果蝇Dscam可产生38016个剪接异构体，这种分子多样性对神经元的自我识别和自我回避至关重要，但这些异构体分子在个体内各个神经元中的表达情况如何至今还不明确，是否可用于神经元身份识别仍无定论。申请人通过修饰Dscam第4外显子族位点构建了12个只表达单一选择性外显子且带HA标签的突变体，本项目将在此基础上系统测定12组Dscam异构体分子在果蝇幼虫体内单个神经元水平上的表达水平，绘制各组异构体分子在一个幼虫外周神经系统的da神经元中的一套完整表达谱，跟踪测定它们在第Ⅳ类da神经元中的各时相表达情况，观察它们在孪生神经元中的表达量是否相同，从而揭示异构体分子在单个神经元水平上的表达规律，并最终阐释“神经元是否依靠蛋白异构体分子的特异性表达来确立自己的身份、神经元的身份是否终身不变、神经元的身份是预先确定好的还是后天决定的”等根本的科学问题，同时也为进一步研究Dscam在相关疾病中的调控机制

Drosophila Dscam undergoes extensive alternative splicing to generate as many as 38,016 isoforms. This diversity is critical for neurite self-recognition. However, it remains unknown how the protein isoforms are expressed in individual neurons of an animal, and whether the isforms is used to be a kind of identity of neurons need to be investigated. We modified the endogenous Dscam locus and generated 12 splicing mutants with a HA tag for all variants of exon 4. This study will focus on systematically imaging and quantitatively assaying the in vivo expression of single isoforms of the alternatively spliced exon 4 cluster at single neuron resolution，to generate the in vivo expression profile of the individual variants in all class IV da neurons and/or all da neurons of dorsal cluster in an animal PNS, to monitor possible changes of the expression over time in an animal by live imaging, to investigate the potential variations of the expression in twin da neurons. The result of the study, which is expected to reveal how the isoforms spliced and expressed in individual neurons, will be of great significance to fundamental scientific issues, such as, whether a neuron establish its identity by express a set of specific isoforms, will the identity of a neuron be changed in different stages of development, and is the identity of a neuron predetermined or acquired during neurogenesis. It will also boost the understanding of related human diseases. NSFC