Regulation of Hippo signaling and planar cell polarity via distinct regions of the Fat intracellular domain

The large Drosophila protocadherin Fat (Ft) is a receptor for signal transduction pathways that control growth (Hippo signaling), planar cell polarity (PCP), metabolism and the proximodistal patterning of appendages. The intracellular domain (ICD) of Ft is crucial in implementing its biological functions. Six regions of high conservation (named A-F) within the ICD have been identified, as well as distinct regions mediating Hippo pathway activity that have been functionally characterized via overexpression assays. Here, we make targeted deletions of these highly conserved residues and the putative Hippo- and PCP-regulating domains of endogenous Ft using CRISPR/Cas9. Through transcriptomic, developmental, and phenotypic analyses, we show that different regions of Ft contribute uniquely to chromatin dynamics, tissue morphogenesis, PCP and metabolic regulation. We also demonstrate that different regions of Ft regulate Yorkie activity in opposite directions, finely tuning growth and tissue development. Strikingly, conserved regions D and F are key regulators of Ft’s functions- exhibiting opposing effects on wing morphology and Hippo pathway modulation- and conserved region D is the main regulator of PCP. RNA-seq profiling of imaginal wing discs from third-instar Drosophila larvae. This dataset is used to compare wild-type, fat nulls, conserved and functional domain mutants

大型果蝇原钙粘蛋白Fat（Ft）是调控生长（Hippo信号通路）、平面细胞极性（PCP）、代谢以及附肢近-远模式形成的信号转导通路的受体。Ft的细胞内结构域（intracellular domain, ICD）在执行其生物学功能中发挥关键作用。研究人员已在ICD中鉴定出6个高度保守的区域（命名为A至F），同时还发现了介导Hippo通路活性的不同区域，这些区域通过过表达实验完成了功能表征。本研究利用CRISPR/Cas9技术，对内源Ft的上述高度保守残基以及推定的Hippo和PCP调控结构域进行了靶向缺失操作。通过转录组学、发育生物学及表型分析，我们证实Ft的不同区域对染色质动态调控、组织形态发生、PCP以及代谢调控具有独特的贡献。我们还证实，Ft的不同区域可通过相反的方向调控Yorkie的活性，从而精细调控生长与组织发育。值得注意的是，保守区域D与F是Ft功能的关键调控因子——它们对翅膀形态发生及Hippo通路调控具有相反的作用——且保守区域D是PCP的主要调控因子。本数据集源自三龄果蝇幼虫的翅成虫盘转录组RNA测序分析，用于对比野生型、fat无效突变体（fat nulls）以及保守结构域与功能结构域突变体的转录组差异。