Mistry Hemlata, Wilson Beth A, Roberts Ian J H, O'Kane Cahir J, Skeath James B
Department of Genetics, Washington University School of Medicine, 4566 Scott Avenue Box 8232, St Louis, MO 63110, USA.
Mech Dev. 2004 Dec;121(12):1495-507. doi: 10.1016/j.mod.2004.07.007.
Ubiquitin-mediated proteolysis regulates the steady-state abundance of proteins and controls cellular homoeostasis by abrupt elimination of key effector proteins. A multienzyme system targets proteins for destruction through the covalent attachment of a multiubiquitin chain. The specificity and timing of protein ubiquitination is controlled by ubiquitin ligases, such as the Skp1-Cullin-F box protein complex. Cullins are major components of SCF complexes, and have been implicated in degradation of key regulatory molecules including Cyclin E, beta-catenin and Cubitus interruptus. Here, we describe the genetic identification and molecular characterisation of the Drosophila Cullin-3 homologue. Perturbation of Cullin-3 function has pleiotropic effects during development, including defects in external sensory organ development, pattern formation and cell growth and survival. Loss or overexpression of Cullin-3 causes an increase or decrease, respectively, in external sensory organ formation, implicating Cullin-3 function in regulating the commitment of cells to the neural fate. We also find that Cullin-3 function modulates Hedgehog signalling by regulating the stability of full-length Cubitus interruptus (Ci155). Loss of Cullin-3 function in eye discs but not other imaginal discs promotes cell-autonomous accumulation of Ci155. Conversely, overexpression of Cullin-3 results in a cell-autonomous stabilisation of Ci155 in wing, haltere and leg, but not eye, imaginal discs suggesting tissue-specific regulation of Cullin-3 function. The diverse nature of Cullin-3 phenotypes highlights the importance of targeted proteolysis during Drosophila development.
泛素介导的蛋白质水解作用通过突然清除关键效应蛋白来调节蛋白质的稳态丰度并控制细胞内环境稳定。一个多酶系统通过多泛素链的共价连接将蛋白质作为靶标进行降解。蛋白质泛素化的特异性和时机由泛素连接酶控制，例如Skp1 - Cullin - F盒蛋白复合物。Cullins是SCF复合物的主要成分，并且与包括细胞周期蛋白E、β-连环蛋白和截断翅脉蛋白在内的关键调节分子的降解有关。在这里，我们描述了果蝇Cullin - 3同源物的基因鉴定和分子特征。Cullin - 3功能的扰动在发育过程中具有多效性作用，包括外部感觉器官发育、模式形成以及细胞生长和存活方面的缺陷。Cullin - 3的缺失或过表达分别导致外部感觉器官形成的减少或增加，这表明Cullin - 3功能在调节细胞向神经命运的定向分化中发挥作用。我们还发现Cullin - 3功能通过调节全长截断翅脉蛋白（Ci155）的稳定性来调节Hedgehog信号通路。在眼盘中而非其他成虫盘丧失Cullin - 3功能会促进Ci155的细胞自主积累。相反，Cullin - 3的过表达导致在翅、平衡棒和腿的成虫盘中Ci155的细胞自主稳定，但在眼成虫盘中则不然，这表明Cullin - 3功能存在组织特异性调节。Cullin - 3表型的多样性突出了靶向蛋白水解在果蝇发育过程中的重要性。
