ADAM 12 DISINTEGRIN DOMAIN AND MYOBLAST FUSION

成肌细胞融合对骨骼肌的发育和修复至关重要 损伤或退化后。 虽然有很多因素 与成肌细胞融合有关，这种融合的确切机制 过程仍然未知。 更好地理解分子事件 因此，在计划之前， 旨在增强肌肉修复或优化基因疗法的策略 使用成肌细胞作为载体将靶向基因递送到疾病中 肌肉. 在拟议的研究中，我们将调查ADAM 12的作用， ADAM家族蛋白质（含有去整合素和 金属蛋白酶结构域）在成肌细胞融合中的作用。 我们假设 ADAM 12的去整合素结构域与成肌细胞中的整合素受体结合 膜和ADAM整合素相互作用提供了一种机制， 成肌细胞的自我识别导致融合 我们的长期目标是 将这些研究扩展到ADAM 12的其他领域， 对ADAM 12在成肌细胞中功能的全面认识 沟通与融合。 首先，我们将研究是否ADAM 12的同源区域， 与可溶性去整合素结合构成自主蛋白质结构域， 一种执行独特生化功能的潜力。 那就 从成肌细胞质膜鉴定可与 去整合素结构域。 使用定点突变，我们将 确定哪些残基和结构特征的 去整合素结构域是相互作用的关键。 如果新 确定的受体属于整合素家族，我们将研究 如果去整合素的结合触发任何已知的整合素信号传导 途径。 最后，我们将评估去整合素的重要性- 通过研究封闭的影响， 或消除ADAM的去整合素结构域之间的相互作用 12和它的受体。

Myoblast fusion is essential for skeletal muscle development and repair following injury or degeneration. Although a number of factors have been implicated in myoblast fusion, the precise mechanism of this process remains unknown. A better understanding of the molecular events associated with fusion is, therefore, required before one can plan strategies aimed to enhance muscle repair or to optimize gene therapies employing myoblasts as vehicles for targeted gene delivery into diseased muscle. In the proposed studies, we will investigate a role of ADAM 12, a member of the ADAM family of proteins (containing A Disintegrin And Metalloprotease domain) in myoblast fusion. We hypothesize that the disintegrin domain of ADAM 12 binds to an integrin receptor in myoblast membrane and that ADAM-integrin interactions provide a mechanism of myoblast self-recognition that leads to fusion. Our long-term goal is to extend these studies to other domains of ADAM 12 and to obtain a comprehensive understanding of ADAM 12 function in myoblast communication and fusion. First, we will investigate if the region of ADAM 12 that is homologous to soluble disintegrins constitutes an autonomous protein domain and has a potential to execute a distinct biochemical function. Then, we will identify a receptor from myoblast plasma membrane that can interact with the disintegrin domain. Using site-directed mutagenesis, we will determine what residues and what structural signatures of the disintegrin domain are critical for the interactions. If the newly identified receptor belongs to the integrin family, we will investigate if binding of disintegrin triggers any of the known integrin signaling pathways. Finally, we will evaluate the importance of the disintegrin- mediated adhesion in myoblast fusion by studying the effects of blocking or eliminating the interactions between the disintegrin domain of ADAM 12 and its receptor.