Analysis of the cell adhesion molecule sticks-and-stones reveals multiple redundant functional domains, protein-interaction motifs and phosphorylated tyrosines that direct myoblast fusion in Drosophila melanogaster
Analysis of the cell adhesion molecule sticks-and-stones reveals multiple redundant functional domains, protein-interaction motifs and phosphorylated tyrosines that direct myoblast fusion in Drosophila melanogaster
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DOI：
10.1534/genetics.107.083808
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发表时间：
2008-03-01
期刊：
影响因子：
3.3
通讯作者：
Abmayr, Susan M.
中科院分区：
文献类型：
--
作者：
Kocherlakota, Kiranmai S.;Wu, Jian-Min;Abmayr, Susan M.
黑腹果蝇（Drosophilamnelanogaster）幼虫体壁肌细胞由创始成肌细胞（founder myoblasts，FM）和融合成肌细胞（fusion-competent myoblasts，FCM）融合形成。Sticks-and-Stones（SNS）在所有FCM的表面上表达，并介导与FM的粘附和发育中的合胞体。然后，成肌细胞融合所必需的细胞内成分被募集到这些粘附接触中。在本文的研究中，使用GAL 4/UAS系统对SNS细胞结构域进行功能分析，鉴定了指导成肌细胞融合的序列，推测是通过募集这些细胞内组分。一系列广泛的缺失和定点突变的能力，以挽救sns突变胚胎的成肌细胞融合缺陷进行了评估。缺失研究揭示了SNS中的冗余功能域。令人惊讶的是，用于结合突触后密度-95/盘大/含闭锁小带-1-结构域（PDZ）蛋白质的高度保守的共有位点具有高的磷酸化概率，在成肌细胞融合中没有显著作用。生物化学研究证实，SNS胞内结构域在多个酪氨酸处磷酸化，并且它们的定点突变损害了相应转基因拯救成肌细胞融合的能力。类似的诱变揭示了保守的脯氨酸丰富的区域的要求。SNS胞质结构域内多个关键序列的这种复杂性和冗余性表明它通过复杂的相互作用发挥作用，所述相互作用可能包括磷酸酪氨酸结合蛋白和含SH 3结构域的蛋白。
The larval body wall muscles of Drosophila rnelanogaster arise h), fusion of founder myoblasts (FMs) and fusion-competent myoblasts (FCMs). Sticks-and-Stones (SNS) is expressed on the surface of all FCMs and mediates adhesion with FMs and developing syncytia. Intracellular components essential for myoblast fusion are then recruited to these adhesive contacts. In the studies herein, a functional analysis of the SNS cytodomain using the GAL4/UAS system identified sequences that direct myoblast fusion, presumably through recruitment of these intracellular components. An extensive series of deletion and site-directed mutations were evaluated for their ability to rescue the myoblast fusion defects of sns mutant embryos. Deletion studies revealed redundant Functional domains within SNS. Surprisingly, highly conserved consensus sites for binding post-synaptic density-95/discs large/zonula occludens-l-domain-containing (PDZ) proteins mid serines With a high probability of phosphorylation play no significant role in myoblast fusion. Biochemical studies establish that the SNS cytodomain is phosphorylated at multiple tyrosines and their site-directed mutagenesis compromises the ability of the corresponding transgenes to rescue myoblast fusion. Similar mutagenesis revealed a requirement for conserved proline-rich regions. This complexity and redundancy of multiple critical sequences within the SNS cytodomain suggest chat it functions through a complex array oh interactions that likely includes both phosphotyrosine-binding and SH3-domain-containing proteins.