SIGNALING CELL SPECIFICATION FOREBRAIN

描述（申请人的摘要逐字复制）：刺猬（Hh） 分泌蛋白家族在细胞分化中起着重要作用 在大脑、脊髓、四肢、体节和循环系统中。缺陷 在胚胎发育过程中的Hh信号与人类 先天畸形，包括前脑无裂畸形。Hh的误调节 生命后期的信号传导与基底细胞癌有关， 一种常见的癌症，影响皮肤白皙的成年人。Hh信号通路的研究 因此，对于理解人类先天性 畸形以及某些肿瘤的形成。的主要目标 这个项目是为了了解Hh信号如何有助于细胞 在斑马鱼胚胎的正常发育过程中的分化。我们已经使用 一种遗传学方法来研究Hh信号在形成一个 神经系统的定义区域，腹侧视后区 前脑我们最近发现，两个斑马鱼前脑突变编码 gli家族的hh反应转录因子。细胞分化 斑马鱼前脑突变体的缺陷似乎是由 Hh信号的错误调节。同样，最近也证明了 另一个斑马鱼前脑突变编码音刺猬。的事实 三个斑马鱼前脑突变体编码Hh通路的成员 强调了这种信号级联在发育中的重要性。这 应用程序集中在第四个斑马鱼前脑突变称为umleitung （uml）。与已知的Hh通路突变一样，uml干扰Hh信号传导 和腹侧前脑的细胞分化。我们现在有证据表明 UML可能编码另一种斑马鱼GLI基因。虽然gli基因似乎是 对于Hh信号的调节，对gli基因的功能知之甚少 在脊椎动物中。有证据表明，一些gli基因激活了 Hh靶基因的转录，而其他的作用是抑制Hh靶。我们 建议分析gli介导的hedgehog信号在斑马鱼中的作用 前脑发育：A）鉴定uml编码的基因， uml中的遗传损伤，并分离uml的无效等位基因，B）确定 gli基因如何促进腹侧前脑的细胞分化，C） 确定gli基因如何调节，反过来又受Hh信号的调节 D）鉴定和表征基因，所述基因 斑马鱼胚胎中gli基因的转录调控。斑马鱼 胚胎为研究脊椎动物中Hh的调节提供了一个强有力的模型 因为它允许遗传方法与异位表达研究相结合。 这两种方法的结合非常适合于研究 调节细胞命运决定的分子信号通路， 提供了在其他脊椎动物系统中不容易获得的见解。

DESCRIPTION (Applicant's abstract reproduced verbatim): The hedgehog (Hh) family of secreted proteins plays a fundamental role in cell differentiation within the brain, spinal cord, limbs, somites and circulatory system. Defects in Hh signaling during embryonic development are associated with human congenital malformations, including holoprosencephaly. Mis-regulation of Hh signaling later in life is associated with basal cell carcinoma, the most common form of cancer affecting fair-skinned adults. The study of Hh signaling during development is thus important for understanding human congenital malformations as well as the formation of certain tumors. The major goal of this project is to understand how Hh signaling contributes to cell differentiation during normal development in the zebrafish embryo. We have used a genetic approach to study the role of Hh signaling in the formation of a defined region of the nervous system, the post optic area of the ventral forebrain. We have recently shown that two zebrafish forebrain mutations encode Hh-responsive transcription factors of the gli family. Cell differentiation defects in the zebrafish forebrain mutants appear to be caused by mis-regulation of Hh signaling. Consistently, it was also recently demonstrated that another zebrafish forebrain mutation encodes sonic hedgehog. The fact that three of the zebrafish forebrain mutants encode members of the Hh pathway underscores the importance of this signaling cascade in development. This application focuses on a fourth zebrafish forebrain mutant called umleitung (uml). Like the known Hh pathway mutations, uml interferes with Hh signaling and cell differentiation in the ventral forebrain. We now have evidence that uml may encode another zebrafish gli gene. While gli genes appear to be central to the regulation of Hh signaling, little is known about how gli genes function in vertebrates. There is evidence that some gli genes activate the transcription of Hh target genes, while others act to repress Hh targets. We propose to analyze the role of gli mediated hedgehog signaling in zebrafish forebrain development by A) identifying the gene encoded by uml, determining the genetic lesion in uml, and isolating null alleles of uml, B) determining how gli genes contribute to cell differentiation in the ventral forebrain, C) determining how gli genes regulate, and in turn are regulated by, Hh signaling in vivo, and D) identifying and characterizing genes that are transcriptionally regulated by gli genes in the zebrafish embryo. The zebrafish embryo provides a powerful model for the study of Hh regulation in vertebrates as it allows a genetic approach to be combined with ectopic expression studies. The combination of these two approaches is well suited to the study of molecular signaling pathways that regulate cell fate decisions and promises to provide insights not readily attainable in other vertebrate systems.