Abstract
SM22-alpha, also named transgelin, encoded by the gene TAGLN is a calponin-related protein found in smooth muscle, fibroblast and cancer cells. SM22-alpha was discovered three decades ago but its biological function remains unclear. In addition to an application as a differentiation marker for smooth muscle cells, SM22-alpha has been reported to regulate the structure and dynamics of actin cytoskeleton and cell motility in fibroblasts and cancer cells. Here we report a novel finding that the expression and degradation of SM22-alpha/transgelin are both regulated by mechanical tension. Mass spectrometry detected that SM22-alpha was significantly decreased in mouse aortic rings after incubation under low mechanical tension. Using specific monoclonal antibodies developed against chicken gizzard SM22-alpha, we found high levels of SM22-alpha in human fetal lung fibroblast cells line MRC-5 and primary neonatal mouse skin fibroblasts. Similar to that of calponin 2, the level of SM22-alpha is positively dependent on the mechanical tension in the cytoskeleton as determined by the stiffness of culture substrate. Quantitative RT-PCR demonstrated a transcriptional regulation of TAGLN gene expression by mechanical tension in the cytoskeleton. The cellular localization of SM22-alpha overlaps with that of myosin IIA and blebbistatin inhibition of myosin motor decreased the expression of SM22-alpha. The level of SM22-alpha is decreased in skin fibroblasts isolated from calponin 2 knockout mice compared to that in calponin 2-positive wild type cells, suggesting their correlated functions. With the close phylogenetic relationship between TAGLN and the calponin genes, SM22-alpha is identified as a calponin-like cytoskeleton regulatory protein. These findings laid a groundwork for understanding the physiological function of SM22-alpha in mechanoregulation of cytoskeleton and cell motility and its relationship with calponins.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
