Identifying a Role for Vasoactive Intestinal Peptide Expressing Interneurons in a Mouse Model of Dravet Syndrome

项目概要： 我申请这个NRSA奖学金作为一个MD/博士生的长期目标是成为一个成功的 我是一位医生科学家，经营着我自己的转化神经科学研究实验室。这个项目是为了给我 实现这一目标所需的培训和经验。 该项目的目的是调查Dravet癫痫和认知障碍的机制 综合征Dravet综合征是一种严重的儿童神经发育障碍， 自闭症，目前没有治愈或疾病修饰疗法。这种综合征是由基因突变引起的。 基因SCN 1A，其编码电压门控钠通道α亚基Nav1.1。基于在一个 在Dravet综合征小鼠模型中，假设GABA能中间神经元-特别是 以小清蛋白（PV-INs）和生长抑素（SST-INs）的表达为标志-选择性受损， 兴奋性多巴胺能神经元不受影响。中间神经元通常被认为是抑制性的， 中间神经元中Nav1.1的缺失被认为会导致发育中的大脑中抑制作用的降低， 认知障碍和癫痫。然而，中间神经元在基因表达方面是非常多样化的， 形态学、电生理学特性和突触连接性。中间神经元以表达 血管活性肠肽（VIP-IN）构成了第三个重要的中间神经元亚群， 通过主要针对其他中间神经元的去抑制回路，从而调节认知过程， 注意力和学习功能在Dravet综合征中受损。然而，以前的研究没有 研究VIP-IN在该模型中是否受损。我展示的初步数据表明， 在Dravet综合征小鼠模型中表达Nav1.1并具有受损的兴奋性。我假设 导致作为感觉处理和大脑状态调节基础的去抑制微电路的功能障碍。在 目的1，我使用切片电生理学，免疫组织化学和药理学来表明，VIP-IN实际上 表达Nav1.1，并且在Dravet综合征小鼠中功能受损。在目标2中，我将研究 VIP中间神经元功能障碍对Dravet综合征小鼠特定感觉运动回路活动的影响 光遗传学和突触生理学。最后，在目标3中，我将使用双光子钙成像来研究大脑皮层 动态依赖于清醒行为的DS小鼠体内的VIP-IN活性。结果会牵连到VIP Dravet综合征的发病机制中的功能障碍，并提出新的治疗途径。

PROJECT SUMMARY: I am applying for this NRSA fellowship as an MD/PhD student with the long-term goal of becoming a successful physician scientist running my own translational neuroscience research lab. This project is designed to give me the training and experience required towards achievement of this goal. The goal of the project is to investigate the mechanisms of epilepsy and cognitive impairment in Dravet syndrome. Dravet syndrome is a severe neurodevelopmental disorder of childhood defined by epilepsy and autism that is currently without cure or disease-modifying therapy. This syndrome is caused by mutations in the gene SCN1A, which codes for the voltage gated sodium channel alpha subunit Nav1.1. Based on work in a mouse model of Dravet Syndrome, it is hypothesized that GABAergic interneurons – particularly the subsets marked by expression of parvalbumin (PV-INs) and somatostatin (SST-INs) – are selectively impaired, while excitatory glutamatergic neurons are not affected. Interneurons are classically considered to be inhibitory, so loss of Nav1.1 in interneurons is thought to cause decreased inhibition in the developing brain with resulting cognitive impairment and epilepsy. However, interneurons are incredibly diverse in terms of gene expression, morphology, electrophysiological properties, and synaptic connectivity. Interneurons marked by expression of vasoactive intestinal peptide (VIP-INs) constitute a third prominent subset of interneurons that form distinct disinhibitory circuits by primarily targeting other interneurons, and thereby regulate cognitive processing, attention, and learning, functions which are impaired in Dravet Syndrome. However, no previous study has investigated whether VIP-INs are impaired in this model. I show preliminary data indicating that VIP-INs do express Nav1.1 and have impaired excitability in a mouse model of Dravet Syndrome. I hypothesize that this leads to dysfunction of disinhibitory microcircuits that underlie sensory processing and brain state modulation. In Aim1, I use slice electrophysiology, immunohistochemistry, and pharmacology to show that VIP-INs in fact express Nav1.1 and are functionally impaired in Dravet syndrome mice. In Aim 2, I will investigate the effect of VIP interneuron dysfunction on the activity of a specific sensorimotor circuit in Dravet Syndrome mice using optogenetics and synaptic physiology. Finally, in Aim 3, I will use two-photon calcium imaging to study cortical dynamics that depend on VIP-IN activity in awake behaving DS mice in vivo. Results will implicate VIP-IN dysfunction in the pathogenesis of Dravet syndrome and suggest novel avenues for therapy.