Dystroglycan mRNA expression during normal and mdx mouse embryogenesis: A comparison with utrophin and the apo‐dystrophins

Abstract

ABSTRACT(Y dystroglycan (156 kDa DAG) and p dystroglycan (43 kDa DAG) are encoded by the same gene and are components of the dystrophin-associated membrane glycoprotein complex. The dystroglycans together with dystrophin form a link between the extracellular matrix and the intracellular 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 tube and brain. The expression patterns of dystroglycan and dystrophin overlap in the major muscle systems during development, suggesting that the dystrophin-dystroglycan complex plays an important role during myogenesis. In contrast, the major sites of utrophin expression do not co-localize with those of dystroglycan suggesting that utrophin may interact with a distinct membrane-associated complex in these non-muscle sites. In m h embryos the pattern of distribution of dystroglycan mRNA remains unchanged, as do those of utrophin and apo-dystrophin mRNAs. This observation implies that the observed changes in the relative abundance of DAGs and utrophin in dystrophin-deficient muscle occur post-transcriptionally. 0 1995 Wiley-Liss, Inc.

Distinct α7Aβ1 and α7Bβ1 integrin expression patterns during mouse development: α7A is restricted to skeletal muscle but α7B is expressed in striated muscle, vasculature, and nervous system

“…The a 7 A probe and (Y7B antibodies reacted with all visible skeletal muscles at El6 and at the later stages of development. Dystroglycan mRNA was present in both primary and secondary muscle fibers as has been reported previously (Schofield et al, 1995). Closer inspection of the distribution of staining in muscle revealed the concentration at myotendinous junctions and at the sarcolemma of the secondary myotubes (Fig.…”

Evidence of an Agrin Receptor in Cortical Neurons

“…Although this now seems doubtful (Sugiyama et al, 1994;Bowen et al, 1996), evidence suggests that dystroglycan is involved at some level in the AChR-clustering pathway (Jacobson et al, 1998). Dystroglycan is also expressed in brain (Górecki et al, 1994;Schofield et al, 1995), and some of the biochemical characteristics of agrin induction of c-fos are consistent with the possibility that it might be the putative neuronal receptor for agrin. Several lines of evidence, however, make this unlikely.…”

Muscular dystrophy begins early in embryonic development deriving from stem cell loss and disrupted skeletal muscle formation

“…In E13.5-E17.5 mdx embryos, we found, on average, a 3-5-fold excess of caveolin-3 (depending on the embryonic stage), suggesting that disruption of caveolin-3 expression is an early and significant consequence of dystrophin deficiency. Embryonic mRNA expression patterns of dystrophin, but not utrophin, overlap those of dystroglycan in WT embryos and this pattern is unchanged in mdx embryos (Houzelstein et al, 1992;Schofield et al, 1995). Therefore, dystrophin may negatively regulate caveolin-3 by competitive binding to β-dystroglycan (Ilsley et al, 2002).…”