Dystrophin‐related protein is found in the central nervous system of mice at various developmental stages, especially at the postsynaptic membrane

Dystrophin deficiency is known to be the cause of X-linked Duchenne muscular dystrophy (DMD). A recently cloned B3-cDNA shares 80% homology with the C-terminus and actin-binding portion of dystrophin. This autosome-derived gene product is called dystrophin-related protein (DRP). DRP is known to exist in fetal muscles even in mdx mice, an animal model for X-linked DMD, but not in mature mouse muscles. We raised a polyclonal antibody against a B3-unique amino acid sequence (Ab-LDP) and investigated the existence and distribution of DRP in the central nervous system (CNS) tissues of (mdx) and normal control B10 mice at various stages of development using immunoblotting and immunohistochemical methods. The former shows that DRP exists in the CNS of both B10 and mdx mice, regardless of the developmental stage, with the exception that the 420 kDa DRP band of the 15-day fetus is faint. In immunohistochemical studies, the choroid plexus, some neurons, glial cells, pia mater, and blood vessels were stained with Ab-LDP. Staining intensity did not differ between B10 and mdx mice of between developmental stages except that the 15-day fetus stained only faintly. This is in contrast of the results obtained for muscles in which DRP localized to muscle membrane in embryo decreases and is assembled at the neuromuscular junction in adults. In addition, an electron microscopic study on the cerebral cortex from adult B10 mice was also performed and revealed Ab-LDP staining of the postsynaptic membrane of dendrite and the rough endoplasmic reticulum of neurons. This is a new finding and is of interest because DRP is expressed at the neuromuscular junction and its localization is similar to that of the acetylcholine receptor. Wiley-Liss, Inc.