A systematic test of the relation of ASD heterogeneity to synaptic function

描述（由申请人提供）：虽然自闭症谱系障碍（ASD）具有高度遗传性，但ASD是异质性的，没有单一的遗传原因导致大部分患者的ASD。相反，在ASD中发现了异质性遗传变化，包括许多单基因突变和拷贝数变异（CNVs）。因此，一个关键问题是不同的遗传变化是否通过多个独立的致病途径导致ASD，或者ASD中的各种遗传变化是否汇聚到单一致病途径。编码突触蛋白（如neurexin-1，neuroligins和SHANK 3）的基因中的几个独立突变表明ASD通常可能涉及神经元之间突触通讯的损伤。然而，在ASD中观察到的大多数其他遗传变化对突触没有已知的影响，事实上，对任何大脑功能都没有已知的影响。因此，本提案的主要目标是对ASD中遗传变化的突触效应进行大规模、系统的分析。该方法将是过表达（模拟基因复制）或敲低（模拟基因失活）对应于81个ASD候选基因的mRNA，并使用标准化测定来测试这些操作对突触的影响。将使用PI实验室中完善的光学和电生理测定法，在培养的小鼠神经元中评估细胞活力、神经元发育、突触密度和突触功能。在将慢病毒立体定位注射到小鼠海马体中后，或在子宫内电穿孔后，将通过相同的体内操作研究发现影响培养的神经元中的神经元发育、突触形成或突触功能的基因。然后，使用PI实验室中建立的标准电生理学技术，在这些小鼠的急性切片中检查突触功能和可塑性的变化。该项目的所有结果将公布在一个专门的公共网站上，所产生的所有试剂将随时提供给科学界。该项目的结果将为ASD候选基因的功能提供一个标准化的参考点，并提供一个假设的初步测试，尽管他们的临床和遗传异质性，ASD涉及一个共同的，如果不同的，作用于大脑中的突触通讯途径。 公共卫生相关性：自闭症谱系障碍是已知的临床和遗传异质性，但目前尚不清楚这两种类型的异质性是否相关，以及各种遗传变化如何具体影响大脑功能。该项目将通过研究与自闭症相关的基因引起的神经元间通讯的变化来解决这些问题。

DESCRIPTION (provided by applicant): Although autism spectrum disorders (ASDs) are highly heritable, ASDs are heterogeneous, and no single genetic cause contributes to ASDs in a large proportion of patients. Instead, heterogeneous genetic changes, including many single gene mutations and copy-number variations (CNVs) are found in ASDs. Thus, a key question is whether different genetic changes contribute to ASDs via multiple, independent, pathogenic pathways, or whether the various genetic changes in ASDs converge onto a single pathogenic pathway. Several independent mutations in genes encoding synaptic proteins, such as neurexin-1, neuroligins, and SHANK3, suggested that ASDs may generally involve an impairment of synaptic communication between neurons. However, most of the other genetic changes observed in ASDs have no known effect on synapses in fact, have no known effect on any brain function. Thus, the major goal of the present proposal is to conduct a large scale, systematic analysis of the synaptic effects of genetic changes in ASDs. The approach will be to over express (to mimic gene duplications) or knock down (to mimic gene inactivations) mRNAs corresponding to 81 ASD candidate genes, and to test the effect of these manipulations on synapses using standardized assays. Cell viability, neuronal development, synapse density and synapse function will be assessed in cultured mouse neurons using optical and electro-physiological assays that are well established in the PI's laboratories. Genes that were found to affect neuronal development, synapse formation, or synapse function in cultured neurons will be studied by the same manipulations in vivo after stereotaxic injection of lentiviruses into the mouse hippocampus, or after in utero electroporation. Changes in synapse function and plasticity will then be examined in acute slices from these mice using standard electrophysiological techniques well established in the PI's laboratories. All results from this project will be posted on a dedicated public website, and all reagents generated will be made readily available to the scientific community. The results of this project will provide a standardized reference point for the function of ASD candidate genes, and provide an initial test of the hypothesis that despite their clinical and genetic heterogenity, ASDs involve a common, if diverse, pathway acting on synaptic communication in the brain. PUBLIC HEALTH RELEVANCE: Autism spectrum disorders are known to be clinically and genetically heterogeneous, but it is unclear whether these two types of heterogeneity are related, and how specifically the various genetic changes affect brain function. This project will address these issues by studying the changes in neuron-to-neuron communication caused by the genes associated with autism.