ZC3H11A的UFM1类泛素化修饰调控细胞周期关键mRNAs转运在小头畸形中的机制研究

我们首先报道了UFM1类泛素化通路E1酶UBA5的突变，后续报道明确该通路类泛素、E1和E2突变均会引起患者不同程度的运动障碍、智障和小头畸形。目前已知UFM1化底物和相关生物学功能，都不能解析UFM1缺失如何导致小头畸形。我们前期明确了UFM1通路参与细胞周期调控，影响mRNA转运；筛选到负责mRNA转运的UAP56能够拯救UFM1表型；鉴定了与UAP56相互作用的ZC3H11A会发生UFM1化修饰。本项目将深入研究ZC3H11A的UFM1化修饰水平降低如何影响UAP56的mRNA转运功能，引起细胞周期紊乱，最终导致小头畸形。我们拟确定ZC3H11A发生UFM1化的位点，分析ZC3H11A的UFM1化对UAP56的mRNA转运功能影响，在细胞与类脑模型中鉴定转运功能异常的细胞周期关键mRNAs。本项目将鉴定一个新底物，揭示mRNA转运的新功能，阐明UFM1相关小头畸形的分子致病机制并构建其类脑模型。

Previously, we reported that the mutation of UBA5, the UFMylation activating enzyme (E1 enzyme), causes microcephaly. A number of follow-up reports suggested that the mutations in UFM1, UBA5 or UFC1 (E2 enzyme) could also cause dyskinesia, mental retardation and microcephaly in patients. So far, there are no experiment-validated substrates or known biological functions that could be attributed to the microcephaly caused by the loss of the UFM1 pathway. Our preliminary data showed: UFM1 pathway serves as an essential regulator in the cell cycle using drosophila model; the knockdown of UFM1 results in mRNA export defects; UAP56 knockdown can effectively rescue the UFM1 deletion phenotype by Screening (UAP56 is responsible for the export of some mRNAs, including those involved in the cell cycle); ZC3H11A protein may interact with UAP56 and acts as a new substrate for UFM1. Taken together, our proposed project will continue to investigate how the defective UFMylation of ZC3H11A affects the role of UAP56 in mRNA export, which could, in turn, deregulate the cell cycle and lead to the microcephaly. We will further determine the Lysine site for UFMylation in ZC3H11A, analyze the importance of ZC3H11A UFMylation in the function of UAP56-mediate mRNA export, and identify the mRNAs that are abnormally exported, leading to the deregulation of the cell cycle in cellular and Organoid models. The innovation of this project is to identify a novel UFMylation substrate, reveal the uncovered function of the UFM1 modification, elucidate the pathogenic mechanism of UFM1-pathway-mediated microcephaly at the molecular level, and establish the disease model in the Organoid system to provide the fundamentals for the deep understanding of the pathogenesis.