Characterization and Cloning of Sister of Open Brain

描述（由申请人提供）：控制哺乳动物中枢神经系统早期发育的分子机制仍然知之甚少。小鼠遗传学是研究这一过程的有力工具。在这里，我将研究一个新的隐性致死突变小鼠，姐妹开放脑（sopb），表现出严重的神经管图案缺陷。SOPB是从使用N-乙基-亚硝基脲（ENU）的基于表型的遗传筛选获得的。纯合子突变胚胎不能闭合头神经管和脊髓神经管，并表现出其他缺陷，包括多余的手指和发育不良的眼睛。sopb突变体的神经管腹侧与Shh靶基因的异位表达，和sopb出现Shh的下游功能。该项目的假设是SOPB作为Shh信号通路的拮抗剂。这项研究将侧重于四个目标：1）基于细胞类型的各种标志物和参与细胞-细胞信号传导的基因的表达，研究SOPB突变体中关于神经管模式化的主要缺陷，2）使用嵌合体分析测试野生型SOPB基因产物是否细胞自主或非细胞自主地作用于神经细胞类型特化，3）利用上位性分析将sopb基因定位于Shh信号转导通路中，以及4）定位克隆sopb基因以了解其分子功能。Sonic hedgehog（Shh）通路在胚胎发育中起着重要的作用。该途径的异常活动已被证明会导致出生缺陷和各种癌症。因此，识别和表征该通路的新组分，如SOPB，将具有重要的临床意义。

DESCRIPTION (provided by applicant): The molecular mechanisms controlling the early development of the central nervous system in mammals remain poorly understood. Mouse genetics serves as a powerful tool to investigate the process. Here I will study a new recessive lethal mouse mutant, sister of open brain (sopb), exhibiting severe neural tube patterning defects. sopb was obtained from a phenotype-based genetic screen using N-ethyl-nitrosourea (ENU). Homozygous mutant embryos fail to close the cephalic and spinal neural tube, and exhibit other defects including supernumerary digits and poorly developed eyes. The neural tube of sopb mutants is ventralized with the ectopic expression of Shh target genes, and sopb appears to function downstream of Shh. The hypothesis of this project is that sopb acts as an antagonist of the Shh signaling pathway. This study will focus on four aims: 1) to investigate the primary defects in sopb mutants with respect to neural tube patterning based on the expression of various markers of cell type and of genes involved in cell-cell signaling, 2) to test whether the wild-type sopb gene product acts cell autonomously or non-cell autonomously for neural cell type specification using chimera analysis, 3) to place the sopb gene in the Shh signal transduction pathway using epistasis analysis, and 4) to positionally clone the sopb gene to understand its molecular function. The Sonic hedgehog (Shh) pathway plays important roles in embryonic patterning. The abnormal activity of the pathway has been shown to cause birth defects and various cancers. Therefore, identification and characterization of novel components of the pathway, such as sopb, will have important clinical implications.