FGD1/CDC42: SIGNAL TRANSDUCTION & DEVELOPMENTAL GENETICS

描述：本研究旨在分析分子遗传学 面生殖发育不良 (FGDY)，一种 X 连锁发育障碍， 对多种骨骼结构的形成产生不利影响，包括 面部、脊柱和四肢远端的元素。 负责的基因 对于这种疾病，FGD1 编码鸟嘌呤核苷酸交换因子 (GEF) 专门激活 Rho（Ras 同源）家族成员 Cdc42 p21 GTP 酶。 通过激活 Cdc42，FGD1 刺激成纤维细胞 形成丝状伪足，参与细胞信号传导的细胞骨架元件， 粘附和迁移。 通过 Cdc42，FGD1 还激活 应激激活蛋白激酶 (SAPK) 信号级联反应 调节细胞生长和分化。 初步研究表明 FGD1 主要在骨骼祖细胞中表达，包括椎骨 软骨前凝结、颈椎骨化和骨化 颅面骨，FGDY 中受影响的骨骼。 不过，数据也显示， 哺乳动物基因组含有多个 FGD1 同源物，这一结果表明 FGD1 可能是部分冗余 Cdc42 激活的组成部分 系统。 总之，累积的数据表明 FGD1 是一个组件 细胞发育调控信号通路的研究 形态学和哺乳动物骨骼发生。 该应用程序的总体目标是开发一个综合模型 进一步阐明 FGD/Cdc42 信号级联在 哺乳动物的形态发生。 为此，交叉杂交和简并 PCR 扩增技术将用于分离额外的 FGD1 同系物；小鼠和斑马鱼 FGD cDNA 克隆将用于确定 胚胎发生过程中基因表达的空间和时间模式。 为了提供精确的细胞定位，FGD1 导向的抗体将 用于通过免疫细胞化学研究胚胎组织。 显微注射和 体外测定将用于研究分子生物学并 从分子角度剖析 FGD 蛋白的功能域。 二杂种 和其他分子技术将用于分离和表征 FGD1/Cdc42 信号转导途径的其他成分。 表达重组 FGD1 蛋白的转基因小鼠将用于研究 FGD1 表达失调的发育后果。 将产生 FGD 缺陷小鼠来研究发育后果 无效 FGD 基因型。 将产生化合物 FGD 缺陷小鼠 检查 FGD 同系物的功能冗余。 这些分析将 提供研究 FGD/Cdc42 信号分子遗传学的方法 哺乳动物形态发生中的转导途径。 这些分析应该 导致对骨骼发生、信号的更彻底的了解 转导，以及负责多样性的一般原则 骨骼形态。

DESCRIPTION: This research aims to analyze the molecular genetics of faciogenital dysplasia (FGDY), an X-linked developmental disorder that adversely affects the formation of multiple skeletal structures including elements of the face, spine, and distal extremities. The gene responsible for this disorder, FGD1, encodes a guanine nucleotide exchange factor (GEF) that specifically activates Cdc42, a member of the Rho (Ras-homology) family of the p21 GTPases. By activating Cdc42, FGD1 stimulates fibroblasts to form filopodia, cytoskeletal elements involved in cellular signaling, adhesion and migration. Through Cdc42, FGD1 also activates the stress-activated protein kinase (SAPK) signaling cascade, a pathway that regulates cell growth and differentiation. Preliminary studies show that FGD1 is primarily expressed in skeletal progenitors including vertebral precartilagenous condensations, ossifying cervical vertebrae, and ossifying craniofacial bones, bones affected in FGDY. However, data also shows that mammalian genomes contain multiple FGD1 homologues, a result that suggests that FGD1 may be a component of a partially redundant Cdc42 activation system. Together, the accumulated data indicates that FGD1 is a component of a developmentally regulated signaling pathway involved in cellular morphology and mammalian skeletogenesis. The overall goals of this application are to develop a comprehensive model to further elucidate the role of the FGD/Cdc42 signaling cascade in mammalian morphogenesis. To this end, cross-hybridization and degenerate PCR amplification techniques will be used to isolate additional FGD1 homologues; mouse and zebrafish FGD cDNA clones will be used to determine the spatial and temporal patterns of gene expression during embryogenesis. To provide precise cellular localization, FGD1-directed antibodies will be used to study embryonic tissue by immunocytochemistry. Microinjection and in vitro assays will be used to study the molecular biology and to molecularly dissect the functional domains of the FGD proteins. Two-hybrid and other molecular techniques will be used to isolate and characterize additional components of the FGD1/Cdc42 signal transduction pathway. Transgenic mice that express recombinant FGD1 proteins will be used to study the developmental consequences of dysregulated FGD1 expression. FGD-deficient mice will be generated to study the developmental consequences of null FGD genotypes. Compound FGD-deficient mice will be generated to examine FGD homologues for functional redundancy. These analyses will provide a means to study the molecular genetics of the FGD/Cdc42 signal transduction pathway in mammalian morphogenesis. These analyses should result in a more thorough understanding of skeletogenesis, signal transduction, and the general principles responsible for the diversity of skeletal form.