title: Force-induced myofibroblast differentiation through collagen receptors is dependent on mammalian diaphanous (mDia).
abstract: The development of fibrosis promotes the differentiation of myofibroblasts, pro-fibrotic cells, which contribute to tissue dysfunction. Myofibroblast differentiation is dependent on actin assembly, which in response to force, is mediated by various actin-binding proteins including the mammalian Diaphanous-related formins (mDia). We examined the role of mDia in the mechano-sensing pathway that leads to force-induced expression of alpha-smooth muscle actin (SMA), a marker and critical determinant of myofibroblast differentiation. In cells treated with siRNA to knockdown mDia and then subjected to tensile force using collagen-coated magnetite beads attached to beta1 integrins, actin assembly was inhibited at bead contact sites. Force-induced nuclear translocation of MRTF-A, a transcriptional co-activator of SMA, was reduced 50% by mDia knockdown. The expression of the transcriptional co-activator of SMA, serum response factor, was reduced by 50% after siRNA knockdown of mDia or by 100% in cells transfected with catalytically inactive mDia. Force-induced activation of the SMA promoter and SMA expression were blocked by knockdown of siRNA of mDia. In anchored collagen gel assays to measure myofibroblast-mediated contraction, knockdown of mDia reduced contraction by 50%. We conclude that mDia plays an important role in the development of force-induced transcriptional activation of SMA and myofibroblast differentiation.
authors.affiliation: CIHR Group in Matrix Dynamics, University of Toronto, Toronto, Ontario M5S 3E2, Canada. matthew.chan@utoronto.ca
authors.forename: Matthew W C
authors.initials: MW
authors.lastname: Chan
authors.forename: Faiza
authors.initials: F
authors.lastname: Chaudary
authors.forename: Wilson
authors.initials: W
authors.lastname: Lee
authors.forename: John W
authors.initials: JW
authors.lastname: Copeland
authors.forename: Christopher A
authors.initials: CA
authors.lastname: McCulloch
mesh_terms: D000199:Actins / Q000378:metabolism; D021581:Active Transport, Cell Nucleus; D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism*; D000818:Animals; D002454:Cell Differentiation; D003094:Collagen / Q000737:chemistry; D005347:Fibroblasts / Q000378:metabolism; D000080865:Formins; D006801:Humans; D011401:Promoter Regions, Genetic; D051381:Rats; D038981:Receptors, Collagen / Q000378:metabolism*; D026362:Serum Response Factor / Q000378:metabolism; D013314:Stress, Mechanical; D013718:Tensile Strength; D015533:Transcriptional Activation
chemical_list: D000199:Actins; D048868:Adaptor Proteins, Signal Transducing; C108962:DIAPH1 protein, human; D000080865:Formins; D038981:Receptors, Collagen; D026362:Serum Response Factor; D003094:Collagen