DEVELOPMENTAL EXPRESSION OF THE MURINE SPLICEOSOME-ASSOCIATED PROTEINMSAP49

We have isolated the mouse homologue of human spliceosome-associated p rotein SAP49, mSAP49. mSAP49 contains two RNA recognition motifs (RRM) in the N terminus of the predicted amino acid sequence, and a highly basic C terminus rich in glycine/proline, mSAP49 displayed a plastic o f expression in cardiac development. In the adult mouse, mSAP49 is wid ely distributed, although it was found at relatively lower levels in t he heart, In situ hybridization analysis of mSAP49 mRNA distribution i n staged mouse embryos showed that mSAP49 onset occurs later in the he art than in other embryonic tissues. While mSAP49 expression was found at day 10.0 postconception (pc) in the optic eminence, optic vesicle, hindbrain, and somites, it was not in cardiac structures. mSAP49 was detected in the ventricles at day 11.5, and at day 13.5 it was also de tected in the atria, Northern analysis showed that mSAP49 mRNA display ed a peak of expression in the heart at days 14.0-15.0 pc, and its abu ndance decayed in the adult, This dynamic pattern of cardiac expressio n suggests that mSAP49 may be contributing to a change in the ratio of spliceosome components during cardiac growth and development, which m ay have consequences for tissue-specific splicing, RNA stabilization, or translation. (C) 1997 Wiley-Liss, Inc.