title: TRPV4 channels mediate cardiac fibroblast differentiation by integrating mechanical and soluble signals.
abstract: The phenotypic switch underlying the differentiation of cardiac fibroblasts into hypersecretory myofibroblasts is critical for cardiac remodeling following myocardial infarction. Myofibroblasts facilitate wound repair in the myocardium by secreting and organizing extracellular matrix (ECM) during the wound healing process. However, the molecular mechanisms involved in myofibroblast differentiation are not well known. TGF-β has been shown to promote differentiation and this, combined with the robust mechanical environment in the heart, lead us to hypothesize that the mechanotransduction and TGF-β signaling pathways play active roles in the differentiation of cardiac fibroblasts to myofibroblasts. Here, we show that the mechanosensitve ion channel TRPV4 is required for TGF-β1-induced differentiation of cardiac fibroblasts into myofibroblasts. We found that the TRPV4-specific antagonist AB159908 and siRNA knockdown of TRPV4 significantly inhibited TGFβ1-induced differentiation as measured by incorporation of α-SMA into stress fibers. Further, we found that TGF-β1-induced myofibroblast differentiation was dependent on ECM stiffness, a response that was attenuated by TRPV4 blockade. Finally, TGF-β1 treated fibroblasts exhibited enhanced TRPV4 expression and TRPV4-mediated calcium influx compared to untreated controls. Taken together these results suggest for the first time that the mechanosensitive ion channel, TRPV4, regulates cardiac fibroblast differentiation to myofibroblasts by integrating signals from TGF-β1 and mechanical factors.
authors.affiliation: Department of Integrative Medical Sciences, Northeast Ohio Medical University, Rootstown, OH 44272, USA.
authors.forename: Ravi K
authors.initials: RK
authors.lastname: Adapala
authors.forename: Roslin J
authors.initials: RJ
authors.lastname: Thoppil
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Luther
authors.forename: Sailaja
authors.initials: S
authors.lastname: Paruchuri
authors.forename: J Gary
authors.initials: JG
authors.lastname: Meszaros
authors.forename: William M
authors.initials: WM
authors.lastname: Chilian
authors.forename: Charles K
authors.initials: CK
authors.lastname: Thodeti
mesh_terms: D000818:Animals; D020013:Calcium Signaling; D002454:Cell Differentiation; D000081007:Cymenes; D005109:Extracellular Matrix / Q000378:metabolism / Q000502:physiology; D005347:Fibroblasts / Q000502:physiology*; D055785:Gene Knockdown Techniques; D008297:Male; D040542:Mechanotransduction, Cellular; D039821:Monoterpenes / Q000494:pharmacology; D009206:Myocardium / Q000166:cytology; D058628:Myofibroblasts / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D050053:TRPM Cation Channels / Q000037:antagonists & inhibitors / Q000378:metabolism; D050916:TRPV Cation Channels / Q000235:genetics / Q000378:metabolism*; D053773:Transforming Growth Factor beta1 / Q000502:physiology
chemical_list: D000081007:Cymenes; D039821:Monoterpenes; D034741:RNA, Small Interfering; D050053:TRPM Cation Channels; D050916:TRPV Cation Channels; D053773:Transforming Growth Factor beta1; C486577:Trpv4 protein, rat; C073316:carvacrol; C486584:Trpm7 protein, rat