Cell adhesion molecules in autism: a whole-brain study of genetic mouse models

描述（由申请人提供）：自闭症包括一系列高度遗传性疾病，目前相关的易感基因正在通过大规模基因组学项目进行鉴定。自闭症基因鉴定的一个重要成果是有可能使用遗传小鼠模型来研究这些基因影响大脑发育和功能的电路、细胞和分子机制。 目前的项目集中在三种携带细胞粘附分子（CAM）突变的小鼠模型上：neuroligin 3 R451 C，neuroligin 4 null和Cntnap 2 null小鼠。这些小鼠被选为与自闭症相关的突触基因大家族的代表，其中包括神经连接素，神经毒素，Cntnap，钙粘蛋白，接触蛋白和Shank蛋白。这些基因中罕见突变的鉴定为自闭症中突触成熟和功能的作用提供了强有力的支持。目前的提议旨在开始剖析三种小鼠模型中的潜在电路和细胞机制。 为了能够比较不同自闭症小鼠模型的大脑功能，我们开发了一种新的方法来对整个小鼠大脑进行高通量成像。这种方法，我们称之为串行双光子（STP）断层扫描，集成了双光子激光扫描显微镜和组织切片。为了通过STP断层扫描研究脑功能，我们使用表达绿色荧光蛋白（GFP）的转基因c-fos-GFP小鼠作为报告基因，用于诱导立即早期基因c-fos。这使我们能够识别异常c-fos诱导的大脑区域，并通过扩展神经激活，在行为任务或全身药物应用过程中诱发。这些异常区域自闭症相关病理学的候选脑区随后成为详细的电生理学和解剖学研究的焦点，旨在确定确切的潜在回路和细胞机制。具体目标是：1。研究CAM突变如何影响调节社会行为的脑回路。2.研究CAM突变如何影响振荡皮层活动和大脑兴奋与抑制的平衡。3.研究候选脑区的解剖连接和细胞生理学。 我们相信，一个成功完成拟议的实验将提供机制的见解，在大脑功能的神经发育的变化，在自闭症的突触基因下游。我们的最终目标是利用这些结果来制定未来治疗策略的开发和测试的假设。

DESCRIPTION (provided by applicant): Autism comprises a spectrum of highly heritable disorders and today the relevant susceptibility genes are being identified by large scale genomics projects. An important outcome of the identification of autism genes is the possibility to use genetic mouse models to study circuit, cellular and molecular mechanisms by which these genes affect brain development and function. The current project is focused on three mouse models carrying mutations in cell adhesion molecules (CAMs): the neuroligin 3 R451C, neuroligin 4 null, and Cntnap2 null mice. These mice were selected as representatives of a larger family of synaptic genes linked to autism, which includes neuroligins, neurexins, Cntnap, cadherin, contactin, and Shank proteins. The identification of rare mutations in these genes provides a strong support for the role of synaptic maturation and function in autism. The current proposal aims to begin to dissect the underlying circuit and cellular mechanisms in the three mouse models. In order to be able to compare brain functions in different autism mouse models, we have developed a novel method for high-throughput imaging of whole mouse brains. This method, which we call serial two- photon (STP) tomography, integrates two-photon laser-scanning microscopy and tissue sectioning. To study brain functions by STP tomography, we use transgenic c-fos-GFP mice that express green fluorescent protein (GFP) as a reporter for the induction of the immediate early gene c-fos. This allows us to identify brain regions with abnormal c-fos induction, and by extension neural activation, evoked during behavioral tasks or by systemic drug applications. Such abnormal regions-candidate brain areas for autism-related pathology-then become the focus of detailed electrophysiological and anatomical studies, which aim to determine the exact underlying circuit and cellular mechanisms. The Specific Aims are: 1. To study how CAM mutations affect brain circuits mediating social behavior. 2. To study how CAM mutations affect oscillatory cortical activity and the balance of brain excitation and inhibition. 3. To study anatomical connectivity and cellular physiology of candidate brain regions. We believe that a successful completion of the proposed experiments will provide mechanistic insights into neurodevelopmental changes in brain functions that lie downstream of the synaptic genes in autism. Our ultimate goal is to use such results to formulate hypotheses for the development and testing of therapeutic strategies in the future.