Regulation and feedback in Fat/Dachsous signaling

巨大的果蝇原钙粘蛋白Fat和Dachsous（Ds）形成嗜异性的双向信号对 通过生长抑制Hippo途径调节增殖，平面细胞极性（PCP）通过 并且独立于“核心”PCP途径。这些功能由它们的哺乳动物同系物共享， Fat和Ds同源物的人类突变导致Hennekam的神经和多系统缺陷， 货车Maldergem综合征。尽管它的重要性，只有很少的人知道如何结合脂肪和 Ds改变细胞行为，从而改变它如何调节发育和病理。 脂肪、Ds以及Hippo和PCP途径的效应物集中在细胞的亚顶端区域。 上皮细胞，脂肪的细胞内结构域（ICD）对两个细胞的亚顶端水平有很强的影响， 关键蛋白质第一种是支架肌球蛋白Dachs，它结合并抑制疣（Lats 1/2），最后一种是支架肌球蛋白Dachs。 Hippo途径中的效应激酶，并调节核心PCP途径中的Sple。二是 FERM支架蛋白扩展，刺激疣活动。 通过结合蛋白质结合筛选、生物化学和分子遗传学， 通过DHHC棕榈酰转移酶从脂肪ICD到Dachs和扩展水平和定位 近似和它的目标之一，SH 3结构域蛋白Dlish。但是，近似值必须具有 另外的目标途径，以及近似和Dlish调控的细节知之甚少。 在本提案中，我们概述了确定新的近似目标的计划，包括扩展本身， 并进一步分析了近似活动和目标识别的规律，首先通过 修改近似及其目标，并通过先前未表征的GOLGA 7样 衔接蛋白CG 5447。 Fat和Ds还具有显著的能力，即通过其自身的细胞-细胞间作用使细胞沿着上皮平面移动。 细胞极化到相反的细胞面。我们已经开始了对细胞内控制和扩增的研究， Fat/Ds极化。我们探讨了以前未被怀疑的作用，细胞内途径的组成部分， 调节脂肪和Ds水平和极化，包括酪蛋白激酶1 β Dco，泛素连接酶Slim， 肌球蛋白Dachs和脂肪本身的细胞内结构域。

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.