Regulation of mTOR complexes (mTORCs) by directly acting kinases

通过直接作用的激酶调节 mTOR 复合物 (mTORC)

基本信息

批准号：
8894499
负责人：
Diane C. Fingar
金额：
$ 33.71万
依托单位：
UNIVERSITY OF MICHIGAN AT ANN ARBOR
依托单位国家：
美国
项目类别：
财政年份：
2014
资助国家：
美国
起止时间：
2014-07-18 至 2018-04-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8894499
关键词：
5&apos -AMP-activated protein kinase Actins Acute Anabolism Apoptosis Biochemical Biology Cardiovascular Diseases Catalytic Domain Cell Proliferation Cell Survival Cell physiology Cells Chronic Clinical Management Complex Cultured Cells Cytoskeleton Data Development Diabetes Mellitus Disease EGF gene Energy Metabolism Event Fibroblasts Future Growth Factor Health Homeostasis Host Defense Immune Immunosuppression In Vitro Infection Inflammatory Insulin Resistance Interferons Knowledge Laboratories Link Malignant Neoplasms Mediating Metabolism Mitochondria Molecular Mus Natural Immunity Obesity Pathway interactions Phospho-Specific Antibodies Phosphorylation Phosphotransferases Physiological Physiology Play Process Production Proteins Regulation Renal carcinoma Research Role Signal Transduction Signaling Molecule Sirolimus Site Stimulus Stress TBK1 gene Therapeutic Tumor Promoters Tumor Suppressor Proteins Work cancer cell cell growth cell growth regulation defense response design energy balance human disease immune function in vivo inhibitor/antagonist macrophage microbial novel prevent response sensor therapeutic target tool tumorigenesis

项目摘要

DESCRIPTION (provided by applicant): The mechanistic target of rapamycin (mTOR) responds to diverse environmental signals to control essential cellular functions, playing critical roles in processes related to metabolism, tumorigenesis, and immune function. mTOR constitutes the catalytic core of two functionally distinct signaling complexes, mTORC1 and mTORC2: mTORC1 promotes anabolic cellular processes; while significantly less well understood; mTORC2 promotes cell survival and modulates the actin cytoskeleton. Despite the clear physiologic and therapeutic importance of mTOR, fundamental gaps exist in our knowledge regarding cellular mTOR regulation, especially with regard to the molecular pathways that regulate mTOR activity. Exciting recent work from our laboratory revealed that mTOR phosphorylation plays an important and previously unrecognized role in mTORC1 function. Using phospho specific antibodies and an in vitro kinome screen as tools, we discovered that TBK1/IKKe (kinases that promote innate immune signaling and the host defense response) and AMPK (a kinase that responds to energetic stress) phosphorylate mTOR on distinct sites. Importantly, these phosphorylation events occur in response to physiological signals in cultured cells and in vivo (i.e. mice). Our preliminary data indicate that TBK1/IKKe-mediated phosphorylation of mTOR S2159 promotes mTORC1 signaling while AMPK promotes mTORC2 signaling in response to acute energetic stress. In this application we propose to elucidate roles for these physiologically and pathologically significant signaling molecules in the cellular regulation and function of mTOR. In Aim 1, we investigate the hypothesis that TBK1 and IKKe act directly on mTORC1 to promote growth factor responses and innate immunity; in Aim 2, we investigate the hypothesis that AMPK acts directly on mTORC2 to suppress apoptosis and enhance mitochondrial function to maintain energy homeostasis during acute energetic stress. Emerging data suggest that TBK1/IKKe contribute to chronic inflammatory diseases and obesity-linked insulin resistance; moreover, cancer cells hijack TBK1/IKKe to promote tumorigenesis. As cellular TBK1/IKKe signaling networks remain poorly understood, this research focused on the TBK1/IKKe-mTORC1 axis has potential to impact the future clinical management of chronic inflammatory diseases and cancer. In response to insufficient ATP levels, AMPK stimulates energy producing catabolic and suppresses energy consuming anabolic pathways. This research focused on the AMPK-mTORC2 axis may explain in part the emerging paradox that AMPK can act as a tumor suppressor (by inhibiting cellular anabolism) and a tumor promoter (by inhibiting apoptosis), depending on cellular context. This work will unveil novel regulatory paradigms that directly impact mTOR and will reveal previously unknown links between mTOR and the processes controlled by these kinases, including cell survival, cell metabolism, tumorigenesis, and innate immunity. As the signals that regulate mTORC2 remain virtually unknown, the identification of AMPK as an mTORC2 activator represents a particularly important milestone.

描述（由申请人提供）：雷帕霉素（mTOR）的机制靶点响应不同的环境信号来控制基本的细胞功能，发挥着关键作用在与代谢、肿瘤发生和免疫功能相关的过程中发挥作用。 mTOR 构成两个功能不同的信号复合物 mTORC1 和 mTORC2 的催化核心：mTORC1 促进合成代谢细胞过程；而人们对它的了解却少得多； mTORC2 促进细胞存活并调节肌动蛋白细胞骨架。尽管 mTOR 具有明确的生理和治疗重要性，但我们对细胞 mTOR 调节的认识存在根本差距，特别是在调节 mTOR 活性的分子途径方面。我们实验室最近令人兴奋的工作表明，mTOR 磷酸化在 mTORC1 功能中发挥着重要且以前未被认识到的作用。使用磷酸特异性抗体和体外激酶组筛选作为工具，我们发现 TBK1/IKKe（促进先天免疫信号传导和宿主防御反应的激酶）和 AMPK（响应能量应激的激酶）在不同位点磷酸化 mTOR。重要的是，这些磷酸化事件是响应培养细胞和体内（即小鼠）的生理信号而发生的。我们的初步数据表明 TBK1/IKKe 介导的 mTOR S2159 磷酸化可促进 mTORC1 信号传导，而 AMPK 则可促进 mTORC2 信号传导以响应急性能量应激。在此应用中，我们建议阐明这些生理学和病理学上重要的信号分子在 mTOR 的细胞调节和功能中的作用。在目标 1 中，我们研究了 TBK1 和 IKKe 直接作用于 mTORC1 以促进生长因子反应和先天免疫的假设；在目标 2 中，我们研究了以下假设：AMPK 直接作用于 mTORC2 以抑制细胞凋亡并增强线粒体功能，从而在急性能量应激期间维持能量稳态。新数据表明 TBK1/IKKe 会导致慢性炎症性疾病和肥胖相关的胰岛素抵抗；此外，癌细胞劫持 TBK1/IKKe 来促进肿瘤发生。由于细胞 TBK1/IKKe 信号网络仍然知之甚少，这项专注于 TBK1/IKKe-mTORC1 轴的研究有可能影响慢性炎症性疾病和癌症的未来临床管理。为了应对 ATP 水平不足，AMPK 刺激产生能量的分解代谢并抑制能量消耗的合成代谢途径。这项专注于 AMPK-mTORC2 轴的研究可能部分解释了新出现的悖论，即 AMPK 可以根据细胞环境充当肿瘤抑制因子（通过抑制细胞合成代谢）和肿瘤促进剂（通过抑制细胞凋亡）。这项工作将揭示直接影响 mTOR 的新颖调控范式，并将揭示 mTOR 与这些激酶控制的过程之间以前未知的联系，包括细胞存活、细胞代谢、肿瘤发生和先天免疫。由于调节 mTORC2 的信号实际上仍然未知，因此将 AMPK 鉴定为 mTORC2 激活剂代表着一个特别重要的里程碑。