The molecular mechanisms of SM22alpha in cytoskeleton remodeling of vascular smooth muscle cells / 中国应用生理学杂志

ABSTRACT

<p><b>AIM</b>To investigate the molecular mechanisms of smooth muscle 22 alpha (SM22alpha) whereby cytoskeleton remodeling of vascular smooth muscle cells (VSMCs) is regulated.</p><p><b>METHODS</b>Synthetic (dedifferentiated) VSMCs were converted to contractile (differentiated) VSMCs by serum deprivation. Cells were transfected with pEGFP-SM22alpha, and localization of SM22alpha and its relationship with F-actin were observed through fluorescence microscopy. Fractional extraction of proteins and Western blotting were used to detect polymerization of SM alpha-actin in antisense-pcD2-SM22alpha-transfected VSMCs.Furthermore, effect of SM22alpha on F-actin cross-linking was observed by F-actin polymerization experiment.</p><p><b>RESULTS</b>Fluorescence microscopy showed that SM22alpha co-localized with F-actin in contractile VSMCs. Western blotting of protein extracts from F-/G-actin fractions revealed that polymerization of SM alpha-actin was lower in antisense-pcD2-SM22alpha-transfected VSMCs, in which SM alpha-actin mostly existed as soluble G-actin. Moreover, F-actin polymerization in vitro also showed that GST-SM22alpha could promote cross-linking of F-actin to form thick and bundled stress fibres,while extracts from VSMCs transfected with antisense-pcD2-SM22alpha could not effectively induce the polymerization of F-actin.</p><p><b>CONCLUSION</b>SM22alpha acts as a modulator to participate in VSMC cytoskeleton remodeling. It can not only induce polymerization of G-actin to F-actin, but also promote cross-linking of F-actin to bundled stress fibres, indicating its vital role in cytoskeleton remodeling.</p>