Expression of dystrophin-associated glycoproteins during human fetal muscle development: a preliminary immunocytochemical study.

An immunocytochemical study was performed on quadriceps muscle from eight fetuses ranging from 12 weeks of gestation to term, using antibodies against the dystrophin-associated proteins, in order to evaluate the developmental expression of these proteins. For comparison, antibodies against dystrophin and utrophin were also used. The expression of the 59 kDa dystrophin-associated protein was simultaneous with that of dystrophin, which is also a subsarcolemmal protein. The extracellular glycoprotein of 156 kDa (alpha-dystroglycan) and the transmembrane glycoprotein of 43 kDa (beta-dystroglycan) appeared to be expressed later. The transmembrane glycoproteins of 50 kDa (adhalin) and 35 kDa were fully expressed at an even later stage of fetal muscle development. This study suggests that the subsarcolemmal proteins may have an essential role in the assembly of the transmembrane and extracellular components of the dystrophin-glycoprotein complex during fetal muscle development. The knowledge obtained from observing the developmental expression of these proteins may contribute to the understanding of the molecular mechanism of their different involvement in muscle disorders.