Analysis of molecular mechanism of muscular dystrophy involving skeletal muscle-specific calpain and connectin

骨骼肌特异性钙蛋白酶和连接蛋白参与肌营养不良的分子机制分析

基本信息

批准号：
09044208
负责人：
SUZUKI Koichi
金额：
$ 3.33万
依托单位：
Institute of Molecular and Cellular Biosciences, University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for international Scientific Research
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09044208/
关键词：
calpain connectin muscular dystrophy titin protease fodrin p94 カルバイン蛋白質分解筋肉筋ジストロフィー

项目摘要

Calpain is a typical intracellular Ca-dependent protease and hydrolyzes various cellular proteins in a limited manner, changes their properties, and known as a biomodulator. p94 is a calpain homologue expressed specifically in skeletal muscle. p94 is unique in having various properties distinct from ordinary ubiquitous calpains, e.g. autolyzes very rapidly apparently in the absence of Ca2+, binds to connectin in skeletal muscle at least at two specific sites, contains a nuclear translocation signal, has three insertion sequences, hydrolyzes fodrin, calpastatin, HSP6O, etc.Quite recently, p94 has been identified as a gene responsible for limb-girdle type 2A muscular dystrophy (LGMD2A). We selected 10 point mutants from various mutants found in LGMD2A patients and the point mutants were expressed in COS cells. Expressed p94 point mutants were examined for the unique properties listed above in order to identify which properties are directly correlated to LGMD2A.Binding to connectin and rapid autolysis showed no direct correlation to LGMD2A but a toss of proteolytic activity against fodrin, calpastatin, HSP6O resulted in LGMD2A Thus the next important issue is to identify a substrate(s) of p94 which directly or eventually activates degradation of muscle proteins and to clarify a mechanism for activation of muscle protein degradation. Studies are now in progress along this line.

钙蛋白酶是一种典型的细胞内Ca依赖性蛋白酶，以有限的方式水解各种细胞蛋白质，改变其性质，被称为生物调节剂。 p94 是一种在骨骼肌中特异性表达的钙蛋白酶同源物。 p94 的独特之处在于具有与普通普遍存在的钙蛋白酶不同的各种特性，例如显然，在没有 Ca2+ 的情况下，自溶速度非常快，至少在两个特定位点与骨骼肌中的连接蛋白结合，包含核易位信号，具有三个插入序列，水解 fodrin、calpastatin、HSP6O 等。最近，p94 已被鉴定作为导致肢带型 2A 型肌营养不良症 (LGMD2A) 的基因。我们从 LGMD2A 患者中发现的各种突变体中选择了 10 个点突变体，这些点突变体在 COS 细胞中表达。检查表达的 p94 点突变体的上述独特特性，以确定哪些特性与 LGMD2A 直接相关。与连接蛋白的结合和快速自溶显示与 LGMD2A 没有直接相关性，但针对 fodrin、calpastatin、HSP6O 的蛋白水解活性的折腾导致了LGMD2A 因此，下一个重要问题是鉴定直接或最终激活肌肉蛋白降解的 p94 底物，并阐明激活肌肉蛋白的机制。肌肉蛋白质降解。目前，相关研究正在进行中。