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Abstract
Cells metabolize nutrients for biosynthetic and bioenergetic needs to fuel growth and proliferation. The uptake of nutrients from the environment and their intracellular metabolism is a highly controlled process that involves cross talk between growth signaling and metabolic pathways. Despite constant fluctuations in nutrient availability and environmental signals, normal cells restore metabolic homeostasis to maintain cellular functions and prevent disease. A central signaling molecule that integrates growth with metabolism is the mechanistic target of rapamycin (mTOR). mTOR is a protein kinase that responds to levels of nutrients and growth signals. mTOR forms two protein complexes, mTORC1, which is sensitive to rapamycin, and mTORC2, which is not directly inhibited by this drug. Rapamycin has facilitated the discovery of the various functions of mTORC1 in metabolism. Genetic models that disrupt either mTORC1 or mTORC2 have expanded our knowledge of their cellular, tissue, as well as systemic functions in metabolism. Nevertheless, our knowledge of the regulation and functions of mTORC2, particularly in metabolism, has lagged behind. Since mTOR is an important target for cancer, aging, and other metabolism-related pathologies, understanding the distinct and overlapping regulation and functions of the two mTOR complexes is vital for the development of more effective therapeutic strategies. This review discusses the key discoveries and recent findings on the regulation and metabolic functions of the mTOR complexes. We highlight findings from cancer models but also discuss other examples of the mTOR-mediated metabolic reprogramming occurring in stem and immune cells, type 2 diabetes/obesity, neurodegenerative disorders, and aging.
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Affiliation(s)
- Angelia Szwed
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, New Jersey
| | - Eugene Kim
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, New Jersey
| | - Estela Jacinto
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, New Jersey
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Chawsheen MA, Dash PR. mTOR modulates resistance to gemcitabine in lung cancer in an MTORC2 dependent mechanism. Cell Signal 2021; 81:109934. [PMID: 33545231 DOI: 10.1016/j.cellsig.2021.109934] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2020] [Revised: 01/28/2021] [Accepted: 01/28/2021] [Indexed: 10/22/2022]
Abstract
BACKGROUND Lung cancer has a poor prognosis partly due to a lack of response to treatments such as the chemotherapy drug gemcitabine. Combinations of chemotherapy drugs with signal transduction inhibitors may be more effective treatments. In this study we have investigated the impact of targeting the mTOR signalling pathway on the efficacy of gemcitabine in different cancer cell lines. METHODS Time-lapse microscopy, immuno-staining, and western blot techniques were used to evaluate the efficacy of applied treatments either in measuring phosphorylation levels of mTOR down-stream targets or in tracking down the fate of targeted cells. Reactive oxygen species and relative levels of protein phosphorylation were also quantified. For comparison between treated groups t-test and analysis of variance test were applied. RESULTS Our data showed that mTORC1 has no role in sensitising A549 lung cancer cells to gemcitabine. However, targeting mTORC1/2 with the pharmacological inhibitor torin1 or by over-expressing Deptor, the negative regulator of mTOR signalling, sensitised these cells to gemcitabine. Silencing mTORC2, but not mTORC1, induced apoptosis and significantly improved the apoptosis-inducing effects of gemcitabine. Results also suggest that Rictor is required to maintain cell survival through modulating p38α, ERK1/2, RSK1/2/3 and the transcription factor STAT3. Multiple cell line comparisons revealed that PANC-1 pancreatic cancer cells were also sensitive to mTOR inhibition, but MCF7 breast cancer, MCF10A breast epithelial and H727 lung cancer cell lines were more resistant to the treatment. CONCLUSIONS Inhibition of mTORC2 may have benefits in the treatment of gemcitabine resistant cancers, and the genetic background of the cell line may determine its response to mTOR inhibition.
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Affiliation(s)
| | - Philip R Dash
- University of Reading, School of Biological Sciences, Reading, UK
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53
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Ye C, Liu B, Lu H, Liu J, Rabson AB, Jacinto E, Pestov DG, Shen Z. BCCIP is required for nucleolar recruitment of eIF6 and 12S pre-rRNA production during 60S ribosome biogenesis. Nucleic Acids Res 2021; 48:12817-12832. [PMID: 33245766 PMCID: PMC7736804 DOI: 10.1093/nar/gkaa1114] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 10/28/2020] [Accepted: 11/05/2020] [Indexed: 01/25/2023] Open
Abstract
Ribosome biogenesis is a fundamental process required for cell proliferation. Although evolutionally conserved, the mammalian ribosome assembly system is more complex than in yeasts. BCCIP was originally identified as a BRCA2 and p21 interacting protein. A partial loss of BCCIP function was sufficient to trigger genomic instability and tumorigenesis. However, a complete deletion of BCCIP arrested cell growth and was lethal in mice. Here, we report that a fraction of mammalian BCCIP localizes in the nucleolus and regulates 60S ribosome biogenesis. Both abrogation of BCCIP nucleolar localization and impaired BCCIP-eIF6 interaction can compromise eIF6 recruitment to the nucleolus and 60S ribosome biogenesis. BCCIP is vital for a pre-rRNA processing step that produces 12S pre-rRNA, a precursor to the 5.8S rRNA. However, a heterozygous Bccip loss was insufficient to impair 60S biogenesis in mouse embryo fibroblasts, but a profound reduction of BCCIP was required to abrogate its function in 60S biogenesis. These results suggest that BCCIP is a critical factor for mammalian pre-rRNA processing and 60S generation and offer an explanation as to why a subtle dysfunction of BCCIP can be tumorigenic but a complete depletion of BCCIP is lethal.
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Affiliation(s)
- Caiyong Ye
- Rutgers Cancer Institute of New Jersey, Department of Radiation Oncology, Rutgers Robert Wood Johnson Medical School, 195 Little Albany Street, New Brunswick, NJ 08901, USA
| | - Bochao Liu
- Rutgers Cancer Institute of New Jersey, Department of Radiation Oncology, Rutgers Robert Wood Johnson Medical School, 195 Little Albany Street, New Brunswick, NJ 08901, USA
| | - Huimei Lu
- Rutgers Cancer Institute of New Jersey, Department of Radiation Oncology, Rutgers Robert Wood Johnson Medical School, 195 Little Albany Street, New Brunswick, NJ 08901, USA
| | - Jingmei Liu
- Rutgers Cancer Institute of New Jersey, Department of Radiation Oncology, Rutgers Robert Wood Johnson Medical School, 195 Little Albany Street, New Brunswick, NJ 08901, USA
| | - Arnold B Rabson
- Department of Pharmacology, and The Child Health Institute of New Jersey, Rutgers Robert Wood Johnson Medical School, New Brunswick, NJ, USA
| | - Estela Jacinto
- Department of Biochemistry and Molecular Biology, Rutgers Robert Wood Johnson Medical School, Piscataway, NJ, USA
| | - Dimitri G Pestov
- Department of Cell Biology and Neuroscience, Rowan University School of Osteopathic Medicine, Stratford, NJ, USA
| | - Zhiyuan Shen
- Rutgers Cancer Institute of New Jersey, Department of Radiation Oncology, Rutgers Robert Wood Johnson Medical School, 195 Little Albany Street, New Brunswick, NJ 08901, USA
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54
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Smith EM, Benbahouche N, Morris K, Wilczynska A, Gillen S, Schmidt T, Meijer H, Jukes-Jones R, Cain K, Jones C, Stoneley M, Waldron J, Bell C, Fonseca B, Blagden S, Willis A, Bushell M. The mTOR regulated RNA-binding protein LARP1 requires PABPC1 for guided mRNA interaction. Nucleic Acids Res 2021; 49:458-478. [PMID: 33332560 PMCID: PMC7797073 DOI: 10.1093/nar/gkaa1189] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 11/16/2020] [Accepted: 12/11/2020] [Indexed: 12/16/2022] Open
Abstract
The mammalian target of rapamycin (mTOR) is a critical regulator of cell growth, integrating multiple signalling cues and pathways. Key among the downstream activities of mTOR is the control of the protein synthesis machinery. This is achieved, in part, via the co-ordinated regulation of mRNAs that contain a terminal oligopyrimidine tract (TOP) at their 5'ends, although the mechanisms by which this occurs downstream of mTOR signalling are still unclear. We used RNA-binding protein (RBP) capture to identify changes in the protein-RNA interaction landscape following mTOR inhibition. Upon mTOR inhibition, the binding of LARP1 to a number of mRNAs, including TOP-containing mRNAs, increased. Importantly, non-TOP-containing mRNAs bound by LARP1 are in a translationally-repressed state, even under control conditions. The mRNA interactome of the LARP1-associated protein PABPC1 was found to have a high degree of overlap with that of LARP1 and our data show that PABPC1 is required for the association of LARP1 with its specific mRNA targets. Finally, we demonstrate that mRNAs, including those encoding proteins critical for cell growth and survival, are translationally repressed when bound by both LARP1 and PABPC1.
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Affiliation(s)
- Ewan M Smith
- Cancer Research UK Beatson Institute, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, UK
| | - Nour El Houda Benbahouche
- Cancer Research UK Beatson Institute, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, UK
| | - Katherine Morris
- MRC Toxicology Unit, University of Cambridge, Leicester LE1 9HN, UK
| | - Ania Wilczynska
- Cancer Research UK Beatson Institute, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, UK
- Institute of Cancer Sciences, University of Glasgow, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1QH, UK
| | - Sarah Gillen
- Cancer Research UK Beatson Institute, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, UK
| | - Tobias Schmidt
- Cancer Research UK Beatson Institute, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, UK
| | - Hedda A Meijer
- Division of Cell and Developmental Biology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | | | - Kelvin Cain
- MRC Toxicology Unit, University of Cambridge, Leicester LE1 9HN, UK
| | - Carolyn Jones
- MRC Toxicology Unit, University of Cambridge, Leicester LE1 9HN, UK
| | - Mark Stoneley
- MRC Toxicology Unit, University of Cambridge, Leicester LE1 9HN, UK
| | - Joseph A Waldron
- Cancer Research UK Beatson Institute, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, UK
| | - Cameron Bell
- Cancer Research UK Therapeutic Discovery Laboratories, London Bioscience Innovation Centre, 2 Royal College Street, London NW1 0NH, UK
| | | | - Sarah Blagden
- Department of Oncology, University of Oxford, Oxford, OX3 7LE, UK
| | - Anne E Willis
- MRC Toxicology Unit, University of Cambridge, Leicester LE1 9HN, UK
| | - Martin Bushell
- Cancer Research UK Beatson Institute, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1BD, UK
- Institute of Cancer Sciences, University of Glasgow, Garscube Estate, Switchback Road, Bearsden, Glasgow G61 1QH, UK
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55
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Lin S, Zhao XL, Wang Z. TANK-binding kinase 1 mediates osteoclast differentiation by regulating NF-κB, MAPK and Akt signaling pathways. Immunol Cell Biol 2020; 99:223-233. [PMID: 32896936 DOI: 10.1111/imcb.12401] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2019] [Revised: 12/02/2019] [Accepted: 09/06/2020] [Indexed: 12/16/2022]
Abstract
TANK-binding kinase 1 (TBK1) belongs to the noncanonical IκB kinase (IKK) family. The ubiquitously expressed protein is well known to play a pivotal role in innate immune response and inflammation. Although excessive inflammatory activities have been shown to affect osteoclast (OC) differentiation and function, direct relevance of TBK1 in bone turnover is not known. In this work, we specifically altered the TBK1 protein level by knocking down or overexpressing it without affecting its homologous protein IKKε expression, and demonstrated the effect of TBK1 on OC differentiation in bone marrow macrophages (BMMs) and RAW264.7 cells upon induction by receptor activator of nuclear factor-κB (NF-κB) ligand (RANKL). TBK1 knockdown was found to markedly inhibit the OC differentiation and function, while TBK1 overexpression enhanced OC formation. Downregulation of TBK1 greatly suppressed RANKL-induced gene expression of Mmp9, Atp6v0d2, Acp5, Ctsk andNfatc1 involved in the regulation of OC formation and function in both BMM and RAW264.7 cells. Mechanistic studies indicated that TBK1 affected the NF-κB signaling pathway as well as mitogen-activated protein kinases (MAPKs) and protein kinase B (Akt) activation during OC differentiation. Moreover, the protein level of TNF receptor-associated factor 6 (TRAF6) was increased, and the interaction of TRAF6 with TBK1 was potentiated, by RANKL. Collectively, we provide direct evidence showing that TBK1 effectively mediates OC differentiation and function by regulating NF-κB, MAPKs and Akt signals. A TBK1-targeted therapeutic strategy may be useful for the treatment of bone-related disorders.
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Affiliation(s)
- Shuai Lin
- Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Xiao-Li Zhao
- Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Zhen Wang
- Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
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56
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Abstract
The Ras oncogene is notoriously difficult to target with specific therapeutics. Consequently, there is interest to better understand the Ras signaling pathways to identify potential targetable effectors. Recently, the mechanistic target of rapamycin complex 2 (mTORC2) was identified as an evolutionarily conserved Ras effector. mTORC2 regulates essential cellular processes, including metabolism, survival, growth, proliferation and migration. Moreover, increasing evidence implicate mTORC2 in oncogenesis. Little is known about the regulation of mTORC2 activity, but proposed mechanisms include a role for phosphatidylinositol (3,4,5)-trisphosphate - which is produced by class I phosphatidylinositol 3-kinases (PI3Ks), well-characterized Ras effectors. Therefore, the relationship between Ras, PI3K and mTORC2, in both normal physiology and cancer is unclear; moreover, seemingly conflicting observations have been reported. Here, we review the evidence on potential links between Ras, PI3K and mTORC2. Interestingly, data suggest that Ras and PI3K are both direct regulators of mTORC2 but that they act on distinct pools of mTORC2: Ras activates mTORC2 at the plasma membrane, whereas PI3K activates mTORC2 at intracellular compartments. Consequently, we propose a model to explain how Ras and PI3K can differentially regulate mTORC2, and highlight the diversity in the mechanisms of mTORC2 regulation, which appear to be determined by the stimulus, cell type, and the molecularly and spatially distinct mTORC2 pools.
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57
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Xu W, Hua H, Chiu YH, Li G, Zhi H, Yu Z, Ren F, Luo Y, Cui W. CD146 Regulates Growth Factor-Induced mTORC2 Activity Independent of the PI3K and mTORC1 Pathways. Cell Rep 2020; 29:1311-1322.e5. [PMID: 31665642 DOI: 10.1016/j.celrep.2019.09.047] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2019] [Revised: 08/09/2019] [Accepted: 09/17/2019] [Indexed: 12/21/2022] Open
Abstract
The mechanistic target of rapamycin complex 2 (mTORC2) coordinates cell proliferation, survival, and metabolism with environmental inputs, yet how extracellular stimuli such as growth factors (GFs) activate mTORC2 remains enigmatic. Here we demonstrate that in human endothelial cells, activation of mTORC2 signaling by GFs is mediated by transmembrane cell adhesion protein CD146. Upon GF stimulation, the cytoplasmic tail of CD146 is phosphorylated, which permits its positively charged, juxtamembrane KKGK motif to interact with Rictor, the defining subunit of mTORC2. The formation of the CD146-Rictor/mTORC2 complex protects Rictor from ubiquitin-proteasome-mediated degradation, thereby specifically upregulating mTORC2 activity with no intervention of the PI3K and mTORC1 pathways. This CD146-mediated mTORC2 activation in response to GF stimulation promotes cell proliferation and survival. Therefore, our findings identify a molecular mechanism by which extracellular stimuli regulate mTORC2 activity, linking environmental cues with mTORC2 regulation.
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Affiliation(s)
- Wenyi Xu
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, China Agricultural University, Beijing 100193, China; College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China
| | - Huijuan Hua
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, China Agricultural University, Beijing 100193, China; College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Yueh-Ho Chiu
- Institute of Reproductive and Developmental Biology, Faculty of Medicine, Imperial College London, Du Cane Road, London W12 0NN, UK
| | - Guannan Li
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, China Agricultural University, Beijing 100193, China; College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China
| | - Huihan Zhi
- Institute of Reproductive and Developmental Biology, Faculty of Medicine, Imperial College London, Du Cane Road, London W12 0NN, UK
| | - Zhengquan Yu
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, China Agricultural University, Beijing 100193, China; College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Fazheng Ren
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, China Agricultural University, Beijing 100193, China; College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China
| | - Yongting Luo
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, China Agricultural University, Beijing 100193, China.
| | - Wei Cui
- Institute of Reproductive and Developmental Biology, Faculty of Medicine, Imperial College London, Du Cane Road, London W12 0NN, UK.
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58
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Song X, Cai H, Yang C, Xue X, Wang J, Mo Y, Zhu M, Zhu G, Ye L, Jin M. Possible Novel Therapeutic Targets in Lymphangioleiomyomatosis Treatment. Front Med (Lausanne) 2020; 7:554134. [PMID: 33072782 PMCID: PMC7542236 DOI: 10.3389/fmed.2020.554134] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Accepted: 08/13/2020] [Indexed: 12/16/2022] Open
Abstract
Lymphangioleiomyomatosis (LAM) is a rare systemic neoplastic disease that exclusively happens in women. Studies focusing on LAM and tuberous sclerosis complex (TSC) have made great progress in understanding the pathogenesis and searching for treatment. The inactive mutation of TSC1 or TSC2 is found in patients with LAM to activate the crucial mammalian target of rapamycin (mTOR) signaling pathway and result in enhanced cell proliferation and migration. However, it does not explain every step of tumorigenesis in LAM. Because cessation of rapamycin would break the stabilization of lung function or improved quality of life and lead to disease recurrent, continued studies on the pathogenesis of LAM are necessary to identify novel targets and new treatment. Researchers have found several aberrant regulations that affect the mTOR pathway such as its upstream or downstream molecules and compensatory pathways in LAM. Some therapeutic targets have been under study in clinical trials. New methods like genome-wide association studies have located a novel gene related to LAM. Herein, we review the current knowledge regarding pathogenesis and treatment of LAM and summarize novel targets of therapeutic potential recently.
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Affiliation(s)
- Xixi Song
- Department of Pulmonary and Critical Care Medicine, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Hui Cai
- Department of Pulmonary and Critical Care Medicine, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Chengyu Yang
- Department of Pulmonary and Critical Care Medicine, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Xiaomin Xue
- Department of Pulmonary and Critical Care Medicine, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Jian Wang
- Department of Pulmonary and Critical Care Medicine, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Yuqing Mo
- Department of Pulmonary and Critical Care Medicine, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Mengchan Zhu
- Department of Pulmonary and Critical Care Medicine, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Guiping Zhu
- Department of Pulmonary and Critical Care Medicine, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Ling Ye
- Department of Pulmonary and Critical Care Medicine, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Meiling Jin
- Department of Pulmonary and Critical Care Medicine, Zhongshan Hospital, Fudan University, Shanghai, China
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59
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Fu W, Hall MN. Regulation of mTORC2 Signaling. Genes (Basel) 2020; 11:E1045. [PMID: 32899613 PMCID: PMC7564249 DOI: 10.3390/genes11091045] [Citation(s) in RCA: 112] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2020] [Revised: 08/31/2020] [Accepted: 09/02/2020] [Indexed: 12/12/2022] Open
Abstract
Mammalian target of rapamycin (mTOR), a serine/threonine protein kinase and a master regulator of cell growth and metabolism, forms two structurally and functionally distinct complexes, mTOR complex 1 (mTORC1) and mTORC2. While mTORC1 signaling is well characterized, mTORC2 is relatively poorly understood. mTORC2 appears to exist in functionally distinct pools, but few mTORC2 effectors/substrates have been identified. Here, we review recent advances in our understanding of mTORC2 signaling, with particular emphasis on factors that control mTORC2 activity.
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Affiliation(s)
- Wenxiang Fu
- Center for Life Sciences, School of Life Sciences, Yunnan University, Kunming 650500, China
- Biozentrum, University of Basel, CH4056 Basel, Switzerland;
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60
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Takahara T, Amemiya Y, Sugiyama R, Maki M, Shibata H. Amino acid-dependent control of mTORC1 signaling: a variety of regulatory modes. J Biomed Sci 2020; 27:87. [PMID: 32799865 PMCID: PMC7429791 DOI: 10.1186/s12929-020-00679-2] [Citation(s) in RCA: 130] [Impact Index Per Article: 32.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 07/30/2020] [Indexed: 01/10/2023] Open
Abstract
The mechanistic target of rapamycin complex 1 (mTORC1) is an essential regulator of cell growth and metabolism through the modulation of protein and lipid synthesis, lysosome biogenesis, and autophagy. The activity of mTORC1 is dynamically regulated by several environmental cues, including amino acid availability, growth factors, energy levels, and stresses, to coordinate cellular status with environmental conditions. Dysregulation of mTORC1 activity is closely associated with various diseases, including diabetes, cancer, and neurodegenerative disorders. The discovery of Rag GTPases has greatly expanded our understanding of the regulation of mTORC1 activity by amino acids, especially leucine and arginine. In addition to Rag GTPases, other factors that also contribute to the modulation of mTORC1 activity have been identified. In this review, we discuss the mechanisms of regulation of mTORC1 activity by particular amino acids.
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Affiliation(s)
- Terunao Takahara
- Department of Applied Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, 464-8601, Japan.
| | - Yuna Amemiya
- Department of Applied Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, 464-8601, Japan
| | - Risa Sugiyama
- Department of Applied Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, 464-8601, Japan
| | - Masatoshi Maki
- Department of Applied Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, 464-8601, Japan
| | - Hideki Shibata
- Department of Applied Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, 464-8601, Japan
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61
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TMBIM6/BI-1 contributes to cancer progression through assembly with mTORC2 and AKT activation. Nat Commun 2020; 11:4012. [PMID: 32782388 PMCID: PMC7419509 DOI: 10.1038/s41467-020-17802-4] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Accepted: 07/16/2020] [Indexed: 01/09/2023] Open
Abstract
Transmembrane B cell lymphoma 2-associated X protein inhibitor motif-containing (TMBIM) 6, a Ca2+ channel-like protein, is highly up-regulated in several cancer types. Here, we show that TMBIM6 is closely associated with survival in patients with cervical, breast, lung, and prostate cancer. TMBIM6 deletion or knockdown suppresses primary tumor growth. Further, mTORC2 activation is up-regulated by TMBIM6 and stimulates glycolysis, protein synthesis, and the expression of lipid synthesis genes and glycosylated proteins. Moreover, ER-leaky Ca2+ from TMBIM6, a unique characteristic, is shown to affect mTORC2 assembly and its association with ribosomes. In addition, we identify that the BIA compound, a potentialTMBIM6 antagonist, prevents TMBIM6 binding to mTORC2, decreases mTORC2 activity, and also regulates TMBIM6-leaky Ca2+, further suppressing tumor formation and progression in cancer xenograft models. This previously unknown signaling cascade in which mTORC2 activity is enhanced via the interaction with TMBIM6 provides potential therapeutic targets for various malignancies. TMBIM6, a member of the transmembrane BI-1 motif-containing family of proteins, is overexpressed in many cancer types. Here, the authors show that TMBIM6 regulates AKT activation through mTORC2 assembly and ribosome association and identify an antagonist of TMBIM6 with anti-tumor properties.
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62
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Chou PC, Rajput S, Zhao X, Patel C, Albaciete D, Oh WJ, Daguplo HQ, Patel N, Su B, Werlen G, Jacinto E. mTORC2 Is Involved in the Induction of RSK Phosphorylation by Serum or Nutrient Starvation. Cells 2020; 9:E1567. [PMID: 32605013 PMCID: PMC7408474 DOI: 10.3390/cells9071567] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2020] [Revised: 06/17/2020] [Accepted: 06/23/2020] [Indexed: 12/26/2022] Open
Abstract
Cells adjust to nutrient fluctuations to restore metabolic homeostasis. The mechanistic target of rapamycin (mTOR) complex 2 responds to nutrient levels and growth signals to phosphorylate protein kinases belonging to the AGC (Protein Kinases A,G,C) family such as Akt and PKC. Phosphorylation of these AGC kinases at their conserved hydrophobic motif (HM) site by mTORC2 enhances their activation and mediates the functions of mTORC2 in cell growth and metabolism. Another AGC kinase family member that is known to undergo increased phosphorylation at the homologous HM site (Ser380) is the p90 ribosomal S6 kinase (RSK). Phosphorylation at Ser380 is facilitated by the activation of the mitogen-activated protein kinase/extracellular signal regulated kinase (MAPK/ERK) in response to growth factor stimulation. Here, we demonstrate that optimal phosphorylation of RSK at this site requires an intact mTORC2. We also found that RSK is robustly phosphorylated at Ser380 upon nutrient withdrawal or inhibition of glycolysis, conditions that increase mTORC2 activation. However, pharmacological inhibition of mTOR did not abolish RSK phosphorylation at Ser380, indicating that mTOR catalytic activity is not required for this phosphorylation. Since RSK and SIN1β colocalize at the membrane during serum restimulation and acute glutamine withdrawal, mTORC2 could act as a scaffold to enhance RSK HM site phosphorylation. Among the known RSK substrates, the CCTβ subunit of the chaperonin containing TCP-1 (CCT) complex had defective phosphorylation in the absence of mTORC2. Our findings indicate that the mTORC2-mediated phosphorylation of the RSK HM site could confer RSK substrate specificity and reveal that RSK responds to nutrient fluctuations.
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Affiliation(s)
- Po-Chien Chou
- Department of Biochemistry and Molecular Biology, Rutgers-Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA; (P.-C.C.); (S.R.); (C.P.); (D.A.); (W.J.O.); (H.Q.D.); (N.P.); (G.W.)
| | - Swati Rajput
- Department of Biochemistry and Molecular Biology, Rutgers-Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA; (P.-C.C.); (S.R.); (C.P.); (D.A.); (W.J.O.); (H.Q.D.); (N.P.); (G.W.)
| | - Xiaoyun Zhao
- Department of Immunology and Microbiology, Shanghai Jiao Tong University School of Medicine, Shanghai 200240, China; (X.Z.); (B.S.)
| | - Chadni Patel
- Department of Biochemistry and Molecular Biology, Rutgers-Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA; (P.-C.C.); (S.R.); (C.P.); (D.A.); (W.J.O.); (H.Q.D.); (N.P.); (G.W.)
| | - Danielle Albaciete
- Department of Biochemistry and Molecular Biology, Rutgers-Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA; (P.-C.C.); (S.R.); (C.P.); (D.A.); (W.J.O.); (H.Q.D.); (N.P.); (G.W.)
| | - Won Jun Oh
- Department of Biochemistry and Molecular Biology, Rutgers-Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA; (P.-C.C.); (S.R.); (C.P.); (D.A.); (W.J.O.); (H.Q.D.); (N.P.); (G.W.)
| | - Heineken Queen Daguplo
- Department of Biochemistry and Molecular Biology, Rutgers-Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA; (P.-C.C.); (S.R.); (C.P.); (D.A.); (W.J.O.); (H.Q.D.); (N.P.); (G.W.)
| | - Nikhil Patel
- Department of Biochemistry and Molecular Biology, Rutgers-Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA; (P.-C.C.); (S.R.); (C.P.); (D.A.); (W.J.O.); (H.Q.D.); (N.P.); (G.W.)
| | - Bing Su
- Department of Immunology and Microbiology, Shanghai Jiao Tong University School of Medicine, Shanghai 200240, China; (X.Z.); (B.S.)
| | - Guy Werlen
- Department of Biochemistry and Molecular Biology, Rutgers-Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA; (P.-C.C.); (S.R.); (C.P.); (D.A.); (W.J.O.); (H.Q.D.); (N.P.); (G.W.)
| | - Estela Jacinto
- Department of Biochemistry and Molecular Biology, Rutgers-Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA; (P.-C.C.); (S.R.); (C.P.); (D.A.); (W.J.O.); (H.Q.D.); (N.P.); (G.W.)
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Laribee RN, Weisman R. Nuclear Functions of TOR: Impact on Transcription and the Epigenome. Genes (Basel) 2020; 11:E641. [PMID: 32532005 PMCID: PMC7349558 DOI: 10.3390/genes11060641] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 06/04/2020] [Accepted: 06/09/2020] [Indexed: 12/15/2022] Open
Abstract
The target of rapamycin (TOR) protein kinase is at the core of growth factor- and nutrient-dependent signaling pathways that are well-known for their regulation of metabolism, growth, and proliferation. However, TOR is also involved in the regulation of gene expression, genomic and epigenomic stability. TOR affects nuclear functions indirectly through its activity in the cytoplasm, but also directly through active nuclear TOR pools. The mechanisms by which TOR regulates its nuclear functions are less well-understood compared with its cytoplasmic activities. TOR is an important pharmacological target for several diseases, including cancer, metabolic and neurological disorders. Thus, studies of the nuclear functions of TOR are important for our understanding of basic biological processes, as well as for clinical implications.
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Affiliation(s)
- R. Nicholas Laribee
- Department of Pathology and Laboratory Medicine, College of Medicine and Center for Cancer Research, University of Tennessee Health Science Center, 19 South Manassas, Cancer Research Building Rm 318, Memphis, TN 38163, USA
| | - Ronit Weisman
- Department of Natural and Life Sciences, The Open University of Israel, University Road 1, Ra’anana 4353701, Israel
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64
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Yudushkin I. Control of Akt activity and substrate phosphorylation in cells. IUBMB Life 2020; 72:1115-1125. [PMID: 32125765 PMCID: PMC7317883 DOI: 10.1002/iub.2264] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2019] [Accepted: 02/22/2020] [Indexed: 12/20/2022]
Abstract
Protein kinase B/Akt is a serine/threonine kinase that links receptors coupled to the PI3K lipid kinase to cellular anabolic pathways. Its activity in cells is controlled by reversible phosphorylation and an intramolecular lipid-controlled allosteric switch. In this review, I outline the current progress in understanding Akt regulatory mechanisms, define three models of Akt activation in cells, and highlight how intramolecular allosterism cooperates with cell-autonomous mechanisms to control Akt localization and activity and direct it toward specific sets of substrates in cells.
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Affiliation(s)
- Ivan Yudushkin
- Department of Structural and Computational BiologyUniversity of ViennaViennaAustria
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65
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Nagai MH, Xavier VPS, Gutiyama LM, Machado CF, Reis AH, Donnard ER, Galante PAF, Abreu JG, Festuccia WT, Malnic B. Depletion of Ric-8B leads to reduced mTORC2 activity. PLoS Genet 2020; 16:e1008255. [PMID: 32392211 PMCID: PMC7252638 DOI: 10.1371/journal.pgen.1008255] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Revised: 05/27/2020] [Accepted: 02/24/2020] [Indexed: 11/19/2022] Open
Abstract
mTOR, a serine/threonine protein kinase that is involved in a series of critical cellular processes, can be found in two functionally distinct complexes, mTORC1 and mTORC2. In contrast to mTORC1, little is known about the mechanisms that regulate mTORC2. Here we show that mTORC2 activity is reduced in mice with a hypomorphic mutation of the Ric-8B gene. Ric-8B is a highly conserved protein that acts as a non-canonical guanine nucleotide exchange factor (GEF) for heterotrimeric Gαs/olf type subunits. We found that Ric-8B hypomorph embryos are smaller than their wild type littermates, fail to close the neural tube in the cephalic region and die during mid-embryogenesis. Comparative transcriptome analysis revealed that signaling pathways involving GPCRs and G proteins are dysregulated in the Ric-8B mutant embryos. Interestingly, this analysis also revealed an unexpected impairment of the mTOR signaling pathway. Phosphorylation of Akt at Ser473 is downregulated in the Ric-8B mutant embryos, indicating a decreased activity of mTORC2. Knockdown of the endogenous Ric-8B gene in cultured cell lines leads to reduced phosphorylation levels of Akt (Ser473), further supporting the involvement of Ric-8B in mTORC2 activity. Our results reveal a crucial role for Ric-8B in development and provide novel insights into the signals that regulate mTORC2. Gene inactivation in mice can be used to identify genes that are involved in important biological processes and that may contribute to disease. We used this approach to study the Ric-8B gene, which is highly conserved in mammals, including humans. We found that Ric-8B is essential for embryogenesis and for the proper development of the nervous system. Ric-8B mutant mouse embryos are smaller than their wild type littermates and show neural tube defects at the cranial region. This approach also allowed us to identify the biological pathways that potentially contribute to the observed phenotypes, and uncover a novel role for Ric-8B in the mTORC2 signaling pathway. mTORC2 plays particular important roles in the adult brain, and has been implicated in neurological disorders. Our mutant mice provide a model to study the complex molecular and cellular processes underlying the interplay between Ric-8B and mTORC2 in neuronal function.
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Affiliation(s)
- Maíra H. Nagai
- Department of Biochemistry, University of São Paulo, São Paulo, Brazil
| | | | | | | | - Alice H. Reis
- Institute of Biomedical Sciences, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Elisa R. Donnard
- Centro de Oncologia Molecular, Hospital Sírio-Libanês, São Paulo, Brazil
| | | | - Jose G. Abreu
- Institute of Biomedical Sciences, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - William T. Festuccia
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Bettina Malnic
- Department of Biochemistry, University of São Paulo, São Paulo, Brazil
- * E-mail:
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66
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Helmy MW, Ghoneim AI, Katary MA, Elmahdy RK. The synergistic anti-proliferative effect of the combination of diosmin and BEZ-235 (dactolisib) on the HCT-116 colorectal cancer cell line occurs through inhibition of the PI3K/Akt/mTOR/NF-κB axis. Mol Biol Rep 2020; 47:2217-2230. [DOI: 10.1007/s11033-020-05327-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Accepted: 02/13/2020] [Indexed: 12/11/2022]
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Wang W, He S, Zhang R, Peng J, Guo D, Zhang J, Xiang B, Li L. ALDH1A1 maintains the cancer stem-like cells properties of esophageal squamous cell carcinoma by activating the AKT signal pathway and interacting with β-catenin. Biomed Pharmacother 2020; 125:109940. [PMID: 32044720 DOI: 10.1016/j.biopha.2020.109940] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 01/17/2020] [Accepted: 01/23/2020] [Indexed: 12/28/2022] Open
Abstract
Aldehyde dehydrogenase 1A1 (ALDH1A1) is a marker of cancer stem-like cells (CSCs), but knowledge about the molecular mechanism of ALDH1A1 in maintaining the properties of CSCs remains limited. ALDH1A1 immunohistochemistry was performed in esophageal squamous cell carcinoma (ESCC) tissues, Western blotting was used to detect relationship between ALDH1A1 and AKT or β-catenin. Subcutaneous transplantation of tumors and drug resistance, spherogenesis experiments were used to test the ESCC cell stemness. Co-IP and confocal were used to detected the co-localization of LADH1A1 and β-catenin. ALDH1A1 expression maintained the CSC properties of ESCC cells. It enhanced the chemo-resistance ability, clonogenicity, and spherogenesis in vitro and tumorigenicity in vivo. High ALDH1A1 expression is an adverse prognostic factor of ESCC patients. Small-molecule inhibitor NCT-501 down-regulates ALDH1A1 expression and inhibits the AKT-β-catenin signaling pathway. ALDH1A1 overexpression activates the AKT signaling pathway. ALDH1A1 interacts with β-catenin, co-localization in KYS-510 cells.
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Affiliation(s)
- Wei Wang
- Department of Pathology, Affiliated Hospital of Jining Medical University, Jining Medical University, Jining, Shandong 272029, China.
| | - Shujin He
- Department of Pathology, Affiliated Hospital of Jining Medical University, Jining Medical University, Jining, Shandong 272029, China
| | - Renya Zhang
- Department of Pathology, Affiliated Hospital of Jining Medical University, Jining Medical University, Jining, Shandong 272029, China
| | - Jie Peng
- Department of Pathology, Affiliated Hospital of Jining Medical University, Jining Medical University, Jining, Shandong 272029, China
| | - Daolu Guo
- Department of Pathology, Affiliated Hospital of Jining Medical University, Jining Medical University, Jining, Shandong 272029, China
| | - Jinguo Zhang
- Department of Cardiology, Affiliated Hospital of Jining Medical University, Jining Medical University, Jining, Shandong 272029, China
| | - Bo Xiang
- The Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute and School of Basic Medical Sciences, Central South University, Changsha, 410078, Hunan, China
| | - Lei Li
- Department of Pathology, Affiliated Hospital of Jining Medical University, Jining Medical University, Jining, Shandong 272029, China
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68
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Akkoc Y, Gozuacik D. MicroRNAs as major regulators of the autophagy pathway. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2020; 1867:118662. [PMID: 32001304 DOI: 10.1016/j.bbamcr.2020.118662] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Revised: 01/13/2020] [Accepted: 01/23/2020] [Indexed: 01/17/2023]
Abstract
Autophagy is a cellular stress response mechanism activation of which leads to degradation of cellular components, including proteins as well as damaged organelles in lysosomes. Defects in autophagy mechanisms were associated with several pathologies (e.g. cancer, neurodegenerative diseases, and rare genetic diseases). Therefore, autophagy regulation is under strict control. Transcriptional and post-translational mechanisms that control autophagy in cells and organisms studied in detail. Recent studies introduced non-coding small RNAs, and especially microRNAs (miRNAs) in the post-translational orchestration of the autophagic activity. In this review article, we analyzed in detail the current status of autophagy-miRNA connections. Comprehensive documentation of miRNAs that were directly involved in autophagy regulation resulted in the emergence of common themes and concepts governing these complex and intricate interactions. Hence, a better and systematic understanding of these interactions reveals a central role for miRNAs in the regulation of autophagy.
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Affiliation(s)
- Yunus Akkoc
- Sabanci University, Faculty of Engineering and Natural Sciences, Molecular Biology, Genetics and Bioengineering Program, Orhanli-Tuzla 34956, Istanbul, Turkey
| | - Devrim Gozuacik
- Sabanci University, Faculty of Engineering and Natural Sciences, Molecular Biology, Genetics and Bioengineering Program, Orhanli-Tuzla 34956, Istanbul, Turkey; Sabanci University Nanotechnology Research and Application Center, Sabanci University, Istanbul 34956, Turkey.
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69
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Knudsen JR, Fritzen AM, James DE, Jensen TE, Kleinert M, Richter EA. Growth Factor-Dependent and -Independent Activation of mTORC2. Trends Endocrinol Metab 2020; 31:13-24. [PMID: 31699566 DOI: 10.1016/j.tem.2019.09.005] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Revised: 08/19/2019] [Accepted: 09/12/2019] [Indexed: 01/03/2023]
Abstract
The target of rapamycin complex 2 (TORC2) was discovered in 2002 in budding yeast. Its mammalian counterpart, mTORC2, was first described in 2004. Soon thereafter it was demonstrated that mTORC2 directly phosphorylates Akt on Ser473, ending a long search for the elusive 'second' insulin-responsive Akt kinase. In this review we discuss key evidence pertaining to the subcellular localization of mTORC2, highlighting a spatial heterogeneity that relates to mTORC2 activation. We summarize current models for how growth factors (GFs), such as insulin, trigger mTORC2 activation, and we provide a comprehensive discussion focusing on a new exciting frontier, the molecular mechanisms underpinning GF-independent activation of mTORC2.
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Affiliation(s)
- Jonas R Knudsen
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Andreas M Fritzen
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - David E James
- School of Life and Environmental Sciences and Charles Perkins Centre, The University of Sydney, Sydney, NSW, Australia; Sydney Medical School, The University of Sydney, Sydney, NSW, Australia
| | - Thomas E Jensen
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Maximilian Kleinert
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark; Institute for Diabetes and Obesity, Helmholtz Diabetes Center (HDC), Helmholtz Zentrum Muenchen & German Center for Diabetes Research (DZD), Neuherberg, Germany.
| | - Erik A Richter
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark.
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70
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Lee HC, Zhao YJ. Resolving the topological enigma in Ca 2+ signaling by cyclic ADP-ribose and NAADP. J Biol Chem 2019; 294:19831-19843. [PMID: 31672920 PMCID: PMC6937575 DOI: 10.1074/jbc.rev119.009635] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cyclic ADP-ribose (cADPR) and nicotinic acid adenine dinucleotide phosphate (NAADP) are two structurally distinct messengers that mobilize the endoplasmic and endolysosomal Ca2+ stores, respectively. Both are synthesized by the CD38 molecule (CD38), which has long been thought to be a type II membrane protein whose catalytic domain, intriguingly, faces to the outside of the cell. Accordingly, for more than 20 years, it has remained unresolved how CD38 can use cytosolic substrates such as NAD and NADP to produce messengers that target intracellular Ca2+ stores. The discovery of type III CD38, whose catalytic domain faces the cytosol, has now begun to clarify this topological conundrum. This article reviews the ideas and clues leading to the discovery of the type III CD38; highlights an innovative approach for uncovering its natural existence; and discusses the regulators of its activity, folding, and degradation. We also review the compartmentalization of cADPR and NAADP biogenesis. We further discuss the possible mechanisms that promote type III CD38 expression and appraise a proposal of a Ca2+-signaling mechanism based on substrate limitation and product translocation. The surprising finding of another enzyme that produces cADPR and NAADP, sterile α and TIR motif-containing 1 (SARM1), is described. SARM1 regulates axonal degeneration and has no sequence similarity with CD38 but can catalyze the same set of multireactions and has the same cytosolic orientation as the type III CD38. The intriguing finding that SARM1 is activated by nicotinamide mononucleotide to produce cADPR and NAADP suggests that it may function as a regulated Ca2+-signaling enzyme like CD38.
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Affiliation(s)
- Hon Cheung Lee
- State Key Laboratory of Chemical Oncogenomics, Key Laboratory of Chemical Genomics, Peking University Shenzhen Graduate School, Shenzhen, China, 518055
| | - Yong Juan Zhao
- State Key Laboratory of Chemical Oncogenomics, Key Laboratory of Chemical Genomics, Peking University Shenzhen Graduate School, Shenzhen, China, 518055
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71
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Magaway C, Kim E, Jacinto E. Targeting mTOR and Metabolism in Cancer: Lessons and Innovations. Cells 2019; 8:cells8121584. [PMID: 31817676 PMCID: PMC6952948 DOI: 10.3390/cells8121584] [Citation(s) in RCA: 130] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 12/02/2019] [Accepted: 12/03/2019] [Indexed: 12/14/2022] Open
Abstract
Cancer cells support their growth and proliferation by reprogramming their metabolism in order to gain access to nutrients. Despite the heterogeneity in genetic mutations that lead to tumorigenesis, a common alteration in tumors occurs in pathways that upregulate nutrient acquisition. A central signaling pathway that controls metabolic processes is the mTOR pathway. The elucidation of the regulation and functions of mTOR can be traced to the discovery of the natural compound, rapamycin. Studies using rapamycin have unraveled the role of mTOR in the control of cell growth and metabolism. By sensing the intracellular nutrient status, mTOR orchestrates metabolic reprogramming by controlling nutrient uptake and flux through various metabolic pathways. The central role of mTOR in metabolic rewiring makes it a promising target for cancer therapy. Numerous clinical trials are ongoing to evaluate the efficacy of mTOR inhibition for cancer treatment. Rapamycin analogs have been approved to treat specific types of cancer. Since rapamycin does not fully inhibit mTOR activity, new compounds have been engineered to inhibit the catalytic activity of mTOR to more potently block its functions. Despite highly promising pre-clinical studies, early clinical trial results of these second generation mTOR inhibitors revealed increased toxicity and modest antitumor activity. The plasticity of metabolic processes and seemingly enormous capacity of malignant cells to salvage nutrients through various mechanisms make cancer therapy extremely challenging. Therefore, identifying metabolic vulnerabilities in different types of tumors would present opportunities for rational therapeutic strategies. Understanding how the different sources of nutrients are metabolized not just by the growing tumor but also by other cells from the microenvironment, in particular, immune cells, will also facilitate the design of more sophisticated and effective therapeutic regimen. In this review, we discuss the functions of mTOR in cancer metabolism that have been illuminated from pre-clinical studies. We then review key findings from clinical trials that target mTOR and the lessons we have learned from both pre-clinical and clinical studies that could provide insights on innovative therapeutic strategies, including immunotherapy to target mTOR signaling and the metabolic network in cancer.
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72
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Ruan C, Ouyang X, Liu H, Li S, Jin J, Tang W, Xia Y, Su B. Sin1-mediated mTOR signaling in cell growth, metabolism and immune response. Natl Sci Rev 2019; 6:1149-1162. [PMID: 34691993 PMCID: PMC8291397 DOI: 10.1093/nsr/nwz171] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Revised: 10/22/2019] [Accepted: 10/22/2019] [Indexed: 12/22/2022] Open
Abstract
Abstract
The mammalian target of rapamycin (mTOR) is an evolutionarily conserved Ser/Thr protein kinase with essential cellular function via processing various extracellular and intracellular inputs. Two distinct multi-protein mTOR complexes (mTORC), mTORC1 and mTORC2, have been identified and well characterized in eukaryotic cells from yeast to human. Sin1, which stands for Sty1/Spc1-interacting protein1, also known as mitogen-activated protein kinase (MAPK) associated protein (MAPKAP)1, is an evolutionarily conserved adaptor protein. Mammalian Sin1 interacts with many cellular proteins, but it has been widely studied as an essential component of mTORC2, and it is crucial not only for the assembly of mTORC2 but also for the regulation of its substrate specificity. In this review, we summarize our current knowledge of the structure and functions of Sin1, focusing specifically on its protein interaction network and its roles in the mTOR pathway that could account for various cellular functions of mTOR in growth, metabolism, immunity and cancer.
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Affiliation(s)
- Chun Ruan
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, and the Minister of Education Key Laboratory of Cell Death and Differentiation, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Xinxing Ouyang
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, and the Minister of Education Key Laboratory of Cell Death and Differentiation, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Hongzhi Liu
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, and the Minister of Education Key Laboratory of Cell Death and Differentiation, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Song Li
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, and the Minister of Education Key Laboratory of Cell Death and Differentiation, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Jingsi Jin
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, and the Minister of Education Key Laboratory of Cell Death and Differentiation, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Weiyi Tang
- Zhiyuan College, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Yu Xia
- Zhiyuan College, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Bing Su
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, and the Minister of Education Key Laboratory of Cell Death and Differentiation, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
- Zhiyuan College, Shanghai Jiao Tong University, Shanghai 200240, China
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73
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Colorectal cancer cells respond differentially to autophagy inhibition in vivo. Sci Rep 2019; 9:11316. [PMID: 31383875 PMCID: PMC6683171 DOI: 10.1038/s41598-019-47659-7] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Accepted: 07/19/2019] [Indexed: 12/19/2022] Open
Abstract
Autophagy has both tumor-promoting and -suppressing effects in cancer, including colorectal cancer (CRC), with transformed cells often exhibiting high autophagic flux. In established tumors, autophagy inhibition can lead to opposite responses resulting in either tumor cell death or hyperproliferation. The functional mechanisms underlying these differences are poorly understood. The present study aimed to investigate the relationship between the autophagic capacities of CRC cells and their sensitivities to autophagy inhibition. All studied CRC cell lines showed high basal autophagic flux. However, only HCT116 and Caco-2/15 cells displayed regulated autophagic flux upon starvation. Knockdown of ATG5 (which disrupts autophagosome elongation) or RAB21 (which decreases autophagosome/lysosome fusion) had little effect on CRC cell proliferation in vitro. Nonetheless, inhibition of autophagy in vivo had a substantial cell line-dependent impact on tumor growth, with some cells displaying decreased (HCT116 and Caco-2/15) or increased (SW480 and LoVo) proliferation. RNA sequencing and Western blot analyses in hyperproliferative SW480 tumors revealed that the mTORC2 and AKT pathways were hyperactivated following autophagy impairment. Inhibition of either mTOR or AKT activities rescued the observed hyperproliferation in autophagy-inhibited SW480 and reduced tumor growth. These results highlight that autophagy inhibition can lead, in specific cellular contexts, to compensatory mechanisms promoting tumor growth.
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74
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Chung CZ, Balasuriya N, Manni E, Liu X, Li SSC, O’Donoghue P, Heinemann IU. Gld2 activity is regulated by phosphorylation in the N-terminal domain. RNA Biol 2019; 16:1022-1033. [PMID: 31057087 PMCID: PMC6602411 DOI: 10.1080/15476286.2019.1608754] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Revised: 03/25/2019] [Accepted: 04/14/2019] [Indexed: 02/06/2023] Open
Abstract
The de-regulation of microRNAs (miRNAs) is associated with multiple human diseases, yet cellular mechanisms governing miRNA abundance remain largely elusive. Human miR-122 is required for Hepatitis C proliferation, and low miR-122 abundance is associated with hepatic cancer. The adenylyltransferase Gld2 catalyses the post-transcriptional addition of a single adenine residue (A + 1) to the 3'-end of miR-122, enhancing its stability. Gld2 activity is inhibited by binding to the Hepatitis C virus core protein during HepC infection, but no other mechanisms of Gld2 regulation are known. We found that Gld2 activity is regulated by site-specific phosphorylation in its disordered N-terminal domain. We identified two phosphorylation sites (S62, S110) where phosphomimetic substitutions increased Gld2 activity and one site (S116) that markedly reduced activity. Using mass spectrometry, we confirmed that HEK 293 cells readily phosphorylate the N-terminus of Gld2. We identified protein kinase A (PKA) and protein kinase B (Akt1) as the kinases that site-specifically phosphorylate Gld2 at S116, abolishing Gld2-mediated nucleotide addition. The data demonstrate a novel phosphorylation-dependent mechanism to regulate Gld2 activity, revealing tumour suppressor miRNAs as a previously unknown target of Akt1-dependent signalling.
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Affiliation(s)
- Christina Z. Chung
- Department of Biochemistry, The University of Western Ontario, London, Canada
| | - Nileeka Balasuriya
- Department of Biochemistry, The University of Western Ontario, London, Canada
| | - Emad Manni
- Department of Biochemistry, The University of Western Ontario, London, Canada
| | - Xuguang Liu
- Department of Biochemistry, The University of Western Ontario, London, Canada
| | - Shawn Shun-Cheng Li
- Department of Biochemistry, The University of Western Ontario, London, Canada
- Department of Oncology and Child Health Research Institute, The University of Western Ontario, London, Canada
| | - Patrick O’Donoghue
- Department of Biochemistry, The University of Western Ontario, London, Canada
- Department of Chemistry, The University of Western Ontario, London, Canada
| | - Ilka U. Heinemann
- Department of Biochemistry, The University of Western Ontario, London, Canada
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Waltero C, de Abreu LA, Alonso T, Nunes-da-Fonseca R, da Silva Vaz I, Logullo C. TOR as a Regulatory Target in Rhipicephalus microplus Embryogenesis. Front Physiol 2019; 10:965. [PMID: 31417424 PMCID: PMC6684781 DOI: 10.3389/fphys.2019.00965] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Accepted: 07/11/2019] [Indexed: 12/11/2022] Open
Abstract
Embryogenesis is a metabolically intensive process carried out under tightly controlled conditions. The insulin signaling pathway regulates glucose homeostasis and is essential for reproduction in metazoan model species. Three key targets are part of this signaling pathway: protein kinase B (PKB, or AKT), glycogen synthase kinase 3 (GSK-3), and target of rapamycin (TOR). While the role of AKT and GSK-3 has been investigated during tick embryonic development, the role of TOR remains unknown. In this study, TOR and two other downstream effectors, namely S6 kinase (S6K) and eukaryotic translation initiation factor 4E-binding protein 1 (4E-BP1), were investigated in in vitro studies using the tick embryonic cell line BME26. First, we show that exogenous insulin can stimulate TOR transcription. Second, TOR chemical inhibition led to a decrease in BME26 cell viability, loss of membrane integrity, and downregulation of S6K and 4E-BP1 transcription. Conversely, treating BME26 cells with chemical inhibitors of AKT or GSK-3 did not affect S6K and 4E-BP1 transcription, showing that TOR is specifically required to activate its downstream targets. To address the role of TOR in tick reproduction, in vivo studies were performed. Analysis of relative transcription during different stages of tick embryonic development showed different levels of transcription for TOR, and a maternal deposition of S6K and 4E-BP1 transcripts. Injection of TOR double-stranded RNA (dsRNA) into partially fed females led to a slight delay in oviposition, an atypical egg external morphology, decreased vitellin content in eggs, and decreased larval hatching. Taken together, our data show that the TOR signaling pathway is important for tick reproduction, that TOR acts as a regulatory target in Rhipicephalus microplus embryogenesis and represents a promising target for the development of compounds for tick control.
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Affiliation(s)
- Camila Waltero
- Laboratório Integrado de Bioquímica Hatisaburo Masuda and Laboratório Integrado de Ciências Morfofuncionais, Instituto de Biodiversidade e Sustentabilidade NUPEM, Universidade Federal do Rio de Janeiro, Macaé, Brazil
| | - Leonardo Araujo de Abreu
- Laboratório Integrado de Bioquímica Hatisaburo Masuda and Laboratório Integrado de Ciências Morfofuncionais, Instituto de Biodiversidade e Sustentabilidade NUPEM, Universidade Federal do Rio de Janeiro, Macaé, Brazil
- Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular (INCT-EM), Rio de Janeiro, Brazil
| | - Thayná Alonso
- Laboratório Integrado de Bioquímica Hatisaburo Masuda and Laboratório Integrado de Ciências Morfofuncionais, Instituto de Biodiversidade e Sustentabilidade NUPEM, Universidade Federal do Rio de Janeiro, Macaé, Brazil
| | - Rodrigo Nunes-da-Fonseca
- Laboratório Integrado de Bioquímica Hatisaburo Masuda and Laboratório Integrado de Ciências Morfofuncionais, Instituto de Biodiversidade e Sustentabilidade NUPEM, Universidade Federal do Rio de Janeiro, Macaé, Brazil
- Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular (INCT-EM), Rio de Janeiro, Brazil
| | - Itabajara da Silva Vaz
- Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular (INCT-EM), Rio de Janeiro, Brazil
- Centro de Biotecnologia, Faculdade de Veterinária, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Carlos Logullo
- Laboratório Integrado de Bioquímica Hatisaburo Masuda and Laboratório Integrado de Ciências Morfofuncionais, Instituto de Biodiversidade e Sustentabilidade NUPEM, Universidade Federal do Rio de Janeiro, Macaé, Brazil
- Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular (INCT-EM), Rio de Janeiro, Brazil
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76
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Zeng JD, Wu WKK, Wang HY, Li XX. Serine and one-carbon metabolism, a bridge that links mTOR signaling and DNA methylation in cancer. Pharmacol Res 2019; 149:104352. [PMID: 31323332 DOI: 10.1016/j.phrs.2019.104352] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Revised: 07/10/2019] [Accepted: 07/11/2019] [Indexed: 12/24/2022]
Abstract
Mammalian / mechanistic target of rapamycin (mTOR) is a critical sensor of environmental cues that regulates cellular macromolecule synthesis and metabolism in eukaryotes. DNA methylation is the most well-studied epigenetic modification that is capable of regulating gene transcription and affecting genome stability. Both dysregulation of mTOR signaling and DNA methylation patterns have been shown to be closely linked to tumor progression and serve as promising targets for cancer therapy. Although their respective roles in tumorigenesis have been extensively studied, whether molecular interplay exists between them is still largely unknown. In this review, we provide a brief overview of mTOR signaling, DNA methylation as well as related serine and one-carbon metabolism, one of the most critical aspects of metabolic reprogramming in cancer. Based on the latest understanding regarding the regulation of metabolic processes by mTOR signaling as well as interaction between metabolism and epigenetics, we further discuss how serine and one-carbon metabolism may serve as a bridge that links mTOR signaling and DNA methylation to promote tumor growth. Elucidating their relationship may provide novel insight for cancer therapy in the future.
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Affiliation(s)
- Ju-Deng Zeng
- State Key Laboratory of Oncology in South China, Collaborative Innovation center for Cancer Medicine, Sun Yat-sen University cancer center, Guangzhou, Guangdong, China; Department of Anaesthesia and Intensive Care, The Chinese University of Hong Kong, Hong Kong, China
| | - William K K Wu
- Department of Anaesthesia and Intensive Care, The Chinese University of Hong Kong, Hong Kong, China; State Key Laboratory of Digestive diseases, Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong, China
| | - Hui-Yun Wang
- State Key Laboratory of Oncology in South China, Collaborative Innovation center for Cancer Medicine, Sun Yat-sen University cancer center, Guangzhou, Guangdong, China.
| | - Xiao-Xing Li
- State Key Laboratory of Oncology in South China, Collaborative Innovation center for Cancer Medicine, Sun Yat-sen University cancer center, Guangzhou, Guangdong, China.
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77
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Kazyken D, Magnuson B, Bodur C, Acosta-Jaquez HA, Zhang D, Tong X, Barnes TM, Steinl GK, Patterson NE, Altheim CH, Sharma N, Inoki K, Cartee GD, Bridges D, Yin L, Riddle SM, Fingar DC. AMPK directly activates mTORC2 to promote cell survival during acute energetic stress. Sci Signal 2019; 12:12/585/eaav3249. [PMID: 31186373 PMCID: PMC6935248 DOI: 10.1126/scisignal.aav3249] [Citation(s) in RCA: 155] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
AMP-activated protein kinase (AMPK) senses energetic stress and, in turn, promotes catabolic and suppresses anabolic metabolism coordinately to restore energy balance. We found that a diverse array of AMPK activators increased mTOR complex 2 (mTORC2) signaling in an AMPK-dependent manner in cultured cells. Activation of AMPK with the type 2 diabetes drug metformin (GlucoPhage) also increased mTORC2 signaling in liver in vivo and in primary hepatocytes in an AMPK-dependent manner. AMPK-mediated activation of mTORC2 did not result from AMPK-mediated suppression of mTORC1 and thus reduced negative feedback on PI3K flux. Rather, AMPK associated with and directly phosphorylated mTORC2 (mTOR in complex with rictor). As determined by two-stage in vitro kinase assay, phosphorylation of mTORC2 by recombinant AMPK was sufficient to increase mTORC2 catalytic activity toward Akt. Hence, AMPK phosphorylated mTORC2 components directly to increase mTORC2 activity and downstream signaling. Functionally, inactivation of AMPK, mTORC2, and Akt increased apoptosis during acute energetic stress. By showing that AMPK activates mTORC2 to increase cell survival, these data provide a potential mechanism for how AMPK paradoxically promotes tumorigenesis in certain contexts despite its tumor-suppressive function through inhibition of growth-promoting mTORC1. Collectively, these data unveil mTORC2 as a target of AMPK and the AMPK-mTORC2 axis as a promoter of cell survival during energetic stress.
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Affiliation(s)
- Dubek Kazyken
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109-2200, USA
| | - Brian Magnuson
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109-2200, USA
| | - Cagri Bodur
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109-2200, USA
| | - Hugo A. Acosta-Jaquez
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109-2200, USA
| | - Deqiang Zhang
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI 48109-2200, USA
| | - Xin Tong
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI 48109-2200, USA
| | - Tammy M. Barnes
- Department of Internal Medicine and Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI 48109-2200, USA
| | - Gabrielle K. Steinl
- Department of Internal Medicine and Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI 48109-2200, USA
| | - Nicole E. Patterson
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109-2200, USA
| | - Christopher H. Altheim
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109-2200, USA
| | - Naveen Sharma
- School of Kinesiology, Department of Molecular and Integrative Physiology, Institute of Gerontology, University of Michigan, Ann Arbor, MI 48109-2200, USA
| | - Ken Inoki
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI 48109-2200, USA
| | - Gregory D. Cartee
- School of Kinesiology, Department of Molecular and Integrative Physiology, Institute of Gerontology, University of Michigan, Ann Arbor, MI 48109-2200, USA
| | - Dave Bridges
- Department of Nutritional Sciences, University of Michigan, Ann Arbor, MI 48109-2200, USA
| | - Lei Yin
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI 48109-2200, USA
| | | | - Diane C. Fingar
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109-2200, USA.,Corresponding author.
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78
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Lysosome Positioning Influences mTORC2 and AKT Signaling. Mol Cell 2019; 75:26-38.e3. [PMID: 31130364 DOI: 10.1016/j.molcel.2019.05.009] [Citation(s) in RCA: 68] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Revised: 01/18/2019] [Accepted: 04/16/2019] [Indexed: 12/20/2022]
Abstract
Growth factor signaling is initiated at the plasma membrane and propagated through the cytoplasm for eventual relay to intracellular organelles such as lysosomes. The serine/threonine kinase mTOR participates in growth factor signaling as a component of two multi-subunit complexes, mTORC1 and mTORC2. mTORC1 associates with lysosomes, and its activity depends on the positioning of lysosomes within the cytoplasm, although there is no consensus regarding the exact effect of perinuclear versus peripheral distribution. mTORC2 and its substrate kinase AKT have a widespread distribution, but they are thought to act mainly at the plasma membrane. Using cell lines with knockout of components of the lysosome-positioning machinery, we show that perinuclear clustering of lysosomes delays reactivation of not only mTORC1, but also mTORC2 and AKT upon serum replenishment. These experiments demonstrate the existence of pools of mTORC2 and AKT that are sensitive to lysosome positioning.
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79
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Prakash V, Carson BB, Feenstra JM, Dass RA, Sekyrova P, Hoshino A, Petersen J, Guo Y, Parks MM, Kurylo CM, Batchelder JE, Haller K, Hashimoto A, Rundqivst H, Condeelis JS, Allis CD, Drygin D, Nieto MA, Andäng M, Percipalle P, Bergh J, Adameyko I, Farrants AKÖ, Hartman J, Lyden D, Pietras K, Blanchard SC, Vincent CT. Ribosome biogenesis during cell cycle arrest fuels EMT in development and disease. Nat Commun 2019; 10:2110. [PMID: 31068593 PMCID: PMC6506521 DOI: 10.1038/s41467-019-10100-8] [Citation(s) in RCA: 131] [Impact Index Per Article: 26.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Accepted: 04/16/2019] [Indexed: 12/15/2022] Open
Abstract
Ribosome biogenesis is a canonical hallmark of cell growth and proliferation. Here we show that execution of Epithelial-to-Mesenchymal Transition (EMT), a migratory cellular program associated with development and tumor metastasis, is fueled by upregulation of ribosome biogenesis during G1/S arrest. This unexpected EMT feature is independent of species and initiating signal, and is accompanied by release of the repressive nucleolar chromatin remodeling complex (NoRC) from rDNA, together with recruitment of the EMT-driving transcription factor Snai1 (Snail1), RNA Polymerase I (Pol I) and the Upstream Binding Factor (UBF). EMT-associated ribosome biogenesis is also coincident with increased nucleolar recruitment of Rictor, an essential component of the EMT-promoting mammalian target of rapamycin complex 2 (mTORC2). Inhibition of rRNA synthesis in vivo differentiates primary tumors to a benign, Estrogen Receptor-alpha (ERα) positive, Rictor-negative phenotype and reduces metastasis. These findings implicate the EMT-associated ribosome biogenesis program with cellular plasticity, de-differentiation, cancer progression and metastatic disease.
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Affiliation(s)
- Varsha Prakash
- Department of Physiology and Pharmacology, Karolinska Institutet, 171 77, Stockholm, Sweden
- Department of Immunology, Genetics and Pathology, Uppsala University, 751 85, Uppsala, Sweden
| | - Brittany B Carson
- Department of Physiology and Pharmacology, Karolinska Institutet, 171 77, Stockholm, Sweden
| | - Jennifer M Feenstra
- Department of Physiology and Pharmacology, Karolinska Institutet, 171 77, Stockholm, Sweden
- Department of Immunology, Genetics and Pathology, Uppsala University, 751 85, Uppsala, Sweden
| | - Randall A Dass
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY, 10065, USA
| | - Petra Sekyrova
- Department of Immunology, Genetics and Pathology, Uppsala University, 751 85, Uppsala, Sweden
| | - Ayuko Hoshino
- Meyer Cancer Center, Weill Cornell Medicine, New York, NY, 10065, USA
- Department of Pediatrics and Cell and Developmental Biology, Weill Cornell Medicine College, New York, NY, 10065, USA
| | - Julian Petersen
- Department of Physiology and Pharmacology, Karolinska Institutet, 171 77, Stockholm, Sweden
- Department for Brain Research, Medical University of Vienna, 1090, Vienna, Austria
| | - Yuan Guo
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, S-10691, Stockholm, Sweden
| | - Matthew M Parks
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY, 10065, USA
- Meyer Cancer Center, Weill Cornell Medicine, New York, NY, 10065, USA
| | - Chad M Kurylo
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY, 10065, USA
- Meyer Cancer Center, Weill Cornell Medicine, New York, NY, 10065, USA
| | - Jake E Batchelder
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY, 10065, USA
- Meyer Cancer Center, Weill Cornell Medicine, New York, NY, 10065, USA
| | - Kristian Haller
- Department of Laboratory Medicine, Center for Molecular Pathology, Lund University, Lund, SE-223 81, Sweden
| | - Ayako Hashimoto
- Meyer Cancer Center, Weill Cornell Medicine, New York, NY, 10065, USA
- Department of Pediatrics and Cell and Developmental Biology, Weill Cornell Medicine College, New York, NY, 10065, USA
| | - Helene Rundqivst
- Department of Cell and Molecular Biology, Karolinska Institute, Stockholm, SE-171 77, Sweden
| | - John S Condeelis
- Gruss Lipper Biophotonics Center, Albert Einstein College of Medicine, Bronx, 10461, NY, USA
- Department of Pathology, Montefiore Medical Center, Bronx, 10461, NY, USA
| | - C David Allis
- Laboratory of Chromatin Biology and Epigenetics, The Rockefeller University, New York, NY, 10065, USA
| | - Denis Drygin
- Pimera, Inc, 3210 Merryfield Row, San Diego, CA, 92121, USA
| | - M Angela Nieto
- Instituto de Neurociencias, CSIC-UMH, Alicante, 03550, Spain
| | - Michael Andäng
- Department of Immunology, Genetics and Pathology, Uppsala University, 751 85, Uppsala, Sweden
| | - Piergiorgio Percipalle
- Science Division, Biology Program, New York University Abu Dhabi, Abu Dhabi, 129188, UAE
| | - Jonas Bergh
- Department of Oncology and Pathology, Karolinska Institutet and University Hospital, S-171 76, Solna, Sweden
| | - Igor Adameyko
- Department of Physiology and Pharmacology, Karolinska Institutet, 171 77, Stockholm, Sweden
- Department for Brain Research, Medical University of Vienna, 1090, Vienna, Austria
| | - Ann-Kristin Östlund Farrants
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, S-10691, Stockholm, Sweden
| | - Johan Hartman
- Department of Oncology and Pathology, Karolinska Institutet and University Hospital, S-171 76, Solna, Sweden
| | - David Lyden
- Meyer Cancer Center, Weill Cornell Medicine, New York, NY, 10065, USA
- Department of Pediatrics and Cell and Developmental Biology, Weill Cornell Medicine College, New York, NY, 10065, USA
| | - Kristian Pietras
- Department of Laboratory Medicine, Center for Molecular Pathology, Lund University, Lund, SE-223 81, Sweden
| | - Scott C Blanchard
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY, 10065, USA.
- Meyer Cancer Center, Weill Cornell Medicine, New York, NY, 10065, USA.
- Tri-Institutional Training Program in Chemical Biology, Weill Cornell Medicine, New York, NY, 10065, USA.
| | - C Theresa Vincent
- Department of Physiology and Pharmacology, Karolinska Institutet, 171 77, Stockholm, Sweden.
- Department of Immunology, Genetics and Pathology, Uppsala University, 751 85, Uppsala, Sweden.
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY, 10065, USA.
- Meyer Cancer Center, Weill Cornell Medicine, New York, NY, 10065, USA.
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80
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Abstract
In addition to the pivotal roles for histone methylation in the transcriptional regulation, emerging evidence suggests important roles for methylation of non-histone proteins in response to extra-cellular stimulatory events, with implications in governing tumorigenesis. Among the increasing list of non-histone proteins targeted for methylation, the tri-lysine-methylation modification of AKT has been recently identified to fine-tune its kinase activity and oncogenic functions. Moreover, our results implicate the histone methyltransferase SETDB1 as the methyltransferase modifying and activating AKT in a PI3K dependent manner. As such, the oncogenic function of SETDB1 in various cancers may be attributed to tumorigenesis, at least in part, through activating AKT. Therefore, targeting SETDB1, which modulates both epigenetic marks and AKT kinase activity simultaneously, is a potential strategy for novel cancer therapeutics.
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Affiliation(s)
- Jianping Guo
- a Precision Medicine Institute, The First Affiliated Hospital , Sun Yat-sen University , Guangzhou , Guangdong , China.,b Department of Pathology, Beth Israel Deaconess Medical Center , Harvard Medical School , Boston , MA , USA
| | - Wenyi Wei
- b Department of Pathology, Beth Israel Deaconess Medical Center , Harvard Medical School , Boston , MA , USA
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81
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Structural Basis of Autophagy Regulatory Proteins. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1206:287-326. [PMID: 31776992 DOI: 10.1007/978-981-15-0602-4_15] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Autophagy is an evolutionarily conserved lysosome-dependent intracellular degradation process that is essential for the maintenance of cellular homeostasis and adaptation to cellular stresses in eukaryotic cells. The most well-characterized type of autophagy, the macroautophagy, involves the progressive sequestration of cytoplasmic components into dedicated double-membraned vesicles called autophagosomes, which ultimately fuse with lysosomes to initiate the autophagic degradation of the sequestered cargo. In the past decade, our understanding of the molecular mechanism of macroautophagy has significantly evolved, with particular contributions from the biochemical and structural characterizations of autophagy-related proteins. In this chapter, we focus on some autophagy regulatory proteins involved in the macroautophagy pathway, summarize their currently known structures, and discuss their relevant molecular mechanisms from a perspective of structural biology.
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82
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Jian M, Yunjia Z, Zhiying D, Yanduo J, Guocheng J. Interleukin 7 receptor activates PI3K/Akt/mTOR signaling pathway via downregulation of Beclin-1 in lung cancer. Mol Carcinog 2018; 58:358-365. [PMID: 30362635 DOI: 10.1002/mc.22933] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Revised: 10/05/2018] [Accepted: 10/23/2018] [Indexed: 12/29/2022]
Abstract
Interleukin-7(IL-7) can regulate proliferation and apoptosis of cell and also regulate tumor lymphangiogenesis, but whether it regulating autophagy of tumor cells is not well known. We study the relationship between IL-7 and some autophagy-related markers, Beclin 1 and mammalian target of rapamycin (mTOR) and the mechanism of IL-7 in regulating autophagy of human lung cancer cells. We detected expression of Beclin 1 and mTOR in lung cancer cells and their impact on the prognosis of lung cancer patients. Using Western blot and Reverse Transcription PCR, we found that IL-7 activates PI3 K/Akt/mTOR signaling pathway by downregulated the expression of Beclin 1 in lung cancer cell lines. In addition, the expressions of Beclin 1 and mTOR were well correlated with clinical stages and survival of human non-small cell lung cancer (NSCLC) patients. IL-7R, mTOR, and tumor stage were the independent prognosticators in lung cancer. Taken together, our results provided evidence that IL-7 activates PI3 K/Akt/mTOR signaling pathway via Beclin 1 to regulate autophagy in lung cancer cells.
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MESH Headings
- Adenocarcinoma/metabolism
- Adenocarcinoma/secondary
- Adenocarcinoma/therapy
- Apoptosis
- Beclin-1/genetics
- Beclin-1/metabolism
- Biomarkers, Tumor/genetics
- Biomarkers, Tumor/metabolism
- Carcinoma, Non-Small-Cell Lung/metabolism
- Carcinoma, Non-Small-Cell Lung/pathology
- Carcinoma, Non-Small-Cell Lung/therapy
- Carcinoma, Squamous Cell/metabolism
- Carcinoma, Squamous Cell/secondary
- Carcinoma, Squamous Cell/therapy
- Cell Proliferation
- Female
- Follow-Up Studies
- Gene Expression Regulation, Neoplastic
- Humans
- Interleukin-7 Receptor alpha Subunit/genetics
- Interleukin-7 Receptor alpha Subunit/metabolism
- Lung Neoplasms/metabolism
- Lung Neoplasms/pathology
- Lung Neoplasms/therapy
- Male
- Middle Aged
- Neoplasm Metastasis
- Neoplasm Recurrence, Local/metabolism
- Neoplasm Recurrence, Local/pathology
- Neoplasm Recurrence, Local/therapy
- Phosphatidylinositol 3-Kinases/genetics
- Phosphatidylinositol 3-Kinases/metabolism
- Prognosis
- Proto-Oncogene Proteins c-akt/genetics
- Proto-Oncogene Proteins c-akt/metabolism
- Survival Rate
- TOR Serine-Threonine Kinases/genetics
- TOR Serine-Threonine Kinases/metabolism
- Tumor Cells, Cultured
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Affiliation(s)
- Ming Jian
- No.202 Hospital of People Liberation Army of China of China Medical University, Shenyang, Liaoning, China
| | - Zhu Yunjia
- No.202 Hospital of People Liberation Army of China of China Medical University, Shenyang, Liaoning, China
| | - Ding Zhiying
- No.202 Hospital of People Liberation Army of China of China Medical University, Shenyang, Liaoning, China
| | - Jiang Yanduo
- No.202 Hospital of People Liberation Army of China of China Medical University, Shenyang, Liaoning, China
| | - Jiang Guocheng
- No.202 Hospital of People Liberation Army of China of China Medical University, Shenyang, Liaoning, China
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83
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Luo Y, Xu W, Li G, Cui W. Weighing In on mTOR Complex 2 Signaling: The Expanding Role in Cell Metabolism. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2018; 2018:7838647. [PMID: 30510625 PMCID: PMC6232796 DOI: 10.1155/2018/7838647] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/17/2018] [Revised: 08/29/2018] [Accepted: 09/18/2018] [Indexed: 12/21/2022]
Abstract
In all eukaryotes, the mechanistic target of rapamycin (mTOR) signaling emerges as a master regulator of homeostasis, which integrates environmental inputs, including nutrients, energy, and growth factors, to regulate many fundamental cellular processes such as cell growth and metabolism. mTOR signaling functions through two structurally and functionally distinct complexes, mTOR complex 1 (mTORC1) and mTOR complex 2 (mTORC2), which correspond to two major branches of signal output. While mTORC1 is well characterized for its structure, regulation, and function in the last decade, information of mTORC2 signaling is only rapidly expanding in recent years, from structural biology, signaling network, to functional impact. Here we review the recent advances in many aspects of the mTORC2 signaling, with particular focus on its involvement in the control of cell metabolism and its physiological implications in metabolic diseases and aging.
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Affiliation(s)
- Yongting Luo
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, China Agricultural University, Beijing 100193, China
| | - Wenyi Xu
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, China Agricultural University, Beijing 100193, China
| | - Guannan Li
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, China Agricultural University, Beijing 100193, China
| | - Wei Cui
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, China Agricultural University, Beijing 100193, China
- Institute of Reproductive and Developmental Biology, Department of Surgery and Cancer, Imperial College London, Du Cane Road, London W12 0NN, UK
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84
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Moloughney JG, Vega-Cotto NM, Liu S, Patel C, Kim PK, Wu CC, Albaciete D, Magaway C, Chang A, Rajput S, Su X, Werlen G, Jacinto E. mTORC2 modulates the amplitude and duration of GFAT1 Ser-243 phosphorylation to maintain flux through the hexosamine pathway during starvation. J Biol Chem 2018; 293:16464-16478. [PMID: 30201609 DOI: 10.1074/jbc.ra118.003991] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Revised: 08/28/2018] [Indexed: 12/12/2022] Open
Abstract
The mechanistic target of rapamycin (mTOR) controls metabolic pathways in response to nutrients. Recently, we have shown that mTOR complex 2 (mTORC2) modulates the hexosamine biosynthetic pathway (HBP) by promoting the expression of the key enzyme of the HBP, glutamine:fructose-6-phosphate aminotransferase 1 (GFAT1). Here, we found that GFAT1 Ser-243 phosphorylation is also modulated in an mTORC2-dependent manner. In response to glutamine limitation, active mTORC2 prolongs the duration of Ser-243 phosphorylation, albeit at lower amplitude. Blocking glycolysis using 2-deoxyglucose robustly enhances Ser-243 phosphorylation, correlating with heightened mTORC2 activation, increased AMPK activity, and O-GlcNAcylation. However, when 2-deoxyglucose is combined with glutamine deprivation, GFAT1 Ser-243 phosphorylation and mTORC2 activation remain elevated, whereas AMPK activation and O-GlcNAcylation diminish. Phosphorylation at Ser-243 promotes GFAT1 expression and production of GFAT1-generated metabolites including ample production of the HBP end-product, UDP-GlcNAc, despite nutrient starvation. Hence, we propose that the mTORC2-mediated increase in GFAT1 Ser-243 phosphorylation promotes flux through the HBP to maintain production of UDP-GlcNAc when nutrients are limiting. Our findings provide insights on how the HBP is reprogrammed via mTORC2 in nutrient-addicted cancer cells.
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Affiliation(s)
- Joseph G Moloughney
- From the Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854 and
| | - Nicole M Vega-Cotto
- From the Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854 and
| | - Sharon Liu
- From the Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854 and
| | - Chadni Patel
- From the Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854 and
| | - Peter K Kim
- From the Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854 and
| | - Chang-Chih Wu
- From the Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854 and
| | - Danielle Albaciete
- From the Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854 and
| | - Cedric Magaway
- From the Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854 and
| | - Austin Chang
- From the Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854 and
| | - Swati Rajput
- From the Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854 and
| | - Xiaoyang Su
- Department of Medicine, Division of Endocrinology, Child Health Institute of New Jersey, Rutgers, The State University of New Jersey, New Brunswick, New Jersey 08901
| | - Guy Werlen
- From the Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854 and
| | - Estela Jacinto
- From the Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854 and
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85
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Harwood FC, Klein Geltink RI, O’Hara BP, Cardone M, Janke L, Finkelstein D, Entin I, Paul L, Houghton PJ, Grosveld GC. ETV7 is an essential component of a rapamycin-insensitive mTOR complex in cancer. SCIENCE ADVANCES 2018; 4:eaar3938. [PMID: 30258985 PMCID: PMC6156121 DOI: 10.1126/sciadv.aar3938] [Citation(s) in RCA: 73] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Accepted: 08/03/2018] [Indexed: 05/14/2023]
Abstract
The mechanistic target of rapamycin (mTOR) serine/threonine kinase, a critical regulator of cell proliferation, is frequently deregulated in human cancer. Although rapamycin inhibits the two canonical mTOR complexes, mTORC1 and mTORC2, it often shows minimal benefit as an anticancer drug. This is caused by rapamycin resistance of many different tumors, and we show that a third mTOR complex, mTORC3, contributes to this resistance. The ETS (E26 transformation-specific) transcription factor ETV7 interacts with mTOR in the cytoplasm and assembles mTORC3, which is independent of ETV7's transcriptional activity. This complex exhibits bimodal mTORC1/2 activity but is devoid of crucial mTORC1/2 components. Many human cancers activate mTORC3 at considerable frequency, and tumor cell lines that lose mTORC3 expression become rapamycin-sensitive. We show mTORC3's tumorigenicity in a rhabdomyosarcoma mouse model in which transgenic ETV7 expression accelerates tumor onset and promotes tumor penetrance. Discovery of mTORC3 represents an mTOR paradigm shift and identifies a novel target for anticancer drug development.
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Affiliation(s)
- Franklin C. Harwood
- Department of Genetics, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA
| | | | - Brendan P. O’Hara
- Department of Genetics, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA
| | - Monica Cardone
- Department of Genetics, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA
| | - Laura Janke
- Department of Veterinary Pathology, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA
| | - David Finkelstein
- Department of Computational Biology, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA
| | - Igor Entin
- Department of Genetics, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA
| | - Leena Paul
- Department of Genetics, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA
| | - Peter J. Houghton
- Greehey Children’s Cancer Research Institute, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Gerard C. Grosveld
- Department of Genetics, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA
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86
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Cross Talk Networks of Mammalian Target of Rapamycin Signaling With the Ubiquitin Proteasome System and Their Clinical Implications in Multiple Myeloma. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2018; 343:219-297. [PMID: 30712673 DOI: 10.1016/bs.ircmb.2018.06.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Multiple myeloma (MM) is the second most common hematological malignancy and results from the clonal amplification of plasma cells. Despite recent advances in treatment, MM remains incurable with a median survival time of only 5-6years, thus necessitating further insights into MM biology and exploitation of novel therapeutic approaches. Both the ubiquitin proteasome system (UPS) and the PI3K/Akt/mTOR signaling pathways have been implicated in the pathogenesis, and treatment of MM and different lines of evidence suggest a close cross talk between these central cell-regulatory signaling networks. In this review, we outline the interplay between the UPS and mTOR pathways and discuss their implications for the pathophysiology and therapy of MM.
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87
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Walters HE, Cox LS. mTORC Inhibitors as Broad-Spectrum Therapeutics for Age-Related Diseases. Int J Mol Sci 2018; 19:E2325. [PMID: 30096787 PMCID: PMC6121351 DOI: 10.3390/ijms19082325] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Revised: 07/22/2018] [Accepted: 07/30/2018] [Indexed: 02/06/2023] Open
Abstract
Chronological age represents the greatest risk factor for many life-threatening diseases, including neurodegeneration, cancer, and cardiovascular disease; ageing also increases susceptibility to infectious disease. Current efforts to tackle individual diseases may have little impact on the overall healthspan of older individuals, who would still be vulnerable to other age-related pathologies. However, recent progress in ageing research has highlighted the accumulation of senescent cells with chronological age as a probable underlying cause of pathological ageing. Cellular senescence is an essentially irreversible proliferation arrest mechanism that has important roles in development, wound healing, and preventing cancer, but it may limit tissue function and cause widespread inflammation with age. The serine/threonine kinase mTOR (mechanistic target of rapamycin) is a regulatory nexus that is heavily implicated in both ageing and senescence. Excitingly, a growing body of research has highlighted rapamycin and other mTOR inhibitors as promising treatments for a broad spectrum of age-related pathologies, including neurodegeneration, cancer, immunosenescence, osteoporosis, rheumatoid arthritis, age-related blindness, diabetic nephropathy, muscular dystrophy, and cardiovascular disease. In this review, we assess the use of mTOR inhibitors to treat age-related pathologies, discuss possible molecular mechanisms of action where evidence is available, and consider strategies to minimize undesirable side effects. We also emphasize the urgent need for reliable, non-invasive biomarkers of senescence and biological ageing to better monitor the efficacy of any healthy ageing therapy.
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Affiliation(s)
- Hannah E Walters
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK.
| | - Lynne S Cox
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK.
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88
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González-González A, Muñoz-Muela E, Marchal JA, Cara FE, Molina MP, Cruz-Lozano M, Jiménez G, Verma A, Ramírez A, Qian W, Chen W, Kozielski AJ, Elemento O, Martín-Salvago MD, Luque RJ, Rosa-Garrido C, Landeira D, Quintana-Romero M, Rosato RR, García MA, Ramirez-Tortosa CL, Kim H, Rodriguez-Aguayo C, Lopez-Berestein G, Sood AK, Lorente JA, Sánchez-Rovira P, Chang JC, Granados-Principal S. Activating Transcription Factor 4 Modulates TGFβ-Induced Aggressiveness in Triple-Negative Breast Cancer via SMAD2/3/4 and mTORC2 Signaling. Clin Cancer Res 2018; 24:5697-5709. [PMID: 30012564 DOI: 10.1158/1078-0432.ccr-17-3125] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 04/30/2018] [Accepted: 07/11/2018] [Indexed: 11/16/2022]
Abstract
Purpose: On the basis of the identified stress-independent cellular functions of activating transcription factor 4 (ATF4), we reported enhanced ATF4 levels in MCF10A cells treated with TGFβ1. ATF4 is overexpressed in patients with triple-negative breast cancer (TNBC), but its impact on patient survival and the underlying mechanisms remain unknown. We aimed to determine ATF4 effects on patients with breast cancer survival and TNBC aggressiveness, and the relationships between TGFβ and ATF4. Defining the signaling pathways may help us identify a cell signaling-tailored gene signature.Experimental Design: Patient survival data were determined by Kaplan-Meier analysis. Relationship between TGFβ and ATF4, their effects on aggressiveness (tumor proliferation, metastasis, and stemness), and the underlying pathways were analyzed in three TNBC cell lines and in vivo using patient-derived xenografts (PDX).Results: ATF4 overexpression correlated with TNBC patient survival decrease and a SMAD-dependent crosstalk between ATF4 and TGFβ was identified. ATF4 expression inhibition reduced migration, invasiveness, mammosphere-forming efficiency, proliferation, epithelial-mesenchymal transition, and antiapoptotic and stemness marker levels. In PDX models, ATF4 silencing decreased metastases, tumor growth, and relapse after chemotherapy. ATF4 was shown to be active downstream of SMAD2/3/4 and mTORC2, regulating TGFβ/SMAD and mTOR/RAC1-RHOA pathways independently of stress. We defined an eight-gene signature with prognostic potential, altered in 45% of 2,509 patients with breast cancer.Conclusions: ATF4 may represent a valuable prognostic biomarker and therapeutic target in patients with TNBC, and we identified a cell signaling pathway-based gene signature that may contribute to the development of combinatorial targeted therapies for breast cancer. Clin Cancer Res; 24(22); 5697-709. ©2018 AACR.
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Affiliation(s)
- Adrián González-González
- UGC de Oncología Médica, Complejo Hospitalario de Jaén, Jaén, Spain.,GENYO, Centre for Genomics and Oncological Research, Granada, Spain
| | - Esperanza Muñoz-Muela
- UGC de Oncología Médica, Complejo Hospitalario de Jaén, Jaén, Spain.,GENYO, Centre for Genomics and Oncological Research, Granada, Spain
| | - Juan A Marchal
- Instituto de Investigación Biosanitaria de Granada (ibs.GRANADA), Universidad de Granada, Granada, Spain.,Biopathology and Regenerative Medicine Institute (IBIMER), Centre for Biomedical Research (CIBM), University of Granada, Granada, Spain
| | - Francisca E Cara
- UGC de Oncología Médica, Complejo Hospitalario de Jaén, Jaén, Spain.,GENYO, Centre for Genomics and Oncological Research, Granada, Spain
| | - Maria P Molina
- UGC de Oncología Médica, Complejo Hospitalario de Jaén, Jaén, Spain.,GENYO, Centre for Genomics and Oncological Research, Granada, Spain
| | - Marina Cruz-Lozano
- UGC de Oncología Médica, Complejo Hospitalario de Jaén, Jaén, Spain.,GENYO, Centre for Genomics and Oncological Research, Granada, Spain
| | - Gema Jiménez
- Instituto de Investigación Biosanitaria de Granada (ibs.GRANADA), Universidad de Granada, Granada, Spain.,Biopathology and Regenerative Medicine Institute (IBIMER), Centre for Biomedical Research (CIBM), University of Granada, Granada, Spain
| | - Akanksha Verma
- Institute for Computational Biomedicine, Weill Cornell Medical College, New York, New York
| | - Alberto Ramírez
- Houston Methodist Cancer Center, Houston Methodist Hospital, Houston, Texas
| | - Wei Qian
- Institute for Computational Biomedicine, Weill Cornell Medical College, New York, New York
| | - Wen Chen
- Houston Methodist Cancer Center, Houston Methodist Hospital, Houston, Texas
| | | | - Olivier Elemento
- Institute for Computational Biomedicine, Weill Cornell Medical College, New York, New York
| | | | - Rafael J Luque
- UGC de Anatomía Patológica, Complejo Hospitalario de Jaén, Jaén, Spain
| | - Carmen Rosa-Garrido
- FIBAO. Complejo Hospitalario de Jaén, Servicio Andaluz de Salud, Jaén, Spain
| | - David Landeira
- GENYO, Centre for Genomics and Oncological Research, Granada, Spain.,Department of Biochemistry and Molecular Biology II, Faculty of Pharmacy, University of Granada, Granada, Spain
| | - María Quintana-Romero
- GENYO, Centre for Genomics and Oncological Research, Granada, Spain.,Department of Biochemistry and Molecular Biology II, Faculty of Pharmacy, University of Granada, Granada, Spain
| | - Roberto R Rosato
- Houston Methodist Cancer Center, Houston Methodist Hospital, Houston, Texas
| | - Maria A García
- Department of Oncology, Virgen de las Nieves University Hospital, Granada, Spain
| | | | - Hanna Kim
- Texas Tech University Health Sciences Center, School of Pharmacy, Amarillo, Texas
| | - Cristian Rodriguez-Aguayo
- Center for RNA Interference and Non-Coding RNA, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Gabriel Lopez-Berestein
- Center for RNA Interference and Non-Coding RNA, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Anil K Sood
- Center for RNA Interference and Non-Coding RNA, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Jose A Lorente
- GENYO, Centre for Genomics and Oncological Research, Granada, Spain
| | - Pedro Sánchez-Rovira
- UGC de Oncología Médica, Complejo Hospitalario de Jaén, Jaén, Spain.,GENYO, Centre for Genomics and Oncological Research, Granada, Spain
| | - Jenny C Chang
- Houston Methodist Cancer Center, Houston Methodist Hospital, Houston, Texas
| | - Sergio Granados-Principal
- UGC de Oncología Médica, Complejo Hospitalario de Jaén, Jaén, Spain. .,GENYO, Centre for Genomics and Oncological Research, Granada, Spain.,FIBAO. Complejo Hospitalario de Jaén, Servicio Andaluz de Salud, Jaén, Spain
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89
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Jamsheer K M, Shukla BN, Jindal S, Gopan N, Mannully CT, Laxmi A. The FCS-like zinc finger scaffold of the kinase SnRK1 is formed by the coordinated actions of the FLZ domain and intrinsically disordered regions. J Biol Chem 2018; 293:13134-13150. [PMID: 29945970 DOI: 10.1074/jbc.ra118.002073] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Revised: 06/05/2018] [Indexed: 11/06/2022] Open
Abstract
The SNF1-related protein kinase 1 (SnRK1) is a heterotrimeric eukaryotic kinase that interacts with diverse proteins and regulates their activity in response to starvation and stress signals. Recently, the FCS-like zinc finger (FLZ) proteins were identified as a potential scaffold for SnRK1 in plants. However, the evolutionary and mechanistic aspect of this complex formation is currently unknown. Here, in silico analyses predicted that FLZ proteins possess conserved intrinsically disordered regions (IDRs) with a propensity for protein binding in the N and C termini across the plant lineage. We observed that the Arabidopsis FLZ proteins promiscuously interact with SnRK1 subunits, which formed different isoenzyme complexes. The FLZ domain was essential for mediating the interaction with SnRK1α subunits, whereas the IDRs in the N termini facilitated interactions with the β and βγ subunits of SnRK1. Furthermore, the IDRs in the N termini were important for mediating dimerization of different FLZ proteins. Of note, the interaction of FLZ with SnRK1 was confined to cytoplasmic foci, which colocalized with the endoplasmic reticulum. An evolutionary analysis revealed that in general, the IDR-rich regions are under more relaxed selection than the FLZ domain. In summary, the findings in our study reveal the structural details, origin, and evolution of a land plant-specific scaffold of SnRK1 formed by the coordinated actions of IDRs and structured regions in the FLZ proteins. We propose that the FLZ protein complex might be involved in providing flexibility, thus enhancing the binding repertoire of the SnRK1 hub in land plants.
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Affiliation(s)
- Muhammed Jamsheer K
- From the National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi-110067 and
| | - Brihaspati N Shukla
- From the National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi-110067 and
| | - Sunita Jindal
- From the National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi-110067 and
| | - Nandu Gopan
- the Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bengaluru-560064, India
| | | | - Ashverya Laxmi
- From the National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi-110067 and
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90
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Khan MW, Layden BT, Chakrabarti P. Inhibition of mTOR complexes protects cancer cells from glutamine starvation induced cell death by restoring Akt stability. Biochim Biophys Acta Mol Basis Dis 2018; 1864:2040-2052. [DOI: 10.1016/j.bbadis.2018.03.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2017] [Revised: 03/09/2018] [Accepted: 03/13/2018] [Indexed: 12/11/2022]
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91
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Abstract
Translation is a key step in the regulation of gene expression and one of the most energy-consuming processes in the cell. In response to various stimuli, multiple signaling pathways converge on the translational machinery to regulate its function. To date, the roles of phosphoinositide 3-kinase (PI3K)/AKT and the mitogen-activated protein kinase (MAPK) pathways in the regulation of translation are among the best understood. Both pathways engage the mechanistic target of rapamycin (mTOR) to regulate a variety of components of the translational machinery. While these pathways regulate protein synthesis in homeostasis, their dysregulation results in aberrant translation leading to human diseases, including diabetes, neurological disorders, and cancer. Here we review the roles of the PI3K/AKT and MAPK pathways in the regulation of mRNA translation. We also highlight additional signaling mechanisms that have recently emerged as regulators of the translational apparatus.
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92
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Who does TORC2 talk to? Biochem J 2018; 475:1721-1738. [PMID: 29794170 DOI: 10.1042/bcj20180130] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2018] [Revised: 04/19/2018] [Accepted: 04/23/2018] [Indexed: 12/21/2022]
Abstract
The target of rapamycin (TOR) is a protein kinase that, by forming complexes with partner proteins, governs diverse cellular signalling networks to regulate a wide range of processes. TOR thus plays central roles in maintaining normal cellular functions and, when dysregulated, in diverse diseases. TOR forms two distinct types of multiprotein complexes (TOR complexes 1 and 2, TORC1 and TORC2). TORC1 and TORC2 differ in their composition, their control and their substrates, so that they play quite distinct roles in cellular physiology. Much effort has been focused on deciphering the detailed regulatory links within the TOR pathways and the structure and control of TOR complexes. In this review, we summarize recent advances in understanding mammalian (m) TORC2, its structure, its regulation, and its substrates, which link TORC2 signalling to the control of cell functions. It is now clear that TORC2 regulates several aspects of cell metabolism, including lipogenesis and glucose transport. It also regulates gene transcription, the cytoskeleton, and the activity of a subset of other protein kinases.
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93
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Mecca C, Giambanco I, Bruscoli S, Bereshchenko O, Fioretti B, Riccardi C, Donato R, Arcuri C. PP242 Counteracts Glioblastoma Cell Proliferation, Migration, Invasiveness and Stemness Properties by Inhibiting mTORC2/AKT. Front Cell Neurosci 2018; 12:99. [PMID: 29692710 PMCID: PMC5902688 DOI: 10.3389/fncel.2018.00099] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Accepted: 03/23/2018] [Indexed: 12/29/2022] Open
Abstract
Glioblastoma multiforme (GBM) is the most malignant brain tumor and is associated with poor prognosis due to its thorny localization, lack of efficacious therapies and complex biology. Among the numerous pathways driving GBM biology studied so far, PTEN/phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K)/AKT/mechanistic target of rapamycin (mTOR) signaling plays a pivotal role, as it controls cell survival, proliferation and metabolism and is involved in stem cell maintenance. In front of recent and numerous evidences highlighting mTOR upregulation in GBM, all the strategies developed to inhibit this pathway have been substantially unsuccessful. Our study focused on mTOR complex 2 (mTORC2) to understand its involvement in GBM cell growth, proliferation, migration and invasiveness. We utilized an in vitro model, characterized by various genetic alterations (i.e., GL15, U257, U87MG and U118MG cell lines) in order to achieve the clonal heterogeneity observed in vivo. Additionally, being the U87MG cell line endowed with glioblastoma stem cells (GSCs), we also investigated the role of the PTEN/PI3K/AKT/mTOR pathway in this specific cell population, which is responsible for GBM relapse. We provide further insights that explain the reasons for the failure of numerous clinical trials conducted to date targeting PI3K or mTOR complex 1 (mTORC1) with rapamycin and its analogs. Additionally, we show that mTORC2 might represent a potential clinically valuable target for GBM treatment, as proliferation, migration and GSC maintenance appear to be mTORC2-dependent. In this context, we demonstrate that the novel ATP-competitive mTOR inhibitor PP242 effectively targets both mTORC1 and mTORC2 activation and counteracts cell proliferation via the induction of high autophagy levels, besides reducing cell migration, invasiveness and stemness properties.
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Affiliation(s)
- Carmen Mecca
- Department of Experimental Medicine, Perugia Medical School, University of Perugia, Perugia, Italy
| | - Ileana Giambanco
- Department of Experimental Medicine, Perugia Medical School, University of Perugia, Perugia, Italy
| | - Stefano Bruscoli
- Department of Medicine, Perugia Medical School, University of Perugia, Perugia, Italy
| | - Oxana Bereshchenko
- Department of Medicine, Perugia Medical School, University of Perugia, Perugia, Italy
| | - Bernard Fioretti
- Department of Chemistry, Biology and Biotechnology, University of Perugia, Perugia, Italy
| | - Carlo Riccardi
- Department of Medicine, Perugia Medical School, University of Perugia, Perugia, Italy
| | - Rosario Donato
- Department of Experimental Medicine, Perugia Medical School, University of Perugia, Perugia, Italy.,Centro Universitario per la Ricerca sulla Genomica Funzionale, University of Perugia, Perugia, Italy
| | - Cataldo Arcuri
- Department of Experimental Medicine, Perugia Medical School, University of Perugia, Perugia, Italy
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94
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Jamsheer K M, Sharma M, Singh D, Mannully CT, Jindal S, Shukla BN, Laxmi A. FCS-like zinc finger 6 and 10 repress SnRK1 signalling in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2018; 94:232-245. [PMID: 29406622 DOI: 10.1111/tpj.13854] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Revised: 01/05/2018] [Accepted: 01/17/2018] [Indexed: 05/14/2023]
Abstract
SNF1-related protein kinase 1 (SnRK1) is a central regulator of plant growth during energy starvation. The FCS-like zinc finger (FLZ) proteins have recently been identified as adaptor proteins which facilitate the interaction of SnRK1 with other proteins. In this study, we found that two starvation-induced FLZ genes, FLZ6 and FLZ10, work as repressors of SnRK1 signalling. The reduced expression of these genes resulted in an increase in the level of SnRK1α1, which is the major catalytic subunit of SnRK1. This lead to a concomitant increase in phosphorylated protein and SnRK1 activity in the flz6 and flz10 mutants. FLZ6 and FLZ10 specifically interact with SnRK1α subunits in the cytoplasmic foci, which co-localized with the endoplasmic reticulum. In physiological assays, similar to the SnRK1α1 overexpression line, flz mutants showed compromised growth. Further, growth promotion in response to favourable growth conditions was found to be attenuated in the mutants. The enhanced SnRK1 activity in the mutants resulted in a reduction in the level of phosphorylated RIBOSOMAL S6 KINASE and the expression of E2Fa and its targets, indicating that TARGET OF RAPAMYCIN-dependent promotion of protein synthesis and cell cycle progression is impaired. Taken together, this study uncovers a plant-specific modulation of SnRK1 signalling.
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Affiliation(s)
- Muhammed Jamsheer K
- National Institute of Plant Genome Research, Aruna Asaf Ali Road, New Delhi, 110067, India
| | - Manvi Sharma
- National Institute of Plant Genome Research, Aruna Asaf Ali Road, New Delhi, 110067, India
| | - Dhriti Singh
- National Institute of Plant Genome Research, Aruna Asaf Ali Road, New Delhi, 110067, India
| | - Chanchal T Mannully
- National Institute of Plant Genome Research, Aruna Asaf Ali Road, New Delhi, 110067, India
| | - Sunita Jindal
- National Institute of Plant Genome Research, Aruna Asaf Ali Road, New Delhi, 110067, India
| | - Brihaspati N Shukla
- National Institute of Plant Genome Research, Aruna Asaf Ali Road, New Delhi, 110067, India
| | - Ashverya Laxmi
- National Institute of Plant Genome Research, Aruna Asaf Ali Road, New Delhi, 110067, India
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95
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mTORC2 Signaling: A Path for Pancreatic β Cell's Growth and Function. J Mol Biol 2018; 430:904-918. [PMID: 29481838 DOI: 10.1016/j.jmb.2018.02.013] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Revised: 02/14/2018] [Accepted: 02/14/2018] [Indexed: 12/16/2022]
Abstract
The mechanistic target of rapamycin (mTOR) signaling pathway is an evolutionary conserved pathway that senses signals from nutrients and growth factors to regulate cell growth, metabolism and survival. mTOR acts in two biochemically and functionally distinct complexes, mTOR complex 1 (mTORC1) and 2 (mTORC2), which differ in terms of regulatory mechanisms, substrate specificity and functional outputs. While mTORC1 signaling has been extensively studied in islet/β-cell biology, recent findings demonstrate a distinct role for mTORC2 in the regulation of pancreatic β-cell function and mass. mTORC2, a key component of the growth factor receptor signaling, is declined in β cells under diabetogenic conditions and in pancreatic islets from patients with type 2 diabetes. β cell-selective mTORC2 inactivation leads to glucose intolerance and acceleration of diabetes as a result of reduced β-cell mass, proliferation and impaired glucose-stimulated insulin secretion. Thereby, many mTORC2 targets, such as AKT, PKC, FOXO1, MST1 and cell cycle regulators, play an important role in β-cell survival and function. This indicates mTORC2 as important pathway for the maintenance of β-cell homeostasis, particularly to sustain proper β-cell compensatory response in the presence of nutrient overload and metabolic demand. This review summarizes recent emerging advances on the contribution of mTORC2 and its associated signaling on the regulation of glucose metabolism and functional β-cell mass under physiological and pathophysiological conditions in type 2 diabetes.
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96
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Non-equilibrium coupling of protein structure and function to translation-elongation kinetics. Curr Opin Struct Biol 2018; 49:94-103. [PMID: 29414517 DOI: 10.1016/j.sbi.2018.01.005] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 12/21/2017] [Accepted: 01/02/2018] [Indexed: 01/23/2023]
Abstract
Protein folding research has been dominated by the assumption that thermodynamics determines protein structure and function. And that when the folding process is compromised in vivo the proteostasis machinery-chaperones, deaggregases, the proteasome-work to restore proteins to their soluble, functional form or degrade them to maintain the cellular pool of proteins in a quasi-equilibrium state. During the past decade, however, more and more proteins have been identified for which altering only their speed of synthesis alters their structure and function, the efficiency of the down-stream processes they take part in, and cellular phenotype. Indeed, evidence has emerged that evolutionary selection pressures have encoded translation-rate information into mRNA molecules to coordinate diverse co-translational processes. Thus, non-equilibrium physics can play a fundamental role in influencing nascent protein behavior, mRNA sequence evolution, and disease. Here, we discuss how our understanding of this phenomenon is being advanced by the application of theoretical tools from the physical sciences.
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Schepetilnikov M, Ryabova LA. Recent Discoveries on the Role of TOR (Target of Rapamycin) Signaling in Translation in Plants. PLANT PHYSIOLOGY 2018; 176:1095-1105. [PMID: 29122989 PMCID: PMC5813564 DOI: 10.1104/pp.17.01243] [Citation(s) in RCA: 75] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Accepted: 11/09/2017] [Indexed: 05/18/2023]
Abstract
TOR signaling regulates plant translation via a specific translation initiation mechanism: reinitiation.
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Affiliation(s)
- Mikhail Schepetilnikov
- Institut de Biologie Moléculaire des Plantes, Centre National de la Recherche Scientifique, UPR 2357, Université de Strasbourg, 67084 Strasbourg, France
| | - Lyubov A Ryabova
- Institut de Biologie Moléculaire des Plantes, Centre National de la Recherche Scientifique, UPR 2357, Université de Strasbourg, 67084 Strasbourg, France
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98
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Paquette M, El-Houjeiri L, Pause A. mTOR Pathways in Cancer and Autophagy. Cancers (Basel) 2018; 10:cancers10010018. [PMID: 29329237 PMCID: PMC5789368 DOI: 10.3390/cancers10010018] [Citation(s) in RCA: 211] [Impact Index Per Article: 35.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Revised: 12/22/2017] [Accepted: 01/09/2018] [Indexed: 12/11/2022] Open
Abstract
TOR (target of rapamycin), an evolutionarily-conserved serine/threonine kinase, acts as a central regulator of cell growth, proliferation and survival in response to nutritional status, growth factor, and stress signals. It plays a crucial role in coordinating the balance between cell growth and cell death, depending on cellular conditions and needs. As such, TOR has been identified as a key modulator of autophagy for more than a decade, and several deregulations of this pathway have been implicated in a variety of pathological disorders, including cancer. At the molecular level, autophagy regulates several survival or death signaling pathways that may decide the fate of cancer cells; however, the relationship between autophagy pathways and cancer are still nascent. In this review, we discuss the recent cellular signaling pathways regulated by TOR, their interconnections to autophagy, and the clinical implications of TOR inhibitors in cancer.
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Affiliation(s)
- Mathieu Paquette
- Goodman Cancer Research Center, McGill University, Montréal, QC H3A 1A3, Canada.
- Department of Biochemistry, McGill University, Montréal, QC H3G 1Y6, Canada.
| | - Leeanna El-Houjeiri
- Goodman Cancer Research Center, McGill University, Montréal, QC H3A 1A3, Canada.
- Department of Biochemistry, McGill University, Montréal, QC H3G 1Y6, Canada.
| | - Arnim Pause
- Goodman Cancer Research Center, McGill University, Montréal, QC H3A 1A3, Canada.
- Department of Biochemistry, McGill University, Montréal, QC H3G 1Y6, Canada.
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99
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Xu B, Zhang Y, Zhan S, Wang X, Zhang H, Meng X, Ge W. Proteomic Profiling of Brain and Testis Reveals the Diverse Changes in Ribosomal Proteins in fmr1 Knockout Mice. Neuroscience 2017; 371:469-483. [PMID: 29292077 DOI: 10.1016/j.neuroscience.2017.12.023] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Revised: 12/15/2017] [Accepted: 12/18/2017] [Indexed: 01/01/2023]
Abstract
Fragile X syndrome (FXS), the leading cause of inherited forms of mental retardation and autism, is caused by the transcriptional silencing of fmr1 encoding the fragile X mental retardation protein (FMRP). FMRP is an RNA-binding protein that is a widely expressed, but primarily in the brain and testis, and associated approximately 4% of transcripts. Macro-orchidism is a common symptom associated with FXS both in humans and mice. Thus, we analyze the pooled samples of cerebral cortex, hippocampus and testis from both the fmr1-KO and wild-type mice by a LC-MS/MS proteomic study. Among the identified proteins, most of those showing significant changes in expression were up- or downregulated in the absence of FMRP. Proteins (FMRP, RPS8, RPL23a and ATPIF1, RPL6, GAP43, MTCH2 and MPZ in brain, and FMRP, CAH3, AKR1B7 and C9 in testis) identified by MS/MS were also verified by Western blotting. The Gene Ontology and WikiPathways analysis revealed that the differentially expressed proteins were clustered in the polyribosome and RNA-binding protein categories in both cerebral cortex and hippocampus, but not in testis. Although this study was limited by the little number of samples, our results provide detailed insights into the ribosomal protein profiles of cerebral cortex, hippocampus and testis in the absence of FMRP. Our studies also provide a better understanding of protein profile changes and the underlying dysregulated pathways arising from fmr1 silencing in FXS.
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Affiliation(s)
- Benhong Xu
- Affiliated Hospital of Hebei University, No. 212, Yu Hua East Road, Nan Shi District, Baoding, Hebei 071000, China; State Key Laboratory of Medical Molecular Biology & Department of Immunology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, No. 5 Dongdansantiao, Dongcheng District, Beijing 100005, China; Key Laboratory of Modern Toxicology of Shenzhen, Institute of Toxicology, Shenzhen Center for Disease Control and Prevention, Shenzhen 518055, China
| | - Yusheng Zhang
- State Key Laboratory of Medical Molecular Biology & Department of Immunology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, No. 5 Dongdansantiao, Dongcheng District, Beijing 100005, China
| | - Shaohua Zhan
- State Key Laboratory of Medical Molecular Biology & Department of Immunology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, No. 5 Dongdansantiao, Dongcheng District, Beijing 100005, China
| | - Xia Wang
- State Key Laboratory of Medical Molecular Biology & Department of Immunology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, No. 5 Dongdansantiao, Dongcheng District, Beijing 100005, China
| | - Haisong Zhang
- Affiliated Hospital of Hebei University, No. 212, Yu Hua East Road, Nan Shi District, Baoding, Hebei 071000, China
| | - Xianbin Meng
- MOE Key Laboratory of Bioinformatics, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Wei Ge
- Affiliated Hospital of Hebei University, No. 212, Yu Hua East Road, Nan Shi District, Baoding, Hebei 071000, China; State Key Laboratory of Medical Molecular Biology & Department of Immunology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, No. 5 Dongdansantiao, Dongcheng District, Beijing 100005, China.
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100
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Yang CS, Melhuish TA, Spencer A, Ni L, Hao Y, Jividen K, Harris T, Snow C, Frierson H, Wotton D, Paschal BM. The protein kinase C super-family member PKN is regulated by mTOR and influences differentiation during prostate cancer progression. Prostate 2017; 77:1452-1467. [PMID: 28875501 PMCID: PMC5669364 DOI: 10.1002/pros.23400] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Accepted: 07/31/2017] [Indexed: 11/07/2022]
Abstract
BACKGROUND Phosphoinositide-3 (PI-3) kinase signaling has a pervasive role in cancer. One of the key effectors of PI-3 kinase signaling is AKT, a kinase that promotes growth and survival in a variety of cancers. Genetically engineered mouse models of prostate cancer have shown that AKT signaling is sufficient to induce prostatic epithelial neoplasia (PIN), but insufficient for progression to adenocarcinoma. This contrasts with the phenotype of mice with prostate-specific deletion of Pten, where excessive PI-3 kinase signaling induces both PIN and locally invasive carcinoma. We reasoned that additional PI-3 kinase effector kinases promote prostate cancer progression via activities that provide biological complementarity to AKT. We focused on the PKN kinase family members, which undergo activation in response to PI-3 kinase signaling, show expression changes in prostate cancer, and contribute to cell motility pathways in cancer cells. METHODS PKN kinase activity was measured by incorporation of 32 P into protein substrates. Phosphorylation of the turn-motif (TM) in PKN proteins by mTOR was analyzed using the TORC2-specific inhibitor torin and a PKN1 phospho-TM-specific antibody. Amino acid substitutions in the TM of PKN were engineered and assayed for effects on kinase activity. Cell motility-related functions and PKN localization was analyzed by depletion approaches and immunofluorescence microscopy, respectively. The contribution of PKN proteins to prostate tumorigenesis was characterized in several mouse models that express PKN transgenes. The requirement for PKN activity in prostate cancer initiated by loss of phosphatase and tensin homolog deleted on chromosome 10 (Pten), and the potential redundancy between PKN isoforms, was analyzed by prostate-specific deletion of Pkn1, Pkn2, and Pten. RESULTS AND CONCLUSIONS PKN1 and PKN2 contribute to motility pathways in human prostate cancer cells. PKN1 and PKN2 kinase activity is regulated by TORC2-dependent phosphorylation of the TM, which together with published data indicates that PKN proteins receive multiple PI-3 kinase-dependent inputs. Transgenic expression of active AKT and PKN1 is not sufficient for progression beyond PIN. Moreover, Pkn1 is not required for tumorigenesis initiated by loss of Pten. Triple knockout of Pten, Pkn1, and Pkn2 in mouse prostate results in squamous cell carcinoma, an uncommon but therapy-resistant form of prostate cancer.
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Affiliation(s)
- Chun-Song Yang
- Center for Cell Signaling, University of Virginia, Charlottesville, VA, 22908, USA
| | - Tiffany A. Melhuish
- Center for Cell Signaling, University of Virginia, Charlottesville, VA, 22908, USA
| | - Adam Spencer
- Center for Cell Signaling, University of Virginia, Charlottesville, VA, 22908, USA
| | - Li Ni
- Center for Cell Signaling, University of Virginia, Charlottesville, VA, 22908, USA
| | - Yi Hao
- Center for Cell Signaling, University of Virginia, Charlottesville, VA, 22908, USA
| | - Kasey Jividen
- Center for Cell Signaling, University of Virginia, Charlottesville, VA, 22908, USA
| | - Thurl Harris
- Department of Pharmacology, University of Virginia, Charlottesville, VA, 22908, USA
| | - Chelsi Snow
- Center for Cell Signaling, University of Virginia, Charlottesville, VA, 22908, USA
| | - Henry Frierson
- Department of Pathology, University of Virginia, Charlottesville, VA, 22908, USA
| | - David Wotton
- Center for Cell Signaling, University of Virginia, Charlottesville, VA, 22908, USA
- Department of Biochemistry and Molecular Genetics, University of Virginia, VA, 22908, USA
| | - Bryce M. Paschal
- Center for Cell Signaling, University of Virginia, Charlottesville, VA, 22908, USA
- Department of Biochemistry and Molecular Genetics, University of Virginia, VA, 22908, USA
- corresponding author: Bryce M. Paschal, Center for Cell Signaling, Department of Biochemistry & Molecular Genetics, University of Virginia, Room 7021 West Complex, Box 800577, Health Sciences Center, 1400 Jefferson Park Avenue, Charlottesville, VA 22908-0577, , Office 434.243.6521, Lab 434.924.1532, Fax 434.924.1236
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