Cloning and characterization of a novel gene, striamin, that interacts with the tumor suppressor protein p53

Expression analysis of a novel cDNA isolated from immortal murine fibroblasts revealed a single transcript of 3.0 kilobase pairs that was highly expressed in mouse and human striated muscle and in mouse heart. The gene has therefore been named striamin. Its expression was confined to skeletal muscle types with a fast glycolytic (2B) contractile phenotype. It was also detected in C2C12 mouse myoblasts and was down-regulated during in vitro myogenesis. The cDNA has a single open reading frame encoding a predicted 16.8-kDa protein of 149 amino acids with no homology to known proteins. Microinjection and transfection of green fluorescence protein-tagged striamin demonstrated that it localizes to the nucleus. Coimmunoprecipitations revealed that it can interact with p53 (a positive marker for myoblast differentiation) in vivo and in vitro. Furthermore, it repressed p53 activity in p53-mediated reporter assays. Fluorescence in situ hybridization with a mouse P1 genomic clone localized the gene to chromosome 12C3, which is syntenic to human chromosome 14q21-22.