NEUROLIGIN AND AUTISM

本子项目是利用由NIH/NCRR资助的中心赠款提供的资源的众多研究子项目之一。子项目和研究者（PI）可能已经从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。列出的机构是中心的，不一定是研究者的机构。自闭症是一种普遍的障碍，与形成社会互动和交流的缺陷、刻板行为的发展和不寻常的兴趣有关。Jamain等人（2003）最近的一项研究报告称，在患有自闭症谱系障碍（ASD）的兄弟姐妹中发现了编码神经胶质素-3 （NL3）和神经胶质素-4 （NL4）的两个x连锁同源基因的突变。神经素，a/b水解酶折叠家族的蛋白质，是突触后跨膜蛋白，与突触前伙伴，b-神经素结合。Neurexin和neuroigin似乎在突触连接中形成异源细胞接触，使它们成为早期大脑发育过程中控制突触识别模式的合适候选者。本研究的目的是确定与ASD相关的人类NL3-R451C突变的生化作用。Arg451在所有物种（从果蝇到人类）中都是高度保守的，它位于一个预测的EF-hand区域附近，该区域被怀疑扰乱了神经素素-神经素关联的Ca2+依赖性。然而，使用截断的可溶形式的FLAG-NL3，我们发现这两个突变蛋白在我们的哺乳动物细胞系统中不作为可溶性实体表达。我们假设突变体Cys471的引入可能会通过与7个天然存在的Cys中的一个产生新的二硫键来破坏蛋白质折叠。我们计划在稳定转染的HEK293细胞中使用免疫荧光观察野生型和突变型全长蛋白的细胞内运输，以确定这两种天然靶向细胞膜的蛋白是否遵循相同的运输途径。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Autism is a pervasive disorder associated with deficits in forming social reciprocal interaction and communications, development of stereotyped behavior and unusual interests. A recent study by Jamain et al. (2003) reports that mutations of two X-linked homologous genes encoding neuroligin-3 (NL3) and neuroligin-4 (NL4) were found in siblings with autism spectrum disorders (ASD). Neuroligins, proteins of the a/b-hydrolase fold family, are postsynaptic transmembrane proteins that associate with presynaptic partners, the b-neurexins. Neurexin and neuroligin appear to form heterologous cell contacts at synaptic connections, making them suitable candidates for controlling synaptic recognition patterns during early brain development.The aim of this study is to determine the biochemical role of the human NL3-R451C mutation associated with the ASD. Arg451 is highly conserved among all species (from fruit fly to human) and it is located near a predicted EF-hand region, where is suspected to perturb the Ca2+ dependence of the neuroligin-neurexin association. However, using a truncated soluble form of FLAG-NL3 we found that both mutant proteins were not expressed as soluble entities by our mammalian cell system. We hypothesize that the introduction of mutant Cys471 might disrupt the protein folding by creating a new disulfide bond with one of the 7 naturally occurring Cys. We plan to visualize the intracellular trafficking of both wild type and mutant full length proteins using immunofluorescence in stably transfected HEK293 cells in order to determine if both proteins, naturally targeted to the cell membrane, follow the same trafficking pathway.