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Liu X, Guo B, Li Q, Nie J. mTOR in metabolic homeostasis and disease. Exp Cell Res 2024; 441:114173. [PMID: 39047807 DOI: 10.1016/j.yexcr.2024.114173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2023] [Revised: 07/20/2024] [Accepted: 07/21/2024] [Indexed: 07/27/2024]
Abstract
The ability to maintain cellular metabolic homeostasis is critical to life, in which mTOR plays an important role. This kinase integrates upstream nutrient signals and performs essential functions in physiology and metabolism by increasing metabolism and suppressing autophagy. Thus, dysregulation of mTOR activity leads to diseases, especially metabolic diseases such as cancer, type 2 diabetes and neurological disorders. Therefore, inhibition of overactivated mTOR becomes a rational approach to treat a variety of metabolic diseases. In this review, we discuss how mTOR responds to upstream signals and how mTOR regulates metabolic processes, including protein, nucleic acid, and lipid metabolism. Furthermore, we discuss the possible causes and consequences of dysregulated mTOR signaling activity, and summarize relevant applications, such as inhibition of mTOR activity to treat these diseases. This review will advance our comprehensive knowledge of the association between mTOR and metabolic homeostasis, which has significant ramifications for human health.
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Affiliation(s)
- Xuejia Liu
- Key Laboratory of Basic Pharmacology of Ministry of Education and Joint International Research Laboratory of Ethnomedicine of Ministry of Education, Zunyi Medical University, Zunyi, China
| | - Bin Guo
- Key Laboratory of Basic Pharmacology of Ministry of Education and Joint International Research Laboratory of Ethnomedicine of Ministry of Education, Zunyi Medical University, Zunyi, China
| | - Qiye Li
- Key Laboratory of Basic Pharmacology of Ministry of Education and Joint International Research Laboratory of Ethnomedicine of Ministry of Education, Zunyi Medical University, Zunyi, China
| | - Jing Nie
- Key Laboratory of Basic Pharmacology of Ministry of Education and Joint International Research Laboratory of Ethnomedicine of Ministry of Education, Zunyi Medical University, Zunyi, China.
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2
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Cameron CM, Raghu V, Richardson B, Zagore LL, Tamilselvan B, Golden J, Cartwright M, Schoen RE, Finn OJ, Benos PV, Cameron MJ. Pre-vaccination transcriptomic profiles of immune responders to the MUC1 peptide vaccine for colon cancer prevention. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2024:2024.05.09.24305336. [PMID: 38766010 PMCID: PMC11100921 DOI: 10.1101/2024.05.09.24305336] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Self-antigens abnormally expressed on tumors, such as MUC1, have been targeted by therapeutic cancer vaccines. We recently assessed in two clinical trials in a preventative setting whether immunity induced with a MUC1 peptide vaccine could reduce high colon cancer risk in individuals with a history of premalignant colon adenomas. In both trials, there were immune responders and non-responders to the vaccine. Here we used PBMC pre-vaccination and 2 weeks after the first vaccine of responders and non-responders selected from both trials to identify early biomarkers of immune response involved in long-term memory generation and prevention of adenoma recurrence. We performed flow cytometry, phosflow, and differential gene expression analyses on PBMCs collected from MUC1 vaccine responders and non-responders pre-vaccination and two weeks after the first of three vaccine doses. MUC1 vaccine responders had higher frequencies of CD4 cells pre-vaccination, increased expression of CD40L on CD8 and CD4 T-cells, and a greater increase in ICOS expression on CD8 T-cells. Differential gene expression analysis revealed that iCOSL, PI3K AKT MTOR, and B-cell signaling pathways are activated early in response to the MUC1 vaccine. We identified six specific transcripts involved in elevated antigen presentation, B-cell activation, and NF-kB1 activation that were directly linked to finding antibody response at week 12. Finally, a model using these transcripts was able to predict non-responders with accuracy. These findings suggest that individuals who can be predicted to respond to the MUC1 vaccine, and potentially other vaccines, have greater readiness in all immune compartments to present and respond to antigens. Predictive biomarkers of MUC1 vaccine response may lead to more effective vaccines tailored to individuals with high risk for cancer but with varying immune fitness.
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Affiliation(s)
- Cheryl M Cameron
- Department of Nutrition, Case Western Reserve University, Cleveland, OH
| | - Vineet Raghu
- Department of Computer Science, University of Pittsburgh, Pittsburgh, PA
- Massachusetts General Hospital, Harvard Medical School, Cambridge, MA
| | - Brian Richardson
- Department of Nutrition, Case Western Reserve University, Cleveland, OH
- Department of Population and Quantitative Health Sciences, Case Western Reserve University, Cleveland, OH
| | - Leah L Zagore
- Department of Population and Quantitative Health Sciences, Case Western Reserve University, Cleveland, OH
| | | | - Jackelyn Golden
- Department of Population and Quantitative Health Sciences, Case Western Reserve University, Cleveland, OH
| | - Michael Cartwright
- Department of Population and Quantitative Health Sciences, Case Western Reserve University, Cleveland, OH
| | - Robert E Schoen
- Division of Gastroenterology, Hepatology and Nutrition, University of Pittsburgh, Pittsburgh, PA
| | - Olivera J Finn
- Department of Immunology, University of Pittsburgh, Pittsburgh, PA
| | - Panayiotis V Benos
- Department of Epidemiology, University of Florida, Gainesville, FL
- Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh, PA
| | - Mark J Cameron
- Department of Population and Quantitative Health Sciences, Case Western Reserve University, Cleveland, OH
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3
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Muller M, Bélanger J, Hadj-Aissa I, Zhang C, Sephton CF, Dutchak PA. GATOR1 Mutations Impair PI3 Kinase-Dependent Growth Factor Signaling Regulation of mTORC1. Int J Mol Sci 2024; 25:2068. [PMID: 38396745 PMCID: PMC10889792 DOI: 10.3390/ijms25042068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Revised: 02/05/2024] [Accepted: 02/07/2024] [Indexed: 02/25/2024] Open
Abstract
GATOR1 (GAP Activity TOward Rag 1) is an evolutionarily conserved GTPase-activating protein complex that controls the activity of mTORC1 (mammalian Target Of Rapamycin Complex 1) in response to amino acid availability in cells. Genetic mutations in the GATOR1 subunits, NPRL2 (nitrogen permease regulator-like 2), NPRL3 (nitrogen permease regulator-like 3), and DEPDC5 (DEP domain containing 5), have been associated with epilepsy in humans; however, the specific effects of these mutations on GATOR1 function and mTORC1 regulation are not well understood. Herein, we report that epilepsy-linked mutations in the NPRL2 subunit of GATOR1, NPRL2-L105P, -T110S, and -D214H, increase basal mTORC1 signal transduction in cells. Notably, we show that NPRL2-L105P is a loss-of-function mutation that disrupts protein interactions with NPRL3 and DEPDC5, impairing GATOR1 complex assembly and resulting in high mTORC1 activity even under conditions of amino acid deprivation. Furthermore, our studies reveal that the GATOR1 complex is necessary for the rapid and robust inhibition of mTORC1 in response to growth factor withdrawal or pharmacological inhibition of phosphatidylinositol-3 kinase (PI3K). In the absence of the GATOR1 complex, cells are refractory to PI3K-dependent inhibition of mTORC1, permitting sustained translation and restricting the nuclear localization of TFEB, a transcription factor regulated by mTORC1. Collectively, our results show that epilepsy-linked mutations in NPRL2 can block GATOR1 complex assembly and restrict the appropriate regulation of mTORC1 by canonical PI3K-dependent growth factor signaling in the presence or absence of amino acids.
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Affiliation(s)
| | | | | | | | | | - Paul A. Dutchak
- Department of Psychiatry and Neuroscience, CERVO Brain Research Centre, Université Laval, Quebec City, QC G1J 2G3, Canada
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4
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Ivanova I, Shen K. Structures and Functions of the Human GATOR1 Complex. Subcell Biochem 2024; 104:269-294. [PMID: 38963491 DOI: 10.1007/978-3-031-58843-3_12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/05/2024]
Abstract
Eukaryotic cells coordinate available nutrients with their growth through the mechanistic target of rapamycin complex 1 (mTORC1) pathway, in which numerous evolutionarily conserved protein complexes survey and transmit nutrient inputs toward mTORC1. mTORC1 integrates these inputs and activates downstream anabolic or catabolic programs that are in tune with cellular needs, effectively maintaining metabolic homeostasis. The GAP activity toward Rags-1 (GATOR1) protein complex is a critical negative regulator of the mTORC1 pathway and, in the absence of amino acid inputs, is activated to turn off mTORC1 signaling. GATOR1-mediated inhibition of mTORC1 signaling is tightly regulated by an ensemble of protein complexes that antagonize or promote its activity in response to the cellular nutrient environment. Structural, biochemical, and biophysical studies of the GATOR1 complex and its interactors have advanced our understanding of how it regulates cellular metabolism when amino acids are limited. Here, we review the current research with a focus on GATOR1 structure, its enzymatic mechanism, and the growing group of proteins that regulate its activity. Finally, we discuss the implication of GATOR1 dysregulation in physiology and human diseases.
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Affiliation(s)
- Ilina Ivanova
- Program in Molecular Medicine, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Kuang Shen
- Program in Molecular Medicine, University of Massachusetts Chan Medical School, Worcester, MA, USA.
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Chan Medical School, Worcester, MA, USA.
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5
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Jiang C, Liu J, He S, Xu W, Huang R, Pan W, Li X, Dai X, Guo J, Zhang T, Inuzuka H, Wang P, Asara JM, Xiao J, Wei W. PRMT1 orchestrates with SAMTOR to govern mTORC1 methionine sensing via Arg-methylation of NPRL2. Cell Metab 2023; 35:2183-2199.e7. [PMID: 38006878 PMCID: PMC11192564 DOI: 10.1016/j.cmet.2023.11.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Revised: 09/22/2023] [Accepted: 11/01/2023] [Indexed: 11/27/2023]
Abstract
Methionine is an essential branch of diverse nutrient inputs that dictate mTORC1 activation. In the absence of methionine, SAMTOR binds to GATOR1 and inhibits mTORC1 signaling. However, how mTORC1 is activated upon methionine stimulation remains largely elusive. Here, we report that PRMT1 senses methionine/SAM by utilizing SAM as a cofactor for an enzymatic activity-based regulation of mTORC1 signaling. Under methionine-sufficient conditions, elevated cytosolic SAM releases SAMTOR from GATOR1, which confers the association of PRMT1 with GATOR1. Subsequently, SAM-loaded PRMT1 methylates NPRL2, the catalytic subunit of GATOR1, thereby suppressing its GAP activity and leading to mTORC1 activation. Notably, genetic or pharmacological inhibition of PRMT1 impedes hepatic methionine sensing by mTORC1 and improves insulin sensitivity in aged mice, establishing the role of PRMT1-mediated methionine sensing at physiological levels. Thus, PRMT1 coordinates with SAMTOR to form the methionine-sensing apparatus of mTORC1 signaling.
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Affiliation(s)
- Cong Jiang
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02115, USA; Joint Research Center for Musculoskeletal Tumor of Shanghai Changzheng Hospital and University of Shanghai for Science and Technology, Spinal Tumor Center, Department of Orthopedic Oncology, Shanghai Changzheng Hospital, Shanghai 200003, China; Tongji University Cancer Center, Shanghai Tenth People's Hospital, School of Medicine, Tongji University, Shanghai 200092, China
| | - Jing Liu
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02115, USA
| | - Shaohui He
- Joint Research Center for Musculoskeletal Tumor of Shanghai Changzheng Hospital and University of Shanghai for Science and Technology, Spinal Tumor Center, Department of Orthopedic Oncology, Shanghai Changzheng Hospital, Shanghai 200003, China
| | - Wei Xu
- Joint Research Center for Musculoskeletal Tumor of Shanghai Changzheng Hospital and University of Shanghai for Science and Technology, Spinal Tumor Center, Department of Orthopedic Oncology, Shanghai Changzheng Hospital, Shanghai 200003, China
| | - Runzhi Huang
- Tongji University Cancer Center, Shanghai Tenth People's Hospital, School of Medicine, Tongji University, Shanghai 200092, China
| | - Weijuan Pan
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai 200241, China
| | - Xiaolong Li
- Ragon Institute of MGH, MIT and Harvard, Cambridge, MA 02139, USA
| | - Xiaoming Dai
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02115, USA
| | - Jianping Guo
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02115, USA
| | - Tao Zhang
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02115, USA
| | - Hiroyuki Inuzuka
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02115, USA
| | - Ping Wang
- Tongji University Cancer Center, Shanghai Tenth People's Hospital, School of Medicine, Tongji University, Shanghai 200092, China
| | - John M Asara
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02115, USA
| | - Jianru Xiao
- Joint Research Center for Musculoskeletal Tumor of Shanghai Changzheng Hospital and University of Shanghai for Science and Technology, Spinal Tumor Center, Department of Orthopedic Oncology, Shanghai Changzheng Hospital, Shanghai 200003, China.
| | - Wenyi Wei
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02115, USA.
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Goul C, Peruzzo R, Zoncu R. The molecular basis of nutrient sensing and signalling by mTORC1 in metabolism regulation and disease. Nat Rev Mol Cell Biol 2023; 24:857-875. [PMID: 37612414 DOI: 10.1038/s41580-023-00641-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/06/2023] [Indexed: 08/25/2023]
Abstract
The Ser/Thr kinase mechanistic target of rapamycin (mTOR) is a central regulator of cellular metabolism. As part of mTOR complex 1 (mTORC1), mTOR integrates signals such as the levels of nutrients, growth factors, energy sources and oxygen, and triggers responses that either boost anabolism or suppress catabolism. mTORC1 signalling has wide-ranging consequences for the growth and homeostasis of key tissues and organs, and its dysregulated activity promotes cancer, type 2 diabetes, neurodegeneration and other age-related disorders. How mTORC1 integrates numerous upstream cues and translates them into specific downstream responses is an outstanding question with major implications for our understanding of physiology and disease mechanisms. In this Review, we discuss recent structural and functional insights into the molecular architecture of mTORC1 and its lysosomal partners, which have greatly increased our mechanistic understanding of nutrient-dependent mTORC1 regulation. We also discuss the emerging involvement of aberrant nutrient-mTORC1 signalling in multiple diseases.
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Affiliation(s)
- Claire Goul
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
| | - Roberta Peruzzo
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
| | - Roberto Zoncu
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA.
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7
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Tettoni SD, Egri SB, Doxsey DD, Veinotte K, Ouch C, Chang JY, Song K, Xu C, Shen K. Structure of the Schizosaccharomyces pombe Gtr-Lam complex reveals evolutionary divergence of mTORC1-dependent amino acid sensing. Structure 2023; 31:1065-1076.e5. [PMID: 37453417 PMCID: PMC10529327 DOI: 10.1016/j.str.2023.06.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Revised: 05/14/2023] [Accepted: 06/19/2023] [Indexed: 07/18/2023]
Abstract
mTORC1 is a protein kinase complex that controls cellular growth in response to nutrient availability. Amino acid signals are transmitted toward mTORC1 via the Rag/Gtr GTPases and their upstream regulators. An important regulator is LAMTOR, which localizes Rag/Gtr on the lysosomal/vacuole membrane. In human cells, LAMTOR consists of five subunits, but in yeast, only three or four. Currently, it is not known how variation of the subunit stoichiometry may affect its structural organization and biochemical properties. Here, we report a 3.1 Å-resolution structural model of the Gtr-Lam complex in Schizosaccharomyces pombe. We found that SpGtr shares conserved architecture as HsRag, but the intersubunit communication that coordinates nucleotide loading on the two subunits differs. In contrast, SpLam contains distinctive structural features, but its GTP-specific GEF activity toward SpGtr is evolutionarily conserved. Our results revealed unique evolutionary paths of the protein components of the mTORC1 pathway.
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Affiliation(s)
- Steven D Tettoni
- Program in Molecular Medicine, University of Massachusetts Chan Medical School, 373 Plantation Street, Worcester, MA 01605, USA
| | - Shawn B Egri
- Program in Molecular Medicine, University of Massachusetts Chan Medical School, 373 Plantation Street, Worcester, MA 01605, USA
| | - Dylan D Doxsey
- Program in Molecular Medicine, University of Massachusetts Chan Medical School, 373 Plantation Street, Worcester, MA 01605, USA
| | - Kristen Veinotte
- Program in Molecular Medicine, University of Massachusetts Chan Medical School, 373 Plantation Street, Worcester, MA 01605, USA
| | - Christna Ouch
- Department of Biochemistry & Molecular Biotechnology, University of Massachusetts Chan Medical School, 364 Plantation Street, Worcester, MA 01605, USA
| | - Jeng-Yih Chang
- Department of Biochemistry & Molecular Biotechnology, University of Massachusetts Chan Medical School, 364 Plantation Street, Worcester, MA 01605, USA
| | - Kangkang Song
- Department of Biochemistry & Molecular Biotechnology, University of Massachusetts Chan Medical School, 364 Plantation Street, Worcester, MA 01605, USA
| | - Chen Xu
- Department of Biochemistry & Molecular Biotechnology, University of Massachusetts Chan Medical School, 364 Plantation Street, Worcester, MA 01605, USA
| | - Kuang Shen
- Program in Molecular Medicine, University of Massachusetts Chan Medical School, 373 Plantation Street, Worcester, MA 01605, USA; Department of Biochemistry & Molecular Biotechnology, University of Massachusetts Chan Medical School, 364 Plantation Street, Worcester, MA 01605, USA.
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8
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Doxsey DD, Tettoni SD, Egri SB, Shen K. Redundant electrostatic interactions between GATOR1 and the Rag GTPase heterodimer drive efficient amino acid sensing in human cells. J Biol Chem 2023; 299:104880. [PMID: 37269949 PMCID: PMC10316081 DOI: 10.1016/j.jbc.2023.104880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 05/23/2023] [Accepted: 05/25/2023] [Indexed: 06/05/2023] Open
Abstract
Cells need to coordinate nutrient availability with their growth and proliferation. In eukaryotic cells, this coordination is mediated by the mechanistic target of the rapamycin complex 1 (mTORC1) pathway. mTORC1 activation is regulated by two GTPase units, the Rag GTPase heterodimer and the Rheb GTPase. The RagA-RagC heterodimer controls the subcellular localization of mTORC1, and its nucleotide loading states are strictly controlled by upstream regulators including amino acid sensors. A critical negative regulator of the Rag GTPase heterodimer is GATOR1. In the absence of amino acids, GATOR1 stimulates GTP hydrolysis by the RagA subunit to turn off mTORC1 signaling. Despite the enzymatic specificity of GATOR1 to RagA, a recent cryo-EM structural model of the human GATOR1-Rag-Ragulator complex reveals an unexpected interface between Depdc5, a subunit of GATOR1, and RagC. Currently, there is no functional characterization of this interface, nor do we know its biological relevance. Here, combining structure-function analysis, enzymatic kinetic measurements, and cell-based signaling assays, we identified a critical electrostatic interaction between Depdc5 and RagC. This interaction is mediated by the positively charged Arg-1407 residue on Depdc5 and a patch of negatively charged residues on the lateral side of RagC. Abrogating this interaction impairs the GAP activity of GATOR1 and cellular response to amino acid withdrawal. Our results reveal how GATOR1 coordinates the nucleotide loading states of the Rag GTPase heterodimer, and thus precisely controls cellular behavior in the absence of amino acids.
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Affiliation(s)
- Dylan D Doxsey
- Program in Molecular Medicine, University of Massachusetts Chan Medical School, Worcester, Massachusetts, USA
| | - Steven D Tettoni
- Program in Molecular Medicine, University of Massachusetts Chan Medical School, Worcester, Massachusetts, USA
| | - Shawn B Egri
- Program in Molecular Medicine, University of Massachusetts Chan Medical School, Worcester, Massachusetts, USA
| | - Kuang Shen
- Program in Molecular Medicine, University of Massachusetts Chan Medical School, Worcester, Massachusetts, USA; Department of Biochemistry & Molecular Pharmacology, University of Massachusetts Chan Medical School, Worcester, Massachusetts, USA.
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Cui Z, Joiner AMN, Jansen RM, Hurley JH. Amino acid sensing and lysosomal signaling complexes. Curr Opin Struct Biol 2023; 79:102544. [PMID: 36804703 DOI: 10.1016/j.sbi.2023.102544] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Revised: 01/05/2023] [Accepted: 01/11/2023] [Indexed: 02/18/2023]
Abstract
Amino acid pools in the cell are monitored by dedicated sensors, whose structures are now coming into view. The lysosomal Rag GTPases are central to this pathway, and the regulation of their GAP complexes, FLCN-FNIP and GATOR1, have been worked out in detail. For FLCN-FNIP, the entire chain of events from the arginine transporter SLC38A9 to substrate-specific mTORC1 activation has been visualized. The structure GATOR2 has been determined, hinting at an ordering of amino acid signaling across a larger size scale than anticipated. The centerpiece of lysosomal signaling, mTORC1, has been revealed to recognize its substrates by more nuanced and substrate-specific mechanisms than previous appreciated. Beyond the well-studied Rag GTPase and mTORC1 machinery, another lysosomal amino acid sensor/effector system, that of PQLC2 and the C9orf72-containing CSW complex, is coming into structural view. These developments hold promise for further insights into lysosomal physiology and lysosome-centric therapeutics.
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Affiliation(s)
- Zhicheng Cui
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley CA 94720, USA; California Institute for Quantitative Biosciences, University of California, Berkeley, CA, 94720, USA
| | - Aaron M N Joiner
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley CA 94720, USA; California Institute for Quantitative Biosciences, University of California, Berkeley, CA, 94720, USA
| | - Rachel M Jansen
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley CA 94720, USA; California Institute for Quantitative Biosciences, University of California, Berkeley, CA, 94720, USA
| | - James H Hurley
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley CA 94720, USA; California Institute for Quantitative Biosciences, University of California, Berkeley, CA, 94720, USA; Helen Wills Neuroscience Institute, University of California, Berkeley, CA 94720, USA.
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10
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Jansen RM, Hurley JH. Longin domain GAP complexes in nutrient signalling, membrane traffic and neurodegeneration. FEBS Lett 2023; 597:750-761. [PMID: 36367440 PMCID: PMC10050129 DOI: 10.1002/1873-3468.14538] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Revised: 11/01/2022] [Accepted: 11/07/2022] [Indexed: 11/13/2022]
Abstract
Small GTPases act as molecular switches and control numerous cellular processes by their binding and hydrolysis of guanosine triphosphate (GTP). The activity of small GTPases is coordinated by guanine nucleotide exchange factors (GEFs) and GTPase activating proteins (GAPs). Recent structural and functional studies have characterized a subset of GAPs whose catalytic units consist of longin domains. Longin domain containing GAPs regulate small GTPases that facilitate nutrient signalling, autophagy, vesicular trafficking and lysosome homeostasis. All known examples in this GAP family function as part of larger multiprotein complexes. The three characterized mammalian protein complexes in this class are FLCN:FNIP, GATOR1 and C9orf72:SMCR8. Each complex carries out a unique cellular function by regulating distinct small GTPases. In this article, we explore the roles of longin domain GAPs in nutrient sensing, membrane dynamic, vesicular trafficking and disease. Through a structural lens, we examine the mechanism of each longin domain GAP and highlight potential therapeutic applications.
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Affiliation(s)
- Rachel M. Jansen
- Department of Molecular and Cell Biology, University of California Berkeley; Berkeley CA 94720, USA
- California Institute for Quantitative Biosciences, University of California, Berkeley, CA, 94720, USA
| | - James H. Hurley
- Department of Molecular and Cell Biology, University of California Berkeley; Berkeley CA 94720, USA
- California Institute for Quantitative Biosciences, University of California, Berkeley, CA, 94720, USA
- Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA 94720, USA
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11
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Dinet C, Mignot T. Unorthodox regulation of the MglA Ras-like GTPase controlling polarity in Myxococcus xanthus. FEBS Lett 2023; 597:850-864. [PMID: 36520515 DOI: 10.1002/1873-3468.14565] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Revised: 12/09/2022] [Accepted: 12/12/2022] [Indexed: 12/23/2022]
Abstract
Motile cells have developed a large array of molecular machineries to actively change their direction of movement in response to spatial cues from their environment. In this process, small GTPases act as molecular switches and work in tandem with regulators and sensors of their guanine nucleotide status (GAP, GEF, GDI and effectors) to dynamically polarize the cell and regulate its motility. In this review, we focus on Myxococcus xanthus as a model organism to elucidate the function of an atypical small Ras GTPase system in the control of directed cell motility. M. xanthus cells direct their motility by reversing their direction of movement through a mechanism involving the redirection of the motility apparatus to the opposite cell pole. The reversal frequency of moving M. xanthus cells is controlled by modular and interconnected protein networks linking the chemosensory-like frizzy (Frz) pathway - that transmits environmental signals - to the downstream Ras-like Mgl polarity control system - that comprises the Ras-like MglA GTPase protein and its regulators. Here, we discuss how variations in the GTPase interactome landscape underlie single-cell decisions and consequently, multicellular patterns.
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Affiliation(s)
- Céline Dinet
- Laboratoire de Chimie Bactérienne, Institut de Microbiologie de la Méditerranée, CNRS-Aix-Marseille University, France
| | - Tâm Mignot
- Laboratoire de Chimie Bactérienne, Institut de Microbiologie de la Méditerranée, CNRS-Aix-Marseille University, France
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12
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Jiang C, Dai X, He S, Zhou H, Fang L, Guo J, Liu S, Zhang T, Pan W, Yu H, Fu T, Li D, Inuzuka H, Wang P, Xiao J, Wei W. Ring domains are essential for GATOR2-dependent mTORC1 activation. Mol Cell 2023; 83:74-89.e9. [PMID: 36528027 PMCID: PMC11027793 DOI: 10.1016/j.molcel.2022.11.021] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Revised: 09/14/2022] [Accepted: 11/22/2022] [Indexed: 12/23/2022]
Abstract
The GATOR2-GATOR1 signaling axis is essential for amino-acid-dependent mTORC1 activation. However, the molecular function of the GATOR2 complex remains unknown. Here, we report that disruption of the Ring domains of Mios, WDR24, or WDR59 completely impedes amino-acid-mediated mTORC1 activation. Mechanistically, via interacting with Ring domains of WDR59 and WDR24, the Ring domain of Mios acts as a hub to maintain GATOR2 integrity, disruption of which leads to self-ubiquitination of WDR24. Physiologically, leucine stimulation dissociates Sestrin2 from the Ring domain of WDR24 and confers its availability to UBE2D3 and subsequent ubiquitination of NPRL2, contributing to GATOR2-mediated GATOR1 inactivation. As such, WDR24 ablation or Ring deletion prevents mTORC1 activation, leading to severe growth defects and embryonic lethality at E10.5 in mice. Hence, our findings demonstrate that Ring domains are essential for GATOR2 to transmit amino acid availability to mTORC1 and further reveal the essentiality of nutrient sensing during embryonic development.
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Affiliation(s)
- Cong Jiang
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02115, USA
| | - Xiaoming Dai
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02115, USA
| | - Shaohui He
- Joint Research Center for Musculoskeletal Tumor of Shanghai Changzheng Hospital and University of Shanghai for Science and Technology, Spinal Tumor Center, Department of Orthopedic Oncology, Shanghai Changzheng Hospital, Shanghai 200003, China
| | - Hongfei Zhou
- Joint Research Center for Musculoskeletal Tumor of Shanghai Changzheng Hospital and University of Shanghai for Science and Technology, Spinal Tumor Center, Department of Orthopedic Oncology, Shanghai Changzheng Hospital, Shanghai 200003, China
| | - Lan Fang
- Tongji University Cancer Center, Shanghai Tenth People's Hospital, School of Medicine, Tongji University, Shanghai 200092, China
| | - Jianping Guo
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02115, USA
| | - Songlei Liu
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Tao Zhang
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02115, USA
| | - Weijuan Pan
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai 200241, China
| | - Haihong Yu
- Tongji University Cancer Center, Shanghai Tenth People's Hospital, School of Medicine, Tongji University, Shanghai 200092, China
| | - Tianmin Fu
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH 43210, USA
| | - Dali Li
- Shanghai Key Laboratory of Regulatory Biology, Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai 200241, China
| | - Hiroyuki Inuzuka
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02115, USA
| | - Ping Wang
- Tongji University Cancer Center, Shanghai Tenth People's Hospital, School of Medicine, Tongji University, Shanghai 200092, China
| | - Jianru Xiao
- Joint Research Center for Musculoskeletal Tumor of Shanghai Changzheng Hospital and University of Shanghai for Science and Technology, Spinal Tumor Center, Department of Orthopedic Oncology, Shanghai Changzheng Hospital, Shanghai 200003, China.
| | - Wenyi Wei
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02115, USA.
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13
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Tafur L, Hinterndorfer K, Gabus C, Lamanna C, Bergmann A, Sadian Y, Hamdi F, Kyrilis FL, Kastritis PL, Loewith R. Cryo-EM structure of the SEA complex. Nature 2022; 611:399-404. [DOI: 10.1038/s41586-022-05370-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 09/20/2022] [Indexed: 11/09/2022]
Abstract
AbstractThe SEA complex (SEAC) is a growth regulator that acts as a GTPase-activating protein (GAP) towards Gtr1, a Rag GTPase that relays nutrient status to the Target of Rapamycin Complex 1 (TORC1) in yeast1. Functionally, the SEAC has been divided into two subcomplexes: SEACIT, which has GAP activity and inhibits TORC1, and SEACAT, which regulates SEACIT2. This system is conserved in mammals: the GATOR complex, consisting of GATOR1 (SEACIT) and GATOR2 (SEACAT), transmits amino acid3 and glucose4 signals to mTORC1. Despite its importance, the structure of SEAC/GATOR, and thus molecular understanding of its function, is lacking. Here, we solve the cryo-EM structure of the native eight-subunit SEAC. The SEAC has a modular structure in which a COPII-like cage corresponding to SEACAT binds two flexible wings, which correspond to SEACIT. The wings are tethered to the core via Sea3, which forms part of both modules. The GAP mechanism of GATOR1 is conserved in SEACIT, and GAP activity is unaffected by SEACAT in vitro. In vivo, the wings are essential for recruitment of the SEAC to the vacuole, primarily via the EGO complex. Our results indicate that rather than being a direct inhibitor of SEACIT, SEACAT acts as a scaffold for the binding of TORC1 regulators.
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14
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Jansen RM, Peruzzo R, Fromm SA, Yokom AL, Zoncu R, Hurley JH. Structural basis for FLCN RagC GAP activation in MiT-TFE substrate-selective mTORC1 regulation. SCIENCE ADVANCES 2022; 8:eadd2926. [PMID: 36103527 PMCID: PMC9473554 DOI: 10.1126/sciadv.add2926] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Accepted: 07/26/2022] [Indexed: 05/04/2023]
Abstract
The mechanistic target of rapamycin complex 1 (mTORC1) regulates cell growth and catabolism in response to nutrients through phosphorylation of key substrates. The tumor suppressor folliculin (FLCN) is a RagC/D guanosine triphosphatase (GTPase)-activating protein (GAP) that regulates mTORC1 phosphorylation of MiT-TFE transcription factors, controlling lysosome biogenesis and autophagy. We determined the cryo-electron microscopy structure of the active FLCN complex (AFC) containing FLCN, FNIP2, the N-terminal tail of SLC38A9, the RagAGDP:RagCGDP.BeFx- GTPase dimer, and the Ragulator scaffold. Relative to the inactive lysosomal FLCN complex structure, FLCN reorients by 90°, breaks contact with RagA, and makes previously unseen contacts with RagC that position its Arg164 finger for catalysis. Disruption of the AFC-specific interfaces of FLCN and FNIP2 with RagC eliminated GAP activity and led to nuclear retention of TFE3, with no effect on mTORC1 substrates S6K or 4E-BP1. The structure provides a basis for regulation of an mTORC1 substrate-specific pathway and a roadmap to discover MiT-TFE family selective mTORC1 antagonists.
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Affiliation(s)
- Rachel M. Jansen
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
- California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Roberta Peruzzo
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Simon A. Fromm
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
- California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Adam L. Yokom
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
- California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Roberto Zoncu
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
- California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA 94720, USA
| | - James H. Hurley
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
- California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA 94720, USA
- Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA 94720, USA
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15
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Figlia G, Müller S, Hagenston AM, Kleber S, Roiuk M, Quast JP, Ten Bosch N, Carvajal Ibañez D, Mauceri D, Martin-Villalba A, Teleman AA. Brain-enriched RagB isoforms regulate the dynamics of mTORC1 activity through GATOR1 inhibition. Nat Cell Biol 2022; 24:1407-1421. [PMID: 36097071 PMCID: PMC9481464 DOI: 10.1038/s41556-022-00977-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 07/13/2022] [Indexed: 12/26/2022]
Abstract
Mechanistic target of rapamycin complex 1 (mTORC1) senses nutrient availability to appropriately regulate cellular anabolism and catabolism. During nutrient restriction, different organs in an animal do not respond equally, with vital organs being relatively spared. This raises the possibility that mTORC1 is differentially regulated in different cell types, yet little is known about this mechanistically. The Rag GTPases, RagA or RagB bound to RagC or RagD, tether mTORC1 in a nutrient-dependent manner to lysosomes where mTORC1 becomes activated. Although the RagA and B paralogues were assumed to be functionally equivalent, we find here that the RagB isoforms, which are highly expressed in neurons, impart mTORC1 with resistance to nutrient starvation by inhibiting the RagA/B GTPase-activating protein GATOR1. We further show that high expression of RagB isoforms is observed in some tumours, revealing an alternative strategy by which cancer cells can retain elevated mTORC1 upon low nutrient availability.
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Affiliation(s)
- Gianluca Figlia
- Signal Transduction in Cancer and Metabolism, German Cancer Research Center (DKFZ), Heidelberg, Germany.,Heidelberg University, Heidelberg, Germany
| | - Sandra Müller
- Signal Transduction in Cancer and Metabolism, German Cancer Research Center (DKFZ), Heidelberg, Germany.,Heidelberg University, Heidelberg, Germany
| | - Anna M Hagenston
- Department of Neurobiology, Interdisciplinary Center for Neurosciences (IZN), Heidelberg University, INF 366, Heidelberg, Germany
| | - Susanne Kleber
- Molecular Neurobiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Mykola Roiuk
- Signal Transduction in Cancer and Metabolism, German Cancer Research Center (DKFZ), Heidelberg, Germany.,Heidelberg University, Heidelberg, Germany
| | - Jan-Philipp Quast
- Signal Transduction in Cancer and Metabolism, German Cancer Research Center (DKFZ), Heidelberg, Germany.,Heidelberg University, Heidelberg, Germany
| | - Nora Ten Bosch
- Signal Transduction in Cancer and Metabolism, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Damian Carvajal Ibañez
- Heidelberg University, Heidelberg, Germany.,Molecular Neurobiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Daniela Mauceri
- Department of Neurobiology, Interdisciplinary Center for Neurosciences (IZN), Heidelberg University, INF 366, Heidelberg, Germany
| | - Ana Martin-Villalba
- Molecular Neurobiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Aurelio A Teleman
- Signal Transduction in Cancer and Metabolism, German Cancer Research Center (DKFZ), Heidelberg, Germany. .,Heidelberg University, Heidelberg, Germany.
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16
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Gu X, Jouandin P, Lalgudi PV, Binari R, Valenstein ML, Reid MA, Allen AE, Kamitaki N, Locasale JW, Perrimon N, Sabatini DM. Sestrin mediates detection of and adaptation to low-leucine diets in Drosophila. Nature 2022; 608:209-216. [PMID: 35859173 PMCID: PMC10112710 DOI: 10.1038/s41586-022-04960-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Accepted: 06/09/2022] [Indexed: 12/28/2022]
Abstract
Mechanistic target of rapamycin complex 1 (mTORC1) regulates cell growth and metabolism in response to multiple nutrients, including the essential amino acid leucine1. Recent work in cultured mammalian cells established the Sestrins as leucine-binding proteins that inhibit mTORC1 signalling during leucine deprivation2,3, but their role in the organismal response to dietary leucine remains elusive. Here we find that Sestrin-null flies (Sesn-/-) fail to inhibit mTORC1 or activate autophagy after acute leucine starvation and have impaired development and a shortened lifespan on a low-leucine diet. Knock-in flies expressing a leucine-binding-deficient Sestrin mutant (SesnL431E) have reduced, leucine-insensitive mTORC1 activity. Notably, we find that flies can discriminate between food with or without leucine, and preferentially feed and lay progeny on leucine-containing food. This preference depends on Sestrin and its capacity to bind leucine. Leucine regulates mTORC1 activity in glial cells, and knockdown of Sesn in these cells reduces the ability of flies to detect leucine-free food. Thus, nutrient sensing by mTORC1 is necessary for flies not only to adapt to, but also to detect, a diet deficient in an essential nutrient.
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Affiliation(s)
- Xin Gu
- Whitehead Institute for Biomedical Research, Cambridge, MA, USA.
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA.
| | - Patrick Jouandin
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA, USA.
- Howard Hughes Medical Institute, Harvard Medical School, Boston, MA, USA.
| | - Pranav V Lalgudi
- Whitehead Institute for Biomedical Research, Cambridge, MA, USA
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Rich Binari
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
- Howard Hughes Medical Institute, Harvard Medical School, Boston, MA, USA
| | - Max L Valenstein
- Whitehead Institute for Biomedical Research, Cambridge, MA, USA
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Michael A Reid
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, NC, USA
| | - Annamarie E Allen
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, NC, USA
| | - Nolan Kamitaki
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
- Broad Institute of Harvard and Massachusetts Institute of Technology, Cambridge, MA, USA
- Department of Biomedical Informatics, Harvard Medical School, Boston, MA, USA
| | - Jason W Locasale
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, NC, USA
| | - Norbert Perrimon
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA, USA.
- Howard Hughes Medical Institute, Harvard Medical School, Boston, MA, USA.
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17
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Yue S, Li G, He S, Li T. The central role of mTORC1 in amino acid sensing. Cancer Res 2022; 82:2964-2974. [PMID: 35749594 DOI: 10.1158/0008-5472.can-21-4403] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 04/28/2022] [Accepted: 06/17/2022] [Indexed: 11/16/2022]
Abstract
The mechanistic target of rapamycin (mTOR) is a master regulator of cell growth that controls cell homeostasis in response to nutrients, growth factors, and other environmental cues. Recent studies have emphasized the importance of lysosomes as a hub for nutrient sensing, especially amino acid sensing by mTORC1. This review highlights recent advances in understanding the amino acid-mTORC1 signaling axis and the role of mTORC1 in cancer.
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18
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Dentel B, Angeles-Perez L, Ren C, Jakkamsetti V, Holley AJ, Caballero D, Oh E, Gibson J, Pascual JM, Huber KM, Tu BP, Tsai PT. Increased glycine contributes to synaptic dysfunction and early mortality in Nprl2 seizure model. iScience 2022; 25:104334. [PMID: 35602938 PMCID: PMC9118754 DOI: 10.1016/j.isci.2022.104334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Revised: 09/16/2021] [Accepted: 04/26/2022] [Indexed: 10/25/2022] Open
Abstract
Targeted therapies for epilepsies associated with the mTORC1 signaling negative regulator GATOR1 are lacking. NPRL2 is a subunit of the GATOR1 complex and mutations in GATOR1 subunits, including NPRL2, are associated with epilepsy. To delineate the mechanisms underlying NPRL2-related epilepsies, we created a mouse (Mus musculus) model with neocortical loss of Nprl2. Mutant mice have increased mTORC1 signaling and exhibit spontaneous seizures. They also display abnormal synaptic function characterized by increased evoked and spontaneous EPSC and decreased evoked and spontaneous IPSC frequencies, respectively. Proteomic and metabolomics studies of Nprl2 mutants revealed alterations in known epilepsy-implicated proteins and metabolic pathways, including increases in the neurotransmitter, glycine. Furthermore, glycine actions on the NMDA receptor contribute to the electrophysiological and survival phenotypes of these mice. Taken together, in this neuronal Nprl2 model, we delineate underlying molecular, metabolic, and electrophysiological mechanisms contributing to mTORC1-related epilepsy, providing potential therapeutic targets for epilepsy.
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Affiliation(s)
- Brianne Dentel
- Department of Neurology, UT Southwestern Medical Center, Dallas, TX 75235, USA
| | | | - Chongyu Ren
- Department of Neurology, UT Southwestern Medical Center, Dallas, TX 75235, USA
| | - Vikram Jakkamsetti
- Department of Neurology, UT Southwestern Medical Center, Dallas, TX 75235, USA
| | - Andrew J. Holley
- Department of Neuroscience, UT Southwestern Medical Center, Dallas, TX 75235, USA
| | - Daniel Caballero
- Department of Neurology, UT Southwestern Medical Center, Dallas, TX 75235, USA
| | - Emily Oh
- Department of Neurology, UT Southwestern Medical Center, Dallas, TX 75235, USA
| | - Jay Gibson
- Department of Neuroscience, UT Southwestern Medical Center, Dallas, TX 75235, USA
| | - Juan M. Pascual
- Department of Neurology, UT Southwestern Medical Center, Dallas, TX 75235, USA
| | - Kimberly M. Huber
- Department of Neuroscience, UT Southwestern Medical Center, Dallas, TX 75235, USA
| | - Benjamin P. Tu
- Department of Biochemistry, UT Southwestern Medical Center, Dallas, TX 75235, USA
| | - Peter T. Tsai
- Department of Neurology, UT Southwestern Medical Center, Dallas, TX 75235, USA
- Department of Neuroscience, UT Southwestern Medical Center, Dallas, TX 75235, USA
- Departments of Pediatrics and Psychiatry, UT Southwestern Medical Center, Dallas, TX 75235, USA
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19
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Egri SB, Ouch C, Chou HT, Yu Z, Song K, Xu C, Shen K. Cryo-EM structures of the human GATOR1-Rag-Ragulator complex reveal a spatial-constraint regulated GAP mechanism. Mol Cell 2022; 82:1836-1849.e5. [PMID: 35338845 PMCID: PMC9133170 DOI: 10.1016/j.molcel.2022.03.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Revised: 12/09/2021] [Accepted: 02/28/2022] [Indexed: 12/20/2022]
Abstract
mTORC1 controls cellular metabolic processes in response to nutrient availability. Amino acid signals are transmitted to mTORC1 through the Rag GTPases, which are localized on the lysosomal surface by the Ragulator complex. The Rag GTPases receive amino acid signals from multiple upstream regulators. One negative regulator, GATOR1, is a GTPase activating protein (GAP) for RagA. GATOR1 binds to the Rag GTPases via two modes: an inhibitory mode and a GAP mode. How these two binding interactions coordinate to process amino acid signals is unknown. Here, we resolved three cryo-EM structural models of the GATOR1-Rag-Ragulator complex, with the Rag-Ragulator subcomplex occupying the inhibitory site, the GAP site, and both binding sites simultaneously. When the Rag GTPases bind to GATOR1 at the GAP site, both Rag subunits contact GATOR1 to coordinate their nucleotide loading states. These results reveal a potential GAP mechanism of GATOR1 during the mTORC1 inactivation process.
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Affiliation(s)
- Shawn B Egri
- Program in Molecular Medicine, University of Massachusetts Chan Medical School, 373 Plantation St, Worcester, MA 01605, USA
| | - Christna Ouch
- Department of Biochemistry & Molecular Pharmacology, University of Massachusetts Chan Medical School, 364 Plantation St, Worcester, MA 01605, USA
| | - Hui-Ting Chou
- Howard Hughes Medical Institute, Janelia Research Campus, 19700 Helix Drive, Ashburn, VA 20147, USA
| | - Zhiheng Yu
- Howard Hughes Medical Institute, Janelia Research Campus, 19700 Helix Drive, Ashburn, VA 20147, USA
| | - Kangkang Song
- Department of Biochemistry & Molecular Pharmacology, University of Massachusetts Chan Medical School, 364 Plantation St, Worcester, MA 01605, USA
| | - Chen Xu
- Department of Biochemistry & Molecular Pharmacology, University of Massachusetts Chan Medical School, 364 Plantation St, Worcester, MA 01605, USA
| | - Kuang Shen
- Program in Molecular Medicine, University of Massachusetts Chan Medical School, 373 Plantation St, Worcester, MA 01605, USA.
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20
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NPRL2 Inhibition of mTORC1 Controls Sodium Channel Expression and Brain Amino Acid Homeostasis. eNeuro 2022; 9:ENEURO.0317-21.2022. [PMID: 35165201 PMCID: PMC8896560 DOI: 10.1523/eneuro.0317-21.2022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 02/07/2022] [Accepted: 02/08/2022] [Indexed: 12/19/2022] Open
Abstract
Genetic mutations in nitrogen permease regulator-like 2 (NPRL2) are associated with a wide spectrum of familial focal epilepsies, autism, and sudden unexpected death of epileptics (SUDEP), but the mechanisms by which NPRL2 contributes to these effects are not well known. NPRL2 is a requisite subunit of the GAP activity toward Rags 1 (GATOR1) complex, which functions as a negative regulator of mammalian target of rapamycin complex 1 (mTORC1) kinase when intracellular amino acids are low. Here, we show that loss of NPRL2 expression in mouse excitatory glutamatergic neurons causes seizures before death, consistent with SUDEP in humans with epilepsy. Additionally, the absence of NPRL2 expression increases mTORC1-dependent signal transduction and significantly alters amino acid homeostasis in the brain. Loss of NPRL2 reduces dendritic branching and increases the strength of electrically stimulated action potentials (APs) in neurons. The increased AP strength is consistent with elevated expression of epilepsy-linked, voltage-gated sodium channels in the NPRL2-deficient brain. Targeted deletion of NPRL2 in primary neurons increases the expression of sodium channel Scn1A, whereas treatment with the pharmacological mTORC1 inhibitor called rapamycin prevents Scn1A upregulation. These studies demonstrate a novel role of NPRL2 and mTORC1 signaling in the regulation of sodium channels, which can contribute to seizures and early lethality.
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21
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Nowosad A, Besson A. Lysosomes at the Crossroads of Cell Metabolism, Cell Cycle, and Stemness. Int J Mol Sci 2022; 23:ijms23042290. [PMID: 35216401 PMCID: PMC8879101 DOI: 10.3390/ijms23042290] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Revised: 02/11/2022] [Accepted: 02/16/2022] [Indexed: 02/07/2023] Open
Abstract
Initially described as lytic bodies due to their degradative and recycling functions, lysosomes play a critical role in metabolic adaptation to nutrient availability. More recently, the contribution of lysosomal proteins to cell signaling has been established, and lysosomes have emerged as signaling hubs that regulate diverse cellular processes, including cell proliferation and cell fate. Deciphering these signaling pathways has revealed an extensive crosstalk between the lysosomal and cell cycle machineries that is only beginning to be understood. Recent studies also indicate that a number of lysosomal proteins are involved in the regulation of embryonic and adult stem cell fate and identity. In this review, we will focus on the role of the lysosome as a signaling platform with an emphasis on its function in integrating nutrient sensing with proliferation and cell cycle progression, as well as in stemness-related features, such as self-renewal and quiescence.
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Affiliation(s)
- Ada Nowosad
- Molecular, Cellular and Developmental Biology Department (MCD), Centre de Biologie Intégrative (CBI), University of Toulouse, CNRS, UPS, 31062 Toulouse, France;
- Department of Oncology, KULeuven, Laboratory for Molecular Cancer Biology, Center for Cancer Biology, VIB, 3000 Leuven, Belgium
| | - Arnaud Besson
- Molecular, Cellular and Developmental Biology Department (MCD), Centre de Biologie Intégrative (CBI), University of Toulouse, CNRS, UPS, 31062 Toulouse, France;
- Correspondence: ; Tel.: +33-561558486
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22
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Sun Y, Wan L, Yan H, Li Z, Yang G. Phenotypic and Genotypic Characterization of NPRL2-Related Epilepsy: Two Case Reports and Literature Review. Front Neurol 2021; 12:780799. [PMID: 34912289 PMCID: PMC8667312 DOI: 10.3389/fneur.2021.780799] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Accepted: 10/29/2021] [Indexed: 11/22/2022] Open
Abstract
The phenotype of nitrogen permease regulator-like 2 (NPRL2) gene-related epilepsy clinically manifests as a range of epilepsy syndromes, including familial focal epilepsy with variable foci (FFEVF), sleep-related hypermotor epilepsy (SHE), temporal lobe epilepsy (TLE), frontal lobe epilepsy (FLE), and infantile spasms (IS). The association between phenotype and genotype of NPRL2 variants has not been widely explored. This study aimed to explore the phenotype and genotype spectrum of NPRL2-related epilepsy. Here, we presented two clinical cases with NPRL2-related epilepsy, and discussed the characteristics, diagnosis, and treatment processes in the context of existing literature. Two novel NPRL2 likely pathogenic variants were identified by next-generation sequencing, including one splicing mutation (c.933-1G>A), and one frameshift mutation (c.257delG). The results of literature review showed that there were a total of 20 patients with NPRL2-related epilepsy whose mutations were mostly missense and hereditary. These findings indicate that the possibility of NPRL2 gene mutations in focal epilepsy should be considered for patients with family history, and that patients carrying different NPRL2 variants have different clinical manifestations. Our study expanded the genotype spectrum of NPRL2 and suggested that the type of NPRL2 variants might provide important information for the prognosis evaluation.
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Affiliation(s)
- Yulin Sun
- Department of Pediatrics, Chinese PLA General Hospital, Beijing, China.,Department of Pediatrics, The First Medical Center, Chinese PLA General Hospital, Beijing, China
| | - Lin Wan
- Department of Pediatrics, Chinese PLA General Hospital, Beijing, China.,Department of Pediatrics, The First Medical Center, Chinese PLA General Hospital, Beijing, China
| | - Huimin Yan
- Department of Pediatrics, Chinese PLA General Hospital, Beijing, China.,Department of Pediatrics, The First Medical Center, Chinese PLA General Hospital, Beijing, China
| | - Zhichao Li
- Department of Pediatrics, Chinese PLA General Hospital, Beijing, China.,Department of Pediatrics, The First Medical Center, Chinese PLA General Hospital, Beijing, China
| | - Guang Yang
- Department of Pediatrics, Chinese PLA General Hospital, Beijing, China.,Department of Pediatrics, The First Medical Center, Chinese PLA General Hospital, Beijing, China.,The Second School of Clinical Medicine, Southern Medical University, Guangzhou, China
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23
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Zhang S, Lin X, Hou Q, Hu Z, Wang Y, Wang Z. Regulation of mTORC1 by amino acids in mammalian cells: A general picture of recent advances. ACTA ACUST UNITED AC 2021; 7:1009-1023. [PMID: 34738031 PMCID: PMC8536509 DOI: 10.1016/j.aninu.2021.05.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Revised: 05/13/2021] [Accepted: 05/18/2021] [Indexed: 12/11/2022]
Abstract
The mechanistic target of rapamycin complex 1 (mTORC1) integrates various types of signal inputs, such as energy, growth factors, and amino acids to regulate cell growth and proliferation mainly through the 2 direct downstream targets, eukaryotic translation initiation factor 4E-binding protein 1 (4EBP1) and ribosomal protein S6 kinase 1 (S6K1). Most of the signal arms upstream of mTORC1 including energy status, stress signals, and growth factors converge on the tuberous sclerosis complex (TSC) - Ras homologue enriched in brain (Rheb) axis. Amino acids, however, are distinct from other signals and modulate mTORC1 using a unique pathway. In recent years, the transmission mechanism of amino acid signals upstream of mTORC1 has been gradually elucidated, and some sensors or signal transmission pathways for individual amino acids have also been discovered. With the help of these findings, we propose a general picture of recent advances, which demonstrates that various amino acids from lysosomes, cytoplasm, and Golgi are sensed by their respective sensors. These signals converge on mTORC1 and form a huge and complicated signal network with multiple synergies, antagonisms, and feedback mechanisms.
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Affiliation(s)
- Shizhe Zhang
- Key Laboratory of Ruminant Nutrition and Physiology, College of Animal Science and Technology, Shandong Agricultural University, No. 61, Daizong Street, Tai'an, Shandong, China
| | - Xueyan Lin
- Key Laboratory of Ruminant Nutrition and Physiology, College of Animal Science and Technology, Shandong Agricultural University, No. 61, Daizong Street, Tai'an, Shandong, China
| | - Qiuling Hou
- Key Laboratory of Ruminant Nutrition and Physiology, College of Animal Science and Technology, Shandong Agricultural University, No. 61, Daizong Street, Tai'an, Shandong, China
| | - Zhiyong Hu
- Key Laboratory of Ruminant Nutrition and Physiology, College of Animal Science and Technology, Shandong Agricultural University, No. 61, Daizong Street, Tai'an, Shandong, China
| | - Yun Wang
- Key Laboratory of Ruminant Nutrition and Physiology, College of Animal Science and Technology, Shandong Agricultural University, No. 61, Daizong Street, Tai'an, Shandong, China
| | - Zhonghua Wang
- Key Laboratory of Ruminant Nutrition and Physiology, College of Animal Science and Technology, Shandong Agricultural University, No. 61, Daizong Street, Tai'an, Shandong, China
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24
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Loissell-Baltazar YA, Dokudovskaya S. SEA and GATOR 10 Years Later. Cells 2021; 10:cells10102689. [PMID: 34685669 PMCID: PMC8534245 DOI: 10.3390/cells10102689] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 09/30/2021] [Accepted: 10/03/2021] [Indexed: 12/17/2022] Open
Abstract
The SEA complex was described for the first time in yeast Saccharomyces cerevisiae ten years ago, and its human homologue GATOR complex two years later. During the past decade, many advances on the SEA/GATOR biology in different organisms have been made that allowed its role as an essential upstream regulator of the mTORC1 pathway to be defined. In this review, we describe these advances in relation to the identification of multiple functions of the SEA/GATOR complex in nutrient response and beyond and highlight the consequence of GATOR mutations in cancer and neurodegenerative diseases.
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Su MY, Fromm SA, Remis J, Toso DB, Hurley JH. Structural basis for the ARF GAP activity and specificity of the C9orf72 complex. Nat Commun 2021; 12:3786. [PMID: 34145292 PMCID: PMC8213707 DOI: 10.1038/s41467-021-24081-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Accepted: 05/27/2021] [Indexed: 02/05/2023] Open
Abstract
Mutation of C9ORF72 is the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontal temporal degeneration (FTD), which is attributed to both a gain and loss of function. C9orf72 forms a complex with SMCR8 and WDR41, which was reported to have GTPase activating protein activity toward ARF proteins, RAB8A, and RAB11A. We determined the cryo-EM structure of ARF1-GDP-BeF3- bound to C9orf72:SMCR8:WDR41. The SMCR8longin and C9orf72longin domains form the binding pocket for ARF1. One face of the C9orf72longin domain holds ARF1 in place, while the SMCR8longin positions the catalytic finger Arg147 in the ARF1 active site. Mutations in interfacial residues of ARF1 and C9orf72 reduced or eliminated GAP activity. RAB8A GAP required ~10-fold higher concentrations of the C9orf72 complex than for ARF1. These data support a specific function for the C9orf72 complex as an ARF GAP. The structure also provides a model for the active forms of the longin domain GAPs of FLCN and NPRL2 that regulate the Rag GTPases of the mTORC1 pathway.
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Affiliation(s)
- Ming-Yuan Su
- School of Medicine, Southern University of Science and Technology, Shenzhen, China
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
- California Institute for Quantitative Biosciences, University of California, Berkeley, CA, USA
| | - Simon A Fromm
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
- California Institute for Quantitative Biosciences, University of California, Berkeley, CA, USA
- Imaging Centre, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Jonathan Remis
- California Institute for Quantitative Biosciences, University of California, Berkeley, CA, USA
| | - Daniel B Toso
- California Institute for Quantitative Biosciences, University of California, Berkeley, CA, USA
| | - James H Hurley
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA.
- California Institute for Quantitative Biosciences, University of California, Berkeley, CA, USA.
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26
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Seibert M, Kurrle N, Schnütgen F, Serve H. Amino acid sensory complex proteins in mTORC1 and macroautophagy regulation. Matrix Biol 2021; 100-101:65-83. [DOI: 10.1016/j.matbio.2021.01.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 01/02/2021] [Accepted: 01/02/2021] [Indexed: 12/15/2022]
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27
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Abstract
mTORC1 is a central player in cell growth, a process that is tightly regulated by the availability of nutrients and that controls various aspects of metabolism in the normal cell and in severe diseases such as cancers. mTORC1 is a large multiprotein complex, composed of the kinase subunit mTOR, of Ragulator, which attaches mTOR to the lysosome membrane, of the atypical Rag GTPases and the small GTPase RheB, whose nucleotide states directly dictate its localization to the lysosome and its kinase activity, and of RAPTOR, an adaptor that assembles the complex. The activity of the Rag GTPases is further controlled by the GATOR1 and folliculin complexes, which regulate their GTP/GDP conversion. Here, we review recent structures of important components of the mTORC1 machinery, determined by cryo-electron microscopy for the most part, which allow to reconstitute the architecture of active mTORC1 at near atomic resolution. Notably, we discuss how these structures shed new light on the roles of Rag GTPases and their regulators in mTORC1 regulation, and the perspectives that they open towards understanding the inner workings of mTORC1 on the lysosomal membrane.
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Affiliation(s)
- Agata Nawrotek
- CNRS, LBPA, UMR 8113,École normale supérieure Paris-Saclay, Université Paris-Saclay, 4 avenue des Sciences, 91190 Gif-sur-Yvette, France
| | - Jacqueline Cherfils
- CNRS, LBPA, UMR 8113,École normale supérieure Paris-Saclay, Université Paris-Saclay, 4 avenue des Sciences, 91190 Gif-sur-Yvette, France
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28
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Venugopal A, Bishu S. Nutrient sensing. Curr Opin Gastroenterol 2021; 37:114-120. [PMID: 33507029 DOI: 10.1097/mog.0000000000000709] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
PURPOSE OF REVIEW Sensing of nutrients is foundational for life and allows for cellular adaption to environmental stress. The aim of this review is to provide a basic background and overview of new data on cellular nutrient sensing. RECENT FINDINGS We focus on sensing of energy by adenosine monophosphate-activated protein kinase, sensing of amino acids via general amino acid control nonderepresible 2 and regulation of cellular metabolism via mammalian target of rapamycin pathways. Over the last 5 years, new data has elucidated how these pathways are both interconnected and regulated by amino acids. SUMMARY Regulation of these pathways is complex and tightly orchestrated in order to provide unified cellular responses that meet environmental demands. Amino acids provide key cues for the regulation of mammalian target of rapamycin pathways, in particular.
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Affiliation(s)
- Anand Venugopal
- Division of Gastroenterology, Department of Medicine, University of Michigan, Ann Arbor, USA
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29
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Prentzell MT, Rehbein U, Cadena Sandoval M, De Meulemeester AS, Baumeister R, Brohée L, Berdel B, Bockwoldt M, Carroll B, Chowdhury SR, von Deimling A, Demetriades C, Figlia G, de Araujo MEG, Heberle AM, Heiland I, Holzwarth B, Huber LA, Jaworski J, Kedra M, Kern K, Kopach A, Korolchuk VI, van 't Land-Kuper I, Macias M, Nellist M, Palm W, Pusch S, Ramos Pittol JM, Reil M, Reintjes A, Reuter F, Sampson JR, Scheldeman C, Siekierska A, Stefan E, Teleman AA, Thomas LE, Torres-Quesada O, Trump S, West HD, de Witte P, Woltering S, Yordanov TE, Zmorzynska J, Opitz CA, Thedieck K. G3BPs tether the TSC complex to lysosomes and suppress mTORC1 signaling. Cell 2021; 184:655-674.e27. [PMID: 33497611 PMCID: PMC7868890 DOI: 10.1016/j.cell.2020.12.024] [Citation(s) in RCA: 64] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 11/03/2020] [Accepted: 12/14/2020] [Indexed: 12/22/2022]
Abstract
Ras GTPase-activating protein-binding proteins 1 and 2 (G3BP1 and G3BP2, respectively) are widely recognized as core components of stress granules (SGs). We report that G3BPs reside at the cytoplasmic surface of lysosomes. They act in a non-redundant manner to anchor the tuberous sclerosis complex (TSC) protein complex to lysosomes and suppress activation of the metabolic master regulator mechanistic target of rapamycin complex 1 (mTORC1) by amino acids and insulin. Like the TSC complex, G3BP1 deficiency elicits phenotypes related to mTORC1 hyperactivity. In the context of tumors, low G3BP1 levels enhance mTORC1-driven breast cancer cell motility and correlate with adverse outcomes in patients. Furthermore, G3bp1 inhibition in zebrafish disturbs neuronal development and function, leading to white matter heterotopia and neuronal hyperactivity. Thus, G3BPs are not only core components of SGs but also a key element of lysosomal TSC-mTORC1 signaling.
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Affiliation(s)
- Mirja Tamara Prentzell
- Brain Cancer Metabolism Group, German Consortium of Translational Cancer Research (DKTK) & German Cancer Research Center (DKFZ), Heidelberg 69120, Germany; Department of Pediatrics, Section Systems Medicine of Metabolism and Signaling, University of Groningen, University Medical Center Groningen, Groningen 9700 RB, The Netherlands; Department of Bioinformatics and Molecular Genetics (Faculty of Biology), University of Freiburg, Freiburg 79104, Germany; Spemann Graduate School of Biology and Medicine (SGBM), University of Freiburg, Freiburg 79104, Germany
| | - Ulrike Rehbein
- Department of Pediatrics, Section Systems Medicine of Metabolism and Signaling, University of Groningen, University Medical Center Groningen, Groningen 9700 RB, The Netherlands; Department for Neuroscience, School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, Oldenburg 26129, Germany; Institute of Biochemistry and Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck 6020, Austria
| | - Marti Cadena Sandoval
- Department of Pediatrics, Section Systems Medicine of Metabolism and Signaling, University of Groningen, University Medical Center Groningen, Groningen 9700 RB, The Netherlands; Institute of Biochemistry and Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck 6020, Austria
| | - Ann-Sofie De Meulemeester
- Laboratory for Molecular Biodiscovery, Department of Pharmaceutical and Pharmacological Sciences, University of Leuven, Leuven BE-3000, Belgium
| | - Ralf Baumeister
- Department of Bioinformatics and Molecular Genetics (Faculty of Biology), University of Freiburg, Freiburg 79104, Germany; Spemann Graduate School of Biology and Medicine (SGBM), University of Freiburg, Freiburg 79104, Germany; Signalling Research Centres BIOSS and CIBSS & ZBMZ Center for Biochemistry and Molecular Cell Research (Faculty of Medicine), University of Freiburg, Freiburg 79104, Germany
| | - Laura Brohée
- Cell Growth Control in Health and Age-Related Disease Group, Max Planck Institute for Biology of Ageing (MPI-AGE), Cologne 50931, Germany
| | - Bianca Berdel
- Brain Cancer Metabolism Group, German Consortium of Translational Cancer Research (DKTK) & German Cancer Research Center (DKFZ), Heidelberg 69120, Germany
| | - Mathias Bockwoldt
- Department of Arctic and Marine Biology, UiT The Arctic University of Norway, Tromsø 9037, Norway
| | - Bernadette Carroll
- School of Biochemistry, Biomedical Sciences Building, University Walk, Bristol BS8 1TD, UK
| | - Suvagata Roy Chowdhury
- Cell Signaling and Metabolism Group, German Cancer Research Center (DKFZ), Heidelberg 69120, Germany
| | - Andreas von Deimling
- German Consortium of Translational Cancer Research (DKTK), Clinical Cooperation Unit Neuropathology, German Cancer Research Center (DKFZ), Heidelberg 69120, Germany; Department of Neuropathology, Institute of Pathology, Heidelberg University, Heidelberg 69120, Germany
| | - Constantinos Demetriades
- Cell Growth Control in Health and Age-Related Disease Group, Max Planck Institute for Biology of Ageing (MPI-AGE), Cologne 50931, Germany; CECAD Cluster of Excellence, University of Cologne, Cologne 50931, Germany
| | - Gianluca Figlia
- Signal Transduction in Cancer and Metabolism, German Cancer Research Center (DKFZ), Heidelberg 69120, Germany; Heidelberg University, Heidelberg 69120, Germany
| | | | - Alexander M Heberle
- Department of Pediatrics, Section Systems Medicine of Metabolism and Signaling, University of Groningen, University Medical Center Groningen, Groningen 9700 RB, The Netherlands; Institute of Biochemistry and Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck 6020, Austria
| | - Ines Heiland
- Department of Arctic and Marine Biology, UiT The Arctic University of Norway, Tromsø 9037, Norway
| | - Birgit Holzwarth
- Department of Bioinformatics and Molecular Genetics (Faculty of Biology), University of Freiburg, Freiburg 79104, Germany
| | - Lukas A Huber
- Institute of Cell Biology, Biocenter, Medical University of Innsbruck, Innsbruck 6020, Austria; Austrian Drug Screening Institute (ADSI), Innsbruck 6020, Austria
| | - Jacek Jaworski
- Laboratory of Molecular and Cellular Neurobiology, International Institute of Molecular and Cell Biology in Warsaw, Warsaw 02-109, Poland
| | - Magdalena Kedra
- Laboratory of Molecular and Cellular Neurobiology, International Institute of Molecular and Cell Biology in Warsaw, Warsaw 02-109, Poland
| | - Katharina Kern
- Brain Cancer Metabolism Group, German Consortium of Translational Cancer Research (DKTK) & German Cancer Research Center (DKFZ), Heidelberg 69120, Germany
| | - Andrii Kopach
- Laboratory of Molecular and Cellular Neurobiology, International Institute of Molecular and Cell Biology in Warsaw, Warsaw 02-109, Poland
| | - Viktor I Korolchuk
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Ineke van 't Land-Kuper
- Department of Pediatrics, Section Systems Medicine of Metabolism and Signaling, University of Groningen, University Medical Center Groningen, Groningen 9700 RB, The Netherlands; Department for Neuroscience, School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, Oldenburg 26129, Germany
| | - Matylda Macias
- Laboratory of Molecular and Cellular Neurobiology, International Institute of Molecular and Cell Biology in Warsaw, Warsaw 02-109, Poland
| | - Mark Nellist
- Department of Clinical Genetics, Erasmus Medical Center, Rotterdam 3015 GD, The Netherlands
| | - Wilhelm Palm
- Cell Signaling and Metabolism Group, German Cancer Research Center (DKFZ), Heidelberg 69120, Germany
| | - Stefan Pusch
- German Consortium of Translational Cancer Research (DKTK), Clinical Cooperation Unit Neuropathology, German Cancer Research Center (DKFZ), Heidelberg 69120, Germany; Department of Neuropathology, Institute of Pathology, Heidelberg University, Heidelberg 69120, Germany
| | - Jose Miguel Ramos Pittol
- Institute of Biochemistry and Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck 6020, Austria
| | - Michèle Reil
- Brain Cancer Metabolism Group, German Consortium of Translational Cancer Research (DKTK) & German Cancer Research Center (DKFZ), Heidelberg 69120, Germany
| | - Anja Reintjes
- Institute of Biochemistry and Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck 6020, Austria
| | - Friederike Reuter
- Brain Cancer Metabolism Group, German Consortium of Translational Cancer Research (DKTK) & German Cancer Research Center (DKFZ), Heidelberg 69120, Germany
| | - Julian R Sampson
- Institute of Medical Genetics, Division of Cancer and Genetics, Cardiff University Medical School, Cardiff CF14 4AY, UK
| | - Chloë Scheldeman
- Laboratory for Molecular Biodiscovery, Department of Pharmaceutical and Pharmacological Sciences, University of Leuven, Leuven BE-3000, Belgium; Neurogenetics Research Group, VUB, Brussels 1090, Belgium
| | - Aleksandra Siekierska
- Laboratory for Molecular Biodiscovery, Department of Pharmaceutical and Pharmacological Sciences, University of Leuven, Leuven BE-3000, Belgium
| | - Eduard Stefan
- Institute of Biochemistry and Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck 6020, Austria
| | - Aurelio A Teleman
- Signal Transduction in Cancer and Metabolism, German Cancer Research Center (DKFZ), Heidelberg 69120, Germany; Heidelberg University, Heidelberg 69120, Germany
| | - Laura E Thomas
- Institute of Life Science, Swansea University, Swansea SA2 8PP, UK
| | - Omar Torres-Quesada
- Institute of Biochemistry and Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck 6020, Austria
| | - Saskia Trump
- Molecular Epidemiology Unit, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health (BIH), Berlin 13353, Germany
| | - Hannah D West
- Institute of Medical Genetics, Division of Cancer and Genetics, Cardiff University Medical School, Cardiff CF14 4AY, UK
| | - Peter de Witte
- Laboratory for Molecular Biodiscovery, Department of Pharmaceutical and Pharmacological Sciences, University of Leuven, Leuven BE-3000, Belgium
| | - Sandra Woltering
- Brain Cancer Metabolism Group, German Consortium of Translational Cancer Research (DKTK) & German Cancer Research Center (DKFZ), Heidelberg 69120, Germany
| | - Teodor E Yordanov
- Institute of Cell Biology, Biocenter, Medical University of Innsbruck, Innsbruck 6020, Austria; Division of Cell and Developmental Biology, Institute for Molecular Bioscience, University of Queensland, St Lucia QLD 4072, Australia
| | - Justyna Zmorzynska
- Laboratory of Molecular and Cellular Neurobiology, International Institute of Molecular and Cell Biology in Warsaw, Warsaw 02-109, Poland
| | - Christiane A Opitz
- Brain Cancer Metabolism Group, German Consortium of Translational Cancer Research (DKTK) & German Cancer Research Center (DKFZ), Heidelberg 69120, Germany; Department of Neurology, University Hospital Heidelberg and National Center for Tumor Diseases, Heidelberg 69120, Germany.
| | - Kathrin Thedieck
- Department of Pediatrics, Section Systems Medicine of Metabolism and Signaling, University of Groningen, University Medical Center Groningen, Groningen 9700 RB, The Netherlands; Department for Neuroscience, School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, Oldenburg 26129, Germany; Institute of Biochemistry and Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck 6020, Austria.
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30
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Fukuda T, Sofyantoro F, Tai YT, Chia KH, Matsuda T, Murase T, Morozumi Y, Tatebe H, Kanki T, Shiozaki K. Tripartite suppression of fission yeast TORC1 signaling by the GATOR1-Sea3 complex, the TSC complex, and Gcn2 kinase. eLife 2021; 10:60969. [PMID: 33534698 PMCID: PMC7857730 DOI: 10.7554/elife.60969] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Accepted: 01/22/2021] [Indexed: 01/07/2023] Open
Abstract
Mammalian target of rapamycin complex 1 (TORC1) is controlled by the GATOR complex composed of the GATOR1 subcomplex and its inhibitor, the GATOR2 subcomplex, sensitive to amino acid starvation. Previously, we identified fission yeast GATOR1 that prevents deregulated activation of TORC1 (Chia et al., 2017). Here, we report identification and characterization of GATOR2 in fission yeast. Unexpectedly, the GATOR2 subunit Sea3, an ortholog of mammalian WDR59, is physically and functionally proximal to GATOR1, rather than GATOR2, attenuating TORC1 activity. The fission yeast GATOR complex is dispensable for TORC1 regulation in response to amino acid starvation, which instead activates the Gcn2 pathway to inhibit TORC1 and induce autophagy. On the other hand, nitrogen starvation suppresses TORC1 through the combined actions of the GATOR1-Sea3 complex, the Gcn2 pathway, and the TSC complex, another conserved TORC1 inhibitor. Thus, multiple, parallel signaling pathways implement negative regulation of TORC1 to ensure proper cellular starvation responses.
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Affiliation(s)
- Tomoyuki Fukuda
- Department of Cellular Physiology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Fajar Sofyantoro
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara, Japan.,Faculty of Biology, Universitas Gadjah Mada, Yogyakarta, Indonesia
| | - Yen Teng Tai
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara, Japan
| | - Kim Hou Chia
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara, Japan
| | - Takato Matsuda
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara, Japan
| | - Takaaki Murase
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara, Japan
| | - Yuichi Morozumi
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara, Japan
| | - Hisashi Tatebe
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara, Japan
| | - Tomotake Kanki
- Department of Cellular Physiology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Kazuhiro Shiozaki
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara, Japan.,Department of Microbiology and Molecular Genetics, University of California, Davis, Davis, United States
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31
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Sciarretta S, Forte M, Frati G, Sadoshima J. The complex network of mTOR signaling in the heart. Cardiovasc Res 2021; 118:424-439. [PMID: 33512477 DOI: 10.1093/cvr/cvab033] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 12/13/2020] [Accepted: 01/26/2021] [Indexed: 12/13/2022] Open
Abstract
The mechanistic target of rapamycin (mTOR) integrates several intracellular and extracellular signals involved in the regulation of anabolic and catabolic processes. mTOR assembles into two macromolecular complexes, named mTORC1 and mTORC2, which have different regulators, substrates and functions. Studies of gain- and loss-of-function animal models of mTOR signaling revealed that mTORC1/2 elicit both adaptive and maladaptive functions in the cardiovascular system. Both mTORC1 and mTORC2 are indispensable for driving cardiac development and cardiac adaption to stress, such as pressure overload. However, persistent and deregulated mTORC1 activation in the heart is detrimental during stress and contributes to the development and progression of cardiac remodeling and genetic and metabolic cardiomyopathies. In this review, we discuss the latest findings regarding the role of mTOR in the cardiovascular system, both under basal conditions and during stress, such as pressure overload, ischemia and metabolic stress. Current data suggest that mTOR modulation may represent a potential therapeutic strategy for the treatment of cardiac diseases.
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Affiliation(s)
- Sebastiano Sciarretta
- Department of Medical and Surgical Sciences and Biotechnologies, Sapienza University of Rome, Latina, Italy.,IRCCS Neuromed, Pozzilli (IS), Italy
| | | | - Giacomo Frati
- Department of Medical and Surgical Sciences and Biotechnologies, Sapienza University of Rome, Latina, Italy.,IRCCS Neuromed, Pozzilli (IS), Italy
| | - Junichi Sadoshima
- Department of Cell Biology and Molecular Medicine, Cardiovascular Research Institute, Rutgers New Jersey Medical School, Newark, NJ, USA
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32
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Condon KJ, Orozco JM, Adelmann CH, Spinelli JB, van der Helm PW, Roberts JM, Kunchok T, Sabatini DM. Genome-wide CRISPR screens reveal multitiered mechanisms through which mTORC1 senses mitochondrial dysfunction. Proc Natl Acad Sci U S A 2021; 118:e2022120118. [PMID: 33483422 PMCID: PMC7848693 DOI: 10.1073/pnas.2022120118] [Citation(s) in RCA: 64] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
In mammalian cells, nutrients and growth factors signal through an array of upstream proteins to regulate the mTORC1 growth control pathway. Because the full complement of these proteins has not been systematically identified, we developed a FACS-based CRISPR-Cas9 genetic screening strategy to pinpoint genes that regulate mTORC1 activity. Along with almost all known positive components of the mTORC1 pathway, we identified many genes that impact mTORC1 activity, including DCAF7, CSNK2B, SRSF2, IRS4, CCDC43, and HSD17B10 Using the genome-wide screening data, we generated a focused sublibrary containing single guide RNAs (sgRNAs) targeting hundreds of genes and carried out epistasis screens in cells lacking nutrient- and stress-responsive mTORC1 modulators, including GATOR1, AMPK, GCN2, and ATF4. From these data, we pinpointed mitochondrial function as a particularly important input into mTORC1 signaling. While it is well appreciated that mitochondria signal to mTORC1, the mechanisms are not completely clear. We find that the kinases AMPK and HRI signal, with varying kinetics, mitochondrial distress to mTORC1, and that HRI acts through the ATF4-dependent up-regulation of both Sestrin2 and Redd1. Loss of both AMPK and HRI is sufficient to render mTORC1 signaling largely resistant to mitochondrial dysfunction induced by the ATP synthase inhibitor oligomycin as well as the electron transport chain inhibitors piericidin and antimycin. Taken together, our data reveal a catalog of genes that impact the mTORC1 pathway and clarify the multifaceted ways in which mTORC1 senses mitochondrial dysfunction.
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Affiliation(s)
- Kendall J Condon
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142
- Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02139
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02142
- Broad Institute of Harvard and Massachusetts Institute of Technology, Cambridge, MA 02142
| | - Jose M Orozco
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142
- Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02139
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02142
- Broad Institute of Harvard and Massachusetts Institute of Technology, Cambridge, MA 02142
| | - Charles H Adelmann
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142
- Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02139
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02142
- Broad Institute of Harvard and Massachusetts Institute of Technology, Cambridge, MA 02142
| | - Jessica B Spinelli
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142
- Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02139
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02142
- Broad Institute of Harvard and Massachusetts Institute of Technology, Cambridge, MA 02142
| | - Pim W van der Helm
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142
- Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02139
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02142
- Broad Institute of Harvard and Massachusetts Institute of Technology, Cambridge, MA 02142
| | - Justin M Roberts
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142
- Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02139
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02142
- Broad Institute of Harvard and Massachusetts Institute of Technology, Cambridge, MA 02142
| | - Tenzin Kunchok
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142
| | - David M Sabatini
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142;
- Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02139
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02142
- Broad Institute of Harvard and Massachusetts Institute of Technology, Cambridge, MA 02142
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33
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Morozumi Y, Shiozaki K. Conserved and Divergent Mechanisms That Control TORC1 in Yeasts and Mammals. Genes (Basel) 2021; 12:genes12010088. [PMID: 33445779 PMCID: PMC7828246 DOI: 10.3390/genes12010088] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Revised: 01/10/2021] [Accepted: 01/11/2021] [Indexed: 12/23/2022] Open
Abstract
Target of rapamycin complex 1 (TORC1), a serine/threonine-protein kinase complex highly conserved among eukaryotes, coordinates cellular growth and metabolism with environmental cues, including nutrients and growth factors. Aberrant TORC1 signaling is associated with cancers and various human diseases, and TORC1 also plays a key role in ageing and lifespan, urging current active research on the mechanisms of TORC1 regulation in a variety of model organisms. Identification and characterization of the RAG small GTPases as well as their regulators, many of which are highly conserved from yeast to humans, led to a series of breakthroughs in understanding the molecular bases of TORC1 regulation. Recruitment of mammalian TORC1 (mTORC1) by RAGs to lysosomal membranes is a key step for mTORC1 activation. Interestingly, the RAG GTPases in fission yeast are primarily responsible for attenuation of TORC1 activity on vacuoles, the yeast equivalent of lysosomes. In this review, we summarize our current knowledge about the functions of TORC1 regulators on yeast vacuoles, and illustrate the conserved and divergent mechanisms of TORC1 regulation between yeasts and mammals.
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Affiliation(s)
- Yuichi Morozumi
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan;
- Correspondence: ; Tel.: +81-743-72-5543
| | - Kazuhiro Shiozaki
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan;
- Department of Microbiology and Molecular Genetics, University of California, Davis, CA 95616, USA
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Yang S, Zhang Y, Ting CY, Bettedi L, Kim K, Ghaniam E, Lilly MA. The Rag GTPase Regulates the Dynamic Behavior of TSC Downstream of Both Amino Acid and Growth Factor Restriction. Dev Cell 2020; 55:272-288.e5. [PMID: 32898476 PMCID: PMC7657977 DOI: 10.1016/j.devcel.2020.08.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 06/30/2020] [Accepted: 08/10/2020] [Indexed: 01/09/2023]
Abstract
The dysregulation of the metabolic regulator TOR complex I (TORC1) contributes to a wide array of human pathologies. Tuberous sclerosis complex (TSC) is a potent inhibitor of TORC1. Here, we demonstrate that the Rag GTPase acts in both the amino-acid-sensing and growth factor signaling pathways to control TORC1 activity through the regulation of TSC dynamics in HeLa cells and Drosophila. We find that TSC lysosomal-cytosolic exchange increases in response to both amino acid and growth factor restriction. Moreover, the rate of exchange mirrors TSC function, with depletions of the Rag GTPase blocking TSC lysosomal mobility and rescuing TORC1 activity. Finally, we show that the GATOR2 complex controls the phosphorylation of TSC2, which is essential for TSC exchange. Our data support the model that the amino acid and growth factor signaling pathways converge on the Rag GTPase to inhibit TORC1 activity through the regulation of TSC dynamics.
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Affiliation(s)
- Shu Yang
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Yingbiao Zhang
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Chun-Yuan Ting
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Lucia Bettedi
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Kuikwon Kim
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Elena Ghaniam
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Mary A Lilly
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA.
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Zhu Y, Zhou J, Niu P, Chen H, Shi D. Cardamonin inhibits cell proliferation by caspase-mediated cleavage of Raptor. Naunyn Schmiedebergs Arch Pharmacol 2020; 394:809-817. [PMID: 33043385 DOI: 10.1007/s00210-020-01986-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 10/04/2020] [Indexed: 12/16/2022]
Abstract
The antiproliferative effect of cardamonin on mTORC1 is related with downregulation of Raptor. We investigated the mechanism that cardamonin decreases Raptor expression through caspase-mediated protein degradation. SKOV3 cells and HeLa cells were pretreated with caspase inhibitor z-VAD-fmk for 30 min and then exposed to different doses of cardamonin and cisplatin, respectively. We analyzed the gene expression of caspases based on TCGA and GTEx gene expression data in serous cystadenocarcinoma and normal tissues, monitored caspase activity by caspase colorimetric assay kit, detected expression of mTORC1-associated proteins and apoptosis-associated proteins by western blotting, and finally detected cell viability by methyl thiazolyl tetrazolium (MTT) assay. A different expression of caspases except caspase-1 was found between serous cystadenocarcinoma and normal tissues. Raptor was cleaved when caspases were activated by cisplatin and caspase-6/caspase-8 was activated by cardamonin in SKOV3 cells. We further used a monoclonal antibody recognizing the N-terminal part of Raptor to find that Raptor was cleaved into a smaller fragment of about 70 kDa by cardamonin and was rescued by z-VAD-fmk treatment. As a result of Raptor cleavage, mTORC1 activity was decreased and cell viability was inhibited, while cell apoptosis was induced in SKOV3 cells. Notably, similar results are only observed in HeLa cells with a high dose of cardamonin. We concluded that caspase-mediated cleavage of Raptor might be an important mechanism in that cardamonin regulated Raptor and mTORC1 activity.
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Affiliation(s)
- Yanting Zhu
- Department of Pharmacy, Fujian Maternity and Child Health Hospital, Affiliated Hospital of Fujian Medical University, 18 Daoshan Road, Fuzhou, 350001, Fujian, China
| | - Jintuo Zhou
- Department of Pharmacy, Fujian Maternity and Child Health Hospital, Affiliated Hospital of Fujian Medical University, 18 Daoshan Road, Fuzhou, 350001, Fujian, China
| | - Peiguang Niu
- Department of Pharmacy, Fujian Maternity and Child Health Hospital, Affiliated Hospital of Fujian Medical University, 18 Daoshan Road, Fuzhou, 350001, Fujian, China
| | - Huajiao Chen
- Department of Pharmacy, Fujian Maternity and Child Health Hospital, Affiliated Hospital of Fujian Medical University, 18 Daoshan Road, Fuzhou, 350001, Fujian, China
| | - Daohua Shi
- Department of Pharmacy, Fujian Maternity and Child Health Hospital, Affiliated Hospital of Fujian Medical University, 18 Daoshan Road, Fuzhou, 350001, Fujian, China.
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Klofas LK, Short BP, Snow JP, Sinnaeve J, Rushing GV, Westlake G, Weinstein W, Ihrie RA, Ess KC, Carson RP. DEPDC5 haploinsufficiency drives increased mTORC1 signaling and abnormal morphology in human iPSC-derived cortical neurons. Neurobiol Dis 2020; 143:104975. [PMID: 32574724 PMCID: PMC7462127 DOI: 10.1016/j.nbd.2020.104975] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Revised: 05/21/2020] [Accepted: 06/13/2020] [Indexed: 01/21/2023] Open
Abstract
Mutations in the DEPDC5 gene can cause epilepsy, including forms with and without brain malformations. The goal of this study was to investigate the contribution of DEPDC5 gene dosage to the underlying neuropathology of DEPDC5-related epilepsies. We generated induced pluripotent stem cells (iPSCs) from epilepsy patients harboring heterozygous loss of function mutations in DEPDC5. Patient iPSCs displayed increases in both phosphorylation of ribosomal protein S6 and proliferation rate, consistent with elevated mTORC1 activation. In line with these findings, we observed increased soma size in patient iPSC-derived cortical neurons that was rescued with rapamycin treatment. These data indicate that human cells heterozygous for DEPDC5 loss-of-function mutations are haploinsufficient for control of mTORC1 signaling. Our findings suggest that human pathology differs from mouse models of DEPDC5-related epilepsies, which do not show consistent phenotypic differences in heterozygous neurons, and support the need for human-based models to affirm and augment the findings from animal models of DEPDC5-related epilepsy.
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Affiliation(s)
- Lindsay K Klofas
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN, USA
| | - Brittany P Short
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN, USA
| | - John P Snow
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Justine Sinnaeve
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | | | - Grant Westlake
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Will Weinstein
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Rebecca A Ihrie
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN, USA; Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN, USA; Department of Neurological Surgery, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Kevin C Ess
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN, USA; Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN, USA; Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Robert P Carson
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN, USA; Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN, USA; Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN, USA.
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37
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Su MY, Fromm SA, Zoncu R, Hurley JH. Structure of the C9orf72 ARF GAP complex that is haploinsufficient in ALS and FTD. Nature 2020; 585:251-255. [PMID: 32848248 PMCID: PMC8054479 DOI: 10.1038/s41586-020-2633-x] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Accepted: 05/20/2020] [Indexed: 12/17/2022]
Abstract
Mutation of C9orf72 is the most prevalent defect associated with amyotrophic lateral sclerosis and frontotemporal degeneration1. Together with hexanucleotide-repeat expansion2,3, haploinsufficiency of C9orf72 contributes to neuronal dysfunction4-6. Here we determine the structure of the C9orf72-SMCR8-WDR41 complex by cryo-electron microscopy. C9orf72 and SMCR8 both contain longin and DENN (differentially expressed in normal and neoplastic cells) domains7, and WDR41 is a β-propeller protein that binds to SMCR8 such that the whole structure resembles an eye slip hook. Contacts between WDR41 and the DENN domain of SMCR8 drive the lysosomal localization of the complex in conditions of amino acid starvation. The structure suggested that C9orf72-SMCR8 is a GTPase-activating protein (GAP), and we found that C9orf72-SMCR8-WDR41 acts as a GAP for the ARF family of small GTPases. These data shed light on the function of C9orf72 in normal physiology, and in amyotrophic lateral sclerosis and frontotemporal degeneration.
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Affiliation(s)
- Ming-Yuan Su
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA.,California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA, USA
| | - Simon A Fromm
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA.,California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA, USA
| | - Roberto Zoncu
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA.,California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA, USA
| | - James H Hurley
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA. .,California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA, USA. .,Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
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38
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Tafur L, Kefauver J, Loewith R. Structural Insights into TOR Signaling. Genes (Basel) 2020; 11:E885. [PMID: 32759652 PMCID: PMC7464330 DOI: 10.3390/genes11080885] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 07/31/2020] [Accepted: 08/02/2020] [Indexed: 12/31/2022] Open
Abstract
The Target of Rapamycin (TOR) is a highly conserved serine/threonine protein kinase that performs essential roles in the control of cellular growth and metabolism. TOR acts in two distinct multiprotein complexes, TORC1 and TORC2 (mTORC1 and mTORC2 in humans), which maintain different aspects of cellular homeostasis and orchestrate the cellular responses to diverse environmental challenges. Interest in understanding TOR signaling is further motivated by observations that link aberrant TOR signaling to a variety of diseases, ranging from epilepsy to cancer. In the last few years, driven in large part by recent advances in cryo-electron microscopy, there has been an explosion of available structures of (m)TORC1 and its regulators, as well as several (m)TORC2 structures, derived from both yeast and mammals. In this review, we highlight and summarize the main findings from these reports and discuss both the fascinating and unexpected molecular biology revealed and how this knowledge will potentially contribute to new therapeutic strategies to manipulate signaling through these clinically relevant pathways.
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Affiliation(s)
- Lucas Tafur
- Department of Molecular Biology, University of Geneva, 30 quai Ernest-Ansermet, CH1211 Geneva, Switzerland; (L.T.); (J.K.)
| | - Jennifer Kefauver
- Department of Molecular Biology, University of Geneva, 30 quai Ernest-Ansermet, CH1211 Geneva, Switzerland; (L.T.); (J.K.)
| | - Robbie Loewith
- Department of Molecular Biology, University of Geneva, 30 quai Ernest-Ansermet, CH1211 Geneva, Switzerland; (L.T.); (J.K.)
- Swiss National Centre for Competence in Research (NCCR) in Chemical Biology, University of Geneva, Sciences II, Room 3-308, 30 Quai Ernest-Ansermet, CH1211 Geneva, Switzerland
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39
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Liu GY, Sabatini DM. mTOR at the nexus of nutrition, growth, ageing and disease. Nat Rev Mol Cell Biol 2020; 21:183-203. [PMID: 31937935 PMCID: PMC7102936 DOI: 10.1038/s41580-019-0199-y] [Citation(s) in RCA: 1335] [Impact Index Per Article: 333.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/26/2019] [Indexed: 12/21/2022]
Abstract
The mTOR pathway integrates a diverse set of environmental cues, such as growth factor signals and nutritional status, to direct eukaryotic cell growth. Over the past two and a half decades, mapping of the mTOR signalling landscape has revealed that mTOR controls biomass accumulation and metabolism by modulating key cellular processes, including protein synthesis and autophagy. Given the pathway's central role in maintaining cellular and physiological homeostasis, dysregulation of mTOR signalling has been implicated in metabolic disorders, neurodegeneration, cancer and ageing. In this Review, we highlight recent advances in our understanding of the complex regulation of the mTOR pathway and discuss its function in the context of physiology, human disease and pharmacological intervention.
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Affiliation(s)
- Grace Y Liu
- Whitehead Institute for Biomedical Research, Cambridge, MA, USA
- Department of Biology, Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA, USA
- Broad Institute, Cambridge, MA, USA
- The David H. Koch Institute for Integrative Cancer Research at MIT, Cambridge, MA, USA
| | - David M Sabatini
- Whitehead Institute for Biomedical Research, Cambridge, MA, USA.
- Department of Biology, Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA, USA.
- Broad Institute, Cambridge, MA, USA.
- The David H. Koch Institute for Integrative Cancer Research at MIT, Cambridge, MA, USA.
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40
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González A, Hall MN, Lin SC, Hardie DG. AMPK and TOR: The Yin and Yang of Cellular Nutrient Sensing and Growth Control. Cell Metab 2020; 31:472-492. [PMID: 32130880 DOI: 10.1016/j.cmet.2020.01.015] [Citation(s) in RCA: 394] [Impact Index Per Article: 98.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The AMPK (AMP-activated protein kinase) and TOR (target-of-rapamycin) pathways are interlinked, opposing signaling pathways involved in sensing availability of nutrients and energy and regulation of cell growth. AMPK (Yin, or the "dark side") is switched on by lack of energy or nutrients and inhibits cell growth, while TOR (Yang, or the "bright side") is switched on by nutrient availability and promotes cell growth. Genes encoding the AMPK and TOR complexes are found in almost all eukaryotes, suggesting that these pathways arose very early during eukaryotic evolution. During the development of multicellularity, an additional tier of cell-extrinsic growth control arose that is mediated by growth factors, but these often act by modulating nutrient uptake so that AMPK and TOR remain the underlying regulators of cellular growth control. In this review, we discuss the evolution, structure, and regulation of the AMPK and TOR pathways and the complex mechanisms by which they interact.
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Affiliation(s)
- Asier González
- Biozentrum, University of Basel, CH4056 Basel, Switzerland
| | - Michael N Hall
- Biozentrum, University of Basel, CH4056 Basel, Switzerland
| | - Sheng-Cai Lin
- School of Life Sciences, Xiamen University, Xiamen, 361102 Fujian, China
| | - D Grahame Hardie
- Division of Cell Signalling & Immunology, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, Scotland, UK.
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41
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Shen K, Rogala KB, Chou HT, Huang RK, Yu Z, Sabatini DM. Cryo-EM Structure of the Human FLCN-FNIP2-Rag-Ragulator Complex. Cell 2019; 179:1319-1329.e8. [PMID: 31704029 PMCID: PMC7008705 DOI: 10.1016/j.cell.2019.10.036] [Citation(s) in RCA: 80] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2019] [Revised: 10/08/2019] [Accepted: 10/28/2019] [Indexed: 12/22/2022]
Abstract
mTORC1 controls anabolic and catabolic processes in response to nutrients through the Rag GTPase heterodimer, which is regulated by multiple upstream protein complexes. One such regulator, FLCN-FNIP2, is a GTPase activating protein (GAP) for RagC/D, but despite its important role, how it activates the Rag GTPase heterodimer remains unknown. We used cryo-EM to determine the structure of FLCN-FNIP2 in a complex with the Rag GTPases and Ragulator. FLCN-FNIP2 adopts an extended conformation with two pairs of heterodimerized domains. The Longin domains heterodimerize and contact both nucleotide binding domains of the Rag heterodimer, while the DENN domains interact at the distal end of the structure. Biochemical analyses reveal a conserved arginine on FLCN as the catalytic arginine finger and lead us to interpret our structure as an on-pathway intermediate. These data reveal features of a GAP-GTPase interaction and the structure of a critical component of the nutrient-sensing mTORC1 pathway.
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Affiliation(s)
- Kuang Shen
- Whitehead Institute for Biomedical Research and Department of Biology, Massachusetts Institute of Technology, 455 Main Street, Cambridge, MA 02142, USA; Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Koch Institute for Integrative Cancer Research, 77 Massachusetts Avenue, Cambridge, MA 02139, USA; Broad Institute of Harvard and Massachusetts Institute of Technology, 7 Cambridge Center, Cambridge, MA 02142, USA; Program in Molecular Medicine, University of Massachusetts Medical School, 373 Plantation Street, Worcester, 01605, USA
| | - Kacper B Rogala
- Whitehead Institute for Biomedical Research and Department of Biology, Massachusetts Institute of Technology, 455 Main Street, Cambridge, MA 02142, USA; Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Koch Institute for Integrative Cancer Research, 77 Massachusetts Avenue, Cambridge, MA 02139, USA; Broad Institute of Harvard and Massachusetts Institute of Technology, 7 Cambridge Center, Cambridge, MA 02142, USA
| | - Hui-Ting Chou
- Howard Hughes Medical Institute, Janelia Research Campus, 19700 Helix Drive, Ashburn, VA 20147, USA
| | - Rick K Huang
- Howard Hughes Medical Institute, Janelia Research Campus, 19700 Helix Drive, Ashburn, VA 20147, USA
| | - Zhiheng Yu
- Howard Hughes Medical Institute, Janelia Research Campus, 19700 Helix Drive, Ashburn, VA 20147, USA.
| | - David M Sabatini
- Whitehead Institute for Biomedical Research and Department of Biology, Massachusetts Institute of Technology, 455 Main Street, Cambridge, MA 02142, USA; Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Koch Institute for Integrative Cancer Research, 77 Massachusetts Avenue, Cambridge, MA 02139, USA; Broad Institute of Harvard and Massachusetts Institute of Technology, 7 Cambridge Center, Cambridge, MA 02142, USA.
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Abstract
The mechanistic target of rapamycin (mTOR) signaling pathway coordinates environmental and intracellular cues to control eukaryotic cell growth. As a pivot point between anabolic and catabolic processes, mTOR complex 1 (mTORC1) signaling has established roles in regulating metabolism, translation and autophagy. Hyperactivity of the mTOR pathway is associated with numerous human diseases, including diabetes, cancer and epilepsy. Pharmacological inhibition of the mTOR pathway can extend lifespan in a variety of model organisms. Given its broad control of essential cellular processes and clear relevance to human health, there is extensive interest in elucidating how upstream inputs regulate mTORC1 activation. In this Cell Science at a Glance article and accompanying poster, we summarize our understanding of how extracellular and intracellular signals feed into the mTOR pathway, how the lysosome acts as an mTOR signaling hub, and how downstream signaling controls autophagy and lysosome biogenesis.
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Affiliation(s)
- Kendall J Condon
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA.,Department of Biology, Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.,Broad Institute, Cambridge, MA 02142, USA.,The David H. Koch Institute for Integrative Cancer Research at MIT, Cambridge, MA 02139, USA
| | - David M Sabatini
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA .,Department of Biology, Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.,Broad Institute, Cambridge, MA 02142, USA.,The David H. Koch Institute for Integrative Cancer Research at MIT, Cambridge, MA 02139, USA
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43
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Pharmacology of metformin - An update. Eur J Pharmacol 2019; 865:172782. [PMID: 31705902 DOI: 10.1016/j.ejphar.2019.172782] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Revised: 10/24/2019] [Accepted: 11/04/2019] [Indexed: 02/06/2023]
Abstract
Despite being a successful diabetes type 2 drug for more than a half-century in Europe, the mode of action of metformin is still debated. It is the purpose of this review to inform the reader about most recent findings for metformin with respect to its antidiabetic activity as well as proposed benefits beyond glucose control in humans. Clinical evidence now suggests that most of metformin benefits originate from its actions in the gut, involving hormone signaling by glucagon-like peptide 1 and peptide YY. Growth differentiation factor 15, also mainly produced in the gut, was first identified as a biomarker for metformin use but is now suggested to play a significant role in e.g. weight loss of prediabetics. The pharmacokinetics of the drug in humans as basis for pharmacodynamics, resulting in high tissue levels of the intestinal wall, including the colon, proven by biopsies, is presented. A critical survey of metformin actions on mitochondria, increasing the AMP/ATP ratio but also acting as a mild uncoupler, and of postulated new cellular targets (lysosomes) is included.
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Lawrence RE, Fromm SA, Fu Y, Yokom AL, Kim DJ, Thelen AM, Young LN, Lim CY, Samelson AJ, Hurley JH, Zoncu R. Structural mechanism of a Rag GTPase activation checkpoint by the lysosomal folliculin complex. Science 2019; 366:971-977. [PMID: 31672913 DOI: 10.1126/science.aax0364] [Citation(s) in RCA: 95] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Accepted: 10/23/2019] [Indexed: 12/16/2022]
Abstract
The tumor suppressor folliculin (FLCN) enables nutrient-dependent activation of the mechanistic target of rapamycin complex 1 (mTORC1) protein kinase via its guanosine triphosphatase (GTPase) activating protein (GAP) activity toward the GTPase RagC. Concomitant with mTORC1 inactivation by starvation, FLCN relocalizes from the cytosol to lysosomes. To determine the lysosomal function of FLCN, we reconstituted the human lysosomal FLCN complex (LFC) containing FLCN, its partner FLCN-interacting protein 2 (FNIP2), and the RagAGDP:RagCGTP GTPases as they exist in the starved state with their lysosomal anchor Ragulator complex and determined its cryo-electron microscopy structure to 3.6 angstroms. The RagC-GAP activity of FLCN was inhibited within the LFC, owing to displacement of a catalytically required arginine in FLCN from the RagC nucleotide. Disassembly of the LFC and release of the RagC-GAP activity of FLCN enabled mTORC1-dependent regulation of the master regulator of lysosomal biogenesis, transcription factor E3, implicating the LFC as a checkpoint in mTORC1 signaling.
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Affiliation(s)
- Rosalie E Lawrence
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720, USA.,The Paul F. Glenn Center for Aging Research at the University of California, Berkeley, Berkeley, CA 94720, USA
| | - Simon A Fromm
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720, USA
| | - Yangxue Fu
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720, USA
| | - Adam L Yokom
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720, USA
| | - Do Jin Kim
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720, USA
| | - Ashley M Thelen
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720, USA.,The Paul F. Glenn Center for Aging Research at the University of California, Berkeley, Berkeley, CA 94720, USA
| | - Lindsey N Young
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720, USA
| | - Chun-Yan Lim
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720, USA.,The Paul F. Glenn Center for Aging Research at the University of California, Berkeley, Berkeley, CA 94720, USA
| | - Avi J Samelson
- The Paul F. Glenn Center for Aging Research at the University of California, Berkeley, Berkeley, CA 94720, USA.,Institute for Neurodegenerative Diseases, University of California at San Francisco, San Francisco, CA 94158, USA
| | - James H Hurley
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720, USA. .,California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA 94720, USA.,Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Roberto Zoncu
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720, USA. .,The Paul F. Glenn Center for Aging Research at the University of California, Berkeley, Berkeley, CA 94720, USA.,California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA 94720, USA
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45
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Dawson RE, Nieto Guil AF, Robertson LJ, Piltz SG, Hughes JN, Thomas PQ. Functional screening of GATOR1 complex variants reveals a role for mTORC1 deregulation in FCD and focal epilepsy. Neurobiol Dis 2019; 134:104640. [PMID: 31639411 DOI: 10.1016/j.nbd.2019.104640] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2019] [Revised: 10/07/2019] [Accepted: 10/13/2019] [Indexed: 12/20/2022] Open
Abstract
Mutations in the GAP activity toward RAGs 1 (GATOR1) complex genes (DEPDC5, NPRL2 and NPRL3) have been associated with focal epilepsy and focal cortical dysplasia (FCD). GATOR1 functions as an inhibitor of the mTORC1 signalling pathway, indicating that the downstream effects of mTORC1 deregulation underpin the disease. However, the vast majority of putative disease-causing variants have not been functionally assessed for mTORC1 repression activity. Here, we develop a novel in vitro functional assay that enables rapid assessment of GATOR1-gene variants. Surprisingly, of the 17 variants tested, we show that only six showed significantly impaired mTORC1 inhibition. To further investigate variant function in vivo, we generated a conditional Depdc5 mouse which modelled a 'second-hit' mechanism of disease. Generation of Depdc5 null 'clones' in the embryonic brain resulted in mTORC1 hyperactivity and modelled epilepsy and FCD symptoms including large dysmorphic neurons, defective migration and lower seizure thresholds. Using this model, we validated DEPDC5 variant F164del to be loss-of-function. We also show that Q542P is not functionally compromised in vivo, consistent with our in vitro findings. Overall, our data show that mTORC1 deregulation is the central pathological mechanism for GATOR1 variants and also indicates that a significant proportion of putative disease variants are pathologically inert, highlighting the importance of GATOR1 variant functional assessment.
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Affiliation(s)
- Ruby E Dawson
- School of Biological Sciences, University of Adelaide, Adelaide, SA 5005, Australia; Robinson Research Institute, University of Adelaide, Adelaide, SA 5005, Australia.
| | - Alvaro F Nieto Guil
- School of Medicine, University of Adelaide, Adelaide, SA 5005, Australia; Robinson Research Institute, University of Adelaide, Adelaide, SA 5005, Australia.
| | - Louise J Robertson
- School of Medicine, University of Adelaide, Adelaide, SA 5005, Australia; Robinson Research Institute, University of Adelaide, Adelaide, SA 5005, Australia.
| | - Sandra G Piltz
- School of Medicine, University of Adelaide, Adelaide, SA 5005, Australia; Robinson Research Institute, University of Adelaide, Adelaide, SA 5005, Australia.
| | - James N Hughes
- School of Biological Sciences, University of Adelaide, Adelaide, SA 5005, Australia; Robinson Research Institute, University of Adelaide, Adelaide, SA 5005, Australia.
| | - Paul Q Thomas
- School of Medicine, University of Adelaide, Adelaide, SA 5005, Australia; Robinson Research Institute, University of Adelaide, Adelaide, SA 5005, Australia; Precision Medicine Theme, South Australia Health and Medical Research Institute, Adelaide, SA 5000, Australia.
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Phosphorylation of DEPDC5, a component of the GATOR1 complex, releases inhibition of mTORC1 and promotes tumor growth. Proc Natl Acad Sci U S A 2019; 116:20505-20510. [PMID: 31548394 DOI: 10.1073/pnas.1904774116] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The Pim and AKT serine/threonine protein kinases are implicated as drivers of cancer. Their regulation of tumor growth is closely tied to the ability of these enzymes to mainly stimulate protein synthesis by activating mTORC1 (mammalian target of rapamycin complex 1) signaling, although the exact mechanism is not completely understood. mTORC1 activity is normally suppressed by amino acid starvation through a cascade of multiple regulatory protein complexes, e.g., GATOR1, GATOR2, and KICSTOR, that reduce the activity of Rag GTPases. Bioinformatic analysis revealed that DEPDC5 (DEP domain containing protein 5), a component of GATOR1 complex, contains Pim and AKT protein kinase phosphorylation consensus sequences. DEPDC5 phosphorylation by Pim and AKT kinases was confirmed in cancer cells through the use of phospho-specific antibodies and transfection of phospho-inactive DEPDC5 mutants. Consistent with these findings, during amino acid starvation the elevated expression of Pim1 overcame the amino acid inhibitory protein cascade and activated mTORC1. In contrast, the knockout of DEPDC5 partially blocked the ability of small molecule inhibitors against Pim and AKT kinases both singly and in combination to suppress tumor growth and mTORC1 activity in vitro and in vivo. In animal experiments knocking in a glutamic acid (S1530E) in DEPDC5, a phospho mimic, in tumor cells induced a significant level of resistance to Pim and the combination of Pim and AKT inhibitors. Our results indicate a phosphorylation-dependent regulatory mechanism targeting DEPDC5 through which Pim1 and AKT act as upstream effectors of mTORC1 to facilitate proliferation and survival of cancer cells.
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