248 - TRPV4 Has a Role as a Ca2+–Permeable Channel in the Differentiation of Human Ventricular Fibroblasts Into Myofibroblasts

Abstract

Introduction: Cardiac fibroblasts (CFs) are the predominant cell types that reside in the interstitial space of the heart. In response to pathological stimuli, CFs are stimulated to undergo phenotypic modulation and become myofibroblasts that are hypersecretory and highly contractile and which deposit excessive extracellular matrix proteins. Ca2 + signals are essential to a diversity of cellular functions, including differentiation, gene expression, cell proliferation, and growth. CaV1.2-mediated L-type Ca2+ current (ICa,L) is a fundamental myocardial calcium entry channel, but CFs do not typically express the voltage-gated Ca2+ channel. Transient receptor potential (TRP) channels are nonselective calcium entry channels, and their function has been studied in many cell types. TRP is expressed in a cell-specific manner, and its role has not been evaluated in human ventricular fibroblasts. Methods: Here, we evaluate the role of the TRP channel in the differentiation of human ventricular fibroblasts into myofibroblasts. Results: Concordant with previous studies, Ca2+ was found in the current study to be an essential component in fibroblast differentiation. Intracellular chelation inhibited p-ERK expression and fibroblast differentiation. TRPV4 mRNA was expressed in human ventricular fibroblasts and increased on account of TGF-β1 (2 ng/mL). TRPV4 agonist (GSK1016790A) treatment induced the robust differentiation of fibroblasts into myofibroblasts. TRPV4 antagonist (RN-9893) significantly inhibited TGF-β1-induced p–ERK expression and the differentiation of CFs. Using ratio Ca2+ imaging measurements, we found a robust increase in Ca2+ influx after fibroblasts were treated with TRPV4 agonist (GSK1016790A). Conclusions: These results demonstrate that TRPV4 has a role as a Ca2+–permeable channel in the differentiation of human ventricular fibroblasts into myofibroblasts, through the ERK signaling pathway.