Serum response factor provokes epithelial-mesenchymal transition in renal tubular epithelial cells of diabetic nephropathy.

We investigated the role of serum response factor (SRF) in epithelial-mesenchymal transition (EMT) of renal tubular epithelial cells (TECs) in diabetic nephropathy (DN). The expression of SRF, epithelial markers (E-cadherin and ZO-1), and mesenchymal markers (fibronectin, collagen-1, α-SMA, FSP-1) was examined in human proximal renal tubular epithelial cells (HK-2 cells) or renal medulla tissues following high glucose. SRF was upregulated by SRF plasmids and downregulated by CCG-1423 (a small molecule inhibitor of SRF) to investigate how SRF influenced EMT in TECs of DN. Streptozotocin was used to generate DM in rats. In HK-2 cells after high-glucose treatment and renal medulla tissues of diabetic rats, SRF, fibronectin, collagen-1, α-SMA, and FSP-1 increased, while E-cadherin and ZO-1 declined. SRF overexpression in HK-2 cells induced expression of Snail, an important transcription factor mediating EMT. Blockade of SRF by CCG-1423 reduced Snail induction and protected TECs from EMT both in vitro and in vivo. Together, increased SRF activity promotes EMT in TECs and dysfunction in DN. Targeting SRF by small molecule inhibitor may be an attractive therapeutic strategy for DN.