Molecular Mechanisms of Cerebral Cortical Patterning

描述（由申请人提供）：本研究的主要目标是 确定产生哺乳动物大脑区域图的机制 皮层在活体小鼠中使用子宫内电穿孔的创新方法 我们已经发现证据表明，信号分子FGF 8指定 从大脑前部的一个来源， 端脑修饰内源性前部FGF 8信号使沿着 新皮质的前/后（A/P）轴，并引入新的 FGF 8的后来源使部分区域重复， 异位躯体感觉桶场这些研究的第一个目的是 确定FGF 8是否可以充当调节图案化的主信号，以及 皮层区域图沿着A/P轴的分化。实验将 利用子宫内电穿孔来操纵FGF 8信号传导， 将在出生后进行分析时，新皮质区是可识别的经典 连接和细胞结构标准。第二个目标是测试 假设前部FGF 8源与第二来源的FGF 8相互作用， 信号蛋白，皮质血红素，被认为是调节皮质模式的蛋白质。 沿着内侧/外侧轴线。这种互动将促进协调 沿着大脑皮层的两个主轴沿着形成图案。第三个目标是 以阐明皮质原基的FGF信号机制。 使用FOF和FGF受体结构的电穿孔，我们将确定 除了FGF 8之外，FGF家族成员还可以构成内源性 图案化信号，哪些受体介导信号，以及FGF是否 信号的作用是直接或通过一个中继器使皮层原基形成图案 机制最后，我们将试图确定在细胞内的分子机制， 在区域模式化中的FGF信号传导的下游。特别是，分析 FGF 8和转录因子Emx 2之间的关系，也涉及A/P 皮质图案，我们将采用电穿孔介导的基因转移到 缺少Emx 2功能的鼠标线。 几种涉及骨骼和中枢神经系统异常的人类出生缺陷， 已追踪到FGF受体FGFR 3的突变，FGFR 3编码 高亲和力FGF 8受体。特别是，这些突变导致迄今为止 无法解释的大脑皮层发育缺陷。建议的重点 关于早期皮质模式中FGF 8和FGFR 3信号传导的研究应该澄清 这些缺陷是如何产生的。更一般地说， 大脑皮层的分子机制应该能阐明 遗传性疾病，导致畸形和错误的这一部分， 大脑

DESCRIPTION (provided by applicant): The broad goal of this research is to identify the mechanisms that generate the area map of the mammalian cerebral cortex. Using the innovative method of in utero electroporation in living mouse embryos we have found evidence that the signaling molecule FGF8 specifies positional identity in the neocortex from a source in the anterior telencephalon. Modifying the endogenous anterior FGF8 signal shifts areas along the anterior/posterior (A/P) axis of the neocortex, and introducing a new posterior source of FGF8 elicits a partial area duplication with the formation of ectopic somatosensory barrel fields. The first aim of these studies is to determine if FGF8 can act as a master signal that regulates the patterning and differentiation of the cortical area map along the A/P axis. Experiments will utilize in utero electroporation to manipulate FGF8 signaling, and the area map will be analyzed postnatally when neocortical areas are identifiable by classic connectional and cytoarchitectonic criteria. The second aim is to test the hypothesis that the anterior FGF8 source interacts with a second source of signaling proteins, the cortical hem, proposed to regulate cortical patterning along the medial/lateral axis. Such an interaction would promote coordination of patterning along the two major axes of the cerebral cortex. The third aim is to clarify the FGF signaling mechanism that patterns the cortical primordium. Using electroporation of FOF and FGF receptor constructs, we will determine which FGF family members, in addition to FGF8, may constitute the endogenous patterning signal, which receptors mediate the signal, and whether the FGF signal acts to pattern the cortical primordium directly or via a relay mechanism. Finally, we will attempt to identify molecular mechanisms that lie downstream of FGF signaling in area patterning. In particular, to analyze the relation between FGF8 and the transcription factor Emx2, also implicated in A/P cortical patterning, we will employ electroporation-mediated gene transfer into a mouse line lacking Emx2 function. Several human birth defects that involve skeletal and CNS abnormalities have been traced to mutations in the FGF receptor FGFR3, which encodes a high-affinity FGF8 receptor. In particular, these mutations lead to hitherto unexplained defects of cerebral cortical development. The focus of the proposed studies on FGF8 and FGFR3 signaling in early cortical patterning should clarify how these defects are generated. More generally, an understanding of the molecular mechanisms that pattern the cerebral cortex should shed light on genetic disorders that lead to malformation and mispatterning of this part of the brain.