Calreticulin is involved in diabetic nephropathy through inducing epithelial mesenchymal transition
Abstract：Diabetic nephropathy is a common complication of type 2 diabetes mellitus. Production of reactive oxygen species (ROS) caused by hyperglycemia is associated with fibrosis. The aim of this research is to investigate the role of calreticulin (CRT), an endoplasmic reticulum chaperone, in diabetic nephropathy. Type 2 diabetic mice (C57BL/Ksj db/db) and normal control mice (db/m) were fed for 8 weeks. Blood glucose and urinary microalbuminuria (mAlb) were measured every 2 weeks. At the end of the experimental period, kidney tissues were excised and used for histological tests. CRT expression was blocked by siRNA in human proximal tubular epithelial HK-2 cells and the cells were cultured with high glucose (25 mmol/L) medium. CRT expression was tested with RT-PCR. Cellular migration ability was tested by wound healing assay. Protein levels of vimentin, matrix metalloproteinase 2 (MMP-2), E-cadherin, and phospho-p65 NF-κB were measured by Western blot. Compared with db/m mice, db/db mice exhibited higher levels of blood glucose and urinary mAlb. Western blot showed that CRT expression was increased in the kidneys of db/db mice. Exposing to high glucose increased CRT expression in HK-2 cells. Blocking CRT expression in HK-2 cells inhibited cellular migration ability. Meanwhile, expression of mesenchymal markers vimentin and MMP2 were down-regulated; expression of epithelial marker E-cadherin was up-regulated. Phospho-p65 NF-κB was also down-regulated when suppressing CRT expression. CRT was involved in process of diabetic nephropathy by inducing epithelial mesenchymal transition via NF-κB signaling pathway.