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

描述（由申请人提供）：要求支持纽约州立精神病研究所和范德比尔特大学的科学家之间为期2年的合作赠款，以调查强迫症的病理生理学基础。该提案通过将研究小组正在进行的人类遗传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，该研究计划利用了该团队在以下方面的专业知识：1）人类强迫症遗传研究，2）转基因小鼠的开发，3）生化测定，4）小鼠行为分析。目前对强迫症潜在的分子和细胞异常的理解是有限的，部分原因是还没有进行人类的死后研究。此外，小鼠研究尚未令人信服地与强迫症患者的临床表型和遗传异常联系起来。迄今为止，在人类遗传学研究中，唯一与强迫症相关的基因是SLC 1A 1，它编码一种转运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，纹状体中谷氨酸传输的异常调节与强迫症症状相关。这导致了以下假设：纹状体中SLC 1A 1谷氨酸转运蛋白水平异常导致1）谷氨酸系统异常，2）脑结构变化，3）强迫症症状。拟议的R21将使用新的敲入小鼠技术来测试这一假设。在第一个目标中，研究人员将使用他们以前开发的一种有效系统来操纵小鼠的基因表达，称为FAST系统（灵活加速停止TetO敲入）。这将使他们能够开发出一种名为tetO-Slc 1a 1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的SLC 1A 1表达水平。然后，他们将使用这种小鼠品系在纹状体中特异性地产生异常高水平的SLC 1A 1谷氨酸转运蛋白。这将模拟在强迫症患者中最常见的基因版本的效果。在第二个目标中，在纹状体中具有异常高水平的Slc 1a 1的小鼠将通过以下来表征：1）测量谷氨酸系统功能〜 2）检查大脑结构〜和3）在测量焦虑和重复行为的OCD相关范例中测试行为。这将提供第一个直接测试，以确定OCD相关功能障碍是否由人类OCD候选基因的异常表达引起。完成这项资助将导致一个适合的系统，用于1）进一步解剖观察到的变化的分子，细胞和电生理基础，以及2）确定大脑在发育过程中是否有一个特定的时间更容易发生强迫症。 这些研究将有助于更好地了解功能失调的电路如何导致强迫症症状，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。 公共卫生相关性：尽管强迫症（OCD）是一种慢性致残性疾病，终生患病率为2-3%，但我们对OCD病理生理学的了解有限。在人类遗传学研究中，唯一与强迫症相关的基因是SLC 1A 1，它编码一种转运神经递质谷氨酸的蛋白质。该项目将导致创建模拟这种人类遗传发现的小鼠，以便我们可以确定异常的SLC 1A 1表达是否会产生异常的谷氨酸信号，改变大脑结构和/或强迫症样行为。

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. PUBLIC HEALTH RELEVANCE: Despite the fact that Obsessive Compulsive Disorder (OCD) is a chronic, disabling disorder with 2-3% lifetime prevalence, our understanding of OCD pathophysiology is limited. 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. This project will lead to creation of mice that model this human genetic finding, so that we can determine whether abnormal SLC1A1 expression generates abnormal glutamate signaling, altered brain structure, and/ or OCD-like behaviors.