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Zhao T, Fan J, Abu-Zaid A, Burley SK, Zheng XS. Nuclear mTOR Signaling Orchestrates Transcriptional Programs Underlying Cellular Growth and Metabolism. Cells 2024; 13:781. [PMID: 38727317 PMCID: PMC11083943 DOI: 10.3390/cells13090781] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2024] [Revised: 04/26/2024] [Accepted: 05/01/2024] [Indexed: 05/13/2024] Open
Abstract
mTOR is a central regulator of cell growth and metabolism in response to mitogenic and nutrient signals. Notably, mTOR is not only found in the cytoplasm but also in the nucleus. This review highlights direct involvement of nuclear mTOR in regulating transcription factors, orchestrating epigenetic modifications, and facilitating chromatin remodeling. These effects intricately modulate gene expression programs associated with growth and metabolic processes. Furthermore, the review underscores the importance of nuclear mTOR in mediating the interplay between metabolism and epigenetic modifications. By integrating its functions in nutrient signaling and gene expression related to growth and metabolism, nuclear mTOR emerges as a central hub governing cellular homeostasis, malignant transformation, and cancer progression. Better understanding of nuclear mTOR signaling has the potential to lead to novel therapies against cancer and other growth-related diseases.
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Affiliation(s)
- Tinghan Zhao
- Rutgers Cancer Institute of New Jersey, Rutgers, The State University of New Jersey, New Brunswick, NJ 08901, USA
| | - Jialin Fan
- Rutgers Cancer Institute of New Jersey, Rutgers, The State University of New Jersey, New Brunswick, NJ 08901, USA
| | - Ahmed Abu-Zaid
- Rutgers Cancer Institute of New Jersey, Rutgers, The State University of New Jersey, New Brunswick, NJ 08901, USA
| | - Stephen K. Burley
- Rutgers Cancer Institute of New Jersey, Rutgers, The State University of New Jersey, New Brunswick, NJ 08901, USA
- RCSB Protein Data Bank and Institute for Quantitative Biomedicine, Rutgers, The State University of New Jersey, 174 Frelinghuysen Road, Piscataway, NJ 08854, USA
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, 174 Frelinghuysen Road, Piscataway, NJ 08854, USA
| | - X.F. Steven Zheng
- Rutgers Cancer Institute of New Jersey, Rutgers, The State University of New Jersey, New Brunswick, NJ 08901, USA
- Department of Pharmacology, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
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2
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Wehle DT, Bass CS, Sulc J, Mirzaa G, Smith SEP. Protein interaction network analysis of mTOR signaling reveals modular organization. J Biol Chem 2023; 299:105271. [PMID: 37741456 PMCID: PMC10594569 DOI: 10.1016/j.jbc.2023.105271] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Revised: 09/11/2023] [Accepted: 09/13/2023] [Indexed: 09/25/2023] Open
Abstract
The mammalian target of rapamycin (mTOR) is a serine-threonine kinase that acts as a central mediator of translation and plays important roles in cell growth, synaptic plasticity, cancer, and a wide range of developmental disorders. The signaling cascade linking lipid kinases (phosphoinositide 3-kinases), protein kinases (AKT), and translation initiation complexes (EIFs) to mTOR has been extensively modeled, but does not fully describe mTOR system behavior. Here, we use quantitative multiplex coimmunoprecipitation to monitor a protein interaction network (PIN) composed of 300+ binary interactions among mTOR-related proteins. Using a simple model system of serum-deprived or fresh-media-fed mouse 3T3 fibroblasts, we observed extensive PIN remodeling involving 27+ individual protein interactions after 1 h, despite phosphorylation changes observed after only 5 min. Using small molecule inhibitors of phosphoinositide 3-kinase, AKT, mTOR, MEK and ERK, we define subsets of the PIN, termed "modules", that respond differently to each inhibitor. Using primary fibroblasts from individuals with overgrowth disorders caused by pathogenic PIK3CA or MTOR variants, we find that hyperactivation of mTOR pathway components is reflected in a hyperactive PIN. Our data define a "modular" organization of the mTOR PIN in which coordinated groups of interactions respond to the activation or inhibition of distinct nodes, and demonstrate that kinase inhibitors affect the modular network architecture in a complex manner, inconsistent with simple linear models of signal transduction.
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Affiliation(s)
- Devin T Wehle
- Graduate Program in Neuroscience, University of Washington, Seattle, Washington, USA; Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington, USA
| | - Carter S Bass
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington, USA
| | - Josef Sulc
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington, USA
| | - Ghayda Mirzaa
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington, USA; Department of Pediatrics, University of Washington School of Medicine, Seattle, Washington, USA; Brotman Baty Institute for Precision Medicine, Seattle, Washington, USA
| | - Stephen E P Smith
- Graduate Program in Neuroscience, University of Washington, Seattle, Washington, USA; Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington, USA; Department of Pediatrics, University of Washington School of Medicine, Seattle, Washington, USA.
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3
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Wehle DT, Bass CS, Sulc J, Mirzaa G, Smith SEP. Protein interaction network analysis of mTOR signaling reveals modular organization. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.04.552011. [PMID: 37577705 PMCID: PMC10418199 DOI: 10.1101/2023.08.04.552011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/15/2023]
Abstract
The mammalian target of rapamycin (mTOR) is a serine-threonine kinase that acts as a central mediator of translation, and plays important roles in cell growth, synaptic plasticity, cancer, and a wide range of developmental disorders. The signaling cascade linking lipid kinases (PI3Ks), protein kinases (AKT) and translation initiation complexes (EIFs) to mTOR has been extensively modeled, but does not fully describe mTOR system behavior. Here, we use quantitative multiplex co-immunoprecipitation to monitor a protein interaction network (PIN) composed of 300+ binary interactions among mTOR-related proteins. Using a simple model system of serum deprived or fresh-media-fed mouse 3T3 fibroblasts, we observed extensive PIN remodeling involving 27+ individual protein interactions after one hour, despite phosphorylation changes observed after only five minutes. Using small molecule inhibitors of PI3K, AKT, mTOR, MEK and ERK, we define subsets of the PIN, termed 'modules', that respond differently to each inhibitor. Using primary fibroblasts from individuals with overgrowth disorders caused by pathogenic PIK3CA or MTOR variants, we find that hyperactivation of mTOR pathway components is reflected in a hyperactive PIN. Our data define a "modular" organization of the mTOR PIN in which coordinated groups of interactions respond to activation or inhibition of distinct nodes, and demonstrate that kinase inhibitors affect the modular network architecture in a complex manner, inconsistent with simple linear models of signal transduction.
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Affiliation(s)
- Devin T Wehle
- Graduate Program in Neuroscience, University of Washington, Seattle, WA, USA
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, USA
| | - Carter S Bass
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, USA
| | - Josef Sulc
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, USA
| | - Ghayda Mirzaa
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, USA
- Department of Pediatrics, University of Washington School of Medicine, Seattle, WA, USA
- Brotman Baty Institute for Precision Medicine, Seattle, WA, USA
| | - Stephen E P Smith
- Graduate Program in Neuroscience, University of Washington, Seattle, WA, USA
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, USA
- Department of Pediatrics, University of Washington School of Medicine, Seattle, WA, USA
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4
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Marques-Ramos A, Cervantes R. Expression of mTOR in normal and pathological conditions. Mol Cancer 2023; 22:112. [PMID: 37454139 PMCID: PMC10349476 DOI: 10.1186/s12943-023-01820-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2023] [Accepted: 07/08/2023] [Indexed: 07/18/2023] Open
Abstract
The mechanistic/mammalian target of rapamycin (mTOR), a protein discovered in 1991, integrates a complex pathway with a key role in maintaining cellular homeostasis. By comprising two functionally distinct complexes, mTOR complex 1 (mTORC1) and mTORC2, it is a central cellular hub that integrates intra- and extracellular signals of energy, nutrient, and hormone availability, modulating the molecular responses to acquire a homeostatic state through the regulation of anabolic and catabolic processes. Accordingly, dysregulation of mTOR pathway has been implicated in a variety of human diseases. While major advances have been made regarding the regulators and effectors of mTOR signaling pathway, insights into the regulation of mTOR gene expression are beginning to emerge. Here, we present the current available data regarding the mTOR expression regulation at the level of transcription, translation and mRNA stability and systematize the current knowledge about the fluctuations of mTOR expression observed in several diseases, both cancerous and non-cancerous. In addition, we discuss whether mTOR expression changes can be used as a biomarker for diagnosis, disease progression, prognosis and/or response to therapeutics. We believe that our study will contribute for the implementation of new disease biomarkers based on mTOR as it gives an exhaustive perspective about the regulation of mTOR gene expression in both normal and pathological conditions.
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Affiliation(s)
- A Marques-Ramos
- H&TRC-Health & Technology Research Center, ESTeSL-Escola Superior de Tecnologia da Saúde, Instituto Politécnico de Lisboa, Lisbon, Portugal.
| | - R Cervantes
- H&TRC-Health & Technology Research Center, ESTeSL-Escola Superior de Tecnologia da Saúde, Instituto Politécnico de Lisboa, Lisbon, Portugal
- Public Health Research Centre, NOVA National School of Public Health, Universidade Nova de Lisboa, Lisbon, Portugal
- Comprehensive Health Research Center (CHRC), Lisbon, Portugal
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5
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Nanba D, Sakabe JI, Mosig J, Brouard M, Toki F, Shimokawa M, Kamiya M, Braschler T, Azzabi F, Droz-Georget Lathion S, Johnsson K, Roy K, Schmid CD, Bureau JB, Rochat A, Barrandon Y. Low temperature and mTOR inhibition favor stem cell maintenance in human keratinocyte cultures. EMBO Rep 2023:e55439. [PMID: 37139607 DOI: 10.15252/embr.202255439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Revised: 03/26/2023] [Accepted: 04/14/2023] [Indexed: 05/05/2023] Open
Abstract
Adult autologous human epidermal stem cells can be extensively expanded ex vivo for cell and gene therapy. Identifying the mechanisms involved in stem cell maintenance and defining culture conditions to maintain stemness is critical, because an inadequate environment can result in the rapid conversion of stem cells into progenitors/transient amplifying cells (clonal conversion), with deleterious consequences on the quality of the transplants and their ability to engraft. Here, we demonstrate that cultured human epidermal stem cells respond to a small drop in temperature through thermoTRP channels via mTOR signaling. Exposure of cells to rapamycin or a small drop in temperature induces the nuclear translocation of mTOR with an impact on gene expression. We also demonstrate by single-cell analysis that long-term inhibition of mTORC1 reduces clonal conversion and favors the maintenance of stemness. Taken together, our results demonstrate that human keratinocyte stem cells can adapt to environmental changes (e.g., small variations in temperature) through mTOR signaling and constant inhibition of mTORC1 favors stem cell maintenance, a finding of high importance for regenerative medicine applications.
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Affiliation(s)
- Daisuke Nanba
- Laboratory of Stem Cell Dynamics, School of Life Sciences, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
- Department of Experimental Surgery, Lausanne University Hospital, Lausanne, Switzerland
- Division of Aging and Regeneration, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan
| | - Jun-Ichi Sakabe
- Duke-NUS Medical School, Singapore City, Singapore
- Department of Plastic, Reconstructive and Aesthetic Surgery, Singapore General Hospital and A*STAR Skin Research Labs, Singapore City, Singapore
| | - Johannes Mosig
- Laboratory of Stem Cell Dynamics, School of Life Sciences, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
- Department of Experimental Surgery, Lausanne University Hospital, Lausanne, Switzerland
| | - Michel Brouard
- Laboratory of Stem Cell Dynamics, School of Life Sciences, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
- Department of Experimental Surgery, Lausanne University Hospital, Lausanne, Switzerland
| | - Fujio Toki
- Laboratory of Stem Cell Dynamics, School of Life Sciences, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
- Department of Experimental Surgery, Lausanne University Hospital, Lausanne, Switzerland
- Division of Aging and Regeneration, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan
| | - Mariko Shimokawa
- Division of Aging and Regeneration, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan
| | - Mako Kamiya
- Department of Pathology and Immunology, University of Geneva, Geneva, Switzerland
| | - Thomas Braschler
- Laboratory of Stem Cell Dynamics, School of Life Sciences, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
- Department of Experimental Surgery, Lausanne University Hospital, Lausanne, Switzerland
- Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Fahd Azzabi
- Laboratory of Stem Cell Dynamics, School of Life Sciences, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
- Department of Experimental Surgery, Lausanne University Hospital, Lausanne, Switzerland
| | - Stéphanie Droz-Georget Lathion
- Laboratory of Stem Cell Dynamics, School of Life Sciences, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
- Department of Experimental Surgery, Lausanne University Hospital, Lausanne, Switzerland
| | - Kai Johnsson
- Department of Pathology and Immunology, University of Geneva, Geneva, Switzerland
| | - Keya Roy
- Duke-NUS Medical School, Singapore City, Singapore
- Department of Plastic, Reconstructive and Aesthetic Surgery, Singapore General Hospital and A*STAR Skin Research Labs, Singapore City, Singapore
| | - Christoph D Schmid
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Jean-Baptiste Bureau
- Laboratory of Stem Cell Dynamics, School of Life Sciences, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
- Department of Experimental Surgery, Lausanne University Hospital, Lausanne, Switzerland
| | - Ariane Rochat
- Laboratory of Stem Cell Dynamics, School of Life Sciences, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
- Department of Experimental Surgery, Lausanne University Hospital, Lausanne, Switzerland
| | - Yann Barrandon
- Laboratory of Stem Cell Dynamics, School of Life Sciences, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
- Department of Experimental Surgery, Lausanne University Hospital, Lausanne, Switzerland
- Duke-NUS Medical School, Singapore City, Singapore
- Department of Plastic, Reconstructive and Aesthetic Surgery, Singapore General Hospital and A*STAR Skin Research Labs, Singapore City, Singapore
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Chantaravisoot N, Wongkongkathep P, Kalpongnukul N, Pacharakullanon N, Kaewsapsak P, Ariyachet C, Loo JA, Tamanoi F, Pisitkun T. mTORC2 interactome and localization determine aggressiveness of high-grade glioma cells through association with gelsolin. Sci Rep 2023; 13:7037. [PMID: 37120454 PMCID: PMC10148843 DOI: 10.1038/s41598-023-33872-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Accepted: 04/20/2023] [Indexed: 05/01/2023] Open
Abstract
mTOR complex 2 (mTORC2) has been implicated as a key regulator of glioblastoma cell migration. However, the roles of mTORC2 in the migrational control process have not been entirely elucidated. Here, we elaborate that active mTORC2 is crucial for GBM cell motility. Inhibition of mTORC2 impaired cell movement and negatively affected microfilament and microtubule functions. We also aimed to characterize important players involved in the regulation of cell migration and other mTORC2-mediated cellular processes in GBM cells. Therefore, we quantitatively characterized the alteration of the mTORC2 interactome under selective conditions using affinity purification-mass spectrometry in glioblastoma. We demonstrated that changes in cell migration ability specifically altered mTORC2-associated proteins. GSN was identified as one of the most dynamic proteins. The mTORC2-GSN linkage was mostly highlighted in high-grade glioma cells, connecting functional mTORC2 to multiple proteins responsible for directional cell movement in GBM. Loss of GSN disconnected mTORC2 from numerous cytoskeletal proteins and affected the membrane localization of mTORC2. In addition, we reported 86 stable mTORC2-interacting proteins involved in diverse molecular functions, predominantly cytoskeletal remodeling, in GBM. Our findings might help expand future opportunities for predicting the highly migratory phenotype of brain cancers in clinical investigations.
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Affiliation(s)
- Naphat Chantaravisoot
- Department of Biochemistry, Faculty of Medicine, Chulalongkorn University, 1873 Rama IV Pathumwan, Bangkok, 10330, Thailand.
- Center of Excellence in Systems Biology, Faculty of Medicine, Chulalongkorn University, Bangkok, 10330, Thailand.
| | - Piriya Wongkongkathep
- Center of Excellence in Systems Biology, Faculty of Medicine, Chulalongkorn University, Bangkok, 10330, Thailand
- Research Affairs, Faculty of Medicine, Chulalongkorn University, Bangkok, 10330, Thailand
| | - Nuttiya Kalpongnukul
- Center of Excellence in Systems Biology, Faculty of Medicine, Chulalongkorn University, Bangkok, 10330, Thailand
| | - Narawit Pacharakullanon
- Department of Biochemistry, Faculty of Medicine, Chulalongkorn University, 1873 Rama IV Pathumwan, Bangkok, 10330, Thailand
| | - Pornchai Kaewsapsak
- Department of Biochemistry, Faculty of Medicine, Chulalongkorn University, 1873 Rama IV Pathumwan, Bangkok, 10330, Thailand
- Research Unit of Systems Microbiology, Faculty of Medicine, Chulalongkorn University, Bangkok, 10330, Thailand
| | - Chaiyaboot Ariyachet
- Department of Biochemistry, Faculty of Medicine, Chulalongkorn University, 1873 Rama IV Pathumwan, Bangkok, 10330, Thailand
- Center of Excellence in Hepatitis and Liver Cancer, Faculty of Medicine, Chulalongkorn University, Bangkok, 10330, Thailand
| | - Joseph A Loo
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA, 90095, USA
- UCLA/DOE Institute of Genomics and Proteomics, University of California, Los Angeles, CA, 90095, USA
- Department of Biological Chemistry, University of California, Los Angeles, CA, 90095, USA
| | - Fuyuhiko Tamanoi
- Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, CA, 90095, USA
- Institute for Integrated Cell-Material Sciences, Institute for Advanced Study, Kyoto University, Kyoto, 606-8501, Japan
| | - Trairak Pisitkun
- Center of Excellence in Systems Biology, Faculty of Medicine, Chulalongkorn University, Bangkok, 10330, Thailand.
- Research Affairs, Faculty of Medicine, Chulalongkorn University, Bangkok, 10330, Thailand.
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de la Monte SM, Tong M, Delikkaya B. Differential Early Mechanistic Frontal Lobe Responses to Choline Chloride and Soy Isoflavones in an Experimental Model of Fetal Alcohol Spectrum Disorder. Int J Mol Sci 2023; 24:7595. [PMID: 37108779 PMCID: PMC10145811 DOI: 10.3390/ijms24087595] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2023] [Revised: 04/07/2023] [Accepted: 04/18/2023] [Indexed: 04/29/2023] Open
Abstract
Fetal alcohol spectrum disorder (FASD) is the most common preventable cause of neurodevelopmental defects, and white matter is a major target of ethanol neurotoxicity. Therapeutic interventions with choline or dietary soy could potentially supplement public health preventive measures. However, since soy contains abundant choline, it would be important to know if its benefits are mediated by choline or isoflavones. We compared early mechanistic responses to choline and the Daidzein+Genistein (D+G) soy isoflavones in an FASD model using frontal lobe tissue to assess oligodendrocyte function and Akt-mTOR signaling. Long Evans rat pups were binge administered 2 g/Kg of ethanol or saline (control) on postnatal days P3 and P5. P7 frontal lobe slice cultures were treated with vehicle (Veh), Choline chloride (Chol; 75 µM), or D+G (1 µM each) for 72 h without further ethanol exposures. The expression levels of myelin oligodendrocyte proteins and stress-related molecules were measured by duplex enzyme-linked immunosorbent assays (ELISAs), and mTOR signaling proteins and phosphoproteins were assessed using 11-plex magnetic bead-based ELISAs. Ethanol's main short-term effects in Veh-treated cultures were to increase GFAP and relative PTEN phosphorylation and reduce Akt phosphorylation. Chol and D+G significantly modulated the expression of oligodendrocyte myelin proteins and mediators of insulin/IGF-1-Akt-mTOR signaling in both control and ethanol-exposed cultures. In general, the responses were more robust with D+G; the main exception was that RPS6 phosphorylation was significantly increased by Chol and not D+G. The findings suggest that dietary soy, with the benefits of providing complete nutrition together with Choline, could be used to help optimize neurodevelopment in humans at risk for FASD.
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Affiliation(s)
- Suzanne M. de la Monte
- Departments of Pathology and Laboratory Medicine, Medicine, Neurology and Neurosurgery, Rhode Island Hospital, Lifespan Academic Institutions, The Warren Alpert Medical School of Brown University, Providence, RI 02903, USA
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8
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Huang SL, Xie W, Ye YL, Liu J, Qu H, Shen Y, Xu TF, Zhao ZH, Shi Y, Shen JH, Leng Y. Coronarin A modulated hepatic glycogen synthesis and gluconeogenesis via inhibiting mTORC1/S6K1 signaling and ameliorated glucose homeostasis of diabetic mice. Acta Pharmacol Sin 2023; 44:596-609. [PMID: 36085523 PMCID: PMC9958036 DOI: 10.1038/s41401-022-00985-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Accepted: 08/18/2022] [Indexed: 11/09/2022] Open
Abstract
Promotion of hepatic glycogen synthesis and inhibition of hepatic glucose production are effective strategies for controlling hyperglycemia in type 2 diabetes mellitus (T2DM), but agents with both properties were limited. Herein we report coronarin A, a natural compound isolated from rhizomes of Hedychium gardnerianum, which simultaneously stimulates glycogen synthesis and suppresses gluconeogenesis in rat primary hepatocytes. We showed that coronarin A (3, 10 μM) dose-dependently stimulated glycogen synthesis accompanied by increased Akt and GSK3β phosphorylation in rat primary hepatocytes. Pretreatment with Akt inhibitor MK-2206 (2 μM) or PI3K inhibitor LY294002 (10 μM) blocked coronarin A-induced glycogen synthesis. Meanwhile, coronarin A (10 μM) significantly suppressed gluconeogenesis accompanied by increased phosphorylation of MEK, ERK1/2, β-catenin and increased the gene expression of TCF7L2 in rat primary hepatocytes. Pretreatment with β-catenin inhibitor IWR-1-endo (10 μM) or ERK inhibitor SCH772984 (1 μM) abolished the coronarin A-suppressed gluconeogenesis. More importantly, we revealed that coronarin A activated PI3K/Akt/GSK3β and ERK/Wnt/β-catenin signaling via regulation of a key upstream molecule IRS1. Coronarin A (10, 30 μM) decreased the phosphorylation of mTOR and S6K1, the downstream target of mTORC1, which further inhibited the serine phosphorylation of IRS1, and subsequently increased the tyrosine phosphorylation of IRS1. In type 2 diabetic ob/ob mice, chronic administration of coronarin A significantly reduced the non-fasting and fasting blood glucose levels and improved glucose tolerance, accompanied by the inhibited hepatic mTOR/S6K1 signaling and activated IRS1 along with enhanced PI3K/Akt/GSK3β and ERK/Wnt/β-catenin pathways. These results demonstrate the anti-hyperglycemic effect of coronarin A with a novel mechanism by inhibiting mTORC1/S6K1 to increase IRS1 activity, and highlighted coronarin A as a valuable lead compound for the treatment of T2DM.
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Affiliation(s)
- Su-Ling Huang
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
| | - Wei Xie
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yang-Liang Ye
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
| | - Jia Liu
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
| | - Hui Qu
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
| | - Yu Shen
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
| | - Ti-Fei Xu
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
| | - Zhuo-Hui Zhao
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yu Shi
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Jian-Hua Shen
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China.
| | - Ying Leng
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China.
- University of Chinese Academy of Sciences, Beijing, 100049, China.
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9
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Salimi K, Alvandi M, Saberi Pirouz M, Rakhshan K, Howatson G. Regulating eEF2 and eEF2K in skeletal muscle by exercise. Arch Physiol Biochem 2023:1-12. [PMID: 36633938 DOI: 10.1080/13813455.2023.2164898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Revised: 12/15/2022] [Accepted: 12/29/2022] [Indexed: 01/13/2023]
Abstract
Skeletal muscle is a flexible and adaptable tissue that strongly responds to exercise training. The skeletal muscle responds to exercise by increasing muscle protein synthesis (MPS) when energy is available. One of protein synthesis's major rate-limiting and critical regulatory steps is the translation elongation pathway. The process of translation elongation in skeletal muscle is highly regulated. It requires elongation factors that are intensely affected by various physiological stimuli such as exercise and the total available energy of cells. Studies have shown that exercise involves the elongation pathway by numerous signalling pathways. Since the elongation pathway, has been far less studied than the other translation steps, its comprehensive prospect and quantitative understanding remain in the dark. This study highlights the current understanding of the effect of exercise training on the translation elongation pathway focussing on the molecular factors affecting the pathway, including Ca2+, AMPK, PKA, mTORC1/P70S6K, MAPKs, and myostatin. We further discussed the mode and volume of exercise training intervention on the translation elongation pathway.What is the topic of this review? This review summarises the impacts of exercise training on the translation elongation pathway in skeletal muscle focussing on eEF2 and eEF2K.What advances does it highlight? This review highlights mechanisms and factors that profoundly influence the translation elongation pathway and argues that exercise might modulate the response. This review also combines the experimental observations focussing on the regulation of translation elongation during and after exercise. The findings widen our horizon to the notion of mechanisms involved in muscle protein synthesis (MPS) through translation elongation response to exercise training.
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Affiliation(s)
- Kia Salimi
- Department of Exercise Physiology, Faculty of Sport and Exercise Sciences, University of Tehran, Tehran, Iran
| | - Masoomeh Alvandi
- Department of Biological Science in Sport and Health, University of Shahid Beheshti, Tehran, Iran
| | - Mahdi Saberi Pirouz
- Student Research Committee, Iran University of Medical Sciences, Tehran, Iran
| | - Kamran Rakhshan
- Department of Medical Physiology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
- Electrophysiology Research Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Glyn Howatson
- Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, UK
- Water Research Group, North West University, Potchefstroom, South Africa
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10
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de la Monte SM. Malignant Brain Aging: The Formidable Link Between Dysregulated Signaling Through Mechanistic Target of Rapamycin Pathways and Alzheimer's Disease (Type 3 Diabetes). J Alzheimers Dis 2023; 95:1301-1337. [PMID: 37718817 PMCID: PMC10896181 DOI: 10.3233/jad-230555] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/19/2023]
Abstract
Malignant brain aging corresponds to accelerated age-related declines in brain functions eventually derailing the self-sustaining forces that govern independent vitality. Malignant brain aging establishes the path toward dementing neurodegeneration, including Alzheimer's disease (AD). The full spectrum of AD includes progressive dysfunction of neurons, oligodendrocytes, astrocytes, microglia, and the microvascular systems, and is mechanistically driven by insulin and insulin-like growth factor (IGF) deficiencies and resistances with accompanying deficits in energy balance, increased cellular stress, inflammation, and impaired perfusion, mimicking the core features of diabetes mellitus. The underlying pathophysiological derangements result in mitochondrial dysfunction, abnormal protein aggregation, increased oxidative and endoplasmic reticulum stress, aberrant autophagy, and abnormal post-translational modification of proteins, all of which are signature features of both AD and dysregulated insulin/IGF-1-mechanistic target of rapamycin (mTOR) signaling. This article connects the dots from benign to malignant aging to neurodegeneration by reviewing the salient pathologies associated with initially adaptive and later dysfunctional mTOR signaling in the brain. Effective therapeutic and preventive measures must be two-pronged and designed to 1) address complex and shifting impairments in mTOR signaling through the re-purpose of effective anti-diabetes therapeutics that target the brain, and 2) minimize the impact of extrinsic mediators of benign to malignant aging transitions, e.g., inflammatory states, obesity, systemic insulin resistance diseases, and repeated bouts of general anesthesia, by minimizing exposures or implementing neuroprotective measures.
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Affiliation(s)
- Suzanne M. de la Monte
- Departments of Pathology and Laboratory Medicine, Medicine, Neurology and Neurosurgery, Rhode Island Hospital, Lifespan Academic Institutions, and the Warren Alpert Medical School of Brown University, Providence, RI, USA
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11
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Knockdown of miR-372-3p Inhibits the Development of Diabetic Cardiomyopathy by Accelerating Angiogenesis via Activating the PI3K/AKT/mTOR/HIF-1α Signaling Pathway and Suppressing Oxidative Stress. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2022; 2022:4342755. [PMID: 36160704 PMCID: PMC9507772 DOI: 10.1155/2022/4342755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Accepted: 08/10/2022] [Indexed: 11/18/2022]
Abstract
Background DCM is the most common and malignant complication of diabetes. It is characterized by myocardial dilatation, hypertrophy, fibrosis, ventricular remodeling, and contractile dysfunction. Although many studies have demonstrated the function of miRNAs in the progression of DCM, but the specific role of miR-372-3p in DCM remains unknown. Methods C57/BL6J mice were used to construct mouse models of DCM by intraperitoneal injection of STZ (50 mg/kg/d) for 5 consecutive days. Then the mice were randomly divided into model group (intramyocardial injection of empty lentivirus) and miR-372-3p KD group (intramyocardial injection of miR-372-3p KD lentivirus at 109/mouse). Besides, the control group (injection of 0.9% normal saline) was also set up. LY294002, a PI3K inhibitor, was employed in the current study. Western blotting, immunofluorescence staining, quantitative ultrasound method, Masson's trichrome staining, and bioinformatics analysis were performed. Results It was found that miR-372-3p KD significantly improved left ventricular dysfunction and cardiac hypertrophy in DCM mice. Furthermore, it also improved myocardial interstitial fibrosis and remodeling in DCM mice. Immunofluorescence staining and RT-qPCR revealed that miR-372-3p KD might accelerate cardiac remodeling by increasing angiogenesis in DCM mice. Western blotting results revealed that miR-372-3p was an upstream target of the PI3K/AKT-mTOR and HIF-1α signals, as well as NOX2, NOX4, which were responsible for angiogenesis in DCM mice. Besides, the in vitro experiment showed that LY294002 markedly diminished the increased expression levels of p-PI3K, AKT, p-mTOR, p-P70S6K, HIF-1α, NOX2, and NOX4 in the model group and the miR-372-3p KD group, suggesting that PI3K signaling pathway and oxidative stress are involved in miR-372-3p KD-induced angiogenesis in HG-stimulated C166 cells. Conclusions MiR-372-3p KD inhibits the development of DCM via activating the PI3K/AKT/mTOR/HIF-1α signaling pathway or suppressing oxidative stress. This offers an applicable biomarker for DCM treatment.
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12
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Luciano AK, Korobkina E, Lyons SP, Haley JA, Fluharty S, Jung SM, Kettenbach AN, Guertin DA. Proximity labeling of endogenous RICTOR identifies mTOR Complex 2 regulation by ADP ribosylation factor ARF1. J Biol Chem 2022; 298:102379. [PMID: 35973513 PMCID: PMC9513271 DOI: 10.1016/j.jbc.2022.102379] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 07/22/2022] [Accepted: 08/09/2022] [Indexed: 01/08/2023] Open
Abstract
Mechanistic target of rapamycin (mTOR) complex 2 (mTORC2) regulates metabolism, cell proliferation, and cell survival. mTORC2 activity is stimulated by growth factors, and it phosphorylates the hydrophobic motif site of the AGC kinases AKT, SGK, and PKC. However, the proteins that interact with mTORC2 to control its activity and localization remain poorly defined. To identify mTORC2-interacting proteins in living cells, we tagged endogenous RICTOR, an essential mTORC2 subunit, with the modified BirA biotin ligase BioID2 and performed live-cell proximity labeling. We identified 215 RICTOR-proximal proteins, including proteins with known mTORC2 pathway interactions, and 135 proteins (63%) not previously linked to mTORC2 signaling, including nuclear and cytoplasmic proteins. Our imaging and cell fractionation experiments suggest nearly 30% of RICTOR is in the nucleus, hinting at potential nuclear functions. We also identified 29 interactors containing RICTOR-dependent, insulin-stimulated phosphorylation sites, thus providing insight into mTORC2-dependent insulin signaling dynamics. Finally, we identify the endogenous ADP ribosylation factor 1 (ARF1) GTPase as an mTORC2-interacting protein. Through gain-of-function and loss-of-function studies, we provide functional evidence that ARF1 may negatively regulate mTORC2. In summary, we present a new method of studying endogenous mTORC2, a resource of RICTOR/mTORC2 protein interactions in living cells, and a potential mechanism of mTORC2 regulation by the ARF1 GTPase.
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Affiliation(s)
- Amelia K Luciano
- Program in Molecular Medicine, University of Massachusetts Chan Medical School, Worcester, MA 01605
| | - Ekaterina Korobkina
- Program in Molecular Medicine, University of Massachusetts Chan Medical School, Worcester, MA 01605
| | - Scott P Lyons
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755
| | - John A Haley
- Program in Molecular Medicine, University of Massachusetts Chan Medical School, Worcester, MA 01605
| | - Shelagh Fluharty
- Program in Molecular Medicine, University of Massachusetts Chan Medical School, Worcester, MA 01605
| | - Su Myung Jung
- Program in Molecular Medicine, University of Massachusetts Chan Medical School, Worcester, MA 01605
| | - Arminja N Kettenbach
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755; Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth, Hanover, NH 03755
| | - David A Guertin
- Program in Molecular Medicine, University of Massachusetts Chan Medical School, Worcester, MA 01605; Department of Molecular, Cell and Cancer Biology, University of Massachusetts Chan Medical School, Worcester, MA 01605.
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13
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Han Z, Ma K, Tao H, Liu H, Zhang J, Sai X, Li Y, Chi M, Nian Q, Song L, Liu C. A Deep Insight Into Regulatory T Cell Metabolism in Renal Disease: Facts and Perspectives. Front Immunol 2022; 13:826732. [PMID: 35251009 PMCID: PMC8892604 DOI: 10.3389/fimmu.2022.826732] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 01/24/2022] [Indexed: 11/29/2022] Open
Abstract
Kidney disease encompasses a complex set of diseases that can aggravate or start systemic pathophysiological processes through their complex metabolic mechanisms and effects on body homoeostasis. The prevalence of kidney disease has increased dramatically over the last two decades. CD4+CD25+ regulatory T (Treg) cells that express the transcription factor forkhead box protein 3 (Foxp3) are critical for maintaining immune homeostasis and preventing autoimmune disease and tissue damage caused by excessive or unnecessary immune activation, including autoimmune kidney diseases. Recent studies have highlighted the critical role of metabolic reprogramming in controlling the plasticity, stability, and function of Treg cells. They are also likely to play a vital role in limiting kidney transplant rejection and potentially promoting transplant tolerance. Metabolic pathways, such as mitochondrial function, glycolysis, lipid synthesis, glutaminolysis, and mammalian target of rapamycin (mTOR) activation, are involved in the development of renal diseases by modulating the function and proliferation of Treg cells. Targeting metabolic pathways to alter Treg cells can offer a promising method for renal disease therapy. In this review, we provide a new perspective on the role of Treg cell metabolism in renal diseases by presenting the renal microenvironment、relevant metabolites of Treg cell metabolism, and the role of Treg cell metabolism in various kidney diseases.
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Affiliation(s)
- Zhongyu Han
- Department of Nephrology, Sichuan Academy of Medical Science and Sichuan Provincial People's Hospital, Sichuan Renal Disease Clinical Research Center, University of Electronic Science and Technology of China, Chengdu, China.,Chinese Academy of Sciences Sichuan Translational Medicine Research Hospital, Chengdu, China.,Reproductive & Women-Children Hospital, School of Medical and Life Sciences, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Kuai Ma
- Department of Nephrology, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Hongxia Tao
- Reproductive & Women-Children Hospital, School of Medical and Life Sciences, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Hongli Liu
- Reproductive & Women-Children Hospital, School of Medical and Life Sciences, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Jiong Zhang
- Department of Nephrology, Sichuan Academy of Medical Science and Sichuan Provincial People's Hospital, Sichuan Renal Disease Clinical Research Center, University of Electronic Science and Technology of China, Chengdu, China.,Chinese Academy of Sciences Sichuan Translational Medicine Research Hospital, Chengdu, China
| | - Xiyalatu Sai
- Affiliated Hospital of Inner Mongolia University for the Nationalities, Tongliao, China
| | - Yunlong Li
- Reproductive & Women-Children Hospital, School of Medical and Life Sciences, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Mingxuan Chi
- Department of Nephrology, Sichuan Academy of Medical Science and Sichuan Provincial People's Hospital, Sichuan Renal Disease Clinical Research Center, University of Electronic Science and Technology of China, Chengdu, China.,Chinese Academy of Sciences Sichuan Translational Medicine Research Hospital, Chengdu, China
| | - Qing Nian
- Chinese Academy of Sciences Sichuan Translational Medicine Research Hospital, Chengdu, China.,Department of Blood Transfusion Sicuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, China
| | - Linjiang Song
- Reproductive & Women-Children Hospital, School of Medical and Life Sciences, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Chi Liu
- Department of Nephrology, Sichuan Academy of Medical Science and Sichuan Provincial People's Hospital, Sichuan Renal Disease Clinical Research Center, University of Electronic Science and Technology of China, Chengdu, China.,Chinese Academy of Sciences Sichuan Translational Medicine Research Hospital, Chengdu, China
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14
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Soliman GA, Schooling CM. Insulin Receptor Genetic Variants Causal Association with Type 2 Diabetes: A Mendelian Randomization Study. Curr Dev Nutr 2022; 6:nzac044. [PMID: 35611355 PMCID: PMC9121804 DOI: 10.1093/cdn/nzac044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 02/18/2022] [Accepted: 03/23/2022] [Indexed: 11/26/2022] Open
Abstract
Background Type 2 diabetes (T2D) is a prevalent chronic disease associated with several comorbidities. Objectives This study investigated whether the risk of T2D varied with genetically predicted insulin (INS), insulin receptor (INS-R), or insulin-like growth factor 1 receptor (IGF-1R) using genetic variants in a Mendelian randomization (MR) study. Methods A 2-sample MR study was conducted using summary statistics from 2 genome-wide association studies (GWASs). Genetic predictors of the exposures (INS, INS-R, and IGF-1R) were obtained from a publicly available proteomics GWAS of the INTERVAL randomized controlled trial of blood donation in the United Kingdom. For T2D, the study leveraged the DIAbetes Meta-ANalysis of Trans-Ethnic association studies (DIAMANTE) consortium. The estimated associations of INS, INS-R, and IGF-1R proteins with T2D were based on independent single nucleotide polymorphisms (SNPs) strongly (P < 5 × 10-6) predicting each exposure. These SNPs were applied to publicly available genetic associations with T2D from the DIAMANTE case (n = 74,124) and control (n = 824,006) study of people of European descent. SNP-specific Wald estimates were meta-analyzed using inverse variance weighting with multiplicative random effects. Sensitivity analysis was conducted using the weighted median (WM) and MR-Egger. Results INS-R (based on 13 SNPs) was associated with a lower risk of T2D (OR: 0.95 per effect size; 95% CI: 0.92, 0.98; P = 0.001), with similar estimates from the WM and MR-Egger. Insulin (8 SNPs) and IGF-1R (10 SNPs) were not associated with T2D. However, 1 of the SNPs for INS-R was from the ABO blood group gene. Conclusions This study is consistent with a causally protective association of the INS-R with T2D. INS-R in RBCs regulates glycolysis and thus may affect their functionality and integrity. However, a pleiotropic effect via the blood group ABO gene cannot be excluded. The INS-R may be a target for intervention by repurposing existing therapeutics or otherwise to reduce the risk of T2D.
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Affiliation(s)
- Ghada A Soliman
- Department of Environmental, Occupational, and Geospatial Health Sciences, The City University of New York, Graduate School of Public Health, and Health Policy, New York, NY, USA
| | - C Mary Schooling
- Department of Environmental, Occupational, and Geospatial Health Sciences, The City University of New York, Graduate School of Public Health, and Health Policy, New York, NY, USA
- School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
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15
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Cardiovascular protection associated with cilostazol, colchicine and target of rapamycin inhibitors. J Cardiovasc Pharmacol 2022; 80:31-43. [PMID: 35384911 DOI: 10.1097/fjc.0000000000001276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 03/06/2022] [Indexed: 11/26/2022]
Abstract
ABSTRACT An alteration in extracellular matrix production by vascular smooth muscle cells is a crucial event in the pathogenesis of vascular diseases such as aging-related, atherosclerosis and allograft vasculopathy. The human target of rapamycin (TOR) is involved in the synthesis of extracellular matrix by vascular smooth muscle cells. TOR inhibitors reduce arterial stiffness, blood pressure, and left ventricle hypertrophy and decrease cardiovascular risk in kidney graft recipients and patients with coronary artery disease and heart allograft vasculopathy. Other drugs that modulate extracellular matrix production such as cilostazol and colchicine have also demonstrated a beneficial cardiovascular effect. Clinical studies have consistently shown that cilostazol confers cardiovascular protection in peripheral vascular disease, coronary artery disease, and cerebrovascular disease. In patients with type 2 diabetes, cilostazol prevents the progression of subclinical coronary atherosclerosis. Colchicine reduces arterial stiffness in patients with Familial Mediterranean Fever and patients with coronary artery disease. Pathophysiological mechanisms underlying the cardioprotective effect of these drugs may be related to interactions between the cytoskeleton, TOR signaling and cyclic AMP synthesis that remain to be fully elucidated. Adult vascular smooth muscle cells exhibit a contractile phenotype and produce little extracellular matrix. Conditions that upregulate extracellular matrix synthesis induce a phenotypic switch toward a synthetic phenotype. TOR inhibition with rapamycin reduces extracellular matrix production by promoting the change to the contractile phenotype. Cilostazol increases the cytosolic level of cyclic AMP, which in turn leads to a reduction in extracellular matrix synthesis. Colchicine is a microtubule-destabilizing agent that may enhance the synthesis of cyclic AMP.
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16
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Activation of Rictor/mTORC2 signaling acts as a pivotal strategy to protect against sensorineural hearing loss. Proc Natl Acad Sci U S A 2022; 119:e2107357119. [PMID: 35238644 PMCID: PMC8917383 DOI: 10.1073/pnas.2107357119] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Significance The mechanistic target of rapamycin (mTOR) plays a central role in growth, metabolism, and aging. It is assembled into two multiprotein complexes, namely, mTORC1 and mTORC2. We previously demonstrated the efficacy of sirolimus in ARHL in mice by decreasing mTORC1. However, the aspect of mTORC2 regulation in the cochlea is poorly characterized. Herein, based on pharmacological and genetic interventions, we found that a high dose of sirolimus resulted in severe hearing loss by reducing the mTORC2/AKT signaling pathway in the cochlea. Furthermore, selective activation of mTORC2 could protect against hearing loss induced by acoustic trauma and cisplatin-induced ototoxicity. Hence, the therapeutic activation of mTORC2 in conjunction with decreasing mTORC1 might represent a promising and effective strategy in preventing hearing loss.
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17
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Bishnupuri KS, Sainathan SK, Ciorba MA, Houchen CW, Dieckgraefe BK. Reg4 Interacts with CD44 to Regulate Proliferation and Stemness of Colorectal and Pancreatic Cancer Cells. Mol Cancer Res 2022; 20:387-399. [PMID: 34753802 DOI: 10.1158/1541-7786.mcr-21-0224] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 09/08/2021] [Accepted: 11/01/2021] [Indexed: 11/16/2022]
Abstract
Regenerating Gene 4 (Reg4) is highly upregulated in gastrointestinal (GI) malignancies including colorectal and pancreatic cancers. Numerous studies demonstrated an association between higher Reg4 expression and tumor aggressiveness, intrinsic resistance to apoptotic death, and poor outcomes from GI malignancies. However, the precise receptor and underlying signaling mechanism have remained unknown. Although we previously reported a Reg4-mediated induction of EGFR activity in colorectal cancer cells, a direct interaction between Reg4 and EGFR was not observed. This study is focused on identifying the cell surface binding partner of Reg4 and dissecting its role in colorectal cancer and pancreatic cancer growth and stem cell survival. In vitro models of human colorectal cancer and pancreatic cancer were used to evaluate the results. Results of this study find: (i) Reg4 interacts with CD44, a transmembrane protein expressed by a population of colorectal cancer and pancreatic cancer cells; (ii) Reg4 activates regulated intramembrane proteolysis of CD44 resulting in γ-secretase-mediated cleavage and release of the CD44 intracytoplasmic domain (CD44ICD) that functions as a transcriptional activator of D-type cyclins involved in the regulation of cancer cell proliferation and Klf4 and Sox2 expression involved in regulating pluripotency of cancer stem cells; and (iii) Reg4 significantly increases colorectal cancer and pancreatic cancer cell proliferation and their clonogenic potential in stem cell assays. IMPLICATIONS These results suggest that pro-proliferative and pro-stemness effects of Reg4 are mediated through γ-secretase-mediated CD44/CD44ICD signaling, hence strategies to disrupt Reg4-CD44-γ-secretase-CD44ICD signaling axis may increase cancer cell susceptibility to chemo- and radiotherapeutics.
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Affiliation(s)
- Kumar S Bishnupuri
- Division of Gastroenterology, Washington University School of Medicine, St Louis, Missouri
- Veteran Affair St Louis Health Care System, St Louis, Missouri
| | - Satheesh K Sainathan
- Division of Gastroenterology, Washington University School of Medicine, St Louis, Missouri
| | - Matthew A Ciorba
- Division of Gastroenterology, Washington University School of Medicine, St Louis, Missouri
| | - Courtney W Houchen
- Section of Digestive Disease and Nutrition, University of Oklahoma Health Science Center, Oklahoma City, Oklahoma
| | - Brian K Dieckgraefe
- Division of Gastroenterology, Washington University School of Medicine, St Louis, Missouri
- Veteran Affair St Louis Health Care System, St Louis, Missouri
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18
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Tong J, Fang J, Zhu T, Xiang P, Shang J, Chen L, Zhao J, Wang Y, Tong L, Sun M. Pentagalloylglucose reduces AGE-induced inflammation by activating Nrf2/HO-1 and inhibiting the JAK2/STAT3 pathway in mesangial cells. J Pharmacol Sci 2021; 147:305-314. [PMID: 34663512 DOI: 10.1016/j.jphs.2021.08.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 08/11/2021] [Accepted: 08/16/2021] [Indexed: 01/18/2023] Open
Abstract
Pentagalloylglucose (PGG), a gallotannin polyphenolic compound, has been found to possess a host of beneficial pharmacologic activities, such as anti-inflammatory and antioxidative activities. We previously demonstrated that PGG is capable of binding to the cell membrane of renal mesangial cells, but the pharmacological effect of PGG on diabetic renal injury and the underlying mechanisms are still not yet clear. In this study, the effects of PGG on Nrf2/HO-1 and JAK2/STAT3 signaling were explored in AGE-stimulated mesangial cells. Furthermore, the Nrf2 transcriptional inhibitor ML385 was used to verify the involvement of Nrf2 in the PGG-mediated inhibition of the JAK2/STAT3 cascade. Our results showed that PGG significantly inhibited AGE-induced ROS generation and activated AGE-inhibited Nrf2/HO-1 signaling. Moreover, AGE-induced inflammatory cytokines (IL-1β and TNF-α) and their signaling through JAK2/STAT3 were blocked by PGG. Furthermore, ML385 suppressed Nrf2/HO-1 signaling, elevated ROS and cytokine production, and activated JAK2/STAT3 cascade were reversed by PGG. These findings indicate that PGG inhibits the JAK2/STAT3 cascade by activating Nrf2/HO-1 signaling.
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Affiliation(s)
- Jinzhi Tong
- Anhui Provincial Key Laboratory of R&D of Chinese Material Medica, School of Life Science, Anhui University, Hefei, Anhui, China
| | - Jian Fang
- Anhui Provincial Key Laboratory of R&D of Chinese Material Medica, School of Life Science, Anhui University, Hefei, Anhui, China
| | - Tiantian Zhu
- Anhui Provincial Key Laboratory of R&D of Chinese Material Medica, School of Life Science, Anhui University, Hefei, Anhui, China
| | - Pan Xiang
- Anhui Provincial Key Laboratory of R&D of Chinese Material Medica, School of Life Science, Anhui University, Hefei, Anhui, China
| | - Jiaojiao Shang
- Anhui Provincial Key Laboratory of R&D of Chinese Material Medica, School of Life Science, Anhui University, Hefei, Anhui, China
| | - Lei Chen
- Anhui Provincial Key Laboratory of R&D of Chinese Material Medica, School of Life Science, Anhui University, Hefei, Anhui, China
| | - Jindong Zhao
- The First Affiliated Hospital of Anhui University of TCM, Hefei, Anhui, China
| | - Yanxin Wang
- The First Affiliated Hospital of Anhui University of TCM, Hefei, Anhui, China
| | - Li Tong
- Qinghai Provincial Key Laboratory of Traditional Chinese Medicine Research for Glucolipid Metabolic Diseases, Medical College of Qinghai University, Xining, Qinghai, China
| | - Min Sun
- Anhui Provincial Key Laboratory of R&D of Chinese Material Medica, School of Life Science, Anhui University, Hefei, Anhui, China.
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Gatti G, Vilardo L, Musa C, Di Pietro C, Bonaventura F, Scavizzi F, Torcinaro A, Bucci B, Saporito R, Arisi I, De Santa F, Raspa M, Guglielmi L, D’Agnano I. Role of Lamin A/C as Candidate Biomarker of Aggressiveness and Tumorigenicity in Glioblastoma Multiforme. Biomedicines 2021; 9:biomedicines9101343. [PMID: 34680461 PMCID: PMC8533312 DOI: 10.3390/biomedicines9101343] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Revised: 09/21/2021] [Accepted: 09/24/2021] [Indexed: 12/11/2022] Open
Abstract
Nuclear lamina components have long been regarded as scaffolding proteins, forming a dense fibrillar structure necessary for the maintenance of the nucleus shape in all the animal kingdom. More recently, mutations, aberrant localisation and deregulation of these proteins have been linked to several diseases, including cancer. Using publicly available data we found that the increased expression levels of the nuclear protein Lamin A/C correlate with a reduced overall survival in The Cancer Genome Atlas Research Network (TCGA) patients affected by glioblastoma multiforme (GBM). We show that the expression of the LMNA gene is linked to the enrichment of cancer-related pathways, particularly pathways related to cell adhesion and cell migration. Mimicking the modulation of LMNA in a GBM preclinical cancer model, we confirmed both in vitro and in vivo that the increased expression of LMNA is associated with an increased aggressiveness and tumorigenicity. In addition, delving into the possible mechanism behind LMNA-induced GBM aggressiveness and tumorigenicity, we found that the mTORC2 component, Rictor, plays a central role in mediating these effects.
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Affiliation(s)
- Giuliana Gatti
- Department of Biotechnology and Translational Medicine, University of Milan, 20129 Milan, Italy;
| | - Laura Vilardo
- Institute for Biomedical Technologies (ITB), CNR, 20054 Segrate, Italy; (L.V.); (C.M.)
| | - Carla Musa
- Institute for Biomedical Technologies (ITB), CNR, 20054 Segrate, Italy; (L.V.); (C.M.)
| | - Chiara Di Pietro
- Institute of Biochemistry and Cell Biology (IBBC), CNR, 00015 Monterotondo, Italy; (C.D.P.); (F.B.); (F.S.); (A.T.); (F.D.S.); (M.R.)
| | - Fabrizio Bonaventura
- Institute of Biochemistry and Cell Biology (IBBC), CNR, 00015 Monterotondo, Italy; (C.D.P.); (F.B.); (F.S.); (A.T.); (F.D.S.); (M.R.)
| | - Ferdinando Scavizzi
- Institute of Biochemistry and Cell Biology (IBBC), CNR, 00015 Monterotondo, Italy; (C.D.P.); (F.B.); (F.S.); (A.T.); (F.D.S.); (M.R.)
| | - Alessio Torcinaro
- Institute of Biochemistry and Cell Biology (IBBC), CNR, 00015 Monterotondo, Italy; (C.D.P.); (F.B.); (F.S.); (A.T.); (F.D.S.); (M.R.)
| | - Barbara Bucci
- UOC Clinical Pathology, San Pietro Hospital FBF, 00189 Rome, Italy; (B.B.); (R.S.)
| | - Raffaele Saporito
- UOC Clinical Pathology, San Pietro Hospital FBF, 00189 Rome, Italy; (B.B.); (R.S.)
| | - Ivan Arisi
- Bioinformatics Facility, European Brain Research Institute (EBRI) “Rita Levi Montalcini”, 00161 Rome, Italy;
| | - Francesca De Santa
- Institute of Biochemistry and Cell Biology (IBBC), CNR, 00015 Monterotondo, Italy; (C.D.P.); (F.B.); (F.S.); (A.T.); (F.D.S.); (M.R.)
| | - Marcello Raspa
- Institute of Biochemistry and Cell Biology (IBBC), CNR, 00015 Monterotondo, Italy; (C.D.P.); (F.B.); (F.S.); (A.T.); (F.D.S.); (M.R.)
| | - Loredana Guglielmi
- Institute for Biomedical Technologies (ITB), CNR, 20054 Segrate, Italy; (L.V.); (C.M.)
- Correspondence: (L.G.); (I.D.)
| | - Igea D’Agnano
- Institute for Biomedical Technologies (ITB), CNR, 20054 Segrate, Italy; (L.V.); (C.M.)
- Correspondence: (L.G.); (I.D.)
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Phosphorylation of RCC1 on Serine 11 Facilitates G1/S Transition in HPV E7-Expressing Cells. Biomolecules 2021; 11:biom11070995. [PMID: 34356619 PMCID: PMC8301946 DOI: 10.3390/biom11070995] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Revised: 07/01/2021] [Accepted: 07/01/2021] [Indexed: 11/25/2022] Open
Abstract
Persistent infection of high-risk human papillomavirus (HR-HPV) plays a causal role in cervical cancer. Regulator of chromosome condensation 1 (RCC1) is a critical cell cycle regulator, which undergoes a few post-translational modifications including phosphorylation. Here, we showed that serine 11 (S11) of RCC1 was phosphorylated in HPV E7-expressing cells. However, S11 phosphorylation was not up-regulated by CDK1 in E7-expressing cells; instead, the PI3K/AKT/mTOR pathway promoted S11 phosphorylation. Knockdown of AKT or inhibition of the PI3K/AKT/mTOR pathway down-regulated phosphorylation of RCC1 S11. Furthermore, S11 phosphorylation occurred throughout the cell cycle, and reached its peak during the mitosis phase. Our previous data proved that RCC1 was necessary for the G1/S cell cycle progression, and in the present study we showed that the RCC1 mutant, in which S11 was mutated to alanine (S11A) to mimic non-phosphorylation status, lost the ability to facilitate G1/S transition in E7-expressing cells. Moreover, RCC1 S11 was phosphorylated by the PI3K/AKT/mTOR pathway in HPV-positive cervical cancer SiHa and HeLa cells. We conclude that S11 of RCC1 is phosphorylated by the PI3K/AKT/mTOR pathway and phosphorylation of RCC1 S11 facilitates the abrogation of G1 checkpoint in HPV E7-expressing cells. In short, our study explores a new role of RCC1 S11 phosphorylation in cell cycle regulation.
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The effects of glucagon and the target of rapamycin (TOR) on skeletal muscle protein synthesis and age-dependent sarcopenia in humans. Clin Nutr ESPEN 2021; 44:15-25. [PMID: 34330459 DOI: 10.1016/j.clnesp.2021.06.025] [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: 06/16/2021] [Accepted: 06/21/2021] [Indexed: 01/07/2023]
Abstract
BACKGROUND AND AIMS Human target of rapamycin (TOR) is a kinase that stimulates protein synthesis in the skeletal muscle in response to amino acids and physical activity. METHODS A comprehensive literature search was conducted on the PubMed database from its inception up to May 2021 to retrieve information on the effects of TOR and glucagon on muscle function. Articles written in English regarding human subjects were included. RESULTS l-leucine activates TOR to initiate protein synthesis in the skeletal muscle. Glucagon has a crucial role suppressing skeletal muscle protein synthesis by increasing l-leucine oxidation and the irreversible loss of this amino acid. Glucagon-induced l-leucine oxidation suppresses TOR and attenuates the ability of skeletal muscle to synthesize proteins. Conditions associated with increased glucagon secretion typically feature reduced ability to synthesize proteins in the skeletal muscle that may evolve into sarcopenia. Animal protein ingestion, unlike vegetable protein, stimulates glucagon secretion. High intake of animal protein increases l-leucine oxidation and promotes the use of amino acids as fuel. Sarcopenia and arterial stiffness characteristically occur together in conditions featuring insulin resistance, such as aging. Insulin resistance mediates the relationship between aging and sarcopenia and arterial stiffness. The loss of skeletal muscle fibers that characterizes sarcopenia is followed by collagen and lipid accumulation. Likewise, insulin resistance is associated with arterial stiffness and intima-media thickening due to adaptive accretion of collagen and lipids in the arterial wall. CONCLUSIONS Human TOR participates in the pathogenesis of sarcopenia and arterial stiffness, although its effects remain to be fully elucidated.
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mTOR Driven Gene Transcription Is Required for Cholesterol Production in Neurons of the Developing Cerebral Cortex. Int J Mol Sci 2021; 22:ijms22116034. [PMID: 34204880 PMCID: PMC8199781 DOI: 10.3390/ijms22116034] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Revised: 05/15/2021] [Accepted: 05/28/2021] [Indexed: 12/13/2022] Open
Abstract
Dysregulated mammalian target of rapamycin (mTOR) activity is associated with various neurodevelopmental disorders ranging from idiopathic autism spectrum disorders (ASD) to syndromes caused by single gene defects. This suggests that maintaining mTOR activity levels in a physiological range is essential for brain development and functioning. Upon activation, mTOR regulates a variety of cellular processes such as cell growth, autophagy, and metabolism. On a molecular level, however, the consequences of mTOR activation in the brain are not well understood. Low levels of cholesterol are associated with a wide variety of neurodevelopmental disorders. We here describe numerous genes of the sterol/cholesterol biosynthesis pathway to be transcriptionally regulated by mTOR complex 1 (mTORC1) signaling in vitro in primary neurons and in vivo in the developing cerebral cortex of the mouse. We find that these genes are shared targets of the transcription factors SREBP, SP1, and NF-Y. Prenatal as well as postnatal mTORC1 inhibition downregulated expression of these genes which directly translated into reduced cholesterol levels, pointing towards a substantial metabolic function of the mTORC1 signaling cascade. Altogether, our results indicate that mTORC1 is an essential transcriptional regulator of the expression of sterol/cholesterol biosynthesis genes in the developing brain. Altered expression of these genes may be an important factor contributing to the pathogenesis of neurodevelopmental disorders associated with dysregulated mTOR signaling.
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Mazloumi Gavgani F, Karlsson T, Tangen IL, Morovicz AP, Arnesen VS, Turcu DC, Ninzima S, Spang K, Krakstad C, Guillermet-Guibert J, Lewis AE. Nuclear upregulation of class I phosphoinositide 3-kinase p110β correlates with high 47S rRNA levels in cancer cells. J Cell Sci 2021; 134:jcs.246090. [PMID: 33536247 DOI: 10.1242/jcs.246090] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Accepted: 12/24/2020] [Indexed: 12/12/2022] Open
Abstract
The class I phosphoinositide 3-kinase (PI3K) catalytic subunits p110α and p110β are ubiquitously expressed but differently targeted in tumours. In cancer, PIK3CB (encoding p110β) is seldom mutated compared with PIK3CA (encoding p110α) but can contribute to tumorigenesis in certain PTEN-deficient tumours. The underlying molecular mechanisms are, however, unclear. We have previously reported that p110β is highly expressed in endometrial cancer (EC) cell lines and at the mRNA level in primary patient tumours. Here, we show that p110β protein levels are high in both the cytoplasmic and nuclear compartments in EC cells. Moreover, high nuclear:cytoplasmic staining ratios were detected in high-grade primary tumours. High levels of phosphatidylinositol (3,4,5)-trisphosphate [PtdIns(3,4,5)P 3] were measured in the nucleus of EC cells, and pharmacological and genetic approaches showed that its production was partly dependent upon p110β activity. Using immunofluorescence staining, p110β and PtdIns(3,4,5)P 3 were localised in the nucleolus, which correlated with high levels of 47S pre-rRNA. p110β inhibition led to a decrease in both 47S rRNA levels and cell proliferation. In conclusion, these results present a nucleolar role for p110β that may contribute to tumorigenesis in EC.This article has an associated First Person interview with Fatemeh Mazloumi Gavgani, joint first author of the paper.
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Affiliation(s)
| | - Thomas Karlsson
- Department of Biological Sciences, University of Bergen, Bergen 5008, Norway
| | - Ingvild L Tangen
- Centre for Cancer Biomarkers, Department of Clinical Science, University of Bergen, Bergen 5021, Norway.,Department of Gynaecology and Obstetrics, Haukeland University Hospital, Bergen 5021, Norway
| | | | | | - Diana C Turcu
- Department of Biological Sciences, University of Bergen, Bergen 5008, Norway
| | - Sandra Ninzima
- Department of Biological Sciences, University of Bergen, Bergen 5008, Norway
| | - Katharina Spang
- Department of Biological Sciences, University of Bergen, Bergen 5008, Norway
| | - Camilla Krakstad
- Centre for Cancer Biomarkers, Department of Clinical Science, University of Bergen, Bergen 5021, Norway.,Department of Gynaecology and Obstetrics, Haukeland University Hospital, Bergen 5021, Norway
| | - Julie Guillermet-Guibert
- Inserm U1037, Centre de Recherches en Cancérologie de Toulouse (CRCT), Institut National de la Santé et de la Recherche Médicale (INSERM), Université Toulouse III Paul Sabatier, 31037 Toulouse, France
| | - Aurélia E Lewis
- Department of Biological Sciences, University of Bergen, Bergen 5008, Norway
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Leastro MO, Freitas-Astúa J, Kitajima EW, Pallás V, Sánchez-Navarro JA. Unravelling the involvement of cilevirus p32 protein in the viral transport. Sci Rep 2021; 11:2943. [PMID: 33536554 PMCID: PMC7859179 DOI: 10.1038/s41598-021-82453-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Accepted: 01/13/2021] [Indexed: 12/04/2022] Open
Abstract
Citrus leprosis (CL) is a severe disease that affects citrus orchards mainly in Latin America. It is caused by Brevipalpus-transmitted viruses from genera Cilevirus and Dichorhavirus. Currently, no reports have explored the movement machinery for the cilevirus. Here, we have performed a detailed functional study of the p32 movement protein (MP) of two cileviruses. Citrus leprosis-associated viruses are not able to move systemically in neither their natural nor experimental host plants. However, here we show that cilevirus MPs are able to allow the cell-to-cell and long-distance transport of movement-defective alfalfa mosaic virus (AMV). Several features related with the viral transport were explored, including: (i) the ability of cilevirus MPs to facilitate virus movement on a nucleocapsid assembly independent-manner; (ii) the generation of tubular structures from transient expression in protoplast; (iii) the capability of the N- and C- terminus of MP to interact with the cognate capsid protein (p29) and; (iv) the role of the C-terminus of p32 in the cell-to-cell and long-distance transport, tubule formation and the MP-plasmodesmata co-localization. The MP was able to direct the p29 to the plasmodesmata, whereby the C-terminus of MP is independently responsible to recruit the p29 to the cell periphery. Furthermore, we report that MP possess the capacity to enter the nucleolus and to bind to a major nucleolar protein, the fibrillarin. Based on our findings, we provide a model for the role of the p32 in the intra- and intercellular viral spread.
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Affiliation(s)
- Mikhail Oliveira Leastro
- Unidade Laboratorial de Referência em Biologia Molecular Aplicada, Instituto Biológico, São Paulo, SP, Brazil. .,Instituto de Biología Molecular y Celular de Plantas, Universidad Politécnica de Valencia-Consejo Superior de Investigaciones Científicas (CSIC), Valencia, Spain.
| | - Juliana Freitas-Astúa
- Unidade Laboratorial de Referência em Biologia Molecular Aplicada, Instituto Biológico, São Paulo, SP, Brazil.,Embrapa Mandioca e Fruticultura, Cruz das Almas, BA, Brazil
| | - Elliot Watanabe Kitajima
- Departamento de Fitopatologia e Nematologia, Escola Superior de Agricultura Luiz de Queiroz, Universidade de São Paulo, Piracicaba, SP, Brazil
| | - Vicente Pallás
- Instituto de Biología Molecular y Celular de Plantas, Universidad Politécnica de Valencia-Consejo Superior de Investigaciones Científicas (CSIC), Valencia, Spain
| | - Jesús A Sánchez-Navarro
- Instituto de Biología Molecular y Celular de Plantas, Universidad Politécnica de Valencia-Consejo Superior de Investigaciones Científicas (CSIC), Valencia, Spain.
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25
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Maniyadath B, Sandra US, Kolthur-Seetharam U. Metabolic choreography of gene expression: nutrient transactions with the epigenome. J Biosci 2020. [DOI: 10.1007/s12038-019-9987-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Zhou X, Zhong Y, Molinar-Inglis O, Kunkel MT, Chen M, Sun T, Zhang J, Shyy JYJ, Trejo J, Newton AC, Zhang J. Location-specific inhibition of Akt reveals regulation of mTORC1 activity in the nucleus. Nat Commun 2020; 11:6088. [PMID: 33257668 PMCID: PMC7705703 DOI: 10.1038/s41467-020-19937-w] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Accepted: 10/27/2020] [Indexed: 12/13/2022] Open
Abstract
The mechanistic target of rapamycin complex 1 (mTORC1) integrates growth, nutrient and energy status cues to control cell growth and metabolism. While mTORC1 activation at the lysosome is well characterized, it is not clear how this complex is regulated at other subcellular locations. Here, we combine location-selective kinase inhibition, live-cell imaging and biochemical assays to probe the regulation of growth factor-induced mTORC1 activity in the nucleus. Using a nuclear targeted Akt Substrate-based Tandem Occupancy Peptide Sponge (Akt-STOPS) that we developed for specific inhibition of Akt, a critical upstream kinase, we show that growth factor-stimulated nuclear mTORC1 activity requires nuclear Akt activity. Further mechanistic dissection suggests that nuclear Akt activity mediates growth factor-induced nuclear translocation of Raptor, a regulatory scaffolding component in mTORC1, and localization of Raptor to the nucleus results in nuclear mTORC1 activity in the absence of growth factor stimulation. Taken together, these results reveal a mode of regulation of mTORC1 that is distinct from its lysosomal activation, which controls mTORC1 activity in the nuclear compartment.
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Affiliation(s)
- Xin Zhou
- Department of Pharmacology, University of California, San Diego, La Jolla, CA, USA
| | - Yanghao Zhong
- Department of Pharmacology, University of California, San Diego, La Jolla, CA, USA
- Biomedical Sciences Graduate Program, University of California, San Diego, La Jolla, CA, USA
| | | | - Maya T Kunkel
- Department of Pharmacology, University of California, San Diego, La Jolla, CA, USA
| | - Mingyuan Chen
- Department of Bioengineering, University of California, San Diego, La Jolla, CA, USA
| | - Tengqian Sun
- Department of Pharmacology, University of California, San Diego, La Jolla, CA, USA
| | - Jiao Zhang
- Division of Cardiology, Department of Medicine, University of California San Diego, La Jolla, CA, USA
| | - John Y-J Shyy
- Division of Cardiology, Department of Medicine, University of California San Diego, La Jolla, CA, USA
| | - JoAnn Trejo
- Department of Pharmacology, University of California, San Diego, La Jolla, CA, USA
| | - Alexandra C Newton
- Department of Pharmacology, University of California, San Diego, La Jolla, CA, USA
| | - Jin Zhang
- Department of Pharmacology, University of California, San Diego, La Jolla, CA, USA.
- Department of Bioengineering, University of California, San Diego, La Jolla, CA, USA.
- Department of Chemistry & Biochemistry, University of California, San Diego, La Jolla, CA, USA.
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mTOR-targeted cancer therapy: great target but disappointing clinical outcomes, why? Front Med 2020; 15:221-231. [PMID: 33165737 DOI: 10.1007/s11684-020-0812-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Accepted: 06/12/2020] [Indexed: 02/07/2023]
Abstract
The mammalian target of rapamycin (mTOR) critically regulates several essential biological functions, such as cell growth, metabolism, survival, and immune response by forming two important complexes, namely, mTOR complex 1 (mTORC1) and complex 2 (mTORC2). mTOR signaling is often dysregulated in cancers and has been considered an attractive cancer therapeutic target. Great efforts have been made to develop efficacious mTOR inhibitors, particularly mTOR kinase inhibitors, which suppress mTORC1 and mTORC2; however, major success has not been achieved. With the strong scientific rationale, the intriguing question is why cancers are insensitive or not responsive to mTOR-targeted cancer therapy in clinics. Beyond early findings on induced activation of PI3K/Akt, MEK/ERK, and Mnk/eIF4E survival signaling pathways that compromise the efficacy of rapalog-based cancer therapy, recent findings on the essential role of GSK3 in mediating cancer cell response to mTOR inhibitors and mTORC1 inhibition-induced upregulation of PD-L1 in cancer cells may provide some explanations. These new findings may also offer us the opportunity to rationally utilize mTOR inhibitors in cancer therapy. Further elucidation of the biology of complicated mTOR networks may bring us the hope to develop effective therapeutic strategies with mTOR inhibitors against cancer.
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Ucha M, Roura-Martínez D, Ambrosio E, Higuera-Matas A. The role of the mTOR pathway in models of drug-induced reward and the behavioural constituents of addiction. J Psychopharmacol 2020; 34:1176-1199. [PMID: 32854585 DOI: 10.1177/0269881120944159] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
BACKGROUND Exposure to drugs of abuse induces neuroadaptations in critical nodes of the so-called reward systems that are thought to mediate the transition from controlled drug use to the compulsive drug-seeking that characterizes addictive disorders. These neural adaptations are likely to require protein synthesis, which is regulated, among others, by the mechanistic target of the rapamycin kinase (mTOR) signalling cascade. METHODS We have performed a narrative review of the literature available in PubMed about the involvement of the mTOR pathway in drug-reward and addiction-related phenomena. AIMS The aim of this study was to review the underlying architecture of this complex intracellular network and to discuss the alterations of its components that are evident after exposure to drugs of abuse. The aim was also to delineate the effects that manipulations of the mTOR network have on models of drug reward and on paradigms that recapitulate some of the psychological components of addiction. RESULTS There is evidence for the involvement of the mTOR pathway in the acute and rewarding effects of drugs of abuse, especially psychostimulants. However, the data regarding opiates are scarce. There is a need to use sophisticated animal models of addiction to ascertain the real role of the mTOR pathway in this pathology and not just in drug-mediated reward. The involvement of this pathway in behavioural addictions and impulsivity should also be studied in detail in the future. CONCLUSIONS Although there is a plethora of data about the modulation of mTOR by drugs of abuse, the involvement of this signalling pathway in addictive disorders requires further research.
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Affiliation(s)
- Marcos Ucha
- Department of Psychobiology, National University for Distance Learning (UNED), Madrid, Spain
| | - David Roura-Martínez
- Department of Psychobiology, National University for Distance Learning (UNED), Madrid, Spain
| | - Emilio Ambrosio
- Department of Psychobiology, National University for Distance Learning (UNED), Madrid, Spain
| | - Alejandro Higuera-Matas
- Department of Psychobiology, National University for Distance Learning (UNED), Madrid, Spain
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Lv Z, Muheremu A, Bai X, Zou X, Lin T, Chen B. PTH(1‑34) activates the migration and adhesion of BMSCs through the rictor/mTORC2 pathway. Int J Mol Med 2020; 46:2089-2101. [PMID: 33125102 PMCID: PMC7595657 DOI: 10.3892/ijmm.2020.4754] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2020] [Accepted: 07/09/2020] [Indexed: 12/23/2022] Open
Abstract
The ability of intermittent parathyroid hormone (1-34) [PTH(1-34)] treatment to enhance bone-implant osseo-integration was recently demonstrated in vivo. However, the mechanisms through which PTH (1-34) regulates bone marrow-derived stromal cells (BMSCs) remain unclear. The present study thus aimed to investigate the effects of PTH(1-34) on the migration and adhesion of, and rictor/mammalian target of rapamycin complex 2 (mTORC2) signaling in BMSCs. In the present study, BMSCs were isolated from Sprague-Dawley rats treated with various concentrations of PTH(1-34) for different periods of time. PTH(1-34) treatment was performed with or without an mTORC1 inhibitor (20 nM rapamycin) and mTORC1/2 inhibitor (10 µM PP242). Cell migration was assessed by Transwell cell migration assays and wound healing assays. Cell adhesion and related mRNA expression were investigated through adhesion assays and reverse transcription-quantitative polymerase chain reaction (RT-qPCR), respectively. The protein expression of chemokine receptors (CXCR4 and CCR2) and adhesion factors [intercellular adhesion molecule 1 (ICAM-1), fibronectin and integrin β1] was examined by western blot analysis. The results revealed that various concentrations (1, 10, 20, 50 and 100 nM) of PTH(1-34) significantly increased the migration and adhesion of BMSCs, as well as the expression of CXCR4, CCR2, ICAM-1, fibronectin and integrin β1. In addition, the p-Akt and p-S6 levels were also upregulated by PTH(1-34). BMSCs subjected to mTORC1/2 signaling pathway inhibition or rictor silencing exhibited a markedly reduced PTH-induced migration and adhesion, while no such effect was observed for the BMSCs subjected to mTORC1 pathway inhibition or raptor silencing. These results indicate that PTH(1-34) promotes BMSC migration and adhesion through rictor/mTORC2 signaling in vitro. Taken together, the results of the present study reveal an important mechanism for the therapeutic effects of PTH(1-34) on bone-implant osseointegration and suggest a potential treatment strategy based on the effect of PTH(1-34) on BMSCs.
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Affiliation(s)
- Zhong Lv
- Department of Orthopedics, Guangzhou Panyu Central Hospital, Guangzhou, Guangdong 510080, P.R. China
| | | | - Xiaochun Bai
- Guangdong Provincial Key Laboratory of Orthopedics and Traumatology, The First Affiliated Hospital of Sun Yat‑sen University, Guangzhou, Guangdong 510080, P.R. China
| | - Xuenong Zou
- Guangdong Provincial Key Laboratory of Orthopedics and Traumatology, The First Affiliated Hospital of Sun Yat‑sen University, Guangzhou, Guangdong 510080, P.R. China
| | - Tao Lin
- Department of Orthopedics, Zhujiang Hospital of Southern Medical University, Guangzhou, Guangdong 510280, P.R. China
| | - Bailing Chen
- Guangdong Provincial Key Laboratory of Orthopedics and Traumatology, The First Affiliated Hospital of Sun Yat‑sen University, Guangzhou, Guangdong 510080, P.R. China
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Soliman GA, Schooling CM. Causal association between mTOR-dependent EIF-4E and EIF-4A circulating protein levels and type 2 diabetes: a Mendelian randomization study. Sci Rep 2020; 10:15737. [PMID: 32978410 PMCID: PMC7519073 DOI: 10.1038/s41598-020-71987-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2020] [Accepted: 08/19/2020] [Indexed: 12/22/2022] Open
Abstract
The mammalian Target of Rapamycin complex 1 (mTORC1) nutrient-sensing pathway is a central regulator of cell growth and metabolism and is dysregulated in diabetes. The eukaryotic translation initiation factor 4E (EIF-4E) protein, a key regulator of gene translation and protein function, is controlled by mTORC1 and EIF-4E Binding Proteins (EIF4EBPs). Both EIF4EBPs and ribosomal protein S6K kinase (RP-S6K) are downstream effectors regulated by mTORC1 but converge to regulate two independent pathways. We investigated whether the risk of type 2 diabetes varied with genetically predicted EIF-4E, EIF-4A, EIF-4G, EIF4EBP, and RP-S6K circulating levels using Mendelian Randomization. We estimated the causal role of EIF-4F complex, EIF4EBP, and S6K in the circulation on type 2 diabetes, based on independent single nucleotide polymorphisms strongly associated (p = 5 × 10–6) with EIF-4E (16 SNPs), EIF-4A (11 SNPs), EIF-4G (6 SNPs), EIF4EBP2 (12 SNPs), and RP-S6K (16 SNPs). The exposure data were obtained from the INTERVAL study. We applied these SNPs for each exposure to publically available genetic associations with diabetes from the DIAbetes Genetics Replication And Meta-analysis (DIAGRAM) case (n = 26,676) and control (n = 132,532) study (mean age 57.4 years). We meta-analyzed SNP-specific Wald-estimates using inverse variance weighting with multiplicative random effects and conducted sensitivity analysis. Mendelian Randomization (MR-Base) R package was used in the analysis. The PhenoScanner curated database was used to identify disease associations with SNP gene variants. EIF-4E is associated with a lowered risk of type 2 diabetes with an odds ratio (OR) 0.94, 95% confidence interval (0.88, 0.99, p = 0.03) with similar estimates from the weighted median and MR-Egger. Similarly, EIF-4A was associated with lower risk of type 2 diabetes with odds ratio (OR) 0.90, 95% confidence interval (0.85, 0.97, p = 0.0003). Sensitivity analysis using MR-Egger and weighed median analysis does not indicate that there is a pleiotropic effect. This unbiased Mendelian Randomization estimate is consistent with a protective causal association of EIF-4E and EIF-4A on type 2 diabetes. EIF-4E and EIF-4A may be targeted for intervention by repurposing existing therapeutics to reduce the risk of type 2 diabetes.
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Affiliation(s)
- Ghada A Soliman
- Department of Environmental, Occupational and Geospatial Health Sciences, The City University of New York, Graduate School of Public Health and Health Policy, 55 West 125th St, New York, NY, 10027, USA.
| | - C Mary Schooling
- Department of Environmental, Occupational and Geospatial Health Sciences, The City University of New York, Graduate School of Public Health and Health Policy, 55 West 125th St, New York, NY, 10027, USA.,School of Public Health, Li Ka Shing, Faculty of Medicine, The University of Hong Kong, 7 Sassoon Road, Hong Kong, China
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31
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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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Melick CH, Jewell JL. Regulation of mTORC1 by Upstream Stimuli. Genes (Basel) 2020; 11:genes11090989. [PMID: 32854217 PMCID: PMC7565831 DOI: 10.3390/genes11090989] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 08/22/2020] [Accepted: 08/23/2020] [Indexed: 01/08/2023] Open
Abstract
The mammalian target of rapamycin (mTOR) is an evolutionary conserved Ser/Thr protein kinase that senses multiple upstream stimuli to control cell growth, metabolism, and autophagy. mTOR is the catalytic subunit of mTOR complex 1 (mTORC1). A significant amount of research has uncovered the signaling pathways regulated by mTORC1, and the involvement of these signaling cascades in human diseases like cancer, diabetes, and ageing. Here, we review advances in mTORC1 regulation by upstream stimuli. We specifically focus on how growth factors, amino acids, G-protein coupled receptors (GPCRs), phosphorylation, and small GTPases regulate mTORC1 activity and signaling.
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Affiliation(s)
- Chase H. Melick
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA;
- Harold C. Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
- Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Jenna L. Jewell
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA;
- Harold C. Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
- Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
- Correspondence:
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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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35
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Mendik P, Dobronyi L, Hári F, Kerepesi C, Maia-Moço L, Buszlai D, Csermely P, Veres DV. Translocatome: a novel resource for the analysis of protein translocation between cellular organelles. Nucleic Acids Res 2020; 47:D495-D505. [PMID: 30380112 PMCID: PMC6324082 DOI: 10.1093/nar/gky1044] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Accepted: 10/25/2018] [Indexed: 01/02/2023] Open
Abstract
Here we present Translocatome, the first dedicated database of human translocating proteins (URL: http://translocatome.linkgroup.hu). The core of the Translocatome database is the manually curated data set of 213 human translocating proteins listing the source of their experimental validation, several details of their translocation mechanism, their local compartmentalized interactome, as well as their involvement in signalling pathways and disease development. In addition, using the well-established and widely used gradient boosting machine learning tool, XGBoost, Translocatome provides translocation probability values for 13 066 human proteins identifying 1133 and 3268 high- and low-confidence translocating proteins, respectively. The database has user-friendly search options with a UniProt autocomplete quick search and advanced search for proteins filtered by their localization, UniProt identifiers, translocation likelihood or data complexity. Download options of search results, manually curated and predicted translocating protein sets are available on its website. The update of the database is helped by its manual curation framework and connection to the previously published ComPPI compartmentalized protein–protein interaction database (http://comppi.linkgroup.hu). As shown by the application examples of merlin (NF2) and tumor protein 63 (TP63) Translocatome allows a better comprehension of protein translocation as a systems biology phenomenon and can be used as a discovery-tool in the protein translocation field.
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Affiliation(s)
- Péter Mendik
- Department of Medical Chemistry, Semmelweis University, Budapest, Hungary
| | - Levente Dobronyi
- Department of Medical Chemistry, Semmelweis University, Budapest, Hungary
| | - Ferenc Hári
- Department of Medical Chemistry, Semmelweis University, Budapest, Hungary
| | - Csaba Kerepesi
- Institute for Computer Science and Control (MTA SZTAKI), Hungarian Academy of Sciences, Budapest, Hungary.,Institute of Mathematics, Eötvös Loránd University, Budapest, Hungary
| | - Leonardo Maia-Moço
- Department of Medical Chemistry, Semmelweis University, Budapest, Hungary.,Cancer Biology and Epigenetics Group, Research Center of Portuguese Oncology Institute of Porto, Portugal
| | - Donát Buszlai
- Department of Medical Chemistry, Semmelweis University, Budapest, Hungary
| | - Peter Csermely
- Department of Medical Chemistry, Semmelweis University, Budapest, Hungary
| | - Daniel V Veres
- Department of Medical Chemistry, Semmelweis University, Budapest, Hungary.,Turbine Ltd., Budapest, Hungary
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36
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Wang Y, Yang Q, Chen X, Tang W, Zhou L, Chen Z, An Y, Zhang Z, Tang X, Zhao X. Phenotypic characterization of patients with activated PI3Kδ syndrome 1 presenting with features of systemic lupus erythematosus. Genes Dis 2020; 8:907-917. [PMID: 34522717 PMCID: PMC8427252 DOI: 10.1016/j.gendis.2020.04.012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Accepted: 04/22/2020] [Indexed: 10/26/2022] Open
Abstract
Activated phosphoinositide 3-kinase δ syndrome 1 (APDS1) is a primary immunodeficiency disease caused by gain-of-function mutations in PIK3CD. Clinical features of autoimmune disease have been reported in patients with APDS1. In this study, we reported three patients with APDS1 presenting with systemic lupus erythematosus (SLE) phenotype. The clinical manifestations included recurrent respiratory tract infection, lymphoproliferation, Coombs-positive hemolytic anemia, decreased complement fractions, positive antinuclear antibodies, renal complications related to SLE associated diseases, which met the clinical spectrum of APDS1 and the classification criteria of SLE. The immunological phenotype included an inversion in the CD4:CD8 ratio, an increase in both non-circulating Tfh CD4+ memory T and circulating Tfh populations, a low level of recent thymic emigrant T cells, overexpression of CD57 on T cells, and a decrease in B cells with fewer antibody class switch recombination. These phenotypes detected in patients with APDS1 presenting with SLE were resemble that in patients with APDS1 presenting without SLE. Meanwhile, we described the effect of glucocorticoids and rapamycin therapy on patients with APDS1. The phosphorylation of S6 at Ser235/236 was inhibited in patients with APDS1 who underwent glucocorticoids therapy, including two who presented with SLE phenotype. The phosphorylation of AKT at Ser473 and phosphorylation of S6 at Ser235/236 were inhibited in other patients with APDS1 who underwent rapamycin therapy. Here, we showed the coexistence of immunodeficiency and SLE phenotype in APDS1, and the inhibition of rapamycin in activated Akt-mTOR signaling pathway.
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Affiliation(s)
- Yanping Wang
- National Clinical Research Center for Child Health and Disorders (Chongqing), Children's Hospital ofChongqing Medical University, Chongqing, 400014, PR China.,China International Science and Technology Cooperation Base of Child Development and Critical Disorders, Children's Hospital of Chongqing Medical University, Chongqing, 400014, PR China.,Chongqing Key Laboratory of Child Infection and Immunity, Children's Hospital of Chongqing Medical University, Chongqing, 400014, PR China
| | - Qiuyun Yang
- National Clinical Research Center for Child Health and Disorders (Chongqing), Children's Hospital ofChongqing Medical University, Chongqing, 400014, PR China.,China International Science and Technology Cooperation Base of Child Development and Critical Disorders, Children's Hospital of Chongqing Medical University, Chongqing, 400014, PR China.,Chongqing Key Laboratory of Child Infection and Immunity, Children's Hospital of Chongqing Medical University, Chongqing, 400014, PR China
| | - Xuemei Chen
- National Clinical Research Center for Child Health and Disorders (Chongqing), Children's Hospital ofChongqing Medical University, Chongqing, 400014, PR China.,China International Science and Technology Cooperation Base of Child Development and Critical Disorders, Children's Hospital of Chongqing Medical University, Chongqing, 400014, PR China.,Chongqing Key Laboratory of Child Infection and Immunity, Children's Hospital of Chongqing Medical University, Chongqing, 400014, PR China
| | - Wenjing Tang
- Division of Rheumatology and Immunology, Children's Hospital of Chongqing Medical University, Chongqing, 400014, PR China
| | - Lina Zhou
- National Clinical Research Center for Child Health and Disorders (Chongqing), Children's Hospital ofChongqing Medical University, Chongqing, 400014, PR China.,China International Science and Technology Cooperation Base of Child Development and Critical Disorders, Children's Hospital of Chongqing Medical University, Chongqing, 400014, PR China.,Chongqing Key Laboratory of Child Infection and Immunity, Children's Hospital of Chongqing Medical University, Chongqing, 400014, PR China
| | - Zhi Chen
- National Clinical Research Center for Child Health and Disorders (Chongqing), Children's Hospital ofChongqing Medical University, Chongqing, 400014, PR China.,China International Science and Technology Cooperation Base of Child Development and Critical Disorders, Children's Hospital of Chongqing Medical University, Chongqing, 400014, PR China.,Chongqing Key Laboratory of Child Infection and Immunity, Children's Hospital of Chongqing Medical University, Chongqing, 400014, PR China
| | - Yunfei An
- Division of Rheumatology and Immunology, Children's Hospital of Chongqing Medical University, Chongqing, 400014, PR China
| | - Zhiyong Zhang
- Division of Rheumatology and Immunology, Children's Hospital of Chongqing Medical University, Chongqing, 400014, PR China
| | - Xuemei Tang
- Division of Rheumatology and Immunology, Children's Hospital of Chongqing Medical University, Chongqing, 400014, PR China
| | - Xiaodong Zhao
- National Clinical Research Center for Child Health and Disorders (Chongqing), Children's Hospital ofChongqing Medical University, Chongqing, 400014, PR China.,China International Science and Technology Cooperation Base of Child Development and Critical Disorders, Children's Hospital of Chongqing Medical University, Chongqing, 400014, PR China.,Chongqing Key Laboratory of Child Infection and Immunity, Children's Hospital of Chongqing Medical University, Chongqing, 400014, PR China.,Division of Rheumatology and Immunology, Children's Hospital of Chongqing Medical University, Chongqing, 400014, PR China
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37
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Carroll B. Spatial regulation of mTORC1 signalling: Beyond the Rag GTPases. Semin Cell Dev Biol 2020; 107:103-111. [PMID: 32122730 DOI: 10.1016/j.semcdb.2020.02.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 02/17/2020] [Accepted: 02/20/2020] [Indexed: 12/15/2022]
Abstract
The mechanistic (or mammalian) Target of Rapamycin Complex 1 (mTORC1) is a central regulator of cell growth and metabolism. By integrating mitogenic signals, mTORC1-dependent phosphorylation of substrates dictates the balance between anabolic, pro-growth and catabolic, recycling processes in the cell. The discovery that amino acids activate mTORC1 by promoting its translocation to the lysosome was a fundamental advance in the understanding of mTORC1 signalling. It has since become clear that the lysosome-cytoplasm shuttling of mTORC1 represents just one layer of spatial control of this signalling pathway. This review will focus on exploring the subcellular localisation of mTORC1 and its regulators to multiple sites within the cell. We will discuss how these spatially distinct regions such as endoplasmic reticulum, plasma membrane and the endosomal pathway co-operate to transduce nutrient availability to mTORC1, allowing for tight control of cell growth.
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Affiliation(s)
- Bernadette Carroll
- School of Biochemistry, Biomedical Sciences Building, University Walk, Bristol, BS8, United Kingdom.
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38
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Yumimoto K, Nakayama KI. Recent insight into the role of FBXW7 as a tumor suppressor. Semin Cancer Biol 2020; 67:1-15. [PMID: 32113998 DOI: 10.1016/j.semcancer.2020.02.017] [Citation(s) in RCA: 68] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Revised: 02/15/2020] [Accepted: 02/26/2020] [Indexed: 12/12/2022]
Abstract
FBXW7 (also known as Fbw7, Sel10, hCDC4, or hAgo) is a tumor suppressor and the most frequently mutated member of the F-box protein family in human cancers. FBXW7 functions as the substrate recognition component of an SCF-type E3 ubiquitin ligase. It specifically controls the proteasome-mediated degradation of many oncoproteins such as c-MYC, NOTCH, KLF5, cyclin E, c-JUN, and MCL1. In this review, we summarize the molecular and biological features of FBXW7 and its substrates as well as the impact of mutations of FBXW7 on cancer development. We also address the clinical potential of anticancer therapy targeting FBXW7.
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Affiliation(s)
- Kanae Yumimoto
- Department of Molecular and Cellular Biology, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, Fukuoka, 812-8582, Japan
| | - Keiichi I Nakayama
- Department of Molecular and Cellular Biology, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, Fukuoka, 812-8582, Japan.
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39
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Giguère V. DNA-PK, Nuclear mTOR, and the Androgen Pathway in Prostate Cancer. Trends Cancer 2020; 6:337-347. [PMID: 32209447 DOI: 10.1016/j.trecan.2020.01.015] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Revised: 01/21/2020] [Accepted: 01/23/2020] [Indexed: 02/07/2023]
Abstract
Androgen and its receptor (AR) are major drivers of prostate cancer (PCa), a leading cause of mortality in aging men. Thus, understanding the numerous mechanisms by which AR can promote the growth and proliferation of PCa cells and enable their escape from hormone-dependent therapies, eventually leading to metastasis and death of the patient, is essential to discover alternative therapeutic approaches. Recently, two structurally related members of the phosphatidylinositol 3-kinase-like protein kinase (PIKK) family, DNA-dependent protein kinase (DNA-PK) and mammalian target of rapamycin (mTOR), were shown to have a direct role in modulating AR activity on chromatin of PCa cells. In this review, the common features of DNA-PK and mTOR and the similarities in their noncanonical roles as transcription coregulators of the AR are highlighted. An outlook on how these findings could be translated into new approaches to manage and treat PCa is provided.
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Affiliation(s)
- Vincent Giguère
- Goodman Cancer Research Centre, McGill University, Montréal, QC, H3G 1Y6, Canada.
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40
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Non-canonical mTORC2 Signaling Regulates Brown Adipocyte Lipid Catabolism through SIRT6-FoxO1. Mol Cell 2020; 75:807-822.e8. [PMID: 31442424 DOI: 10.1016/j.molcel.2019.07.023] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Revised: 05/30/2019] [Accepted: 07/15/2019] [Indexed: 12/12/2022]
Abstract
mTORC2 controls glucose and lipid metabolism, but the mechanisms are unclear. Here, we show that conditionally deleting the essential mTORC2 subunit Rictor in murine brown adipocytes inhibits de novo lipid synthesis, promotes lipid catabolism and thermogenesis, and protects against diet-induced obesity and hepatic steatosis. AKT kinases are the canonical mTORC2 substrates; however, deleting Rictor in brown adipocytes appears to drive lipid catabolism by promoting FoxO1 deacetylation independently of AKT, and in a pathway distinct from its positive role in anabolic lipid synthesis. This facilitates FoxO1 nuclear retention, enhances lipid uptake and lipolysis, and potentiates UCP1 expression. We provide evidence that SIRT6 is the FoxO1 deacetylase suppressed by mTORC2 and show an endogenous interaction between SIRT6 and mTORC2 in both mouse and human cells. Our findings suggest a new paradigm of mTORC2 function filling an important gap in our understanding of this more mysterious mTOR complex.
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41
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Wang Y, Huang Y, Liu J, Zhang J, Xu M, You Z, Peng C, Gong Z, Liu W. Acetyltransferase GCN5 regulates autophagy and lysosome biogenesis by targeting TFEB. EMBO Rep 2020; 21:e48335. [PMID: 31750630 PMCID: PMC6945067 DOI: 10.15252/embr.201948335] [Citation(s) in RCA: 86] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2019] [Revised: 10/04/2019] [Accepted: 10/28/2019] [Indexed: 12/20/2022] Open
Abstract
Accumulating evidence highlights the role of histone acetyltransferase GCN5 in the regulation of cell metabolism in metazoans. Here, we report that GCN5 is a negative regulator of autophagy, a lysosome-dependent catabolic mechanism. In animal cells and Drosophila, GCN5 inhibits the biogenesis of autophagosomes and lysosomes by targeting TFEB, the master transcription factor for autophagy- and lysosome-related gene expression. We show that GCN5 is a specific TFEB acetyltransferase, and acetylation by GCN5 results in the decrease in TFEB transcriptional activity. Induction of autophagy inactivates GCN5, accompanied by reduced TFEB acetylation and increased lysosome formation. We further demonstrate that acetylation at K274 and K279 disrupts the dimerization of TFEB and the binding of TFEB to its target gene promoters. In a Tau-based neurodegenerative Drosophila model, deletion of dGcn5 improves the clearance of Tau protein aggregates and ameliorates the neurodegenerative phenotypes. Together, our results reveal GCN5 as a novel conserved TFEB regulator, and the regulatory mechanisms may be involved in autophagy- and lysosome-related physiological and pathological processes.
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Affiliation(s)
- Yusha Wang
- Department of Biochemistry and Department of Cardiology of the Second Affiliated HospitalZhejiang University School of MedicineHangzhouChina
| | - Yewei Huang
- Department of Biochemistry and Department of Cardiology of the Second Affiliated HospitalZhejiang University School of MedicineHangzhouChina
| | - Jiaqi Liu
- Department of Biochemistry and Department of Cardiology of the Second Affiliated HospitalZhejiang University School of MedicineHangzhouChina
| | - Jinna Zhang
- Department of Biochemistry and Department of Cardiology of the Second Affiliated HospitalZhejiang University School of MedicineHangzhouChina
| | - Mingming Xu
- Department of Biochemistry and Department of Cardiology of the Second Affiliated HospitalZhejiang University School of MedicineHangzhouChina
| | - Zhiyuan You
- Department of Biochemistry and Department of Cardiology of the Second Affiliated HospitalZhejiang University School of MedicineHangzhouChina
| | - Chao Peng
- National Center for Protein Science ShanghaiInstitute of Biochemistry and Cell BiologyShanghai Institutes of Biological SciencesChinese Academy of SciencesShanghaiChina
| | - Zhefeng Gong
- Department of NeurobiologyKey Laboratory of Medical Neurobiology of the Ministry of Health of ChinaZhejiang University School of MedicineHangzhouChina
| | - Wei Liu
- Department of Biochemistry and Department of Cardiology of the Second Affiliated HospitalZhejiang University School of MedicineHangzhouChina
- Collaborative Innovation Center for Diagnosis and Treatment of Infectious DiseaseFirst Affiliated HospitalZhejiang University School of MedicineHangzhouChina
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42
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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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43
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Ruicci KM, Plantinga P, Pinto N, Khan MI, Stecho W, Dhaliwal SS, Yoo J, Fung K, MacNeil D, Mymryk JS, Barrett JW, Howlett CJ, Nichols AC. Disruption of the RICTOR/mTORC2 complex enhances the response of head and neck squamous cell carcinoma cells to PI3K inhibition. Mol Oncol 2019; 13:2160-2177. [PMID: 31393061 PMCID: PMC6763779 DOI: 10.1002/1878-0261.12558] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2018] [Revised: 07/28/2019] [Accepted: 08/07/2019] [Indexed: 12/19/2022] Open
Abstract
Phosphoinositide 3-kinase (PI3K) is aberrantly activated in head and neck squamous cell carcinomas (HNSCC) and plays a pivotal role in tumorigenesis by driving Akt signaling, leading to cell survival and proliferation. Phosphorylation of Akt Thr308 by PI3K-PDK1 and Akt Ser473 by mammalian target of rapamycin complex 2 (mTORC2) activates Akt. Targeted inhibition of PI3K is a major area of preclinical and clinical investigation as it reduces Akt Thr308 phosphorylation, suppressing downstream mTORC1 activity. However, inhibition of mTORC1 releases feedback inhibition of mTORC2, resulting in a resurgence of Akt activation mediated by mTORC2. While the role of PI3K-activated Akt signaling is well established in HNSCC, the significance of mTORC2-driven Akt signaling has not been thoroughly examined. Here we explore the expression and function of mTORC2 and its obligate subunit RICTOR in HNSCC primary tumors and cell lines. We find RICTOR to be overexpressed in a subset of HNSCC tumors, including those with PIK3CA or EGFR gene amplifications. Whereas overexpression of RICTOR reduced susceptibility of HNSCC tumor cells to PI3K inhibition, genetic ablation of RICTOR using CRISPR/Cas9 sensitized cells to PI3K inhibition, as well as to EGFR inhibition and cisplatin treatment. Further, mTORC2 disruption led to reduced viability and colony forming abilities of HNSCC cells relative to their parental lines and induced loss of both activating Akt phosphorylation modifications (Thr308 and Ser473). Taken together, our findings establish RICTOR/mTORC2 as a critical oncogenic complex in HNSCC and rationalize the development of an mTORC2-specific inhibitor for use in HNSCC, either combined with agents already under investigation, or as an independent therapy.
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Affiliation(s)
- Kara M. Ruicci
- Department of Otolaryngology – Head and Neck Surgery, Schulich School of Medicine & DentistryWestern UniversityLondonCanada
- Department of Pathology & Laboratory Medicine, Schulich School of Medicine & DentistryWestern UniversityLondonCanada
| | - Paul Plantinga
- Department of Pathology & Laboratory Medicine, Schulich School of Medicine & DentistryWestern UniversityLondonCanada
| | - Nicole Pinto
- Department of Otolaryngology – Head and Neck Surgery, Schulich School of Medicine & DentistryWestern UniversityLondonCanada
| | - Mohammed I. Khan
- Department of Otolaryngology – Head and Neck Surgery, Schulich School of Medicine & DentistryWestern UniversityLondonCanada
| | - William Stecho
- Department of Pathology & Laboratory Medicine, Schulich School of Medicine & DentistryWestern UniversityLondonCanada
| | - Sandeep S. Dhaliwal
- Department of Otolaryngology – Head and Neck Surgery, Schulich School of Medicine & DentistryWestern UniversityLondonCanada
- Department of Oncology, Schulich School of Medicine & DentistryWestern UniversityLondonCanada
| | - John Yoo
- Department of Otolaryngology – Head and Neck Surgery, Schulich School of Medicine & DentistryWestern UniversityLondonCanada
- Department of Oncology, Schulich School of Medicine & DentistryWestern UniversityLondonCanada
| | - Kevin Fung
- Department of Otolaryngology – Head and Neck Surgery, Schulich School of Medicine & DentistryWestern UniversityLondonCanada
- Department of Oncology, Schulich School of Medicine & DentistryWestern UniversityLondonCanada
| | - Danielle MacNeil
- Department of Otolaryngology – Head and Neck Surgery, Schulich School of Medicine & DentistryWestern UniversityLondonCanada
- Department of Oncology, Schulich School of Medicine & DentistryWestern UniversityLondonCanada
| | - Joe S. Mymryk
- Department of Otolaryngology – Head and Neck Surgery, Schulich School of Medicine & DentistryWestern UniversityLondonCanada
- Department of Oncology, Schulich School of Medicine & DentistryWestern UniversityLondonCanada
- Department of Microbiology and Immunology, Schulich School of Medicine & DentistryWestern UniversityLondonCanada
| | - John W. Barrett
- Department of Otolaryngology – Head and Neck Surgery, Schulich School of Medicine & DentistryWestern UniversityLondonCanada
| | - Christopher J. Howlett
- Department of Pathology & Laboratory Medicine, Schulich School of Medicine & DentistryWestern UniversityLondonCanada
| | - Anthony C. Nichols
- Department of Otolaryngology – Head and Neck Surgery, Schulich School of Medicine & DentistryWestern UniversityLondonCanada
- Department of Pathology & Laboratory Medicine, Schulich School of Medicine & DentistryWestern UniversityLondonCanada
- Department of Oncology, Schulich School of Medicine & DentistryWestern UniversityLondonCanada
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Demas DM, Demo S, Fallah Y, Clarke R, Nephew KP, Althouse S, Sandusky G, He W, Shajahan-Haq AN. Glutamine Metabolism Drives Growth in Advanced Hormone Receptor Positive Breast Cancer. Front Oncol 2019; 9:686. [PMID: 31428575 PMCID: PMC6688514 DOI: 10.3389/fonc.2019.00686] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 07/12/2019] [Indexed: 01/08/2023] Open
Abstract
Dependence on the glutamine pathway is increased in advanced breast cancer cell models and tumors regardless of hormone receptor status or function. While 70% of breast cancers are estrogen receptor positive (ER+) and depend on estrogen signaling for growth, advanced ER+ breast cancers grow independent of estrogen. Cellular changes in amino acids such as glutamine are sensed by the mammalian target of rapamycin (mTOR) complex, mTORC1, which is often deregulated in ER+ advanced breast cancer. Inhibitor of mTOR, such as everolimus, has shown modest clinical activity in ER+ breast cancers when given with an antiestrogen. Here we show that breast cancer cell models that are estrogen independent and antiestrogen resistant are more dependent on glutamine for growth compared with their sensitive parental cell lines. Co-treatment of CB-839, an inhibitor of GLS, an enzyme that converts glutamine to glutamate, and everolimus interrupts the growth of these endocrine resistant xenografts. Using human tumor microarrays, we show that GLS is significantly higher in human breast cancer tumors with increased tumor grade, stage, ER-negative and progesterone receptor (PR) negative status. Moreover, GLS levels were significantly higher in breast tumors from African-American women compared with Caucasian women regardless of ER or PR status. Among patients treated with endocrine therapy, high GLS expression was associated with decreased disease free survival (DFS) from a multivariable model with GLS expression treated as dichotomous. Collectively, these findings suggest a complex biology for glutamine metabolism in driving breast cancer growth. Moreover, targeting GLS and mTOR in advanced breast cancer may be a novel therapeutic approach in advanced ER+ breast cancer.
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Affiliation(s)
- Diane M Demas
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC, United States
| | - Susan Demo
- Calithera Biosciences, South San Francisco, CA, United States
| | - Yassi Fallah
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC, United States
| | - Robert Clarke
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC, United States
| | - Kenneth P Nephew
- Cell, Molecular and Cancer Biology, Medical Sciences, Indiana University School of Medicine, Bloomington, IN, United States
| | - Sandra Althouse
- Department of Biostatistics, Indiana University School of Medicine, Indianapolis, IN, United States
| | - George Sandusky
- Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, IN, United States
| | - Wei He
- Program in Genetics, Bioinformatics, and Computational Biology, VT BIOTRANS, Virginia Tech, Blacksburg, VA, United States
| | - Ayesha N Shajahan-Haq
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC, United States
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45
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Yang JY, Madrakhimov SB, Ahn DH, Chang HS, Jung SJ, Nah SK, Park HY, Park TK. mTORC1 and mTORC2 are differentially engaged in the development of laser-induced CNV. Cell Commun Signal 2019; 17:64. [PMID: 31200728 PMCID: PMC6570852 DOI: 10.1186/s12964-019-0380-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Accepted: 06/04/2019] [Indexed: 12/16/2022] Open
Abstract
Background The mechanistic target of rapamycin (mTOR) pathway is a potential target to inhibit pathologic processes in choroidal neovascularization. However, the exact role of mTOR signaling in the development of CNV remains obscure. In this study, we assessed the role of mTORC1 and mTORC2 as well as the effect of rapamycin (sirolimus) on choroidal neovascularization (CNV) in a laser-induced mouse model. Methods In experiment A, we observed the natural course of CNV development and the dynamics of mTOR-related proteins during the 12 days after the laser injury. The expression of mTOR-related proteins was evaluated using Western blot (WB). Cryosections of CNV-induced mice were immunostained for the visualization of the vascular and extravascular components of the CNV. Experiment B was performed to confirm the critical period of mTOR signaling in the development of laser-induced CNV, we administered rapamycin before and/or during the active period of mTOR complexes. WB and immunofluorescence staining was performed to evaluate the mode of action and the effect of mTOR inhibition on CNV development. Results In experiment A, we detected high levels of p-mTOR S2448 and p-mTOR S2481 from the 5th to 12th day of laser injury. Immunofluorescence imaging of cryosections of mice sacrificed on day 7 revealed greater co-immunoreactivity of p-mTOR S2448 positive cells with CD11b and F4/80, while p-mTOR S2481 positive cells showed colocalization with CD31, α-SMA, and cytokeratin. In experiment B, rapamycin injection during the active period of mTOR signaling demonstrated near-complete inhibition of CNV lesion as well as significant induction of autophagy. Conclusion Our study suggests the mTOR as a critical player during CNV development in laser-induced mouse model through differentially acting with the mTORC1 and mTORC2. mTORC1 activity was high predominantly in inflammatory cells in CNV lesion, while mTORC2 activity was higher in vascular components and the RPE. Electronic supplementary material The online version of this article (10.1186/s12964-019-0380-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Jin Young Yang
- Department of Interdisciplinary Program in Biomedical Science, Soonchunhyang Graduate School, Bucheon Hospital, Bucheon, South Korea.,Laboratory for Translational Research on Retinal and Macular Degeneration, Soonchunhyang University Hospital Bucheon, Bucheon, South Korea
| | - Sanjar Batirovich Madrakhimov
- Department of Interdisciplinary Program in Biomedical Science, Soonchunhyang Graduate School, Bucheon Hospital, Bucheon, South Korea.,Laboratory for Translational Research on Retinal and Macular Degeneration, Soonchunhyang University Hospital Bucheon, Bucheon, South Korea
| | - Dong Hyuck Ahn
- Laboratory for Translational Research on Retinal and Macular Degeneration, Soonchunhyang University Hospital Bucheon, Bucheon, South Korea
| | - Hun Soo Chang
- Department of Medical Bioscience, Graduated School, Soonchunhyang University, Bucheon, South Korea
| | - Sang Joon Jung
- Department of Ophthalmology, College of Medicine, Soonchunhyang University, Cheonan, Choongchungnam-do, South Korea
| | - Seung Kwan Nah
- Department of Ophthalmology, College of Medicine, Soonchunhyang University, Cheonan, Choongchungnam-do, South Korea
| | - Ha Yan Park
- Laboratory for Translational Research on Retinal and Macular Degeneration, Soonchunhyang University Hospital Bucheon, Bucheon, South Korea
| | - Tae Kwann Park
- Department of Interdisciplinary Program in Biomedical Science, Soonchunhyang Graduate School, Bucheon Hospital, Bucheon, South Korea. .,Laboratory for Translational Research on Retinal and Macular Degeneration, Soonchunhyang University Hospital Bucheon, Bucheon, South Korea. .,Department of Ophthalmology, Soonchunhyang University Hospital Bucheon, #170, Jomaru-ro, Wonmi-gu, Bucheon, 14584, South Korea. .,Department of Ophthalmology, College of Medicine, Soonchunhyang University, Cheonan, Choongchungnam-do, South Korea. .,Department of Ophthalmology, College of Medicine, Soonchunhyang University, Bucheon Hospital, Bucheon, South Korea.
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46
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Sural-Fehr T, Singh H, Cantuti-Catelvetri L, Zhu H, Marshall MS, Rebiai R, Jastrzebski MJ, Givogri MI, Rasenick MM, Bongarzone ER. Inhibition of the IGF-1-PI3K-Akt-mTORC2 pathway in lipid rafts increases neuronal vulnerability in a genetic lysosomal glycosphingolipidosis. Dis Model Mech 2019; 12:dmm036590. [PMID: 31036560 PMCID: PMC6550048 DOI: 10.1242/dmm.036590] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Accepted: 04/11/2019] [Indexed: 12/25/2022] Open
Abstract
Glycosphingolipid (GSL) accumulation is implicated in the neuropathology of several lysosomal conditions, such as Krabbe disease, and may also contribute to neuronal and glial dysfunction in adult-onset conditions such as Parkinson's disease, Alzheimer's disease and multiple sclerosis. GSLs accumulate in cellular membranes and disrupt their structure; however, how membrane disruption leads to cellular dysfunction remains unknown. Using authentic cellular and animal models for Krabbe disease, we provide a mechanism explaining the inactivation of lipid raft (LR)-associated IGF-1-PI3K-Akt-mTORC2, a pathway of crucial importance for neuronal function and survival. We show that psychosine, the GSL that accumulates in Krabbe disease, leads to a dose-dependent LR-mediated inhibition of this pathway by uncoupling IGF-1 receptor phosphorylation from downstream Akt activation. This occurs by interfering with the recruitment of PI3K and mTORC2 to LRs. Akt inhibition can be reversed by sustained IGF-1 stimulation, but only during a time window before psychosine accumulation reaches a threshold level. Our study shows a previously unknown connection between LR-dependent regulation of mTORC2 activity at the cell surface and a genetic neurodegenerative disease. Our results show that LR disruption by psychosine desensitizes cells to extracellular growth factors by inhibiting signal transmission from the plasma membrane to intracellular compartments. This mechanism serves also as a mechanistic model to understand how alterations of the membrane architecture by the progressive accumulation of lipids undermines cell function, with potential implications in other genetic sphingolipidoses and adult neurodegenerative conditions. This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Tuba Sural-Fehr
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, IL 60612, USA
| | - Harinder Singh
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, IL 60612, USA
| | | | - Hongling Zhu
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, IL 60612, USA
| | - Michael S Marshall
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, IL 60612, USA
| | - Rima Rebiai
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, IL 60612, USA
| | - Martin J Jastrzebski
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, IL 60612, USA
| | - Maria I Givogri
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, IL 60612, USA
| | - Mark M Rasenick
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, IL 60612, USA
| | - Ernesto R Bongarzone
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, IL 60612, USA
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47
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Lamm N, Rogers S, Cesare AJ. The mTOR pathway: Implications for DNA replication. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2019; 147:17-25. [PMID: 30991055 DOI: 10.1016/j.pbiomolbio.2019.04.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Revised: 04/01/2019] [Accepted: 04/09/2019] [Indexed: 12/22/2022]
Abstract
DNA replication plays a central role in genome health. Deleterious alteration of replication dynamics, or "replication stress", is a key driver of genome instability and oncogenesis. The replication stress response is regulated by the ATR kinase, which functions to mitigate replication abnormalities through coordinated efforts that arrest the cell cycle and repair damaged replication forks. mTOR kinase regulates signaling networks that control cell growth and metabolism in response to environmental cues and cell stress. In this review, we discuss interconnectivity between the ATR and mTOR pathways, and provide putative mechanisms for mTOR engagement in DNA replication and the replication stress response. Finally, we describe how connectivity between mTOR and replication stress may be exploited for cancer therapy.
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Affiliation(s)
- Noa Lamm
- Genome Integrity Unit, Children's Medical Research Institute, University of Sydney, Westmead, New South Wales, 2145, Australia
| | - Samuel Rogers
- Genome Integrity Unit, Children's Medical Research Institute, University of Sydney, Westmead, New South Wales, 2145, Australia
| | - Anthony J Cesare
- Genome Integrity Unit, Children's Medical Research Institute, University of Sydney, Westmead, New South Wales, 2145, Australia.
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48
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Jhanwar-Uniyal M, Wainwright JV, Mohan AL, Tobias ME, Murali R, Gandhi CD, Schmidt MH. Diverse signaling mechanisms of mTOR complexes: mTORC1 and mTORC2 in forming a formidable relationship. Adv Biol Regul 2019; 72:51-62. [PMID: 31010692 DOI: 10.1016/j.jbior.2019.03.003] [Citation(s) in RCA: 169] [Impact Index Per Article: 33.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 03/25/2019] [Accepted: 03/25/2019] [Indexed: 02/07/2023]
Abstract
Activation of Mechanistic target of rapamycin (mTOR) signaling plays a crucial role in tumorigenesis of numerous malignancies including glioblastoma (GB). The Canonical PI3K/Akt/mTOR signaling cascade is commonly upregulated due to loss of the tumor suppressorm PTEN, a phosphatase that acts antagonistically to the kinase (PI3K) in conversion of PIP2 to PIP3. mTOR forms two multiprotein complexes, mTORC1 and mTORC2 which are composed of discrete protein binding partners to regulate cell growth, motility, and metabolism. These complexes are sensitive to distinct stimuli, as mTORC1 is sensitive to nutrients while mTORC2 is regulated via PI3K and growth factor signaling. The main function of mTORC1 is to regulate protein synthesis and cell growth through downstream molecules: 4E-BP1 (also called EIF4E-BP1) and S6K. On the other hand, mTORC2 is responsive to growth factor signaling by phosphorylating the C-terminal hydrophobic motif of some AGC kinases like Akt and SGK and it also plays a crucial role in maintenance of normal and cancer cells through its association with ribosomes, and is involved in cellular metabolic regulation. mTORC1 and mTORC2 regulate each other, as shown by the fact that Akt regulates PRAS40 phosphorylation, which disinhibits mTORC1 activity, while S6K regulates Sin1 to modulate mTORC2 activity. Allosteric inhibitors of mTOR, rapamycin and rapalogs, remained ineffective in clinical trials of Glioblastoma (GB) patients, in part due to their incomplete inhibition of mTORC1 as well as unexpected activation of mTOR via the loss of negative feedback loops. In recent years, novel ATP binding inhibitors of mTORC1 and mTORC2 suppress mTORC1 activity completely by total dephosphorylation of its downstream substrate pS6KSer235/236, while effectively suppressing mTORC2 activity, as demonstrated by complete dephosphorylation of pAKTSer473. Furthermore by these novel combined mTORC1/mTORC2 inhibitors reduced the proliferation and self-renewal of GB cancer stem cells. However, a search of more effective way to target mTOR has generated a third generation inhibitor of mTOR, "Rapalink", that bivalently combines rapamycin with an ATP-binding inhibitor, which effectively abolishes the mTORC1 activity. All in all, the effectiveness of inhibitors of mTOR complexes can be judged by their ability to suppress both mTORC1/mTORC2 and their ability to impede both cell proliferation and migration along with aberrant metabolic pathways.
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Affiliation(s)
- Meena Jhanwar-Uniyal
- Department of Neurosurgery, Westchester Medical Center / New York Medical College, Valhalla, NY, 10595, USA.
| | - John V Wainwright
- Department of Neurosurgery, Westchester Medical Center / New York Medical College, Valhalla, NY, 10595, USA
| | - Avinash L Mohan
- Department of Neurosurgery, Westchester Medical Center / New York Medical College, Valhalla, NY, 10595, USA
| | - Michael E Tobias
- Department of Neurosurgery, Westchester Medical Center / New York Medical College, Valhalla, NY, 10595, USA
| | - Raj Murali
- Department of Neurosurgery, Westchester Medical Center / New York Medical College, Valhalla, NY, 10595, USA
| | - Chirag D Gandhi
- Department of Neurosurgery, Westchester Medical Center / New York Medical College, Valhalla, NY, 10595, USA
| | - Meic H Schmidt
- Department of Neurosurgery, Westchester Medical Center / New York Medical College, Valhalla, NY, 10595, USA
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Gleason CE, Oses-Prieto JA, Li KH, Saha B, Situ G, Burlingame AL, Pearce D. Phosphorylation at distinct subcellular locations underlies specificity in mTORC2-mediated activation of SGK1 and Akt. J Cell Sci 2019; 132:jcs.224931. [PMID: 30837283 DOI: 10.1242/jcs.224931] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Accepted: 02/21/2019] [Indexed: 02/04/2023] Open
Abstract
mTORC2 lies at the intersection of signaling pathways that control metabolism and ion transport through phosphorylation of the AGC-family kinases, the Akt and SGK1 proteins. How mTORC2 targets these functionally distinct downstream effectors in a context-specific manner is not known. Here, we show that the salt- and blood pressure-regulatory hormone, angiotensin II (AngII) stimulates selective mTORC2-dependent phosphorylation of SGK1 (S422) but not Akt (S473 and equivalent sites). Conventional PKC (cPKC), a critical mediator of the angiotensin type I receptor (AT1R, also known as AGTR1) signaling, regulates the subcellular localization of SIN1 (also known as MAPKAP1) and SGK1. Inhibition of cPKC catalytic activity disturbs SIN1 and SGK1 subcellular localization, re-localizing them from the nucleus and a perinuclear compartment to the plasma membrane in advance of hormonal stimulation. Surprisingly, pre-targeting of SIN1 and SGK1 to the plasma membrane prevents SGK1 S422 but not Akt S473 phosphorylation. Additionally, we identify three sites on SIN1 (S128, S315 and S356) that are phosphorylated in response to cPKC activation. Collectively, these data demonstrate that SGK1 activation occurs at a distinct subcellular compartment from that of Akt and suggests a mechanism for the selective activation of these functionally distinct mTORC2 targets through subcellular partitioning of mTORC2 activity.
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Affiliation(s)
- Catherine E Gleason
- Department of Medicine, Division of Nephrology, UCSF, San Francisco, CA 94143, USA
| | - Juan A Oses-Prieto
- Departments of Chemistry and Pharmaceutical Chemistry, UCSF, San Francisco, CA 94143, USA
| | - Kathy H Li
- Departments of Chemistry and Pharmaceutical Chemistry, UCSF, San Francisco, CA 94143, USA
| | - Bidisha Saha
- Department of Medicine, Division of Nephrology, UCSF, San Francisco, CA 94143, USA
| | - Gavin Situ
- Department of Medicine, Division of Nephrology, UCSF, San Francisco, CA 94143, USA
| | - Alma L Burlingame
- Departments of Chemistry and Pharmaceutical Chemistry, UCSF, San Francisco, CA 94143, USA
| | - David Pearce
- Department of Medicine, Division of Nephrology, UCSF, San Francisco, CA 94143, USA
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50
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The DNase Activity of Kaposi's Sarcoma-Associated Herpesvirus SOX Protein Serves an Important Role in Viral Genome Processing during Lytic Replication. J Virol 2019; 93:JVI.01983-18. [PMID: 30728255 DOI: 10.1128/jvi.01983-18] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Accepted: 01/28/2019] [Indexed: 01/18/2023] Open
Abstract
The Kaposi's sarcoma-associated herpesvirus (KSHV) alkaline exonuclease SOX, encoded by open reading frame 37 (ORF37), is a bifunctional early-lytic-phase protein that possesses alkaline 5'-to-3' DNase activity and promotes host shutoff at the mRNA level during productive lytic infection. While the SOX protein is well characterized for drastically impairing cellular gene expression, little is known about the impact of its DNase activity on the KSHV genome and life cycle and the biology of KSHV infections. Here, we introduced a previously described DNase-inactivating Glu129His (Q129H) mutation into the ORF37 gene of the viral genome to generate ORF37-Q129H recombinant virus (the Q129H mutant) and investigated the effects of loss or inactivation of DNase activity on viral genome replication, cleavage, and packaging. For the first time, we provide experimental evidence that the DNase activity of the SOX protein does not affect viral latent/lytic DNA synthesis but is required for cleavage and processing of the KSHV genome during lytic replication. Interestingly, the Q129H mutation severely impaired intranuclear processing of progeny virions compared to the wild-type ORF37, as assessed by pulsed-field and Gardella gel electrophoresis, electron microscopy, and single-molecule analysis of replicating DNA (SMARD) assays. Complementation with ORF37-wt (wild type) or BGLF5 (the KSHV protein homolog in Epstein-Barr virus) in 293L/Q129H cells restored the viral genome encapsidation defects. Together, these results indicated that ORF37's proposed DNase activity is essential for viral genome processing and encapsidation and, hence, can be targeted for designing antiviral agents to block KSHV virion production.IMPORTANCE Kaposi's sarcoma (KS)-associated herpesvirus is the causative agent of multiple malignancies, predominantly in immunocompromised individuals, including HIV/AIDS patients. Reduced incidence of KS in HIV/AIDS patients receiving antiherpetic drugs to block lytic replication confirms the role of lytic DNA replication and gene products in KSHV-mediated tumorigenesis. Herpesvirus lytic replication results in the production of complex concatemeric DNA, which is cleaved into unit length viral DNA for packaging into the infectious virions. The conserved herpesviral alkaline exonucleases play an important role in viral genome cleavage and packaging. Here, by using the previously described Q129H mutant virus that selectively lacks DNase activity but retains host shutoff activity, we provide experimental evidence confirming that the DNase function of the KSHV SOX protein is essential for viral genome processing and packaging and capsid maturation into the cytoplasm during lytic replication in infected cells. This led to the identification of ORF37's DNase activity as a potential target for antiviral therapeutics.
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