nephrin and Diabetes-Mellitus

Extra-capillary hypercellularity is a common finding in crescentic glomerulonephritis (GN) and focal segmental glomerulosclerosis (FSGS). In diabetic nephropathy (DN), extra-capillary hypercellularity is often observed as a finding of complications such as IgA nephropathy or microscopic polyangiitis superimposed on DN. However, in rare cases, epithelial cell proliferation may accompany DN. We experienced a case of nodular diabetic glomerulosclerosis with marked extra-capillary hypercellularity and revealed the origin of this atypical lesion using immunostainings.. A man in his 50 s was admitted to the hospital with nephrotic syndrome, and a renal biopsy was performed. Diffuse nodular lesions and extra-capillary hypercellularity were observed, but the results of serological examination or immunofluorescent assays did not implicate any other crescentic GN. Immunostaining for claudin-1 and nephrin was performed to identify the origin of the extra-capillary lesions. Given the clinical course and pathological findings, a diagnosis of DN-associated extra-capillary cell proliferation was made.. Extra-capillary hypercellularity, which resembles FSGS or crescentic GN, is a rare finding in DN and should therefore be treated with caution. In such cases, co-staining for claudin-1 and nephrin may facilitate the diagnosis of DN.

Topics: Cell Proliferation; Claudin-1; Diabetes Mellitus; Diabetic Nephropathies; Glomerulonephritis, IGA; Glomerulonephritis, Membranoproliferative; Glomerulosclerosis, Focal Segmental; Humans; Male; Membrane Proteins; Microscopic Polyangiitis; Middle Aged

Podocytes, the key component of the glomerular filtration barrier (GFB), are gradually lost during the progression of diabetic kidney disease (DKD), severely compromising kidney functionality. The molecular mechanisms regulating the survival of podocytes in DKD are incompletely understood. Here, we show that membrane-associated guanylate kinase inverted 2 (MAGI2) is specifically expressed in renal podocytes, and promotes podocyte survival in DKD. We found that MAGI2 expression was downregulated in podocytes cultured with high-glucose in vitro, and in kidneys of db/db mice as well as DKD patients. Conversely, we found enforced expression of MAGI2 via AAV transduction protected podocytes from apoptosis, with concomitant improvement of renal functions. Mechanistically, we found that MAGI2 deficiency induced by high glucose levels activates TGF-β signaling to decrease the expression of anti-apoptotic proteins. These results indicate that MAGI2 protects podocytes from cell death, and can be harnessed therapeutically to improve renal function in diabetic kidney disease.

Topics: Adaptor Proteins, Signal Transducing; Animals; Apoptosis; Communication; Diabetes Mellitus; Diabetic Nephropathies; Glucose; Guanylate Kinases; Humans; Mice; Podocytes; Transforming Growth Factor beta

Diabetes and hypertension have become the primary causes of chronic kidney disease worldwide. However, there are no established markers for early diagnosis or predicting renal prognosis. Here, we investigated the expression profiles of DNA repair and DNA methylation factors in human urine-derived cells as a possible diagnostic or renal prognosis-predicting marker. A total of 75 subjects, aged 63.3 ± 1.9 years old, were included in this study. DNA and RNA were extracted from 50 mL of urine samples. We evaluated DNA double-strand breaks (DSBs) by the quantitative long distance-PCR method and performed real-time RT-PCR analysis to analyze the expression of renal cell-specific markers, DNA DSB repair factor KAT5, DNA methyltransferases DNMTs, and demethylation enzymes TETs. In patients with hypertension and diabetes, DNA DSBs of the nephrin gene increased with decreased urine KAT5/nephrin expression, consistent with our previous study (Cell Rep 2019). In patients with hypertension, DNA DSBs of the AQP1 gene were increased with elevated urine DNMTs/AQP1 and TETs/AQP1 expression. Moreover, urine DNMTs/AQP1 expression was significantly correlated with the annual eGFR decline rate after adjustment for age, baseline eGFR, the presence of diabetes and the amount of albuminuria, suggesting a possible role as a renal prognosis predictor.

Topics: Adult; Aged; Aged, 80 and over; Aquaporin 1; Diabetes Mellitus; DNA (Cytosine-5-)-Methyltransferases; DNA Breaks, Double-Stranded; DNA Methylation; Female; Glomerular Filtration Rate; Humans; Hypertension; Logistic Models; Lysine Acetyltransferase 5; Male; Membrane Proteins; Middle Aged; Proto-Oncogene Proteins; Urine

EDA2R is a member of the large family of tumor necrosis factor receptor (TNFR). Previous studies suggested that EDA2R expression might be increased in the kidneys of diabetic mice. However, its mRNA and protein expression in kidneys were not analyzed; moreover, its role in the development of diabetic kidney disease was not explored. Here we analyzed the mRNA and protein expressions of EDA2R in diabetic kidneys and examined its role in the podocyte injury in high glucose milieu. By analysis with real-time PCR, Western blotting, we found that both the mRNA and protein levels of EDA2R were increased in the kidneys of diabetic mice. Immunohistochemical studies revealed that EDA2R expression was enhanced in both glomerular and tubular cells of diabetic mice and humans. In vitro studies, high glucose increased EDA2R expression in cultured human podocytes. Overexpression of EDA2R in podocytes promoted podocyte apoptosis and decreased nephrin expression. Moreover, ED2AR increased ROS generation in podocytes, while inhibiting ROS generation attenuates EDA2R-mediated podocyte injury. In addition, EDA2R silencing partially suppressed high glucose-induced ROS generation, apoptosis, and nephrin decrease. Our study demonstrated that high glucose increases EDA2R expression in kidney cells and that EDA2R induces podocyte apoptosis and dedifferentiation in high glucose milieu partially through enhanced ROS generation.

Topics: Animals; Apoptosis; Cells, Cultured; Diabetes Mellitus; Diabetic Nephropathies; Female; Kidney; Membrane Proteins; Mice; Podocytes; Reactive Oxygen Species; RNA, Messenger; Xedar Receptor

Hypertension-induced podocyte damage and the relationship with UAE is analyzed in diabetic and nondiabetic participants.. Sixty-four hypertensive patients, 30 diabetics, with glomerular filtration rate (eGFR) greater than 60 ml/min per 1.73 m were included. Urinary albumin excretion was measured in morning urine using a nephelometric immunoassay and expressed as albumin/creatinine ratio. Urinary pellets were obtained from fresh urine and mRNA was assessed by real-time quantitative PCR. Likewise, protein podocyte-specific molecules were measured by western blot using specific antibodies.. Fourteen nondiabetics and 20 diabetics had increased UAE greater than 30 mg/g. In individuals with increased EUA, the mRNA expression of nephrin and CD2AP was low in diabetics, whereas only nephrin mRNA in nondiabetics. No differences were observed in podocalyxin and aquaporin-1 mRNA levels. Concerning the protein values, in both nondiabetic and diabetic patients, nephrin, CD2AP and podocalyxin were increased in patients with increased UAE, with no differences in aquaporin-1. A significant positive relationship was observed between log UAE and nephrin protein values, and an inverse association observed with mRNA.. Hypertensive patients who had elevated UAE showed increased urinary excretion of podocyte-specific proteins coupled with a phenotype of decreased mRNA expression. The phenotype of podocyte-specific mRNA and the increment of nephrin can be used as a valuable marker of early glomerular injury.

Topics: Adaptor Proteins, Signal Transducing; Adult; Aged; Albuminuria; Aquaporin 1; Cytoskeletal Proteins; Diabetes Mellitus; Female; Humans; Hypertension; Kidney Diseases; Male; Membrane Proteins; Middle Aged; Podocytes; RNA, Messenger; Sialoglycoproteins

Nephrin is a core component of podocyte (glomerular epithelial cell) slit diaphragm and is required for kidney ultrafiltration. Down-regulation or mislocalization of nephrin has been observed in diabetic kidney disease (DKD), characterized by albuminuria. Here, we investigate the role of protein kinase C and casein kinase 2 substrate in neurons 2 (PACSIN2), a regulator of endocytosis and recycling, in the trafficking of nephrin and development of DKD. We observe that PACSIN2 is up-regulated and nephrin mislocalized in podocytes of obese Zucker diabetic fatty (ZDF) rats that have altered renal function. In cultured podocytes, PACSIN2 and nephrin colocalize and interact. We show that nephrin is endocytosed in PACSIN2-positive membrane regions and that PACSIN2 overexpression increases both nephrin endocytosis and recycling. We identify rabenosyn-5, which is involved in early endosome maturation and endosomal sorting, as a novel interaction partner of PACSIN2. Interestingly, rabenosyn-5 expression is increased in podocytes in obese ZDF rats, and,

Topics: Adaptor Proteins, Signal Transducing; Animals; Carrier Proteins; Cytoskeletal Proteins; Diabetes Mellitus; Diabetic Nephropathies; Gene Expression Regulation; Humans; Membrane Proteins; Mice; Obesity; Podocytes; Protein Transport; Proteins; Rats, Zucker; Up-Regulation; Vesicular Transport Proteins

Nephrin, an immunoglobulin-like protein essential for the function of the glomerular podocyte and regulated in diabetic nephropathy, is also expressed in pancreatic beta-cells, where its function remains unknown. The aim of this study was to investigate whether diabetes modulates nephrin expression in human pancreatic islets and to explore the role of nephrin in beta-cell function.. Nephrin expression in human pancreas and in MIN6 insulinoma cells was studied by Western blot, PCR, confocal microscopy, subcellular fractionation, and immunogold labeling. Islets from diabetic (n = 5) and nondiabetic (n = 7) patients were compared. Stable transfection and siRNA knockdown in MIN-6 cells/human islets were used to study nephrin function in vitro and in vivo after transplantation in diabetic immunodeficient mice. Live imaging of green fluorescent protein (GFP)-nephrin-transfected cells was used to study nephrin endocytosis.. Nephrin was found at the plasma membrane and on insulin vesicles. Nephrin expression was decreased in islets from diabetic patients when compared with nondiabetic control subjects. Nephrin transfection in MIN-6 cells/pseudoislets resulted in higher glucose-stimulated insulin release in vitro and in vivo after transplantation into immunodeficient diabetic mice. Nephrin gene silencing abolished stimulated insulin release. Confocal imaging of GFP-nephrin-transfected cells revealed nephrin endocytosis upon glucose stimulation. Actin stabilization prevented nephrin trafficking as well as nephrin-positive effect on insulin release.. Our data suggest that nephrin is an active component of insulin vesicle machinery that may affect vesicle-actin interaction and mobilization to the plasma membrane. Development of drugs targeting nephrin may represent a novel approach to treat diabetes.

Topics: Animals; Cell Membrane; Diabetes Mellitus; Diabetes Mellitus, Experimental; DNA Primers; Gene Expression Regulation; Glucose; Humans; Insulin; Insulin Secretion; Islets of Langerhans; Islets of Langerhans Transplantation; Membrane Proteins; Mice; Polymerase Chain Reaction; Reference Values; RNA, Small Interfering; Transfection; Transplantation, Heterologous

Microalbuminuria is an early lesion during the development of diabetic nephropathy. The loss of high molecular weight proteins in the urine is usually associated with decreased expression of slit diaphragm proteins. Nephrin, is the major component of the glomerular slit diaphragm and loss of nephrin has been well described in rodent models of experimental diabetes as well as in human diabetic nephropathy.. In this manuscript we analyzed the role of PKC-alpha (PKCalpha) on endocytosis of nephrin in podocytes. We found that treatment of diabetic mice with a PKCalpha-inhibitor (GO6976) leads to preserved nephrin expression and reduced proteinuria. In vitro, we found that high glucose stimulation would induce PKCalpha protein expression in murine and human podocytes. We can demonstrate that PKCalpha mediates nephrin endocytosis in podocytes and that overexpression of PKCalpha leads to an augmented endocytosis response. After PKC-activation, we demonstrate an inducible association of PKCalpha, PICK1 and nephrin in podocytes. Moreover, we can demonstrate a strong induction of PKCalpha in podocytes of patients with diabetic nephropathy.. We therefore conclude that activation of PKCalpha is a pathomechanistic key event during the development of diabetic nephropathy. PKCalpha is involved in reduction of nephrin surface expression and therefore PKCalpha inhibition might be a novel target molecule for anti-proteinuric therapy.

Topics: Animals; Diabetes Mellitus; Diabetic Nephropathies; Endocytosis; Gene Expression Regulation, Enzymologic; Glucose; Humans; Membrane Proteins; Mice; Podocytes; Protein Kinase C-alpha

To evaluate the effect of bone morphogenic protein 7 (BMP-7) on nephrin expression and distribution in diabetic rat kidneys.. Twenty rats with diabetes mellitus (DM) induced by streptozotocin (STZ) injection were randomly divided into DM model group and BMP-7 treatment group, with another 10 normal rats serving as the normal control group. The rats in BMP-7 group received intraperitoneal human recombinant BMP-7 injections at 30 microg/kg twice a week for 24 consecutive weeks, while normal saline was administered in rats of the other two groups. Blood glucose and 24 hour urinary protein and creatinine (Ccr) were measured at 8, 16 and 24 weeks, and the rats were sacrificed at 24 weeks to obtain the renal tissues for detecting the expression and distribution of nephrin using immunofluorescence assay and RT-PCR and for examining the expressions of transforming growth factor-beta1 (TGF-beta1) and WT1 using immunohistochemistry.. Compared with the normal control group, the DM model group showed significantly increased 24 hour urinary protein, kidney to body weight ratio and TGF-beta1 expression, but had lowered Ccr, glomerular podocyte number and nephrin expression. The linear distribution of nephrin along the capillary loops as found in the normal control group became granular in the kidney of diabetic rats. The rats in BMP-7 group showed less urinary protein excretion, lower TGF-beta1 expression and greater glomerular podocyte number than those in the DM group, and the expression and distribution of nephrin remained normal in the kidney.. Administration of BMP-7 can significantly suppress the down-regulation of nephrin expression and maintain its normal distribution in the podocytes in diabetic rats possibly in association with a direct suppression of TGF-betasignaling.

Topics: Animals; Blood Glucose; Body Weight; Bone Morphogenetic Protein 7; Cell Count; Diabetes Mellitus; Gene Expression Regulation; Humans; Kidney; Male; Membrane Proteins; Microscopy, Electron, Transmission; Organ Size; Podocytes; Rats; Rats, Sprague-Dawley; RNA, Messenger; Transforming Growth Factor beta1

Podocyte-specific, doxycycline (DOX)-inducible overexpression of soluble vascular endothelial growth factor (VEGF) receptor-1 (sFlt-1) in adult mice was used to investigate the role of the VEGF-A/VEGF receptor (VEGFR) system in diabetic glomerulopathy.. We studied nondiabetic and diabetic transgenic mice and wild-type controls treated with vehicle (VEH) or DOX for 10 weeks. Glycemia was measured by a glucose-oxidase method and blood pressure by a noninvasive technique. sFlt-1, VEGF-A, VEGFR2, and nephrin protein expression in renal cortex were determined by Western immunoblotting; urine sFlt-1, urine free VEGF-A, and albuminuria by enzyme-linked immunosorbent assay; glomerular ultrastructure by electron microscopy; and VEGFR1 and VEGFR2 cellular localization with Immunogold techniques.. Nondiabetic DOX-treated transgenic mice showed a twofold increase in cortex sFlt-1 expression and a fourfold increase in sFlt-1 urine excretion (P < 0.001). Urine free VEGF-A was decreased by 50%, and cortex VEGF-A expression was upregulated by 30% (P < 0.04). VEGFR2 expression was unchanged, whereas its activation was reduced in DOX-treated transgenic mice (P < 0.02). Albuminuria and glomerular morphology were similar among groups. DOX-treated transgenic diabetic mice showed a 60% increase in 24-h urine sFlt-1 excretion and an approximately 70% decrease in urine free VEGF-A compared with VEH-treated diabetic mice (P < 0.04) and had lower urine albumin excretion at 10 weeks than VEH-treated diabetic (d) mice: d-VEH vs. d-DOX, geometric mean (95% CI), 117.5 (69-199) vs. 43 (26.8-69) mug/24 h (P = 0.003). Diabetes-induced mesangial expansion, glomerular basement membrane thickening, podocyte foot-process fusion, and transforming growth factor-beta1 expression were ameliorated in DOX-treated diabetic animals (P < 0.05). Diabetes-induced VEGF-A and nephrin expression were not affected in DOX-treated mice.. Podocyte-specific sFlt-1 overexpression ameliorates diabetic glomerular injury, implicating VEGF-A in the pathogenesis of this complication.

Topics: Animals; Blotting, Western; Diabetes Complications; Diabetes Mellitus; Diabetic Nephropathies; Doxycycline; Enzyme-Linked Immunosorbent Assay; Gene Expression; Humans; Kidney Glomerulus; Membrane Proteins; Mice; Mice, Transgenic; Microscopy, Electron; Podocytes; Vascular Endothelial Growth Factor A; Vascular Endothelial Growth Factor Receptor-1; Vascular Endothelial Growth Factor Receptor-2

Diabetes mellitus is a major health problem across the world. Diabetic retinopathy (DR) and nephropathy are two of the major complications of diabetes. DR is the leading cause of blindness and diabetic nephropathy is the leading cause of end-stage renal failure. We have examined the potential value of circulating nucleic acids in the detection and monitoring of these two complications of diabetes. mRNA for nephrin was significantly higher in all diabetics compared to healthy controls and it was significantly higher in normoalbuminuric patients compared to healthy controls. This may indicate progression to microalbuminuric stage. Circulating rhodopsin mRNA was detectable in healthy subjects and in diabetic patients. It was significantly raised in diabetic patients with retinopathy. Higher rhodopsin mRNA in diabetic patients without retinopathy suggests that some of them may go on to develop it or already have it subclinically. Circulating nucleic acids have the potential to be noninvasive molecular tests for diabetic complications.

Topics: Adult; Aged; Diabetes Complications; Diabetes Mellitus; Humans; Membrane Proteins; Middle Aged; Nucleic Acids; Rhodopsin