Elucidation of Molecular Mechanism of Muscle Degenaration using Developmental Biology Technique and development of therapeutics

层粘连蛋白2（Laminin-2，merosin）是骨骼肌基膜的主要成分，由α2、β1和γ1三条链组成。层粘连蛋白α2链基因的突变导致裂殖蛋白缺陷型先天性肌营养不良症（MD-CMD）。层粘连蛋白2（Laminin-2，merosin）是骨骼肌基膜的主要成分，由α2、β1和γ1三条链组成。层粘连蛋白α2链基因的突变导致裂殖蛋白缺陷型先天性肌营养不良症（MD-CMD）。为了阐明MD-CMD的分子病理学，我们产生了层粘连蛋白α2链敲除小鼠（dy<3K>），其中层粘连蛋白α2链的表达完全缺失。结果<3K>表明，该小鼠具有典型的肌营养不良表型，是目前公认的MD-CMD的理想模型。我们精确地记录了dy^ /dy^小鼠肌肉的形态学变化<3K><3K>。生后第9天（P9）有少量纤维坏死，而P10则有大量纤维坏死。在这个阶段，伊文思蓝染料IgG内流到肌纤维沿着肌纤维的坏死变化。P11有部分纤维再生，P13有大量再生纤维。在此阶段，在Manyu再生纤维中发现canpase-3抑制和TUNEL阳性的肌细胞核。Bad的去磷酸化也被检测到，其触发凋亡信号级联，这表明层粘连蛋白α2链的缺失通过中断来自细胞外基质的存活信号而导致早期再生纤维的凋亡。再生过程不完全或失败。小鼠外周神经系统髓鞘形成不完全，免疫系统发育异常。

Laminin-2(merosin), composed of α2, β1 and γ1 chains, is a major comnponent of skeletal muscle basal lamina. Murarions of the laminin α2 chain gene cause merosin-deficient congenital muscular dystrophy(MD-CMD). To clarify the molecular pathology ofLaminin-2(merosin), composed of α2, β1 and γ1 chains, is a major comnponent of skeletal muscle basal lamina. Murarions of the laminin α2 chain gene cause merosin-deficient congenital muscular dystrophy(MD-CMD). To clarify the molecular pathology of MD-CMD, we generated lamininarufα2 chain knock out mouse(dy^<3K>), where the expression of laminin α2 chain is completely absent. The dy^<3K>revealed typical phenotype of muscular dystrophy, therefore the mouse is accepted as an ideal model of MD-CMD at date. We precisely ezamined morphological changes of the sleletal muscle of dy^<3K>/dy^<3K>mice. On postnatal day 9(P9) a few fibers showed necrotic changes, but on P10 manuy necrotic fibers were seen. In this stage, Evans Blue dye IgG influx into muscle fibers were found along necrotic changes of muscle fibers. Several fibers began to regenerate on P11, nad numerous regenerating fibers appeared on P13. In this stage, canpase-3 antivation and TUNEL-posotive myonuclei were found in manyu regeneratin fibers. Dephosphorylation of Bad, which triggers apoptotic signaling cascade, was also detected, suggesting that the absence of laminin α2 chain results in apoptosis of early regfenerating fibers through the interruption of survival signal from the extracellular matrix. Imcomplete or abortive regenarating process. The mouse also showed incomplete myelination in peripheral nervous system and maturational abnomality in the immunne system.