1
|
Huang W, Liu H, Zhu S, Woodson M, Liu R, Tilton RG, Miller JD, Zhang W. Sirt6 deficiency results in progression of glomerular injury in the kidney. Aging (Albany NY) 2017; 9:1069-1083. [PMID: 28351995 PMCID: PMC5391219 DOI: 10.18632/aging.101214] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2016] [Accepted: 03/18/2017] [Indexed: 02/06/2023]
Abstract
Aging is associated with an increased incidence and prevalence of renal glomerular diseases. Sirtuin (Sirt) 6, a nicotinamide adenine dinucleotide (NAD)-dependent histone deacetylase, has been shown to protect against multiple age-associated phenotypes; however it is unknown whether Sirt6 has a direct pathophysiologic role in the kidney. In the present study, we demonstrate that Sirt6 is expressed in the kidney and aging Sirt6-deficient mice exhibit renal hypertrophy with glomerular enlargement. Sirt6 deletion induces podocyte injury, including decreases in slit diaphragm proteins, foot process effacement, and cellular loss, resulting in proteinuria. Knockdown of Sirt6 in cultured primary murine podocytes induces shape changes with loss of process formation and cell apoptosis. Moreover, Sirt6 deficiency results in progressive renal inflammation and fibrosis. Collectively, these data provide compelling evidence that Sirt6 is important for podocyte homeostasis and maintenance of glomerular function, and warrant further investigation into the role of Sirt6 in age-associated kidney dysfunction.
Collapse
Affiliation(s)
- Wen Huang
- Department of Healthcare, Qianfoshan Hospital Affiliated to Shandong University, Jinan, China.,Department of Ophthalmology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Hua Liu
- Center for Biomedical Engineering, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Shuang Zhu
- Department of Ophthalmology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Michael Woodson
- Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Rong Liu
- Department of Ophthalmology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Ronald G Tilton
- Department of Internal Medicine, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Jordan D Miller
- Department of Surgery, Mayo Clinic, Rochester, MN 55905, USA
| | - Wenbo Zhang
- Department of Ophthalmology, University of Texas Medical Branch, Galveston, TX 77555, USA.,Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, TX 77555, USA
| |
Collapse
|
2
|
Ito Y, Hsu MF, Bettaieb A, Koike S, Mello A, Calvo-Rubio M, Villalba JM, Haj FG. Protein tyrosine phosphatase 1B deficiency in podocytes mitigates hyperglycemia-induced renal injury. Metabolism 2017; 76:56-69. [PMID: 28987240 PMCID: PMC5690491 DOI: 10.1016/j.metabol.2017.07.009] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Revised: 07/13/2017] [Accepted: 07/31/2017] [Indexed: 01/13/2023]
Abstract
OBJECTIVE Diabetic nephropathy is one of the most devastating complications of diabetes, and growing evidence implicates podocyte dysfunction in disease pathogenesis. The objective of this study was to investigate the contribution of protein tyrosine phosphatase 1B (PTP1B) in podocytes to hyperglycemia-induced renal injury. METHODS To determine the in vivo function of PTP1B in podocytes we generated mice with podocyte-specific PTP1B disruption (hereafter termed pod-PTP1B KO). Kidney functions were determined in control and pod-PTP1B KO mice under normoglycemia and high-fat diet (HFD)- and streptozotocin (STZ)-induced hyperglycemia. RESULTS PTP1B expression increased in murine kidneys following HFD and STZ challenges. Under normoglycemia control and pod-PTP1B KO mice exhibited comparable renal functions. However, podocyte PTP1B disruption attenuated hyperglycemia-induced albuminuria and renal injury and preserved glucose control. Also, podocyte PTP1B disruption was accompanied with improved renal insulin signaling and enhanced autophagy with decreased inflammation and fibrosis. Moreover, the beneficial effects of podocyte PTP1B disruption in vivo were recapitulated in E11 murine podocytes with lentiviral-mediated PTP1B knockdown. Reconstitution of PTP1B in knockdown podocytes reversed the enhanced insulin signaling and autophagy suggesting that they were likely a consequence of PTP1B deficiency. Further, pharmacological attenuation of autophagy in PTP1B knockdown podocytes mitigated the protective effects of PTP1B deficiency. CONCLUSIONS These findings demonstrate that podocyte PTP1B deficiency attenuates hyperglycemia-induced renal damage and suggest that PTP1B may present a therapeutic target in renal injury.
Collapse
Affiliation(s)
- Yoshihiro Ito
- Department of Nutrition, University of California Davis, One Shields Ave, Davis, CA 95616, United States
| | - Ming-Fo Hsu
- Department of Nutrition, University of California Davis, One Shields Ave, Davis, CA 95616, United States
| | - Ahmed Bettaieb
- Department of Nutrition, University of California Davis, One Shields Ave, Davis, CA 95616, United States
| | - Shinichiro Koike
- Department of Nutrition, University of California Davis, One Shields Ave, Davis, CA 95616, United States
| | - Aline Mello
- Department of Nutrition, University of California Davis, One Shields Ave, Davis, CA 95616, United States
| | - Miguel Calvo-Rubio
- Department of Cell Biology, Physiology and Immunology, Agrifood Campus of International Excellence ceiA3, University of Cordoba, 14014 Cordoba, Spain
| | - Jose M Villalba
- Department of Cell Biology, Physiology and Immunology, Agrifood Campus of International Excellence ceiA3, University of Cordoba, 14014 Cordoba, Spain
| | - Fawaz G Haj
- Department of Nutrition, University of California Davis, One Shields Ave, Davis, CA 95616, United States; Comprehensive Cancer Center, University of California Davis, Sacramento, CA 95817, United States; Division of Endocrinology, Diabetes, and Metabolism, Department of Internal Medicine, University of California Davis, Sacramento, CA 95817, United States.
| |
Collapse
|
3
|
Alexanian A, Sorokin A. Cyclooxygenase 2: protein-protein interactions and posttranslational modifications. Physiol Genomics 2017; 49:667-681. [PMID: 28939645 DOI: 10.1152/physiolgenomics.00086.2017] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Numerous studies implicate the cyclooxygenase 2 (COX2) enzyme and COX2-derived prostanoids in various human diseases, and thus, much effort has been made to uncover the regulatory mechanisms of this enzyme. COX2 has been shown to be regulated at both the transcriptional and posttranscriptional levels, leading to the development of nonsteroidal anti-inflammatory drugs (NSAIDs) and selective COX2 inhibitors (COXIBs), which inhibit the COX2 enzyme through direct targeting. Recently, evidence of posttranslational regulation of COX2 enzymatic activity by s-nitrosylation, glycosylation, and phosphorylation has also been presented. Additionally, posttranslational regulators that actively downregulate COX2 expression by facilitating increased proteasome degradation of this enzyme have also been reported. Moreover, recent data identified proteins, located in close proximity to COX2 enzyme, that serve as posttranslational modulators of COX2 function, upregulating its enzymatic activity. While the precise mechanisms of the protein-protein interaction between COX2 and these regulatory proteins still need to be addressed, it is likely these interactions could regulate COX2 activity either as a result of conformational changes of the enzyme or by impacting subcellular localization of COX2 and thus affecting its interactions with regulatory proteins, which further modulate its activity. It is possible that posttranslational regulation of COX2 enzyme by such proteins could contribute to manifestation of different diseases. The uncovering of posttranslational regulation of COX2 enzyme will promote the development of more efficient therapeutic strategies of indirectly targeting the COX2 enzyme, as well as provide the basis for the generation of novel diagnostic tools as biomarkers of disease.
Collapse
Affiliation(s)
- Anna Alexanian
- Cardiovascular Center and Department of Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Andrey Sorokin
- Cardiovascular Center and Department of Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin
| |
Collapse
|
4
|
Martínez-García C, Izquierdo-Lahuerta A, Vivas Y, Velasco I, Yeo TK, Chen S, Medina-Gomez G. Renal Lipotoxicity-Associated Inflammation and Insulin Resistance Affects Actin Cytoskeleton Organization in Podocytes. PLoS One 2015; 10:e0142291. [PMID: 26545114 PMCID: PMC4636358 DOI: 10.1371/journal.pone.0142291] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Accepted: 10/19/2015] [Indexed: 01/01/2023] Open
Abstract
In the last few decades a change in lifestyle has led to an alarming increase in the prevalence of obesity and obesity-associated complications. Obese patients are at increased risk of developing hypertension, heart disease, insulin resistance (IR), dyslipidemia, type 2 diabetes and renal disease. The excess calories are stored as triglycerides in adipose tissue, but also may accumulate ectopically in other organs, including the kidney, which contributes to the damage through a toxic process named lipotoxicity. Recently, the evidence suggests that renal lipid accumulation leads to glomerular damage and, more specifically, produces dysfunction in podocytes, key cells that compose and maintain the glomerular filtration barrier. Our aim was to analyze the early mechanisms underlying the development of renal disease associated with the process of lipotoxicity in podocytes. Our results show that treatment of podocytes with palmitic acid produced intracellular accumulation of lipid droplets and abnormal glucose and lipid metabolism. This was accompanied by the development of inflammation, oxidative stress and endoplasmic reticulum stress and insulin resistance. We found specific rearrangements of the actin cytoskeleton and slit diaphragm proteins (Nephrin, P-Cadherin, Vimentin) associated with this insulin resistance in palmitic-treated podocytes. We conclude that lipotoxicity accelerates glomerular disease through lipid accumulation and inflammation. Moreover, saturated fatty acids specifically promote insulin resistance by disturbing the cytoarchitecture of podocytes. These data suggest that renal lipid metabolism and cytoskeleton rearrangements may serve as a target for specific therapies aimed at slowing the progression of podocyte failure during metabolic syndrome.
Collapse
Affiliation(s)
- Cristina Martínez-García
- Departamento de Ciencias Básicas de la Salud, Área de Bioquímica y Genética Molecular. Universidad Rey Juan Carlos, Avda. de Atenas s/n, Alcorcón, Madrid, Spain
| | - Adriana Izquierdo-Lahuerta
- Departamento de Ciencias Básicas de la Salud, Área de Bioquímica y Genética Molecular. Universidad Rey Juan Carlos, Avda. de Atenas s/n, Alcorcón, Madrid, Spain
| | - Yurena Vivas
- Departamento de Ciencias Básicas de la Salud, Área de Bioquímica y Genética Molecular. Universidad Rey Juan Carlos, Avda. de Atenas s/n, Alcorcón, Madrid, Spain
| | - Ismael Velasco
- Departamento de Ciencias Básicas de la Salud, Área de Bioquímica y Genética Molecular. Universidad Rey Juan Carlos, Avda. de Atenas s/n, Alcorcón, Madrid, Spain
| | - Tet-Kin Yeo
- Division of Nephrology/Hypertension, Northwestern University, Chicago, Illinois, United States of America
| | - Sheldon Chen
- Division of Nephrology/Hypertension, Northwestern University, Chicago, Illinois, United States of America
| | - Gema Medina-Gomez
- Departamento de Ciencias Básicas de la Salud, Área de Bioquímica y Genética Molecular. Universidad Rey Juan Carlos, Avda. de Atenas s/n, Alcorcón, Madrid, Spain
| |
Collapse
|
5
|
Kistler AD, Singh G, Altintas MM, Yu H, Fernandez IC, Gu C, Wilson C, Srivastava SK, Dietrich A, Walz K, Kerjaschki D, Ruiz P, Dryer S, Sever S, Dinda AK, Faul C, Reiser J. Transient receptor potential channel 6 (TRPC6) protects podocytes during complement-mediated glomerular disease. J Biol Chem 2013; 288:36598-609. [PMID: 24194522 DOI: 10.1074/jbc.m113.488122] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Gain-of-function mutations in the calcium channel TRPC6 lead to autosomal dominant focal segmental glomerulosclerosis and podocyte expression of TRPC6 is increased in some acquired human glomerular diseases, particularly in membranous nephropathy. These observations led to the hypothesis that TRPC6 overactivation is deleterious to podocytes through pathological calcium signaling, both in genetic and acquired diseases. Here, we show that the effects of TRPC6 on podocyte function are context-dependent. Overexpression of TRPC6 alone did not directly affect podocyte morphology and cytoskeletal structure. Unexpectedly, however, overexpression of TRPC6 protected podocytes from complement-mediated injury, whereas genetic or pharmacological TRPC6 inactivation increased podocyte susceptibility to complement. Mechanistically, this effect was mediated by Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) activation. Podocyte-specific TRPC6 transgenic mice showed stronger CaMKII activation, reduced podocyte foot process effacement and reduced levels of proteinuria during nephrotoxic serum nephritis, whereas TRPC6 null mice exhibited reduced CaMKII activation and higher levels of proteinuria compared with wild type littermates. Human membranous nephropathy biopsy samples showed podocyte staining for active CaMKII, which correlated with the degree of TRPC6 expression. Together, these data suggest a dual and context dependent role of TRPC6 in podocytes where acute activation protects from complement-mediated damage, but chronic overactivation leads to focal segmental glomerulosclerosis.
Collapse
Affiliation(s)
- Andreas D Kistler
- From the Division of Nephrology and Hypertension, Department of Medicine, University of Miami Miller School of Medicine, Miami, Florida 33136
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
6
|
Hale LJ, Welsh GI, Perks CM, Hurcombe JA, Moore S, Hers I, Saleem MA, Mathieson PW, Murphy AJ, Jeansson M, Holly JM, Hardouin SN, Coward RJ. Insulin-like growth factor-II is produced by, signals to and is an important survival factor for the mature podocyte in man and mouse. J Pathol 2013; 230:95-106. [PMID: 23299523 DOI: 10.1002/path.4165] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2012] [Revised: 12/03/2012] [Accepted: 12/26/2012] [Indexed: 01/10/2023]
Abstract
Podocytes are crucial for preventing the passage of albumin into the urine and, when lost, are associated with the development of albuminuria, renal failure and cardiovascular disease. Podocytes have limited capacity to regenerate, therefore pro-survival mechanisms are critically important. Insulin-like growth factor-II (IGF-II) is a potent survival and growth factor; however, its major function is thought to be in prenatal development, when circulating levels are high. IGF-II has only previously been reported to continue to be expressed in discrete regions of the brain into adulthood in rodents, with systemic levels being undetectable. Using conditionally immortalized human and ex vivo adult mouse cells of the glomerulus, we demonstrated the podocyte to be the major glomerular source and target of IGF-II; it signals to this cell via the IGF-I receptor via the PI3 kinase and MAPK pathways. Functionally, a reduction in IGF signalling causes podocyte cell death in vitro and glomerular disease in vivo in an aged IGF-II transgenic mouse that produces approximately 60% of IGF-II due to a lack of the P2 promoter of this gene. Collectively, this work reveals the fundamental importance of IGF-II in the mature podocyte for glomerular health across mammalian species.
Collapse
Affiliation(s)
- L J Hale
- Academic and Children's Renal Unit, University of Bristol, Learning and Research, Southmead Hospital, Bristol, BS10 5NB, UK
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
7
|
Holme A, Hurcombe JA, Straatman-Iwanowska A, Inward CI, Gissen P, Coward RJ. Glomerular involvement in the arthrogryposis, renal dysfunction and cholestasis syndrome. Clin Kidney J 2013; 6:183-8. [PMID: 26019847 PMCID: PMC4432437 DOI: 10.1093/ckj/sfs182] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2012] [Accepted: 12/12/2012] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Arthrogryposis, renal dysfunction and cholestasis (ARC) syndrome is a multisystem autosomal-recessive disorder caused by defects in the VPS33B and VIPAR genes, involved in localization of apical membrane proteins. Affected children usually die by 1 year of age, often secondary to infective complications. The classic renal manifestation previously described in ARC syndrome is proximal-tubular dysfunction. The aim of this study is to gain further insight into the renal manifestations of this syndrome. METHODS Clinical review of three cases of ARC syndrome presenting to a tertiary centre. Together with measurement of VPS33B and VIPAR protein expression in the human glomerulus. RESULTS The cases demonstrated severe failure to thrive and in addition to commonly described features profound proteinuria and albuminuria, together with hypoalbuminaemia, suggesting glomerular involvement of this syndrome. Western blotting of conditionally immortalized human glomerular cells and ex vivo immunofluorescent analysis of the human glomerulus revealed that VPS33B and VIPAR were highly expressed in glomerular endothelium, and podocytes, but not in the mesangium. CONCLUSIONS ARC syndrome affects the glomerulus as well as the proximal tubule in the kidney. Our molecular studies suggest that both cell types that constitute the glomerular filtration barrier are affected in this condition, providing an explanation for the albuminuria that we have observed in our cases.
Collapse
Affiliation(s)
- Amelia Holme
- Department of Child and Adolescent Health , University of Bristol , Bristol , UK ; Department of Paediatric Nephrology , Bristol Royal Hospital for Children , Bristol , UK
| | | | | | - Carol I Inward
- Department of Paediatric Nephrology , Bristol Royal Hospital for Children , Bristol , UK
| | - Paul Gissen
- MRC Laboratory for Molecular Cell Biology , University College London , London , UK ; Department of Paediatric Metabolic Medicine , Great Ormond Street Hospital , London , UK
| | - Richard J Coward
- Department of Paediatric Nephrology , Bristol Royal Hospital for Children , Bristol , UK ; Academic Renal Unit , University of Bristol , Bristol , UK
| |
Collapse
|
8
|
Tang VW, Brieher WM. α-Actinin-4/FSGS1 is required for Arp2/3-dependent actin assembly at the adherens junction. ACTA ACUST UNITED AC 2012; 196:115-30. [PMID: 22232703 PMCID: PMC3255975 DOI: 10.1083/jcb.201103116] [Citation(s) in RCA: 138] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
We have developed an in vitro assay to study actin assembly at cadherin-enriched cell junctions. Using this assay, we demonstrate that cadherin-enriched junctions can polymerize new actin filaments but cannot capture preexisting filaments, suggesting a mechanism involving de novo synthesis. In agreement with this hypothesis, inhibition of Arp2/3-dependent nucleation abolished actin assembly at cell-cell junctions. Reconstitution biochemistry using the in vitro actin assembly assay identified α-actinin-4/focal segmental glomerulosclerosis 1 (FSGS1) as an essential factor. α-Actinin-4 specifically localized to sites of actin incorporation on purified membranes and at apical junctions in Madin-Darby canine kidney cells. Knockdown of α-actinin-4 decreased total junctional actin and inhibited actin assembly at the apical junction. Furthermore, a point mutation of α-actinin-4 (K255E) associated with FSGS failed to support actin assembly and acted as a dominant negative to disrupt actin dynamics at junctional complexes. These findings demonstrate that α-actinin-4 plays an important role in coupling actin nucleation to assembly at cadherin-based cell-cell adhesive contacts.
Collapse
Affiliation(s)
- Vivian W Tang
- Department of Cell and Developmental Biology, University of Illinois, Urbana, IL 61801, USA
| | | |
Collapse
|
9
|
Takiue K, Sugiyama H, Inoue T, Morinaga H, Kikumoto Y, Kitagawa M, Kitamura S, Maeshima Y, Wang DH, Masuoka N, Ogino K, Makino H. Acatalasemic mice are mildly susceptible to adriamycin nephropathy and exhibit increased albuminuria and glomerulosclerosis. BMC Nephrol 2012; 13:14. [PMID: 22443450 PMCID: PMC3329410 DOI: 10.1186/1471-2369-13-14] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2011] [Accepted: 03/25/2012] [Indexed: 11/30/2022] Open
Abstract
Background Catalase is an important antioxidant enzyme that regulates the level of intracellular hydrogen peroxide and hydroxyl radicals. The effects of catalase deficiency on albuminuria and progressive glomerulosclerosis have not yet been fully elucidated. The adriamycin (ADR) nephropathy model is considered to be an experimental model of focal segmental glomerulosclerosis. A functional catalase deficiency was hypothesized to exacerbate albuminuria and the progression of glomerulosclerosis in this model. Methods ADR was intravenously administered to both homozygous acatalasemic mutant mice (C3H/AnLCsbCsb) and control wild-type mice (C3H/AnLCsaCsa). The functional and morphological alterations of the kidneys, including albuminuria, renal function, podocytic, glomerular and tubulointerstitial injuries, and the activities of catalase were then compared between the two groups up to 8 weeks after disease induction. Moreover, the presence of a mutation of the toll-like receptor 4 (tlr4) gene, which was previously reported in the C3H/HeJ strain, was investigated in both groups. Results The ADR-treated mice developed significant albuminuria and glomerulosclerosis, and the degree of these conditions in the ADR-treated acatalasemic mice was higher than that in the wild-type mice. ADR induced progressive renal fibrosis, renal atrophy and lipid peroxide accumulation only in the acatalasemic mice. In addition, the level of catalase activity was significantly lower in the kidneys of the acatalasemic mice than in the wild-type mice during the experimental period. The catalase activity increased after ADR injection in wild-type mice, but the acatalasemic mice did not have the ability to increase their catalase activity under oxidative stress. The C3H/AnL strain was found to be negative for the tlr4 gene mutation. Conclusions These data indicate that catalase deficiency plays an important role in the progression of renal injury in the ADR nephropathy model.
Collapse
Affiliation(s)
- Keiichi Takiue
- Department of Medicine and Clinical Science, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1 Shikatacho, Kita-ku, Okayama 700-8558, Japan
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
10
|
Gbadegesin R, Lavin P, Foreman J, Winn M. Pathogenesis and therapy of focal segmental glomerulosclerosis: an update. Pediatr Nephrol 2011; 26:1001-15. [PMID: 21110043 PMCID: PMC3624015 DOI: 10.1007/s00467-010-1692-x] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/25/2010] [Revised: 09/28/2010] [Accepted: 10/04/2010] [Indexed: 02/07/2023]
Abstract
Focal and segmental glomerulosclerosis (FSGS) is an important cause of steroid-resistant nephrotic syndrome in adults and children. It is responsible for 5-20% of all cases of end-stage kidney disease (ESKD) in the United States. The pathogenesis of FSGS has not been fully elucidated; however, data from molecular studies of familial cases in the last two decades suggest that FSGS is a defect of the podocyte. The therapeutic agents available for treatment of FSGS are not very effective and only a small percentage of affected individuals will achieve complete remission. Recent data from molecular biology and molecular genetics has provided insight into the mechanisms of action of old agents and also identification of other novel therapeutic targets. This review focuses on recent advances in the molecular pathogenesis of FSGS and currently available therapeutic agents as well as potential novel therapies.
Collapse
Affiliation(s)
- Rasheed Gbadegesin
- Department of Pediatrics, Duke University Medical Center, Durham, NC 27710, USA.
| | | | | | | |
Collapse
|
11
|
Eckel J, Lavin PJ, Finch EA, Mukerji N, Burch J, Gbadegesin R, Wu G, Bowling B, Byrd A, Hall G, Sparks M, Zhang ZS, Homstad A, Barisoni L, Birbaumer L, Rosenberg P, Winn MP. TRPC6 enhances angiotensin II-induced albuminuria. J Am Soc Nephrol 2011; 22:526-35. [PMID: 21258036 DOI: 10.1681/asn.2010050522] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Mutations in the canonical transient receptor potential cation channel 6 (TRPC6) are responsible for familial forms of adult onset focal segmental glomerulosclerosis (FSGS). The mechanisms by which TRPC6 mutations cause kidney disease are not well understood. We used TRPC6-deficient mice to examine the function of TRPC6 in the kidney. We found that adult TRPC6-deficient mice had BP and albumin excretion rates similar to wild-type animals. Glomerular histomorphology revealed no abnormalities on both light and electron microscopy. To determine whether the absence of TRPC6 would alter susceptibility to hypertension and renal injury, we infused mice with angiotensin II continuously for 28 days. Although both groups developed similar levels of hypertension, TRPC6-deficient mice had significantly less albuminuria, especially during the early phase of the infusion; this suggested that TRPC6 adversely influences the glomerular filter. We used whole-cell patch-clamp recording to measure cell-membrane currents in primary cultures of podocytes from both wild-type and TRPC6-deficient mice. In podocytes from wild-type mice, angiotensin II and a direct activator of TRPC6 both augmented cell-membrane currents; TRPC6 deficiency abrogated these increases in current magnitude. Our findings suggest that TRPC6 promotes albuminuria, perhaps by promoting angiotensin II-dependent increases in Ca(2+), suggesting that TRPC6 blockade may be therapeutically beneficial in proteinuric kidney disease.
Collapse
Affiliation(s)
- Jason Eckel
- Center for Human Genetics, Duke University Medical Center, Durham, NC 27710, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
12
|
Welsh GI, Hale LJ, Eremina V, Jeansson M, Maezawa Y, Lennon R, Pons DA, Owen RJ, Satchell SC, Miles MJ, Caunt CJ, McArdle CA, Pavenstädt H, Tavaré JM, Herzenberg AM, Kahn CR, Mathieson PW, Quaggin SE, Saleem MA, Coward RJM. Insulin signaling to the glomerular podocyte is critical for normal kidney function. Cell Metab 2010; 12:329-340. [PMID: 20889126 PMCID: PMC4949331 DOI: 10.1016/j.cmet.2010.08.015] [Citation(s) in RCA: 329] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2010] [Revised: 05/21/2010] [Accepted: 07/07/2010] [Indexed: 12/21/2022]
Abstract
Diabetic nephropathy (DN) is the leading cause of renal failure in the world. It is characterized by albuminuria and abnormal glomerular function and is considered a hyperglycemic "microvascular" complication of diabetes, implying a primary defect in the endothelium. However, we have previously shown that human podocytes have robust responses to insulin. To determine whether insulin signaling in podocytes affects glomerular function in vivo, we generated mice with specific deletion of the insulin receptor from their podocytes. These animals develop significant albuminuria together with histological features that recapitulate DN, but in a normoglycemic environment. Examination of "normal" insulin-responsive podocytes in vivo and in vitro demonstrates that insulin signals through the MAPK and PI3K pathways via the insulin receptor and directly remodels the actin cytoskeleton of this cell. Collectively, this work reveals the critical importance of podocyte insulin sensitivity for kidney function.
Collapse
Affiliation(s)
- Gavin I Welsh
- Academic Renal Unit, School of Clinical Sciences, University of Bristol, Bristol BS8 1TH, UK
| | - Lorna J Hale
- Academic Renal Unit, School of Clinical Sciences, University of Bristol, Bristol BS8 1TH, UK
| | - Vera Eremina
- Samuel Lunenfeld Research Institute, Mount Sinai Hospital, University of Toronto, Toronto, Ontario M5G 1X5, Canada
| | - Marie Jeansson
- Samuel Lunenfeld Research Institute, Mount Sinai Hospital, University of Toronto, Toronto, Ontario M5G 1X5, Canada
| | - Yoshiro Maezawa
- Samuel Lunenfeld Research Institute, Mount Sinai Hospital, University of Toronto, Toronto, Ontario M5G 1X5, Canada
| | - Rachel Lennon
- Academic Renal Unit, School of Clinical Sciences, University of Bristol, Bristol BS8 1TH, UK
| | - Deborah A Pons
- Academic Renal Unit, School of Clinical Sciences, University of Bristol, Bristol BS8 1TH, UK
| | - Rachel J Owen
- School of Physics, School of Clinical Sciences, University of Bristol, Bristol BS8 1TH, UK
| | - Simon C Satchell
- Academic Renal Unit, School of Clinical Sciences, University of Bristol, Bristol BS8 1TH, UK
| | - Mervyn J Miles
- School of Physics, School of Clinical Sciences, University of Bristol, Bristol BS8 1TH, UK
| | - Christopher J Caunt
- Department of Molecular Pharmacology, School of Clinical Sciences, University of Bristol, Bristol BS8 1TH, UK
| | - Craig A McArdle
- Department of Molecular Pharmacology, School of Clinical Sciences, University of Bristol, Bristol BS8 1TH, UK
| | - Hermann Pavenstädt
- Department of Internal Medicine D, Nephrology and Hypertension, University Clinics Muenster, Muenster 48149, Germany
| | - Jeremy M Tavaré
- School of Biochemistry, School of Clinical Sciences, University of Bristol, Bristol BS8 1TH, UK
| | - Andrew M Herzenberg
- Department of Pathology, University Health Network and University of Toronto, Ontario M5G 2C4, Canada
| | - C Ronald Kahn
- Joslin Diabetes Center and Harvard Medical School, Boston, MA 02215, USA
| | - Peter W Mathieson
- Academic Renal Unit, School of Clinical Sciences, University of Bristol, Bristol BS8 1TH, UK
| | - Susan E Quaggin
- Samuel Lunenfeld Research Institute, Mount Sinai Hospital, University of Toronto, Toronto, Ontario M5G 1X5, Canada
| | - Moin A Saleem
- Academic Renal Unit, School of Clinical Sciences, University of Bristol, Bristol BS8 1TH, UK
| | - Richard J M Coward
- Academic Renal Unit, School of Clinical Sciences, University of Bristol, Bristol BS8 1TH, UK; Samuel Lunenfeld Research Institute, Mount Sinai Hospital, University of Toronto, Toronto, Ontario M5G 1X5, Canada.
| |
Collapse
|
13
|
|
14
|
|
15
|
Rienstra H, Katta K, Celie JWAM, van Goor H, Navis G, van den Born J, Hillebrands JL. Differential expression of proteoglycans in tissue remodeling and lymphangiogenesis after experimental renal transplantation in rats. PLoS One 2010; 5:e9095. [PMID: 20140097 PMCID: PMC2816722 DOI: 10.1371/journal.pone.0009095] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2009] [Accepted: 01/04/2010] [Indexed: 12/31/2022] Open
Abstract
Background Chronic transplant dysfunction explains the majority of late renal allograft loss and is accompanied by extensive tissue remodeling leading to transplant vasculopathy, glomerulosclerosis and interstitial fibrosis. Matrix proteoglycans mediate cell-cell and cell-matrix interactions and play key roles in tissue remodeling. The aim of this study was to characterize differential heparan sulfate proteoglycan and chondroitin sulfate proteoglycan expression in transplant vasculopathy, glomerulosclerosis and interstitial fibrosis in renal allografts with chronic transplant dysfunction. Methods Renal allografts were transplanted in the Dark Agouti-to-Wistar Furth rat strain combination. Dark Agouti-to-Dark Agouti isografts and non-transplanted Dark Agouti kidneys served as controls. Allograft and isograft recipients were sacrificed 66 and 81 days (mean) after transplantation, respectively. Heparan sulfate proteoglycan (collXVIII, perlecan and agrin) and chondroitin sulfate proteoglycan (versican) expression, as well as CD31 and LYVE-1 (vascular and lymphatic endothelium, respectively) expression were (semi-) quantitatively analyzed using immunofluorescence. Findings Arteries with transplant vasculopathy and sclerotic glomeruli in allografts displayed pronounced neo-expression of collXVIII and perlecan. In contrast, in interstitial fibrosis expression of the chondroitin sulfate proteoglycan versican dominated. In the cortical tubular basement membranes in both iso- and allografts, induction of collXVIII was detected. Allografts presented extensive lymphangiogenesis (p<0.01 compared to isografts and non-transplanted controls), which was associated with induced perlecan expression underneath the lymphatic endothelium (p<0.05 and p<0.01 compared to isografts and non-transplanted controls, respectively). Both the magnitude of lymphangiogenesis and perlecan expression correlated with severity of interstitial fibrosis and impaired graft function. Interpretation Our results reveal that changes in the extent of expression and the type of proteoglycans being expressed are tightly associated with tissue remodeling after renal transplantation. Therefore, proteoglycans might be potential targets for clinical intervention in renal chronic transplant dysfunction.
Collapse
Affiliation(s)
- Heleen Rienstra
- Immunology Section, Department of Cell Biology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Kirankumar Katta
- Nephrology Division, Department of Internal Medicine, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Johanna W. A. M. Celie
- Department of Pathology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Harry van Goor
- Pathology Division, Department of Pathology & Medical Biology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Gerjan Navis
- Nephrology Division, Department of Internal Medicine, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Jacob van den Born
- Nephrology Division, Department of Internal Medicine, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Jan-Luuk Hillebrands
- Pathology Division, Department of Pathology & Medical Biology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
- * E-mail:
| |
Collapse
|