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Role of alpha‐smooth muscle actin in myofibroblast formation and function
Author(s) -
Tomasek James J,
Haaksma Carol J
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.5.a80-e
Subject(s) - myofibroblast , actin , granulation tissue , chemistry , smooth muscle , microbiology and biotechnology , biochemistry , wound healing , pathology , endocrinology , immunology , biology , medicine , fibrosis
Myofibroblasts have a contractile phenotype and function which plays a critical role in wound closure. It has been hypothesized that the smooth muscle α‐actin (SMAA) expressed in myofibroblasts is critical for their formation and function. We have used a SMAA null mouse to test this hypothesis. We have found that full‐thickness excisional wounds closed at a similar rate in SMAA null and wild type (WT) mice. In addition, a portion of the SMAA promoter, active in myofibroblasts of WT mice, was active in granulation tissue of excisional wounds in SMAA null mice. Cultured dermal fibroblasts from SMAA null and WT type mice formed stress fibers and supermature focal adhesions similarly in response to TGF‐β1. Also, SMAA null and WT fibroblasts generated similar amounts of contractile force in response to TGF‐β1. Immunostaining and RT‐PCR found smooth muscle γ‐actin (SMGA) to be expressed at much greater levels in SMAA null than WT myofibroblasts and granulation tissue. These results demonstrate that SMAA is not necessary for myofibroblast formation and function; however, SMGA may compensate for the lack of SMAA and may be able to function for SMAA in myofibroblasts. (Funded by NIH grant R01 GM60651)