Expression of the slit-diaphragm protein, nephrin, in experimental diabetic nephropathy: differing effects of anti-proteinuric therapies

Foot process effacement is an important feature of early diabetic nephropathy (DN) which is closely related to the development of albuminuria. Under certain nephrotic conditions, the integrity and function of the glomerular slit diaphragm (SD) structure were impaired and replaced by the tight junction (TJ) structure, resulting in so-called SD-TJ transition, which could partially explain the effacement of foot processes at the molecular level. However, the mechanism underlying the SD-TJ transition has not been described in DN. Here, we demonstrated that impaired autophagic flux blocked p62 mediated degradation of ZO-1 (TJ protein) and promoted podocytes injury via activation of caspase 3 and caspase 8. Interestingly, the expression of VDR in podocytes was decreased under diabetic condition which impaired autophagic flux through down-regulating Atg3. Of note, we also found that VDR abundance was negatively associated with impaired autophagic flux and SD-TJ transition in the glomeruli from human renal biopsy samples with DN. Furthermore, VDR activation improved autophagic flux and attenuated SD-TJ transition in the glomeruli of diabetic animal models. In conclusion, our data provided the novel insight that VDR/Atg3 axis deficiency resulted in SD-TJ transition and foot processes effacement via blocking p62-mediated autophagy pathway in DN.<br>

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Glomerular clusterin expression is increased in diabetic nephropathy and protects against oxidative stress-induced apoptosis in podocytes

Scientific Reports ◽

10.1038/s41598-020-71629-z ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Junling He ◽

Kyra L. Dijkstra ◽

Kim Bakker ◽

Pascal Bus ◽

Jan A. Bruijn ◽

...

Keyword(s):

Oxidative Stress ◽

Diabetic Nephropathy ◽

Mrna Expression ◽

Kidney Diseases ◽

Slit Diaphragm ◽

Oxidative Stress Marker ◽

Induced Apoptosis ◽

Vitro Analysis ◽

Clusterin Expression

Abstract Clusterin, a glycoprotein encoded by the CLU gene, is expressed in many tissues, including the kidney, and clusterin expression is upregulated in the glomeruli of patients with various forms of kidney disease. Here, we investigated the role of clusterin in diabetic nephropathy (DN). In this study, we found that glomerular clusterin expression was increased in both patients with DN and streptozotocin-induced diabetic mice and that it co-localised with the podocyte marker WT1, indicating clusterin is expressed in podocytes. In our in vitro analysis, we found no significant change in CLU mRNA expression in podocytes following stimulation with high glucose and angiotensin II; in contrast, CLU mRNA expression was significantly upregulated following methylglyoxal stimulation. Methylglyoxal treatment also significantly decreased the mRNA expression of the slit diaphragm markers ZO-1 and NEPH1 and significantly increased the mRNA expression of the oxidative stress marker HO-1. Lastly, we showed that pre-incubating podocytes with recombinant human clusterin protein increased podocyte survival, prevented slit diaphragm damage, and reduced oxidative stress‒induced apoptosis following methylglyoxal stimulation. Taken together, our results indicate that glomerular clusterin is upregulated in DN, and this increase in clusterin expression may protect against oxidative stress-induced apoptosis in podocytes, providing a possible new therapeutic target for DN and other kidney diseases.

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The number of podocyte and slit diaphragm is decreased in experimental diabetic nephropathy

Acta Cirurgica Brasileira ◽

10.1590/s0102-86502006000200006 ◽

2006 ◽

Vol 21 (2) ◽

pp. 87-91 ◽

Cited By ~ 7

Author(s):

Mauro Masson Lerco ◽

Célia Sperandéo Macedo ◽

Reinaldo José Silva ◽

Daniela de Oliveira Pinheiro ◽

César Tadeu Spadella

Keyword(s):

Body Weight ◽

Diabetic Nephropathy ◽

Diabetic Rats ◽

Slit Diaphragm ◽

Diabetic Rat ◽

Severe Diabetes ◽

Foot Process ◽

The Right ◽

Alloxan Injection

PURPOSE: To determine the number of podocyte, slit diaphragms, slit diaphragm extensions and GBM thickness in diabetic nephropathy. METHODS: Sixty "Rattus Wistar"of both sexes weighing 200-300g were divided in two experimental groups: normal group 10 animals, and alloxan diabetic rats - 50 animals. Alloxan was administered in a single IV dose of 42mg/kg body weight. Body weight, water and food intake, diuresis, and blood and urine glucose were determined in both groups before alloxan injection and two weeks, six and twelve months after alloxan injection. Proteinuria was measured at 12 months in both groups. After 12 months animals were sacrificed, and the right kidney processed for electron microscopy. RESULTS: Clear clinical and laboratory signs of severe diabetes were seen, in all alloxan-diabetic rats at all follow-up times. Glomerular basement membrane (GBM) thickening, podocyte number, and slit diaphragm number and extension were determined. GBM of all diabetic rats was significantly thicker (median=0.29µm; semi-interquartile range=0.065µm) than in the normal rats (0.23µm; 0.035µm). Diabetic rat podocyte number (8; 1), slit diaphragm number (4; 1), and slit diaphragm extension (0.021µm; 0.00435µm) were significantly lower than in normal rats (11; 1) and (7; 1.5), and (0.031µm; 0.0058µm). Diabetic rat proteinuria (0.060mg/24h; 0.037mg/24h) was higher than in normal rats (0.00185mg/24h; 0.00055mg/24h). CONCLUSION: Experimental diabetes is associated with significant (p<0.05) changes in podocyte foot process, slit number, slit diaphragm extension, and GBM thickness.

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Proteinuria and the expression of the podocyte slit diaphragm protein, nephrin, in diabetic nephropathy: effects of angiotensin converting enzyme inhibition

Diabetologia ◽

10.1007/s00125-002-0946-y ◽

2002 ◽

Vol 45 (11) ◽

pp. 1572-1576 ◽

Cited By ~ 158

Author(s):

Langham R. ◽

Kelly D. ◽

Cox A. ◽

Thomson N. ◽

Holthöfer H. ◽

...

Keyword(s):

Diabetic Nephropathy ◽

Angiotensin Converting Enzyme ◽

Enzyme Inhibition ◽

Slit Diaphragm ◽

Angiotensin Converting Enzyme Inhibition ◽

Converting Enzyme ◽

Converting Enzyme Inhibition

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VDR/Atg3 Axis Regulates Slit Diaphragm to Tight Junction Transition via p62-mediated Autophagy Pathway in Diabetic Nephropathy

10.2337/figshare.15108672 ◽

2021 ◽

Author(s):

Bin Wang ◽

Jing-yi Qian ◽

Tao-tao Tang ◽

Li-lu Lin ◽

Nan Yu ◽

...

Keyword(s):

Diabetic Nephropathy ◽

Tight Junction ◽

Diabetic Animal ◽

Slit Diaphragm ◽

Autophagic Flux ◽

The Novel ◽

Foot Process ◽

Autophagy Pathway ◽

And Function ◽

Early Diabetic Nephropathy

Foot process effacement is an important feature of early diabetic nephropathy (DN) which is closely related to the development of albuminuria. Under certain nephrotic conditions, the integrity and function of the glomerular slit diaphragm (SD) structure were impaired and replaced by the tight junction (TJ) structure, resulting in so-called SD-TJ transition, which could partially explain the effacement of foot processes at the molecular level. However, the mechanism underlying the SD-TJ transition has not been described in DN. Here, we demonstrated that impaired autophagic flux blocked p62 mediated degradation of ZO-1 (TJ protein) and promoted podocytes injury via activation of caspase 3 and caspase 8. Interestingly, the expression of VDR in podocytes was decreased under diabetic condition which impaired autophagic flux through down-regulating Atg3. Of note, we also found that VDR abundance was negatively associated with impaired autophagic flux and SD-TJ transition in the glomeruli from human renal biopsy samples with DN. Furthermore, VDR activation improved autophagic flux and attenuated SD-TJ transition in the glomeruli of diabetic animal models. In conclusion, our data provided the novel insight that VDR/Atg3 axis deficiency resulted in SD-TJ transition and foot processes effacement via blocking p62-mediated autophagy pathway in DN.<br>

Download Full-text