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SM22α Modulates Vascular Smooth Muscle Cells Phenotype through Bundling F‐actin
Author(s) -
Han Mei,
Dong Lihua,
Shi Jianhong,
Zheng Bin,
Wen Jinkun,
Cheng Yunhui
Publication year - 2008
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.22.1_supplement.744.3
Subject(s) - actin , cytoskeleton , microbiology and biotechnology , actin cytoskeleton , actin remodeling , stress fiber , chemistry , phenotype , in vitro , vascular smooth muscle , biology , cell , biochemistry , smooth muscle , gene , endocrinology
SM22α is a specific marker of contractile smooth muscle cells (SMCs). The recent study did demonstrate a role for SM22α in inhibiting the phenotypic modulation of SMCs from contractile to synthetic cells during atherogenesis. The investigators have showed that SM22α decorated contractile filament bundles in SMCs, and bound to and/or gel actin in vitro. However, it has been found no SM22α actin interaction in vitro or in vivo. These contradictory results suggest that the function and mechanism of SM22α in the actin cytoskeleton reorganization are unknown. We found that overexpression of SM22α induced F‐actin boundling, and forcedly expressed SM22α was incorporated into actin stress fibers. Coimmunoprecipitation and immunofluorescence showed that SM22α directly interacted and colocalized with F‐actin, participating in cytoskeleton reorganization in vascular SMCs that exhibit a differentiated phenotype. Co‐sedimentation assay demonstrated that SM22α facilitates actin filaments assemble into bundles. The blockade of SM22α expression by antisense SM22α transcripts made actin filaments dispersive and slim, and resulted in reduction of F‐/G‐actin ratio, consequently disappearance of cell contraction. This study first demonstrates that SM22α bundles F‐actin via a direct binding to F‐actin, participating in cytoskeleton reorganization in vascular SMCs that exhibit a differentiated phenotype.