X-连锁智力障碍新基因REPS2的致病机制初探

我们从两个智力障碍家系中筛选出X连锁致病新基因REPS2。预实验发现，斑马鱼reps2在中枢神经系统高表达，敲低该基因后，神经元形态异常，回补实验证实患者携带突变有害。组织定位实验发现，REPS2/Reps2蛋白表达在人和鼠脑多区域的神经元中。小鼠原代神经元实验发现，Reps2蛋白表达于神经突，敲低该基因后，神经突形态出现明显异常。人源SH-SY5Y细胞系敲低REPS2后，初级内体减少，提示内吞过程受阻。小鼠Reps2突变敲入模型脑切片显示，神经元树突棘显著减少。已知REPS2蛋白参与网格蛋白依赖的内吞过程，我们由此推测其通过该过程调控神经突生长和突触形成。本项目拟通过已构建的小鼠Reps2突变敲入模型，从个体，组织，细胞，分子各个层面揭示其作用机制。本研究首次确证X连锁智力障碍新基因REPS2，并深入探讨细胞内吞过程受阻导致神经突缺陷的致病机制。

We identified a novel X-linked intellectual disability (XLID) gene REPS2 in two families. Preliminary experiments of zebrafish model revealed the enriched expression of reps2 in central nervous system, and abnormal morphology of neurons when reps2 was knocked down. The rescue experiments on zebrafish model confimred the pathogenicity of the mutations found in the patients. Immuno-staining tests observed REPS2/Reps2 preferentially in neurons of multiple brain regions. By using primary murine neurons, we found dramatically abnormal neurites after knocking down Reps2. In REPS2-knocked-out SH-SY5Y cells, the number of early endosomes was significantly reduced, indicating the suppressed endocytosis. Moreover, the Reps2-mutant-knocked-in mice model demonstrated significantly decreased neurite spines. Because REPS2 is known to be involved in the clathrin-dependent vesicle endocytosis, we thus propose its role in regulating neurite growth and synapse formation. In the coming work, we plan to utilize the Reps2-mutant-knocked-in mice model to uncover the underlying mechanism at the levels of organism, tissue, cell, and molecule. This study is the first report of REPS2 as a XLID gene, and carries out an in-depth investigation on defective neurites due to blocked endocytosis.