Genetic Control of Basal Telencephalic Development

描述（申请人提供）：皮层，纹状体和苍白质是皮质-基底神经节回路的三个关键组成部分-这些回路调节边缘，联想和感觉运动学习。胚胎基底端脑产生皮层下核和皮层中间神经元，这是这些回路功能所必需的。因此，基底端脑发育缺陷会对认知、情绪和运动产生深远的影响。改变感觉运动学习的缺陷可能导致运动表型，例如舞蹈病、震颤和僵硬，在亨廷顿氏病和帕金森病等疾病中可见。改变边缘和联想学习的缺陷可能导致情感和认知缺陷，这可能是图雷特氏症、精神分裂症和成瘾等疾病的基础。胚胎基底端脑主要由内侧神经节隆起（MGE）组成；它产生白球、基底核及其邻近区域的gaba能和胆碱能投射神经元，以及分散在纹状体和皮层的gaba能和胆碱能中间神经元。因此，基底端脑在产生皮层-基底神经节回路的组成部分中起着中心作用。一种阐明调节基底端脑的遗传基础的方法是研究控制该区域产生的神经元发育和功能的转录因子的功能。在本提案中，我描述了研究四种转录因子功能的实验：Nkx2.1 (Aim 2), Lhx6 (Aim 3&4), Lhx7/8 （Aim 3&4）和Ldb1 （Aim 5）。我们假设这四种蛋白的组合和独特功能参与了胚胎基底端脑产生的神经元的身份和特性；下面的图式提供了我们假设的大纲。目的2检测Nkx2.1在SVZ祖细胞、苍白球投射神经元和基底端脑最腹侧区域VZ中的功能。目的3研究Lhx6调控MGE分化的机制。Aim 4检测Lhx6/Lhx7/8是否协同调控MGE的发育，Aim 5检测Ldb1的功能及其表型是否与Lhx6/7(8)突变体相似。此外，我们将使用表达cre的等位基因对胚胎基底端脑产生的细胞进行命运定位研究（Aim 1）；这些等位基因也将成为产生条件突变体的有用遗传工具，例如Aims 2和Aims 5。

DESCRIPTION (provided by applicant): The cortex, striatum and pallidum are three key components of cortico-basal ganglia circuits - these circuits regulate limbic, associative and sensorimotor learning. The embryonic basal telencephalon generates subcortical nuclei and cortical interneurons that are required for the function of these circuits. As such, developmental defects of basal telencephalic development can have a profound influence on cognition, emotion and movement. Defects that alter sensorimotor learning can result in motor phenotypes, as exemplified by chorea, tremor and rigidity seen in disorders such as Huntington's disease and Parkinson's disease. Defects that alter limbic and associative learning can result in affective and cognitive defects that may underlie disorders such as Tourette's, Schizophrenia and addiction. The embryonic basal telencephalon primarily consists of the medial ganglionic eminence (MGE); it produces GABAergic and cholinergic projection neurons of the globus pallidus, nucleus basalis and adjacent regions, and GABAergic and cholinergic interneurons that disperse throughout the striatum and cortex. Thus, the basal telencephalon has a central role in generating components of cortical-basal ganglia circuits. An approach to elucidate the genetic underpinnings that regulate the basal telencephalon is to study the function of transcription factors that control the development and function of the neurons that are produced in this region. In this proposal, I describe experiments that study the functions of four transcription factors: Nkx2.1 (Aim 2), Lhx6 (Aim 3&4), Lhx7/8 (Aims 3&4) and Ldb1 (Aim 5). We hypothesize that combinatorial and unique functions of these four proteins participate in specifying the identity and properties of neurons generated by the embryonic basal telencephalon; the following schema provides the outline of our hypothesis. Aim 2 tests Nkx2.1 function in SVZ progenitors, pallidal projection neurons, and in the VZ of the most ventral regions of the basal telencephalon. Aim 3 studies how Lhx6 regulates MGE differentiation. Aim 4 tests whether Lhx6/Lhx7/8 coordinately regulate MGE development, and Aim 5 tests the function of Ldb1, and whether its phenotypes resemble Lhx6/7(8) mutants. In addition, we will perform fate mapping studies of cells produced in the embryonic basal telencephalon, using Cre-expressing alleles (Aim 1); these alleles will also be useful genetic tools for generating conditional mutants, such as in Aims 2 and 5. PUBLIC HEALTH RELEVANCE: The results from the proposed studies will provide basic information regarding the genetic and developmental mechanisms that control formation of brain regions that control cognition and movement. Disruption of these mechanisms can cause psychiatric and neurological disorders that include mental retardation, autism, schizophrenia, movement disorders and addiction.