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Characterization of membrane protein complex associated with dystrophin

与肌营养不良蛋白相关的膜蛋白复合物的表征

基本信息

批准号：
06454280
负责人：
SHIMIZU Teruo
金额：
$ 4.35万
依托单位：
Teikyo University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1996
项目状态：
已结题

项目摘要

In the present study, we have investigated the biological functions of the dystroglycan complex in the nervous system. As results, we show that the nervous system alpha-dystroglycan has a molecular mass of 120 kDa instead of 15kDa of that of muscle. The nervous system alpha-dystroglycan binds laminin with high affinity and this binding is dependent on calcium and is inhibited by heparin and NaCl. The nervous system alpha-dystroglycan is presumed to be associated with Dp116 and utrophin as anchoring proteins, but not the sarcoglycan complex. We also show that 120 kDa alpha-dystroglycan is a Schwann cell receptor of laminin-2, the endoneurial isoform of laminin comprised of the alpha2, beta1 and gamma1 chains, in the peripheral nervous system. Schwann cellalpha-dystroglycan is also a receptor of agrin, an acetylcholine receptor-aggregating molecule having partial homology to laminin alpha chains in the C-terminus. Immunochemical analysis demonstrates that the peripheral nerve isoform of agrin is a 400 kDa component of the endoneurial basal lamina and is co-localized with alpha-dystroglycan surrounding the outermost layr of myelin sheath of peripheral nerve fibers. Blot overlay analysis demonstrates that both endogenous peripheral nerve agrin and laminin-2 bind to Schwann cell alpha-dystroglycan. Recombinant C-terminal fragment of the peripheral nerve isoform of agrin also binds to Schwann cell alpha-dystroglycan, confirming that the binding site for Schwann cell alpha-dystroglycan resides in the C-terminus of agrinmolecule. Furthermore, the binding of recombinant agrin C-terminal fragment to Schwann cell alpha-dystroglycan competes with that of laminin-2. All together, these results indicate that alpha-dystroglycan is a dual receptor for agrin and laminin-2 in the Schwann cell membrane. Currently, we are investigating the biological functions of the dystroglycan complex in the central nervous system.

在本研究中，我们研究了糖异常复合物在神经系统中的生物学功能。结果表明，神经系统α -肌营养不良聚糖的分子质量为120 kDa，而不是肌肉的15kDa。神经系统α -三磷酸腺苷以高亲和力与层粘连蛋白结合，这种结合依赖于钙，并被肝素和NaCl抑制。神经系统α -糖营养不良被认为与Dp116和肌营养蛋白作为锚定蛋白有关，但与肌聚糖复合物无关。我们还表明，120 kDa α -肌营养不良聚糖是层粘连蛋白-2的雪旺细胞受体，层粘连蛋白-2是层粘连蛋白的神经内膜异构体，由α 2、β 1和γ 1链组成，存在于周围神经系统。雪旺细胞α -三磷酸甘聚糖也是agin的受体，agin是一种乙酰胆碱受体聚集分子，在c端与层粘连蛋白α链部分同源。免疫化学分析表明，agrin的外周神经异构体是神经内膜基底层的400 kDa成分，与周围外周神经纤维髓鞘最外层的α -糖酐共定位。印迹覆盖分析表明，内源性外周神经agrin和laminin-2都能与雪旺细胞α -不良聚糖结合。重组的agrin外周神经异构体的c端片段也能与雪旺细胞α -异糖甘氨酸结合，证实雪旺细胞α -异糖甘氨酸的结合位点位于agrin分子的c端。此外，重组agrin c -末端片段与雪旺细胞α -失调糖聚糖的结合与层粘连蛋白-2的结合竞争。综上所述，这些结果表明-三磷酸腺苷在雪旺细胞膜中是agrin和laminin-2的双重受体。目前，我们正在研究糖异常复合物在中枢神经系统中的生物学功能。