Molecular Genetics of Segment Determination in Drosophila

9506206 Mann多细胞动物的发展需要所有细胞都有两种类型的信息：它们相对于邻居的位置（位置信息）和它们应该产生什么样的结构（身份信息）。在黑腹果蝇中，同源异型选择基因将这两条信息联系起来：它们的大顺式调节区解释位置信息，它们的蛋白质产物通过调节下游靶基因的转录来控制细胞身份。这些靶基因的特征是重要的，以了解同源异型基因如何决定身份。因此，使用分子筛选分离同源异型靶基因。在这些目标是一个假定的转录因子，预测控制中枢神经系统和细胞骨架的潜在组成部分的成神经细胞的身份。有趣的是，这两个基因的人类同源物都与肿瘤发生有关，这表明在某些情况下，它们可以控制细胞分化和/或增殖。为了研究它们在果蝇发育过程中的野生型功能，将产生这些基因的功能丧失和功能获得突变。将分析这些突变对胚胎形态和基因表达的影响。使用体内错误表达测定，将比较野生型和致癌形式的功能。此外，将使用体内报告基因构建体和体外DNA结合试验研究控制这些基因表达的同源异型响应顺式调控序列。总之，这些实验将提供一个位置信息是如何翻译成身份信息的同源异型基因的理解。 ***

9506206 Mann The development of a multicellular animal requires that all cells have two types of information: where they are relative to their neighbors (positional information) and what structure they should generate (identity information). In Drosophila melanogaster, the homeotic selector genes link these two pieces of information: their large cis regulatory regions interpret positional information and their protein products control cellular identities by regulating the transcription of downstream target genes. These target genes are important to characterize to understand how homeotic genes determine identities. Therefore, homeotic target genes were isolated using a molecular screen. Among these targets is a putative transcription factor that is predicted to control neuroblast identities in the central nervous system and a potential component of the cytoskeleton. Interestingly, the human homologs of both genes are implicated in oncogenesis, suggesting that, in some contexts, they can control cellular differentiation and/or proliferation. To investigate their wild type functions during Drosophila development, loss- and gain-of-function mutations of these genes will be generated. The consequences these mutations have on both embryonic morphology and gene expression will be analyzed. Using in vivo misexpression assays, the functions of the wild type and oncogenic forms will be compared. In addition, the homeotic-responsive cis regulatory sequences that control the expression of these genes will be studied using in vivo reporter gene constructs and in vitro DNA-binding assays. Together, these experiments will provide an understanding of how positional information is translated into identity information by the homeotic genes. ***