Molecular Mechanisms of Cerebral Cortical Patterning

描述（由申请人提供）：拟议研究的长期目标是了解启动哺乳动物大脑皮层发育的机制，并控制新皮层区域图的形成。这些发现应该与一系列源于大脑皮层发育缺陷的人类疾病有关。该提议有三个目的，其基于信号分子成纤维细胞生长因子（FGF）8在胚胎小鼠新皮层原基（NP）中充当分级形态原的证据，并启动导致区域图形成的遗传级联。引人注目的是，NP中的异位FGF 8可以诱导重复区域，甚至复杂的图谱。目的1是建立在先前的，系统的搜索候选基因下游的FGF 8和下一个级联，导致皮质区域化。我们使用深度测序（RNA-Seq）来比较NP组织的转录组，在不同的时间表上暴露于不同浓度的FGF 8，模拟FGF 8的自然梯度，以及NP对FGF 8的自然定时暴露。我们已经确定了几个候选基因下游的FGF 8区域表达的NP和其他地方的胚胎图案的链接。我们将使用小鼠遗传学和子宫内微电穿孔将基因转移到活的小鼠胚胎中，以确定候选基因在区域图模式中的作用。目的2将研究FGF 8如何与FGF受体（FGFR）相互作用，以及潜在的内源性FGFR抑制剂和增强剂如何控制FGF 8梯度，从而开发区域图。目的3将探讨嗅球原基（OBP）作为一个有前途的模型系统，以确定有界区域是如何建立在胚胎皮层。OBP是一个明显的有界域，远早于任何新皮层区域。我们有证据表明FGF 8可以诱导继发性OBP，并将进一步研究FGF 8诱导OBP的目的。OBP来源于紧邻前额叶皮层区域的组织。实验将探索这些不同的皮层结构是如何在发育过程中相互分离的。我们实验的部分动机是声称嗅觉缺陷与精神分裂症和自闭症之间存在共同联系。

DESCRIPTION (provided by applicant): Longterm goals of the proposed research are to understand the mechanisms that initiate development of mammalian cerebral cortex, and control formation of the neocortical area map. Findings should be relevant to a range of human disorders that stem from developmental defects in cerebral cortex. This proposal, which has three aims, is based on evidence that the signaling molecule Fibroblast Growth Factor (FGF) 8 acts as a graded morphogen in the embryonic mouse neocortical primordium (NP), and initiates a genetic cascade that leads to formation of the area map. Strikingly, ectopic FGF8 in the NP can induce duplicate areas, and even complex maps. Aim 1 is built on a previous, systematic search for candidate genes downstream of FGF8 and next in the cascade that leads to cortical regionalization. We used deep sequencing (RNA-Seq) to compare transcriptomes of NP tissue, exposed to different concentrations of FGF8 on different time schedules, mimicking the natural gradient of FGF8, and the natural timed exposure of NP to FGF8. We have identified several candidate genes downstream of FGF8 with regional expression in the NP and a link with embryonic patterning elsewhere. We will use mouse genetics and in utero microelectroporation for gene transfer into living mouse embryos to determine the role of the candiate genes in patterning the area map. Aim 2 will investigate how FGF8 interacts with FGF receptors (FGFRs), and how potential endogenous FGFR inhibitors and enhancers control the FGF8 grandient, and, consequently, development of the area map. Aim 3 will investigate the olfactory bulb primordium (OBP) as a promising model system for determining how bounded areas are established in embryonic cortex. The OBP is a distinct bounded domain long before any neocortical areas. We have evidence that FGF8 can induce a secondary OBP and will investigate FGF8 induction of the OBP further in this aim. The OBP is derived from tissue immediately adjacent to the areas of prefrontal cortex. Experiments will explore how these different cortical structures are separated from one another in development. Partial motivation for our experiments here are claims of a common link between olfactory deficits and schizophrenia and autism.