A TRPC6-Dependent Pathway for Myofibroblast Transdifferentiation and Wound Healing In Vivo

Abstract

Summary After injury or cytokine stimulation, fibroblasts transdifferentiate into myofibroblasts, contractile cells that secrete extracellular matrix for wound healing and tissue remodeling. Here, a genome-wide screen identified TRPC6, a Ca2+ channel necessary and sufficient for myofibroblast transformation. TRPC6 overexpression fully activated myofibroblast transformation, while fibroblasts lacking Trpc6 were refractory to transforming growth factor-β (TGFβ) and angiotensin II-induced transdifferentiation. Trpc6 gene-deleted mice showed impaired dermal and cardiac wound healing after injury. The pro-fibrotic ligands TGFβ and angiotensin II induced TRPC6 expression through p38 mitogen-activated protein kinase (MAPK) - serum response factor (SRF) signaling via the TRPC6 promoter. Once induced, TRPC6 activates the Ca2+-responsive protein phosphatase calcineurin, which itself induced myofibroblast transdifferentiation. Moreover, inhibition of calcineurin prevented TRPC6-dependent transdifferentiation and dermal wound healing. These results demonstrate an obligate function for TRPC6 and calcineurin in promoting myofibroblast differentiation, suggesting a comprehensive pathway for myofibroblast formation in conjunction with TGFβ, p38 MAPK and SRF.

Combined TRPC3 and TRPC6 blockade by selective small-molecule or genetic deletion inhibits pathological cardiac hypertrophy

“…They are normally expressed at very low levels in myocytes, but levels are increased in cardiac disease, such as pressure overload (3,4,8,9). TRPC6 is essential for the transformation of fibroblasts to myofibroblasts and corresponding scar formation (10). Both species can be directly activated by diacylglycerol coupled to Gαq signaling, and TRPC6 is also stimulated by mechanical stretching and oxidative stress (7,11,12).…”

Activation of MRTF-A–dependent gene expression with a small molecule promotes myofibroblast differentiation and wound healing

“…Based on our finding that isoxazole does not affect Smad2/3 phosphorylation, and mutation of CArG boxes abolishes responsiveness to isoxazole, the phenotypic change elicited by isoxazole likely occurs via the promotion of MRTF/SRF activity. Importantly, a recent study using a similar SMA-luc-based screen identified the TRPC6 Ca 2+ channel as a key agonist of TGF-β1/ SRF-dependent myofibroblast differentiation and wound healing (35). Isoxazole has been shown to activate the G-protein-coupled receptor GPR68, leading to Ca 2+ signaling (36), which could potentially couple to this pathway.…”

Functional Alterations of Ion Channels From Cardiac Fibroblasts in Heart Diseases

“…The role of some of these channels, such as TRPC1, TRPC6, TRPM7 and Na + channels, in human CF proliferation and differentiation as well as BKCa channel in fibroblast proliferation or apoptosis (depending on metabolic state), has been demonstrated; yet, several questions remain unanswered. Although TRPC6 is reported to be necessary and sufficient for myofibroblast transformation, 29 the existence of other TRP channels, and their activation resulting in the same effect, is puzzling. Whether there is any crosstalk between these channels or any intermediary signaling mechanisms to coordinate the function is unclear.…”

“…Fibroblasts lacking TRPC6 did not respond to TGF-β1-or angiotensin II-induced transdifferentiation, and cardiac wound healing was impaired in TRPC6-knockout mice. 29 The profibrotic ligands TGF-β1 and angiotensin II induced TRPC6 expression through p38-MAPK serum response factor signaling via the TRPC6 promoter. Small interfering RNA knockdown of TRPC6 reduced the diacylglycerol analogue OAG-, thapsigargin-and angiotensin II-induced Ca 2+ entry in human CFs.…”