TRANSCRIPTION FACTOR TARGET OF RAS/RAF-1 PATHWAY

许多生长因素影响细胞分裂或分化的决定 通过与特定受体酪氨酸激酶(RTK)结合来区分 细胞膜。RTK的激活已被发现通过一种 一系列常见的中间体，激活MAP(丝裂原激活的 蛋白质)激动酶。不同RTK作用的特异性可能是由于， 至少在一定程度上，与转录因子的多样性有关 这些映射的激活码。很少有转录因子被证明是 激活的RTK途径的直接靶点；对athe的了解更少 这些被激活的转录因子调控的基因。 我们的目标是鉴定和鉴定转录因子靶标 一种基因上描述良好的RTK。躯干(TOR)激活的通路 RTK，它的作用是在早期的两极建立命运 果蝇胚胎，是唯一适合于研究鉴定一种 受RTK调控的转录因子。这一途径已在#年研究过 详细说明基因及其大部分成分的鉴定；分期果蝇 可以收集适合蛋白质纯化的数量的胚胎。 我们已经确定了一个小的(&lt；14个碱基)Tor反应元件(Tor-RE) 无尾(Tll)基因的启动子(受TOR调控的关键基因 路径)。Tor-RE的不同寻常之处在于它扮演着抑制元件的角色； 其功能在Tor RTK激活的细胞中失活， 允许转录Tll。鉴定蛋白质(Tor-Reb) 与Tor-RE结合，并鉴定其在Tor RTK途径中的功能 可能在其他途径上，我们建议做以下工作：1)进一步 通过定点突变确定推定的Tor-RE 转型分析，2.)纯化转录因子(Tor-Reb) 它与Tor-RE绑定，3。)克隆并测序编码Tor-2的基因 Reb，4.)描述TOR-REB和组件之间的相互作用 TOR系统(特别是MAPK)，5.鉴定Tor-Reb RNA和 果蝇发育过程中蛋白质的表达，6)实施遗传 对Tor-Reb基因的研究以确定其在末端的功能 并评估其在不同途径和发育中的作用。 流程。7.)鉴定Tor-reb的哺乳动物同源基因并进行测试 在脊椎动物中，它是否受RTK激活途径的调控。这些 研究有望为分子生物学提供新的见解。 RTK激活通路影响细胞分化和细胞分化的机制 增殖，并可能确定用于诊断筛查的遗传靶点 癌症。

Many growth factors affect the decision of a cell to divide or differentiate by binding to a specific receptor tyrosine kinase (RTK) in the cell membrane. Activation of RTKs has been found to lead, through a series of common intermediates, to activation of MAP (mitogen-activated protein) kinases. The specificity of effect of different RTKs may be due, at least in part, to the diversity of transcription factors modulated by these MAP kinases. Very few transcription factors have been shown to be direct targets of an activated RTK pathway; even less is known about athe genes that these activated transcription factors regulate. Our goal is to identify and characterize the transcription factor target of a genetically well described RTK. The pathway activated by the torso (tor) RTK, which functions to establish fate at the two poles of the early Drosophila embryo, is uniquely suited for studies to identify a novel transcription factor modulated by an RTK. This pathway has been studied in detail genetically and most of its components identified; staged Drosophila embryos can be collected in quantities suitable for protein purification. We have identified a small (<14 bp) tor Response Element (tor-RE) in the promoter of the tailless (tll) gene (the key gene regulated by the tor pathway). The tor-RE is unusual in that it acts as a repressor element; its function is inactivated in cells in which the tor RTK is active, allowing transcription of tll. To identify the protein (the tor-REB) binding to the tor-RE, and characterize its function in the tor RTK pathway and possibly in other pathways, we propose to do the following; 1.) further determine the presumptive tor-RE by site-directed mutagenesis and transformation analysis, 2.) purify the transcription factor (the tor-REB) that binds to the tor-RE, 3.) clone and sequence the gene encoding the tor- REB, 4.) characterize the interaction between the tor-REB and components of the tor system (particularly mAP kinase), 5.) characterize tor-REB RNA and protein expression during development in Drosophila, 6.) carry out genetic studies on the tor-REB gene to confirm that it functions in the terminal pathway, and to assess its role in different pathways and developmental processes. 7.) Identify the mammalian homolog of the tor-REB and test whether it is modulated by RTK activated pathways in vertebrates. These studies are expected to provide novel insights into the molecular mechanisms by which RTK activated pathways affect cell differentiation and proliferation, and may identify genetic targets for diagnostic screening in cancer.