Genetic Screens for Drosophila p70 S6 Kinase Modifiers

哺乳动物p70 S6激酶，又称S6 K1，是一种丝裂原刺激的丝氨酸/苏氨酸激酶，位于一条信号通路上，控制翻译和细胞生长。目前S6 K1功能的模型是，在激活时，S6 K1磷酸化40 S核糖体亚基蛋白S6，这导致核糖体选择性地增加编码核糖体蛋白和翻译起始因子的一组mRNA的翻译。预期这一系列事件将增加核糖体生物合成和细胞的翻译能力，从而允许增加一般蛋白质合成和细胞生长。S6 K1的激活是复杂的，并且与激酶中8个氨基酸的磷酸化有关。导致S6 K1活化的信号通路仅部分确定，并且仅已知使S6 K1中与激酶活化相关的8个磷酸化氨基酸之一磷酸化的激酶之一的身份。果蝇S6激酶同源物dS6 K在结构和功能上与哺乳动物S6 K1保守。在培养的细胞中，激活或抑制S6 K1的试剂可以激活或抑制dS6 K，这表明调节dS6 K和S6 K1激活的机制在果蝇和哺乳动物之间是保守的。与S6 K1在翻译和生长中的作用类似，dS6 K在果蝇中的作用似乎是调节细胞大小、细胞生长和细胞增殖。该提案的总体目标是利用果蝇遗传学的力量来鉴定dS6 K通路的新组分。实现这一目标需要：1。检测编码dS6 K信号通路疑似组分的基因的突变等位基因是否与突变dS6 K等位基因发生遗传相互作用2。筛选果蝇缺乏症原种的集合以鉴定dS6 K突变表型的剂量敏感性修饰剂3。进行诱变筛选，旨在确定新诱导的突变基因编码的dS6 K信号通路的组件。确定dS6 K信号通路的组件将是重要的，以增加我们的细胞内信号的知识，也应该影响我们的理解的基本机制，调节翻译和细胞生长。

Stewart 0077618AbstractThe mammalian p70S6 kinase, termed S6K1, is a mitogen-stimulated serine/threonine kinase that lies on a signaling pathway leading to the control of translation and cell growth. The current model for S6K1 function is that upon activation, S6K1 phosphorylated the 40S ribosomal subunit protein S6 and this causes the ribosome to selectively increase the translation of a group of mRNAs that encode ribosomal proteins and translation initiation factors. This series of events would be expected to increase ribosome biogenesis and the translational capacity of the cell and thus allow increased general protein synthesis and cell growth. The activation of S6K1 is complex and is associated with the phosphorylation of eight amino acids in the kinase. The signaling pathways that lead to S6K1 activation are only partially defined and only the identity of one of the kinases that phosphorylates one of the eight phosphorylated amino acids inS6K1 that are associated with the activation of the kinase is known. The Drosophila melanogaster S6 kinase homolog, dS6K, is structurally and functionally conserved with the mammalian S6K1. In cultured cells, dS6K can be activated or inhibited by agents that activate or inhibit S6K1, suggesting that the mechanisms that regulate dS6K and S6K1 activation will be conserved between Drosophila and mammals. Similar to the proposed role for S6K1 in translation and growth, the role for dS6K within the fly appears to be in regulating cell size, cell growth and cell proliferation. The overall goal of this proposal is to use the power of Drosophila genetics to identify novel components of the dS6K pathway. Reaching this goal will entail:1. Testing if mutant alleles of genes that encode suspected components of the dS6K signaling pathway interact genetically with mutant dS6K alleles2. Screening a collection of Drosophila deficiency stocks to identify dose-sensitive modifiers of dS6K mutant phenotypes3. Performing mutagenesis screens designed to identify newly induced mutations in genes that encode components of the dS6K signaling pathways.Identifying components of the dS6K signaling pathways will be important for increasing our knowledge of intracellular signaling and also should impact our understanding of the basic mechanisms that regulate translation and cell growth.