Regulation of Ras-Dependent Signal Transduction Pathways

Ras是一种小的、进化上保守的GTPase，其功能是传递调节细胞增殖、分化、存活和转化的信号。致癌Ras蛋白是Ras的组成激活形式，可引起不适当的细胞增殖，并与大约30%的人类恶性肿瘤有关。由于Ras在正常和异常生长过程中都起着至关重要的作用，因此我们实验室的研究重点是阐明Ras依赖性信号转导的参与成分和调节机制。具体来说，我们的研究可以分为四个主要领域：1。丝氨酸/苏氨酸激酶Raf家族的调控。Raf激酶家族在许多信号级联反应中起着重要的中间作用，其功能是从活化的Ras传递信号到下游蛋白激酶MEK和ERK。此外，在67%的恶性黑色素瘤以及许多结直肠癌、卵巢癌和甲状腺乳头状癌中，已经观察到Raf家族成员B-Raf的突变。在这个项目中，我们的目标是研究Raf激酶在生长、发育和肿瘤发生过程中被激活和失活的方式。2. Ras激酶抑制因子（KSR）的功能。通过对果蝇和秀丽隐杆线虫的遗传研究，发现KSR是Ras信号的积极影响因子。我们对哺乳动物KSR蛋白的研究是为了确定KSR转导ras依赖信号的具体机制。3. Ras途径成分的质谱分析。一些Ras通路的组分，如Raf激酶和支架蛋白KSR、CNK和SUR8，存在于哺乳动物细胞的高分子量复合物中。为了鉴定这些复合物的成分并分离Ras通路的其他潜在调节因子，我们的实验室已经开始利用NCI质谱分析设备对这些蛋白质复合物进行全面分析。4. 果蝇的Ras信号通路。由于细胞信号转导的复杂性，我们的实验室一直对使用果蝇作为研究信号事件的模型系统感兴趣。我们目前正在使用该系统来识别ras依赖性信号转导中涉及的新蛋白质。

Ras is a small, evolutionarily conserved GTPase that functions to transmit signals regulating cellular proliferation, differentiation, survival and transformation. Oncogenic Ras proteins, which are constitutively activated forms of Ras, cause inappropriate cell proliferation and are associated with approximately 30% of all human malignancies. Because Ras plays such a critical role in both normal and abnormal growth processes, our laboratory has focused its research on elucidating the components involved in and the mechanisms regulating Ras-dependent signal transduction. Specifically, our studies can be divided into four main areas: 1. Regulation of the Raf family of serine/threonine kinases. The Raf kinase family serves as an essential intermediate in many signaling cascades, functioning to relay signals from activated Ras to the downstream protein kinases MEK and ERK. Moreover, deregulated or constitutively active Raf proteins can themselves cause cell transformation and mutations in the Raf family member B-Raf have been observed in 67% of malignant melanomas as well as in many colorectal, ovarian and papillary thyroid carcinomas. Our goal in this project is to examine the means by which the Raf kinases becomes activated and inactivated during growth, development, and oncogenesis. 2. Function of Kinase Suppressor of Ras (KSR). KSR was discovered to be a positive effector of Ras signaling by genetic studies performed in Drosophila and C. elegans. Our investigation of the mammalian KSR protein has been to determine the specific mechanism(s) by which KSR functions to transduce Ras-dependent signals. 3. Mass spectrometry analysis of Ras pathway components. Several components of the Ras pathway, such as the Raf kinases and the scaffolding proteins KSR, CNK and SUR8, are found in high molecular weight complexes in mammalian cells. To identify the constituents of these complexes and to isolate other potential regulators of the Ras pathway, our laboratory has begun a comprehensive analysis of these protein complexes utilizing the NCI mass spectrometry facility. 4. Ras signaling pathways in Drosophila. Due to the complex nature of cellular signal transduction, our laboratory has had an ongoing interest in using Drosophila as a model system for studying signaling events. We are currently using this system to identify novel proteins involved in Ras-dependent signal transduction.