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Prieto-Bermejo R, Hernández-Hernández A. The Importance of NADPH Oxidases and Redox Signaling in Angiogenesis. Antioxidants (Basel) 2017; 6:antiox6020032. [PMID: 28505091 PMCID: PMC5488012 DOI: 10.3390/antiox6020032] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Revised: 04/28/2017] [Accepted: 05/11/2017] [Indexed: 02/06/2023] Open
Abstract
Eukaryotic cells have to cope with the constant generation of reactive oxygen species (ROS). Although the excessive production of ROS might be deleterious for cell biology, there is a plethora of evidence showing that moderate levels of ROS are important for the control of cell signaling and gene expression. The family of the nicotinamide adenine dinucleotide phosphate oxidases (NADPH oxidases or Nox) has evolved to produce ROS in response to different signals; therefore, they fulfil a central role in the control of redox signaling. The role of NADPH oxidases in vascular physiology has been a field of intense study over the last two decades. In this review we will briefly analyze how ROS can regulate signaling and gene expression. We will address the implication of NADPH oxidases and redox signaling in angiogenesis, and finally, the therapeutic possibilities derived from this knowledge will be discussed.
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Affiliation(s)
- Rodrigo Prieto-Bermejo
- Department of Biochemistry and Molecular Biology, University of Salamanca, Salamanca 37007, Spain.
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52
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Oxidative stress and calcium dysregulation by palmitate in type 2 diabetes. Exp Mol Med 2017; 49:e291. [PMID: 28154371 PMCID: PMC5336562 DOI: 10.1038/emm.2016.157] [Citation(s) in RCA: 217] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Revised: 10/07/2016] [Accepted: 10/16/2016] [Indexed: 12/12/2022] Open
Abstract
Free fatty acids (FFAs) are important substrates for mitochondrial oxidative metabolism and ATP synthesis but also cause serious stress to various tissues, contributing to the development of metabolic diseases. CD36 is a major mediator of cellular FFA uptake. Inside the cell, saturated FFAs are able to induce the production of cytosolic and mitochondrial reactive oxygen species (ROS), which can be prevented by co-exposure to unsaturated FFAs. There are close connections between oxidative stress and organellar Ca2+ homeostasis. Highly oxidative conditions induced by palmitate trigger aberrant endoplasmic reticulum (ER) Ca2+ release and thereby deplete ER Ca2+ stores. The resulting ER Ca2+ deficiency impairs chaperones of the protein folding machinery, leading to the accumulation of misfolded proteins. This ER stress may further aggravate oxidative stress by augmenting ER ROS production. Secondary to ER Ca2+ release, cytosolic and mitochondrial matrix Ca2+ concentrations can also be altered. In addition, plasmalemmal ion channels operated by ER Ca2+ depletion mediate persistent Ca2+ influx, further impairing cytosolic and mitochondrial Ca2+ homeostasis. Mitochondrial Ca2+ overload causes superoxide production and functional impairment, culminating in apoptosis. This vicious cycle of lipotoxicity occurs in multiple tissues, resulting in β-cell failure and insulin resistance in target tissues, and further aggravates diabetic complications.
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53
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Massip-Copiz MM, Clauzure M, Valdivieso ÁG, Santa-Coloma TA. CFTR impairment upregulates c-Src activity through IL-1β autocrine signaling. Arch Biochem Biophys 2017; 616:1-12. [PMID: 28088327 DOI: 10.1016/j.abb.2017.01.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Revised: 01/06/2017] [Accepted: 01/09/2017] [Indexed: 12/24/2022]
Abstract
Cystic Fibrosis (CF) is a disease caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Previously, we found several genes showing a differential expression in CFDE cells (epithelial cells derived from a CF patient). One corresponded to c-Src; its expression and activity was found increased in CFDE cells, acting as a signaling molecule between the CFTR activity and MUC1 overexpression. Here we report that bronchial IB3-1 cells (CF cells) also showed increased c-Src activity compared to 'CFTR-corrected' S9 cells. In addition, three different Caco-2 cell lines, each stably transfected with a different CFTR-specific shRNAs, displayed increased c-Src activity. The IL-1β receptor antagonist IL1RN reduced the c-Src activity of Caco-2/pRS26 cells (expressing a CFTR-specific shRNA). In addition, increased mitochondrial and cellular ROS levels were detected in Caco-2/pRS26 cells. ROS levels were partially reduced by incubation with PP2 (c-Src inhibitor) or IL1RN, and further reduced by using the NOX1/4 inhibitor GKT137831. Thus, IL-1β→c-Src and IL-1β→NOX signaling pathways appear to be responsible for the production of cellular and mitochondrial ROS in CFTR-KD cells. In conclusion, IL-1β constitutes a new step in the CFTR signaling pathway, located upstream of c-Src, which is stimulated in cells with impaired CFTR activity.
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Affiliation(s)
- María Macarena Massip-Copiz
- Laboratory of Cellular and Molecular Biology, Institute for Biomedical Research (BIOMED), School of Medical Sciences, Pontifical Catholic University of Argentina (UCA), National Scientific and Technical Research Council (CONICET), Buenos Aires, Argentina
| | - Mariángeles Clauzure
- Laboratory of Cellular and Molecular Biology, Institute for Biomedical Research (BIOMED), School of Medical Sciences, Pontifical Catholic University of Argentina (UCA), National Scientific and Technical Research Council (CONICET), Buenos Aires, Argentina
| | - Ángel Gabriel Valdivieso
- Laboratory of Cellular and Molecular Biology, Institute for Biomedical Research (BIOMED), School of Medical Sciences, Pontifical Catholic University of Argentina (UCA), National Scientific and Technical Research Council (CONICET), Buenos Aires, Argentina
| | - Tomás Antonio Santa-Coloma
- Laboratory of Cellular and Molecular Biology, Institute for Biomedical Research (BIOMED), School of Medical Sciences, Pontifical Catholic University of Argentina (UCA), National Scientific and Technical Research Council (CONICET), Buenos Aires, Argentina.
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54
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Fakhruddin S, Alanazi W, Jackson KE. Diabetes-Induced Reactive Oxygen Species: Mechanism of Their Generation and Role in Renal Injury. J Diabetes Res 2017; 2017:8379327. [PMID: 28164134 PMCID: PMC5253173 DOI: 10.1155/2017/8379327] [Citation(s) in RCA: 165] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Accepted: 12/07/2016] [Indexed: 02/07/2023] Open
Abstract
Diabetes induces the onset and progression of renal injury through causing hemodynamic dysregulation along with abnormal morphological and functional nephron changes. The most important event that precedes renal injury is an increase in permeability of plasma proteins such as albumin through a damaged glomerular filtration barrier resulting in excessive urinary albumin excretion (UAE). Moreover, once enhanced UAE begins, it may advance renal injury from progression of abnormal renal hemodynamics, increased glomerular basement membrane (GBM) thickness, mesangial expansion, extracellular matrix accumulation, and glomerulosclerosis to eventual end-stage renal damage. Interestingly, all these pathological changes are predominantly driven by diabetes-induced reactive oxygen species (ROS) and abnormal downstream signaling molecules. In diabetic kidney, NADPH oxidase (enzymatic) and mitochondrial electron transport chain (nonenzymatic) are the prominent sources of ROS, which are believed to cause the onset of albuminuria followed by progression to renal damage through podocyte depletion. Chronic hyperglycemia and consequent ROS production can trigger abnormal signaling pathways involving diverse signaling mediators such as transcription factors, inflammatory cytokines, chemokines, and vasoactive substances. Persistently, increased expression and activation of these signaling molecules contribute to the irreversible functional and structural changes in the kidney resulting in critically decreased glomerular filtration rate leading to eventual renal failure.
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Affiliation(s)
- Selim Fakhruddin
- Department of Basic Pharmaceutical Sciences, School of Pharmacy, University of Louisiana at Monroe (ULM), Pharmacy Building, 1800 Bienville Dr., Monroe, LA 71201, USA
| | - Wael Alanazi
- Department of Basic Pharmaceutical Sciences, School of Pharmacy, University of Louisiana at Monroe (ULM), Pharmacy Building, 1800 Bienville Dr., Monroe, LA 71201, USA
| | - Keith E. Jackson
- Department of Basic Pharmaceutical Sciences, School of Pharmacy, University of Louisiana at Monroe (ULM), Pharmacy Building, 1800 Bienville Dr., Monroe, LA 71201, USA
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55
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Kim JH, Xie J, Hwang KH, Wu YL, Oliver N, Eom M, Park KS, Barrezueta N, Kong ID, Fracasso RP, Huang CL, Cha SK. Klotho May Ameliorate Proteinuria by Targeting TRPC6 Channels in Podocytes. J Am Soc Nephrol 2017; 28:140-151. [PMID: 27151926 PMCID: PMC5198269 DOI: 10.1681/asn.2015080888] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Accepted: 03/18/2016] [Indexed: 12/30/2022] Open
Abstract
Klotho is a type-1 membrane protein predominantly produced in the kidney, the extracellular domain of which is secreted into the systemic circulation. Membranous and secreted Klotho protect organs, including the kidney, but whether and how Klotho directly protects the glomerular filter is unknown. Here, we report that secreted Klotho suppressed transient receptor potential channel 6 (TRPC6)-mediated Ca2+ influx in cultured mouse podocytes by inhibiting phosphoinositide 3-kinase-dependent exocytosis of the channel. Furthermore, soluble Klotho reduced ATP-stimulated actin cytoskeletal remodeling and transepithelial albumin leakage in these cells. Overexpression of TRPC6 by gene delivery in mice induced albuminuria, and exogenous administration of Klotho ameliorated the albuminuria. Notably, immunofluorescence and in situ hybridization revealed Klotho expression in podocytes of mouse and human kidney. Heterozygous Klotho-deficient CKD mice had aggravated albuminuria compared with that in wild-type CKD mice with a similar degree of hypertension and reduced clearance function. Finally, disrupting the integrity of glomerular filter by saline infusion-mediated extracellular fluid volume expansion increased urinary Klotho excretion. These results reveal a potential novel function of Klotho in protecting the glomerular filter, and may offer a new therapeutic strategy for treatment of proteinuria.
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Affiliation(s)
- Ji-Hee Kim
- Departments of Physiology and Global Medical Science
| | - Jian Xie
- Division of Nephrology, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Kyu-Hee Hwang
- Departments of Physiology and Global Medical Science
| | - Yueh-Lin Wu
- Division of Nephrology, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
- Division of Nephrology, Department of Internal Medicine, Taipei Medical University Hospital, Taipei, Taiwan; and
| | - Noelynn Oliver
- Cardiometabolic Disease Research, Boehringer Ingelheim Pharmaceuticals Inc., Ridgefield, Connecticut
| | | | - Kyu-Sang Park
- Departments of Physiology and Global Medical Science
- Institute of Lifestyle Medicine, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea
| | - Nestor Barrezueta
- Cardiometabolic Disease Research, Boehringer Ingelheim Pharmaceuticals Inc., Ridgefield, Connecticut
| | - In-Deok Kong
- Departments of Physiology and Global Medical Science
- Institute of Lifestyle Medicine, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea
| | - R Paul Fracasso
- Cardiometabolic Disease Research, Boehringer Ingelheim Pharmaceuticals Inc., Ridgefield, Connecticut
| | - Chou-Long Huang
- Division of Nephrology, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas;
| | - Seung-Kuy Cha
- Departments of Physiology and Global Medical Science,
- Institute of Lifestyle Medicine, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea
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56
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Hermle T, Braun DA, Helmstädter M, Huber TB, Hildebrandt F. Modeling Monogenic Human Nephrotic Syndrome in the Drosophila Garland Cell Nephrocyte. J Am Soc Nephrol 2016; 28:1521-1533. [PMID: 27932481 DOI: 10.1681/asn.2016050517] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Accepted: 11/05/2016] [Indexed: 11/03/2022] Open
Abstract
Steroid-resistant nephrotic syndrome is characterized by podocyte dysfunction. Drosophila garland cell nephrocytes are podocyte-like cells and thus provide a potential in vivo model in which to study the pathogenesis of nephrotic syndrome. However, relevant pathomechanisms of nephrotic syndrome have not been studied in nephrocytes. Here, we discovered that two Drosophila slit diaphragm proteins, orthologs of the human genes encoding nephrin and nephrin-like protein 1, colocalize within a fingerprint-like staining pattern that correlates with ultrastructural morphology. Using RNAi and conditional CRISPR/Cas9 in nephrocytes, we found this pattern depends on the expression of both orthologs. Tracer endocytosis by nephrocytes required Cubilin and reflected size selectivity analogous to that of glomerular function. Using RNAi and tracer endocytosis as a functional read-out, we screened Drosophila orthologs of human monogenic causes of nephrotic syndrome and observed conservation of the central pathogenetic alterations. We focused on the coenzyme Q10 (CoQ10) biosynthesis gene Coq2, the silencing of which disrupted slit diaphragm morphology. Restoration of CoQ10 synthesis by vanillic acid partially rescued the phenotypic and functional alterations induced by Coq2-RNAi. Notably, Coq2 colocalized with mitochondria, and Coq2 silencing increased the formation of reactive oxygen species (ROS). Silencing of ND75, a subunit of the mitochondrial respiratory chain that controls ROS formation independently of CoQ10, phenocopied the effect of Coq2-RNAi. Moreover, the ROS scavenger glutathione partially rescued the effects of Coq2-RNAi. In conclusion, Drosophila garland cell nephrocytes provide a model with which to study the pathogenesis of nephrotic syndrome, and ROS formation may be a pathomechanism of COQ2-nephropathy.
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Affiliation(s)
- Tobias Hermle
- Division of Nephrology, Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts;
| | - Daniela A Braun
- Division of Nephrology, Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Martin Helmstädter
- Renal Division, University Medical Center Freiburg, Freiburg, Germany, Faculty of Medicine, University of Freiburg, Freiburg, Germany; and
| | - Tobias B Huber
- Renal Division, University Medical Center Freiburg, Freiburg, Germany, Faculty of Medicine, University of Freiburg, Freiburg, Germany; and.,BIOSS Center for Biological Signalling Studies, Albert-Ludwigs-University Freiburg, Freiburg, Germany
| | - Friedhelm Hildebrandt
- Division of Nephrology, Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts;
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57
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NADPH oxidase 4 deficiency increases tubular cell death during acute ischemic reperfusion injury. Sci Rep 2016; 6:38598. [PMID: 27924932 PMCID: PMC5141508 DOI: 10.1038/srep38598] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Accepted: 11/10/2016] [Indexed: 12/13/2022] Open
Abstract
NADPH oxidase 4 (NOX4) is highly expressed in kidney proximal tubular cells. NOX4 constitutively produces hydrogen peroxide, which may regulate important pro-survival pathways. Renal ischemia reperfusion injury (IRI) is a classical model mimicking human ischemic acute tubular necrosis. We hypothesized that NOX4 plays a protective role in kidney IRI. In wild type (WT) animals subjected to IRI, NOX4 protein expression increased after 24 hours. NOX4 KO (knock-out) and WT littermates mice were subjected to IRI. NOX4 KO mice displayed decreased renal function and more severe tubular apoptosis, decreased Bcl-2 expression and higher histologic damage scores compared to WT. Activation of NRF2 was decreased in NOX4 KO mice in response to IRI. This was related to decreased KEAP1 oxidation leading to decreased NRF2 stabilization. This resulted in decreased glutathione levels. In vitro silencing of NOX4 in cells showed an enhanced propensity to apoptosis, with reduced expression of NRF2, glutathione content and Bcl-2 expression, similar to cells derived from NOX4 KO mice. Overexpression of a constitutively active form of NRF2 (caNRF2) in NOX4 depleted cells rescued most of this phenotype in cultured cells, implying that NRF2 regulation by ROS issued from NOX4 may play an important role in its anti-apoptotic property.
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58
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Jha JC, Banal C, Chow BSM, Cooper ME, Jandeleit-Dahm K. Diabetes and Kidney Disease: Role of Oxidative Stress. Antioxid Redox Signal 2016; 25:657-684. [PMID: 26906673 PMCID: PMC5069735 DOI: 10.1089/ars.2016.6664] [Citation(s) in RCA: 385] [Impact Index Per Article: 48.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Intrarenal oxidative stress plays a critical role in the initiation and progression of diabetic kidney disease (DKD). Enhanced oxidative stress results from overproduction of reactive oxygen species (ROS) in the context of concomitant, insufficient antioxidant pathways. Renal ROS production in diabetes is predominantly mediated by various NADPH oxidases (NOXs), but a defective antioxidant system as well as mitochondrial dysfunction may also contribute. Recent Advances: Effective agents targeting the source of ROS generation hold the promise to rescue the kidney from oxidative damage and prevent subsequent progression of DKD. Critical Issues and Future Directions: In the present review, we summarize and critically analyze molecular and cellular mechanisms that have been demonstrated to be involved in NOX-induced renal injury in diabetes, with particular focus on the role of increased glomerular injury, the development of albuminuria, and tubulointerstitial fibrosis, as well as mitochondrial dysfunction. Furthermore, novel agents targeting NOX isoforms are discussed. Antioxid. Redox Signal. 25, 657-684.
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Affiliation(s)
- Jay C Jha
- 1 Diabetic Complications Division, JDRF Danielle Alberti Memorial Centre for Diabetic Complications, Baker IDI Heart and Diabetes Institute , Melbourne, Australia
| | - Claudine Banal
- 1 Diabetic Complications Division, JDRF Danielle Alberti Memorial Centre for Diabetic Complications, Baker IDI Heart and Diabetes Institute , Melbourne, Australia
| | - Bryna S M Chow
- 1 Diabetic Complications Division, JDRF Danielle Alberti Memorial Centre for Diabetic Complications, Baker IDI Heart and Diabetes Institute , Melbourne, Australia
| | - Mark E Cooper
- 1 Diabetic Complications Division, JDRF Danielle Alberti Memorial Centre for Diabetic Complications, Baker IDI Heart and Diabetes Institute , Melbourne, Australia .,2 Department of Medicine, Monash University , Melbourne, Australia
| | - Karin Jandeleit-Dahm
- 1 Diabetic Complications Division, JDRF Danielle Alberti Memorial Centre for Diabetic Complications, Baker IDI Heart and Diabetes Institute , Melbourne, Australia .,2 Department of Medicine, Monash University , Melbourne, Australia
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59
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Role of NADPH Oxidase in Metabolic Disease-Related Renal Injury: An Update. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2016; 2016:7813072. [PMID: 27597884 PMCID: PMC5002489 DOI: 10.1155/2016/7813072] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Accepted: 07/17/2016] [Indexed: 01/09/2023]
Abstract
Metabolic syndrome has been linked to an increased risk of chronic kidney disease. The underlying pathogenesis of metabolic disease-related renal injury remains obscure. Accumulating evidence has shown that NADPH oxidase is a major source of intrarenal oxidative stress and is upregulated by metabolic factors leading to overproduction of ROS in podocytes, endothelial cells, and mesangial cells in glomeruli, which is closely associated with the initiation and progression of glomerular diseases. This review focuses on the role of NADPH oxidase-induced oxidative stress in the pathogenesis of metabolic disease-related renal injury. Understanding of the mechanism may help find potential therapeutic strategies.
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60
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Anti-TGF-β Antibody, 1D11, Ameliorates Glomerular Fibrosis in Mouse Models after the Onset of Proteinuria. PLoS One 2016; 11:e0155534. [PMID: 27187580 PMCID: PMC4871338 DOI: 10.1371/journal.pone.0155534] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Accepted: 04/29/2016] [Indexed: 12/20/2022] Open
Abstract
Fibrosis is a final common pathway leading to loss of kidney function, in which the fibrogenic cytokine, transforming growth factor β (TGF-β), plays a central role. While previous studies showed that TGF-β antagonism by various means prevents fibrosis in mouse models, clinical approaches based on these findings remain elusive. 1D11 is a neutralizing antibody to all three isoforms of TGF-β. In both adriamycin (ADR)-induced nephropathy and NEP25 podocyte ablation nephropathy, thrice-weekly intraperitoneal administration of 1D11 from the day of disease induction until the mice were sacrificed (day 14 for ADR and day 28 for NEP25), significantly reduced glomerular COL1A2 mRNA accumulation and histological changes. Consistent with our previous findings, proteinuria remained overt in the mice treated with 1D11, suggesting distinct mechanisms for proteinuria and fibrogenesis. Podocyte numbers determined by WT1 staining were significantly reduced in NEP25-model glomeruli as expected, while WT1-positive cells were preserved in mice receiving 1D11. Even when 1D11 was administered after the onset of proteinuria on day 3, 1D11 preserved WT1-positive cell numbers in glomeruli and significantly reduced glomerular scar score (2.5 ± 0.2 [control IgG] vs. 1.8 ± 0.2 [1D11], P < 0.05) and glomerular COL1A2 mRNA expression (19.3 ± 4.4 [control IgG] vs. 8.4 ± 2.4 [1D11] fold increase over the healthy control, P < 0.05). Transmission electron microscopy revealed loss of podocytes and denuded glomerular basement membrane in NEP25 mice with disease, whereas podocytes remained attached to the basement membrane, though effaced and swollen, in those receiving 1D11 from day 3. Together, these data suggest that TGF-β neutralization by 1D11 prevents glomerular fibrosis even when started after the onset of proteinuria. While overt proteinuria and podocyte effacement persist, 1D11 prevents total podocytes detachment, which might be a key event activating fibrogenic events in glomeruli.
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Abstract
Diabetes is increasing in prevalence and is the leading cause of end-stage renal disease in the United States. Diabetic kidney disease is considered a proteinuric glomerular disease. Although the glomerulus is composed of various cell types, research suggests that podocytes are critical to overall glomerular health. Podocyte injury has been identified as a pivotal event resulting in proteinuric kidney disease, glomerulosclerosis, and loss of renal function. Thus, understanding the signaling mechanisms that trigger podocyte injury in diabetic kidney disease might allow for the development of targeted therapeutics to prevent or ameliorate progression to end-stage renal failure. This review focuses on the role of podocytes in diabetic kidney disease.
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Affiliation(s)
- Jamie S Lin
- Renal-Electrolyte and Hypertension Division, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Katalin Susztak
- Renal-Electrolyte and Hypertension Division, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA.
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62
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Abstract
Transforming growth factor-β (TGF-β) is the primary factor that drives fibrosis in most, if not all, forms of chronic kidney disease (CKD). Inhibition of the TGF-β isoform, TGF-β1, or its downstream signalling pathways substantially limits renal fibrosis in a wide range of disease models whereas overexpression of TGF-β1 induces renal fibrosis. TGF-β1 can induce renal fibrosis via activation of both canonical (Smad-based) and non-canonical (non-Smad-based) signalling pathways, which result in activation of myofibroblasts, excessive production of extracellular matrix (ECM) and inhibition of ECM degradation. The role of Smad proteins in the regulation of fibrosis is complex, with competing profibrotic and antifibrotic actions (including in the regulation of mesenchymal transitioning), and with complex interplay between TGF-β/Smads and other signalling pathways. Studies over the past 5 years have identified additional mechanisms that regulate the action of TGF-β1/Smad signalling in fibrosis, including short and long noncoding RNA molecules and epigenetic modifications of DNA and histone proteins. Although direct targeting of TGF-β1 is unlikely to yield a viable antifibrotic therapy due to the involvement of TGF-β1 in other processes, greater understanding of the various pathways by which TGF-β1 controls fibrosis has identified alternative targets for the development of novel therapeutics to halt this most damaging process in CKD.
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63
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Gao F, Yao M, Cao Y, Liu S, Liu Q, Duan H. Valsartan ameliorates podocyte loss in diabetic mice through the Notch pathway. Int J Mol Med 2016; 37:1328-36. [PMID: 26985716 DOI: 10.3892/ijmm.2016.2525] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Accepted: 03/01/2016] [Indexed: 11/06/2022] Open
Abstract
The Notch pathway is known to be linked to diabetic nephropathy (DN); however, its underlying mechanism was poorly understood. In the present study, we examined the effect of Valsartan, an angiotensin II type 1 receptor antagonist, on the Notch pathway and podocyte loss in DN. Diabetes was induced in mice by an intraperitoneal injection of streptozotocin and and this was followed by treatment with Valsartan. Levels of blood glucose, kidney weight and body weight, as well as proteinuria were measured. Samples of the kidneys were also histologically examined. The relative levels of Jagged1, Notch1, Notch intracellular domain 1 (NICD1), Hes family BHLH transcription factor 1 (Hes1) and Hes-related family BHLH transcription factor with YRPW motif 1 expression (Hey1) in the glomeruli were determined by immunohistochemical analysis, western blot analysis and RT-qPCR. The B-Cell CLL/Lymphoma 2 (Bcl-2) and p53 pathways were examined by western blot analysis. Apoptosis and detachment of podocytes from the glomerular basement membrane were examined using a TUNEL assay, flow cytometric analysis and ELISA. The number of podocytes was quantified by measuring Wilms tumor-1 (WT-1) staining. We noted that the expression of Jagged1, Notch1, NICD1, Hes1 and Hey1 was increased in a time-dependent manner in the glomeruli of mice with streptozotocin (STZ)-induced diabetes. Moreover, in diabetic mice, Valsartan significantly reduced kidney weight and proteinuria, and mitigated the pathogenic processes in the kidneys. Valsartan also inhibited the activation of Notch, Bcl-2 and p53 pathways and ameliorated podocyte loss in the glomeruli of mice with STZ-induced diabetes. Taken together, these findings indicated that Valsartan exerted a beneficial effect on reducing podocyte loss, which is associated with inhibition of Notch pathway activation in the glomeruli of diabetic mice.
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Affiliation(s)
- Feng Gao
- Department of Pathology, Hebei Medical University, Shijiazhuang, Hebei 050017, P.R. China
| | - Min Yao
- Department of Biochemistry, Hebei Medical University, Shijiazhuang, Hebei 050017, P.R. China
| | - Yanping Cao
- Department of Pathology, Hebei Medical University, Shijiazhuang, Hebei 050017, P.R. China
| | - Shuxia Liu
- Department of Pathology, Hebei Medical University, Shijiazhuang, Hebei 050017, P.R. China
| | - Qingjuan Liu
- Department of Pathology, Hebei Medical University, Shijiazhuang, Hebei 050017, P.R. China
| | - Huijun Duan
- Department of Pathology, Hebei Medical University, Shijiazhuang, Hebei 050017, P.R. China
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Abstract
Podocytes are highly specialized cells of the kidney glomerulus that wrap around capillaries and that neighbor cells of the Bowman’s capsule. When it comes to glomerular filtration, podocytes play an active role in preventing plasma proteins from entering the urinary ultrafiltrate by providing a barrier comprising filtration slits between foot processes, which in aggregate represent a dynamic network of cellular extensions. Foot processes interdigitate with foot processes from adjacent podocytes and form a network of narrow and rather uniform gaps. The fenestrated endothelial cells retain blood cells but permit passage of small solutes and an overlying basement membrane less permeable to macromolecules, in particular to albumin. The cytoskeletal dynamics and structural plasticity of podocytes as well as the signaling between each of these distinct layers are essential for an efficient glomerular filtration and thus for proper renal function. The genetic or acquired impairment of podocytes may lead to foot process effacement (podocyte fusion or retraction), a morphological hallmark of proteinuric renal diseases. Here, we briefly discuss aspects of a contemporary view of podocytes in glomerular filtration, the patterns of structural changes in podocytes associated with common glomerular diseases, and the current state of basic and clinical research.
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Affiliation(s)
- Jochen Reiser
- Department of Medicine, Rush University Medical Center, Chicago, IL, USA
| | - Mehmet M Altintas
- Department of Medicine, Rush University Medical Center, Chicago, IL, USA
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65
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Casalena G, Bottinger E, Daehn I. TGFβ-Induced Actin Cytoskeleton Rearrangement in Podocytes Is Associated with Compensatory Adaptation of Mitochondrial Energy Metabolism. Nephron Clin Pract 2015; 131:278-84. [PMID: 26613578 DOI: 10.1159/000442051] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2014] [Accepted: 11/01/2015] [Indexed: 01/24/2023] Open
Abstract
BACKGROUND/AIMS In podocytes, the overexpression of TGFβ ligands and receptors during glomerulosclerosis could be a causal factor for injury induction and perpetuation in glomerular tufts. Mitochondrial dysfunction and oxidative stress are emerging as potential therapeutic targets in glomerular injury, and TGFβ has been shown to modulate mitochondrial metabolism in different cell types. This study aims at investigating the role of TGFβ in podocyte energy metabolism and cytoskeleton dynamics. METHODS Mitochondrial function and cytoskeleton dynamics were analyzed in TGFβ-treated WT and Smad2/3 double KO podocytes. RESULTS TGFβ treatment in podocytes induced a significant Smad-dependent increase of mitochondrial oxygen consumption rate (OCR). ATP content was unchanged and increased respiration was not associated with increased mitochondrial mass. Increased cellular reactive oxygen species induced by Smad-mediated TGFβ signaling were reverted by NADPH oxidase inhibitor apocynin. TGFβ treatment did not induce mitochondrial oxidative stress, and Smad2/3-dependent TGFβ signaling and increased mitochondrial OCR were found to be associated with actin cytoskeleton dynamics. The role of motor proteins myosin II and dynamin in TGFβ-induced actin polymerization was demonstrated by specific inhibition, resulting in actin stabilization and normalization of mitochondrial OCR. CONCLUSION TGFβ-induced rearrangements of actin cytoskeleton are controlled by Smad2/3 signaling pathways and coupled with the activation of mitochondrial ATP synthesis as bioenergetic adaptation to ATP consumption by ATP- and GTP-dependent motor proteins, myosin II and dynamin.
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Affiliation(s)
- Gabriella Casalena
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, N.Y., USA
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Xu S, Nam SM, Kim JH, Das R, Choi SK, Nguyen TT, Quan X, Choi SJ, Chung CH, Lee EY, Lee IK, Wiederkehr A, Wollheim CB, Cha SK, Park KS. Palmitate induces ER calcium depletion and apoptosis in mouse podocytes subsequent to mitochondrial oxidative stress. Cell Death Dis 2015; 6:e1976. [PMID: 26583319 PMCID: PMC4670935 DOI: 10.1038/cddis.2015.331] [Citation(s) in RCA: 135] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Revised: 10/02/2015] [Accepted: 10/12/2015] [Indexed: 12/14/2022]
Abstract
Pathologic alterations in podocytes lead to failure of an essential component of the glomerular filtration barrier and proteinuria in chronic kidney diseases. Elevated levels of saturated free fatty acid (FFA) are harmful to various tissues, implemented in the progression of diabetes and its complications such as proteinuria in diabetic nephropathy. Here, we investigated the molecular mechanism of palmitate cytotoxicity in cultured mouse podocytes. Incubation with palmitate dose-dependently increased cytosolic and mitochondrial reactive oxygen species, depolarized the mitochondrial membrane potential, impaired ATP synthesis and elicited apoptotic cell death. Palmitate not only evoked mitochondrial fragmentation but also caused marked dilation of the endoplasmic reticulum (ER). Consistently, palmitate upregulated ER stress proteins, oligomerized stromal interaction molecule 1 (STIM1) in the subplasmalemmal ER membrane, abolished the cyclopiazonic acid-induced cytosolic Ca2+ increase due to depletion of luminal ER Ca2+. Palmitate-induced ER Ca2+ depletion and cytotoxicity were blocked by a selective inhibitor of the fatty-acid transporter FAT/CD36. Loss of the ER Ca2+ pool induced by palmitate was reverted by the phospholipase C (PLC) inhibitor edelfosine. Palmitate-dependent activation of PLC was further demonstrated by following cytosolic translocation of the pleckstrin homology domain of PLC in palmitate-treated podocytes. An inhibitor of diacylglycerol (DAG) kinase, which elevates cytosolic DAG, strongly promoted ER Ca2+ depletion by low-dose palmitate. GF109203X, a PKC inhibitor, partially prevented palmitate-induced ER Ca2+ loss. Remarkably, the mitochondrial antioxidant mitoTEMPO inhibited palmitate-induced PLC activation, ER Ca2+ depletion and cytotoxicity. Palmitate elicited cytoskeletal changes in podocytes and increased albumin permeability, which was also blocked by mitoTEMPO. These data suggest that oxidative stress caused by saturated FFA leads to mitochondrial dysfunction and ER Ca2+ depletion through FAT/CD36 and PLC signaling, possibly contributing to podocyte injury.
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Affiliation(s)
- S Xu
- Department of Physiology and Institute of Lifestyle Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea
| | - S M Nam
- Department of Physiology and Institute of Lifestyle Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea.,Department of Internal Medicine, Daejeon Sun Hospital, Daejeon, Korea
| | - J-H Kim
- Department of Physiology and Institute of Lifestyle Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea
| | - R Das
- Department of Physiology and Institute of Lifestyle Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea
| | - S-K Choi
- Department of Physiology and Institute of Lifestyle Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea
| | - T T Nguyen
- Department of Physiology and Institute of Lifestyle Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea
| | - X Quan
- Department of Physiology and Institute of Lifestyle Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea
| | - S J Choi
- Department of Microbiology, Yonsei University Wonju College of Medicine, Wonju, Korea
| | - C H Chung
- Department of Internal Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea
| | - E Y Lee
- Department of Internal Medicine, Soonchunhyang University Cheonan Hospital, Cheonan, Korea
| | - I-K Lee
- Department of Internal Medicine, Kyungpook National University Hospital, Daegu, Korea
| | - A Wiederkehr
- Nestlé Institute of Health Sciences, Lausanne, Switzerland
| | - C B Wollheim
- Department of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland
| | - S-K Cha
- Department of Physiology and Institute of Lifestyle Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea
| | - K-S Park
- Department of Physiology and Institute of Lifestyle Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea
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Das R, Xu S, Nguyen TT, Quan X, Choi SK, Kim SJ, Lee EY, Cha SK, Park KS. Transforming Growth Factor β1-induced Apoptosis in Podocytes via the Extracellular Signal-regulated Kinase-Mammalian Target of Rapamycin Complex 1-NADPH Oxidase 4 Axis. J Biol Chem 2015; 290:30830-42. [PMID: 26565025 DOI: 10.1074/jbc.m115.703116] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Indexed: 02/04/2023] Open
Abstract
TGF-β is a pleiotropic cytokine that accumulates during kidney injuries, resulting in various renal diseases. We have reported previously that TGF-β1 induces the selective up-regulation of mitochondrial Nox4, playing critical roles in podocyte apoptosis. Here we investigated the regulatory mechanism of Nox4 up-regulation by mTORC1 activation on TGF-β1-induced apoptosis in immortalized podocytes. TGF-β1 treatment markedly increased the phosphorylation of mammalian target of rapamycin (mTOR) and its downstream targets p70S6K and 4EBP1. Blocking TGF-β receptor I with SB431542 completely blunted the phosphorylation of mTOR, p70S6K, and 4EBP1. Transient adenoviral overexpression of mTOR-WT and constitutively active mTORΔ augmented TGF-β1-treated Nox4 expression, reactive oxygen species (ROS) generation, and apoptosis, whereas mTOR kinase-dead suppressed the above changes. In addition, knockdown of mTOR mimicked the effect of mTOR-KD. Inhibition of mTORC1 by low-dose rapamycin or knockdown of p70S6K protected podocytes through attenuation of Nox4 expression and subsequent oxidative stress-induced apoptosis by TGF-β1. Pharmacological inhibition of the MEK-ERK cascade, but not the PI3K-Akt-TSC2 pathway, abolished TGF-β1-induced mTOR activation. Inhibition of either ERK1/2 or mTORC1 did not reduce the TGF-β1-stimulated increase in Nox4 mRNA level but significantly inhibited total Nox4 expression, ROS generation, and apoptosis induced by TGF-β1. Moreover, double knockdown of Smad2 and 3 or only Smad4 completely suppressed TGF-β1-induced ERK1/2-mTORactivation. Our data suggest that TGF-β1 increases translation of Nox4 through the Smad-ERK1/2-mTORC1 axis, which is independent of transcriptional regulation. Activation of this pathway plays a crucial role in ROS generation and mitochondrial dysfunction, leading to podocyte apoptosis. Therefore, inhibition of the ERK1/2-mTORC1 pathway could be a potential therapeutic and preventive target in proteinuric and chronic kidney diseases.
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Affiliation(s)
- Ranjan Das
- From the Department of Physiology, Institute of Lifestyle Medicine, Yonsei University Wonju College of Medicine, Wonju, Gangwon-Do 220-701, Republic of Korea and
| | - Shanhua Xu
- From the Department of Physiology, Institute of Lifestyle Medicine, Yonsei University Wonju College of Medicine, Wonju, Gangwon-Do 220-701, Republic of Korea and
| | - Tuyet Thi Nguyen
- From the Department of Physiology, Institute of Lifestyle Medicine, Yonsei University Wonju College of Medicine, Wonju, Gangwon-Do 220-701, Republic of Korea and
| | - Xianglan Quan
- From the Department of Physiology, Institute of Lifestyle Medicine, Yonsei University Wonju College of Medicine, Wonju, Gangwon-Do 220-701, Republic of Korea and
| | - Seong-Kyung Choi
- From the Department of Physiology, Institute of Lifestyle Medicine, Yonsei University Wonju College of Medicine, Wonju, Gangwon-Do 220-701, Republic of Korea and
| | - Soo-Jin Kim
- From the Department of Physiology, Institute of Lifestyle Medicine, Yonsei University Wonju College of Medicine, Wonju, Gangwon-Do 220-701, Republic of Korea and
| | - Eun Young Lee
- the Department of Internal Medicine, Soonchunhyang University Cheonan Hospital, Cheonan 330-721, Republic of Korea
| | - Seung-Kuy Cha
- From the Department of Physiology, Institute of Lifestyle Medicine, Yonsei University Wonju College of Medicine, Wonju, Gangwon-Do 220-701, Republic of Korea and
| | - Kyu-Sang Park
- From the Department of Physiology, Institute of Lifestyle Medicine, Yonsei University Wonju College of Medicine, Wonju, Gangwon-Do 220-701, Republic of Korea and
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Yoshimoto T, Fujita T, Kajiya M, Matsuda S, Ouhara K, Shiba H, Kurihara H. Involvement of smad2 and Erk/Akt cascade in TGF-β1-induced apoptosis in human gingival epithelial cells. Cytokine 2015; 75:165-73. [DOI: 10.1016/j.cyto.2015.03.011] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2014] [Revised: 02/27/2015] [Accepted: 03/13/2015] [Indexed: 01/10/2023]
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Lindblom R, Higgins G, Coughlan M, de Haan JB. Targeting Mitochondria and Reactive Oxygen Species-Driven Pathogenesis in Diabetic Nephropathy. Rev Diabet Stud 2015; 12:134-56. [PMID: 26676666 DOI: 10.1900/rds.2015.12.134] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Diabetic kidney disease is one of the major microvascular complications of both type 1 and type 2 diabetes mellitus. Approximately 30% of patients with diabetes experience renal complications. Current clinical therapies can only mitigate the symptoms and delay the progression to end-stage renal disease, but not prevent or reverse it. Oxidative stress is an important player in the pathogenesis of diabetic nephropathy. The activity of reactive oxygen and nitrogen species (ROS/NS), which are by-products of the diabetic milieu, has been found to correlate with pathological changes observed in the diabetic kidney. However, many clinical studies have failed to establish that antioxidant therapy is renoprotective. The discovery that increased ROS/NS activity is linked to mitochondrial dysfunction, endoplasmic reticulum stress, inflammation, cellular senescence, and cell death calls for a refined approach to antioxidant therapy. It is becoming clear that mitochondria play a key role in the generation of ROS/NS and their consequences on the cellular pathways involved in apoptotic cell death in the diabetic kidney. Oxidative stress has also been associated with necrosis via induction of mitochondrial permeability transition. This review highlights the importance of mitochondria in regulating redox balance, modulating cellular responses to oxidative stress, and influencing cell death pathways in diabetic kidney disease. ROS/NS-mediated cellular dysfunction corresponds with progressive disease in the diabetic kidney, and consequently represents an important clinical target. Based on this consideration, this review also examines current therapeutic interventions to prevent ROS/NS-derived injury in the diabetic kidney. These interventions, mainly aimed at reducing or preventing mitochondrial-generated oxidative stress, improving mitochondrial antioxidant defense, and maintaining mitochondrial integrity, may deliver alternative approaches to halt or prevent diabetic kidney disease.
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Affiliation(s)
- Runa Lindblom
- Glycation, Nutrition and Metabolism Laboratory, Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia
| | - Gavin Higgins
- Glycation, Nutrition and Metabolism Laboratory, Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia
| | - Melinda Coughlan
- Glycation, Nutrition and Metabolism Laboratory, Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia
| | - Judy B de Haan
- Oxidative Stress Laboratory, Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia
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Abstract
PURPOSE OF REVIEW Nox-4 is a member of the NADPH oxidase (Nox) family of enzymes implicated in reactive oxygen species generation. Nox-4 is distributed in many tissues; however, its physiological functions remain poorly understood. In contrast to other Nox isoforms, it is unique in that it produces large amounts of hydrogen peroxide constitutively and does not require other cytosolic oxidase components for its activation. This review highlights the recent developments in Nox-4 research and progressive kidney disease as well as the potential of new Nox-4 inhibitors to reduce renal damage. RECENT FINDINGS Recently, Nox-4 was shown to be implicated in kidney diseases such as diabetic nephropathy. Nox-4 has been identified as playing a role in damage to the kidney induced by hyperglycaemia and other major pathways of renal damage, including advanced glycation end-products, the renin-angiotensin system, TGF-β and protein kinase C. SUMMARY The role of Nox-4 as a target for renoprotection remains controversial, although recent positive preclinical data have stimulated increased interest in inhibiting the enzyme in clinical trials of renal disease.
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71
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Liao R, Liu Q, Zheng Z, Fan J, Peng W, Kong Q, He H, Yang S, Chen W, Tang X, Yu X. Tacrolimus Protects Podocytes from Injury in Lupus Nephritis Partly by Stabilizing the Cytoskeleton and Inhibiting Podocyte Apoptosis. PLoS One 2015; 10:e0132724. [PMID: 26161538 PMCID: PMC4498640 DOI: 10.1371/journal.pone.0132724] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2015] [Accepted: 06/17/2015] [Indexed: 01/11/2023] Open
Abstract
Objective Several studies have reported that tacrolimus (TAC) significantly reduced proteinuria in lupus nephritis (LN) patients and mouse models. However, the mechanism for this effect remains undetermined. This study explored the mechanism of how TAC protects podocytes from injury to identify new targets for protecting renal function. Methods MRL/lpr mice were given TAC at a dosage of 0.1 mg/kg per day by intragastric administration for 8 weeks. Urine and blood samples were collected. Kidney sections (2μm) were stained with hematoxylin-eosin (HE), periodic acid-Schiff base (PAS) and Masson's trichrome stain. Mouse podocyte cells (MPC5) were treated with TAC and/or TGF-β1 for 48h. The mRNA levels and protein expression of synaptopodin and Wilms’ tumor 1 (WT1) were determined by real-time PCR, Western blotting and/or immunofluorescence, respectively. Flow cytometry was used to detect cell apoptosis with annexin V. Podocyte foot processes were observed under transmission electron microscopy. IgG and C3 deposition were assessed with immunofluorescence assays and confocal microscopy. Results Synaptopodin expression significantly decreased in MRL/lpr disease control mice, accompanied by increases in 24-h proteinuria, blood urea nitrogen, and serum creatinine. TAC, however, reduced proteinuria, improved renal function, attenuated renal pathology, restored synaptopodin expression and preserved podocyte numbers. In MPC5 cells, TGF-β1 enhanced F-actin damage in podocytes and TAC stabilized it. TAC also decreased TGF-β1-induced podocyte apoptosis in vitro and inhibited foot process fusion in MRL/lpr mice. In addition, our results also showed TAC inhibited glomerular deposition of IgG and C3. Conclusion This study demonstrated that TAC reduced proteinuria and preserved renal function in LN through protecting podocytes from injury partly by stabilizing podocyte actin cytoskeleton and inhibiting podocyte apoptosis.
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Affiliation(s)
- Ruyi Liao
- Department of Nephrology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Nephrology, Guangzhou, China
- Key Laboratory of Nephrology, Ministry of Health, Guangzhou, China
| | - Qinghua Liu
- Department of Nephrology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Nephrology, Guangzhou, China
- Key Laboratory of Nephrology, Ministry of Health, Guangzhou, China
| | - Zhihua Zheng
- Department of Nephrology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Nephrology, Guangzhou, China
- Key Laboratory of Nephrology, Ministry of Health, Guangzhou, China
| | - Jinjin Fan
- Department of Nephrology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Nephrology, Guangzhou, China
- Key Laboratory of Nephrology, Ministry of Health, Guangzhou, China
| | - Wenxing Peng
- Department of Nephrology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Nephrology, Guangzhou, China
- Key Laboratory of Nephrology, Ministry of Health, Guangzhou, China
| | - Qingyu Kong
- Department of Nephrology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Nephrology, Guangzhou, China
- Key Laboratory of Nephrology, Ministry of Health, Guangzhou, China
| | - Huijuan He
- Department of Nephrology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Nephrology, Guangzhou, China
- Key Laboratory of Nephrology, Ministry of Health, Guangzhou, China
| | - Shicong Yang
- Department of Pathology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Wenfang Chen
- Department of Pathology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Xueqing Tang
- Department of Nephrology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Nephrology, Guangzhou, China
- Key Laboratory of Nephrology, Ministry of Health, Guangzhou, China
| | - Xueqing Yu
- Department of Nephrology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Nephrology, Guangzhou, China
- Key Laboratory of Nephrology, Ministry of Health, Guangzhou, China
- * E-mail:
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Abstract
Since the first demonstration of Nox enzyme expression in the kidney in the early 1990s and the subsequent identification of Nox4, or RENOX, a decade later, it has become apparent that the Nox family of reactive oxygen species (ROS) generating enzymes plays an integral role in the normal physiological function of the kidney. As our knowledge of Nox expression patterns and functions in various structures and specialized cell types within the kidney grows, so does the realization that Nox-derived oxidative stress contributes significantly to a wide variety of renal pathologies through their ability to modify lipids and proteins, damage DNA and activate transcriptional programmes. Diverse studies demonstrate key roles for Nox-derived ROS in kidney fibrosis, particularly in settings of chronic renal disease such as diabetic nephropathy. As the most abundant Nox family member in the kidney, much emphasis has been placed on the role of Nox4 in this setting. However, an ever growing body of work continues to uncover key roles for other Nox family members, not only in diabetic kidney disease, but in a diverse array of renal pathological conditions. The objective of the present review is to highlight the latest novel developments in renal Nox biology with an emphasis not only on diabetic nephropathy but many of the other renal disease contexts where oxidative stress is implicated.
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Lee SY, Kim SI, Choi ME. Therapeutic targets for treating fibrotic kidney diseases. Transl Res 2015; 165:512-30. [PMID: 25176603 PMCID: PMC4326607 DOI: 10.1016/j.trsl.2014.07.010] [Citation(s) in RCA: 132] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Revised: 07/24/2014] [Accepted: 07/28/2014] [Indexed: 12/11/2022]
Abstract
Renal fibrosis is the hallmark of virtually all progressive kidney diseases and strongly correlates with the deterioration of kidney function. The renin-angiotensin-aldosterone system blockade is central to the current treatment of patients with chronic kidney disease (CKD) for the renoprotective effects aimed to prevent or slow progression to end-stage renal disease (ESRD). However, the incidence of CKD is still increasing, and there is a critical need for new therapeutics. Here, we review novel strategies targeting various components implicated in the fibrogenic pathway to inhibit or retard the loss of kidney function. We focus, in particular, on antifibrotic approaches that target transforming growth factor (TGF)-β1, a key mediator of kidney fibrosis, and exciting new data on the role of autophagy. Bone morphogenetic protein (BMP)-7 and connective tissue growth factor (CTGF) are highlighted as modulators of profibrotic TGF-β activity. BMP-7 has a protective role against TGF-β1 in kidney fibrosis, whereas CTGF enhances TGF-β-mediated fibrosis. We also discuss recent advances in the development of additional strategies for antifibrotic therapy. These include strategies targeting chemokine pathways via CC chemokine receptors 1 and 2 to modulate the inflammatory response, inhibition of phosphodiesterase to restore nitric oxide-cyclic 3',5'-guanosine monophosphate function, inhibition of nicotinamide adenine dinucleotide phosphate oxidase 1 and 4 to suppress reactive oxygen species production, and inhibition of endothelin 1 or tumor necrosis factor α to ameliorate progressive renal fibrosis. Furthermore, a brief overview of some of the biomarkers of kidney fibrosis is currently being explored that may improve the ability to monitor antifibrotic therapies. It is hoped that evidence based on the preclinical and clinical data discussed in this review leads to novel antifibrotic therapies effective in patients with CKD to prevent or delay progression to ESRD.
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Affiliation(s)
- So-Young Lee
- Renal Division, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Mass; Department of Internal Medicine, Bundang CHA Medical Center, CHA University School of Medicine, Seongnam, South Korea
| | - Sung I Kim
- Division of Nephrology and Hypertension, Joan and Sanford I. Weill Department of Medicine, Weill Cornell Medical College, New York, NY
| | - Mary E Choi
- Renal Division, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Mass; Division of Nephrology and Hypertension, Joan and Sanford I. Weill Department of Medicine, Weill Cornell Medical College, New York, NY.
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Gorin Y, Wauquier F. Upstream regulators and downstream effectors of NADPH oxidases as novel therapeutic targets for diabetic kidney disease. Mol Cells 2015; 38:285-96. [PMID: 25824546 PMCID: PMC4400302 DOI: 10.14348/molcells.2015.0010] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Accepted: 01/12/2015] [Indexed: 02/07/2023] Open
Abstract
Oxidative stress has been linked to the pathogenesis of diabetic nephropathy, the complication of diabetes in the kidney. NADPH oxidases of the Nox family, and in particular the homologue Nox4, are a major source of reactive oxygen species in the diabetic kidney and are critical mediators of redox signaling in glomerular and tubulointerstitial cells exposed to the diabetic milieu. Here, we present an overview of the current knowledge related to the understanding of the role of Nox enzymes in the processes that control mesangial cell, podocyte and tubulointerstitial cell injury induced by hyperglycemia and other predominant factors enhanced in the diabetic milieu, including the renin-angiotensin system and transforming growth factor-β. The nature of the upstream modulators of Nox enzymes as well as the downstream targets of the Nox NADPH oxidases implicated in the propagation of the redox processes that alter renal biology in diabetes will be highlighted.
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Affiliation(s)
- Yves Gorin
- Department of Medicine, University of Texas Health Science Center, San Antonio, Texas,
USA
| | - Fabien Wauquier
- Department of Medicine, University of Texas Health Science Center, San Antonio, Texas,
USA
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Kong L, Wu H, Zhou W, Luo M, Tan Y, Miao L, Cai L. Sirtuin 1: A Target for Kidney Diseases. Mol Med 2015; 21:87-97. [PMID: 25587857 DOI: 10.2119/molmed.2014.00211] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Accepted: 01/12/2015] [Indexed: 12/21/2022] Open
Abstract
Sirtuin 1 (SIRT1) is an evolutionarily conserved NAD(+)-dependent histone deacetylase that is necessary for caloric restriction-related lifespan extension. SIRT1, as an intracellular energy sensor, detects the concentration of intracellular NAD(+) and uses this information to adapt cellular energy output to cellular energy requirements. Previous studies on SIRT1 have confirmed its beneficial effects on cellular immunity to oxidative stress, reduction of fibrosis, suppression of inflammation, inhibition of apoptosis, regulation of metabolism, induction of autophagy and regulation of blood pressure. All of the above biological processes are involved in the pathogenesis of kidney diseases. Therefore, the activation of SIRT1 may become a therapeutic target to improve the clinical outcome of kidney diseases. In this review, we give an overview of SIRT1 and its molecular targets as well as SIRT1-modulated biological processes, with a particular focus on the role of SIRT1 in kidney diseases.
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Affiliation(s)
- Lili Kong
- Department of Nephrology, the Second Hospital of Jilin University, Changchun, China.,Kosair Children's Hospital Research Institute, Department of Pediatrics, University of Louisville, Louisville, Kentucky
| | - Hao Wu
- Department of Nephrology, the Second Hospital of Jilin University, Changchun, China.,Kosair Children's Hospital Research Institute, Department of Pediatrics, University of Louisville, Louisville, Kentucky
| | - Wenhua Zhou
- Department of Nephrology, the Second Hospital of Jilin University, Changchun, China
| | - Manyu Luo
- Department of Nephrology, the Second Hospital of Jilin University, Changchun, China.,Kosair Children's Hospital Research Institute, Department of Pediatrics, University of Louisville, Louisville, Kentucky
| | - Yi Tan
- Kosair Children's Hospital Research Institute, Department of Pediatrics, University of Louisville, Louisville, Kentucky.,Department of Pharmacology and Toxicology, University of Louisville, Louisville, Kentucky
| | - Lining Miao
- Department of Nephrology, the Second Hospital of Jilin University, Changchun, China
| | - Lu Cai
- Kosair Children's Hospital Research Institute, Department of Pediatrics, University of Louisville, Louisville, Kentucky.,Department of Pharmacology and Toxicology, University of Louisville, Louisville, Kentucky
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Xie GB, Liu WJ, Pan ZJ, Cheng TY, Luo C. Evolution of the Mir-155 Family and Possible Targets in Cancers and the Immune System. Asian Pac J Cancer Prev 2014; 15:7547-52. [DOI: 10.7314/apjcp.2014.15.18.7547] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Smad3/Nox4-mediated mitochondrial dysfunction plays a crucial role in puromycin aminonucleoside-induced podocyte damage. Cell Signal 2014; 26:2979-91. [PMID: 25229402 DOI: 10.1016/j.cellsig.2014.08.030] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Accepted: 08/17/2014] [Indexed: 11/20/2022]
Abstract
Podocyte depletion due to apoptosis is the key hallmark of proteinuric kidney disease progression. Recently, several studies reported that mitochondrial (mt) dysfunction is involved in podocyte injury, while the underlying molecular mechanisms remain elusive. This study investigated the potential proximal signaling related to in vitro and in vivo mitochondrial dysfunction in a puromycin aminonucleoside (PA)-induced podocyte injury model. PA time- and dose-dependently resulted in cultured mouse podocyte damage, presenting with an increase of apoptotic cells and induction of activated caspase3/9. PA also caused mitochondrial damage and dysfunction based on the downregulation of the mtDNA level, decrease of transcriptional factors mtTfa and Nrf-1, decrease of CoxI, II and IV, and reduction of the oxygen consumption level and mitochondrial membrane potential level as well as excessive production of cellular ROS. Additionally, antioxidant MnSOD and catalase levels were decreased in mitochondrial fractions, and reduction of complex I and IV activity was also observed in PA-stimulated podocytes. Furthermore, an obvious translocation of p-Smad3 from the cytosol to nuclei and induction of mitochondrial Nox4 were detected following PA application. The PA-induced shift of cytochrome c was observed from mitochondria to the cytoplasm. Induction of Nox4 by PA administration was significantly repressed by Smad3-shRNA, while Nox4-shRNA showed no effect on PA-induced p-Smad3 activation. Notably, both Smad3 and Nox4 silencing significantly prevented the reduction of the mtDNA level, restored mitochondrial function, and decreased cellular apoptosis in PA-stimulated podocytes. A similar mitochondrial dysfunction was obtained in a PA-injected nephropathy rat, which was effectively inhibited by treatment with the antiproteinuric drug prednisone. In addition, Dab2 knockdown decreased albumin uptake and influx whereas it showed no effect on cellular apoptosis in PA-stimulated podocytes. In conclusion, our findings demonstrated that Smad3-Nox4 axis-mediated mitochondrial dysfunction is involved in PA-induced podocyte damage likely via increasing ROS generation and activating the cytochrome c-caspase9-caspase3 apoptotic signaling pathway. Dab2 may be required for the increased permeability of podocytes following injury.
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Chen J, Chen JK, Harris RC. EGF receptor deletion in podocytes attenuates diabetic nephropathy. J Am Soc Nephrol 2014; 26:1115-25. [PMID: 25185988 DOI: 10.1681/asn.2014020192] [Citation(s) in RCA: 98] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Accepted: 07/30/2014] [Indexed: 11/03/2022] Open
Abstract
The generation of reactive oxygen species (ROS), particularly superoxide, by damaged or dysfunctional mitochondria has been postulated to be an initiating event in the development of diabetes complications. The glomerulus is a primary site of diabetic injury, and podocyte injury is a classic hallmark of diabetic glomerular lesions. In streptozotocin-induced type 1 diabetes, podocyte-specific EGF receptor (EGFR) knockout mice (EGFR(podKO)) and their wild-type (WT) littermates had similar levels of hyperglycemia and polyuria, but EGFR(podKO) mice had significantly less albuminuria and less podocyte loss compared with WT diabetic mice. Furthermore, EGFR(podKO) diabetic mice had less TGF-β1 expression, Smad2/3 phosphorylation, and glomerular fibronectin deposition. Immunoblotting of isolated glomerular lysates revealed that the upregulation of cleaved caspase 3 and downregulation of Bcl2 in WT diabetic mice were attenuated in EGFR(podKO) diabetic mice. Administration of the SOD mimetic mito-tempol or the NADPH oxidase inhibitor apocynin attenuated the upregulation of p-c-Src, p-EGFR, p-ERK1/2, p-Smad2/3, and TGF-β1 expression and prevented the alteration of cleaved caspase 3 and Bcl2 expression in glomeruli of WT diabetic mice. High-glucose treatment of cultured mouse podocytes induced similar alterations in the production of ROS; phosphorylation of c-Src, EGFR, and Smad2/3; and expression of TGF-β1, cleaved caspase 3, and Bcl2. These alterations were inhibited by treatment with mito-tempol or apocynin or by inhibiting EGFR expression or activity. Thus, results of our studies utilizing mice with podocyte-specific EGFR deletion demonstrate that EGFR activation has a major role in activating pathways that mediate podocyte injury and loss in diabetic nephropathy.
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Affiliation(s)
- Jianchun Chen
- Department of Veterans Affairs, Nashville, Tennessee; Departments of Medicine and
| | - Jian-Kang Chen
- Departments of Cellular Biology and Anatomy and Medicine, Medical College of Georgia, Georgia Regents University, Augusta, Georgia
| | - Raymond C Harris
- Department of Veterans Affairs, Nashville, Tennessee; Departments of Medicine and Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee; and
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Terashima H, Kato M, Ebisawa M, Kobayashi H, Suzuki K, Nezu Y, Sada T. R-268712, an orally active transforming growth factor-β type I receptor inhibitor, prevents glomerular sclerosis in a Thy1 nephritis model. Eur J Pharmacol 2014; 734:60-6. [DOI: 10.1016/j.ejphar.2014.03.045] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2013] [Revised: 03/19/2014] [Accepted: 03/24/2014] [Indexed: 12/14/2022]
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Anil Kumar P, Welsh GI, Saleem MA, Menon RK. Molecular and cellular events mediating glomerular podocyte dysfunction and depletion in diabetes mellitus. Front Endocrinol (Lausanne) 2014; 5:151. [PMID: 25309512 PMCID: PMC4174857 DOI: 10.3389/fendo.2014.00151] [Citation(s) in RCA: 107] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Accepted: 09/10/2014] [Indexed: 12/11/2022] Open
Abstract
The essential function of the kidney is to ensure formation of a relatively protein-free ultra-filtrate, urine. The rate of filtration and composition of the primary renal filtrate is determined by the transport of fluid and solutes across the glomerular filtration barrier consisting of endothelial cells, the glomerular basement membrane, and podocyte foot processes. In diabetes mellitus (DM), components of the kidney that enable renal filtration get structurally altered and functionally compromised resulting in proteinuria that often progresses to end-stage renal disease. Histological alterations in DM include early hypertrophy of glomerular and tubular components, subsequent thickening of basement membrane in glomeruli and tubules, progressive accumulation of extracellular matrix proteins in the glomerular mesangium and loss of podocytes, together constituting a clinical condition referred to as diabetic nephropathy (DN). The glomerulus has become the focus of research investigating the mechanism of proteinuria. In particular, the progressive dysfunction and/or loss of podocytes that is contemporaneous with proteinuria in DN have attracted intense scientific attention. The absolute number of podocytes predicts glomerular function and podocyte injury is a hallmark of various glomerular diseases. This review discusses the importance of podocytes in normal renal filtration and details the molecular and cellular events that lead to podocyte dysfunction and decreased podocyte count in DN.
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Affiliation(s)
- P. Anil Kumar
- Department of Biochemistry, University of Hyderabad, Hyderabad, India
| | - Gavin I. Welsh
- Academic Renal Unit, School of Clinical Sciences, University of Bristol, Bristol, UK
| | - Moin A. Saleem
- Academic Renal Unit, School of Clinical Sciences, University of Bristol, Bristol, UK
| | - Ram K. Menon
- Pediatric Endocrinology and Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, USA
- *Correspondence: Ram K. Menon, University of Michigan Medical School, D1205 MPB/SPC 5718, 1500 E. Medical Center Drive, Ann Arbor, MI 48109-5718, USA e-mail:
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Müller-Deile J, Schiffer M. The podocyte power-plant disaster and its contribution to glomerulopathy. Front Endocrinol (Lausanne) 2014; 5:209. [PMID: 25566185 PMCID: PMC4266017 DOI: 10.3389/fendo.2014.00209] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2014] [Accepted: 11/21/2014] [Indexed: 11/22/2022] Open
Abstract
Proper podocyte function within the glomerulus demands a high and continuous energy supply that is mainly derived from the respiratory chain of the inner mitochondrial membrane. Dysregulations in the metabolic homeostasis of podocytes may result in podocyte damage and glomerular disease. This article highlights the current knowledge about podocyte energy supply by the respiratory chain. We review the regulation of mitochondrial oxidative metabolism with regard to podocytopathy and discuss the latest understanding of different mitochondrial dysfunctions of the podocyte in diabetic nephropathy and focal segmental glomerulosclerosis (FSGS). We discuss genetic forms of mitochondriopathy of the podocyte and end with recent knowledge about crosstalk between NADH and NADPH and potential therapeutic options for podocyte mitochondriopathy. We aim to raise awareness for the complex and interesting mechanisms of podocyte damage by impaired energy supply that, despite of novel findings in recent years, is poorly understood so far.
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Affiliation(s)
- Janina Müller-Deile
- Division of Nephrology and Hypertension, Department of Medicine, Hannover Medical School, Hannover, Germany
| | - Mario Schiffer
- Division of Nephrology and Hypertension, Department of Medicine, Hannover Medical School, Hannover, Germany
- *Correspondence: Mario Schiffer, Division of Nephrology, Hannover Medical School, Carl-Neuberg-Str. 1, Hannover 30625, Germany e-mail:
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