Activation of rapamycin-sensitive TORC1 by endomembrane amino acid transporters

内膜氨基酸转运蛋白激活雷帕霉素敏感的TORC1

基本信息

批准号：
8021215
负责人：
MARIA E CARDENAS-CORONA
金额：
$ 32.58万
依托单位：
DUKE UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2011
资助国家：
美国
起止时间：
2011-01-01 至 2015-12-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8021215
关键词：
Amino Acid Transporter Amino Acids Area Binding Biological Models Bypass Cancer Biology Cardiology Cell Proliferation Cells Chemotherapy-Oncologic Procedure Chimeric Proteins Clinical Cognitive aging Complex Cues Defect Disease Docking Drosophila genus Ego Endosomes Event Family Fostering Gene Expression Genes Genetic Screening Genetic Transcription Glutamine Goals Growth Growth Factor Guanine Nucleotide Exchange Factors Guanosine Triphosphate Guanosine Triphosphate Phosphohydrolases Homeostasis Human Immunosuppression Insecta Intervention Lead Leucine Link Lysosomes Malignant Neoplasms Mammalian Cell Mammals Mediating Membrane Modeling Molecular Molecular Mechanisms of Action Mutate Mutation Nitrogen Nuclear Import Nuclear Translocation Nutrient Orthologous Gene Pathway interactions Phosphotransferases Play Protein Kinase Proteins Protons Regulation Research Role Saccharomyces cerevisiae Signal Pathway Signal Transduction Sirolimus Sorting - Cell Movement System Testing Therapeutic Agents Trans-Activators Vacuolar Protein Sorting Vacuole Vesicle Work Yeast Model System Yeasts age related analog antiproliferative drugs base cancer therapy cell growth fitness forging human disease improved mTOR protein member novel programs protein complex protein transport response sensor trafficking

项目摘要

DESCRIPTION (provided by applicant): The target of rapamycin complex 1 (TORC1) plays a prominent role in a ubiquitously conserved signal transduction cascade that responds to nutrients and growth factor cues to control cell growth and proliferation. Dysregulation of the TORC1 cascade results in multiple types of human malignancies. The central TORC1 members are the Tor protein kinases, which were discovered in the yeast Saccharomyces cerevisiae, a model system that has been crucial in elucidating the TORC1 signaling cascade. Based on its potent antiproliferative activity, rapamycin is in use in several clinical areas including immunosuppression, cancer chemotherapy, and interventional cardiology. The TORC1 pathway remains partially characterized despite much study. We uncovered an unexpected role for the endomembrane vesicular trafficking system in regulating TORC1 signaling in yeast; mutations in protein complexes with roles in vesicular trafficking and protein sorting in combination with mutation of the nonessential Tor1 kinase, render cells inviable or severely growth impaired. We demonstrated that the HOPS complex is required to provide amino acid homeostasis for efficient TORC1 signaling and for normal expression of TORC1-governed genes. These studies also revealed a novel facet in the rapamycin mechanism of action: rapamycin bypasses vesicular trafficking events to activate TORC1- controlled transactivators. Moreover, we showed that mutations in the Ego complex (EGOC) compromise TORC1 signaling and both EGOC and TORC1 activity are required for optimal cell growth. The EGOC possesses evolutionary conserved amino acid-sensitive GTPase subunits and orthologs of these (Gtr1,2 and RagA-D proteins) mediate TORC1 activation in yeast, insect, and mammalian cells. However, the identity of the amino acid sensors and the underlying mechanisms by which amino acids activate EGOC GTPase are unknown. Intriguingly, TORC1 and the EGOC colocalize to endomembranes including those of endosomes and vacuoles, along with vacuolar amino acid transporters. The aims of this proposal are: 1) to elucidate the roles and underlying mechanism by which the endomembrane system enables TORC1 signaling and 2) to determine whether the vacuolar amino acid transporters, which are conserved in mammals, are integrated into the molecular cascade that conveys amino acid signals to evoke TORC1 activation. Our working model is that the endomembrane network provides a platform to facilitate molecular interactions that activate and enable TORC1 signaling. Similar to yeast TORC1, mammalian TORC1 is also localized to endomembranes, in particular lysosomes, which are the counterparts of yeast vacuoles. Thus, we submit that our research will continue to uncover fundamental, conserved TORC1 signaling aspects that could be directly extrapolated to mammalian models and guide pharmacological intervention in select TORC1 pathway defects in human cancer and other diseases. PUBLIC HEALTH RELEVANCE: The rapamycin sensitive-TORC1 is the central component of an evolutionary-conserved signaling cascade that in response to nutrients and growth factors regulates cell growth and proliferation. Defects in mTORC1 signaling lead to cancer and other human diseases. Rapamycin and its analogs are being developed as therapeutic agents for the treatment of a wide range of malignances and could also find indication in cognitive- and aging-related diseases. The model yeast S. cerevisiae has been crucial in the discovery of the TORC1 pathway and elucidation of rapamycin mechanism of action. Characterization of this pathway in yeast is continuing to reveal basic aspects of TORC1 signaling that could foster analogous studies in mammals and lead to improved anticancer therapies.

描述（由申请人提供）：雷帕霉素复合物 1 (TORC1) 的靶标在普遍保守的信号转导级联中发挥着重要作用，该级联响应营养物和生长因子信号来控制细胞生长和增殖。 TORC1 级联的失调会导致多种类型的人类恶性肿瘤。 TORC1 的核心成员是 Tor 蛋白激酶，它是在酿酒酵母中发现的，这是一个模型系统，对于阐明 TORC1 信号级联至关重要。基于其有效的抗增殖活性，雷帕霉素被用于多个临床领域，包括免疫抑制、癌症化疗和介入心脏病学。尽管进行了大量研究，TORC1 通路仍具有部分特征。我们发现内膜囊泡运输系统在调节酵母中 TORC1 信号传导方面发挥着意想不到的作用；参与囊泡运输和蛋白质分选的蛋白质复合物突变与非必需 Tor1 激酶突变相结合，导致细胞无法存活或严重生长受损。我们证明了 HOPS 复合物需要为有效的 TORC1 信号传导和 TORC1 控制基因的正常表达提供氨基酸稳态。这些研究还揭示了雷帕霉素作用机制的一个新方面：雷帕霉素绕过囊泡运输事件来激活 TORC1 控制的反式激活因子。此外，我们发现 Ego 复合体 (EGOC) 中的突变会损害 TORC1 信号传导，并且 EGOC 和 TORC1 活性都是最佳细胞生长所必需的。 EGOC 拥有进化保守的氨基酸敏感 GTP 酶亚基和这些亚基（Gtr1,2 和 RagA-D 蛋白）的直系同源物，介导酵母、昆虫和哺乳动物细胞中的 TORC1 激活。然而，氨基酸传感器的身份以及氨基酸激活 EGOC GTP 酶的潜在机制尚不清楚。有趣的是，TORC1 和 EGOC 与内膜（包括内体和液泡）以及液泡氨基酸转运蛋白共定位。该提案的目的是：1) 阐明内膜系统实现 TORC1 信号传导的作用和潜在机制；2) 确定在哺乳动物中保守的液泡氨基酸转运蛋白是否整合到传递转运蛋白的分子级联中。氨基酸信号引起 TORC1 激活。我们的工作模型是内膜网络提供了一个平台来促进分子相互作用，从而激活并启用 TORC1 信号传导。与酵母 TORC1 类似，哺乳动物 TORC1 也定位于内膜，特别是溶酶体，它是酵母液泡的对应物。因此，我们认为我们的研究将继续揭示基本的、保守的 TORC1 信号传导方面，这些方面可以直接外推到哺乳动物模型，并指导对人类癌症和其他疾病中特定 TORC1 通路缺陷的药物干预。公共健康相关性：雷帕霉素敏感的 TORC1 是进化保守的信号级联的核心组成部分，该级联响应营养物质和生长因子来调节细胞生长和增殖。 mTORC1 信号传导缺陷会导致癌症和其他人类疾病。雷帕霉素及其类似物正在被开发为治疗多种恶性肿瘤的治疗剂，并且还可以在认知和衰老相关疾病中找到适应症。模型酵母酿酒酵母对于发现 TORC1 途径和阐明雷帕霉素作用机制至关重要。酵母中这条通路的表征正在继续揭示TORC1信号传导的基本方面，这可以促进哺乳动物中的类似研究并导致改进的抗癌疗法。