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

• 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
• 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

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）的靶标在无处不在的保守信号转导级联中起着重要的作用，该级联反应于营养和生长因子线索，以控制细胞的生长和增殖。 Torc1级联反应的失调导致多种类型的人类恶性肿瘤。中央TORC1成员是Tor蛋白激酶，在酵母糖粉酿酒酵母中发现，这是一种模型系统，对于阐明Torc1信号级联的模型系统至关重要。雷帕霉素基于其有效的抗增生活性，在包括免疫抑制，癌症化学疗法和介入心脏病的几个临床区域使用。尽管进行了大量研究，但TORC1途径仍然部分表征。我们发现了内膜囊泡运输系统在调节酵母中Torc1信号中的意外作用。蛋白质复合物的突变在囊泡运输和蛋白质排序中与非必需的TOR1激酶的突变结合使用，使细胞不可或缺或严重生长受损。我们证明，需要啤酒花复合物为有效的TORC1信号传导和正常表达TORC1-GORED基因提供氨基酸稳态。这些研究还揭示了雷帕霉素作用机理中的一个新方面：雷帕霉素绕过囊泡运输事件，以激活TORC1控制的反式激活剂。此外，我们表明自我复合物（EGOC）折衷的Torc1信号传导以及EGOC和TORC1活性都是最佳细胞生长所必需的。 EGOC具有进化保守的氨基酸敏感的GTPase亚基和这些（GTR1,2和RAGA-D蛋白）的直系同源物，可介导酵母，昆虫和哺乳动物细胞中的Torc1激活。但是，氨基酸传感器的身份和氨基酸激活EGOC GTPase的基本机制尚不清楚。 有趣的是，TORC1和EGOC共定位于内膜，包括内体和液泡，以及液泡氨基酸转运蛋白。该提案的目的是：1）阐明内膜系统使TORC1信号传导的作用和潜在机制，以及2）确定在哺乳动物中保守的液泡氨基酸转运蛋白是否被整合到凸出氨基酸信号的分子级联膜级别中，以唤起Torc1 torc1 torc1。我们的工作模型是，内膜网络提供了一个平台，以促进激活和启用TORC1信号传导的分子相互作用。与酵母菌Torc1相似，哺乳动物TORC1也位于内膜，尤其是溶酶体，这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可以直接推断到哺乳动物模型的基本，保守的TORC1信号转导方面，并指导人类癌症和其他疾病中某些TORC1途径缺陷的药理干预。 公共卫生相关性：雷帕霉素敏感的torc1是进化保存的信号级联的核心组成部分，该级联反应于营养和生长因子，可调节细胞的生长和增殖。 MTORC1信号的缺陷导致癌症和其他人类疾病。雷帕霉素及其类似物是作为治疗多种恶性肿瘤的治疗剂而开发的，还可以发现与认知和衰老相关疾病的指示。酿酒酵母模型对于发现TORC1途径和阐明雷帕霉素作用机理至关重要。该途径在酵母中的表征继续揭示了TORC1信号的基本方面，这些方面可能会促进哺乳动物中的类似研究并导致改善的抗癌疗法。