孤独症易感基因NRXN1突变的功能研究

Autism is a brain developmental disorder characterized by impaired social interaction and communication, as well as restricted and repetitive behaviors. The neurexin-1(NRXN1) gene was one of the important candidate genes of autism. Neurexins are highly polymorphic neuronal cell-surface adhesive molecules in mammals, were found involved in synaptogenesis in vitro, but the biological funcation of neurexin in vivo is debating due to multiple genes and thousands of transcripts. In addition, the accurate function of Neurexin involved in synaptogenesis and neurotransmission in autism remains unknown. Our previous study suggest a possible association of NRXN1 with autism risk in Chinese Han population. And we identified 3 missense variants were not reported in the dbSNP database and absent in 500 control subjects.The hypothesis of this study is that the NRXN1 mutations might play an important role in synaptogenesis and synaptic plasticity and involved in the pathogenesis of autism. Based on the hypothesis, we intend to study the synaptogenesis and neurotransmission functions of NRXN1 mutations in vitro (cellular level) and in vivo (Drosophila), respectively. To clarify the effect and mechanism of NRXN1 in synaptogenesis and plasticity,and further elucidate the precise role of NRXN1 in synaptic plasticity and learning memory function.The study will provide functional research basis for the molecular pathogenesis, diagnosis and treatment of autism.

孤独症是一种严重影响儿童健康的精神发育性障碍疾病。NRXN1是孤独症重要的候选基因之一。Neurexin作为突触粘附分子，参与高等动物突触的分化及突触功能的维持，但Neurexin在突触发生和突触传递中精确的作用机制仍未确定。我们的前期工作表明NRXN1与中国人群孤独症发生相关，并在孤独症患者中发现了三个NRXN1的新错义突变。基于此，本课题拟以NRXN1新发突变通过引起突触功能（突触发生和可塑性等）的异常参与孤独症的发病机制作为研究假设，从体外实验（细胞模型）和在体功能分析（果蝇模型）两个方面对这三个NRXN1新发突变的功能进行研究，阐明NRXN1突变对突触发生和突触传递的影响，建立NRXN1和突触可塑性以及学习记忆功能之间的确切关联，以进一步阐明NRXN1在孤独症发病机制中所起的作用。本研究将为阐明孤独症的分子致病机制奠定功能研究基础。

孤独症是一种严重影响儿童健康的精神发育性障碍疾病。NRXN1是孤独症重要的候选基因之一。Neurexin作为突触粘附分子，参与高等动物突触的分化及突触功能的维持，但Neurexin在突触发生和突触传递中精确的作用机制仍未确定。我们的前期工作表明NRXN1与中国人群孤独症发生相关，并在孤独症患者中发现了三个NRXN1的新错义突变。基于此，本课题以NRXN1新发突变通过引起突触功能（突触发生和可塑性等）的异常参与孤独症的发病机制作为研究假设，从体外实验（细胞模型）和在体功能分析（果蝇模型）两个方面对这三个NRXN1新发突变的功能进行研究。结果发现在孤独症患者中发现的三个错义突变的相关突变蛋白的表达、修饰、转运、亚细胞定位在非神经源性的细胞HEK293中与野生型没有差别，但是突变Y315H和L933V可能影响了NRXN1蛋白的降解过程。针对Neurexin1 突变体果蝇进行的突变蛋白表达量水平的分析以及果蝇表型、节律、睡眠、自发运动等行为学分析发现Da-gal4＞dnrx1过表达果蝇dnrx1蛋白水平和野生型比较有显著增高。突变体果蝇与对照果蝇相比运动能力明显下降。过表达突变体Nrx-L893V较过表达野生型相比周期存在差异。dnrx1过表达野生型果蝇夜间睡眠曲线下面积与野生型相比显著降低。进一步的结果分析正在进行中。本研究不仅深入分析了NRXN1的分子功能，而且为进一步阐明NRXN1在孤独症发病机制中所起的作用积累了一定的研究基础。