Protein/nucleic Acid Interactions In Vertebrate Embryoge

在脊椎动物中，外胚层在原肠胚形成期间被细分为四个主要命运：分别在腹侧和背侧表面上的表皮和中枢神经系统（CNS），以及位于这两个域之间的神经嵴和感觉基板。该项目的目标是了解决定外胚层细胞如何在这些途径中进行选择的机制，以及随后的组织模式和分化如何受到调节，主要关注神经嵴。非洲爪蟾的神经嵴诱导需要两种信号，部分减弱的BMP信号和Wnt/β连环蛋白信号。我们发现转录因子TFAP 2 α负责将BMP信号传递到基因组，并激活广泛的神经嵴特异性基因。我们使用了一种可诱导的AP 2 α作为工具，结合微阵列分析来鉴定表皮和神经嵴中的靶基因。我们现在的研究重点是确定其中一小部分基因的功能。特别是，我们对两个基因感兴趣;一个是我们命名为“印加”的基因（AP 2诱导的神经嵴）。印加在青蛙、小鼠和斑马鱼中的序列和表达模式是保守的。在青蛙和斑马鱼中，我们使用了反义寡核苷酸，以表明印加是颅面软骨和骨骼以及其他神经嵴相关组织正常发育所必需的。酵母双杂交分析已经确定了p21激活的激酶PAK 4作为与印加的相互作用伴侣，支持印加在神经嵴细胞迁移和分化过程中调节细胞骨架动力学的模型。另一个基因编码一种新的原钙粘蛋白，PCNS，这是一种短暂表达在神经嵴和发育体节的粘附分子。PCNS的缺失导致神经嵴细胞迁移的失败以及体节和中轴肌发育的异常。由于这些基因在整个脊椎动物的生殖过程中是保守的，我们希望我们的研究结果与生物医学研究和人类健康和发展具有广泛的相关性。

In vertebrates, the ectoderm is subdivided during gastrulation into four primary fates: epidermis and central nervous system (CNS) on the ventral and dorsal surfaces, respectively, and neural crest and sensory placodes located between these two domains. The goal of this project is to understand the mechanisms that determine how ectodermal cells choose among these pathways, and how the ensuing tissue patterning and differentiation are regulated, with a primary focus on the neural crest. Neural crest induction in Xenopus requires two signals, a partially attenuated BMP signal and a Wnt/beta catenin signal. We have found that the transcription factor TFAP2alpha is responsible for conveying the BMP signal to the genome, and activation of a broad spectrum of neural crest-specific genes. We used a hormone-inducible version of AP2alpha as a tool in conjunction with microarray analysis to identifiy target genes in both epidermis and neural crest. We are now focusing our research on determining the function of a small number of these genes. In particular, we are interested in two; one is a gene we named "Inca" (for Induced in Neural Crest by AP2). Inca is conserved in sequence and expression pattern in frogs, mice, and zebrafish. In the frog and zebrafish, we have used antisense oligonucleotides to show that Inca is required for proper development of the craniofacial cartilage and bones and other tissues where neural crest is involved. Yeast two-hybrid analysis has identified a p21-activated kinase, PAK4, as an interaction partner with Inca, supporting a model in which Inca functions to regulate cytoskeletal dynamics during neural crest cell migration and differentiation. Another gene encodes a novel protocadherin, PCNS, which is an adhesion molecule that is transiently expressed in neural crest and developing somites. Loss of PCNS results in failure of neural crest cell migration and also in abnormal somite and axial muscle development. Since these genes are conserved throughout vertebrate phylogeny, we expect our findings to broad relevance to biomedical research and human health and development.