Control of tissue growth and architecture by Drosophila Tsg101

描述（由申请人提供）：顶基极性因子的表达改变与脊椎动物的癌症和模型无脊椎动物的组织过度生长有关，但这些因子影响生长调节途径的机制尚未明确。我们以前已经确定了果蝇基因tsg 101（肿瘤易感基因-101）作为一个因素，需要同时保持组织极性和抑制肿瘤样过度生长的幼虫成虫盘，这是简单的上皮器官，引起大多数成年人的结构。我们已经表明，损失tsg 101块内溶酶体营业额的关键顶端膜决定因素Crumbs，这过量的Crumbs蛋白积累在顶端膜，异位扩散到基底外侧膜，并积累在晚期内体。由于Crumbs使与Par/aPKC和Scribble/Dlg极性复合物物理和功能相互作用的顶端膜相关复合物成核，Crumbs调节中的这些缺陷提供了tsg 101损失对上皮极性和结构的影响的现成解释。 值得注意的是，过表达的Crumbs也驱动大量的胚盘过度生长，表明这种极性因子在tsg 101细胞中具有第二种更直接的致癌作用。在已发表的工作中，我们发现Crumbs的胞质尾区包含一个以前未被识别的生长调节基序，通过该基序，它与扩展蛋白相互作用并调节扩展蛋白，扩展蛋白是保守的Hippo/Mst 2肿瘤抑制途径的关键组成部分。这些数据表明，Crumbs是一种多功能蛋白质，能够整合连接极性信号与完善的Hippo/Mst 2生长调节途径，并且那些破坏Crumbs运输和定位的病变可能对该途径的活性具有非常直接的影响。 我们在这项提案中的目标是测试这个新发现的Crumbs-Hpo/Mst 2链接在tsg 101突变肿瘤过度生长中的作用，并从我们已确定为Crumbs驱动椎间盘过度生长的显性修饰剂的一小部分突变中鉴定Crumbs-Hpo/Mst 2通路的新组分。 特别是，我们将集中我们的分析对泰曼基因，它编码的苍蝇同源物的人扩增乳腺癌-1（AIB-1）癌基因，我们认为作为一个转录辅激活因子的Crumbs-Hpo/Mst 2途径。我们将在果蝇器官和培养细胞中使用标准的遗传和分子技术来进行拟议的研究。

DESCRIPTION (provided by applicant): Altered expression of apicobasal polarity factors is associated with cancer in vertebrates and tissue overgrowth in model invertebrates, yet mechanisms by which these factors affect growth regulatory pathways are not well defined. We have previously identified the Drosophila melanogaster gene tsg101 (tumor susceptibility gene-101) as a factor that is required to simultaneously maintain tissue polarity and suppress tumor-like overgrowth of the larval imaginal discs, which are simple epithelial organs that give rise to most adult structures. We have shown that loss of tsg101 blocks endolysosomal turnover of the key apical membrane determinant Crumbs, and that this excess Crumbs protein accumulates at the apical membrane, spreads ectopically onto the basolateral membrane, and accumulates in late endosomes. As Crumbs nucleates an apical membrane- associated complex that interacts physically and functionally with the Par/aPKC and Scribble/Dlg polarity complexes, these defects in Crumbs regulation provide a ready explanation of the effect of tsg101 loss on epithelial polarity and architecture. Notably, over expressed Crumbs also drives substantial imaginal disc overgrowth, suggesting that this polarity factor has a second, more direct oncogenic role in tsg101 cells. In published work, we have found that the cytoplasmic tail of Crumbs contains a previously unrecognized growth-regulatory motif through which it interacts with and regulates the expanded protein, which is a key component of the conserved Hippo/Mst2 tumor suppressor pathway. These data show that Crumbs is a multi-functional protein capable of integrating junctional polarity signals with the well-established Hippo/Mst2 growth-regulatory pathway, and those lesions that disrupt Crumbs trafficking and localization may have very direct effects on the activity of this pathway. Our objectives in this proposal are to test the role of this newly discovered Crumbs-Hpo/Mst2 link in the excessive growth of tsg101 mutant tumors, and to identify novel components of the Crumbs-Hpo/Mst2 pathway from among a small collection of mutations we have identified as dominant-modifiers of Crumbs driven disc overgrowth. In particular, we will focus our analysis on the taiman gene, which encodes the fly homolog of the human Amplified in Breast Cancer-1 (AIB-1) oncogene, and that we believe acts as a transcriptional coactivator for the Crumbs-Hpo/Mst2 pathway. We will use standard genetic and molecular techniques in Drosophila organs and cultured cells to carry out the proposed studies.