| Co-Investigator(Kenkyū-buntansha) |
YAMAMOTO Hideko National Institute of Neuroscience National Center of Neurology and Psychiatry D, 機能研究部, 流動研究員
MIZUNO Yuji National Institute of Neuroscience National Center of Neurology and Psychiatry D, 機能研究部, 流動研究員
SUZUKI Atsushi National Institute of Neuroscience National Center of Neurology and Psychiatry D, 機能研究部, 併任研究員
HAGIWARA Yasuko National Institute of Neuroscience National Center of Neurology and Psychiatry D, 機能研究部, 室長 (00175530)
YOSHIDA Mikiharu National Institute of Neuroscience National Center of Neurology and Psychiatry D, 機能研究部, 室長 (70111151)
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| Research Abstract |
Dystrophin is the responsible protein of Duchenne muscular dystrophy (DMD). We purified dystrophin and its associated proteins, raised their antibodies and studied the molecular pathophysiology of DMD in terms of these proteins.
Dystrophin purified from rabbit skeletal muscles carries several kinds of proteins, some of which are glycoproteins. We determined the molar ratio of these binding proteins to dystrophin. We digested dystrophin with calpain to analyze its enzyme-accessible sites.
Among the dystrophin binding proteins, glycoproteins A2, A3 and A4 have been reported forming a complex called glycoprotein complex (GPC). We found that GPC bound to the cysteine-rich domain and the first half of the C-terminal domain of dystrophin. This site has been reported, when missing, to give rise to sever phenotype of the disease, namely, DMD. On these basis, we conclude that the loss of interaction between dystrophin and GPC. The amino acid sequence of GPC binding site is highly homologous to that of corresponding site of utrophin, an isoform of dystorphin. Therefore, it is highly possible that GPC can bind also to utrophin at the corresponding site.
Further, we examined DMD muscles histochemically and with immunoblot analysis, and found that utrophin was fairly heavily expressed in place of dystrophin which was missing, A2 and A3 were reduced but distinctly present. This show keen contrast to the reports of Campbell's group. Based on our results, we tentatively conclude that utrophin is expressed to replace in DMD muscles, and binds to GPC but the disease progressed probably due to its low abundance of expression.
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