College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China;
Beijing Key Laboratory of Biodiversity and Organic Farming, Beijing 100193, China.
Proc Natl Acad Sci U S A. 2019 Jan 22;116(4):1319-1324. doi: 10.1073/pnas.1811891116. Epub 2019 Jan 3.
The protocadherin Fat controls organ size through the Hippo pathway, but the biochemical links to the Hippo pathway components are still poorly defined. We previously identified Dlish, an SH3 domain protein that physically interacts with Fat and the type XX myosin Dachs, and showed that Fat's regulation of Dlish levels and activity helps limit Dachs-mediated inhibition of Hippo pathway activity. We here characterize a parallel growth control pathway downstream of Fat and Dlish. Using immunoprecipitation and mass spectrometry to search for Dlish partners, we find that Dlish binds the FERM domain growth repressor Expanded (Ex); Dlish SH3 domains directly bind sites in the Ex C terminus. We further show that, in vivo, Dlish reduces the subapical accumulation of Ex, and that loss of Dlish blocks the destabilization of Ex caused by loss of Fat. Moreover, Dlish can bind the F-box E3 ubiquitin ligase Slimb and promote Slimb-mediated ubiquitination of Expanded in vitro. Both the in vitro and in vivo effects of Dlish on Ex require Slimb, strongly suggesting that Dlish destabilizes Ex by helping recruit Slimb-containing E3 ubiquitin ligase complexes to Ex.
原钙黏蛋白 Fat 通过 Hippo 通路控制器官大小，但与 Hippo 通路成分的生化联系仍未得到很好的定义。我们之前鉴定出 Dlish，一种与 Fat 和 XX 型肌球蛋白 Dachs 相互作用的 SH3 结构域蛋白，并表明 Fat 对 Dlish 水平和活性的调节有助于限制 Dachs 介导的 Hippo 通路活性抑制。我们在这里描述了 Fat 和 Dlish 下游的平行生长控制通路。我们使用免疫沉淀和质谱法来搜索 Dlish 的伴侣，发现 Dlish 与 FERM 结构域生长抑制因子 Expanded（Ex）结合；Dlish SH3 结构域直接结合 Ex C 末端的位点。我们进一步表明，在体内，Dlish 减少了 Ex 的亚顶积累，并且 Dlish 的缺失阻止了 Fat 缺失引起的 Ex 不稳定。此外，Dlish 可以结合 F-box E3 泛素连接酶 Slimb，并促进体外 Slimb 介导的 Expanded 泛素化。Dlish 对 Ex 的体外和体内作用都需要 Slimb，这强烈表明 Dlish 通过帮助招募含有 Slimb 的 E3 泛素连接酶复合物到 Ex 上来稳定 Ex。
