Metabolism and Phosphatase Regulation of the TOR Pathway

描述（由申请人提供）：生长过程（质量积累）是细胞、器官和身体大小的关键决定因素，在癌症和糖尿病等疾病中往往不受控制。我们正在研究TOR（哺乳动物中的mTOR；果蝇中的dTOR）通路，这是一个保守的信号系统，在真核生物中作为生长的关键调节因子而出现，并受到代谢、生长因子和应激的调节。TOR通路是fda批准的免疫抑制剂雷帕霉素的靶点，雷帕霉素也用于预防血管成形术后的血管再狭窄，并正在试验中用于治疗癌症和自身免疫性疾病。在过去的几年里，我们一直在研究人类组织培养细胞中mTOR通路的生物化学。尽管这项工作已经取得了丰硕的成果，并且已经发现了几种与mTOR相互作用的蛋白质（例如raptor和GbetaL），但我们已经意识到，关于TOR信号传导的许多重要问题在使用果蝇而不是人类组织培养细胞的模型系统中更容易得到回答。人类和果蝇TOR （dTOR）通路是高度保守的，我们的初步数据表明，这两种通路对营养代谢的反应相似，含有一种未知的TOR调节的磷酸酶，对细胞大小的影响相似。相比之下，酵母TOR通路缺少几个重要的成分，包括S6激酶（S6K）、TSC1和TSC2，它们感知不同的营养物质，并且没有生长因子输入。

DESCRIPTION (provided by applicant): The process of growth (mass accumulation) is a critical determinant of cell, organ, and body size and is often deregulated in diseases such as cancer and diabetes. We are studying the TOR (mTOR in mammals; dTOR in drosophila) pathway, a conserved signaling system that is emerging as the critical regulator of growth in eukaryotes and is regulated by metabolism, growth factors and stress. The TOR pathway is the target of the FDA-approved immuno suppressant rapamycin that is also used to prevent vessel restenosis after angioplasty and is in trials for the treatment of cancer and autoimmune diseases. Over the last few years we have been studying the biochemistry of the mTOR pathway in human tissue culture cells. Although this work has been fruitful and has lead to the discovery of several proteins that interact with mTOR (e.g. raptor and GbetaL), we have come to realize that many of the important questions about TOR signaling are more easily answered in a model system that uses drosophila rather than human tissue culture cells. The human and drosophila TOR (dTOR) pathways are highly conserved and our preliminary data suggests that both pathways respond alike to nutrient metabolism, contain an unidentified TOR-regulated phosphatase, and have similar effects on cell size. In contrast, the yeast TOR pathway is missing several important components, including S6 kinase (S6K), TSC1, and TSC2, senses different nutrients and does not have growth factor inputs. There are several advantages to studying TOR signaling in drosophila rather than human tissue culture cells. The fly pathway has less redundancy than the human version, loss of function mutations are remarkably easy and efficient to make, and we have developed an ultra high-throughput technology (RNAi-cell microarrays) for undertaking genome-scale RNAi screens in drosophila cells. To exploit the potential of the drosophila system to study TOR signaling we propose to: (1) identify and characterize the metabolism-regulated mechanisms that control the TOR pathway; (2) identify and understand the regulation of a TOR controlled phosphatase that inhibits TOR effectors; and (3) use RNAi-cell microarrays to undertake large scale loss of function screens to discover new components of the TOR pathway. In general, we will begin our experiments in the drosophila system and, as our knowledge of a particular problem increases, extend our work to human cells and proteins. Our research will not only lead to a fundamental advance in our understanding of the mechanisms that regulate growth in eukaryotes, but also to the discovery of novel signaling mechanisms that will likely be of value as drug development targets.