DYSTROGLYCAN MESSENGER-RNA EXPRESSION DURING NORMAL AND MDX MOUSE EMBRYOGENESIS - A COMPARISON WITH UTROPHIN AND THE APO-DYSTROPHINS

alpha dystroglycan (156 kDa DAG) and beta dystroglycan (43 kDa DAG) ar e encoded by the same gene and are components of the dystrophin-associ ated membrane glycoprotein complex. The dystroglycans together with dy strophin form a link between the extracellular matrix and the intracel lular cytoskeleton of the muscle fibre. Using in situ hybridisation to mRNA in embryo sections we have examined the expression of the mouse dystroglycan gene. Dystroglycan transcripts are ubiquitously expressed throughout development but are most abundant in cardiac, skeletal and smooth muscle and in ependymal cells lining the developing neural tub e and brain. The expression patterns of dystroglycan and dystrophin ov erlap in the major muscle systems during development, suggesting that the dystrophin-dystroglycan complex plays an important role during myo genesis. In contrast, the major sites of utrophin expression do not co -localize with those of dystroglycan suggesting that utrophin may inte ract with a distinct membrane-associated complex in these non-muscle s ites, In mdx embryos the pattern of distribution of dystroglycan mRNA remains unchanged, as do those of utrophin and apo-dystrophin mRNAs. T his observation implies that the observed changes in the relative abun dance of DAGs and utrophin in dystrophin-deficient muscle occur post-t ranscriptionally. (C) 1995 Wiley-Liss, Inc.