Translating OCD gene-association studies into mice to examine SLC1A1 function

描述(由申请者提供)：纽约州精神病学研究所和范德比尔特大学的科学家之间为研究强迫症的病理生理学提供了为期两年的合作资助。该提案通过将研究团队正在进行的人类基因研究的结果整合到拟议的小鼠实验中，将基础和临床强迫症研究联系起来。因此，该研究计划充分利用了该团队在1)人类强迫症基因研究、2)转基因小鼠开发、3)生化分析和4)小鼠行为分析方面的专业知识。目前对强迫症潜在的分子和细胞异常的了解有限，部分原因是尚未对人类进行尸检研究。此外，小鼠的研究尚未令人信服地将其与强迫症患者的临床表型和遗传异常联系起来。到目前为止，在人类遗传学研究中，唯一与强迫症有关的基因是SLC1A1，它编码一种运输神经递质谷氨酸的蛋白质。此外，有来自人类研究的证据表明，纹状体内谷氨酸传递的异常调节与强迫症症状有关。这导致了一种假设，即纹状体中SLC1A1谷氨酸转运体的异常水平导致1)谷氨酸系统异常，2)大脑结构改变，3)强迫症症状。拟议中的R21将使用新的敲入鼠标技术来验证这一假设。在第一个目标中，研究人员将使用他们之前开发的一种有效的系统来操纵小鼠的基因表达，该系统被称为FAST系统(灵活的加速停止Teto-Knokkin)。这将使他们能够开发一种名为Teto-SLc1a1的新型敲入小鼠系，这将允许精确调节与强迫症有关的大脑区域中SLC1A1的表达水平。然后，他们将利用这一小鼠品系产生异常高水平的SLC1A1谷氨酸转运体，特别是在纹状体。这将模拟强迫症患者中最常见的基因版本的效果。在第二个目标中，纹状体内SLc1a1水平异常高的小鼠的特征将是：1)测量谷氨酸系统功能~2)检查大脑结构~3)测试与强迫症相关的范例中的行为，测量焦虑和重复行为。这将提供第一个关于强迫症相关功能障碍是否由人类强迫症候选基因异常表达引起的直接测试。完成这项资助将带来一个顺从的系统，用于1)进一步剖析观察到的变化的分子、细胞和电生理学基础，以及2)确定在发育过程中是否存在大脑更容易患强迫症的特定时间。这些研究将有助于更好地理解回路障碍是如何导致强迫症症状的，这对于指导这种严重精神疾病的新治疗方法的开发是必要的。

DESCRIPTION (provided by applicant): Support is requested for a 2-year collaborative grant between scientists at the New York State Psychiatric Institute and Vanderbilt University to investigate the pathophysiology underlying OCD. The proposal bridges basic and clinical OCD research by integrating findings from the research team's ongoing human genetic studies into the proposed mouse experiments. The research plan thus capitalizes on the expertise of the team in 1) human OCD genetic studies, 2) development of transgenic mice, 3) biochemical assays, and 4) mouse behavioral analysis. Current understanding of the molecular and cellular abnormalities underlying OCD is limited, in part because post-mortem studies in humans have not been performed. In addition, mouse studies have not yet been convincingly linked to the clinical phenotype and genetic abnormalities seen in OCD patients. To date, the only gene which has been consistently linked to OCD in human genetic studies is SLC1A1, which codes for a protein that transports the neurotransmitter glutamate. In addition, there is evidence from human studies that abnormal regulation of glutamate transmission in striatum is correlated with OCD symptoms. This has led to the hypothesis that abnormal levels of the SLC1A1 glutamate transporter in striatum lead to 1) abnormalities in the glutamate system, 2) changes in brain structure, and 3) OCD symptoms. The proposed R21 will test this hypothesis using novel knock-in mouse technology. In the first aim, the researchers will use an efficient system they have previously developed for manipulating gene expression in mice called the FAST system (Flexible Accelerated STOP TetO-knockin). This will allow them to develop a novel knock-in mouse line called tetO-Slc1a1, which will permit precise regulation of SLC1A1 expression levels in brain regions implicated in OCD. They will then use this mouse line to generate abnormally high levels of the SLC1A1 glutamate transporter specifically in striatum. This will simulate the effect of the version of the gene found most commonly in OCD patients. In the second aim, the mice with abnormally high levels of Slc1a1 in striatum will be characterized by: 1) measuring glutamate system functioning~ 2) examining brain structure~ and 3) testing behavior in OCD-relevant paradigms that measure anxiety and repetitive behaviors. This will provide the first direct test of whether OCD-related dysfunction is caused by abnormal expression of the leading human OCD candidate gene. Completion of this grant will lead to an amenable system for 1) further dissection of the molecular, cellular, and electrophysiologic underpinnings of observed changes~ and 2) determination of whether there is a particular time in development during which the brain is more vulnerable to developing OCD. These studies will lead to a better understanding of how dysfunctional circuits lead to OCD symptoms, which is necessary to guide development of new treatments for this severe mental illness.