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Mammalian ECD Protein Is a Novel Negative Regulator of the PERK Arm of the Unfolded Protein Response. Mol Cell Biol 2017; 37:MCB.00030-17. [PMID: 28652267 PMCID: PMC5574048 DOI: 10.1128/mcb.00030-17] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2017] [Accepted: 06/17/2017] [Indexed: 01/01/2023] Open
Abstract
Mammalian Ecdysoneless (ECD) is a highly conserved ortholog of the DrosophilaEcd gene product whose mutations impair the synthesis of Ecdysone and produce cell-autonomous survival defects, but the mechanisms by which ECD functions are largely unknown. Here we present evidence that ECD regulates the endoplasmic reticulum (ER) stress response. ER stress induction led to a reduced ECD protein level, but this effect was not seen in PKR-like ER kinase knockout (PERK-KO) or phosphodeficient eukaryotic translation initiation factor 2α (eIF2α) mouse embryonic fibroblasts (MEFs); moreover, ECD mRNA levels were increased, suggesting impaired ECD translation as the mechanism for reduced protein levels. ECD colocalizes and coimmunoprecipitates with PERK and GRP78. ECD depletion increased the levels of both phospho-PERK (p-PERK) and p-eIF2α, and these effects were enhanced upon ER stress induction. Reciprocally, overexpression of ECD led to marked decreases in p-PERK, p-eIF2α, and ATF4 levels but robust increases in GRP78 protein levels. However, GRP78 mRNA levels were unchanged, suggesting a posttranscriptional event. Knockdown of GRP78 reversed the attenuating effect of ECD overexpression on PERK signaling. Significantly, overexpression of ECD provided a survival advantage to cells upon ER stress induction. Taken together, our data demonstrate that ECD promotes survival upon ER stress by increasing GRP78 protein levels to enhance the adaptive folding protein in the ER to attenuate PERK signaling.
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102
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Mao YQ, Houry WA. The Role of Pontin and Reptin in Cellular Physiology and Cancer Etiology. Front Mol Biosci 2017; 4:58. [PMID: 28884116 PMCID: PMC5573869 DOI: 10.3389/fmolb.2017.00058] [Citation(s) in RCA: 82] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Accepted: 08/03/2017] [Indexed: 12/29/2022] Open
Abstract
Pontin (RUVBL1, TIP49, TIP49a, Rvb1) and Reptin (RUVBL2, TIP48, TIP49b, Rvb2) are highly conserved ATPases of the AAA+ (ATPases Associated with various cellular Activities) superfamily and are involved in various cellular processes that are important for oncogenesis. First identified as being upregulated in hepatocellular carcinoma and colorectal cancer, their overexpression has since been shown in multiple cancer types such as breast, lung, gastric, esophageal, pancreatic, kidney, bladder as well as lymphatic, and leukemic cancers. However, their exact functions are still quite unknown as they interact with many molecular complexes with vastly different downstream effectors. Within the nucleus, Pontin and Reptin participate in the TIP60 and INO80 complexes important for chromatin remodeling. Although not transcription factors themselves, Pontin and Reptin modulate the transcriptional activities of bona fide proto-oncogenes such as MYC and β-catenin. They associate with proteins involved in DNA damage repair such as PIKK complexes as well as with the core complex of Fanconi anemia pathway. They have also been shown to be important for cell cycle progression, being involved in assembly of telomerase, mitotic spindle, RNA polymerase II, and snoRNPs. When the two ATPases localize to the cytoplasm, they were reported to promote cancer cell invasion and metastasis. Due to their various roles in carcinogenesis, it is not surprising that Pontin and Reptin are proving to be important biomarkers for diagnosis and prognosis of various cancers. They are also current targets for the development of new therapeutic anticancer drugs.
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Affiliation(s)
- Yu-Qian Mao
- Department of Biochemistry, University of TorontoToronto, ON, Canada
| | - Walid A Houry
- Department of Biochemistry, University of TorontoToronto, ON, Canada.,Department of Chemistry, University of TorontoToronto, ON, Canada
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103
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Rivera-Calzada A, Pal M, Muñoz-Hernández H, Luque-Ortega JR, Gil-Carton D, Degliesposti G, Skehel JM, Prodromou C, Pearl LH, Llorca O. The Structure of the R2TP Complex Defines a Platform for Recruiting Diverse Client Proteins to the HSP90 Molecular Chaperone System. Structure 2017. [PMID: 28648606 PMCID: PMC5501727 DOI: 10.1016/j.str.2017.05.016] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The R2TP complex, comprising the Rvb1p-Rvb2p AAA-ATPases, Tah1p, and Pih1p in yeast, is a specialized Hsp90 co-chaperone required for the assembly and maturation of multi-subunit complexes. These include the small nucleolar ribonucleoproteins, RNA polymerase II, and complexes containing phosphatidylinositol-3-kinase-like kinases. The structure and stoichiometry of yeast R2TP and how it couples to Hsp90 are currently unknown. Here, we determine the 3D organization of yeast R2TP using sedimentation velocity analysis and cryo-electron microscopy. The 359-kDa complex comprises one Rvb1p/Rvb2p hetero-hexamer with domains II (DIIs) forming an open basket that accommodates a single copy of Tah1p-Pih1p. Tah1p-Pih1p binding to multiple DII domains regulates Rvb1p/Rvb2p ATPase activity. Using domain dissection and cross-linking mass spectrometry, we identified a unique region of Pih1p that is essential for interaction with Rvb1p/Rvb2p. These data provide a structural basis for understanding how R2TP couples an Hsp90 dimer to a diverse set of client proteins and complexes. Rvb1p-Rvb2p forms a hetero-hexamer with DII domains recruiting a single Tah1p-Pih1p Residues 230–250 in Pih1p are essential to bind Rvb1p-Rvb2p 3D structure of yeast R2TP couples an Hsp90 dimer to client proteins Tah1p-Pih1p binding to flexible DII domains stimulates Rvb1p-Rvb2p ATPase activity
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Affiliation(s)
- Angel Rivera-Calzada
- Centro de Investigaciones Biológicas (CIB), Spanish National Research Council (CSIC), Ramiro de Maeztu 9, 28040 Madrid, Spain
| | - Mohinder Pal
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9RQ, UK
| | - Hugo Muñoz-Hernández
- Centro de Investigaciones Biológicas (CIB), Spanish National Research Council (CSIC), Ramiro de Maeztu 9, 28040 Madrid, Spain
| | - Juan R Luque-Ortega
- Centro de Investigaciones Biológicas (CIB), Spanish National Research Council (CSIC), Ramiro de Maeztu 9, 28040 Madrid, Spain
| | - David Gil-Carton
- Structural Biology Unit, CIC bioGUNE, Bizkaia Technology Park, 48160 Derio, Spain
| | | | - J Mark Skehel
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Chrisostomos Prodromou
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9RQ, UK.
| | - Laurence H Pearl
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9RQ, UK.
| | - Oscar Llorca
- Centro de Investigaciones Biológicas (CIB), Spanish National Research Council (CSIC), Ramiro de Maeztu 9, 28040 Madrid, Spain; Structural Biology Programme, Spanish National Cancer Research Centre (CNIO), Melchor Fernández Almagro 3, 28029 Madrid, Spain.
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104
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Affiliation(s)
- Lifeng Yang
- Laboratory for Systems Biology of Human Diseases, Rice University, Houston, Texas 77005
- Department of Chemical and Biomolecular Engineering, Rice University, Houston, Texas 77005
| | - Sriram Venneti
- Department of Pathology, University of Michigan, Ann Arbor, Michigan 48109
| | - Deepak Nagrath
- Laboratory for Systems Biology of Human Diseases, Rice University, Houston, Texas 77005
- Department of Chemical and Biomolecular Engineering, Rice University, Houston, Texas 77005
- Department of Bioengineering, Rice University, Houston, Texas 77005
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan 48109
- Biointerfaces Institute, University of Michigan, Ann Arbor, Michigan 48109
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105
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Abstract
Beyond protein synthesis and autophagy, emerging evidence has implicated mTORC1 in regulating protein folding and proteasomal degradation as well, highlighting its prominent role in cellular proteome homeostasis or proteostasis. In addition to growth signals, mTORC1 senses and responds to a wide array of stresses, including energetic/metabolic stress, genotoxic stress, oxidative stress, osmotic stress, ER stress, proteotoxic stress, and psychological stress. Whereas growth signals unanimously stimulate mTORC1, stresses exert complex impacts on mTORC1, most of which are repressive. mTORC1 suppression, as a generic adaptive strategy, empowers cell survival under various stressful conditions. In this essay, we provide an overview of the emerging role of mTORC1 in proteostasis, the distinct molecular mechanisms through which mTORC1 reacts to diverse stresses, and the schemes exploited by cancer cells to circumvent stress-induced mTORC1 suppression. Hence, acting as a stress sensor, mTORC1 intimately couples stresses to cellular proteostasis.
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Affiliation(s)
- Kuo-Hui Su
- Mouse Cancer Genetics Program, Center for Cancer Research, NCI, Frederick, MD 21702, USA
| | - Chengkai Dai
- Mouse Cancer Genetics Program, Center for Cancer Research, NCI, Frederick, MD 21702, USA,Corresponding author: Chengkai Dai,
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106
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Abstract
Beyond protein synthesis and autophagy, emerging evidence has implicated mTORC1 in regulating protein folding and proteasomal degradation as well, highlighting its prominent role in cellular proteome homeostasis or proteostasis. In addition to growth signals, mTORC1 senses and responds to a wide array of stresses, including energetic/metabolic stress, genotoxic stress, oxidative stress, osmotic stress, ER stress, proteotoxic stress, and psychological stress. Whereas growth signals unanimously stimulate mTORC1, stresses exert complex impacts on mTORC1, most of which are repressive. mTORC1 suppression, as a generic adaptive strategy, empowers cell survival under various stressful conditions. In this essay, we provide an overview of the emerging role of mTORC1 in proteostasis, the distinct molecular mechanisms through which mTORC1 reacts to diverse stresses, and the schemes exploited by cancer cells to circumvent stress-induced mTORC1 suppression. Hence, acting as a stress sensor, mTORC1 intimately couples stresses to cellular proteostasis.
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Affiliation(s)
- Kuo-Hui Su
- Mouse Cancer Genetics Program, Center for Cancer Research, NCI, Frederick, MD 21702, USA
| | - Chengkai Dai
- Mouse Cancer Genetics Program, Center for Cancer Research, NCI, Frederick, MD 21702, USA
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107
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Lee SY, Kang MG, Shin S, Kwak C, Kwon T, Seo JK, Kim JS, Rhee HW. Architecture Mapping of the Inner Mitochondrial Membrane Proteome by Chemical Tools in Live Cells. J Am Chem Soc 2017; 139:3651-3662. [DOI: 10.1021/jacs.6b10418] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
| | | | - Sanghee Shin
- Center
for RNA Research, Institute of Basic Science (IBS), Seoul 08826, Korea
- School
of Biological Sciences, Seoul National University, Seoul 08826, Korea
| | | | | | | | - Jong-Seo Kim
- Center
for RNA Research, Institute of Basic Science (IBS), Seoul 08826, Korea
- School
of Biological Sciences, Seoul National University, Seoul 08826, Korea
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108
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Howell JJ, Hellberg K, Turner M, Talbott G, Kolar MJ, Ross DS, Hoxhaj G, Saghatelian A, Shaw RJ, Manning BD. Metformin Inhibits Hepatic mTORC1 Signaling via Dose-Dependent Mechanisms Involving AMPK and the TSC Complex. Cell Metab 2017; 25:463-471. [PMID: 28089566 PMCID: PMC5299044 DOI: 10.1016/j.cmet.2016.12.009] [Citation(s) in RCA: 267] [Impact Index Per Article: 38.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 11/02/2016] [Accepted: 12/10/2016] [Indexed: 02/08/2023]
Abstract
Metformin is the most widely prescribed drug for the treatment of type 2 diabetes. However, knowledge of the full effects of metformin on biochemical pathways and processes in its primary target tissue, the liver, is limited. One established effect of metformin is to decrease cellular energy levels. The AMP-activated protein kinase (AMPK) and mechanistic target of rapamycin (mTOR) complex 1 (mTORC1) are key regulators of metabolism that are respectively activated and inhibited in acute response to cellular energy depletion. Here we show that metformin robustly inhibits mTORC1 in mouse liver tissue and primary hepatocytes. Using mouse genetics, we find that at the lowest concentrations of metformin that inhibit hepatic mTORC1 signaling, this inhibition is dependent on AMPK and the tuberous sclerosis complex (TSC) protein complex (TSC complex). Finally, we show that metformin profoundly inhibits hepatocyte protein synthesis in a manner that is largely dependent on its ability to suppress mTORC1 signaling.
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Affiliation(s)
- Jessica J Howell
- Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA
| | - Kristina Hellberg
- Molecular and Cell Biology Laboratory, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Marc Turner
- Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA
| | - George Talbott
- Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA
| | - Matthew J Kolar
- Clayton Foundation Laboratories for Peptide Biology, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Debbie S Ross
- Molecular and Cell Biology Laboratory, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Gerta Hoxhaj
- Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA
| | - Alan Saghatelian
- Clayton Foundation Laboratories for Peptide Biology, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Reuben J Shaw
- Molecular and Cell Biology Laboratory, Salk Institute for Biological Studies, La Jolla, CA 92037, USA.
| | - Brendan D Manning
- Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA.
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109
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Switon K, Kotulska K, Janusz-Kaminska A, Zmorzynska J, Jaworski J. Molecular neurobiology of mTOR. Neuroscience 2017; 341:112-153. [PMID: 27889578 DOI: 10.1016/j.neuroscience.2016.11.017] [Citation(s) in RCA: 271] [Impact Index Per Article: 38.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Revised: 11/09/2016] [Accepted: 11/13/2016] [Indexed: 01/17/2023]
Abstract
Mammalian/mechanistic target of rapamycin (mTOR) is a serine-threonine kinase that controls several important aspects of mammalian cell function. mTOR activity is modulated by various intra- and extracellular factors; in turn, mTOR changes rates of translation, transcription, protein degradation, cell signaling, metabolism, and cytoskeleton dynamics. mTOR has been repeatedly shown to participate in neuronal development and the proper functioning of mature neurons. Changes in mTOR activity are often observed in nervous system diseases, including genetic diseases (e.g., tuberous sclerosis complex, Pten-related syndromes, neurofibromatosis, and Fragile X syndrome), epilepsy, brain tumors, and neurodegenerative disorders (Alzheimer's disease, Parkinson's disease, and Huntington's disease). Neuroscientists only recently began deciphering the molecular processes that are downstream of mTOR that participate in proper function of the nervous system. As a result, we are gaining knowledge about the ways in which aberrant changes in mTOR activity lead to various nervous system diseases. In this review, we provide a comprehensive view of mTOR in the nervous system, with a special focus on the neuronal functions of mTOR (e.g., control of translation, transcription, and autophagy) that likely underlie the contribution of mTOR to nervous system diseases.
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Affiliation(s)
- Katarzyna Switon
- International Institute of Molecular and Cell Biology, 4 Ks. Trojdena Street, Warsaw 02-109, Poland
| | - Katarzyna Kotulska
- Department of Neurology and Epileptology, Children's Memorial Health Institute, Aleja Dzieci Polskich 20, Warsaw 04-730, Poland
| | | | - Justyna Zmorzynska
- International Institute of Molecular and Cell Biology, 4 Ks. Trojdena Street, Warsaw 02-109, Poland
| | - Jacek Jaworski
- International Institute of Molecular and Cell Biology, 4 Ks. Trojdena Street, Warsaw 02-109, Poland.
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110
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Cai YD, Zhang Q, Zhang YH, Chen L, Huang T. Identification of Genes Associated with Breast Cancer Metastasis to Bone on a Protein–Protein Interaction Network with a Shortest Path Algorithm. J Proteome Res 2017; 16:1027-1038. [DOI: 10.1021/acs.jproteome.6b00950] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Yu-Dong Cai
- School
of Life Sciences, Shanghai University, Shanghai 200444 People’s Republic of China
| | - Qing Zhang
- School
of Life Sciences, Shanghai University, Shanghai 200444 People’s Republic of China
| | - Yu-Hang Zhang
- Institute
of Health Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, People’s Republic of China
| | - Lei Chen
- College
of Information Engineering, Shanghai Maritime University, Shanghai 201306, People’s Republic of China
| | - Tao Huang
- Institute
of Health Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, People’s Republic of China
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111
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Abstract
The resurgence of research into cancer metabolism has recently broadened interests beyond glucose and the Warburg effect to other nutrients, including glutamine. Because oncogenic alterations of metabolism render cancer cells addicted to nutrients, pathways involved in glycolysis or glutaminolysis could be exploited for therapeutic purposes. In this Review, we provide an updated overview of glutamine metabolism and its involvement in tumorigenesis in vitro and in vivo, and explore the recent potential applications of basic science discoveries in the clinical setting.
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Affiliation(s)
- Brian J. Altman
- Abramson Family Cancer Research Institute, Perelman School of
Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Abramson Cancer Center, Perelman School of Medicine, University of
Pennsylvania, Philadelphia, PA, 19104, USA
- Division of Hematology-Oncology, Department of Medicine, Perelman
School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Zachary E. Stine
- Abramson Family Cancer Research Institute, Perelman School of
Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Abramson Cancer Center, Perelman School of Medicine, University of
Pennsylvania, Philadelphia, PA, 19104, USA
- Division of Hematology-Oncology, Department of Medicine, Perelman
School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Chi V. Dang
- Abramson Family Cancer Research Institute, Perelman School of
Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Abramson Cancer Center, Perelman School of Medicine, University of
Pennsylvania, Philadelphia, PA, 19104, USA
- Division of Hematology-Oncology, Department of Medicine, Perelman
School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
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112
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Semba RD, Trehan I, Gonzalez-Freire M, Kraemer K, Moaddel R, Ordiz MI, Ferrucci L, Manary MJ. Perspective: The Potential Role of Essential Amino Acids and the Mechanistic Target of Rapamycin Complex 1 (mTORC1) Pathway in the Pathogenesis of Child Stunting. Adv Nutr 2016; 7:853-65. [PMID: 27633102 PMCID: PMC5015042 DOI: 10.3945/an.116.013276] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Stunting is the best summary measure of chronic malnutrition in children. Approximately one-quarter of children under age 5 worldwide are stunted. Lipid-based or micronutrient supplementation has little to no impact in reducing stunting, which suggests that other critical dietary nutrients are missing. A dietary pattern of poor-quality protein is associated with stunting. Stunted children have significantly lower circulating essential amino acids than do nonstunted children. Inadequate dietary intakes of essential amino acids could adversely affect growth, because amino acids are required for synthesis of proteins. The master growth regulation pathway, the mechanistic target of rapamycin complex 1 (mTORC1) pathway, is exquisitely sensitive to amino acid availability. mTORC1 integrates cues such as nutrients, growth factors, oxygen, and energy to regulate growth of bone, skeletal muscle, nervous system, gastrointestinal tract, hematopoietic cells, immune effector cells, organ size, and whole-body energy balance. mTORC1 represses protein and lipid synthesis and cell and organismal growth when amino acids are deficient. Over the past 4 decades, the main paradigm for child nutrition in developing countries has been micronutrient malnutrition, with relatively less attention paid to protein. In this Perspective, we present the view that essential amino acids and the mTORC1 pathway play a key role in child growth. The current assumption that total dietary protein intake is adequate for growth among most children in developing countries needs re-evaluation.
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Affiliation(s)
- Richard D Semba
- Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD;
| | - Indi Trehan
- Department of Pediatrics, Washington University in St. Louis, St. Louis, MO
| | | | - Klaus Kraemer
- Sight and Life, Basel, Switzerland; and Johns Hopkins Bloomberg School of Public Health, Baltimore, MD
| | | | - M Isabel Ordiz
- Department of Pediatrics, Washington University in St. Louis, St. Louis, MO
| | | | - Mark J Manary
- Department of Pediatrics, Washington University in St. Louis, St. Louis, MO
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113
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Roles of mTOR complexes in the kidney: implications for renal disease and transplantation. Nat Rev Nephrol 2016; 12:587-609. [PMID: 27477490 DOI: 10.1038/nrneph.2016.108] [Citation(s) in RCA: 143] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The mTOR pathway has a central role in the regulation of cell metabolism, growth and proliferation. Studies involving selective gene targeting of mTOR complexes (mTORC1 and mTORC2) in renal cell populations and/or pharmacologic mTOR inhibition have revealed important roles of mTOR in podocyte homeostasis and tubular transport. Important advances have also been made in understanding the role of mTOR in renal injury, polycystic kidney disease and glomerular diseases, including diabetic nephropathy. Novel insights into the roles of mTORC1 and mTORC2 in the regulation of immune cell homeostasis and function are helping to improve understanding of the complex effects of mTOR targeting on immune responses, including those that impact both de novo renal disease and renal allograft outcomes. Extensive experience in clinical renal transplantation has resulted in successful conversion of patients from calcineurin inhibitors to mTOR inhibitors at various times post-transplantation, with excellent long-term graft function. Widespread use of this practice has, however, been limited owing to mTOR-inhibitor- related toxicities. Unique attributes of mTOR inhibitors include reduced rates of squamous cell carcinoma and cytomegalovirus infection compared to other regimens. As understanding of the mechanisms by which mTORC1 and mTORC2 drive the pathogenesis of renal disease progresses, clinical studies of mTOR pathway targeting will enable testing of evolving hypotheses.
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114
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Abstract
The remarkable metabolic differences between cancer cells and normal cells result in the potential for targeted cancer therapy. The upregulation of glutaminolysis provides energetic advantages to cancer cells. The recently described link between glutaminolysis and autophagy, mediated by MTORC1, may constitute an attractive target for therapeutic strategies. A combination of therapies targeting simultane-ously cell signaling, cancer metabolism, and autophagy can solve therapy resistance and tumor relapse problems, commonly observed in patients treated with most of the current targeted therapies. In this review we summarize the mechanistic link between glutaminolysis and autophagy, and discuss the impacts of these processes on cancer progression and the potential for therapeutic intervention.
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115
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The Mechanistic Target of Rapamycin: The Grand ConducTOR of Metabolism and Aging. Cell Metab 2016; 23:990-1003. [PMID: 27304501 PMCID: PMC4910876 DOI: 10.1016/j.cmet.2016.05.009] [Citation(s) in RCA: 367] [Impact Index Per Article: 45.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Revised: 05/17/2016] [Accepted: 05/24/2016] [Indexed: 12/21/2022]
Abstract
Since the discovery that rapamycin, a small molecule inhibitor of the protein kinase mTOR (mechanistic target of rapamycin), can extend the lifespan of model organisms including mice, interest in understanding the physiological role and molecular targets of this pathway has surged. While mTOR was already well known as a regulator of growth and protein translation, it is now clear that mTOR functions as a central coordinator of organismal metabolism in response to both environmental and hormonal signals. This review discusses recent developments in our understanding of how mTOR signaling is regulated by nutrients and the role of the mTOR signaling pathway in key metabolic tissues. Finally, we discuss the molecular basis for the negative metabolic side effects associated with rapamycin treatment, which may serve as barriers to the adoption of rapamycin or similar compounds for the treatment of diseases of aging and metabolism.
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116
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Abstract
The activity of the mTORC1 protein complex depends on multiple metabolic inputs that regulate dimerization, recruitment to the lysosome, and activation. In this issue of Developmental Cell, David-Morrison et al. (2016) show that the Drosophila protein Wacky and its mammalian counterpart WAC act as adaptors in the process of mTORC1 dimerization.
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Affiliation(s)
- Jacques Montagne
- Institut for Integrative Biology of the Cell (I2BC), CNRS, Université Paris-Sud, CEA, UMR 9198, 91190 Gif-sur-Yvette, France.
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117
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David-Morrison G, Xu Z, Rui YN, Charng WL, Jaiswal M, Yamamoto S, Xiong B, Zhang K, Sandoval H, Duraine L, Zuo Z, Zhang S, Bellen HJ. WAC Regulates mTOR Activity by Acting as an Adaptor for the TTT and Pontin/Reptin Complexes. Dev Cell 2016; 36:139-51. [PMID: 26812014 DOI: 10.1016/j.devcel.2015.12.019] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Revised: 10/16/2015] [Accepted: 12/18/2015] [Indexed: 01/09/2023]
Abstract
The ability to sense energy status is crucial in the regulation of metabolism via the mechanistic Target of Rapamycin Complex 1 (mTORC1). The assembly of the TTT-Pontin/Reptin complex is responsive to changes in energy status. Under energy-sufficient conditions, the TTT-Pontin/Reptin complex promotes mTORC1 dimerization and mTORC1-Rag interaction, which are critical for mTORC1 activation. We show that WAC is a regulator of energy-mediated mTORC1 activity. In a Drosophila screen designed to isolate mutations that cause neuronal dysfunction, we identified wacky, the homolog of WAC. Loss of Wacky leads to neurodegeneration, defective mTOR activity, and increased autophagy. Wacky and WAC have conserved physical interactions with mTOR and its regulators, including Pontin and Reptin, which bind to the TTT complex to regulate energy-dependent activation of mTORC1. WAC promotes the interaction between TTT and Pontin/Reptin in an energy-dependent manner, thereby promoting mTORC1 activity by facilitating mTORC1 dimerization and mTORC1-Rag interaction.
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Affiliation(s)
| | - Zhen Xu
- The Brown Foundation Institute of Molecular Medicine, The University of Texas Medical School at Houston, Houston, TX 77030, USA
| | - Yan-Ning Rui
- The Brown Foundation Institute of Molecular Medicine, The University of Texas Medical School at Houston, Houston, TX 77030, USA
| | - Wu-Lin Charng
- Program in Developmental Biology, Baylor College of Medicine, Houston, TX 77030, USA; Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Manish Jaiswal
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Howard Hughes Medical Institute, Baylor College of Medicine, Houston, TX 77030, USA
| | - Shinya Yamamoto
- Program in Developmental Biology, Baylor College of Medicine, Houston, TX 77030, USA; Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX 77030, USA
| | - Bo Xiong
- Program in Developmental Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Ke Zhang
- Program in Structural and Computational Biology and Molecular Biophysics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Hector Sandoval
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Lita Duraine
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Howard Hughes Medical Institute, Baylor College of Medicine, Houston, TX 77030, USA
| | - Zhongyuan Zuo
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Sheng Zhang
- The Brown Foundation Institute of Molecular Medicine, The University of Texas Medical School at Houston, Houston, TX 77030, USA; Department of Neurobiology and Anatomy, The University of Texas Medical School at Houston, Houston, TX 77030, USA; Programs in Human and Molecular Genetics and Neuroscience, The Graduate School of Biomedical Sciences, The University of Texas Health Science Center at Houston (UTHealth), Houston, TX 77030, USA.
| | - Hugo J Bellen
- Program in Developmental Biology, Baylor College of Medicine, Houston, TX 77030, USA; Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Howard Hughes Medical Institute, Baylor College of Medicine, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX 77030, USA; Program in Structural and Computational Biology and Molecular Biophysics, Baylor College of Medicine, Houston, TX 77030, USA.
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118
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Tsokanos FF, Albert MA, Demetriades C, Spirohn K, Boutros M, Teleman AA. eIF4A inactivates TORC1 in response to amino acid starvation. EMBO J 2016; 35:1058-76. [PMID: 26988032 PMCID: PMC4868951 DOI: 10.15252/embj.201593118] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Accepted: 02/19/2016] [Indexed: 12/20/2022] Open
Abstract
Amino acids regulate TOR complex 1 (TORC1) via two counteracting mechanisms, one activating and one inactivating. The presence of amino acids causes TORC1 recruitment to lysosomes where TORC1 is activated by binding Rheb. How the absence of amino acids inactivates TORC1 is less well understood. Amino acid starvation recruits the TSC1/TSC2 complex to the vicinity of TORC1 to inhibit Rheb; however, the upstream mechanisms regulating TSC2 are not known. We identify here the eIF4A-containing eIF4F translation initiation complex as an upstream regulator of TSC2 in response to amino acid withdrawal in Drosophila We find that TORC1 and translation preinitiation complexes bind each other. Cells lacking eIF4F components retain elevated TORC1 activity upon amino acid removal. This effect is specific for eIF4F and not a general consequence of blocked translation. This study identifies specific components of the translation machinery as important mediators of TORC1 inactivation upon amino acid removal.
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Affiliation(s)
- Foivos-Filippos Tsokanos
- Division of Signal Transduction in Cancer and Metabolism, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Marie-Astrid Albert
- Division of Signal Transduction in Cancer and Metabolism, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Constantinos Demetriades
- Division of Signal Transduction in Cancer and Metabolism, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Kerstin Spirohn
- Department of Cell and Molecular Biology, Medical Faculty Mannheim, German Cancer Research Center (DKFZ), Division of Signaling and Functional Genomics and Heidelberg University, Heidelberg, Germany
| | - Michael Boutros
- Department of Cell and Molecular Biology, Medical Faculty Mannheim, German Cancer Research Center (DKFZ), Division of Signaling and Functional Genomics and Heidelberg University, Heidelberg, Germany
| | - Aurelio A Teleman
- Division of Signal Transduction in Cancer and Metabolism, German Cancer Research Center (DKFZ), Heidelberg, Germany
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119
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Lipid transfer and metabolism across the endolysosomal-mitochondrial boundary. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1861:880-894. [PMID: 26852832 DOI: 10.1016/j.bbalip.2016.02.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2015] [Revised: 01/30/2016] [Accepted: 02/03/2016] [Indexed: 01/10/2023]
Abstract
Lysosomes and mitochondria occupy a central stage in the maintenance of cellular homeostasis, by playing complementary roles in nutrient sensing and energy metabolism. Specifically, these organelles function as signaling hubs that integrate environmental and endogenous stimuli with specific metabolic responses. In particular, they control various lipid biosynthetic and degradative pipelines, either directly or indirectly, by regulating major cellular metabolic pathways, and by physical and functional connections established with each other and with other organelles. Membrane contact sites allow the exchange of ions and molecules between organelles, even without membrane fusion, and are privileged routes for lipid transfer among different membrane compartments. These inter-organellar connections typically involve the endoplasmic reticulum. Direct membrane contacts have now been described also between lysosomes, autophagosomes, lipid droplets, and mitochondria. This review focuses on these recently identified membrane contact sites, and on their role in lipid biosynthesis, exchange, turnover and catabolism. This article is part of a Special Issue entitled: The cellular lipid landscape edited by Tim P. Levine and Anant K. Menon.
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120
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The role of amino acid-induced mammalian target of rapamycin complex 1(mTORC1) signaling in insulin resistance. Exp Mol Med 2016; 48:e201. [PMID: 27534530 PMCID: PMC4686696 DOI: 10.1038/emm.2015.93] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Revised: 09/16/2015] [Accepted: 10/02/2015] [Indexed: 01/07/2023] Open
Abstract
Mammalian target of rapamycin (mTOR) controls cell growth and metabolism in response to nutrients, energy, and growth factors. Recent findings have placed the lysosome at the core of mTOR complex 1 (mTORC1) regulation by amino acids. Two parallel pathways, Rag GTPase-Ragulator and Vps34-phospholipase D1 (PLD1), regulate mTOR activation on the lysosome. This review describes the recent advances in understanding amino acid-induced mTOR signaling with a particular focus on the role of mTOR in insulin resistance.
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121
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Ko W, Kim S, Lee S, Jo K, Lee HS. Genetically encoded FRET sensors using a fluorescent unnatural amino acid as a FRET donor. RSC Adv 2016. [DOI: 10.1039/c6ra17375f] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
FRET sensors based on fluorescent proteins have been powerful tools for probing protein–protein interactions and structural changes within proteins.
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Affiliation(s)
- Wooseok Ko
- Department of Chemistry
- Sogang University
- Seoul 121-742
- Republic of Korea
| | - Sanggil Kim
- Department of Chemistry
- Sogang University
- Seoul 121-742
- Republic of Korea
| | - Seonghyun Lee
- Department of Chemistry
- Sogang University
- Seoul 121-742
- Republic of Korea
| | - Kyubong Jo
- Department of Chemistry
- Sogang University
- Seoul 121-742
- Republic of Korea
| | - Hyun Soo Lee
- Department of Chemistry
- Sogang University
- Seoul 121-742
- Republic of Korea
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122
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A Novel Interaction of Ecdysoneless (ECD) Protein with R2TP Complex Component RUVBL1 Is Required for the Functional Role of ECD in Cell Cycle Progression. Mol Cell Biol 2015; 36:886-99. [PMID: 26711270 DOI: 10.1128/mcb.00594-15] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Accepted: 12/18/2015] [Indexed: 12/21/2022] Open
Abstract
Ecdysoneless (ECD) is an evolutionarily conserved protein whose germ line deletion is embryonic lethal. Deletion of Ecd in cells causes cell cycle arrest, which is rescued by exogenous ECD, demonstrating a requirement of ECD for normal mammalian cell cycle progression. However, the exact mechanism by which ECD regulates cell cycle is unknown. Here, we demonstrate that ECD protein levels and subcellular localization are invariant during cell cycle progression, suggesting a potential role of posttranslational modifications or protein-protein interactions. Since phosphorylated ECD was recently shown to interact with the PIH1D1 adaptor component of the R2TP cochaperone complex, we examined the requirement of ECD phosphorylation in cell cycle progression. Notably, phosphorylation-deficient ECD mutants that failed to bind to PIH1D1 in vitro fully retained the ability to interact with the R2TP complex and yet exhibited a reduced ability to rescue Ecd-deficient cells from cell cycle arrest. Biochemical analyses demonstrated an additional phosphorylation-independent interaction of ECD with the RUVBL1 component of the R2TP complex, and this interaction is essential for ECD's cell cycle progression function. These studies demonstrate that interaction of ECD with RUVBL1, and its CK2-mediated phosphorylation, independent of its interaction with PIH1D1, are important for its cell cycle regulatory function.
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123
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Abstract
Mechanistic target of rapamycin (mTOR, also known as mammalian target of rapamycin) is a ubiquitous serine/threonine kinase that regulates cell growth, proliferation and survival. These effects are cell-type-specific, and are elicited in response to stimulation by growth factors, hormones and cytokines, as well as to internal and external metabolic cues. Rapamycin was initially developed as an inhibitor of T-cell proliferation and allograft rejection in the organ transplant setting. Subsequently, its molecular target (mTOR) was identified as a component of two interacting complexes, mTORC1 and mTORC2, that regulate T-cell lineage specification and macrophage differentiation. mTORC1 drives the proinflammatory expansion of T helper (TH) type 1, TH17, and CD4(-)CD8(-) (double-negative, DN) T cells. Both mTORC1 and mTORC2 inhibit the development of CD4(+)CD25(+)FoxP3(+) T regulatory (TREG) cells and, indirectly, mTORC2 favours the expansion of T follicular helper (TFH) cells which, similarly to DN T cells, promote B-cell activation and autoantibody production. In contrast to this proinflammatory effect of mTORC2, mTORC1 favours, to some extent, an anti-inflammatory macrophage polarization that is protective against infections and tissue inflammation. Outside the immune system, mTORC1 controls fibroblast proliferation and chondrocyte survival, with implications for tissue fibrosis and osteoarthritis, respectively. Rapamycin (which primarily inhibits mTORC1), ATP-competitive, dual mTORC1/mTORC2 inhibitors and upstream regulators of the mTOR pathway are being developed to treat autoimmune, hyperproliferative and degenerative diseases. In this regard, mTOR blockade promises to increase life expectancy through treatment and prevention of rheumatic diseases.
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Affiliation(s)
- Andras Perl
- Division of Rheumatology, Departments of Medicine, Microbiology and Immunology, and Biochemistry and Molecular Biology, State University of New York, Upstate Medical University, College of Medicine, 750 East Adams Street, Syracuse, New York 13210, USA
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124
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Xiong Y, Sheen J. Novel links in the plant TOR kinase signaling network. CURRENT OPINION IN PLANT BIOLOGY 2015; 28:83-91. [PMID: 26476687 PMCID: PMC4612364 DOI: 10.1016/j.pbi.2015.09.006] [Citation(s) in RCA: 100] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2015] [Revised: 09/18/2015] [Accepted: 09/25/2015] [Indexed: 05/18/2023]
Abstract
Nutrient and energy sensing and signaling mechanisms constitute the most ancient and fundamental regulatory networks to control growth and development in all life forms. The target of rapamycin (TOR) protein kinase is modulated by diverse nutrient, energy, hormone and stress inputs and plays a central role in regulating cell proliferation, growth, metabolism and stress responses from yeasts to plants and animals. Recent chemical, genetic, genomic and metabolomic analyses have enabled significant progress toward molecular understanding of the TOR signaling network in multicellular plants. This review discusses the applications of new chemical tools to probe plant TOR functions and highlights recent findings and predictions on TOR-mediate biological processes. Special focus is placed on novel and evolutionarily conserved TOR kinase effectors as positive and negative signaling regulators that control transcription, translation and metabolism to support cell proliferation, growth and maintenance from embryogenesis to senescence in the plant system.
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Affiliation(s)
- Yan Xiong
- Shanghai Center for Plant Stress Biology, Chinese Academy of Sciences, Shanghai 200032, PR China
| | - Jen Sheen
- Department of Genetics, Harvard Medical School, USA; Department of Molecular Biology and Center for Computational and Integrative Biology, Massachusetts General Hospital, MA 02114, USA.
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125
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Ye J, Palm W, Peng M, King B, Lindsten T, Li MO, Koumenis C, Thompson CB. GCN2 sustains mTORC1 suppression upon amino acid deprivation by inducing Sestrin2. Genes Dev 2015; 29:2331-6. [PMID: 26543160 PMCID: PMC4691887 DOI: 10.1101/gad.269324.115] [Citation(s) in RCA: 197] [Impact Index Per Article: 21.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Accepted: 10/22/2015] [Indexed: 12/31/2022]
Abstract
In this study, Ye et al. show that activation of GCN2, an amino acid-sensing kinase, during amino acid deprivation leads to ATF4-dependent transcription of the stress response protein Sestrin2. These results demonstrate an important link between GCN2 and mTORC1 signaling during amino acid homeostasis. Mammalian cells possess two amino acid-sensing kinases: general control nonderepressible 2 (GCN2) and mechanistic target of rapamycin complex 1 (mTORC1). Their combined effects orchestrate cellular adaptation to amino acid levels, but how their activities are coordinated remains poorly understood. Here, we demonstrate an important link between GCN2 and mTORC1 signaling. Upon deprivation of various amino acids, activated GCN2 up-regulates ATF4 to induce expression of the stress response protein Sestrin2, which is required to sustain repression of mTORC1 by blocking its lysosomal localization. Moreover, Sestrin2 induction is necessary for cell survival during glutamine deprivation, indicating that Sestrin2 is a critical effector of GCN2 signaling that regulates amino acid homeostasis through mTORC1 suppression.
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Affiliation(s)
- Jiangbin Ye
- Cancer Biology and Genetics Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA
| | - Wilhelm Palm
- Cancer Biology and Genetics Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA
| | - Min Peng
- Immunology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA
| | - Bryan King
- Cancer Biology and Genetics Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA
| | - Tullia Lindsten
- Immunology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA
| | - Ming O Li
- Immunology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA
| | - Constantinos Koumenis
- Department of Radiation Oncology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Craig B Thompson
- Cancer Biology and Genetics Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA
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126
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Liko D, Hall MN. mTOR in health and in sickness. J Mol Med (Berl) 2015; 93:1061-73. [DOI: 10.1007/s00109-015-1326-7] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2015] [Revised: 07/14/2015] [Accepted: 07/22/2015] [Indexed: 01/12/2023]
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127
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Plescher M, Teleman AA, Demetriades C. TSC2 mediates hyperosmotic stress-induced inactivation of mTORC1. Sci Rep 2015; 5:13828. [PMID: 26345496 PMCID: PMC4642562 DOI: 10.1038/srep13828] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Accepted: 08/06/2015] [Indexed: 02/07/2023] Open
Abstract
mTOR complex 1 (mTORC1) regulates cell growth and metabolism. mTORC1 activity is regulated via integration of positive growth-promoting stimuli and negative stress stimuli. One stress cells confront in physiological and pathophysiological contexts is hyperosmotic stress. The mechanism by which hyperosmotic stress regulates mTORC1 activity is not well understood. We show here that mild hyperosmotic stress induces a rapid and reversible inactivation of mTORC1 via a mechanism involving multiple upstream signaling pathways. We find that hyperosmotic stress causes dynamic changes in TSC2 phosphorylation by upstream kinases, such as Akt, thereby recruiting TSC2 from the cytoplasm to lysosomes where it acts on Rheb, the direct activator of mTORC1. This work puts together a signaling pathway whereby hyperosmotic stress inactivates mTORC1.
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Affiliation(s)
- Monika Plescher
- Division of Signal Transduction in Cancer and Metabolism, German Cancer Research Center (DKFZ), 69120, Heidelberg, Germany
| | - Aurelio A Teleman
- Division of Signal Transduction in Cancer and Metabolism, German Cancer Research Center (DKFZ), 69120, Heidelberg, Germany
| | - Constantinos Demetriades
- Division of Signal Transduction in Cancer and Metabolism, German Cancer Research Center (DKFZ), 69120, Heidelberg, Germany
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128
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Zaarur N, Xu X, Lestienne P, Meriin AB, McComb M, Costello CE, Newnam GP, Ganti R, Romanova NV, Shanmugasundaram M, Silva STN, Bandeiras TM, Matias PM, Lobachev KS, Lednev IK, Chernoff YO, Sherman MY. RuvbL1 and RuvbL2 enhance aggresome formation and disaggregate amyloid fibrils. EMBO J 2015; 34:2363-82. [PMID: 26303906 DOI: 10.15252/embj.201591245] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Accepted: 07/13/2015] [Indexed: 02/02/2023] Open
Abstract
The aggresome is an organelle that recruits aggregated proteins for storage and degradation. We performed an siRNA screen for proteins involved in aggresome formation and identified novel mammalian AAA+ protein disaggregases RuvbL1 and RuvbL2. Depletion of RuvbL1 or RuvbL2 suppressed aggresome formation and caused buildup of multiple cytoplasmic aggregates. Similarly, downregulation of RuvbL orthologs in yeast suppressed the formation of an aggresome-like body and enhanced the aggregate toxicity. In contrast, their overproduction enhanced the resistance to proteotoxic stress independently of chaperone Hsp104. Mammalian RuvbL associated with the aggresome, and the aggresome substrate synphilin-1 interacted directly with the RuvbL1 barrel-like structure near the opening of the central channel. Importantly, polypeptides with unfolded structures and amyloid fibrils stimulated the ATPase activity of RuvbL. Finally, disassembly of protein aggregates was promoted by RuvbL. These data indicate that RuvbL complexes serve as chaperones in protein disaggregation.
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Affiliation(s)
- Nava Zaarur
- Department of Biochemistry, Boston University School of Medicine, Boston, MA, USA
| | - Xiaobin Xu
- Center for Biomedical Mass Spectrometry, Boston University School of Medicine, Boston, MA, USA
| | | | - Anatoli B Meriin
- Department of Biochemistry, Boston University School of Medicine, Boston, MA, USA
| | - Mark McComb
- Center for Biomedical Mass Spectrometry, Boston University School of Medicine, Boston, MA, USA
| | - Catherine E Costello
- Department of Biochemistry, Boston University School of Medicine, Boston, MA, USA Center for Biomedical Mass Spectrometry, Boston University School of Medicine, Boston, MA, USA
| | - Gary P Newnam
- School of Biology, Georgia Institute of Technology, Atlanta, GA, USA
| | - Rakhee Ganti
- School of Biology, Georgia Institute of Technology, Atlanta, GA, USA
| | - Nina V Romanova
- Laboratory of Amyloid Biology and Institute of Translational Biomedicine, St. Petersburg State University, St. Petersburg, Russia
| | - Maruda Shanmugasundaram
- Department of Chemistry, University at Albany, State University of New York, Albany, NY, USA
| | - Sara T N Silva
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | | | - Pedro M Matias
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal Instituto de Biologia Experimental e Tecnológica, Oeiras, Portugal
| | - Kirill S Lobachev
- School of Biology, Georgia Institute of Technology, Atlanta, GA, USA
| | - Igor K Lednev
- Department of Chemistry, University at Albany, State University of New York, Albany, NY, USA
| | - Yury O Chernoff
- School of Biology, Georgia Institute of Technology, Atlanta, GA, USA Laboratory of Amyloid Biology and Institute of Translational Biomedicine, St. Petersburg State University, St. Petersburg, Russia
| | - Michael Y Sherman
- Department of Biochemistry, Boston University School of Medicine, Boston, MA, USA
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129
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Nezich CL, Wang C, Fogel AI, Youle RJ. MiT/TFE transcription factors are activated during mitophagy downstream of Parkin and Atg5. J Cell Biol 2015; 210:435-50. [PMID: 26240184 PMCID: PMC4523611 DOI: 10.1083/jcb.201501002] [Citation(s) in RCA: 219] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2015] [Accepted: 06/25/2015] [Indexed: 12/14/2022] Open
Abstract
The kinase PINK1 and ubiquitin ligase Parkin can regulate the selective elimination of damaged mitochondria through autophagy (mitophagy). Because of the demand on lysosomal function by mitophagy, we investigated a role for the transcription factor EB (TFEB), a master regulator of lysosomal biogenesis, in this process. We show that during mitophagy TFEB translocates to the nucleus and displays transcriptional activity in a PINK1- and Parkin-dependent manner. MITF and TFE3, homologues of TFEB belonging to the same microphthalmia/transcription factor E (MiT/TFE) family, are similarly regulated during mitophagy. Unlike TFEB translocation after starvation-induced mammalian target of rapamycin complex 1 inhibition, Parkin-mediated TFEB relocalization required Atg9A and Atg5 activity. However, constitutively active Rag guanosine triphosphatases prevented TFEB translocation during mitophagy, suggesting cross talk between these two MiT/TFE activation pathways. Analysis of clustered regularly interspaced short palindromic repeats-generated TFEB/MITF/TFE3/TFEC single, double, and triple knockout cell lines revealed that these proteins partly facilitate Parkin-mediated mitochondrial clearance. These results illuminate a pathway leading to MiT/TFE transcription factor activation, distinct from starvation-induced autophagy, which occurs during mitophagy.
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Affiliation(s)
- Catherine L Nezich
- Biochemistry Section, Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892
| | - Chunxin Wang
- Biochemistry Section, Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892
| | - Adam I Fogel
- Biochemistry Section, Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892
| | - Richard J Youle
- Biochemistry Section, Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892
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130
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The effect of concurrent training organisation in youth elite soccer players. Eur J Appl Physiol 2015; 115:2367-81. [DOI: 10.1007/s00421-015-3218-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2015] [Accepted: 07/05/2015] [Indexed: 10/23/2022]
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131
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Fonseca BD, Zakaria C, Jia JJ, Graber TE, Svitkin Y, Tahmasebi S, Healy D, Hoang HD, Jensen JM, Diao IT, Lussier A, Dajadian C, Padmanabhan N, Wang W, Matta-Camacho E, Hearnden J, Smith EM, Tsukumo Y, Yanagiya A, Morita M, Petroulakis E, González JL, Hernández G, Alain T, Damgaard CK. La-related Protein 1 (LARP1) Represses Terminal Oligopyrimidine (TOP) mRNA Translation Downstream of mTOR Complex 1 (mTORC1). J Biol Chem 2015; 290:15996-6020. [PMID: 25940091 PMCID: PMC4481205 DOI: 10.1074/jbc.m114.621730] [Citation(s) in RCA: 179] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Revised: 04/27/2015] [Indexed: 12/11/2022] Open
Abstract
The mammalian target of rapamycin complex 1 (mTORC1) is a critical regulator of protein synthesis. The best studied targets of mTORC1 in translation are the eukaryotic initiation factor-binding protein 1 (4E-BP1) and ribosomal protein S6 kinase 1 (S6K1). In this study, we identify the La-related protein 1 (LARP1) as a key novel target of mTORC1 with a fundamental role in terminal oligopyrimidine (TOP) mRNA translation. Recent genome-wide studies indicate that TOP and TOP-like mRNAs compose a large portion of the mTORC1 translatome, but the mechanism by which mTORC1 controls TOP mRNA translation is incompletely understood. Here, we report that LARP1 functions as a key repressor of TOP mRNA translation downstream of mTORC1. Our data show the following: (i) LARP1 associates with mTORC1 via RAPTOR; (ii) LARP1 interacts with TOP mRNAs in an mTORC1-dependent manner; (iii) LARP1 binds the 5'TOP motif to repress TOP mRNA translation; and (iv) LARP1 competes with the eukaryotic initiation factor (eIF) 4G for TOP mRNA binding. Importantly, from a drug resistance standpoint, our data also show that reducing LARP1 protein levels by RNA interference attenuates the inhibitory effect of rapamycin, Torin1, and amino acid deprivation on TOP mRNA translation. Collectively, our findings demonstrate that LARP1 functions as an important repressor of TOP mRNA translation downstream of mTORC1.
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Affiliation(s)
- Bruno D Fonseca
- From the Children's Hospital of Eastern Ontario Research Institute, Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario K1H 8L1, Canada,
| | - Chadi Zakaria
- the Department of Biochemistry, Rosalind and Morris Goodman Cancer Centre, McGill University, Montreal, Quebec H3A 1A3, Canada
| | - Jian-Jun Jia
- From the Children's Hospital of Eastern Ontario Research Institute, Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario K1H 8L1, Canada
| | - Tyson E Graber
- From the Children's Hospital of Eastern Ontario Research Institute, Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario K1H 8L1, Canada, the Department of Biochemistry, Rosalind and Morris Goodman Cancer Centre, McGill University, Montreal, Quebec H3A 1A3, Canada
| | - Yuri Svitkin
- the Department of Biochemistry, Rosalind and Morris Goodman Cancer Centre, McGill University, Montreal, Quebec H3A 1A3, Canada
| | - Soroush Tahmasebi
- the Department of Biochemistry, Rosalind and Morris Goodman Cancer Centre, McGill University, Montreal, Quebec H3A 1A3, Canada
| | - Danielle Healy
- From the Children's Hospital of Eastern Ontario Research Institute, Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario K1H 8L1, Canada
| | - Huy-Dung Hoang
- From the Children's Hospital of Eastern Ontario Research Institute, Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario K1H 8L1, Canada
| | - Jacob M Jensen
- the Department of Molecular Biology and Genetics, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Ilo T Diao
- the Department of Molecular Biology and Genetics, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Alexandre Lussier
- the Department of Biochemistry, Rosalind and Morris Goodman Cancer Centre, McGill University, Montreal, Quebec H3A 1A3, Canada
| | - Christopher Dajadian
- the Department of Biochemistry, Rosalind and Morris Goodman Cancer Centre, McGill University, Montreal, Quebec H3A 1A3, Canada
| | - Niranjan Padmanabhan
- the Department of Biochemistry, Rosalind and Morris Goodman Cancer Centre, McGill University, Montreal, Quebec H3A 1A3, Canada
| | - Walter Wang
- the Department of Biochemistry, Rosalind and Morris Goodman Cancer Centre, McGill University, Montreal, Quebec H3A 1A3, Canada
| | - Edna Matta-Camacho
- the Department of Biochemistry, Rosalind and Morris Goodman Cancer Centre, McGill University, Montreal, Quebec H3A 1A3, Canada
| | - Jaclyn Hearnden
- the Department of Biochemistry, Rosalind and Morris Goodman Cancer Centre, McGill University, Montreal, Quebec H3A 1A3, Canada
| | - Ewan M Smith
- the Medical Research Council Toxicology Unit, Hodgkin Building, Lancaster Road, Leicester LE1 9HN, United Kingdom
| | - Yoshinori Tsukumo
- the Department of Biochemistry, Rosalind and Morris Goodman Cancer Centre, McGill University, Montreal, Quebec H3A 1A3, Canada
| | - Akiko Yanagiya
- the Department of Biochemistry, Rosalind and Morris Goodman Cancer Centre, McGill University, Montreal, Quebec H3A 1A3, Canada
| | - Masahiro Morita
- the Department of Biochemistry, Rosalind and Morris Goodman Cancer Centre, McGill University, Montreal, Quebec H3A 1A3, Canada
| | - Emmanuel Petroulakis
- the Department of Biochemistry, Rosalind and Morris Goodman Cancer Centre, McGill University, Montreal, Quebec H3A 1A3, Canada, Pfizer Canada Inc., Kirkland, Quebec H9J 2M5, Canada, and
| | - Jose L González
- the Division of Basic Science, National Institute of Cancer, 22 San Fernando Ave., Tlalpan, Mexico City 14080, Mexico
| | - Greco Hernández
- the Division of Basic Science, National Institute of Cancer, 22 San Fernando Ave., Tlalpan, Mexico City 14080, Mexico
| | - Tommy Alain
- From the Children's Hospital of Eastern Ontario Research Institute, Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario K1H 8L1, Canada,
| | - Christian K Damgaard
- the Department of Molecular Biology and Genetics, Aarhus University, DK-8000 Aarhus C, Denmark,
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Abstract
Very few sports use only endurance or strength. Outside of running long distances on a flat surface and power-lifting, practically all sports require some combination of endurance and strength. Endurance and strength can be developed simultaneously to some degree. However, the development of a high level of endurance seems to prohibit the development or maintenance of muscle mass and strength. This interaction between endurance and strength is called the concurrent training effect. This review specifically defines the concurrent training effect, discusses the potential molecular mechanisms underlying this effect, and proposes strategies to maximize strength and endurance in the high-level athlete.
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Affiliation(s)
- Keith Baar
- Functional Molecular Biology Lab, Department of Neurobiology, Physiology, and Behavior, University of California Davis, One Shields Ave, 174 Briggs Hall, Davis, CA, 95616, USA,
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133
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Lorendeau D, Christen S, Rinaldi G, Fendt SM. Metabolic control of signalling pathways and metabolic auto-regulation. Biol Cell 2015; 107:251-72. [DOI: 10.1111/boc.201500015] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Accepted: 04/20/2015] [Indexed: 02/06/2023]
Affiliation(s)
- Doriane Lorendeau
- Vesalius Research Center; VIB; Leuven 3000 Belgium
- Department of Oncology; KU Leuven; Leuven 3000 Belgium
| | - Stefan Christen
- Vesalius Research Center; VIB; Leuven 3000 Belgium
- Department of Oncology; KU Leuven; Leuven 3000 Belgium
| | - Gianmarco Rinaldi
- Vesalius Research Center; VIB; Leuven 3000 Belgium
- Department of Oncology; KU Leuven; Leuven 3000 Belgium
| | - Sarah-Maria Fendt
- Vesalius Research Center; VIB; Leuven 3000 Belgium
- Department of Oncology; KU Leuven; Leuven 3000 Belgium
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134
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Gaubitz C, Oliveira TM, Prouteau M, Leitner A, Karuppasamy M, Konstantinidou G, Rispal D, Eltschinger S, Robinson GC, Thore S, Aebersold R, Schaffitzel C, Loewith R. Molecular Basis of the Rapamycin Insensitivity of Target Of Rapamycin Complex 2. Mol Cell 2015; 58:977-88. [PMID: 26028537 DOI: 10.1016/j.molcel.2015.04.031] [Citation(s) in RCA: 105] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Revised: 03/31/2015] [Accepted: 04/22/2015] [Indexed: 10/23/2022]
Abstract
Target of Rapamycin (TOR) plays central roles in the regulation of eukaryote growth as the hub of two essential multiprotein complexes: TORC1, which is rapamycin-sensitive, and the lesser characterized TORC2, which is not. TORC2 is a key regulator of lipid biosynthesis and Akt-mediated survival signaling. In spite of its importance, its structure and the molecular basis of its rapamycin insensitivity are unknown. Using crosslinking-mass spectrometry and electron microscopy, we determined the architecture of TORC2. TORC2 displays a rhomboid shape with pseudo-2-fold symmetry and a prominent central cavity. Our data indicate that the C-terminal part of Avo3, a subunit unique to TORC2, is close to the FKBP12-rapamycin-binding domain of Tor2. Removal of this sequence generated a FKBP12-rapamycin-sensitive TORC2 variant, which provides a powerful tool for deciphering TORC2 function in vivo. Using this variant, we demonstrate a role for TORC2 in G2/M cell-cycle progression.
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Affiliation(s)
- Christl Gaubitz
- Department of Molecular Biology and Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, 30 Quai Ernest Ansermet, CH1211 Geneva, Switzerland
| | - Taiana M Oliveira
- European Molecular Biology Laboratory, Grenoble Outstation, 71 Avenue des Martyrs, 38042 Grenoble, France; Fondation ARC, 9 rue Guy Môquet, BP 90003, 04803 Villejuif Cedex, France
| | - Manoel Prouteau
- Department of Molecular Biology and Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, 30 Quai Ernest Ansermet, CH1211 Geneva, Switzerland
| | - Alexander Leitner
- Department of Biology, Institute of Molecular Systems Biology, ETH Zürich, 8093 Zürich, Switzerland
| | - Manikandan Karuppasamy
- European Molecular Biology Laboratory, Grenoble Outstation, 71 Avenue des Martyrs, 38042 Grenoble, France
| | - Georgia Konstantinidou
- Department of Molecular Biology and Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, 30 Quai Ernest Ansermet, CH1211 Geneva, Switzerland
| | - Delphine Rispal
- Department of Molecular Biology and Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, 30 Quai Ernest Ansermet, CH1211 Geneva, Switzerland
| | - Sandra Eltschinger
- Department of Molecular Biology and Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, 30 Quai Ernest Ansermet, CH1211 Geneva, Switzerland
| | - Graham C Robinson
- Department of Molecular Biology and Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, 30 Quai Ernest Ansermet, CH1211 Geneva, Switzerland
| | - Stéphane Thore
- Department of Molecular Biology and Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, 30 Quai Ernest Ansermet, CH1211 Geneva, Switzerland; University of Bordeaux, European Institute for Chemistry and Biology, ARNA Laboratory, F-33607 Pessac, France; Institut National de la Santé Et de la Recherche Médicale, INSERM-U869, ARNA Laboratory, F-33000, Bordeaux, France
| | - Ruedi Aebersold
- Department of Biology, Institute of Molecular Systems Biology, ETH Zürich, 8093 Zürich, Switzerland; Faculty of Science, University of Zürich, 8057 Zürich, Switzerland
| | - Christiane Schaffitzel
- European Molecular Biology Laboratory, Grenoble Outstation, 71 Avenue des Martyrs, 38042 Grenoble, France; School of Biochemistry, University of Bristol, Bristol, BS8 1TD, United Kingdom.
| | - Robbie Loewith
- Department of Molecular Biology and Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, 30 Quai Ernest Ansermet, CH1211 Geneva, Switzerland; National Centre of Competence in Research "Chemical Biology," University of Geneva, Geneva CH-1211, Switzerland.
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135
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de Cavanagh EMV, Inserra F, Ferder L. Angiotensin II blockade: how its molecular targets may signal to mitochondria and slow aging. Coincidences with calorie restriction and mTOR inhibition. Am J Physiol Heart Circ Physiol 2015; 309:H15-44. [PMID: 25934099 DOI: 10.1152/ajpheart.00459.2014] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Accepted: 04/30/2015] [Indexed: 02/07/2023]
Abstract
Caloric restriction (CR), renin angiotensin system blockade (RAS-bl), and rapamycin-mediated mechanistic target of rapamycin (mTOR) inhibition increase survival and retard aging across species. Previously, we have summarized CR and RAS-bl's converging effects, and the mitochondrial function changes associated with their physiological benefits. mTOR inhibition and enhanced sirtuin and KLOTHO signaling contribute to the benefits of CR in aging. mTORC1/mTORC2 complexes contribute to cell growth and metabolic regulation. Prolonged mTORC1 activation may lead to age-related disease progression; thus, rapamycin-mediated mTOR inhibition and CR may extend lifespan and retard aging through mTORC1 interference. Sirtuins by deacetylating histone and transcription-related proteins modulate signaling and survival pathways and mitochondrial functioning. CR regulates several mammalian sirtuins favoring their role in aging regulation. KLOTHO/fibroblast growth factor 23 (FGF23) contribute to control Ca(2+), phosphate, and vitamin D metabolism, and their dysregulation may participate in age-related disease. Here we review how mTOR inhibition extends lifespan, how KLOTHO functions as an aging suppressor, how sirtuins mediate longevity, how vitamin D loss may contribute to age-related disease, and how they relate to mitochondrial function. Also, we discuss how RAS-bl downregulates mTOR and upregulates KLOTHO, sirtuin, and vitamin D receptor expression, suggesting that at least some of RAS-bl benefits in aging are mediated through the modulation of mTOR, KLOTHO, and sirtuin expression and vitamin D signaling, paralleling CR actions in age retardation. Concluding, the available evidence endorses the idea that RAS-bl is among the interventions that may turn out to provide relief to the spreading issue of age-associated chronic disease.
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Affiliation(s)
- Elena M V de Cavanagh
- Center of Hypertension, Cardiology Department, Austral University Hospital, Derqui, Argentina; School of Biomedical Sciences, Austral University, Buenos Aires, Argentina; and
| | - Felipe Inserra
- Center of Hypertension, Cardiology Department, Austral University Hospital, Derqui, Argentina; School of Biomedical Sciences, Austral University, Buenos Aires, Argentina; and
| | - León Ferder
- Department of Physiology and Pharmacology, Ponce School of Medicine, Ponce, Puerto Rico
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136
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Xu T, Nicolson S, Denton D, Kumar S. Distinct requirements of Autophagy-related genes in programmed cell death. Cell Death Differ 2015; 22:1792-802. [PMID: 25882046 DOI: 10.1038/cdd.2015.28] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Revised: 02/06/2015] [Accepted: 02/23/2015] [Indexed: 12/30/2022] Open
Abstract
Although most programmed cell death (PCD) during animal development occurs by caspase-dependent apoptosis, autophagy-dependent cell death is also important in specific contexts. In previous studies, we established that PCD of the obsolete Drosophila larval midgut tissue is dependent on autophagy and can occur in the absence of the main components of the apoptotic pathway. As autophagy is primarily a survival mechanism in response to stress such as starvation, it is currently unclear if the regulation and mechanism of autophagy as a pro-death pathway is distinct to that as pro-survival. To establish the requirement of the components of the autophagy pathway during cell death, we examined the effect of systematically knocking down components of the autophagy machinery on autophagy induction and timing of midgut PCD. We found that there is a distinct requirement of the individual components of the autophagy pathway in a pro-death context. Furthermore, we show that TORC1 is upstream of autophagy induction in the midgut indicating that while the machinery may be distinct the activation may occur similarly in PCD and during starvation-induced autophagy signalling. Our data reveal that while autophagy initiation occurs similarly in different cellular contexts, there is a tissue/function-specific requirement for the components of the autophagic machinery.
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Affiliation(s)
- T Xu
- Centre for Cancer Biology, University of South Australia, Adelaide, SA 5001, Australia
| | - S Nicolson
- Centre for Cancer Biology, University of South Australia, Adelaide, SA 5001, Australia
| | - D Denton
- Centre for Cancer Biology, University of South Australia, Adelaide, SA 5001, Australia
| | - S Kumar
- Centre for Cancer Biology, University of South Australia, Adelaide, SA 5001, Australia
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137
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Heberle AM, Prentzell MT, van Eunen K, Bakker BM, Grellscheid SN, Thedieck K. Molecular mechanisms of mTOR regulation by stress. Mol Cell Oncol 2015; 2:e970489. [PMID: 27308421 PMCID: PMC4904989 DOI: 10.4161/23723548.2014.970489] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2014] [Revised: 09/12/2014] [Accepted: 09/13/2014] [Indexed: 04/12/2023]
Abstract
Tumors are prime examples of cell growth in unfavorable environments that elicit cellular stress. The high metabolic demand and insufficient vascularization of tumors cause a deficiency of oxygen and nutrients. Oncogenic mutations map to signaling events via mammalian target of rapamycin (mTOR), metabolic pathways, and mitochondrial function. These alterations have been linked with cellular stresses, in particular endoplasmic reticulum (ER) stress, hypoxia, and oxidative stress. Yet tumors survive these challenges and acquire highly energy-demanding traits, such as overgrowth and invasiveness. In this review we focus on stresses that occur in cancer cells and discuss them in the context of mTOR signaling. Of note, many tumor traits require mTOR complex 1 (mTORC1) activity, but mTORC1 hyperactivation eventually sensitizes cells to apoptosis. Thus, mTORC1 activity needs to be balanced in cancer cells. We provide an overview of the mechanisms contributing to mTOR regulation by stress and suggest a model wherein stress granules function as guardians of mTORC1 signaling, allowing cancer cells to escape stress-induced cell death.
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Affiliation(s)
- Alexander Martin Heberle
- Department of Pediatrics and Centre for Systems Biology of Energy Metabolism and Ageing; University of Groningen; University Medical Center Groningen (UMCG); Groningen, The Netherlands
| | - Mirja Tamara Prentzell
- Department of Pediatrics and Centre for Systems Biology of Energy Metabolism and Ageing; University of Groningen; University Medical Center Groningen (UMCG); Groningen, The Netherlands
- Faculty of Biology; Institute for Biology 3; Albert-Ludwigs-University Freiburg; Freiburg, Germany
- Spemann Graduate School of Biology and Medicine (SGBM); University of Freiburg; Freiburg, Germany
| | - Karen van Eunen
- Department of Pediatrics and Centre for Systems Biology of Energy Metabolism and Ageing; University of Groningen; University Medical Center Groningen (UMCG); Groningen, The Netherlands
- Top Institute Food and Nutrition; Wageningen, The Netherlands
| | - Barbara Marleen Bakker
- Department of Pediatrics and Centre for Systems Biology of Energy Metabolism and Ageing; University of Groningen; University Medical Center Groningen (UMCG); Groningen, The Netherlands
| | | | - Kathrin Thedieck
- Department of Pediatrics and Centre for Systems Biology of Energy Metabolism and Ageing; University of Groningen; University Medical Center Groningen (UMCG); Groningen, The Netherlands
- Faculty of Biology; Institute for Biology 3; Albert-Ludwigs-University Freiburg; Freiburg, Germany
- School of Medicine and Health Sciences; Carl von Ossietzky University Oldenburg; Oldenburg, Germany
- BIOSS Centre for Biological Signaling Studies; Albert-Ludwigs-University Freiburg; Freiburg, Germany
- Correspondence to: Kathrin Thedieck; E-mail: ;
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138
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Tanaka K, Sasayama T, Irino Y, Takata K, Nagashima H, Satoh N, Kyotani K, Mizowaki T, Imahori T, Ejima Y, Masui K, Gini B, Yang H, Hosoda K, Sasaki R, Mischel PS, Kohmura E. Compensatory glutamine metabolism promotes glioblastoma resistance to mTOR inhibitor treatment. J Clin Invest 2015; 125:1591-602. [PMID: 25798620 DOI: 10.1172/jci78239] [Citation(s) in RCA: 172] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Accepted: 02/05/2015] [Indexed: 12/24/2022] Open
Abstract
The mechanistic target of rapamycin (mTOR) is hyperactivated in many types of cancer, rendering it a compelling drug target; however, the impact of mTOR inhibition on metabolic reprogramming in cancer is incompletely understood. Here, by integrating metabolic and functional studies in glioblastoma multiforme (GBM) cell lines, preclinical models, and clinical samples, we demonstrate that the compensatory upregulation of glutamine metabolism promotes resistance to mTOR kinase inhibitors. Metabolomic studies in GBM cells revealed that glutaminase (GLS) and glutamate levels are elevated following mTOR kinase inhibitor treatment. Moreover, these mTOR inhibitor-dependent metabolic alterations were confirmed in a GBM xenograft model. Expression of GLS following mTOR inhibitor treatment promoted GBM survival in an α-ketoglutarate-dependent (αKG-dependent) manner. Combined genetic and/or pharmacological inhibition of mTOR kinase and GLS resulted in massive synergistic tumor cell death and growth inhibition in tumor-bearing mice. These results highlight a critical role for compensatory glutamine metabolism in promoting mTOR inhibitor resistance and suggest that rational combination therapy has the potential to suppress resistance.
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139
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von Morgen P, Hořejší Z, Macurek L. Substrate recognition and function of the R2TP complex in response to cellular stress. Front Genet 2015; 6:69. [PMID: 25767478 PMCID: PMC4341119 DOI: 10.3389/fgene.2015.00069] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Accepted: 02/10/2015] [Indexed: 11/18/2022] Open
Abstract
The R2TP complex is a HSP90 co-chaperone, which consists of four subunits: PIH1D1, RPAP3, RUVBL1, and RUVBL2. It is involved in the assembly of large protein or protein–RNA complexes such as RNA polymerase, small nucleolar ribonucleoproteins (snoRNPs), phosphatidylinositol 3 kinase-related kinases (PIKKs), and their complexes. While RPAP3 has a HSP90 binding domain and the RUVBLs comprise ATPase activities important for R2TP functions, PIH1D1 contains a PIH-N domain that specifically recognizes phosphorylated substrates of the R2TP complex. In this review we provide an overview of the current knowledge of the R2TP complex with the focus on the recently identified structural and mechanistic features of the R2TP complex functions. We also discuss the way R2TP regulates cellular response to stress caused by low levels of nutrients or by DNA damage and its possible exploitation as a target for anti-cancer therapy.
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Affiliation(s)
- Patrick von Morgen
- Department of Cancer Cell Biology, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Prague Czech Republic
| | - Zuzana Hořejší
- Department of Cancer Cell Biology, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Prague Czech Republic ; DNA Damage Response Laboratory, London Research Institute, London UK
| | - Libor Macurek
- Department of Cancer Cell Biology, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Prague Czech Republic
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140
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Baena M, Sangüesa G, Hutter N, Sánchez RM, Roglans N, Laguna JC, Alegret M. Fructose supplementation impairs rat liver autophagy through mTORC activation without inducing endoplasmic reticulum stress. Biochim Biophys Acta Mol Cell Biol Lipids 2015; 1851:107-16. [DOI: 10.1016/j.bbalip.2014.11.003] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Revised: 10/14/2014] [Accepted: 11/04/2014] [Indexed: 01/13/2023]
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141
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Jewell JL, Kim YC, Russell RC, Yu FX, Park HW, Plouffe SW, Tagliabracci VS, Guan KL. Metabolism. Differential regulation of mTORC1 by leucine and glutamine. Science 2015; 347:194-8. [PMID: 25567907 PMCID: PMC4384888 DOI: 10.1126/science.1259472] [Citation(s) in RCA: 535] [Impact Index Per Article: 59.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The mechanistic target of rapamycin (mTOR) complex 1 (mTORC1) integrates environmental and intracellular signals to regulate cell growth. Amino acids stimulate mTORC1 activation at the lysosome in a manner thought to be dependent on the Rag small guanosine triphosphatases (GTPases), the Ragulator complex, and the vacuolar H+-adenosine triphosphatase (v-ATPase). We report that leucine and glutamine stimulate mTORC1 by Rag GTPase-dependent and -independent mechanisms, respectively. Glutamine promoted mTORC1 translocation to the lysosome in RagA and RagB knockout cells and required the v-ATPase but not the Ragulator. Furthermore, we identified the adenosine diphosphate ribosylation factor-1 GTPase to be required for mTORC1 activation and lysosomal localization by glutamine. Our results uncover a signaling cascade to mTORC1 activation independent of the Rag GTPases and suggest that mTORC1 is differentially regulated by specific amino acids.
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Affiliation(s)
- Jenna L Jewell
- Department of Pharmacology and Moores Cancer Center, University of California, San Diego, La Jolla, CA 92093, USA
| | - Young Chul Kim
- Department of Pharmacology and Moores Cancer Center, University of California, San Diego, La Jolla, CA 92093, USA
| | - Ryan C Russell
- Department of Pharmacology and Moores Cancer Center, University of California, San Diego, La Jolla, CA 92093, USA
| | - Fa-Xing Yu
- Children's Hospital and Institute of Biomedical Sciences, Fudan University, Shanghai 200032, China
| | - Hyun Woo Park
- Department of Pharmacology and Moores Cancer Center, University of California, San Diego, La Jolla, CA 92093, USA
| | - Steven W Plouffe
- Department of Pharmacology and Moores Cancer Center, University of California, San Diego, La Jolla, CA 92093, USA
| | - Vincent S Tagliabracci
- Department of Pharmacology and Moores Cancer Center, University of California, San Diego, La Jolla, CA 92093, USA
| | - Kun-Liang Guan
- Department of Pharmacology and Moores Cancer Center, University of California, San Diego, La Jolla, CA 92093, USA.
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142
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Gomes AP, Blenis J. A nexus for cellular homeostasis: the interplay between metabolic and signal transduction pathways. Curr Opin Biotechnol 2015; 34:110-7. [PMID: 25562138 DOI: 10.1016/j.copbio.2014.12.007] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2014] [Revised: 12/08/2014] [Accepted: 12/10/2014] [Indexed: 12/21/2022]
Abstract
In multicellular organisms, individual cells have evolved to sense external and internal cues in order to maintain cellular homeostasis and survive under different environmental conditions. Cells efficiently adjust their metabolism to reflect the abundance of nutrients, energy and growth factors. The ability to rewire cellular metabolism between anabolic and catabolic processes is crucial for cells to thrive. Thus, cells have developed, through evolution, metabolic networks that are highly plastic and tightly regulated to meet the requirements necessary to maintain cellular homeostasis. The plasticity of these cellular systems is tightly regulated by complex signaling networks that integrate the intracellular and extracellular information. The coordination of signal transduction and metabolic pathways is essential in maintaining a healthy and rapidly responsive cellular state.
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Affiliation(s)
- Ana P Gomes
- Meyer Cancer Center, Weill Cornell Medical College, New York, NY, USA; Department of Pharmacology, Weill Cornell Medical College, New York, NY, USA; Department of Cell Biology, Harvard Medical School, Boston, MA, USA
| | - John Blenis
- Meyer Cancer Center, Weill Cornell Medical College, New York, NY, USA; Department of Pharmacology, Weill Cornell Medical College, New York, NY, USA; Department of Cell Biology, Harvard Medical School, Boston, MA, USA.
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143
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Laxman S, Sutter BM, Shi L, Tu BP. Npr2 inhibits TORC1 to prevent inappropriate utilization of glutamine for biosynthesis of nitrogen-containing metabolites. Sci Signal 2014; 7:ra120. [PMID: 25515537 DOI: 10.1126/scisignal.2005948] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Cells must be capable of switching between growth and autophagy in unpredictable nutrient environments. The conserved Npr2 protein complex (comprising Iml1, Npr2, and Npr3; also called SEACIT) inhibits target of rapamycin complex 1 (TORC1) kinase signaling, which inhibits autophagy in nutrient-rich conditions. In yeast cultured in media with nutrient limitations that promote autophagy and inhibit growth, loss of Npr2 enables cells to bypass autophagy and proliferate. We determined that Npr2-deficient yeast had a metabolic state distinct from that of wild-type yeast when grown in minimal media containing ammonium as a nitrogen source and a nonfermentable carbon source (lactate). Unlike wild-type yeast, which accumulated glutamine, Npr2-deficient yeast metabolized glutamine into nitrogen-containing metabolites and maintained a high concentration of S-adenosyl methionine (SAM). Moreover, in wild-type yeast grown in these nutrient-limited conditions, supplementation with methionine stimulated glutamine consumption for synthesis of nitrogenous metabolites, demonstrating integration of a sulfur-containing amino acid cue and nitrogen utilization. These data revealed the metabolic basis by which the Npr2 complex regulates cellular homeostasis and demonstrated a key function for TORC1 in regulating the synthesis and utilization of glutamine as a nitrogen source.
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Affiliation(s)
- Sunil Laxman
- Department of Biochemistry, The University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390-9038, USA
| | - Benjamin M Sutter
- Department of Biochemistry, The University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390-9038, USA
| | - Lei Shi
- Department of Biochemistry, The University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390-9038, USA
| | - Benjamin P Tu
- Department of Biochemistry, The University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390-9038, USA.
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144
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Jain A, Arauz E, Aggarwal V, Ikon N, Chen J, Ha T. Stoichiometry and assembly of mTOR complexes revealed by single-molecule pulldown. Proc Natl Acad Sci U S A 2014; 111:17833-8. [PMID: 25453101 PMCID: PMC4273350 DOI: 10.1073/pnas.1419425111] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The mammalian target of rapamycin (mTOR) kinase is a master regulator of cellular, developmental, and metabolic processes. Deregulation of mTOR signaling is implicated in numerous human diseases including cancer and diabetes. mTOR functions as part of either of the two multisubunit complexes, mTORC1 and mTORC2, but molecular details about the assembly and oligomerization of mTORCs are currently lacking. We use the single-molecule pulldown (SiMPull) assay that combines principles of conventional pulldown assays with single-molecule fluorescence microscopy to investigate the stoichiometry and assembly of mTORCs. After validating our approach with mTORC1, confirming a dimeric assembly as previously reported, we show that all major components of mTORC2 exist in two copies per complex, indicating that mTORC2 assembles as a homodimer. Interestingly, each mTORC component, when free from the complexes, is present as a monomer and no single subunit serves as the dimerizing component. Instead, our data suggest that dimerization of mTORCs is the result of multiple subunits forming a composite surface. SiMPull also allowed us to distinguish complex disassembly from stoichiometry changes. Physiological conditions that abrogate mTOR signaling such as nutrient deprivation or energy stress did not alter the stoichiometry of mTORCs. On the other hand, rapamycin treatment leads to transient appearance of monomeric mTORC1 before complete disruption of the mTOR-raptor interaction, whereas mTORC2 stoichiometry is unaffected. These insights into assembly of mTORCs may guide future mechanistic studies and exploration of therapeutic potential.
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Affiliation(s)
- Ankur Jain
- Center for Biophysics and Computational Biology, Institute for Genomic Biology
| | - Edwin Arauz
- Department of Cell and Developmental Biology
| | - Vasudha Aggarwal
- Center for Biophysics and Computational Biology, Institute for Genomic Biology
| | - Nikita Ikon
- Department of Cell and Developmental Biology
| | - Jie Chen
- Department of Cell and Developmental Biology,
| | - Taekjip Ha
- Center for Biophysics and Computational Biology, Institute for Genomic Biology, Department of Physics, and Howard Hughes Medical Institute, University of Illinois at Urbana-Champaign, Urbana, IL 61801
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145
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Regulation of rDNA transcription in response to growth factors, nutrients and energy. Gene 2014; 556:27-34. [PMID: 25447905 DOI: 10.1016/j.gene.2014.11.010] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2014] [Revised: 11/04/2014] [Accepted: 11/06/2014] [Indexed: 11/21/2022]
Abstract
Exquisite control of ribosome biogenesis is fundamental for the maintenance of cellular growth and proliferation. Importantly, synthesis of ribosomal RNA by RNA polymerase I is a key regulatory step in ribosome biogenesis and a major biosynthetic and energy consuming process. Consequently, ribosomal RNA gene transcription is tightly coupled to the availability of growth factors, nutrients and energy. Thus cells have developed an intricate sensing network to monitor the cellular environment and modulate ribosomal DNA transcription accordingly. Critical controllers in these sensing networks, which mediate growth factor activation of ribosomal DNA transcription, include the PI3K/AKT/mTORC1, RAS/RAF/ERK pathways and MYC transcription factor. mTORC1 also responds to amino acids and energy status, making it a key hub linking all three stimuli to the regulation of ribosomal DNA transcription, although this is achieved via overlapping and distinct mechanisms. This review outlines the current knowledge of how cells respond to environmental cues to control ribosomal RNA synthesis. We also highlight the critical points within this network that are providing new therapeutic opportunities for treating cancers through modulation of RNA polymerase I activity and potential novel imaging strategies.
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146
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Roberts DJ, Miyamoto S. Hexokinase II integrates energy metabolism and cellular protection: Akting on mitochondria and TORCing to autophagy. Cell Death Differ 2014; 22:248-57. [PMID: 25323588 DOI: 10.1038/cdd.2014.173] [Citation(s) in RCA: 279] [Impact Index Per Article: 27.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Revised: 09/11/2014] [Accepted: 09/15/2014] [Indexed: 01/08/2023] Open
Abstract
Accumulating evidence reveals that metabolic and cell survival pathways are closely related, sharing common signaling molecules. Hexokinase catalyzes the phosphorylation of glucose, the rate-limiting first step of glycolysis. Hexokinase II (HK-II) is a predominant isoform in insulin-sensitive tissues such as heart, skeletal muscle, and adipose tissues. It is also upregulated in many types of tumors associated with enhanced aerobic glycolysis in tumor cells, the Warburg effect. In addition to the fundamental role in glycolysis, HK-II is increasingly recognized as a component of a survival signaling nexus. This review summarizes recent advances in understanding the protective role of HK-II, controlling cellular growth, preventing mitochondrial death pathway and enhancing autophagy, with a particular focus on the interaction between HK-II and Akt/mTOR pathway to integrate metabolic status with the control of cell survival.
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Affiliation(s)
- D J Roberts
- Department of Pharmacology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, USA
| | - S Miyamoto
- Department of Pharmacology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, USA
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147
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Medvetz D, Priolo C, Henske EP. Therapeutic targeting of cellular metabolism in cells with hyperactive mTORC1: a paradigm shift. Mol Cancer Res 2014; 13:3-8. [PMID: 25298408 DOI: 10.1158/1541-7786.mcr-14-0343] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
mTORC1 is an established master regulator of cellular metabolic homeostasis, via multiple mechanisms that include altered glucose and glutamine metabolism, and decreased autophagy. mTORC1 is hyperactive in the human disease tuberous sclerosis complex (TSC), an autosomal dominant disorder caused by germline mutations in the TSC1 or TSC2 gene. In TSC-deficient cells, metabolic wiring is extensively disrupted and rerouted as a consequence of mTORC1 hyperactivation, leading to multiple vulnerabilities, including "addiction" to glutamine, glucose, and autophagy. There is synergy between two rapidly evolving trajectories: elucidating the metabolic vulnerabilities of TSC-associated tumor cells, and the development of therapeutic agents that selectively target cancer-associated metabolic defects. The current review focuses on recent work supporting the targeting of cellular metabolic dysregulation for the treatment of tumors in TSC, with relevance to the many other human neoplasms with mTORC1 hyperactivation. These data expose a fundamental paradox in the therapeutic targeting of tumor cells with hyperactive mTORC1: inhibition of mTORC1 may not represent the optimal therapeutic strategy. Inhibiting mTORC1 "fixes" the metabolic vulnerabilities, results in a cytostatic response, and closes the door to metabolic targeting. In contrast, leaving mTORC1 active allows the metabolic vulnerabilities to be targeted with the potential for a cytocidal cellular response. The insights provided here suggest that therapeutic strategies for TSC and other tumors with activation of mTORC1 are at the verge of a major paradigm shift, in which optimal clinical responses will be accomplished by targeting mTORC1-associated metabolic vulnerabilities without inhibiting mTORC1 itself.
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Affiliation(s)
- Doug Medvetz
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts
| | - Carmen Priolo
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts.
| | - Elizabeth P Henske
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts.
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148
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Csibi A, Lee G, Yoon SO, Tong H, Ilter D, Elia I, Fendt SM, Roberts TM, Blenis J. The mTORC1/S6K1 pathway regulates glutamine metabolism through the eIF4B-dependent control of c-Myc translation. Curr Biol 2014; 24:2274-80. [PMID: 25220053 DOI: 10.1016/j.cub.2014.08.007] [Citation(s) in RCA: 195] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2013] [Revised: 07/12/2014] [Accepted: 08/05/2014] [Indexed: 12/13/2022]
Abstract
Growth-promoting signaling molecules, including the mammalian target of rapamycin complex 1 (mTORC1), drive the metabolic reprogramming of cancer cells required to support their biosynthetic needs for rapid growth and proliferation. Glutamine is catabolyzed to α-ketoglutarate (αKG), a tricarboxylic acid (TCA) cycle intermediate, through two deamination reactions, the first requiring glutaminase (GLS) to generate glutamate and the second occurring via glutamate dehydrogenase (GDH) or transaminases. Activation of the mTORC1 pathway has been shown previously to promote the anaplerotic entry of glutamine to the TCA cycle via GDH. Moreover, mTORC1 activation also stimulates the uptake of glutamine, but the mechanism is unknown. It is generally thought that rates of glutamine utilization are limited by mitochondrial uptake via GLS, suggesting that, in addition to GDH, mTORC1 could regulate GLS. Here we demonstrate that mTORC1 positively regulates GLS and glutamine flux through this enzyme. We show that mTORC1 controls GLS levels through the S6K1-dependent regulation of c-Myc (Myc). Molecularly, S6K1 enhances Myc translation efficiency by modulating the phosphorylation of eukaryotic initiation factor eIF4B, which is critical to unwind its structured 5' untranslated region (5'UTR). Finally, our data show that the pharmacological inhibition of GLS is a promising target in pancreatic cancers expressing low levels of PTEN.
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Affiliation(s)
- Alfredo Csibi
- Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA
| | - Gina Lee
- Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA
| | - Sang-Oh Yoon
- Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA
| | - Haoxuan Tong
- Department of Cancer Biology, Dana Farber Cancer Institute and Harvard Medical School, Boston, MA 02115, USA
| | - Didem Ilter
- Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA; Department of Pharmacology, Meyer Cancer Center, Weill Cornell Medical College, New York, NY 10065, USA
| | - Ilaria Elia
- Flemish Institute of Biotechnology (VIB), Vesalius Research Center, Herestraat 49, 3000 Leuven, Belgium; Department of Oncology, KU Leuven-University of Leuven, Herestraat 49, 3000 Leuven, Belgium
| | - Sarah-Maria Fendt
- Flemish Institute of Biotechnology (VIB), Vesalius Research Center, Herestraat 49, 3000 Leuven, Belgium; Department of Oncology, KU Leuven-University of Leuven, Herestraat 49, 3000 Leuven, Belgium
| | - Thomas M Roberts
- Department of Cancer Biology, Dana Farber Cancer Institute and Harvard Medical School, Boston, MA 02115, USA
| | - John Blenis
- Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA; Department of Pharmacology, Meyer Cancer Center, Weill Cornell Medical College, New York, NY 10065, USA.
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149
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Cytosolic pH Regulates Cell Growth through Distinct GTPases, Arf1 and Gtr1, to Promote Ras/PKA and TORC1 Activity. Mol Cell 2014; 55:409-21. [DOI: 10.1016/j.molcel.2014.06.002] [Citation(s) in RCA: 95] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Revised: 02/14/2014] [Accepted: 05/20/2014] [Indexed: 12/14/2022]
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150
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Hepatic mTORC1 controls locomotor activity, body temperature, and lipid metabolism through FGF21. Proc Natl Acad Sci U S A 2014; 111:11592-9. [PMID: 25082895 DOI: 10.1073/pnas.1412047111] [Citation(s) in RCA: 121] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
The liver is a key metabolic organ that controls whole-body physiology in response to nutrient availability. Mammalian target of rapamycin (mTOR) is a nutrient-activated kinase and central controller of growth and metabolism that is negatively regulated by the tumor suppressor tuberous sclerosis complex 1 (TSC1). To investigate the role of hepatic mTOR complex 1 (mTORC1) in whole-body physiology, we generated liver-specific Tsc1 (L-Tsc1 KO) knockout mice. L-Tsc1 KO mice displayed reduced locomotor activity, body temperature, and hepatic triglyceride content in a rapamycin-sensitive manner. Ectopic activation of mTORC1 also caused depletion of hepatic and plasma glutamine, leading to peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α)-dependent fibroblast growth factor 21 (FGF21) expression in the liver. Injection of glutamine or knockdown of PGC-1α or FGF21 in the liver suppressed the behavioral and metabolic defects due to mTORC1 activation. Thus, mTORC1 in the liver controls whole-body physiology through PGC-1α and FGF21. Finally, mTORC1 signaling correlated with FGF21 expression in human liver tumors, suggesting that treatment of glutamine-addicted cancers with mTOR inhibitors might have beneficial effects at both the tumor and whole-body level.
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