Lysosomal cholesterol-dependent anabolic regulation

溶酶体胆固醇依赖性合成代谢调节

基本信息

批准号：
10589129
负责人：
Ken Inoki
金额：
$ 52.17万
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：
2022
资助国家：
美国
起止时间：
2022-04-01 至 2026-01-31
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10589129
关键词：
Ablation Acids Adipose tissue Adult Amino Acids Autophagocytosis Binding Binding Proteins Brain Brain region Catabolic Process Cell membrane Cells Cholesterol Complex Cues Data Development Diabetes Mellitus Disease Dissociation Eating Event FRAP1 gene GTPase-Activating Proteins Genetic Growth Growth Factor Guanine Guanine Nucleotide Exchange Factors Guanosine Triphosphate Phosphohydrolases Health Heterozygote High Fat Diet Human In Vitro Knockout Mice Link Lipids Lipolysis Lysosomal Storage Diseases Lysosomes Malignant Neoplasms Membrane Membrane Lipids Membrane Microdomains Metabolic Metabolic Diseases Modeling Molecular Monomeric GTP-Binding Proteins Mus Mutation NPC1 gene Neurodegenerative Disorders Niemann-Pick Diseases Obesity Pathologic Pathway interactions Phenotype Phosphatidylinositol 4,5-Diphosphate Physiological Play Process Protein Kinase Proteins Regulation Resistance Role Signal Transduction Signaling Protein Sirolimus Testing Therapeutic Thinness Tissues Weight Gain cell growth cell growth regulation cholesterol-binding protein design diet-induced obesity experimental study in vitro activity in vivo inhibitor insulin sensitivity lipid metabolism male methyl-beta-cyclodextrin mouse model nucleotide metabolism organ growth protein complex recruit

项目摘要

Project Summary mTORC1 stimulates cell and organ growth mainly by stimulating cellular anabolic processes, including protein, lipid, and nucleotide synthesis, and inhibiting catabolic processes such as autophagy. Aberrant activation of mTORC1 signaling has been linked to many human health problems, including cancer, neurodegenerative diseases, and metabolic disorders such as obesity and diabetes. The activity of mTORC1 is tightly regulated by growth factors and multiple cellular metabolic cues such as amino acids, where amino acids recruit mTORC1 to the lysosome through Rag small GTPases activation, a key process for mTORC1 activation. Although recent studies have revealed the molecular mechanisms by which amino acids induce the lysosomal mTORC1 localization and its activation via Rag GTPases, it has just begun to uncover how cellular lipids such as cholesterol also regulate the activity of mTORC1. A recent study demonstrated that, in addition to amino acids, lysosomal cholesterol also plays a key role in enhancing the activity of Rag GTPases through SLC38A9, the guanine exchange factor for RagA/B. We discovered that BASP1 (Brain abundant signal membrane attached signal protein 1), a known lipid raft cholesterol/PIP2-binding protein, functions as a key stimulator of mTORC1 activity. Mechanistically, BASP1 expresses on the lysosome in a manner dependent on cellular cholesterol and interacts with and inhibits GATOR1, the GTPase activating protein complex for RagA/B, thereby stimulating cellular mTORC1 activity. In addition, ablation of BASP1 largely diminished aberrant mTORC1 activation in cells lacking functional Niemann-Pick Disease, Type C1 (NPC1), a lysosomal cholesterol exporter. Basp1 hypomorphic mice display a reduced developmental growth, reminiscent of mTOR hypomorphic mice or mice treated with the mTORC1 inhibitor, rapamycin. Interestingly, while adult Basp1 hypomorphs show higher insulin sensitivity, they display resistance to diet-induced obesity. We propose that BASP1 plays a crucial role in stimulating cellular mTORC1 activity to induce anabolic processes by sensing lysosomal membrane cholesterol or other lipids and contribute to developmental growth and diet-induced obesity. This proposal will elucidate the molecular mechanisms by which lysosomal lipids enhance BASP1 activity and how BASP1 inhibits GATOR1 activity and investigates the pathophysiological importance of BASP1 in developing metabolic disorders in mice models. Completing this project establishes the role of the NPC1-BASP1-GATOR1-mTORC1 pathway in the regulation of cellular anabolic actions and should yield valuable information to set additional experiments to explore this new branch of lysosomal-oriented mTORC1 regulatory signaling in metabolic disorders and other mTORC1-related human health problems, including neurodegenerative disease, lysosomal storage disorders, and cancer.

项目概要 mTORC1 主要通过刺激细胞合成代谢过程来刺激细胞和器官生长，包括蛋白质、脂质和核苷酸合成，并抑制分解代谢过程，例如自噬。异常激活 mTORC1 信号传导与许多人类健康问题有关，包括癌症、神经退行性疾病疾病和代谢紊乱，例如肥胖和糖尿病。 mTORC1 的活性受到严格调控生长因子和多种细胞代谢线索，例如氨基酸，其中氨基酸招募 mTORC1 溶酶体通过 Rag 小 GTPases 激活，这是 mTORC1 激活的关键过程。虽然最近研究揭示了氨基酸诱导溶酶体 mTORC1 的分子机制定位及其通过 Rag GTPases 的激活，它刚刚开始揭示细胞脂质如何胆固醇还调节 mTORC1 的活性。最近的一项研究表明，除了氨基酸之外，溶酶体胆固醇还通过 SLC38A9 在增强 Rag GTPases 的活性方面发挥着关键作用。 RagA/B 的鸟嘌呤交换因子。我们发现BASP1（脑丰富信号膜附着信号蛋白 1) 是一种已知的脂筏胆固醇/PIP2 结合蛋白，作为 mTORC1 的关键刺激物发挥作用活动。从机制上讲，BASP1 在溶酶体上的表达方式依赖于细胞胆固醇和与 RagA/B 的 GTPase 激活蛋白复合物 GATOR1 相互作用并抑制 GATOR1，从而刺激细胞 mTORC1 活性。此外，BASP1 的消除很大程度上减少了细胞中 mTORC1 的异常激活缺乏功能性尼曼匹克病 C1 型 (NPC1)，一种溶酶体胆固醇输出蛋白。巴斯普1 低等态小鼠表现出发育生长减慢，让人想起 mTOR 低等态小鼠或小鼠用 mTORC1 抑制剂雷帕霉素治疗。有趣的是，虽然成人 Basp1 亚型表现出更高的胰岛素水平敏感性，它们表现出对饮食引起的肥胖的抵抗力。我们认为 BASP1 在通过感测溶酶体膜胆固醇刺激细胞 mTORC1 活性以诱导合成代谢过程或其他脂质，并有助于发育生长和饮食引起的肥胖。该提案将阐明溶酶体脂质增强 BASP1 活性的分子机制以及 BASP1 如何抑制 GATOR1 活性并研究 BASP1 在小鼠代谢紊乱中的病理生理学重要性模型。完成该项目确立了 NPC1-BASP1-GATOR1-mTORC1 通路在细胞合成代谢作用的调节，并且应该产生有价值的信息来进行额外的实验探索代谢紊乱和其他疾病中溶酶体导向的 mTORC1 调节信号的新分支 mTORC1相关的人类健康问题，包括神经退行性疾病、溶酶体贮积症、和癌症。