Cell Growth Signaling in Cancer Development

项目摘要 MTOR途径是一种信号系统，它调节生长和代谢，以响应 有机体的营养状态。越来越多的证据表明，该途径通常在 癌症、神经疾病和糖尿病，也调节衰老过程。MTOR蛋白 激酶是药物雷帕霉素的靶标和两个多蛋白复合体的催化亚单位， MTOR复合体1(MTORC1)和2(MTORC2)，核化途径的不同分支和 响应不同的上行信号。MTORC1对各种刺激有反应，包括不同类型 生长因子、营养物质和压力，并调节许多合成代谢和分解代谢过程， 分别包括蛋白质、核苷酸、脂类合成和自噬。最近，我们发现 MTORC1部分通过溶酶体感知营养，并识别出一种多通道溶酶体 膜蛋白SLC38A9，是感知氨基酸精氨酸的关键。SLC38A9原来是 比我们最初预期的要有趣得多，因为它不仅向mTORC1发出信号，它还具有 在将必需氨基酸从溶酶体中排出以用于胞浆的过程中起主要作用 流程。此外，使用我们开发的一种新方法来描述代谢物含量 溶酶体，我们令人惊讶地发现mTORC1本身是外流的主要调节因子 溶酶体中的大多数非极性必需氨基酸。因此，mTORC1既是下游的，也是 溶酶体功能的上游，表明它是调节和感觉的回路的一部分。 溶酶体能对生长信号作出反应。我们工作的总体目标是达成一个 对溶酶体如何向mTORC1发出信号以及mTORC1如何发出信号的机械理解 调节溶酶体功能。此外，我们发现我们正在研究的机制是 对胰腺癌细胞的增殖尤为重要，因此我们打算测试它们的作用 在小鼠胰腺肿瘤的发展过程中起重要作用。 我们提出的工作的具体目标是：了解溶酶体膜蛋白是如何 SLC38A9控制mTORC1信号转导(目标1)；测试SLC38A9在 胰腺肿瘤(目标2)；并了解mTORC1如何控制溶酶体氨基酸的外流 (目标3)。我们将通过使用以下工具的多学科方法来实现这些目标 生物化学、分子生物学和老鼠工程学。我们的结果将大大增加我们的 了解临床上重要的mTORC1通路并检测SLC38A9是否为潜在药物 胰腺癌的靶点。

Project Summary The mTOR pathway is a signaling system that regulates growth and metabolism in response to the nutritional state of organisms. Increasing evidence shows that the pathway is commonly deregulated in cancer, neurological disorders, and diabetes, and also modulates the aging process. The mTOR protein kinase is the target of the drug rapamycin and the catalytic subunit of two multi-protein complexes, mTOR Complex 1 (mTORC1) and 2 (mTORC2), that nucleate distinct branches of the pathway and respond to different upstream signals. mTORC1 responds to a variety of stimuli, including diverse types of growth factors, nutrients, and stresses, and regulates many anabolic and catabolic processes, including protein, nucleotide, and lipid synthesis and autophagy, respectively. Recently, we discovered that mTORC1 senses nutrients in part through the lysosome and identified a multi-pass lysosomal membrane protein, SLC38A9, that is key for sensing the amino acid arginine. SLC38A9 turns out to be much more interesting than we originally anticipated as not only does it signal to mTORC1 it also has a major role in effluxing an essential amino acid out of the lysosome so it can be used in cytosolic processes. In addition, using a new method we developed to profile the metabolite contents of lysosomes, we made the surprising discovering that mTORC1 itself is a major regulator of the efflux of most non-polar essential amino acids from lysosomes. Thus, mTORC1 is both downstream and upstream of lysosomal function, indicating that it is part of a circuit that modulates and senses lysosome function in response to growth signals. The broad goals of our work are to arrive at a mechanistic understanding of how the lysosome signals to mTORC1 and in turn how mTORC1 regulates lysosome function. In addition, we have found that the mechanisms we are studying are particularly important for the proliferation of pancreatic cancer cells and so we intend to test their roles in the development of pancreatic tumors in mice. The specific aims of our proposed work are to: understand how the lysosomal membrane protein SLC38A9 controls mTORC1 signaling (Aim 1); test the importance of SLC38A9 in the development of pancreatic tumors (Aim 2); and understand how mTORC1 controls the efflux of lysosomal amino acids (Aim 3). We will accomplish these goals with a multi-disciplinary approach that uses the tools of biochemistry, molecular biology, and mouse engineering. Our results will substantially increase our understanding of the clinically important mTORC1 pathway and test if SLC38A9 is a potential drug target in pancreatic cancer.