Wang Ying-Hsuan, Ding Zhao-Ying, Cheng Ying-Ju, Chien Cheng-Ting, Huang Min-Lang
Department of Biomedical Sciences, National Chung Cheng University, Chiayi, Taiwan.
Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan.
Front Cell Neurosci. 2020 Sep 25;14:577315. doi: 10.3389/fncel.2020.577315. eCollection 2020.
Dendritic morphology is inextricably linked to neuronal function. Systematic large-scale screens combined with genetic mapping have uncovered several mechanisms underlying dendrite morphogenesis. However, a comprehensive overview of participating molecular mechanisms is still lacking. Here, we conducted an efficient clonal screen using a collection of mapped P-element insertions that were previously shown to cause lethality and eye defects in . Of 280 mutants, 52 exhibited dendritic defects. Further database analyses, complementation tests, and RNA interference validations verified 40 P-element insertion genes as being responsible for the dendritic defects. Twenty-eight mutants presented severe arbor reduction, and the remainder displayed other abnormalities. The intrinsic regulators encoded by the identified genes participate in multiple conserved mechanisms and pathways, including the protein folding machinery and the chaperonin-containing TCP-1 (CCT) complex that facilitates tubulin folding. Mutant neurons in which expression of CCT4 or CCT5 was depleted exhibited severely retarded dendrite growth. We show that CCT localizes in dendrites and is required for dendritic microtubule organization and tubulin stability, suggesting that CCT-mediated tubulin folding occurs locally within dendrites. Our study also reveals novel mechanisms underlying dendrite morphogenesis. For example, we show that Nogo signaling is required for dendrite development and that Mummy and Wech also regulate dendrite morphogenesis, potentially via Dpp- and integrin-independent pathways. Our methodology represents an efficient strategy for identifying intrinsic dendrite regulators, and provides insights into the plethora of molecular mechanisms underlying dendrite morphogenesis.
树突形态与神经元功能紧密相连。系统的大规模筛选与基因定位相结合，已揭示出树突形态发生的几种潜在机制。然而，对于参与其中的分子机制仍缺乏全面的概述。在此，我们利用一组已定位的P元素插入片段进行了高效的克隆筛选，这些插入片段先前已被证明会导致果蝇致死和眼部缺陷。在280个突变体中，52个表现出树突缺陷。进一步的数据库分析、互补测试和RNA干扰验证确定了40个P元素插入基因与树突缺陷有关。28个突变体呈现出严重的树突分支减少，其余的则表现出其他异常。所鉴定基因编码的内在调节因子参与多种保守机制和途径，包括蛋白质折叠机制以及促进微管蛋白折叠的含伴侣蛋白TCP-1（CCT）复合体。CCT4或CCT5表达缺失的突变神经元表现出树突生长严重迟缓。我们发现CCT定位于树突中，并且是树突微管组织和微管蛋白稳定性所必需的，这表明CCT介导的微管蛋白折叠在树突内局部发生。我们的研究还揭示了树突形态发生的新机制。例如，我们发现Nogo信号通路是树突发育所必需的，并且Mummy和Wech也调节树突形态发生，可能是通过不依赖Dpp和整合素的途径。我们的方法代表了一种识别树突内在调节因子的有效策略，并为树突形态发生背后众多的分子机制提供了见解。
