Regulation and feedback in Fat/Dachsous signaling

巨大的果蝇原钙粘附素Fat和Dachsous(D)形成了一对异嗜性的双向信号对 它通过抑制生长的河马途径和平面细胞极性(PCP)来调节增殖，两者都是通过 并且不依赖于“核心”PCP途径。这些功能是由它们的哺乳动物同源物共享的，并且 人类脂肪和DS同源基因突变导致Hennekam和And的神经系统和多系统缺陷 范马尔德金综合征。尽管它很重要，但人们对脂肪和脂肪之间的结合知之甚少 DS改变了细胞的行为，从而改变了它调节发育和病理的方式。 脂肪、D和河马和PCP通路的效应器集中在 上皮细胞，而脂肪的胞内区(ICD)对两个细胞的亚尖水平有很强的影响 关键蛋白质。第一种是支架肌球蛋白达克斯，它结合并抑制疣(Lats1/2)，最后一种是 河马途径中的效应蛋白激酶，并调节核心PCP途径中的SPLe。第二个是 FERM支架蛋白膨胀，刺激疣活动。 利用蛋白质结合筛选、生物化学和分子遗传学的组合，我们建立了 通过DHHC棕榈酰转移酶实现从脂肪ICD到DACH的扩增水平和定位 它的靶标之一是SH3结构域蛋白Dlish。但是，近似值必须具有 该途径中的其他靶点，以及近似和Dlish调控的细节尚不清楚。 在这项提案中，我们概述了确定新的近似目标的特征的计划，包括扩展本身， 并进一步计划分析近似活动和目标识别的规则，首先通过 对近似和其目标的修饰，第二通过以前未描述的GOLGA7类 接头蛋白CG5447。 脂肪和D也是值得注意的能力，它们通过自己的细胞一一极化上皮面的细胞. 细胞极化到相反的细胞表面。我们已经开始了关于细胞内控制和扩增的研究 FAT/DS极化。我们探索了以前未知的作用，细胞内途径组件在 脂肪和DS水平和极化的调节，包括酪蛋白家族1DCO，泛素连接酶SLAMP， 肌球蛋白和脂肪本身的胞内结构域。

The giant Drosophila protocadherins Fat and Dachsous (Ds) form a heterophilic, bidirectional signaling pair that regulates proliferation via the growth-inhibiting Hippo pathway, and planar cell polarity (PCP) both through and independently of the “core” PCP pathway. These functions are shared by their mammalian homologs, and human mutations in Fat and Ds homologs cause the neurological and multisystem defects of Hennekam and Van Maldergem syndromes. Despite its importance, only a little is known about how binding between Fat and Ds change cell behavior, and thus how it regulates development and pathology. Fat, Ds and the effectors of the Hippo and PCP pathways are concentrated in the subapical domain of epithelial cells, and the intracellular domain (ICD) of Fat has strong effects on the subapical levels of two critical proteins. The first is the scaffolding myosin Dachs, which binds and inhibits Warts (Lats1/2), the final effector kinase in the Hippo pathway, and which regulates Sple in the core PCP pathway. The second is the FERM scaffolding protein Expanded, which stimulates Warts activity. Using a combination of protein-binding screens, biochemistry and molecular genetics, we established a link from the Fat ICD to Dachs and Expanded levels and localization via the DHHC palmitoyltransferase Approximated and one of its targets, the SH3 domain protein Dlish. However, Approximated must have additional targets in the pathway, and the details of Approximated and Dlish regulation are poorly understood. In this proposal we outline plans to identify characterize new Approximated targets, including Expanded itself, and further plans to analyze the regulation of Approximated activity and target recognition, first through modification of Approximated and its targets, and second through the previously uncharacterized GOLGA7-like adapter protein CG5447. Fat and Ds are also remarkable in their ability to polarize cells along the epithelial plane via their own cell-by- cell polarization to opposite cell faces. We have initiated studies on the intracellular control and amplification of Fat/Ds polarization. We explore previously unsuspected roles for intracellular pathway components in the regulation of Fat and Ds levels and polarization, including the casein kinse 1 Dco, the ubiquitin ligase Slimb, the myosin Dachs, and the intracellular domain of Fat itself.