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Haley KE, Kronenberg NM, Liehm P, Elshani M, Bell C, Harrison DJ, Gather MC, Reynolds PA. Podocyte injury elicits loss and recovery of cellular forces. SCIENCE ADVANCES 2018; 4:eaap8030. [PMID: 29963620 PMCID: PMC6021140 DOI: 10.1126/sciadv.aap8030] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Accepted: 05/22/2018] [Indexed: 06/08/2023]
Abstract
In the healthy kidney, specialized cells called podocytes form a sophisticated blood filtration apparatus that allows excretion of wastes and excess fluid from the blood while preventing loss of proteins such as albumin. To operate effectively, this filter is under substantial hydrostatic mechanical pressure. Given their function, it is expected that the ability to apply mechanical force is crucial to the survival of podocytes. However, to date, podocyte mechanobiology remains poorly understood, largely because of a lack of experimental data on the forces involved. We perform quantitative, continuous, nondisruptive, and high-resolution measurements of the forces exerted by differentiated podocytes in real time using a recently introduced functional imaging modality for continuous force mapping. Using an accepted model for podocyte injury, we find that injured podocytes experience near-complete loss of cellular force transmission but that this loss of force is reversible under certain conditions. The observed changes in force correlate with F-actin rearrangement and reduced expression of podocyte-specific proteins. By introducing robust and high-throughput mechanical phenotyping and by demonstrating the significance of mechanical forces in podocyte injury, this research paves the way to a new level of understanding of the kidney. In addition, in an advance over established force mapping techniques, we integrate cellular force measurements with immunofluorescence and perform continuous long-term force measurements of a cell population. Hence, our approach has general applicability to a wide range of biomedical questions involving mechanical forces.
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Affiliation(s)
- Kathryn E. Haley
- School of Medicine, University of St Andrews, St Andrews KY16 9TF, UK
- Biomedical Sciences Research Complex, University of St Andrews, St Andrews, UK
| | - Nils M. Kronenberg
- Biomedical Sciences Research Complex, University of St Andrews, St Andrews, UK
- Scottish Universities Physics Alliance, School of Physics & Astronomy, University of St Andrews, St Andrews KY16 9SS, UK
| | - Philipp Liehm
- Biomedical Sciences Research Complex, University of St Andrews, St Andrews, UK
- Scottish Universities Physics Alliance, School of Physics & Astronomy, University of St Andrews, St Andrews KY16 9SS, UK
| | - Mustafa Elshani
- School of Medicine, University of St Andrews, St Andrews KY16 9TF, UK
- Biomedical Sciences Research Complex, University of St Andrews, St Andrews, UK
| | - Cameron Bell
- School of Medicine, University of St Andrews, St Andrews KY16 9TF, UK
| | - David J. Harrison
- School of Medicine, University of St Andrews, St Andrews KY16 9TF, UK
- Biomedical Sciences Research Complex, University of St Andrews, St Andrews, UK
| | - Malte C. Gather
- Biomedical Sciences Research Complex, University of St Andrews, St Andrews, UK
- Scottish Universities Physics Alliance, School of Physics & Astronomy, University of St Andrews, St Andrews KY16 9SS, UK
| | - Paul A. Reynolds
- School of Medicine, University of St Andrews, St Andrews KY16 9TF, UK
- Biomedical Sciences Research Complex, University of St Andrews, St Andrews, UK
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Hallow KM, Gebremichael Y. A Quantitative Systems Physiology Model of Renal Function and Blood Pressure Regulation: Application in Salt-Sensitive Hypertension. CPT-PHARMACOMETRICS & SYSTEMS PHARMACOLOGY 2017; 6:393-400. [PMID: 28556624 PMCID: PMC5488119 DOI: 10.1002/psp4.12177] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Revised: 01/05/2017] [Accepted: 01/23/2017] [Indexed: 01/13/2023]
Abstract
Salt‐sensitivity (SS) refers to changes in blood pressure in response to changes in sodium intake. SS individuals are at greater risk for developing kidney disease, and also respond differently to antihypertensive therapies compared to salt‐resistant (SR) individuals. In this study we used a systems pharmacology model of renal function (presented in a companion article) to evaluate the ability of proposed mechanisms to produce salt‐sensitivity. The model reproduced previously published data on renal functional changes in response to salt‐intake, and also predicted that glomerular pressure, a variable that is not easily evaluated clinically but is a key factor in renal injury, increases with salt intake in SS hypertension. We then used the model to generate mechanistic insight into the differential blood pressure and glomerular pressure responses to angiotensin converting enzyme (ACE) inhibitors, thiazide diuretics, and calcium channel blockers observed in SS and SR hypertension.
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Affiliation(s)
- K M Hallow
- University of Georgia, Athens, Georgia, USA
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Zhang L, Li K, Yan X, Liang X, Wang S, Han Q, Zhao RC. MicroRNA-498 Inhibition Enhances the Differentiation of Human Adipose-Derived Mesenchymal Stem Cells into Podocyte-Like Cells. Stem Cells Dev 2015; 24:2841-52. [DOI: 10.1089/scd.2015.0027] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Affiliation(s)
- Lina Zhang
- Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing, People's Republic of China
| | - Kanghua Li
- Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing, People's Republic of China
| | - Xi Yan
- Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing, People's Republic of China
| | - Xiaolei Liang
- Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing, People's Republic of China
| | - Shihua Wang
- Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing, People's Republic of China
| | - Qin Han
- Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing, People's Republic of China
| | - Robert Chunhua Zhao
- Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing, People's Republic of China
- Peking Union Medical College Hospital, Beijing, People's Republic of China
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Li Y, Shen Y, Li M, Su D, Xu W, Liang X, Li R. Inhibitory effects of peroxisome proliferator-activated receptor γ agonists on collagen IV production in podocytes. Mol Cell Biochem 2015; 405:233-41. [PMID: 25920446 DOI: 10.1007/s11010-015-2414-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2015] [Accepted: 04/18/2015] [Indexed: 12/14/2022]
Abstract
Peroxisome proliferator-activated receptor-γ (PPAR-γ) agonists have beneficial effects on the kidney diseases through preventing microalbuminuria and glomerulosclerosis. However, the mechanisms underlying these effects remain to be fully understood. In this study, we investigate the effects of PPAR-γ agonist, rosiglitazone (Rosi) and pioglitazone (Pio), on collagen IV production in mouse podocytes. The endogenous expression of PPAR-γ was found in the primary podocytes and can be upregulated by Rosi and Pio, respectively, detected by RT-PCR and Western blot. PPAR-γ agonist markedly blunted the increasing of collagen IV expression and extraction in podocytes induced by TGF-β. In contrast, adding PPAR-γ antagonist, GW9662, to podocytes largely prevented the inhibition of collagen IV expression from Pio treatment. Our data also showed that phosphorylation of Smad2/3 enhanced by TGF-β in a time-dependent manner was significantly attenuated by adding Pio. The promoter region of collagen IV gene contains one putative consensus sequence of Smad-binding element (SBE) by promoter analysis, Rosi and Pio significantly ameliorated TGF-β-induced SBE4-luciferase activity. In conclusion, PPAR-γ activation by its agonist, Rosi or Pio, in vitro directly inhibits collagen IV expression and synthesis in primary mouse podocytes. The suppression of collagen IV production was related to the inhibition of TGF-β-driven phosphorylation of Smad2/3 and decreased response activity of SBEs of collagen IV in PPAR-γ agonist-treated mouse podocytes. This represents a novel mechanistic support regarding PPAR-γ agonists as podocyte protective agents.
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Affiliation(s)
- Yanjiao Li
- Department of Nephrology, Shanxi Provincial People's Hospital, The Affiliated People's Hospital of Shanxi Medical University, Taiyuan, 030012, Shanxi, China
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Hou G, Wu V, Singh G, Holzman LB, Tsui CC. Ret is critical for podocyte survival following glomerular injury in vivo. Am J Physiol Renal Physiol 2015; 308:F774-83. [PMID: 25587123 DOI: 10.1152/ajprenal.00483.2014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Accepted: 01/06/2015] [Indexed: 12/16/2022] Open
Abstract
Podocyte injury and loss directly cause proteinuria and the progression to glomerulosclerosis. Elucidation of the mechanisms of podocyte survival and recovery from injury is critical for designing strategies to prevent the progression of glomerular diseases. Glial cell line-derived neurotrophic factor (GDNF) and its receptor tyrosine kinase, Ret, are upregulated in both nonimmune and immune-mediated in vitro and in vivo models of glomerular diseases. We investigated whether Ret, a known receptor tyrosine kinase critical for kidney morphogenesis and neuronal growth and development, is necessary for glomerular and podocyte development and survival in vivo. Since deletions of both GDNF and Ret result in embryonic lethality due to kidney agenesis, we examined the role of Ret in vivo by generating mice with a conditional deletion of Ret in podocytes (Ret(flox/flox); Nphs2-Cre). In contrast to the lack of any developmental and maintenance deficits, Ret(flox/flox); Nphs2-Cre mice showed a significantly enhanced susceptibility to adriamycin nephropathy, a rodent model of focal segmental glomerulosclerosis. Thus, these findings demonstrated that the Ret signaling pathway is important for podocyte survival and recovery from glomerular injury in vivo.
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Affiliation(s)
- Guoqing Hou
- Division of Nephrology, Department of Internal Medicine, University of Michigan School of Medicine, Ann Arbor, Michigan; and
| | - Victoria Wu
- Division of Nephrology, Department of Internal Medicine, University of Michigan School of Medicine, Ann Arbor, Michigan; and
| | - Gulmohar Singh
- Division of Nephrology, Department of Internal Medicine, University of Michigan School of Medicine, Ann Arbor, Michigan; and
| | - Lawrence B Holzman
- Division of Renal Electrolyte and Hypertension, Department of Internal Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
| | - Cynthia C Tsui
- Division of Nephrology, Department of Internal Medicine, University of Michigan School of Medicine, Ann Arbor, Michigan; and
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Kriz W, Lemley KV. A potential role for mechanical forces in the detachment of podocytes and the progression of CKD. J Am Soc Nephrol 2014; 26:258-69. [PMID: 25060060 DOI: 10.1681/asn.2014030278] [Citation(s) in RCA: 187] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Loss of podocytes underlies progression of CKD. Detachment of podocytes from the glomerular basement membrane (GBM) rather than apoptosis or necrosis seems to be the major mechanism of podocyte loss. Such detachment of viable podocytes may be caused by increased mechanical distending and shear forces and/or impaired adhesion to the GBM. This review considers the mechanical challenges that may lead to podocyte loss by detachment from the GBM under physiologic and pathophysiologic conditions, including glomerular hypertension, hyperfiltration, hypertrophy, and outflow of filtrate from subpodocyte spaces. Furthermore, we detail the cellular mechanisms by which podocytes respond to these challenges, discuss the protective effects of angiotensin blockade, and note the questions that must be addressed to better understand the relationship between podocyte detachment and progression of CKD.
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Affiliation(s)
- Wilhelm Kriz
- Institutes of Transfusion Medicine and Immunology and Neuroanatomy, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany; and
| | - Kevin V Lemley
- Division of Nephrology, Children's Hospital Los Angeles, Los Angeles, California; and Department of Pediatrics, University of Southern California Keck School of Medicine, Los Angeles, California
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Carlson EC, Chhoun JM, Laturnus DI, Bikash KC, Berg B, Zheng S, Epstein PN. Podocyte-specific overexpression of metallothionein mitigates diabetic complications in the glomerular filtration barrier and glomerular histoarchitecture: a transmission electron microscopy stereometric analysis. Diabetes Metab Res Rev 2013; 29:113-24. [PMID: 22926941 DOI: 10.1002/dmrr.2342] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2011] [Revised: 05/03/2012] [Accepted: 08/01/2012] [Indexed: 01/26/2023]
Abstract
BACKGROUND We previously demonstrated that cellular and extracellular components of the blood-urine barrier in renal glomeruli are susceptible to damage in OVE transgenic mice, a valuable model of human diabetic nephropathy that expresses profound albuminuria. METHODS To test our hypothesis that glomerular filtration barrier damage in OVE mice may be the result of oxidative insult to podocytes, 150-day-old bi-transgenic OVENmt diabetic mice that overexpress the antioxidant metallothionein specifically in podocytes were examined by enzyme-linked immunosorbent assay for albuminuria mitigation and by unbiased transmission electron microscopy (TEM) stereometry for protection from chronic structural diabetic complications. RESULTS Although blood glucose and HbA(1c) levels were indistinguishable in OVE and OVENmt animals, albuminuria was significantly reduced (average >7-fold) in OVENmt mice through 8 months of age. Interestingly, the Nmt transgene provided significant glomerular protection against diabetic nephropathic complications outside of the podocyte. Glomerular filtration barrier damage was reduced in OVENmt mice, including significantly increased area occupied by endothelial luminal fenestrations (~13%), significantly reduced glomerular basement membrane (GBM) thickening (~17%) and significantly less podocyte effacement (~18%). In addition, OVENmt mice exhibited significantly reduced glomerular volume (~50%), fewer glomerular endothelial cells (~33%), fewer mesangial cells (~57%) and fewer total glomerular cells (~40%). CONCLUSIONS These results provide evidence of oxidative damage to podocytes induces primary diabetic nephropathic features including severe and sustained albuminuria, specific glomerular filtration barrier damage and alterations in glomerular endothelial and mesangial cell number. Importantly, these diabetic complications are significantly mitigated by podocyte targeted metallothionein overexpression.
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Affiliation(s)
- Edward C Carlson
- Department of Anatomy and Cell Biology, University of North Dakota, Grand Forks, ND 58202, USA.
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Wang G, Lai FMM, Lai KB, Chow KM, Kwan BCH, Li KTP, Szeto CC. Intra-renal and urinary mRNA expression of podocyte-associated molecules for the estimation of glomerular podocyte loss. Ren Fail 2010; 32:372-9. [DOI: 10.3109/08860221003611737] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Teiken JM, Audettey JL, Laturnus DI, Zheng S, Epstein PN, Carlson EC. Podocyte loss in aging OVE26 diabetic mice. Anat Rec (Hoboken) 2008; 291:114-21. [PMID: 18085629 DOI: 10.1002/ar.20625] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Recent studies show that podocyte nuclear density (N(V)) and numbers of renal podocytes per glomerulus (N) are altered in experimental and spontaneous diabetes mellitus. N(V) and N are generally reduced, and it has been hypothesized that these morphological changes may relate to the loss of glomerular permselectivity in diabetic nephropathy (DN). In the current study, OVE26 transgenic diabetic mice and age-matched (FVB) controls (60, 150, or 450 days) were fixed by vascular perfusion and renal cortical tissues were prepared for morphometric analyses. ImageJ software and point counting analyses were carried out on light and transmission electron micrographs to determine glomerular volume (V(G)), N(V), and N. As expected, mean V(G) in OVE26 mice increased substantially ( approximately 134%) over the course of the study and was significantly increased over FVB mice at all ages. At 60 days, N(V) and N were not statistically distinguishable in OVE26 and control mice, while at 150 days, N(V) was significantly reduced in diabetics but not N. In 450-day-old OVE26 animals, however, N(V) and N were both significantly decreased ( approximately 231% and approximately 99%, respectively) relative to age-matched FVB mice. These data suggest that in the OVE26 model of diabetes, significant podocyte loss occurs relatively late in the course of the disease. Moreover, it seems possible that these podocytic changes could play a role in sustaining the increased permeability of the blood-urine barrier in the later stages of diabetic renal decompensation.
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Affiliation(s)
- Jennifer M Teiken
- Department of Anatomy and Cell Biology, University of North Dakota, Grand Forks, North Dakota, USA
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Wang G, Lai FMM, Lai KB, Chow KM, Li KTP, Szeto CC. Messenger RNA expression of podocyte-associated molecules in the urinary sediment of patients with diabetic nephropathy. Nephron Clin Pract 2007; 106:c169-79. [PMID: 17596726 DOI: 10.1159/000104428] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2006] [Accepted: 03/08/2007] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Podocyte loss plays an important role in the pathogenesis of diabetic nephropathy. We hypothesize that messenger RNA expression of podocyte-associated molecules in urinary sediment may provide important clinical information in patients with diabetic nephropathy. METHOD We studied 21 patients with biopsy-proven diabetic nephropathy and 9 healthy controls. The mRNA expression of nephrin, podocin, synaptopodin, Wilms' tumor-1 (WT-1) and alpha-actinin-4 in urinary sediment were measured by real-time quantitative polymerase chain reaction. The degree of histological damage was quantified by morphometric analysis. Patients were then followed for an average of 25.63 +/- 10.76 months. The rate of glomerular filtration rate (GFR) decline was calculated by the least-square regression. RESULTS There were significant differences in nephrin, podocin, synaptopodin, alpha-actinin-4 (p < 0.01 for all comparisons) and WT-1 (p = 0.028) expression between patients and normal controls. Urinary nephrin expression was significantly correlated with proteinuria (r = 0.502, p = 0.020); urinary synaptopodin was significantly correlated with proteinuria (r = 0.585, p = 0.005), serum creatinine (r = 0.516, p = 0.017) and estimated GFR (r = -0.560, p = 0.008), and urinary WT-1 expression was significantly correlated with the degree of tubulointerstitial fibrosis (r = 0.558, p = 0.009). There was no significant correlation between GFR decline and urinary expression of target genes. CONCLUSION Urinary mRNA expressions of nephrin, podocin, synaptopodin, WT-1 and alpha-actinin-4 are higher in patients with diabetic nephropathy than in normal controls. Urinary nephrin and synaptopodin expressions are correlated with baseline clinical parameters such as proteinuria or renal function, while WT-1 expression is related to the degree of histological damage. Our results suggest that urinary mRNA expression of podocyte-associated molecules may be used for risk stratification of diabetic nephropathy.
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Affiliation(s)
- Gang Wang
- Department of Medicine and Therapeutics, Prince of Wales Hospital, Chinese University of Hong Kong, Hong Kong, SAR, China
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Dandapani SV, Sugimoto H, Matthews BD, Kolb RJ, Sinha S, Gerszten RE, Zhou J, Ingber DE, Kalluri R, Pollak MR. α-Actinin-4 Is Required for Normal Podocyte Adhesion. J Biol Chem 2007; 282:467-77. [PMID: 17082197 DOI: 10.1074/jbc.m605024200] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mutations in the alpha-actinin-4 gene ACTN4 cause an autosomal dominant human kidney disease. Mice deficient in alpha-actinin-4 develop a recessive phenotype characterized by kidney failure, proteinuria, glomerulosclerosis, and retraction of glomerular podocyte foot processes. However, the mechanism by which alpha-actinin-4 deficiency leads to glomerular disease has not been defined. Here, we examined the effect of alpha-actinin-4 deficiency on the adhesive properties of podocytes in vivo and in a cell culture system. In alpha-actinin-4-deficient mice, we observed a decrease in the number of podocytes per glomerulus compared with wild-type mice as well as the presence of podocyte markers in the urine. Podocyte cell lines generated from alpha-actinin-4-deficient mice were less adherent than wild-type cells to glomerular basement membrane (GBM) components collagen IV and laminin 10 and 11. We also observed markedly reduced adhesion of alpha-actinin-4-deficient podocytes under increasing shear stresses. This adhesion deficit was restored by transfecting cells with alpha-actinin-4-GFP. We tested the strength of the integrin receptor-mediated linkages to the cytoskeleton by applying force to microbeads bound to integrin using magnetic pulling cytometry. Beads bound to alpha-actinin-4-deficient podocytes showed greater displacement in response to an applied force than those bound to wild-type cells. Consistent with integrin-dependent alpha-actinin-4-mediated adhesion, phosphorylation of beta1-integrins on alpha-actinin-4-deficient podocytes is reduced. We rescued the phosphorylation deficit by transfecting alpha-actinin-4 into alpha-actinin-4-deficient podocytes. These results suggest that alpha-actinin-4 interacts with integrins and strengthens the podocyte-GBM interaction thereby stabilizing glomerular architecture and preventing disease.
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Affiliation(s)
- Savita V Dandapani
- Department of Genetics, Harvard Medical School, Boston, Massachusetts, USA
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Petermann AT, Pippin J, Krofft R, Blonski M, Griffin S, Durvasula R, Shankland SJ. Viable podocytes detach in experimental diabetic nephropathy: potential mechanism underlying glomerulosclerosis. Nephron Clin Pract 2005; 98:e114-23. [PMID: 15627794 DOI: 10.1159/000081555] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2004] [Accepted: 06/06/2004] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND A decrease in podocyte number contributes to the development of glomerulosclerosis in diabetic nephropathy. Although podocytes have been detected in the urine in certain glomerular diseases, their viability is poorly understood. METHODS Diabetes was induced in rats with streptozotocin. Urine was collected from control rats (given citrate), and rats with diabetic nephropathy, and cells obtained by centrifugation were resuspended in tissue culture media, and seeded onto collagen-coated tissue culture plates. Cells were grown under standard cell culture conditions ex vivo. Cell number was measured, the cell type in the urine was identified by immunostaining with specific antibodies, and morphology was assessed by light and electron microscopy. RESULTS Within 24 h, cells obtained from the urine of diabetic rats attached to tissue culture plates ex vivo. Cells were not detected in the urine from control rats. All cells from diabetic rats stained positive for the podocyte-specific proteins synaptopodin, nephrin, podocin and Glepp-1 and negative for mesangial (OX-7), tubular (Tamm-Horsfall protein) and endothelial (RECA) cell antigens. The cell number increased daily, which is consistent with cell growth ex vivo. CONCLUSIONS Rats with diabetic nephropathy shed podocytes into the urine that attach and grow ex vivo. These results are consistent with the detachment of viable podocytes in diabetes and add new perspectives into our understanding of development of glomerulosclerosis in diabetes mellitus.
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Affiliation(s)
- Arndt T Petermann
- Department of Medicine, Division of Nephrology, University of Washington School of Medicine, Seattle, Wash 98195, USA
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