with the progression to ESRD in individuals with type 2 diabetes. In vitro, high glucose conditions prompted the phosphatidylinositol 3 kinase-dependent upregulation of B7-1 in podocytes, and the ectopic expression of B7-1 in podocytes increased apoptosis and induced disruption of the cytoskeleton that were reversed by the B7-1 inhibitor CTLA4-Ig. Podocyte expression of B7-1 was also induced in vivo in two murine models of diabetic nephropathy, and treatment with CTLA4-Ig prevented increased urinary albumin excretion and improved kidney pathology in these animals. Taken together, these results identify B7-1 inhibition as a potential therapeutic strategy for the prevention or treatment of diabetic nephropathy.
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Affiliation(s)
- Paolo Fiorina
- Nephrology Division, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts; Department of Medicine, San Raffaele Scientific Institute, Milan, Italy;
| | - Andrea Vergani
- Nephrology Division, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts; Department of Medicine, San Raffaele Scientific Institute, Milan, Italy
| | - Roberto Bassi
- Nephrology Division, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts; Department of Medicine, San Raffaele Scientific Institute, Milan, Italy; DiSTeBA, Universita' del Salento, Lecce, Italy
| | - Monika A Niewczas
- Section on Genetics and Epidemiology, Research Division, Joslin Diabetes Center and Department of Medicine, Harvard Medical School, Boston, Massachusetts
| | - Mehmet M Altintas
- Department of Medicine, Rush University Medical Center, Chicago, Illinois
| | - Marcus G Pezzolesi
- Section on Genetics and Epidemiology, Research Division, Joslin Diabetes Center and Department of Medicine, Harvard Medical School, Boston, Massachusetts
| | - Francesca D'Addio
- Nephrology Division, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts; Department of Medicine, San Raffaele Scientific Institute, Milan, Italy
| | - Melissa Chin
- Nephrology Division, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Sara Tezza
- Nephrology Division, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Moufida Ben Nasr
- Nephrology Division, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Deborah Mattinzoli
- Renal Research Laboratory, Fondazione IRCCS Ospedale Maggiore Policlinico and Fondazione D'Amico per la Ricerca sulle Malattie Renali, Milan, Italy
| | - Masami Ikehata
- Renal Research Laboratory, Fondazione IRCCS Ospedale Maggiore Policlinico and Fondazione D'Amico per la Ricerca sulle Malattie Renali, Milan, Italy
| | - Domenico Corradi
- Department of Biomedical, Biotechnological and Translational Sciences, Unit of Pathology, University of Parma, Parma, Italy
| | - Valerie Schumacher
- Nephrology Division, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Lisa Buvall
- Nephrology Division, Massachusetts General Hospital, Boston, Massachusetts
| | - Chih-Chuan Yu
- Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan; Department of Internal Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Jer-Ming Chang
- Department of Internal Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
| | | | - Giovanna Finzi
- Pathology Department, Ospedale di Circolo, Varese, Italy
| | - Anna Solini
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Flavio Vincenti
- Kidney Transplant Service, University of San Francisco, San Francisco, California
| | - Maria Pia Rastaldi
- Renal Research Laboratory, Fondazione IRCCS Ospedale Maggiore Policlinico and Fondazione D'Amico per la Ricerca sulle Malattie Renali, Milan, Italy
| | - Jochen Reiser
- Department of Medicine, Rush University Medical Center, Chicago, Illinois
| | - Andrzej S Krolewski
- Section on Genetics and Epidemiology, Research Division, Joslin Diabetes Center and Department of Medicine, Harvard Medical School, Boston, Massachusetts
| | - Peter H Mundel
- Nephrology Division, Massachusetts General Hospital, Boston, Massachusetts
| | - Mohamed H Sayegh
- Transplantation Research Center, Brigham and Women's Hospital, Boston, Massachusetts; and American University of Beirut, Beirut, Lebanon
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105
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Ha TS, Park HY, Nam JA, Han GD. Diabetic conditions modulate the adenosine monophosphate-activated protein kinase of podocytes. Kidney Res Clin Pract 2014; 33:26-32. [PMID: 26877947 PMCID: PMC4714163 DOI: 10.1016/j.krcp.2014.02.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Revised: 01/10/2014] [Accepted: 02/06/2014] [Indexed: 11/03/2022] Open
Abstract
BACKGROUND Adenosine monophosphate-activated protein kinases (AMPKs), as a sensor of cellular energy status, have been known to play an important role in the pathophysiology of diabetes and its complications. Because AMPKs are known to be expressed in podocytes, it is possible that podocyte AMPKs could be an important contributing factor in the development of diabetic proteinuria. We investigated the roles of AMPKs in the pathological changes in podocytes induced by high-glucose (HG) and advanced glycosylation end products (AGEs) in diabetic proteinuria. METHODS We prepared streptozotocin-induced diabetic renal tissues and cultured rat and mouse podocytes under diabetic conditions with AMPK-modulating agents. The changes in AMPKα were analyzed with confocal imaging and Western blotting under the following conditions: (1) normal glucose (5mM, =control); (2) HG (30mM); (3) AGE-added; or (4) HG plus AGE-added. RESULTS The density of glomerularphospho-AMPKα in experimental diabetic nephropathy decreased as a function of the diabetic duration. Diabetic conditions including HG and AGE changed the localization of phospho-AMPKα from peripheral cytoplasm to internal cytoplasm and peri- and intranuclear areas in podocytes. HG reduced the AMPKα (Thr172) phosphorylation of rat podocytes, and similarly, AGEs reduced the AMPKα (Thr172) phosphorylation of mouse podocytes. The distributional and quantitative changes in phospho-AMPKα caused by diabetic conditions were preventable using AMPK activators, metformin, and 5-aminoimidazole-4-carboxamide-1β-riboside. CONCLUSION We suggest that diabetic conditions induce the relocation and suppression of podocyte AMPKα, which would be a suggestive mechanism in diabetic podocyte injury.
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Affiliation(s)
- Tae-Sun Ha
- Department of Pediatrics, College of Medicine, Chungbuk National University, Cheongju, Korea
| | - Hye-Young Park
- Department of Pediatrics, College of Medicine, Chungbuk National University, Cheongju, Korea
| | - Ja-Ae Nam
- Department of Pediatrics, College of Medicine, Chungbuk National University, Cheongju, Korea
| | - Gi-Dong Han
- Department of Food Science and Technology, College of Natural Resources, Yeungnam University, Gyeongsan, Korea
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106
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Lv C, Wu C, Zhou YH, Shao Y, Wang G, Wang QY. Alpha Lipoic Acid Modulated High Glucose-Induced Rat Mesangial Cell Dysfunction via mTOR/p70S6K/4E-BP1 Pathway. Int J Endocrinol 2014; 2014:658589. [PMID: 25530759 PMCID: PMC4229972 DOI: 10.1155/2014/658589] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Revised: 10/07/2014] [Accepted: 10/08/2014] [Indexed: 01/09/2023] Open
Abstract
The aim of this study was to investigate whether alpha lipoic acid (LA) regulates high glucose-induced mesangial cell proliferation and extracellular matrix production via mTOR/p70S6K/4E-BP1 signaling. The effect of LA on high glucose-induced cell proliferation, fibronectin (FN), and collagen type I (collagen-I) expression and its mechanisms were examined in cultured rat mesangial cells by methylthiazol tetrazolium (MTT) assay, flow cytometry, ELISA assay, and western blot, respectively. LA at a relatively low concentration (0.25 mmol/L) acted as a growth factor in rat mesangial cells, promoted entry of cell cycle into S phase, extracellular matrix formation, and phosphorylated AKT, mTOR, p70S6K, and 4E-BP1. These effects disappeared when AKT expression was downregulated with PI3K/AKT inhibitor LY294002. Conversely, LA at a higher concentration (1.0 mmol/L) inhibited high glucose-induced rat mesangial cell proliferation, entry of cell cycle into S phase, and extracellular matrix exertion, as well as phosphorylation of mTOR, p70S6K, and 4E-BP1 but enhanced the activity of AMPK. However, these effects disappeared when AMPK activity was inhibited with CaMKK inhibitor STO-609. These results suggest that LA dose-dependently regulates mesangial cell proliferation and matrix protein secretion by mTOR/p70S6K/4E-BP1 signaling pathway under high glucose conditions.
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Affiliation(s)
- Chuan Lv
- Division of Endocrinology, First Affiliated Hospital, China Medical University, Shenyang, Liaoning 110001, China
| | - Can Wu
- Division of Endocrinology, First Affiliated Hospital, China Medical University, Shenyang, Liaoning 110001, China
| | - Yue-hong Zhou
- Division of Endocrinology, Shenyang No. 8 Hospital, Shenyang, Liaoning 110024, China
| | - Ying Shao
- Division of Endocrinology, First Affiliated Hospital, China Medical University, Shenyang, Liaoning 110001, China
| | - Guan Wang
- Clinical Medicine of Seven-Year Education, China Medical University, Shenyang, Liaoning 110001, China
| | - Qiu-yue Wang
- Division of Endocrinology, First Affiliated Hospital, China Medical University, Shenyang, Liaoning 110001, China
- *Qiu-yue Wang:
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107
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Soetikno V, Arozal W, Louisa M, Setiabudy R. New insight into the molecular drug target of diabetic nephropathy. Int J Endocrinol 2014; 2014:968681. [PMID: 24648839 PMCID: PMC3932220 DOI: 10.1155/2014/968681] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2013] [Revised: 11/29/2013] [Accepted: 12/23/2013] [Indexed: 01/07/2023] Open
Abstract
Diabetic nephropathy (DN) lowered quality of life and shortened life expectancy amongst those affected. Evidence indicates interaction between advanced glycation end products (AGEs), activated protein kinase C (PKC) and angiotensin II exacerbate the progression of DN. Inhibitors of angiotensin-converting enzyme (ACEIs), renin angiotensin aldosterone system (RAAS), AGEs, and PKC have been tested for slowing down the progression of DN. The exact molecular drug targets that lead to the amelioration of renal injury in DN are not well understood. This review summarizes the potential therapeutic targets, based on putative mechanism in the progression of the disease.
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Affiliation(s)
- Vivian Soetikno
- Department of Pharmacology and Therapeutic, Faculty of Medicine, University of Indonesia, Salemba Raya 6, Jakarta 10430, Indonesia
- *Vivian Soetikno:
| | - Wawaimuli Arozal
- Department of Pharmacology and Therapeutic, Faculty of Medicine, University of Indonesia, Salemba Raya 6, Jakarta 10430, Indonesia
| | - Melva Louisa
- Department of Pharmacology and Therapeutic, Faculty of Medicine, University of Indonesia, Salemba Raya 6, Jakarta 10430, Indonesia
| | - Rianto Setiabudy
- Department of Pharmacology and Therapeutic, Faculty of Medicine, University of Indonesia, Salemba Raya 6, Jakarta 10430, Indonesia
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108
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Das R, Xu S, Quan X, Nguyen TT, Kong ID, Chung CH, Lee EY, Cha SK, Park KS. Upregulation of mitochondrial Nox4 mediates TGF-β-induced apoptosis in cultured mouse podocytes. Am J Physiol Renal Physiol 2013; 306:F155-67. [PMID: 24259511 DOI: 10.1152/ajprenal.00438.2013] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Injury to podocytes leads to the onset of chronic renal diseases characterized by proteinuria. Elevated transforming growth factor (TGF)-β in kidney tissue is associated with podocyte damage that ultimately results in apoptosis and detachment. We investigated the proapoptotic mechanism of TGF-β in immortalized mouse podocytes. Exogenous TGF-β1-induced podocyte apoptosis through caspase-3 activation, which was related to elevated ROS levels generated by selective upregulation of NADPH oxidase 4 (Nox4). In mouse podocytes, Nox4 was predominantly localized to mitochondria, and Nox4 upregulation by TGF-β1 markedly depolarized mitochondrial membrane potential. TGF-β1-induced ROS production and caspase activation were mitigated by an antioxidant, the Nox inhibitor diphenyleneiodonium, or small interfering RNA for Nox4. A TGF-β receptor I blocker, SB-431542, completely reversed the changes triggered by TGF-β1. Knockdown of either Smad2 or Smad3 prevented the increase of Nox4 expression, ROS generation, loss of mitochondrial membrane potential, and caspase-3 activation by TGF-β1. These results suggest that TGF-β1-induced mitochondrial Nox4 upregulation via the TGF-β receptor-Smad2/3 pathway is responsible for ROS production, mitochondrial dysfunction, and apoptosis, which may at least in part contribute to the development and progression of proteinuric glomerular diseases such as diabetic nephropathy.
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Affiliation(s)
- Ranjan Das
- Dept. of Physiology and Institute of Lifestyle Medicine, Yonsei Univ. Wonju College of Medicine, Ilsan-dong, Wonju, Gangwon-Do 220-701, Republic of Korea.
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109
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Mao S, Huang S. The signaling pathway of NADPH oxidase and its role in glomerular diseases. J Recept Signal Transduct Res 2013; 34:6-11. [PMID: 24156279 DOI: 10.3109/10799893.2013.848892] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (Nox), a major source of reactive oxygen species, is a critical mediator of redox signaling. It is well-documented that oxidative stress is associated with the development of glomerular diseases (GN). Hence, the Nox was also thought to be involved in the pathogenesis of GN. However, the expression of Nox in various GN was not consistent, the mechanisms by which the activity of the Nox enzymes in regulating renal cells remains unclear. Signaling pathways might be very important in the pathogenesis of GN. We performed this review to provide a relatively complete signaling pathways flowchart for Nox to the investigators who were interested in the role of Nox in the pathogenesis of GN. Here, we reviewed the signal transduction pathway of Nox and its role in the pathogenesis of GN.
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Affiliation(s)
- Song Mao
- Department of Nephrology, Nanjing Children's Hospital, Nanjing Medical University , Nanjing , People's Republic of China
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110
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Abstract
Oxidative stress has been linked to the pathogenesis of the major complications of diabetes in the kidney, the heart, the eye or the vasculature. NADPH oxidases of the Nox family are a major source of ROS (reactive oxygen species) and are critical mediators of redox signalling in cells from different organs afflicted by the diabetic milieu. In the present review, we provide an overview of the current knowledge related to the understanding of the role of Nox in the processes that control cell injury induced by hyperglycaemia and other predominant factors enhanced in diabetes, including the renin–angiotensin system, TGF-β (transforming growth factor-β) and AGEs (advanced glycation end-products). These observations support a critical role for Nox homologues in diabetic complications and indicate that NADPH oxidases are an important therapeutic target. Therefore the design and development of small-molecule inhibitors that selectively block Nox oxidases appears to be a reasonable approach to prevent or retard the complications of diabetes in target organs. The bioefficacy of these agents in experimental animal models is also discussed in the present review.
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111
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mTOR and podocyte apoptosis in diabetic nephropathy. Nat Rev Nephrol 2013. [DOI: 10.1038/nrneph.2013.64] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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