BioProject

Microarray analysis reveals up-regulation of retinoic acid and hepatocyte growth factor related signaling pathways by pro-insulin C-peptide in kidney proximal tubular cells: Antagonism of the pro-fibrotic effects of TGF-b1 Novel signaling roles for C-peptide have recently been discovered with evidence that it can ameliorate complications of type 1 diabetes. More...

Microarray analysis reveals up-regulation of retinoic acid and hepatocyte growth factor related signaling pathways by pro-insulin C-peptide in kidney proximal tubular cells: Antagonism of the pro-fibrotic effects of TGF-b1 Novel signaling roles for C-peptide have recently been discovered with evidence that it can ameliorate complications of type 1 diabetes. Here we sought to identify new pathways regulated by C-peptide of relevance to the pathophysiology of diabetic nephropathy. Microarray analysis was performed to identify genes regulated by either C-peptide and/or transforming growth factor beta 1 (TGF-β1) in a human proximal tubular cell line, HK-2. Expression of retinoic acid receptor β (RARβ), hepatcoyte growth factor (HGF), cellular retinoic acid binding protein II (CRABPII), vimentin, E-cadherin, Snail and β-catenin was assessed by immunoblotting. The cellular localisation of vimentin and β-catenin was determined by immunocytochemistry. Changes in cell morphology were assessed by phase contrast microscopy. Gene expression profiling demonstrated differential expression of 953 and 1,458 genes after C-peptide exposure for 18h or 48h respectively. From these, members of the anti-fibrotic retinoic acid (RA) and HGF signaling pathways were selected. Immunoblotting demonstrated that C-peptide increased RARβ, CRABPII and HGF. We confirmed a role for RA in reversal of TGF-β1-induced changes associated with epithelial-mesenchymal transition (EMT), including expression changes in Snail, E-cadherin, vimetin and redistribution of β-catenin. Importantly, these TGF-β1-induced changes were inhibited by C-peptide. Further, effects of TGF-β1 on Snail and E-cadherin expression were blocked by HGF and inhibitory effects of C-peptide were removed by blockade of HGF activity. This study identifies a novel role for HGF as an effector of C-peptide, possibly via an RA signaling pathway, highlighting C-peptide as a potential therapy for diabetic nephropathy. Overall design: For microarray analyses, all treatments were performed in triplicate to yield 18 flasks, and RNA from each flask hybridized to a separate chip to give an n of 3 for each of 6 treatments. Flasks were subjected to identical media changes and cells cultured for identical periods in media without supplements. In all experiments, cells were serum-starved overnight before agonist addition. Treatments were initiated such that 18h and 48h incubation periods ended coincidentally and all RNA was prepared at this point. Less...