Lissencephaly heterotopia and effects on hippocampal microcircuitry

摘要： 这项提案将研究细胞定位在建立突触连接中的作用。冲向 为此，实验将在一种人类神经发育障碍--无脑畸形的小鼠模型上进行。 大约每100,000名活产儿中就有1名患有无脑畸形，其主要原因是细胞必需基因的突变 扩散和迁移；其中最常见的，也是最早发现的是LIS1。在弱脑症患者中，就像其他 小头畸形，细胞在胚胎发育过程中不能正常迁移，导致异位细胞团。在这 在小鼠模型中，异位细胞带形成，而不是在正常海马区发现的单一主细胞层。 目标1中的实验将确定异位带是否具有共同特征，这可能表明 在非突变的海马体中，离散的兴奋性细胞类型，或者也可以指示异位带 种族隔离似乎是随机的。在第一个目标中将使用几种方法，包括逆行珠子 注射、免疫组织化学和细胞形态重建的体外全细胞记录。在……里面 无论结果如何，Aim 2中的实验都将使用该模型作为一种工具来研究细胞定位在 通过分析异位带内和异位带之间的神经元间连接性来确定突触伙伴。 记录将从已识别的中间神经元进行，而谷氨酸则未在占据各种异位的细胞上进行记录 条带检查突触神经分布的空间分布。这些实验将产生关于 突触拓扑，然后可以与异位条带位置和兴奋性细胞身份进行后对齐。这些 这些发现将增加我们对携带Lis1突变的人群的了解，并从更广泛的角度来看 其他神经发育障碍的细胞异位症。 最近发表的知名期刊表明，兴奋性细胞亚型可能存在于大脑中动脉的放射轴。 海马主细胞层，这是一种以前出于技术目的进行研究不切实际的可能性。一个更伟大的 了解兴奋性和抑制性细胞亚群特定亚群之间连通性的规范形式 似乎准备在神经科学领域迎来新一轮的科学进步。这可能会揭示出 针对特定大脑功能的专用电路，提供新的治疗靶点，同时减少偏离靶点 效果。由于寨卡病毒的传播，小头症重新引起了公众的关注，寨卡病毒可以 通过胚胎接触病毒会导致婴儿小头畸形症。为了提高生活质量和长远 对于这些患者的预后，科学界需要更深入地了解发育障碍和 细胞迁移影响突触连接。

Abstract: This proposal will examine the role of cellular positioning in the establishment of synaptic connectivity. Toward this end, experiments will be carried out in a mouse model of a human neurodevelopmental disorder, lissencephaly. Lissencephaly affects approximately 1 in 100,000 live births and mainly results from mutations in genes essential to cell proliferation and migration; the most common of which and first identified is Lis1. In lissencephaly patients, like other microcephalies, cells fail to properly migrate during embryonic development, resulting in heterotopic cell clusters. In this mouse model, heterotopic cell bands form instead of the single principal cell layer found in the normal hippocampus. Experiments in Aim 1 will determine if heterotopic bands share common features, which might suggest the existence of discrete excitatory cell types in the non-mutant hippocampus, or alternatively may indicate that heterotopic band segregation appears to be random. Several methods will be employed in this first aim, including retrograde bead injections, immunohistochemistry, and in vitro whole-cell recordings with cellular morphological reconstructions. In either outcome, experiments in the Aim 2 will use this model as a tool to investigate the effect of cellular positioning in the determination of synaptic partners by assaying interneuron connectivity within and between heterotopic bands. Recordings will be made from identified interneurons while glutamate is uncaged on cells occupying various heterotopic bands to examine the spatial distribution of synaptic innervation. These experiments will yield detailed information about synaptic topology that can then be post-hoc aligned with heterotopic band locations and excitatory cell identity. These findings will add to our understanding of the human population carrying the Lis1 mutation, and also more broadly to cellular heterotopias in other neurodevelopmental disorders. Recent high-profile journal publications indicate that excitatory cell sub-types might exist in the radial axis of the hippocampal principal cell layer, a possibility that was previously impractical to study for technical purposes. A greater understanding of canonical forms of connectivity between specific subsets of excitatory and inhibitory cell populations seems poised to usher in a new wave of scientific progress in the field of neuroscience. This may reveal the existence of dedicated circuitry for specific brain functions, offering new therapeutic targets and simultaneously reducing off-target effects. Microcephalies have garnered renewed attention from the public owing to the spread of the Zika virus, which can cause microcephaly in babies exposed to the virus embryonically. In order to improve the quality of life and long-term prognosis for these patients the scientific community needs a deeper understanding of how disorders of development and cell migration influence synaptic connectivity.