title: Myofibroblasts exhibit enhanced fibronectin assembly that is intrinsic to their contractile phenotype.
abstract: Myofibroblasts have increased expression of contractile proteins and display augmented contractility. It is not known if the augmented contractile gene expression characterizing the myofibroblast phenotype impacts its intrinsic ability to assemble fibronectin (FN) and extracellular matrix. In this study we investigated whether myofibroblasts displayed increased rates of FN fibril assembly when compared with their undifferentiated counterparts. Freshly plated myofibroblasts assemble exogenous FN (488-FN) into a fibrillar matrix more rapidly than fibroblasts that have not undergone myofibroblast differentiation. The augmented rate of FN matrix formation by myofibroblasts was dependent on intact Rho/Rho kinase (ROCK) and myosin signals inasmuch as treatment with Y27632 or blebbistatin attenuated 488-FN assembly. Inhibiting contractile gene expression by pharmacologic disruption of the transcription factors megakaryoblastic leukemia-1 (MKL1)/serum response factor (SRF) during myofibroblast differentiation resulted in decreased contractile force generation and attenuated 488-FN incorporation although not FN expression. Furthermore, disruption of the MKL1/SRF target gene, smooth muscle α-actin (α-SMA) via siRNA knockdown resulted in attenuation of 488-FN assembly. In conclusion, this study demonstrates a linkage between increased contractile gene expression, most importantly α-SMA, and the intrinsic capacity of myofibroblasts to assemble exogenous FN into fibrillar extracellular matrix.
authors: From the Departments of Medicine and.
authors: Elizabeth E
authors: EE
authors: Torr
authors: From the Departments of Medicine and.
authors: Caitlyn R
authors: CR
authors: Ngam
authors: From the Departments of Medicine and.
authors: Ksenija
authors: K
authors: Bernau
authors: Surgery, University of Wisconsin-Madison, School of Medicine and Public Health, Madison, Wisconsin 53792.
authors: Bianca
authors: B
authors: Tomasini-Johansson
authors: From the Departments of Medicine and.
authors: Benjamin
authors: B
authors: Acton
authors: From the Departments of Medicine and nsandbo@medicine.wisc.edu.
authors: Nathan
authors: N
authors: Sandbo
mesh_terms: D000199:Actins / Q000378:metabolism; D002454:Cell Differentiation; D002478:Cells, Cultured; D005109:Extracellular Matrix / Q000378:metabolism; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism; D005353:Fibronectins / Q000378:metabolism*; D006801:Humans; D058628:Myofibroblasts / Q000166:cytology / Q000378:metabolism*; D011658:Pulmonary Fibrosis / Q000378:metabolism; D026362:Serum Response Factor / Q000378:metabolism; D015534:Trans-Activators / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000378:metabolism
chemical_list: D000199:Actins; D005353:Fibronectins; C431575:MRTFA protein, human; D026362:Serum Response Factor; D015534:Trans-Activators; D016212:Transforming Growth Factor beta
keywords: Extracellular Matrix; Fibroblast; Fibronectin; Megakaryoblastic Leukemia-1; Myofibroblast; Serum Response Factor; Smooth Muscle α-Actin; Transforming Growth Factor β (TGF-B)
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