Inhibition of TRPC6 suppressed TGFβ-induced fibroblast-myofibroblast transdifferentiation in renal interstitial NRK-49F cells

Renal fibrosis is a global health concern with limited curative treatment. Canonical transient receptor potential channel 6 (TRPC6), a nonselective cation channel, has been shown to regulate the renal fibrosis in murine models. However, the molecular mechanism is unclear. Fibroblast-myofibroblast transdifferentiation is one of the critical steps in the progression of renal fibrosis. In the present study, we demonstrate that transforming growth factor (TGF)-β1 exposure significantly increases the TRPC6 expression in renal interstitial fibroblast NRK-49F cells. Pharmacological inhibition of TRPC6 and knockdown of Trpc6 by siRNA alleviate TGF-β1-increased expression levels of α-smooth muscle actin (α-SMA) and collagen I, two key markers of myofibroblasts. Although direct activation of TRPC6 by 1-oleoyl-2-acetyl-sn-glycerol (OAG) does not affect the expression of α-SMA and collagen I, OAG potentiates TGF-β1-induced fibroblast-myofibroblast transdifferentiation. Further study demonstrates that TGF-β1 exposure increases the phosphorylation level of p38 and Yes-associated protein (YAP) translocation into the nuclei. Inhibition of p38 and YAP decreases TGF-β1-enhanced TRPC6 and α-SMA expression. In conclusion, we demonstrate that TRPC6 is a key regulator of TGF-β1-induced fibroblast-myofibroblast transdifferentiation and provides the mechanism of how TGF-β1 exposure regulates TRPC6 expression in NRK-49F fibroblasts.