Involvement of Mechanosensitive Channel Piezo1 in Renal Fibrosis

Abstract

Renal fibrosis is the final common pathway of numerous progressive kidney diseases, characterized by deposition of extracellular matrix in the tubulointerstitial areas, leading to scar formation and increased tissue stiffness of kidney. The underlying mechanisms of renal fibrosis are not fully identified. Piezo1 is known as a mechanosensitive nonselective cation channel, playing an important role in many physiological and pathological processes. The purpose of the current study is to investigate the role of Piezo1 in renal fibrosis and potential molecular mechanism. In human fibrotic kidneys, Piezo1 protein expression was markedly upregulated. The abundance of Piezo1 protein in kidneys of mice was instantly increased after 30 minutes of unilateral ureteral obstruction (UUO), and persistently increased at the 3rd and the 7th days after UUO. Inhibition of Piezo1 with GsMTx4 dramatically ameliorated UUO-induced renal fibrosis. Mechanical stretch induced Piezo1 activation and epithelial-mesenchymal transition (EMT) in human proximal tubular HK2 cells, as seen in increased abundance of a fibrotic marker fibronectin and decreased expression of an epithelial marker E-cadherin, which were greatly reversed by inhibition or silence of Piezo1. Similarly, in HK2 cells, TGF-β1-induced EMT was significantly inhibited by GsMTx4, whereas a specific Piezo1 agonist Yoda1 markedly induced EMT. In addition, the increased expression of Piezo1 protein was found when HK2 cells were cultured in stiff polyacrylamide hydrogels, mimicking the natural accumulation of ECM. Stimulation of Piezo1 by Yoda1 caused calcium influx in association with activation of calpain2 and integrinβ1. Also, Yoda1 promoted an interaction between ECM and integrinβ1 in HK2 cells. In conclusion, activation of Piezo1 is involved in the development of renal fibrosis and EMT in HK2 cells, likely through calcium-calpain2-integrinβ1 pathway.