CLONING OF THE GENES ENCODING MOUSE CARDIAC AND SKELETAL CALSEQUESTRINS - EXPRESSION PATTERN DURING EMBRYOGENESIS

Calsequestrin is a low-affinity and high-capacity calcium binding prot ein in the sarcoplasmic reticulum (SR). In the present study, we have cloned and sequenced mouse cardiac and skeletal calsequestrin cDNAs. T he deduced amino acid sequences are highly homologous to those of othe r mammalian calsequestrins. As expected, the cardiac and skeletal cals equestrins are expressed specifically and exclusively in adult heart a nd skeletal muscles, respectively. In situ hybridization was performed to examine the expression pattern of the calsequestrins in the develo ping mouse and rat embryos. During early organogenesis, the cardiac an d skeletal calsequestrin transcripts were detected exclusively in the heart primordium and the myotome of somites, respectively. The cardiac calsequestrin transcripts were later detected in fetal heart and skel etal muscles, whereas the skeletal calsequestrin transcripts were only found in fetal skeletal muscles. These data suggest that the cardiac calsequestrin plays a role in the differentiation and function of hear t, and in the function of fetal skeletal muscles in conjunction with t he skeletal calsequestrin, but not in the early differentiation of the myotome of somites. The expression of the skeletal calsequestrin in t he myotome is regulated probably by myogenin, a myogenic regulatory ge ne. (C) 1998 Elsevier Science B.V. All rights reserved.