SPECIFICITY OF NOTCH SIGNALING IN FEATHER DEVELOPMENT

Notch信号通路高度保守，在胚胎发育过程中被用来决定细胞的命运。这里提出的研究将解决Notch 1和Notch2在体内如何不同地发出信号来影响细胞命运决定和羽毛发育领域的模式。这个问题将通过检测激活的Notch 1和Notch2的异位表达(通过逆转录病毒介导的基因转移)对Notch信号通路中已知基因的表达和芽发育的影响来进行研究。初步数据表明，Notch1介导羽毛促进信号，Notch2在早期花蕾和芽间命运决定过程中介导抑制信号。Notch信号通路组件的野生型表达模式将在发育中的芽中确定。Notch信号通路中的显性负性和激活形式的效应基因将被用来区分Notch 1和Notch2信号通路。将进行结构域交换实验，以确定Notch 1和Notch2受体的哪一部分有助于信号特异性，从而不同地影响芽发育中细胞命运的决定。所有四种脊椎动物Notch受体的突变导致结构性信号，在肿瘤过程中起着因果作用。因此，从生物学的角度研究Notch1和Notch2受体激活的信号通路，将有助于更好地理解它们在肿瘤发生中的潜在作用。

The Notch signaling pathway is highly conserved and is used in numerous cell fate decisions during embryogenesis. The research proposed here will address how Notch 1 and Notch2 signal differently in vivo to affect cell fate decisions and patterning in the developing feather field. This query will be investigated by examining the effects of ectopic expression of activated Notch 1 and Notch2 (by retroviral mediated gene transfer) on the expression of known genes in the Notch signaling pathway and bud development. Preliminary data indicate that Notch 1 mediates a feather promotion signal and Notch2 mediates an inhibitory signal during early bud and interbud fate decisions. Wild-type expression patterns of Notch signaling pathway components will be determined in the developing bud. Dominant negative and activated forms of effector genes in the Notch signaling pathway will be used to distinguish the Notch 1 and Notch2 signaling pathways. Domain swap experiments will be done to determine which part of the Notch 1 and Notch2 receptors contribute to the signaling specificity that differentially affects cell fate decisions in bud development. Mutations in all four vertebrate Notch receptors leading to constitutive signaling play a causal role in neoplastic processes. Therefore, the study of signaling pathways by constitutively activated Notch 1 and Notch2 receptors in a biological context, as outlined in this proposal, will lead to a better understanding of their underlying role in tumorigenesis.