Effects of overexpressed SGK1 on the secretion of fibronectin in human podocytes / 中国病理生理杂志

ABSTRACT

AIM:To investigate the effects of high concentration of glucose on the expressions of serum and glucocorticoid induced protein kinase 1 (SGK1) and fibronectin in human podocytes and detect the production of fibronectin in human podocytes transfected with active and mutant forms of SGK1.METHODS: The expressions of SGK1 and fibronectin in human podocytes exposed in high glucose for 24 h were detected by using Western blotting. Human podocytes were transfected with three kinds of plasmid pIRES2-EGFP-SGK1SD (SGK1-active plasmid), pIRES2-EGFP-SGK1KN (SGK1-mutant plasmid) and pIRES2-EGFP (empty vector plasmide). The synthesis levels of fibronectin were detected by immunofluorescence.RESULTS: The expression of SGK1 in normal human podocytes was observed and the expression level was up-regulated in podocytes exposed to high glucose for 24 h (50?4 vs 35?3), parallelly with the high expression of fibronectin (19?4 vs 12?2). The secretion of fibronectin was increased obviously in SGK1-active plasmid (SGK1SD) transfected podocytes compared with the vector transfected podocytes. Whereas, the fibronectin level was decreased significantly but not completely abolished in SGK1-mutant plasmid (SGK1KN) transfected podocytes, compared with SGK1SD transfected podocytes. CONCLUSION: SGK1 may be involved in the synthesis of fibronectin in human podocytes induced by high glucose and play a critical role in the activation of human podocytes during early stage of diabetic nephropathy.