Skeletal Muscles of Transgenic Mice Expressing Human snoN, a Homologue of c-ski

Abstract

The sno (ski-related novel) gene, was originally identified as a homologue of cellular proto-oncogene, c-ski. Ski and SnoN are localized in the nucleus and probably act as transcriptional factors, although their functions have not yet been fully elucidated. In an attempt to identify a role of snoN in vivo, we produced 4 transgenic mice, harboring human snoN (hsnoN) cDNA driven by the simian virus 40 (SV40) enhancer/promoter. One of the transgenic mice (#11-4) exhibited retarded growth, and the hsnoN expression was confirmed in heart, stomach, skeletal muscles and kidney. Another transgenic mouse (#9-3), on the other hand, did not show any obvious phenotypic alteration except sterility, although hsnoN expression was detected in the soleus and the plantaris muscles, where the endogenous snoN expression was not observed. While the soleus of normal mice contains much higher proportion of type I fibers (high ATPase activity) than type II fibers (low ATPase activity), in the #9-3 mouse the soleus was smaller, and contained reduced number of type I fibers, compared to normal mice. It is suggested that snoN might play a role in the differentiation of type I muscle fibers.