High impact information on Smpx

• We have isolated a murine cDNA encoding a 9-kD protein, Chisel (Csl), in a screen for transcriptional targets of the cardiac homeodomain factor Nkx2-5 [1].
• The small muscle-specific protein Csl modifies cell shape and promotes myocyte fusion in an insulin-like growth factor 1-dependent manner [1].
• However, ectopic expression in C2C12 myoblasts induced formation of lamellipodia in which Csl protein became tethered to membrane ruffles [1].
• Csl transcripts were detected in atria and ventricles of the heart and in all skeletal muscles and smooth muscles of the stomach and pulmonary veins [1].
• Csl protein was distributed throughout the cytoplasm in fetal muscles, although costameric and M-line localization to the muscle cytoskeleton became obvious after further maturation [1].

Biological context of Smpx

• The murine X-linked gene Chisel (Csl/Smpx) encodes a 9-kDa protein that associates in heart and skeletal muscle cells with the costameric cytoskeleton, implicated in maintaining muscle integrity and responses to biomechanical stress [2].
• Targeted disruption of Csl showed no overt muscle phenotype [1].

Anatomical context of Smpx

• MYC-Csl induced cell spreading and lamellipodia formation in C2C12 cells at the expense of filopodia, suggestive of modulation of Rac1 activity [2].

Physical interactions of Smpx

• Csl could be co-immunoprecipitated with vinculin from extracts of C2C12 cells and native muscle [2].

References