16
views
0
recommends
+1 Recommend
0 collections
    0
    shares
      • Record: found
      • Abstract: found
      • Article: found
      Is Open Access

      Upregulation ofα3β1-Integrin in Podocytes in Early-Stage Diabetic Nephropathy

      Journal of Diabetes Research
      Hindawi Limited

      Read this article at

          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

          Abstract

          Background. Podocyte injury plays an important role in the onset and progression of diabetic nephropathy (DN). Downregulation ofα3β1-integrin expression in podocytes is thought to be associated with podocyte detachment from the glomerular basement membrane, although the mechanisms remain obscure. To determine the mechanism of podocyte detachment, we analyzed the expression levels ofα3β1-integrin in podocytes in early and advanced stages of DN.Methods. Surgical specimens from DN patients were examined byin situhybridization, and the expression levels ofα3- andβ1-integrin subunits in glomeruli of early ( n = 6 ) and advanced ( n = 8 ) stages were compared with those of normal glomeruli ( n = 5 ). Heat-sensitive mouse podocytes (HSMP) were cultured with TGF-β1 to reproduce the microenvironment of glomeruli of DN, and the expression levels of integrin subunits and the properties of migration and attachment were examined.Results. Podocytes of early-stage DN showed upregulation ofα3- andβ1-integrin expression while those of advanced stage showed downregulation. Real-time PCR indicated a tendency for upregulation ofα3- andβ1-integrin in HSMP cultured with TGF-β1. TGF-β1-stimulated HSMP also showed enhancedin vitromigration and attachment on collagen substrate.Conclusions. The results suggested that podocyte detachment during early stage of DN is mediated through upregulation ofα3β1-integrin.

          Related collections

          Most cited references40

          • Record: found
          • Abstract: found
          • Article: not found

          From the periphery of the glomerular capillary wall toward the center of disease: podocyte injury comes of age in diabetic nephropathy.

          Nephropathy is a major complication of diabetes. Alterations of mesangial cells have traditionally been the focus of research in deciphering molecular mechanisms of diabetic nephropathy. Injury of podocytes, if recognized at all, has been considered a late consequence caused by increasing proteinuria rather than an event inciting diabetic nephropathy. However, recent biopsy studies in humans have provided evidence that podocytes are functionally and structurally injured very early in the natural history of diabetic nephropathy. The diabetic milieu, represented by hyperglycemia, nonenzymatically glycated proteins, and mechanical stress associated with hypertension, causes downregulation of nephrin, an important protein of the slit diaphragm with antiapoptotic signaling properties. The loss of nephrin leads to foot process effacement of podocytes and increased proteinuria. A key mediator of nephrin suppression is angiotensin II (ANG II), which can activate other cytokine pathways such as transforming growth factor-beta (TGF-beta) and vascular endothelial growth factor (VEGF) systems. TGF-beta1 causes an increase in mesangial matrix deposition and glomerular basement membrane (GBM) thickening and may promote podocyte apoptosis or detachment. As a result, the denuded GBM adheres to Bowman's capsule, initiating the development of glomerulosclerosis. VEGF is both produced by and acts upon the podocyte in an autocrine manner to modulate podocyte function, including the synthesis of GBM components. Through its effects on podocyte biology, glomerular hemodynamics, and capillary endothelial permeability, VEGF likely plays an important role in diabetic albuminuria. The mainstays of therapy, glycemic control and inhibition of ANG II, are key measures to prevent early podocyte injury and the subsequent development of diabetic nephropathy.
            Bookmark
            • Record: found
            • Abstract: found
            • Article: not found

            Natural inhibitor of transforming growth factor-beta protects against scarring in experimental kidney disease.

            The central pathological feature of human kidney disease that leads to kidney failure is the accumulation of extracellular matrix in glomeruli. Overexpression of transforming growth factor-beta (TGF-beta) underlies the accumulation of pathological matrix in experimental glomerulonephritis. Administration of an antibody raised against TGF-beta to glomerulonephritic rats suppresses glomerular matrix production and prevents matrix accumulation in the injured glomeruli. One of the matrix components induced by TGF-beta, the proteoglycan decorin, can bind TGF-beta and neutralize its biological activity, so decorin may be a natural regulator of TGF-beta (refs 3, 4). We tested whether decorin could antagonize the action of TGF-beta in vivo using the experimental glomerulonephritis model. We report here that administration of decorin inhibits the increased production of extracellular matrix and attenuates manifestations of disease, confirming our hypothesis. On the basis of our results, decorin may eventually prove to be clinically useful in diseases associated with overproduction of TGF-beta.
              Bookmark
              • Record: found
              • Abstract: found
              • Article: not found

              Podocyte detachment and reduced glomerular capillary endothelial fenestration in human type 1 diabetic nephropathy.

              The aim of this study was to investigate the structural characteristics of podocytes and endothelial cells in diabetic nephropathy. We studied 18 patients with type 1 diabetes (seven normoalbuminuric, six microalbuminuric, and five proteinuric), and six normal control subjects. Groups were not different for age. Type 1 diabetic groups were not different for diabetes duration or age at diabetes onset. Podocyte foot process width (FPW), fraction of glomerular basement membrane (GBM) surface with intact nondetached foot processes (IFP), fraction of glomerular capillary luminal surface covered by fenestrated endothelium [S(S)(Fenestrated/cap)] and classic diabetic glomerulopathy lesions were morphometrically measured. Albumin excretion (AER) and glomerular filtration (GFR) rates were also measured. GFR correlated inversely and AER directly with GBM and mesangial measurements in diabetic patients. FPW correlated inversely with GFR (r = -0.71, P = 0.001) and directly with AER (r = 0.66, P = 0.003), GBM, and mesangial parameters. The GBM fraction covered by IFP was decreased in proteinuric versus control subjects (P = 0.001), normoalbuminuric patients (P = 0.0002) and microalbuminuric patients (P = 0.04) and correlated with renal structural and functional parameters, including AER (r = -0.52, P = 0.03). Only 78% of GBM was covered by IFP in proteinuric patients. S(S)(Fenestrated/cap) was reduced in normoalbuminuric (P = 0.03), microalbuminuric (P = 0.03), and proteinuric (P = 0.002) patients versus control subjects. S(S)(Fenestrated/cap) correlated with mesangial fractional volume per glomerulus (r = -0.57, P = 0.01), IFP (r = 0.61, P = 0.007), and FPW (r = -0.58, P = 0.01). These novel studies document that podocyte detachment and diminished endothelial cell fenestration are related to classical diabetic nephropathy lesions and renal function in type 1 diabetic patients and support a need for further studies of podocyte/GBM adherence and podocyte/endothelial cell functional interactions in diabetic nephropathy.
                Bookmark

                Author and article information

                Journal
                10.1155/2016/9265074
                http://creativecommons.org/licenses/by/4.0/

                Comments

                Comment on this article