Analysis of JAK Pathway Activation in Drosophila

细胞间的通讯是多细胞生物正常发育和维持的重要因素。作为信号的分子数量是巨大的，然而细胞对信号作出反应的机制却非常有限。有限数量的信号通路作为重新利用的细胞内信号级联已经出现，启动适当的细胞反应。本研究的长期目标是阐明细胞通讯的机制，并了解不同的信号是如何整合和解释以调节发育事件的。在从黏菌到人类的生物体中发现的一个保守的细胞内级联是Janus激酶（JAK）信号通路。在脊椎动物中，JAK信号是细胞对多种细胞因子和生长因子反应的主要机制。之所以选择黑腹果蝇来研究JAK信号，是因为它与人类一样使用JAK信号通路，但可以接受遗传和发育操纵。在果蝇中唯一已知的JAK信号激活因子是Unpaired （Upd）蛋白。先前资助的研究（IBN-9723944）侧重于upd的分子和生化表征。Upd蛋白与之前发现的哺乳动物蛋白没有可识别的相似性，但与果蝇（Drosophila ananassae）密切相关的一种果蝇蛋白相似。在这两种果蝇中都发现了Om（1E）和升级基因。此外，最近发布的果蝇基因组序列已经确定了另外两个与Upd同源的不太保守的预测蛋白。我们将研究这三个新基因的功能，以及它们与upd和彼此之间的关系。对果蝇JAK通路激活的分子和机制的理解将可能为许多多细胞生物的发育信号传导提供见解。本研究的主要目标是：(1)表征果蝇Om（1E）基因的分子、生化和表型特征，(2)确定Om（1E）和upd之间的功能关系，(3)表征另外两个与upd同源的蛋白的分子和表型特征，以及(4)利用遗传筛选识别JAK信号传导和相关途径的其他成分。

0091535HarrisonCommunication between cells is a vital factor in proper development and maintenance of multicellular organisms. The number of molecules that serve as signals is enormous, yet the mechanisms by which cells can respond to signals are much more restricted. A finite number of signaling pathways have emerged as reutilized intracellular signaling cascades that initiate appropriate cellular responses. The long term objectives of this research are to elucidate mechanisms of cellular communication and to understand how different signals are integrated and interpreted to regulate developmental events. One conserved intracellular cascade that has been found in organisms from slime mold to human is the Janus kinase (JAK) signaling pathway. In vertebrates, JAK signaling is the primary mechanism for response of cells to a wide array of cytokines and growth factors. The fruit fly, Drosophila melanogaster, was chosen to study JAK signaling because it uses the JAK pathway in the same manner as humans, yet is amenable to genetic and developmental manipulation. The only known activator of JAK signaling in Drosophila is the Unpaired (Upd) protein. Previously funded research (IBN-9723944) focused on the molecular and biochemical characterization of upd. The Upd protein bears no recognizable similarity to previously identified mammalian proteins, but is similar to a protein from a closely related fruit fly species, Drosophila ananassae. Both Om(1E) and updgenes are found in both of these Drosophila species. Furthermore, the recent release of the Drosophila genome sequence has identified two additional, less conserved predicted proteins that have homology to Upd. The functions of these three new genes will be investigated, as well as the relationships of these genes to upd and to one another. Understanding of the molecules and mechanisms of JAK pathway activation in Drosophila will likely provide insights into developmental signaling in many multicellular organisms. The primary goals of this research are to: (1) characterize, molecularly, biochemically, and phenotypically, the Drosophila melanogaster Om(1E) gene, (2) determine the functional relationships between Om(1E) and upd, (3) characterize, molecularly and phenotypically, two other proteins with homology to Upd, and (4) identify additional components of JAK signaling and related pathways using genetic screens.