Goudenege Sébastien, Dargelos Elise, Claverol Stéphane, Bonneu Marc, Cottin Patrick, Poussard Sylvie
Université Bordeaux I, USC-INRA 2009, Unité Protéolyse, Croissance et Développement Musculaire, ISTAB, Talence, France.
Proteomics. 2007 Sep;7(18):3289-98. doi: 10.1002/pmic.200700124.
Caveolae are specialised RAFTs (detergent-resistant membrane microdomains enriched in cholesterol and glycosphingolipids). Caveolin, the main caveolae protein, is essential to the organisation of proteins and lipids, and interacts with numerous mediating proteins through a 'Caveolin Scalfolding Domain'. Consequently, caveolae play a major role in signal transduction and appear to be veritable signalling platforms. In muscle cells, caveolae are essential for fusion and differentiation, and are also implicated in a type of muscular dystrophy (LGMD1C). In a preceding work, we demonstrated the presence of active milli-calpain (m-calpain) in myotube caveolae. Calpains are calcium-dependent proteases involved in several cellular processes, including myoblast fusion and migration, PKC-mediated intracellular signalling and remodelling of the cytoskeleton. For the first time, we have proved the cholesterol-dependent localisation of m-calpain in the caveolae of C(2)C(12) myotubes. Calpain-dependent caveolae involvement in myoblast fusion was also strongly suggested. Furthermore, eight differentially expressed caveolae associated proteins were identified by 2-DE and LC-MS/MS analyses using an m-calpain antisense strategy. This proteomic study also demonstrates the action of m-calpain on vimentin, desmin and vinculin in myotube caveolae and suggests m-calpain's role in several mitochondrial pathways.
小窝是特殊的筏（富含胆固醇和糖鞘脂的抗去污剂膜微区）。小窝蛋白是小窝的主要蛋白质，对蛋白质和脂质的组织至关重要，并通过“小窝蛋白支架结构域”与众多介导蛋白相互作用。因此，小窝在信号转导中起主要作用，似乎是名副其实的信号平台。在肌肉细胞中，小窝对融合和分化至关重要，也与一种肌肉营养不良症（LGMD1C）有关。在之前的一项工作中，我们证明了肌管小窝中存在活性微摩尔钙蛋白酶（m-钙蛋白酶）。钙蛋白酶是钙依赖性蛋白酶，参与多种细胞过程，包括成肌细胞融合和迁移、PKC介导的细胞内信号传导以及细胞骨架重塑。我们首次证明了m-钙蛋白酶在C(2)C(12)肌管小窝中的胆固醇依赖性定位。也强烈提示了钙蛋白酶依赖性小窝参与成肌细胞融合。此外，使用m-钙蛋白酶反义策略通过二维电泳（2-DE）和液相色谱-串联质谱（LC-MS/MS）分析鉴定了8种差异表达的小窝相关蛋白。这项蛋白质组学研究还证明了m-钙蛋白酶对肌管小窝中波形蛋白、结蛋白和纽蛋白的作用，并提示m-钙蛋白酶在几种线粒体途径中的作用。
