High glucose promotes the CTGF expression in human mesangial cells via serum and glucocorticoid-induced kinase 1 pathway

Abstract

The role of serum and glucocorticoid-induced kinase 1 (SGK1) pathway in the connective tissue growth factor (CTGF) expression was investigated in cultured human mesangial cells (HMCs) under high glucose. By using RT-PCR and Western blot, the effect of SGK1 on the CTGF expression in HMCs under high glucose was examined. Overexpression of active SGK1 in HMCs transfected with _pIRES₂-EGFP-^S422D hSGK1 (SD) could increase the expression of phosphorylated SGK1 and CTGF as compared with HMCs groups transfected with _pIRES₂-EGFP (FP) under high glucose or normal glucose. Overexpression of inactive SGK1 in HMCs transfected with _pIRES₂-EGFP-^K127N hSGK1 (KN) could decrease phosphorylated SGK1 and CTGF expression as compared with HMCs groups transfected with FP under high glucose. In conclusion, these results suggest that high glucose-induced CTGF expression is mediated through the active SGK1 in HMCs.

Keywords

high glucose / serum and glucocorticoid-induced protein kinase 1 / human mesangial cells / connective tissue growth factor / diabetic nephropathy