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Cormerais Y, Massard PA, Vucetic M, Giuliano S, Tambutté E, Durivault J, Vial V, Endou H, Wempe MF, Parks SK, Pouyssegur J. The glutamine transporter ASCT2 (SLC1A5) promotes tumor growth independently of the amino acid transporter LAT1 (SLC7A5). J Biol Chem 2018; 293:2877-2887. [PMID: 29326164 PMCID: PMC5827425 DOI: 10.1074/jbc.ra117.001342] [Citation(s) in RCA: 116] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2017] [Revised: 12/27/2017] [Indexed: 12/12/2022] Open
Abstract
The transporters for glutamine and essential amino acids, ASCT2 (solute carrier family 1 member 5, SLC1A5) and LAT1 (solute carrier family 7 member 5, SLC7A5), respectively, are overexpressed in aggressive cancers and have been identified as cancer-promoting targets. Moreover, previous work has suggested that glutamine influx via ASCT2 triggers essential amino acids entry via the LAT1 exchanger, thus activating mechanistic target of rapamycin complex 1 (mTORC1) and stimulating growth. Here, to further investigate whether these two transporters are functionally coupled, we compared the respective knockout (KO) of either LAT1 or ASCT2 in colon (LS174T) and lung (A549) adenocarcinoma cell lines. Although ASCT2KO significantly reduced glutamine import (>60% reduction), no impact on leucine uptake was observed in both cell lines. Although an in vitro growth-reduction phenotype was observed in A549-ASCT2KO cells only, we found that genetic disruption of ASCT2 strongly decreased tumor growth in both cell lines. However, in sharp contrast to LAT1KO cells, ASCT2KO cells displayed no amino acid (AA) stress response (GCN2/EIF2a/ATF4) or altered mTORC1 activity (S6K1/S6). We therefore conclude that ASCT2KO reduces tumor growth by limiting AA import, but that this effect is independent of LAT1 activity. These data were further supported by in vitro cell proliferation experiments performed in the absence of glutamine. Together these results confirm and extend ASCT2's pro-tumoral role and indicate that the proposed functional coupling model of ASCT2 and LAT1 is not universal across different cancer types.
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Affiliation(s)
- Yann Cormerais
- Medical Biology Department, Centre Scientifique de Monaco (CSM), MC 98000 Monaco
| | - Pierre André Massard
- Medical Biology Department, Centre Scientifique de Monaco (CSM), MC 98000 Monaco
| | - Milica Vucetic
- Medical Biology Department, Centre Scientifique de Monaco (CSM), MC 98000 Monaco
| | - Sandy Giuliano
- Medical Biology Department, Centre Scientifique de Monaco (CSM), MC 98000 Monaco
| | - Eric Tambutté
- Medical Biology Department, Centre Scientifique de Monaco (CSM), MC 98000 Monaco
| | - Jerome Durivault
- Medical Biology Department, Centre Scientifique de Monaco (CSM), MC 98000 Monaco
| | - Valérie Vial
- Medical Biology Department, Centre Scientifique de Monaco (CSM), MC 98000 Monaco
| | | | - Michael F Wempe
- School of Pharmacy, Anschutz Medical Campus, University of Colorado Denver, Aurora, Colorado 80045
| | - Scott K Parks
- Medical Biology Department, Centre Scientifique de Monaco (CSM), MC 98000 Monaco.
| | - Jacques Pouyssegur
- Medical Biology Department, Centre Scientifique de Monaco (CSM), MC 98000 Monaco; Institute for Research on Cancer and Aging (IRCAN), CNRS, INSERM, Centre A. Lacassagne, University of Nice Sophia Antipolis, 06088 Nice, France.
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152
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He XD, Gong W, Zhang JN, Nie J, Yao CF, Guo FS, Lin Y, Wu XH, Li F, Li J, Sun WC, Wang ED, An YP, Tang HR, Yan GQ, Yang PY, Wei Y, Mao YZ, Lin PC, Zhao JY, Xu Y, Xu W, Zhao SM. Sensing and Transmitting Intracellular Amino Acid Signals through Reversible Lysine Aminoacylations. Cell Metab 2018; 27:151-166.e6. [PMID: 29198988 DOI: 10.1016/j.cmet.2017.10.015] [Citation(s) in RCA: 90] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Revised: 08/17/2017] [Accepted: 10/26/2017] [Indexed: 02/05/2023]
Abstract
Amino acids are known regulators of cellular signaling and physiology, but how they are sensed intracellularly is not fully understood. Herein, we report that each aminoacyl-tRNA synthetase (ARS) senses its cognate amino acid sufficiency through catalyzing the formation of lysine aminoacylation (K-AA) on its specific substrate proteins. At physiologic levels, amino acids promote ARSs bound to their substrates and form K-AAs on the ɛ-amine of lysines in their substrates by producing reactive aminoacyl adenylates. The K-AA marks can be removed by deacetylases, such as SIRT1 and SIRT3, employing the same mechanism as that involved in deacetylation. These dynamically regulated K-AAs transduce signals of their respective amino acids. Reversible leucylation on ras-related GTP-binding protein A/B regulates activity of the mammalian target of rapamycin complex 1. Glutaminylation on apoptosis signal-regulating kinase 1 suppresses apoptosis. We discovered non-canonical functions of ARSs and revealed systematic and functional amino acid sensing and signal transduction networks.
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Affiliation(s)
- Xia-Di He
- Obstetrics and Gynecology Hospital of Fudan University, State Key Lab of Genetic Engineering, School of Life Sciences and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, PRC; Key Laboratory of Reproduction Regulation of NPFPC (SIPPR,IRD) and Collaborative Innovation Center for Genetics and Development, Fudan University, Shanghai 200032, PRC; State Key Laboratory of Biotherapy/ Collaborative Innovation Center for Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, PRC
| | - Wei Gong
- Obstetrics and Gynecology Hospital of Fudan University, State Key Lab of Genetic Engineering, School of Life Sciences and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, PRC; Fudan University Shanghai Cancer Center, Fudan University, Shanghai 200032, PRC
| | - Jia-Nong Zhang
- Obstetrics and Gynecology Hospital of Fudan University, State Key Lab of Genetic Engineering, School of Life Sciences and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, PRC; Key Laboratory of Reproduction Regulation of NPFPC (SIPPR,IRD) and Collaborative Innovation Center for Genetics and Development, Fudan University, Shanghai 200032, PRC; State Key Laboratory of Biotherapy/ Collaborative Innovation Center for Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, PRC
| | - Ji Nie
- Obstetrics and Gynecology Hospital of Fudan University, State Key Lab of Genetic Engineering, School of Life Sciences and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, PRC; Key Laboratory of Reproduction Regulation of NPFPC (SIPPR,IRD) and Collaborative Innovation Center for Genetics and Development, Fudan University, Shanghai 200032, PRC; State Key Laboratory of Biotherapy/ Collaborative Innovation Center for Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, PRC
| | - Cui-Fang Yao
- Obstetrics and Gynecology Hospital of Fudan University, State Key Lab of Genetic Engineering, School of Life Sciences and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, PRC; Key Laboratory of Reproduction Regulation of NPFPC (SIPPR,IRD) and Collaborative Innovation Center for Genetics and Development, Fudan University, Shanghai 200032, PRC; State Key Laboratory of Biotherapy/ Collaborative Innovation Center for Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, PRC
| | - Fu-Shen Guo
- Obstetrics and Gynecology Hospital of Fudan University, State Key Lab of Genetic Engineering, School of Life Sciences and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, PRC; Key Laboratory of Reproduction Regulation of NPFPC (SIPPR,IRD) and Collaborative Innovation Center for Genetics and Development, Fudan University, Shanghai 200032, PRC
| | - Yan Lin
- Obstetrics and Gynecology Hospital of Fudan University, State Key Lab of Genetic Engineering, School of Life Sciences and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, PRC; Key Laboratory of Reproduction Regulation of NPFPC (SIPPR,IRD) and Collaborative Innovation Center for Genetics and Development, Fudan University, Shanghai 200032, PRC
| | - Xiao-Hui Wu
- Obstetrics and Gynecology Hospital of Fudan University, State Key Lab of Genetic Engineering, School of Life Sciences and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, PRC; Institute of Developmental Biology and Molecular Medicine, Fudan University, Shanghai 200032, PRC
| | - Feng Li
- Obstetrics and Gynecology Hospital of Fudan University, State Key Lab of Genetic Engineering, School of Life Sciences and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, PRC; Key Laboratory of Reproduction Regulation of NPFPC (SIPPR,IRD) and Collaborative Innovation Center for Genetics and Development, Fudan University, Shanghai 200032, PRC; State Key Laboratory of Biotherapy/ Collaborative Innovation Center for Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, PRC
| | - Jie Li
- Obstetrics and Gynecology Hospital of Fudan University, State Key Lab of Genetic Engineering, School of Life Sciences and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, PRC; Fudan University Shanghai Cancer Center, Fudan University, Shanghai 200032, PRC
| | - Wei-Cheng Sun
- Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, PRC
| | - En-Duo Wang
- Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, PRC
| | - Yan-Peng An
- Obstetrics and Gynecology Hospital of Fudan University, State Key Lab of Genetic Engineering, School of Life Sciences and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, PRC; Key Laboratory of Reproduction Regulation of NPFPC (SIPPR,IRD) and Collaborative Innovation Center for Genetics and Development, Fudan University, Shanghai 200032, PRC
| | - Hui-Ru Tang
- Obstetrics and Gynecology Hospital of Fudan University, State Key Lab of Genetic Engineering, School of Life Sciences and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, PRC; Key Laboratory of Reproduction Regulation of NPFPC (SIPPR,IRD) and Collaborative Innovation Center for Genetics and Development, Fudan University, Shanghai 200032, PRC
| | - Guo-Quan Yan
- Obstetrics and Gynecology Hospital of Fudan University, State Key Lab of Genetic Engineering, School of Life Sciences and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, PRC
| | - Peng-Yuan Yang
- Obstetrics and Gynecology Hospital of Fudan University, State Key Lab of Genetic Engineering, School of Life Sciences and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, PRC
| | - Yun Wei
- Obstetrics and Gynecology Hospital of Fudan University, State Key Lab of Genetic Engineering, School of Life Sciences and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, PRC; Key Laboratory of Reproduction Regulation of NPFPC (SIPPR,IRD) and Collaborative Innovation Center for Genetics and Development, Fudan University, Shanghai 200032, PRC
| | - Yun-Zi Mao
- Obstetrics and Gynecology Hospital of Fudan University, State Key Lab of Genetic Engineering, School of Life Sciences and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, PRC; Key Laboratory of Reproduction Regulation of NPFPC (SIPPR,IRD) and Collaborative Innovation Center for Genetics and Development, Fudan University, Shanghai 200032, PRC
| | - Peng-Cheng Lin
- Key Laboratory for Tibet Plateau Phytochemistry of Qinghai Province, College of Pharmacy, Qinghai University for Nationalities, Xining 810007, PRC
| | - Jian-Yuan Zhao
- Obstetrics and Gynecology Hospital of Fudan University, State Key Lab of Genetic Engineering, School of Life Sciences and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, PRC; State Key Laboratory of Biotherapy/ Collaborative Innovation Center for Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, PRC
| | - Yanhui Xu
- Obstetrics and Gynecology Hospital of Fudan University, State Key Lab of Genetic Engineering, School of Life Sciences and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, PRC; Fudan University Shanghai Cancer Center, Fudan University, Shanghai 200032, PRC; CAS Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai 200031, PRC.
| | - Wei Xu
- Obstetrics and Gynecology Hospital of Fudan University, State Key Lab of Genetic Engineering, School of Life Sciences and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, PRC; Key Laboratory of Reproduction Regulation of NPFPC (SIPPR,IRD) and Collaborative Innovation Center for Genetics and Development, Fudan University, Shanghai 200032, PRC.
| | - Shi-Min Zhao
- Obstetrics and Gynecology Hospital of Fudan University, State Key Lab of Genetic Engineering, School of Life Sciences and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032, PRC; Key Laboratory of Reproduction Regulation of NPFPC (SIPPR,IRD) and Collaborative Innovation Center for Genetics and Development, Fudan University, Shanghai 200032, PRC; State Key Laboratory of Biotherapy/ Collaborative Innovation Center for Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, PRC.
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153
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Jüppner J, Mubeen U, Leisse A, Caldana C, Wiszniewski A, Steinhauser D, Giavalisco P. The target of rapamycin kinase affects biomass accumulation and cell cycle progression by altering carbon/nitrogen balance in synchronized Chlamydomonas reinhardtii cells. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2018; 93:355-376. [PMID: 29172247 DOI: 10.1111/tpj.13787] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2017] [Revised: 10/31/2017] [Accepted: 11/15/2017] [Indexed: 05/19/2023]
Abstract
Several metabolic processes tightly regulate growth and biomass accumulation. A highly conserved protein complex containing the target of rapamycin (TOR) kinase is known to integrate intra- and extracellular stimuli controlling nutrient allocation and hence cellular growth. Although several functions of TOR have been described in various heterotrophic eukaryotes, our understanding lags far behind in photosynthetic organisms. In the present investigation, we used the model alga Chlamydomonas reinhardtii to conduct a time-resolved analysis of molecular and physiological features throughout the diurnal cycle after TOR inhibition. Detailed examination of the cell cycle phases revealed that growth is not only repressed by 50%, but also that significant, non-linear delays in the progression can be observed. By using metabolomics analysis, we elucidated that the growth repression was mainly driven by differential carbon partitioning between anabolic and catabolic processes. Accordingly, the time-resolved analysis illustrated that metabolic processes including amino acid-, starch- and triacylglycerol synthesis, as well RNA degradation, were redirected within minutes of TOR inhibition. Here especially the high accumulation of nitrogen-containing compounds indicated that an active TOR kinase controls the carbon to nitrogen balance of the cell, which is responsible for biomass accumulation, growth and cell cycle progression.
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Affiliation(s)
- Jessica Jüppner
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476, Potsdam-Golm, Germany
| | - Umarah Mubeen
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476, Potsdam-Golm, Germany
| | - Andrea Leisse
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476, Potsdam-Golm, Germany
| | - Camila Caldana
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476, Potsdam-Golm, Germany
- Brazilian Bioethanol Science and Technology Laboratory/CNPEM, Rua Giuseppe Máximo Scolfano 10000, 13083-970, Campinas, Brazil
| | - Andrew Wiszniewski
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476, Potsdam-Golm, Germany
| | - Dirk Steinhauser
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476, Potsdam-Golm, Germany
| | - Patrick Giavalisco
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476, Potsdam-Golm, Germany
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154
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Abstract
Lymphangioleiomyomatosis (LAM) is a rare, low-grade, metastasizing neoplasm that arises from an unknown source, spreads via the lymphatics, and targets the lungs. All pulmonary structures become infiltrated with benign-appearing spindle and epithelioid cells (LAM cells) that express smooth-muscle and melanocyte-lineage markers, harbor mTOR-activating mutations in tuberous sclerosis complex (TSC) genes, and recruit abundant stromal cells. Elaboration of lymphangiogenic growth factors and matrix remodeling enzymes by LAM cells enables their access to lymphatic channels and likely drives the cystic lung remodeling that often culminates in respiratory failure. Dysregulated cellular signaling results in a shift from oxidative phosphorylation to glycolysis as the preferred mode of energy generation, to allow for the accumulation of biomass required for cell growth and tolerance of nutrient-poor, anaerobic environments. Symptomatic LAM occurs almost exclusively in females after menarche, highlighting the central but as yet poorly understood role for sex-restricted anatomical structures and/or hormones in disease pathogenesis. LAM is an elegant model of malignancy because biallelic mutations at a single genetic locus confer all features that define cancer upon the LAM cell-metabolic reprogramming and proliferative signals that drive uncontrolled growth and inappropriate migration and invasion, the capacity to exploit the lymphatic circulation as a vehicle for metastasis and access to the lungs, and destruction of remote tissues. The direct benefit of the study of this rare disease has been the rapid identification of an effective FDA-approved therapy, and the collateral benefits have included elucidation of the pivotal roles of mTOR signaling in the regulation of cellular metabolism and the pathogenesis of cancer.
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Affiliation(s)
- Vera P Krymskaya
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Francis X McCormack
- Department of Internal Medicine, University of Cincinnati School of Medicine, Cincinnati, Ohio 45267;
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155
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Mantegazza AR, Wynosky-Dolfi MA, Casson CN, Lefkovith AJ, Shin S, Brodsky IE, Marks MS. Increased autophagic sequestration in adaptor protein-3 deficient dendritic cells limits inflammasome activity and impairs antibacterial immunity. PLoS Pathog 2017; 13:e1006785. [PMID: 29253868 PMCID: PMC5749898 DOI: 10.1371/journal.ppat.1006785] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Revised: 01/02/2018] [Accepted: 12/01/2017] [Indexed: 12/17/2022] Open
Abstract
Bacterial pathogens that compromise phagosomal membranes stimulate inflammasome assembly in the cytosol, but the molecular mechanisms by which membrane dynamics regulate inflammasome activity are poorly characterized. We show that in murine dendritic cells (DCs), the endosomal adaptor protein AP-3 –which optimizes toll-like receptor signaling from phagosomes–sustains inflammasome activation by particulate stimuli. AP-3 independently regulates inflammasome positioning and autophagy induction, together resulting in delayed inflammasome inactivation by autophagy in response to Salmonella Typhimurium (STm) and other particulate stimuli specifically in DCs. AP-3-deficient DCs, but not macrophages, hyposecrete IL-1β and IL-18 in response to particulate stimuli in vitro, but caspase-1 and IL-1β levels are restored by silencing autophagy. Concomitantly, AP-3-deficient mice exhibit higher mortality and produce less IL-1β, IL-18, and IL-17 than controls upon oral STm infection. Our data identify a novel link between phagocytosis, inflammasome activity and autophagy in DCs, potentially explaining impaired antibacterial immunity in AP-3-deficient patients. Bacterial uptake by phagocytic cells such as dendritic cells (DCs) stimulates signaling from membrane-bound toll-like receptors (TLRs) to shape adaptive immune responses. Pathogenic bacteria that damage phagocytic membranes additionally stimulate the cytoplasmic inflammasome, producing the highly inflammatory cytokines IL-1β and IL-18. Host molecular mechanisms that link phagosomal signaling to inflammasome regulation are poorly characterized. We show that in DCs, the endosomal adaptor protein-3 (AP-3) complex optimizes phagocytosis-induced inflammasome activity by two mechanisms: AP-3 promotes TLR signaling-dependent transcription of inflammasome components and antagonizes autophagy-dependent inflammasome silencing. Consequently, AP-3 deficient DCs hyposecrete IL-1β and IL-18 in response to phagocytosed stimuli, and AP-3 deficient mice succumb to infection by a bacterial pathogen. AP-3 thus links phagosome signaling, inflammasome activity and autophagy in DCs.
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Affiliation(s)
- Adriana R. Mantegazza
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia, Philadelphia, PA, United States of America
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States of America
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States of America
- * E-mail: (ARM); (MSM)
| | - Meghan A. Wynosky-Dolfi
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, United States of America
| | - Cierra N. Casson
- Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States of America
| | - Ariel J. Lefkovith
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia, Philadelphia, PA, United States of America
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States of America
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States of America
| | - Sunny Shin
- Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States of America
| | - Igor E. Brodsky
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, United States of America
| | - Michael S. Marks
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia, Philadelphia, PA, United States of America
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States of America
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States of America
- * E-mail: (ARM); (MSM)
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156
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Battu S, Minhas G, Mishra A, Khan N. Amino Acid Sensing via General Control Nonderepressible-2 Kinase and Immunological Programming. Front Immunol 2017; 8:1719. [PMID: 29321774 PMCID: PMC5732134 DOI: 10.3389/fimmu.2017.01719] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 11/21/2017] [Indexed: 12/16/2022] Open
Abstract
Metabolic adaptation to the changing nutrient levels in the cellular microenvironment plays a decisive role in the maintenance of homeostasis. Eukaryotic cells are equipped with nutrient sensors, which sense the fluctuating nutrients levels and accordingly program the cellular machinery to mount an appropriate response. Nutrients including amino acids play a vital role in maintaining cellular homeostasis. Therefore, over the evolution, different species have developed diverse mechanisms to detect amino acids abundance or scarcity. Immune responses have been known to be closely associated with the cellular metabolism especially amino acid sensing pathway, which influences innate as well as adaptive immune-effector functions. Thus, exploring the cross-talk between amino acid sensing mechanisms and immune responses in disease as well as in normal physiological conditions might open up avenues to explore how this association can be exploited to tailor immunological functions toward the design of better therapeutics for controlling metabolic diseases. In this review, we discuss the advances in the knowledge of various amino acid sensing pathways including general control nonderepressible-2 kinase in the control of inflammation and metabolic diseases.
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Affiliation(s)
- Srikanth Battu
- Department of Biotechnology and Bioinformatics, School of Life Sciences, University of Hyderabad, Hyderabad, India
| | - Gillipsie Minhas
- Department of Biomedical Engineering, IIT Hyderabad, Hyderabad, India
| | - Aman Mishra
- Department of Biotechnology and Bioinformatics, School of Life Sciences, University of Hyderabad, Hyderabad, India
| | - Nooruddin Khan
- Department of Biotechnology and Bioinformatics, School of Life Sciences, University of Hyderabad, Hyderabad, India
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157
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Cate JHD. Human eIF3: from 'blobology' to biological insight. Philos Trans R Soc Lond B Biol Sci 2017; 372:rstb.2016.0176. [PMID: 28138064 PMCID: PMC5311922 DOI: 10.1098/rstb.2016.0176] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/16/2016] [Indexed: 02/06/2023] Open
Abstract
Translation in eukaryotes is highly regulated during initiation, a process impacted by numerous readouts of a cell's state. There are many cases in which cellular messenger RNAs likely do not follow the canonical ‘scanning’ mechanism of translation initiation, but the molecular mechanisms underlying these pathways are still being uncovered. Some RNA viruses such as the hepatitis C virus use highly structured RNA elements termed internal ribosome entry sites (IRESs) that commandeer eukaryotic translation initiation, by using specific interactions with the general eukaryotic translation initiation factor eIF3. Here, I present evidence that, in addition to its general role in translation, eIF3 in humans and likely in all multicellular eukaryotes also acts as a translational activator or repressor by binding RNA structures in the 5′-untranslated regions of specific mRNAs, analogous to the role of the mediator complex in transcription. Furthermore, eIF3 in multicellular eukaryotes also harbours a 5′ 7-methylguanosine cap-binding subunit—eIF3d—which replaces the general cap-binding initiation factor eIF4E in the translation of select mRNAs. Based on results from cell biological, biochemical and structural studies of eIF3, it is likely that human translation initiation proceeds through dozens of different molecular pathways, the vast majority of which remain to be explored. This article is part of the themed issue ‘Perspectives on the ribosome’.
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Affiliation(s)
- Jamie H D Cate
- Departments of Chemistry and Molecular and Cell Biology, University of California, Berkeley, CA 94720-3220, USA .,Lawrence Berkeley National Laboratory, Division of Molecular Biophysics and Integrated Bioimaging, Berkeley, CA 94720, USA
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158
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Musso PY, Lampin-Saint-Amaux A, Tchenio P, Preat T. Ingestion of artificial sweeteners leads to caloric frustration memory in Drosophila. Nat Commun 2017; 8:1803. [PMID: 29180783 PMCID: PMC5703724 DOI: 10.1038/s41467-017-01989-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Accepted: 10/30/2017] [Indexed: 11/09/2022] Open
Abstract
Non-caloric artificial sweeteners (NAS) are widely used in modern human food, raising the question about their health impact. Here we have asked whether NAS consumption is a neutral experience at neural and behavioral level, or if NAS can be interpreted and remembered as negative experience. We used behavioral and imaging approaches to demonstrate that Drosophila melanogaster learn the non-caloric property of NAS through post-ingestion process. These results show that sweet taste is predictive of an energy value, and its absence leads to the formation of what we call Caloric Frustration Memory (CFM) that devalues the NAS or its caloric enantiomer. CFM formation involves activity of the associative memory brain structure, the mushroom bodies (MBs). In vivo calcium imaging of MB-input dopaminergic neurons that respond to sugar showed a reduced response to NAS after CFM formation. Altogether, these findings demonstrate that NAS are a negative experience for the brain. While non-caloric artificial sweeteners (NAS) are used as food additives, it’s unclear whether animals perceive NAS as positive or negative percept. Here, Musso and colleagues show in Drosophila that NAS is a negative percept, encoded in a new type of memory.
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Affiliation(s)
- Pierre-Yves Musso
- Genes and Dynamics of Memory Systems, Brain Plasticity Unit, CNRS, ESPCI Paris, PSL Research University, 75005, Paris, France.,Department of Zoology, Cell and Developmental Biology, University of British Columbia, Vancouver, BC, Canada, V6T 1Z3
| | - Aurélie Lampin-Saint-Amaux
- Genes and Dynamics of Memory Systems, Brain Plasticity Unit, CNRS, ESPCI Paris, PSL Research University, 75005, Paris, France
| | - Paul Tchenio
- Genes and Dynamics of Memory Systems, Brain Plasticity Unit, CNRS, ESPCI Paris, PSL Research University, 75005, Paris, France.,Laboratoire Aimé Cotton, CNRS, Université Paris-Sud, 91400, Orsay, France
| | - Thomas Preat
- Genes and Dynamics of Memory Systems, Brain Plasticity Unit, CNRS, ESPCI Paris, PSL Research University, 75005, Paris, France.
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159
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Yavari A, Bellahcene M, Bucchi A, Sirenko S, Pinter K, Herring N, Jung JJ, Tarasov KV, Sharpe EJ, Wolfien M, Czibik G, Steeples V, Ghaffari S, Nguyen C, Stockenhuber A, Clair JRS, Rimmbach C, Okamoto Y, Yang D, Wang M, Ziman BD, Moen JM, Riordon DR, Ramirez C, Paina M, Lee J, Zhang J, Ahmet I, Matt MG, Tarasova YS, Baban D, Sahgal N, Lockstone H, Puliyadi R, de Bono J, Siggs OM, Gomes J, Muskett H, Maguire ML, Beglov Y, Kelly M, Dos Santos PPN, Bright NJ, Woods A, Gehmlich K, Isackson H, Douglas G, Ferguson DJP, Schneider JE, Tinker A, Wolkenhauer O, Channon KM, Cornall RJ, Sternick EB, Paterson DJ, Redwood CS, Carling D, Proenza C, David R, Baruscotti M, DiFrancesco D, Lakatta EG, Watkins H, Ashrafian H. Mammalian γ2 AMPK regulates intrinsic heart rate. Nat Commun 2017; 8:1258. [PMID: 29097735 PMCID: PMC5668267 DOI: 10.1038/s41467-017-01342-5] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Accepted: 09/08/2017] [Indexed: 11/22/2022] Open
Abstract
AMPK is a conserved serine/threonine kinase whose activity maintains cellular energy homeostasis. Eukaryotic AMPK exists as αβγ complexes, whose regulatory γ subunit confers energy sensor function by binding adenine nucleotides. Humans bearing activating mutations in the γ2 subunit exhibit a phenotype including unexplained slowing of heart rate (bradycardia). Here, we show that γ2 AMPK activation downregulates fundamental sinoatrial cell pacemaker mechanisms to lower heart rate, including sarcolemmal hyperpolarization-activated current (I f) and ryanodine receptor-derived diastolic local subsarcolemmal Ca2+ release. In contrast, loss of γ2 AMPK induces a reciprocal phenotype of increased heart rate, and prevents the adaptive intrinsic bradycardia of endurance training. Our results reveal that in mammals, for which heart rate is a key determinant of cardiac energy demand, AMPK functions in an organ-specific manner to maintain cardiac energy homeostasis and determines cardiac physiological adaptation to exercise by modulating intrinsic sinoatrial cell behavior.
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Affiliation(s)
- Arash Yavari
- Experimental Therapeutics, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK.
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK.
- The Wellcome Trust Centre for Human Genetics, Oxford, OX3 7BN, UK.
| | - Mohamed Bellahcene
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK
- The Wellcome Trust Centre for Human Genetics, Oxford, OX3 7BN, UK
| | - Annalisa Bucchi
- Department of Biosciences, Università degli Studi di Milano, Milan, 20133, Italy
- Centro Interuniversitario di Medicina Molecolare e Biofisica Applicata, University of Milano, Milan, 20133, Italy
| | - Syevda Sirenko
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, NIH, Baltimore, MD, 21224, USA
| | - Katalin Pinter
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK
- The Wellcome Trust Centre for Human Genetics, Oxford, OX3 7BN, UK
| | - Neil Herring
- Burdon Sanderson Cardiac Science Centre, Department of Physiology, Anatomy & Genetics, University of Oxford, Oxford, OX1 3PT, UK
| | - Julia J Jung
- Department of Cardiac Surgery, Rostock University Medical Centre, 18057, Rostock, Germany
- Department Life, Light and Matter, Interdisciplinary Faculty, Rostock University, 18059, Rostock, Germany
| | - Kirill V Tarasov
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, NIH, Baltimore, MD, 21224, USA
| | - Emily J Sharpe
- Department of Physiology and Biophysics, University of Colorado School of Medicine, Aurora, CO, 80045, USA
| | - Markus Wolfien
- Department of Systems Biology and Bioinformatics, University of Rostock, Rostock, 18051, Germany
| | - Gabor Czibik
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK
- The Wellcome Trust Centre for Human Genetics, Oxford, OX3 7BN, UK
| | - Violetta Steeples
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK
- The Wellcome Trust Centre for Human Genetics, Oxford, OX3 7BN, UK
| | - Sahar Ghaffari
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK
- The Wellcome Trust Centre for Human Genetics, Oxford, OX3 7BN, UK
| | - Chinh Nguyen
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK
- The Wellcome Trust Centre for Human Genetics, Oxford, OX3 7BN, UK
| | - Alexander Stockenhuber
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK
- The Wellcome Trust Centre for Human Genetics, Oxford, OX3 7BN, UK
| | - Joshua R St Clair
- Department of Physiology and Biophysics, University of Colorado School of Medicine, Aurora, CO, 80045, USA
| | - Christian Rimmbach
- Department of Cardiac Surgery, Rostock University Medical Centre, 18057, Rostock, Germany
- Department Life, Light and Matter, Interdisciplinary Faculty, Rostock University, 18059, Rostock, Germany
| | - Yosuke Okamoto
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, NIH, Baltimore, MD, 21224, USA
| | - Dongmei Yang
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, NIH, Baltimore, MD, 21224, USA
| | - Mingyi Wang
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, NIH, Baltimore, MD, 21224, USA
| | - Bruce D Ziman
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, NIH, Baltimore, MD, 21224, USA
| | - Jack M Moen
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, NIH, Baltimore, MD, 21224, USA
| | - Daniel R Riordon
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, NIH, Baltimore, MD, 21224, USA
| | - Christopher Ramirez
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, NIH, Baltimore, MD, 21224, USA
| | - Manuel Paina
- Department of Biosciences, Università degli Studi di Milano, Milan, 20133, Italy
- Centro Interuniversitario di Medicina Molecolare e Biofisica Applicata, University of Milano, Milan, 20133, Italy
| | - Joonho Lee
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, NIH, Baltimore, MD, 21224, USA
| | - Jing Zhang
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, NIH, Baltimore, MD, 21224, USA
| | - Ismayil Ahmet
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, NIH, Baltimore, MD, 21224, USA
| | - Michael G Matt
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, NIH, Baltimore, MD, 21224, USA
| | - Yelena S Tarasova
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, NIH, Baltimore, MD, 21224, USA
| | - Dilair Baban
- The Wellcome Trust Centre for Human Genetics, Oxford, OX3 7BN, UK
| | - Natasha Sahgal
- The Wellcome Trust Centre for Human Genetics, Oxford, OX3 7BN, UK
| | - Helen Lockstone
- The Wellcome Trust Centre for Human Genetics, Oxford, OX3 7BN, UK
| | - Rathi Puliyadi
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK
- The Wellcome Trust Centre for Human Genetics, Oxford, OX3 7BN, UK
| | - Joseph de Bono
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK
- The Wellcome Trust Centre for Human Genetics, Oxford, OX3 7BN, UK
| | - Owen M Siggs
- The Wellcome Trust Centre for Human Genetics, Oxford, OX3 7BN, UK
- MRC Human Immunology Unit, Weatherall Institute for Molecular Medicine, Nuffield Department of Medicine, University of Oxford, Oxford, OX3 9DS, UK
| | - John Gomes
- Department of Medicine, BHF Laboratories, The Rayne Institute, University College London, London, WC1E 6JJ, UK
| | - Hannah Muskett
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK
- The Wellcome Trust Centre for Human Genetics, Oxford, OX3 7BN, UK
| | - Mahon L Maguire
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK
- The Wellcome Trust Centre for Human Genetics, Oxford, OX3 7BN, UK
| | - Youlia Beglov
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK
- The Wellcome Trust Centre for Human Genetics, Oxford, OX3 7BN, UK
| | - Matthew Kelly
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK
- The Wellcome Trust Centre for Human Genetics, Oxford, OX3 7BN, UK
| | - Pedro P N Dos Santos
- Instituto de Pós-Graduação, Faculdade de Ciências Médicas de Minas Gerais, Belo Horizonte, 30.130-110, Brazil
| | - Nicola J Bright
- Cellular Stress Group, MRC London Institute of Medical Sciences, Imperial College London, London, W12 0NN, UK
| | - Angela Woods
- Cellular Stress Group, MRC London Institute of Medical Sciences, Imperial College London, London, W12 0NN, UK
| | - Katja Gehmlich
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK
- The Wellcome Trust Centre for Human Genetics, Oxford, OX3 7BN, UK
| | - Henrik Isackson
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK
| | - Gillian Douglas
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK
- The Wellcome Trust Centre for Human Genetics, Oxford, OX3 7BN, UK
| | - David J P Ferguson
- Nuffield Department of Clinical Laboratory Science, University of Oxford, Oxford, OX3 9DU, UK
| | - Jürgen E Schneider
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK
- The Wellcome Trust Centre for Human Genetics, Oxford, OX3 7BN, UK
| | - Andrew Tinker
- Department of Medicine, BHF Laboratories, The Rayne Institute, University College London, London, WC1E 6JJ, UK
- The Heart Centre, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, London, EC1M 6BQ, UK
| | - Olaf Wolkenhauer
- Department of Systems Biology and Bioinformatics, University of Rostock, Rostock, 18051, Germany
- Stellenbosch Institute of Advanced Study (STIAS), Wallenberg Research Centre at Stellenbosch University, Stellenbosch, 7602, South Africa
| | - Keith M Channon
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK
- The Wellcome Trust Centre for Human Genetics, Oxford, OX3 7BN, UK
| | - Richard J Cornall
- The Wellcome Trust Centre for Human Genetics, Oxford, OX3 7BN, UK
- MRC Human Immunology Unit, Weatherall Institute for Molecular Medicine, Nuffield Department of Medicine, University of Oxford, Oxford, OX3 9DS, UK
| | - Eduardo B Sternick
- Instituto de Pós-Graduação, Faculdade de Ciências Médicas de Minas Gerais, Belo Horizonte, 30.130-110, Brazil
| | - David J Paterson
- Burdon Sanderson Cardiac Science Centre, Department of Physiology, Anatomy & Genetics, University of Oxford, Oxford, OX1 3PT, UK
| | - Charles S Redwood
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK
| | - David Carling
- Cellular Stress Group, MRC London Institute of Medical Sciences, Imperial College London, London, W12 0NN, UK
| | - Catherine Proenza
- Department of Physiology and Biophysics, University of Colorado School of Medicine, Aurora, CO, 80045, USA
| | - Robert David
- Department of Cardiac Surgery, Rostock University Medical Centre, 18057, Rostock, Germany
- Department Life, Light and Matter, Interdisciplinary Faculty, Rostock University, 18059, Rostock, Germany
| | - Mirko Baruscotti
- Department of Biosciences, Università degli Studi di Milano, Milan, 20133, Italy
- Centro Interuniversitario di Medicina Molecolare e Biofisica Applicata, University of Milano, Milan, 20133, Italy
| | - Dario DiFrancesco
- Department of Biosciences, Università degli Studi di Milano, Milan, 20133, Italy
- Centro Interuniversitario di Medicina Molecolare e Biofisica Applicata, University of Milano, Milan, 20133, Italy
| | - Edward G Lakatta
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, NIH, Baltimore, MD, 21224, USA
| | - Hugh Watkins
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK
- The Wellcome Trust Centre for Human Genetics, Oxford, OX3 7BN, UK
| | - Houman Ashrafian
- Experimental Therapeutics, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK.
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DU, UK.
- The Wellcome Trust Centre for Human Genetics, Oxford, OX3 7BN, UK.
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160
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Abstract
In this issue of Molecular Cell, Moloughney et al. (2016) find that mTORC2 responds to falling levels of glucose and glutamine catabolites, promoting glutaminolysis and preserving the TCA cycle and hexosamine biosynthesis.
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Affiliation(s)
- Sebastian I Arriola Apelo
- Department of Medicine, University of Wisconsin-Madison and William S. Middleton Memorial Veterans Hospital, Madison, WI 53705, USA
| | - Dudley W Lamming
- Department of Medicine, University of Wisconsin-Madison and William S. Middleton Memorial Veterans Hospital, Madison, WI 53705, USA.
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161
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Palm W, Thompson CB. Nutrient acquisition strategies of mammalian cells. Nature 2017; 546:234-242. [PMID: 28593971 DOI: 10.1038/nature22379] [Citation(s) in RCA: 259] [Impact Index Per Article: 37.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Accepted: 04/21/2017] [Indexed: 12/14/2022]
Abstract
Mammalian cells are surrounded by diverse nutrients, such as glucose, amino acids, various macromolecules and micronutrients, which they can import through transmembrane transporters and endolysosomal pathways. By using different nutrient sources, cells gain metabolic flexibility to survive periods of starvation. Quiescent cells take up sufficient nutrients to sustain homeostasis. However, proliferating cells depend on growth-factor-induced increases in nutrient uptake to support biomass formation. Here, we review cellular nutrient acquisition strategies and their regulation by growth factors and cell-intrinsic nutrient sensors. We also discuss how oncogenes and tumour suppressors promote nutrient uptake and thereby support the survival and growth of cancer cells.
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Affiliation(s)
- Wilhelm Palm
- Cancer Biology and Genetics Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA
| | - Craig B Thompson
- Cancer Biology and Genetics Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA
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162
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DGAT1-Dependent Lipid Droplet Biogenesis Protects Mitochondrial Function during Starvation-Induced Autophagy. Dev Cell 2017; 42:9-21.e5. [PMID: 28697336 DOI: 10.1016/j.devcel.2017.06.003] [Citation(s) in RCA: 323] [Impact Index Per Article: 46.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Revised: 04/25/2017] [Accepted: 06/02/2017] [Indexed: 01/22/2023]
Abstract
Lipid droplets (LDs) provide an "on-demand" source of fatty acids (FAs) that can be mobilized in response to fluctuations in nutrient abundance. Surprisingly, the amount of LDs increases during prolonged periods of nutrient deprivation. Why cells store FAs in LDs during an energy crisis is unknown. Our data demonstrate that mTORC1-regulated autophagy is necessary and sufficient for starvation-induced LD biogenesis. The ER-resident diacylglycerol acyltransferase 1 (DGAT1) selectively channels autophagy-liberated FAs into new, clustered LDs that are in close proximity to mitochondria and are lipolytically degraded. However, LDs are not required for FA delivery to mitochondria but instead function to prevent acylcarnitine accumulation and lipotoxic dysregulation of mitochondria. Our data support a model in which LDs provide a lipid buffering system that sequesters FAs released during the autophagic degradation of membranous organelles, reducing lipotoxicity. These findings reveal an unrecognized aspect of the cellular adaptive response to starvation, mediated by LDs.
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163
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Abstract
The evolution of a nervous system as a control system of the body's functions is a key innovation of animals. Its fundamental units are neurons, highly specialized cells dedicated to fast cell-cell communication. Neurons pass signals to other neurons, muscle cells, or gland cells at specialized junctions, the synapses, where transmitters are released from vesicles in a Ca2+-dependent fashion to activate receptors in the membrane of the target cell. Reconstructing the origins of neuronal communication out of a more simple process remains a central challenge in biology. Recent genomic comparisons have revealed that all animals, including the nerveless poriferans and placozoans, share a basic set of genes for neuronal communication. This suggests that the first animal, the Urmetazoan, was already endowed with neurosecretory cells that probably started to connect into neuronal networks soon afterward. Here, we discuss scenarios for this pivotal transition in animal evolution.
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Affiliation(s)
- Frederique Varoqueaux
- Département des Neurosciences Fondamentales, Université de Lausanne, Lausanne, CH-1005 Switzerland; ,
| | - Dirk Fasshauer
- Département des Neurosciences Fondamentales, Université de Lausanne, Lausanne, CH-1005 Switzerland; ,
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164
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Wang Y, Guo Z, Liu M, Zhao K, Feng X, Zheng X, Wang X, Hao H, Guo X, Wang Z. Proteasome subunit beta type 1 interacts directly with Rheb and regulates the cell cycle in Cashmere goat fetal fibroblasts. Anim Cells Syst (Seoul) 2017. [DOI: 10.1080/19768354.2017.1371072] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Affiliation(s)
- Yanfeng Wang
- Inner Mongolia Key Laboratory for Molecular Regulation of the Cell, College of Life Sciences, Inner Mongolia University, Hohhot, People’s Republic of China
| | - Zhixin Guo
- Inner Mongolia Key Laboratory for Molecular Regulation of the Cell, College of Life Sciences, Inner Mongolia University, Hohhot, People’s Republic of China
| | - Mingtao Liu
- Inner Mongolia Key Laboratory for Molecular Regulation of the Cell, College of Life Sciences, Inner Mongolia University, Hohhot, People’s Republic of China
| | - Keyu Zhao
- Inner Mongolia Key Laboratory for Molecular Regulation of the Cell, College of Life Sciences, Inner Mongolia University, Hohhot, People’s Republic of China
| | - Xue Feng
- Inner Mongolia Key Laboratory for Molecular Regulation of the Cell, College of Life Sciences, Inner Mongolia University, Hohhot, People’s Republic of China
| | - Xu Zheng
- Inner Mongolia Key Laboratory for Molecular Regulation of the Cell, College of Life Sciences, Inner Mongolia University, Hohhot, People’s Republic of China
- Department of Clinical Laboratory, Hulunbeir Municipal People’s Hospital, Hailar, People’s Republic of China
| | - Xiaojing Wang
- Inner Mongolia Key Laboratory for Molecular Regulation of the Cell, College of Life Sciences, Inner Mongolia University, Hohhot, People’s Republic of China
- Department of Clinical Laboratory, Chifeng Municipal Hospital, Chifeng, People’s Republic of China
| | - Huifang Hao
- Inner Mongolia Key Laboratory for Molecular Regulation of the Cell, College of Life Sciences, Inner Mongolia University, Hohhot, People’s Republic of China
| | - Xudong Guo
- Inner Mongolia Key Laboratory for Molecular Regulation of the Cell, College of Life Sciences, Inner Mongolia University, Hohhot, People’s Republic of China
| | - Zhigang Wang
- Inner Mongolia Key Laboratory for Molecular Regulation of the Cell, College of Life Sciences, Inner Mongolia University, Hohhot, People’s Republic of China
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165
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Romero R, Erez O, Hüttemann M, Maymon E, Panaitescu B, Conde-Agudelo A, Pacora P, Yoon BH, Grossman LI. Metformin, the aspirin of the 21st century: its role in gestational diabetes mellitus, prevention of preeclampsia and cancer, and the promotion of longevity. Am J Obstet Gynecol 2017; 217:282-302. [PMID: 28619690 DOI: 10.1016/j.ajog.2017.06.003] [Citation(s) in RCA: 152] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Revised: 05/30/2017] [Accepted: 06/05/2017] [Indexed: 12/16/2022]
Abstract
Metformin is everywhere. Originally introduced in clinical practice as an antidiabetic agent, its role as a therapeutic agent is expanding to include treatment of prediabetes mellitus, gestational diabetes mellitus, and polycystic ovarian disease; more recently, experimental studies and observations in randomized clinical trials suggest that metformin could have a place in the treatment or prevention of preeclampsia. This article provides a brief overview of the history of metformin in the treatment of diabetes mellitus and reviews the results of metaanalyses of metformin in gestational diabetes mellitus as well as the treatment of obese, non-diabetic, pregnant women to prevent macrosomia. We highlight the results of a randomized clinical trial in which metformin administration in early pregnancy did not reduce the frequency of large-for-gestational-age infants (the primary endpoint) but did decrease the frequency of preeclampsia (a secondary endpoint). The mechanisms by which metformin may prevent preeclampsia include a reduction in the production of antiangiogenic factors (soluble vascular endothelial growth factor receptor-1 and soluble endoglin) and the improvement of endothelial dysfunction, probably through an effect on the mitochondria. Another potential mechanism whereby metformin may play a role in the prevention of preeclampsia is its ability to modify cellular homeostasis and energy disposition, mediated by rapamycin, a mechanistic target. Metformin has a molecular weight of 129 Daltons and therefore readily crosses the placenta. There is considerable evidence to suggest that this agent is safe during pregnancy. New literature on the role of metformin as a chemotherapeutic adjuvant in the prevention of cancer and in prolonging life and protecting against aging is reviewed briefly. Herein, we discuss the mechanisms of action and potential benefits of metformin.
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166
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Abstract
All organisms can respond to the availability of nutrients by regulating their metabolism, growth, and cell division. Central to the regulation of growth in response to nutrient availability is the target of rapamycin (TOR) signaling that is composed of two structurally distinct complexes: TOR complex 1 (TORC1) and TOR complex 2 (TORC2). The TOR genes were first identified in yeast as target of rapamycin, a natural product of a soil bacterium, which proved beneficial as an immunosuppressive and anticancer drug and is currently being tested for a handful of other pathological conditions including diabetes, neurodegeneration, and age-related diseases. Studies of the TOR pathway unraveled a complex growth-regulating network. TOR regulates nutrient uptake, transcription, protein synthesis and degradation, as well as metabolic pathways, in a coordinated manner that ensures that cells grow or cease growth in response to nutrient availability. The identification of specific signals and mechanisms that stimulate TOR signaling is an active and exciting field of research that has already identified nitrogen and amino acids as key regulators of TORC1 activity. The signals, as well as the cellular functions of TORC2, are far less well understood. Additional open questions in the field concern the relationships between TORC1 and TORC2, as well as the links with other nutrient-responsive pathways. Here I review the main features of TORC1 and TORC2, with a particular focus on yeasts as model organisms.
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167
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Abstract
Fungi are able to switch between different lifestyles in order to adapt to environmental changes. Their ecological strategy is connected to their secretome as fungi obtain nutrients by secreting hydrolytic enzymes to their surrounding and acquiring the digested molecules. We focus on fungal serine proteases (SPs), the phylogenetic distribution of which is barely described so far. In order to collect a complete set of fungal proteases, we searched over 600 fungal proteomes. Obtained results suggest that serine proteases are more ubiquitous than expected. From 54 SP families described in MEROPS Peptidase Database, 21 are present in fungi. Interestingly, 14 of them are also present in Metazoa and Viridiplantae - this suggests that, except one (S64), all fungal SP families evolved before plants and fungi diverged. Most representatives of sequenced eukaryotic lineages encode a set of 13-16 SP families. The number of SPs from each family varies among the analysed taxa. The most abundant are S8 proteases. In order to verify hypotheses linking lifestyle and expansions of particular SP, we performed statistical analyses and revealed previously undescribed associations. Here, we present a comprehensive evolutionary history of fungal SP families in the context of fungal ecology and fungal tree of life.
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168
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Sipe CW, Siegrist SE. Eyeless uncouples mushroom body neuroblast proliferation from dietary amino acids in Drosophila. eLife 2017; 6:26343. [PMID: 28826476 PMCID: PMC5576483 DOI: 10.7554/elife.26343] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Accepted: 08/08/2017] [Indexed: 11/13/2022] Open
Abstract
Cell proliferation is coupled with nutrient availability. If nutrients become limited, proliferation ceases, because growth factor and/or PI3-kinase activity levels become attenuated. Here, we report an exception to this generality within a subpopulation of Drosophila neural stem cells (neuroblasts). We find that most neuroblasts enter and exit cell cycle in a nutrient-dependent manner that is reversible and regulated by PI3-kinase. However, a small subset, the mushroom body neuroblasts, which generate neurons important for memory and learning, divide independent of dietary nutrient conditions and PI3-kinase activity. This nutrient-independent proliferation is regulated by Eyeless, a Pax-6 orthologue, expressed in mushroom body neuroblasts. When Eyeless is knocked down, mushroom body neuroblasts exit cell cycle when nutrients are withdrawn. Conversely, when Eyeless is ectopically expressed, some non-mushroom body neuroblasts divide independent of dietary nutrient conditions. Therefore, Eyeless uncouples MB neuroblast proliferation from nutrient availability, allowing preferential neurogenesis in brain subregions during nutrient poor conditions.
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Affiliation(s)
- Conor W Sipe
- Department of Biology, University of Virginia, Charlottesville, United States
| | - Sarah E Siegrist
- Department of Biology, University of Virginia, Charlottesville, United States
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169
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Wolfson RL, Sabatini DM. The Dawn of the Age of Amino Acid Sensors for the mTORC1 Pathway. Cell Metab 2017; 26:301-309. [PMID: 28768171 PMCID: PMC5560103 DOI: 10.1016/j.cmet.2017.07.001] [Citation(s) in RCA: 382] [Impact Index Per Article: 54.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/21/2017] [Revised: 06/27/2017] [Accepted: 07/06/2017] [Indexed: 01/19/2023]
Abstract
The mechanistic target of rapamycin complex 1 (mTORC1) is a master regulator of cell growth that responds to a diverse set of environmental inputs, including amino acids. Over the past 10 years, a number of proteins have been identified that help transmit amino acid availability to mTORC1. However, amino acid sensors for this pathway have only recently been discovered. Here, we review these recent advances and highlight the variety of unexplored questions that emerge from the identification of these sensors.
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Affiliation(s)
- Rachel L Wolfson
- Whitehead Institute for Biomedical Research, 455 Main Street, Cambridge, MA 02142, USA; Department of Biology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA; Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA; Koch Institute for Integrative Cancer Research at MIT, 77 Massachusetts Avenue, Cambridge, MA 02139, USA; Broad Institute, 415 Main Street, Cambridge, MA 02142, USA
| | - David M Sabatini
- Whitehead Institute for Biomedical Research, 455 Main Street, Cambridge, MA 02142, USA; Department of Biology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA; Howard Hughes Medical Institute, Department of Biology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA; Koch Institute for Integrative Cancer Research at MIT, 77 Massachusetts Avenue, Cambridge, MA 02139, USA; Broad Institute, 415 Main Street, Cambridge, MA 02142, USA.
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170
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Mancio-Silva L, Slavic K, Grilo Ruivo MT, Grosso AR, Modrzynska KK, Vera IM, Sales-Dias J, Gomes AR, MacPherson CR, Crozet P, Adamo M, Baena-Gonzalez E, Tewari R, Llinás M, Billker O, Mota MM. Nutrient sensing modulates malaria parasite virulence. Nature 2017; 547:213-216. [PMID: 28678779 PMCID: PMC5511512 DOI: 10.1038/nature23009] [Citation(s) in RCA: 118] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Accepted: 05/19/2017] [Indexed: 01/06/2023]
Abstract
The lifestyle of intracellular pathogens, such as malaria parasites, is intimately connected to that of their host, primarily for nutrient supply. Nutrients act not only as primary sources of energy but also as regulators of gene expression, metabolism and growth, through various signalling networks that enable cells to sense and adapt to varying environmental conditions. Canonical nutrient-sensing pathways are presumed to be absent from the causative agent of malaria, Plasmodium, thus raising the question of whether these parasites can sense and cope with fluctuations in host nutrient levels. Here we show that Plasmodium blood-stage parasites actively respond to host dietary calorie alterations through rearrangement of their transcriptome accompanied by substantial adjustment of their multiplication rate. A kinome analysis combined with chemical and genetic approaches identified KIN as a critical regulator that mediates sensing of nutrients and controls a transcriptional response to the host nutritional status. KIN shares homology with SNF1/AMPKα, and yeast complementation studies suggest that it is part of a functionally conserved cellular energy-sensing pathway. Overall, these findings reveal a key parasite nutrient-sensing mechanism that is critical for modulating parasite replication and virulence.
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Affiliation(s)
- Liliana Mancio-Silva
- Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, 1649-028 Lisboa, Portugal
| | - Ksenija Slavic
- Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, 1649-028 Lisboa, Portugal
| | - Margarida T. Grilo Ruivo
- Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, 1649-028 Lisboa, Portugal
| | - Ana Rita Grosso
- Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, 1649-028 Lisboa, Portugal
| | | | - Iset Medina Vera
- Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, 1649-028 Lisboa, Portugal
| | - Joana Sales-Dias
- Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, 1649-028 Lisboa, Portugal
| | - Ana Rita Gomes
- Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, UK
| | | | | | - Mattia Adamo
- Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | | | - Rita Tewari
- School of Life Sciences, Queens Medical Centre, University of Nottingham, Nottingham, UK
| | - Manuel Llinás
- Department of Biochemistry and Molecular Biology, Department of Chemistry, Center for Malaria Research, and Center for Infectious Disease Dynamics, The Pennsylvania State University, State College, Pennsylvania 16802, USA
| | - Oliver Billker
- Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, UK
| | - Maria M. Mota
- Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, 1649-028 Lisboa, Portugal
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171
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Dinkeloo K, Boyd S, Pilot G. Update on amino acid transporter functions and on possible amino acid sensing mechanisms in plants. Semin Cell Dev Biol 2017; 74:105-113. [PMID: 28705659 DOI: 10.1016/j.semcdb.2017.07.010] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Revised: 06/30/2017] [Accepted: 07/07/2017] [Indexed: 12/25/2022]
Abstract
Amino acids are essential components of plant metabolism, not only as constituents of proteins, but also as precursors of important secondary metabolites and as carriers of organic nitrogen between the organs of the plant. Transport across intracellular membranes and translocation of amino acids within the plant is mediated by membrane amino acid transporters. The past few years have seen the identification of a new family of amino acid transporters in Arabidopsis, the characterization of intracellular amino acid transporters, and the discovery of new roles for already known proteins. While amino acid metabolism needs to be tightly coordinated with amino acid transport activity and carbohydrate metabolism, no gene involved in amino acid sensing in plants has been unequivocally identified to date. This review aims at summarizing the recent data accumulated on the identity and function of amino acid transporters in plants, and discussing the possible identity of amino acid sensors based on data from other organisms.
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Affiliation(s)
- Kasia Dinkeloo
- Department of Plant Pathology, Physiology and Weed Science, Virginia Tech, Blacksburg, VA 24060, USA
| | - Shelton Boyd
- Department of Plant Pathology, Physiology and Weed Science, Virginia Tech, Blacksburg, VA 24060, USA
| | - Guillaume Pilot
- Department of Plant Pathology, Physiology and Weed Science, Virginia Tech, Blacksburg, VA 24060, USA.
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172
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The Architecture of the Rag GTPase Signaling Network. Biomolecules 2017; 7:biom7030048. [PMID: 28788436 PMCID: PMC5618229 DOI: 10.3390/biom7030048] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Revised: 06/22/2017] [Accepted: 06/27/2017] [Indexed: 12/11/2022] Open
Abstract
The evolutionarily conserved target of rapamycin complex 1 (TORC1) couples an array of intra- and extracellular stimuli to cell growth, proliferation and metabolism, and its deregulation is associated with various human pathologies such as immunodeficiency, epilepsy, and cancer. Among the diverse stimuli impinging on TORC1, amino acids represent essential input signals, but how they control TORC1 has long remained a mystery. The recent discovery of the Rag GTPases, which assemble as heterodimeric complexes on vacuolar/lysosomal membranes, as central elements of an amino acid signaling network upstream of TORC1 in yeast, flies, and mammalian cells represented a breakthrough in this field. Here, we review the architecture of the Rag GTPase signaling network with a special focus on structural aspects of the Rag GTPases and their regulators in yeast and highlight both the evolutionary conservation and divergence of the mechanisms that control Rag GTPases.
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173
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Graber TG, Borack MS, Reidy PT, Volpi E, Rasmussen BB. Essential amino acid ingestion alters expression of genes associated with amino acid sensing, transport, and mTORC1 regulation in human skeletal muscle. Nutr Metab (Lond) 2017; 14:35. [PMID: 28503190 PMCID: PMC5426042 DOI: 10.1186/s12986-017-0187-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Accepted: 05/01/2017] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND Amino acid availability stimulates protein synthesis via the mTORC1 (mechanistic target of rapamycin complex 1) signaling pathway. In response to an increase in cellular amino acid availability, translocation of cytosolic mTORC1 to the lysosomal surface is required to stimulate mTORC1 kinase activity. However, research elucidating the amino acid responsive mechanisms have thus far only been conducted in in vitro models. Our primary objective was to determine whether an increase in amino acid availability within human skeletal muscle in vivo would alter the expression of genes associated with amino acid sensing, transport and mTORC1 regulation. Our secondary objective was to determine whether an acute perturbation in lysosomal function would disrupt the normal pattern of muscle amino acid responsive gene expression. METHODS We recruited 13 young adults into one of two groups: The first group ingested 10 g of essential amino acids (EAA). The second group ingested 10 g of EAA in the presence of chloroquine (CQ), a lysosomotropic agent. The subjects from each group had biopsies of the vastus lateralis taken before and after EAA ingestion. We determined the relative mRNA expression of 51 potential amino acid responsive genes using RT-qPCR. RESULTS There was a differential mRNA expression for 22 genes, with 15 mRNAs significantly changing (P < 0.05) in response to EAA ingestion (e.g., REDD1: +209 ± 35%; SLC38A9: +31 ± 9%; SLC38A10: +57 ± 15%). In the CQ group, EAA ingestion resulted in a differential expression as compared to EAA alone (i.e., 11 out of the 22 genes were different (P < 0.05) between the two groups.). CONCLUSIONS Expression of several amino acid sensing, transport, and mTORC1 regulatory genes in human skeletal muscle are responsive to an increase in amino acid availability. Furthermore, potential acute disruption of lysosomal function by ingestion of chloroquine interferes with the normal pattern of gene expression following feeding. Our in vivo data in humans provide preliminary support for the in vitro work linking amino acid sensing pathways to mTORC1 translocation to the lysosome. TRIAL REGISTRATION NCT00891696. Registered 29 April 2009.
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Affiliation(s)
- Ted G. Graber
- Division of Rehabilitation Sciences, University of Texas Medical Branch, 301 University Blvd, Galveston, TX 77555-1124 USA
| | - Michael S. Borack
- Division of Rehabilitation Sciences, University of Texas Medical Branch, 301 University Blvd, Galveston, TX 77555-1124 USA
| | - Paul T. Reidy
- Division of Rehabilitation Sciences, University of Texas Medical Branch, 301 University Blvd, Galveston, TX 77555-1124 USA
- Present Address: Department of Physical Therapy, University of Utah, Salt Lake City, Utah USA
| | - Elena Volpi
- Department of Internal Medicine – Geriatrics, University of Texas Medical Branch, 301 University Blvd, Galveston, TX 77555-1124 USA
| | - Blake B. Rasmussen
- Department of Nutrition and Metabolism, University of Texas Medical Branch, 301 University Blvd, Galveston, TX 77555-1124 USA
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174
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Michel AH, Hatakeyama R, Kimmig P, Arter M, Peter M, Matos J, De Virgilio C, Kornmann B. Functional mapping of yeast genomes by saturated transposition. eLife 2017; 6. [PMID: 28481201 PMCID: PMC5466422 DOI: 10.7554/elife.23570] [Citation(s) in RCA: 89] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Accepted: 05/06/2017] [Indexed: 12/17/2022] Open
Abstract
Yeast is a powerful model for systems genetics. We present a versatile, time- and labor-efficient method to functionally explore the Saccharomyces cerevisiae genome using saturated transposon mutagenesis coupled to high-throughput sequencing. SAturated Transposon Analysis in Yeast (SATAY) allows one-step mapping of all genetic loci in which transposons can insert without disrupting essential functions. SATAY is particularly suited to discover loci important for growth under various conditions. SATAY (1) reveals positive and negative genetic interactions in single and multiple mutant strains, (2) can identify drug targets, (3) detects not only essential genes, but also essential protein domains, (4) generates both null and other informative alleles. In a SATAY screen for rapamycin-resistant mutants, we identify Pib2 (PhosphoInositide-Binding 2) as a master regulator of TORC1. We describe two antagonistic TORC1-activating and -inhibiting activities located on opposite ends of Pib2. Thus, SATAY allows to easily explore the yeast genome at unprecedented resolution and throughput. DOI:http://dx.doi.org/10.7554/eLife.23570.001 Genes are stretches of DNA that carry the instructions to build and maintain cells. Many studies in genetics involve inactivating one or more genes and observing the consequences. If the loss of a gene kills the cell, that gene is likely to be vital for life. If it does not, the gene may not be essential, or a similar gene may be able to take over its role. Baker’s yeast is a simple organism that shares many characteristics with human cells. Many yeast genes have a counterpart among human genes, and so studying baker’s yeast can reveal clues about our own genetics. Michel et al. report an adaptation for baker’s yeast of a technique called “Transposon sequencing”, which had been used in other single-celled organisms to study the effects of interrupting genes. Briefly, a virus-like piece of DNA, called a transposon, inserts randomly into the genetic material and switches off individual genes. The DNA is then sequenced to reveal every gene that can be disrupted without killing the cell, and remaining genes are inferred to be essential for life. The approach, named SATAY (which is short for “saturated transposon analysis in yeast”), uses this strategy to create millions of baker’s yeast cells, each with a different gene switched off. Because the number of cells generated this way vastly exceeds the number of genes, every gene will be switched off by several independent transposons. Therefore the technique allows all yeast genes to be inactivated several times in one single experiment. The cells can be grown in varying conditions during the experiment, revealing the genes needed for survival in different situations. Non-essential genes can also be inactivated beforehand to uncover if any genes might be compensating for their absence. In the future, this technique may be used to better understand human diseases, such as cancer, since many disease-causing genes in humans have counterparts in yeast. DOI:http://dx.doi.org/10.7554/eLife.23570.002
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Affiliation(s)
- Agnès H Michel
- Institute of Biochemistry, ETH Zurich, Zurich, Switzerland
| | - Riko Hatakeyama
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Philipp Kimmig
- Institute of Biochemistry, ETH Zurich, Zurich, Switzerland
| | - Meret Arter
- Institute of Biochemistry, ETH Zurich, Zurich, Switzerland
| | - Matthias Peter
- Institute of Biochemistry, ETH Zurich, Zurich, Switzerland
| | - Joao Matos
- Institute of Biochemistry, ETH Zurich, Zurich, Switzerland
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175
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Abstract
The primary processes that contribute to the efficient capture of soil nitrate are the development of a root system that effectively explores the soil and the expression of high-affinity nitrate uptake systems in those roots. Both these processes are highly regulated to take into account the availability and distribution of external nitrate pools and the endogenous N status of the plant. While significant progress has been made in elucidating the early steps in sensing and responding to external nitrate, there is much less clarity about how the plant monitors its N status. This review specifically addresses the questions of what N compounds are sensed and in which part of the plant, as well as the identity of the signalling pathways responsible for their detection. Candidates that are considered for the role of N sensory systems include the target of rapamycin (TOR) signalling pathway, the general control non-derepressible 2 (GCN2) pathway, the plastidic PII-dependent pathway, and the family of glutamate-like receptors (GLRs). However, despite significant recent progress in elucidating the function and mode of action of these signalling systems, there is still much uncertainty about the extent to which they contribute to the process by which plants monitor their N status. The possibility is discussed that the large GLR family of Ca2+ channels, which are gated by a wide range of different amino acids and expressed throughout the plant, could act as amino acid sensors upstream of a Ca2+-regulated signalling pathway, such as the TOR pathway, to regulate the plant's response to changes in N status.
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Affiliation(s)
- Lucas Gent
- Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK
| | - Brian G Forde
- Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK
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176
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Liu Y, von Wirén N. Ammonium as a signal for physiological and morphological responses in plants. JOURNAL OF EXPERIMENTAL BOTANY 2017; 68:2581-2592. [PMID: 28369490 DOI: 10.1093/jxb/erx086] [Citation(s) in RCA: 177] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Ammonium is a major inorganic nitrogen source for plants. At low external supplies, ammonium promotes plant growth, while at high external supplies it causes toxicity. Ammonium triggers rapid changes in cytosolic pH, in gene expression, and in post-translational modifications of proteins, leading to apoplastic acidification, co-ordinated ammonium uptake, enhanced ammonium assimilation, altered oxidative and phytohormonal status, and reshaped root system architecture. Some of these responses are dependent on AMT-type ammonium transporters and are not linked to a nutritional effect, indicating that ammonium is perceived as a signaling molecule by plant cells. This review summarizes current knowledge of ammonium-triggered physiological and morphological responses and highlights existing and putative mechanisms mediating ammonium signaling and sensing events in plants. We put forward the hypothesis that sensing of ammonium takes place at multiple steps along its transport, storage, and assimilation pathways.
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Affiliation(s)
- Ying Liu
- Molecular Plant Nutrition, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstrasse 3, 06466 Stadt Seeland, OT Gatersleben, Germany
| | - Nicolaus von Wirén
- Molecular Plant Nutrition, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstrasse 3, 06466 Stadt Seeland, OT Gatersleben, Germany
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177
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Sperringer JE, Addington A, Hutson SM. Branched-Chain Amino Acids and Brain Metabolism. Neurochem Res 2017; 42:1697-1709. [DOI: 10.1007/s11064-017-2261-5] [Citation(s) in RCA: 90] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Revised: 04/03/2017] [Accepted: 04/04/2017] [Indexed: 12/11/2022]
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178
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Lahr RM, Fonseca BD, Ciotti GE, Al-Ashtal HA, Jia JJ, Niklaus MR, Blagden SP, Alain T, Berman AJ. La-related protein 1 (LARP1) binds the mRNA cap, blocking eIF4F assembly on TOP mRNAs. eLife 2017. [PMID: 28379136 DOI: 10.7554/elife.24146.] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The 5'terminal oligopyrimidine (5'TOP) motif is a cis-regulatory RNA element located immediately downstream of the 7-methylguanosine [m7G] cap of TOP mRNAs, which encode ribosomal proteins and translation factors. In eukaryotes, this motif coordinates the synchronous and stoichiometric expression of the protein components of the translation machinery. La-related protein 1 (LARP1) binds TOP mRNAs, regulating their stability and translation. We present crystal structures of the human LARP1 DM15 region in complex with a 5'TOP motif, a cap analog (m7GTP), and a capped cytidine (m7GpppC), resolved to 2.6, 1.8 and 1.7 Å, respectively. Our binding, competition, and immunoprecipitation data corroborate and elaborate on the mechanism of 5'TOP motif binding by LARP1. We show that LARP1 directly binds the cap and adjacent 5'TOP motif of TOP mRNAs, effectively impeding access of eIF4E to the cap and preventing eIF4F assembly. Thus, LARP1 is a specialized TOP mRNA cap-binding protein that controls ribosome biogenesis.
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Affiliation(s)
- Roni M Lahr
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, United States
| | - Bruno D Fonseca
- Children's Hospital of Eastern Ontario Research Institute, Ottawa, Canada
| | - Gabrielle E Ciotti
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, United States
| | - Hiba A Al-Ashtal
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, United States
| | - Jian-Jun Jia
- Children's Hospital of Eastern Ontario Research Institute, Ottawa, Canada
| | - Marius R Niklaus
- Children's Hospital of Eastern Ontario Research Institute, Ottawa, Canada
| | - Sarah P Blagden
- Department of Oncology, University of Oxford, Oxford, United Kingdom
| | - Tommy Alain
- Children's Hospital of Eastern Ontario Research Institute, Ottawa, Canada
| | - Andrea J Berman
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, United States
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179
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Lahr RM, Fonseca BD, Ciotti GE, Al-Ashtal HA, Jia JJ, Niklaus MR, Blagden SP, Alain T, Berman AJ. La-related protein 1 (LARP1) binds the mRNA cap, blocking eIF4F assembly on TOP mRNAs. eLife 2017; 6:e24146. [PMID: 28379136 PMCID: PMC5419741 DOI: 10.7554/elife.24146] [Citation(s) in RCA: 112] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2016] [Accepted: 04/04/2017] [Indexed: 01/07/2023] Open
Abstract
The 5'terminal oligopyrimidine (5'TOP) motif is a cis-regulatory RNA element located immediately downstream of the 7-methylguanosine [m7G] cap of TOP mRNAs, which encode ribosomal proteins and translation factors. In eukaryotes, this motif coordinates the synchronous and stoichiometric expression of the protein components of the translation machinery. La-related protein 1 (LARP1) binds TOP mRNAs, regulating their stability and translation. We present crystal structures of the human LARP1 DM15 region in complex with a 5'TOP motif, a cap analog (m7GTP), and a capped cytidine (m7GpppC), resolved to 2.6, 1.8 and 1.7 Å, respectively. Our binding, competition, and immunoprecipitation data corroborate and elaborate on the mechanism of 5'TOP motif binding by LARP1. We show that LARP1 directly binds the cap and adjacent 5'TOP motif of TOP mRNAs, effectively impeding access of eIF4E to the cap and preventing eIF4F assembly. Thus, LARP1 is a specialized TOP mRNA cap-binding protein that controls ribosome biogenesis.
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Affiliation(s)
- Roni M Lahr
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, United States
| | - Bruno D Fonseca
- Children’s Hospital of Eastern Ontario Research Institute, Ottawa, Canada
| | - Gabrielle E Ciotti
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, United States
| | - Hiba A Al-Ashtal
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, United States
| | - Jian-Jun Jia
- Children’s Hospital of Eastern Ontario Research Institute, Ottawa, Canada
| | - Marius R Niklaus
- Children’s Hospital of Eastern Ontario Research Institute, Ottawa, Canada
| | - Sarah P Blagden
- Department of Oncology, University of Oxford, Oxford, United Kingdom
| | - Tommy Alain
- Children’s Hospital of Eastern Ontario Research Institute, Ottawa, Canada
| | - Andrea J Berman
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, United States
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180
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Wei J, Raynor J, Nguyen TLM, Chi H. Nutrient and Metabolic Sensing in T Cell Responses. Front Immunol 2017; 8:247. [PMID: 28337199 PMCID: PMC5343023 DOI: 10.3389/fimmu.2017.00247] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Accepted: 02/20/2017] [Indexed: 12/13/2022] Open
Abstract
T cells play pivotal roles in shaping host immune responses in infectious diseases, autoimmunity, and cancer. The activation of T cells requires immune and growth factor-derived signals. However, alterations in nutrients and metabolic signals tune T cell responses by impinging upon T cell fates and immune functions. In this review, we summarize how key nutrients, including glucose, amino acids, and lipids, and their sensors and transporters shape T cell responses. We also briefly discuss regulation of T cell responses by oxygen and energy sensing mechanisms.
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Affiliation(s)
- Jun Wei
- Department of Immunology, St. Jude Children's Research Hospital , Memphis, TN , USA
| | - Jana Raynor
- Department of Immunology, St. Jude Children's Research Hospital , Memphis, TN , USA
| | - Thanh-Long M Nguyen
- Department of Immunology, St. Jude Children's Research Hospital , Memphis, TN , USA
| | - Hongbo Chi
- Department of Immunology, St. Jude Children's Research Hospital , Memphis, TN , USA
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181
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Abstract
Cancers appear as disordered mixtures of different cells, which is partly why they are hard to treat. We show here that despite this chaos, tumors show local organization that emerges from cellular processes common to most cancers: the altered metabolism of cancer cells and the interactions with stromal cells in the tumor microenvironment. With a multidisciplinary approach combining experiments and computer simulations we revealed that the metabolic activity of cancer cells produces gradients of nutrients and metabolic waste products that act as signals that cells use to know their position with respect to blood vessels. This positional information orchestrates a modular organization of tumor and stromal cells that resembles embryonic organization, which we could exploit as a therapeutic target. The genetic and phenotypic diversity of cells within tumors is a major obstacle for cancer treatment. Because of the stochastic nature of genetic alterations, this intratumoral heterogeneity is often viewed as chaotic. Here we show that the altered metabolism of cancer cells creates predictable gradients of extracellular metabolites that orchestrate the phenotypic diversity of cells in the tumor microenvironment. Combining experiments and mathematical modeling, we show that metabolites consumed and secreted within the tumor microenvironment induce tumor-associated macrophages (TAMs) to differentiate into distinct subpopulations according to local levels of ischemia and their position relative to the vasculature. TAMs integrate levels of hypoxia and lactate into progressive activation of MAPK signaling that induce predictable spatial patterns of gene expression, such as stripes of macrophages expressing arginase 1 (ARG1) and mannose receptor, C type 1 (MRC1). These phenotypic changes are functionally relevant as ischemic macrophages triggered tube-like morphogenesis in neighboring endothelial cells that could restore blood perfusion in nutrient-deprived regions where angiogenic resources are most needed. We propose that gradients of extracellular metabolites act as tumor morphogens that impose order within the microenvironment, much like signaling molecules convey positional information to organize embryonic tissues. Unearthing embryology-like processes in tumors may allow us to control organ-like tumor features such as tissue repair and revascularization and treat intratumoral heterogeneity.
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182
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Abstract
The leap from simple unicellularity to complex multicellularity remains one of life's major enigmas. The origins of metazoan developmental gene regulatory mechanisms are sought by analyzing gene regulation in extant eumetazoans, sponges, and unicellular organisms. The main hypothesis of this manuscript is that, developmental enhancers evolved from unicellular inducible promoters that diversified the expression of regulatory genes during metazoan evolution. Promoters and enhancers are functionally similar; both can regulate the transcription of distal promoters and both direct local transcription. Additionally, enhancers have experimentally characterized structural features that reveal their origin from inducible promoters. The distal co-operative regulation among promoters identified in unicellular opisthokonts possibly represents the precursor of distal regulation of promoters by enhancers. During metazoan evolution, constitutive-type promoters of regulatory genes would have acquired novel receptivity to distal regulatory inputs from promoters of inducible genes that eventually specialized as enhancers. The novel regulatory interactions would have caused constitutively expressed genes controlling differential gene expression in unicellular organisms to become themselves differentially expressed. The consequence of the novel regulatory interactions was that regulatory pathways of unicellular organisms became interlaced and ultimately evolved into the intricate developmental gene regulatory networks (GRNs) of extant metazoans.
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Affiliation(s)
- César Arenas-Mena
- Department of Biology, College of Staten Island and Graduate Center, The City University of New York (CUNY), Staten Island, NY 10314, USA
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183
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Arlia-Ciommo A, Svistkova V, Mohtashami S, Titorenko VI. A novel approach to the discovery of anti-tumor pharmaceuticals: searching for activators of liponecrosis. Oncotarget 2017; 7:5204-25. [PMID: 26636650 PMCID: PMC4868681 DOI: 10.18632/oncotarget.6440] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Accepted: 11/21/2015] [Indexed: 02/04/2023] Open
Abstract
A recently conducted chemical genetic screen for pharmaceuticals that can extend longevity of the yeast Saccharomyces cerevisiae has identified lithocholic acid as a potent anti-aging molecule. It was found that this hydrophobic bile acid is also a selective anti-tumor chemical compound; it kills different types of cultured cancer cells if used at concentrations that do not compromise the viability of non-cancerous cells. These studies have revealed that yeast can be successfully used as a model organism for high-throughput screens aimed at the discovery of selectively acting anti-tumor small molecules. Two metabolic traits of rapidly proliferating fermenting yeast, namely aerobic glycolysis and lipogenesis, are known to be similar to those of cancer cells. The mechanisms underlying these key metabolic features of cancer cells and fermenting yeast have been established; such mechanisms are discussed in this review. We also suggest how a yeast-based chemical genetic screen can be used for the high-throughput development of selective anti-tumor pharmaceuticals that kill only cancer cells. This screen consists of searching for chemical compounds capable of increasing the abundance of membrane lipids enriched in unsaturated fatty acids that would therefore be toxic only to rapidly proliferating cells, such as cancer cells and fermenting yeast.
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Affiliation(s)
| | | | - Sadaf Mohtashami
- Department of Biology, Concordia University, Montreal, Quebec, Canada
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184
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Chen WY, Lin CL, Chuang JH, Chiu FY, Sun YY, Liang MC, Lin Y. Heterogeneous nuclear ribonucleoprotein M associates with mTORC2 and regulates muscle differentiation. Sci Rep 2017; 7:41159. [PMID: 28106162 PMCID: PMC5247691 DOI: 10.1038/srep41159] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2016] [Accepted: 12/14/2016] [Indexed: 12/12/2022] Open
Abstract
Mammalian target of rapamycin (mTOR) plays a range of crucial roles in cell survival, growth, proliferation, metabolism, and morphology. However, mTOR forms two distinct complexes, mTOR complex 1 and mTOR complex 2 (mTORC1 and mTORC2), via association with a series of different components; this allows the complexes to execute their wide range of functions. This study explores further the composition of the mTORC2 complex. Utilizing Rictor knock-out cells, immunoprecipitation and mass spectrometry, a novel Rictor associated protein, heterogeneous nuclear ribonucleoprotein M (hnRNP M), was identified. The association between hnRNP M and Rictor was verified using recombinant and endogenous protein and the binding site was found to be within aa 1~532 of hnRNP M. The presence of hnRNP M significantly affects phosphorylation of SGK1 S422, but not of Akt S473, PKCα S657 and PKCζ T560. Furthermore, hnRNP M also plays a critical role in muscle differentiation because knock-down of either hnRNP M or Rictor in C2C12 myoblasts reduced differentiation. This decrease is able to be rescued by overexpression SGK S422D in hnRNP M knockdown C2C12 myoblasts. Taken together, we have identified a novel Rictor/mTOR binding molecule, hnRNP M, that allows mTORC2 signaling to phosphorylate SGK1 thus regulating muscle differentiation.
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Affiliation(s)
- Wei-Yen Chen
- Department of Life Science, National Taiwan Normal University, Taipei 116, Taiwan
| | - Chia-Lung Lin
- Department of Life Science, National Taiwan Normal University, Taipei 116, Taiwan
| | - Jen-Hua Chuang
- Department of Life Science, National Taiwan Normal University, Taipei 116, Taiwan
| | - Fu-Yu Chiu
- Department of Life Science, National Taiwan Normal University, Taipei 116, Taiwan
| | - Yun-Ya Sun
- Department of Life Science, National Taiwan Normal University, Taipei 116, Taiwan
| | - Mei-Chih Liang
- Department of Biological Science and Technology, National Chiao Tung University, Hsinchu 300, Taiwan
| | - Yenshou Lin
- Department of Life Science, National Taiwan Normal University, Taipei 116, Taiwan
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185
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Kwon O, Kwak D, Ha SH, Jeon H, Park M, Chang Y, Suh PG, Ryu SH. Nudix-type motif 2 contributes to cancer proliferation through the regulation of Rag GTPase-mediated mammalian target of rapamycin complex 1 localization. Cell Signal 2017; 32:24-35. [PMID: 28089905 DOI: 10.1016/j.cellsig.2017.01.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Revised: 12/19/2016] [Accepted: 01/06/2017] [Indexed: 01/14/2023]
Abstract
Lysosomal localization of mammalian target of rapamycin complex 1 (mTORC1) is a critical step for activation of the molecule. Rag GTPases are essential for this translocation. Here, we demonstrate that Nudix-type motif 2 (NUDT2) is a novel positive regulator of mTORC1 activation. Activation of mTORC1 is impaired in NUDT2-silenced cells. Mechanistically, NUDT2 binds to Rag GTPase and controls mTORC1 translocation to the lysosomal membrane. Furthermore, NUDT2-dependent mTORC1 regulation is critical for proliferation of breast cancer cells, as NUDT2-silenced cells arrest in G0/G1 phases. Taken together, these results show that NUDT2 is a novel complex formation enhancing factor regulating mTORC1-Rag GTPase signaling that is crucial for cell growth control.
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Affiliation(s)
- Ohman Kwon
- School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology (POSTECH), Pohang 790-784, Republic of Korea
| | - Dongoh Kwak
- Department of Life Sciences, Pohang University of Science and Technology (POSTECH), Pohang 790-784, Republic of Korea
| | - Sang Hoon Ha
- Department of Life Sciences, Pohang University of Science and Technology (POSTECH), Pohang 790-784, Republic of Korea
| | - Hyeona Jeon
- Department of Life Sciences, Pohang University of Science and Technology (POSTECH), Pohang 790-784, Republic of Korea
| | - Mangeun Park
- School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology (POSTECH), Pohang 790-784, Republic of Korea
| | - Yeonho Chang
- Department of Life Sciences, Pohang University of Science and Technology (POSTECH), Pohang 790-784, Republic of Korea
| | - Pann-Ghill Suh
- School of Nano-Biotechnology and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 689-798, Republic of Korea
| | - Sung Ho Ryu
- School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology (POSTECH), Pohang 790-784, Republic of Korea; Department of Life Sciences, Pohang University of Science and Technology (POSTECH), Pohang 790-784, Republic of Korea.
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186
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Wang B, Li J, Gao J, Cai P, Han X, Tian C. Identification and characterization of the glucose dual-affinity transport system in Neurospora crassa: pleiotropic roles in nutrient transport, signaling, and carbon catabolite repression. BIOTECHNOLOGY FOR BIOFUELS 2017; 10:17. [PMID: 28115989 PMCID: PMC5244594 DOI: 10.1186/s13068-017-0705-4] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Accepted: 01/07/2017] [Indexed: 05/07/2023]
Abstract
BACKGROUND The glucose dual-affinity transport system (low- and high-affinity) is a conserved strategy used by microorganisms to cope with natural fluctuations in nutrient availability in the environment. The glucose-sensing and uptake processes are believed to be tightly associated with cellulase expression regulation in cellulolytic fungi. However, both the identities and functions of the major molecular components of this evolutionarily conserved system in filamentous fungi remain elusive. Here, we systematically identified and characterized the components of the glucose dual-affinity transport system in the model fungus Neurospora crassa. RESULTS Using RNA sequencing coupled with functional transport analyses, we assigned GLT-1 (Km = 18.42 ± 3.38 mM) and HGT-1/-2 (Km = 16.13 ± 0.95 and 98.97 ± 22.02 µM) to the low- and high-affinity glucose transport systems, respectively. The high-affinity transporters hgt-1/-2 complemented a moderate growth defect under high glucose when glt-1 was deleted. Simultaneous deletion of hgt-1/-2 led to extensive derepression of genes for plant cell wall deconstruction in cells grown on cellulose. The suppression by HGT-1/-2 was connected to both carbon catabolite repression (CCR) and the cyclic adenosine monophosphate-protein kinase A pathway. Alteration of a residue conserved across taxa in hexose transporters resulted in a loss of glucose-transporting function, whereas CCR signal transduction was retained, indicating dual functions for HGT-1/-2 as "transceptors." CONCLUSIONS In this study, GLT-1 and HGT-1/-2 were identified as the key components of the glucose dual-affinity transport system, which plays diverse roles in glucose transport and carbon metabolism. Given the wide conservation of the glucose dual-affinity transport system across fungal species, the identification of its components and their pleiotropic roles in this study shed important new light on the molecular basis of nutrient transport, signaling, and plant cell wall degradation in fungi.
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Affiliation(s)
- Bang Wang
- Key Laboratory of Systems Microbial Biotechnology, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308 China
- University of Chinese Academy of Sciences, Beijing, 100049 China
- School of Ophthalmology and Optometry, Eye Hospital, State Key Laboratory Cultivation Base and Key Laboratory of Vision Science, Ministry of Health and Zhejiang Provincial Key Laboratory of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, 325027 China
| | - Jingen Li
- Key Laboratory of Systems Microbial Biotechnology, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308 China
| | - Jingfang Gao
- Key Laboratory of Systems Microbial Biotechnology, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308 China
- School of Life Sciences, Heilongjiang University, Harbin, 150080 Heilongjiang China
| | - Pengli Cai
- Key Laboratory of Systems Microbial Biotechnology, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308 China
| | - Xiaoyun Han
- School of Life Sciences, Heilongjiang University, Harbin, 150080 Heilongjiang China
| | - Chaoguang Tian
- Key Laboratory of Systems Microbial Biotechnology, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308 China
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187
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Alfa RW, Kim SK. Using Drosophila to discover mechanisms underlying type 2 diabetes. Dis Model Mech 2016; 9:365-76. [PMID: 27053133 PMCID: PMC4852505 DOI: 10.1242/dmm.023887] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Mechanisms of glucose homeostasis are remarkably well conserved between the fruit flyDrosophila melanogasterand mammals. From the initial characterization of insulin signaling in the fly came the identification of downstream metabolic pathways for nutrient storage and utilization. Defects in these pathways lead to phenotypes that are analogous to diabetic states in mammals. These discoveries have stimulated interest in leveraging the fly to better understand the genetics of type 2 diabetes mellitus in humans. Type 2 diabetes results from insulin insufficiency in the context of ongoing insulin resistance. Although genetic susceptibility is thought to govern the propensity of individuals to develop type 2 diabetes mellitus under appropriate environmental conditions, many of the human genes associated with the disease in genome-wide association studies have not been functionally studied. Recent advances in the phenotyping of metabolic defects have positionedDrosophilaas an excellent model for the functional characterization of large numbers of genes associated with type 2 diabetes mellitus. Here, we examine results from studies modeling metabolic disease in the fruit fly and compare findings to proposed mechanisms for diabetic phenotypes in mammals. We provide a systematic framework for assessing the contribution of gene candidates to insulin-secretion or insulin-resistance pathways relevant to diabetes pathogenesis.
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Affiliation(s)
- Ronald W Alfa
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305, USA Neuroscience Program, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Seung K Kim
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305, USA Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA 94305, USA Department of Medicine (Oncology), Stanford University School of Medicine, Stanford, CA 94305, USA
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188
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Bouché V, Espinosa AP, Leone L, Sardiello M, Ballabio A, Botas J. Drosophila Mitf regulates the V-ATPase and the lysosomal-autophagic pathway. Autophagy 2016; 12:484-98. [PMID: 26761346 DOI: 10.1080/15548627.2015.1134081] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
An evolutionarily conserved gene network regulates the expression of genes involved in lysosome biogenesis, autophagy, and lipid metabolism. In mammals, TFEB and other members of the MiTF-TFE family of transcription factors control this network. Here we report that the lysosomal-autophagy pathway is controlled by Mitf gene in Drosophila melanogaster. Mitf is the single MiTF-TFE family member in Drosophila and prior to this work was known only for its function in eye development. We show that Mitf regulates the expression of genes encoding V-ATPase subunits as well as many additional genes involved in the lysosomal-autophagy pathway. Reduction of Mitf function leads to abnormal lysosomes and impairs autophagosome fusion and lipid breakdown during the response to starvation. In contrast, elevated Mitf levels increase the number of lysosomes, autophagosomes and autolysosomes, and decrease the size of lipid droplets. Inhibition of Drosophila MTORC1 induces Mitf translocation to the nucleus, underscoring conserved regulatory mechanisms between Drosophila and mammalian systems. Furthermore, we show Mitf-mediated clearance of cytosolic and nuclear expanded ATXN1 (ataxin 1) in a cellular model of spinocerebellar ataxia type 1 (SCA1). This remarkable observation illustrates the potential of the lysosomal-autophagy system to prevent toxic protein aggregation in both the cytoplasmic and nuclear compartments. We anticipate that the genetics of the Drosophila model and the absence of redundant MIT transcription factors will be exploited to investigate the regulation and function of the lysosomal-autophagy gene network.
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Affiliation(s)
- Valentina Bouché
- a Department of Molecular and Human Genetics , Baylor College of Medicine , Houston , TX , USA.,b Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital , Houston , TX , USA.,c Telethon Institute of Genetics and Medicine (TIGEM) , Naples , Italy
| | - Alma Perez Espinosa
- a Department of Molecular and Human Genetics , Baylor College of Medicine , Houston , TX , USA.,b Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital , Houston , TX , USA
| | - Luigi Leone
- a Department of Molecular and Human Genetics , Baylor College of Medicine , Houston , TX , USA.,b Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital , Houston , TX , USA.,d Institute of Biomolecular Chemistry, Consiglio Nazionale delle Ricerche , Pozzuoli , Italy
| | - Marco Sardiello
- a Department of Molecular and Human Genetics , Baylor College of Medicine , Houston , TX , USA.,b Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital , Houston , TX , USA
| | - Andrea Ballabio
- a Department of Molecular and Human Genetics , Baylor College of Medicine , Houston , TX , USA.,b Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital , Houston , TX , USA.,c Telethon Institute of Genetics and Medicine (TIGEM) , Naples , Italy.,e Medical Genetics, Department of Translational Medicine, Federico II University , Naples , Italy
| | - Juan Botas
- a Department of Molecular and Human Genetics , Baylor College of Medicine , Houston , TX , USA.,b Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital , Houston , TX , USA
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189
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A molecular and neuronal basis for amino acid sensing in the Drosophila larva. Sci Rep 2016; 6:34871. [PMID: 27982028 PMCID: PMC5159833 DOI: 10.1038/srep34871] [Citation(s) in RCA: 82] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Accepted: 09/20/2016] [Indexed: 01/06/2023] Open
Abstract
Amino acids are important nutrients for animals, reflected in conserved internal pathways in vertebrates and invertebrates for monitoring cellular levels of these compounds. In mammals, sensory cells and metabotropic glutamate receptor-related taste receptors that detect environmental sources of amino acids in food are also well-characterised. By contrast, it is unclear how insects perceive this class of molecules through peripheral chemosensory mechanisms. Here we investigate amino acid sensing in Drosophila melanogaster larvae, which feed ravenously to support their rapid growth. We show that larvae display diverse behaviours (attraction, aversion, neutral) towards different amino acids, which depend upon stimulus concentration. Some of these behaviours require IR76b, a member of the variant ionotropic glutamate receptor repertoire of invertebrate chemoreceptors. IR76b is broadly expressed in larval taste neurons, suggesting a role as a co-receptor. We identify a subpopulation of these neurons that displays physiological activation by some, but not all, amino acids, and which mediate suppression of feeding by high concentrations of at least a subset of these compounds. Our data reveal the first elements of a sophisticated neuronal and molecular substrate by which these animals detect and behave towards external sources of amino acids.
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190
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McKeown CR, Thompson CK, Cline HT. Reversible developmental stasis in response to nutrient availability in the Xenopus laevis central nervous system. ACTA ACUST UNITED AC 2016; 220:358-368. [PMID: 27875263 DOI: 10.1242/jeb.151043] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Accepted: 11/04/2016] [Indexed: 12/31/2022]
Abstract
Many organisms confront intermittent nutrient restriction (NR), but the mechanisms to cope with nutrient fluctuations during development are not well understood. This is particularly true of the brain, the development and function of which is energy intensive. Here we examine the effects of nutrient availability on visual system development in Xenopus laevis tadpoles. During the first week of development, tadpoles draw nutrients from maternally provided yolk. Upon yolk depletion, animals forage for food. By altering access to external nutrients after yolk depletion, we identified a period of reversible stasis during tadpole development. We demonstrate that NR results in developmental stasis characterized by a decrease in overall growth of the animals, a failure to progress through developmental stages, and a decrease in volume of the optic tectum. During NR, neural progenitors virtually cease proliferation, but tadpoles swim and behave normally. Introducing food after temporary NR increased neural progenitor cell proliferation more than 10-fold relative to NR tadpoles, and cell proliferation was comparable to that of fed counterparts 1 week after delayed feeding. Delayed feeding also rescued NR-induced body length and tectal volume deficits and partially rescued developmental progression defects. Tadpoles recover from developmental stasis if food is provided within the first 9 days of NR, after which access to food fails to increase cell proliferation. These results show that early stages of tadpole brain development are acutely sensitive to fluctuations in nutrient availability and that NR induces developmental stasis from which animals can recover if food becomes available within a critical window.
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Affiliation(s)
- C R McKeown
- Department of Molecular and Cellular Neuroscience, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - C K Thompson
- Department of Molecular and Cellular Neuroscience, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - H T Cline
- Department of Molecular and Cellular Neuroscience, The Scripps Research Institute, La Jolla, CA 92037, USA
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191
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Corrales-Carvajal VM, Faisal AA, Ribeiro C. Internal states drive nutrient homeostasis by modulating exploration-exploitation trade-off. eLife 2016; 5. [PMID: 27770569 PMCID: PMC5108593 DOI: 10.7554/elife.19920] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Accepted: 10/20/2016] [Indexed: 12/16/2022] Open
Abstract
Internal states can profoundly alter the behavior of animals. A quantitative understanding of the behavioral changes upon metabolic challenges is key to a mechanistic dissection of how animals maintain nutritional homeostasis. We used an automated video tracking setup to characterize how amino acid and reproductive states interact to shape exploitation and exploration decisions taken by adult Drosophila melanogaster. We find that these two states have specific effects on the decisions to stop at and leave proteinaceous food patches. Furthermore, the internal nutrient state defines the exploration-exploitation trade-off: nutrient-deprived flies focus on specific patches while satiated flies explore more globally. Finally, we show that olfaction mediates the efficient recognition of yeast as an appropriate protein source in mated females and that octopamine is specifically required to mediate homeostatic postmating responses without affecting internal nutrient sensing. Internal states therefore modulate specific aspects of exploitation and exploration to change nutrient selection. DOI:http://dx.doi.org/10.7554/eLife.19920.001 When making decisions, animals, including humans, do not always choose the same option. One reason for this is that their “internal state” changes the value of different options. This is particularly evident when deciding what type of food to eat. Depending on which nutrients the animal needs, it will choose to eat different foods. Amino acids are key nutrients that affect health, lifespan and reproduction. Female fruit flies that have recently mated, for example, eat more amino acids in order to obtain the raw materials required to produce eggs. Despite the importance of amino acids, little was known about how animal behavior changes in response to a lack of this nutrient. Corrales-Carvajal et al. used a video tracking system to measure the time that fruit flies – some of which had a need for amino acids – spent feeding on patches of yeast (which are rich in amino acids) versus patches of sucrose. Recently mated females – and virgins that had been fed a diet lacking in amino acids – consumed more yeast than sucrose, whereas virgin females that were not amino acid deficient showed the opposite pattern. To bias the fly toward eating the right food for their needs, several aspects of the fly’s behavior changed, including the number and length of individual feeding bouts. These different behaviors did not all change at the same time. The pattern of exploration taken by the flies also depended on their need for amino acids. Amino acid deficient flies spent most of their time near known yeast patches. By contrast, fully fed flies adopted a riskier foraging strategy, moving away from known sources of food to explore their environment more widely. In common with humans, the flies relied upon their sense of smell to efficiently identify different types of food. Overall, the results presented by Corrales-Carvajal et al. provide us with a detailed understanding about how changes to the internal state of the fly affect its behavior. The next step will be to use the powerful genetic tools available for studying fruit flies to reveal the neural circuits and molecular mechanisms that help animals find the types of food that they need. DOI:http://dx.doi.org/10.7554/eLife.19920.002
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Affiliation(s)
- Verónica María Corrales-Carvajal
- Champalimaud Neuroscience Programme, Champalimaud Centre for the Unknown, Lisbon, Portugal.,Department of Bioengineering, Imperial College London, London, United Kingdom
| | - Aldo A Faisal
- Department of Bioengineering, Imperial College London, London, United Kingdom.,Department of Computing, Imperial College London, London, United Kingdom.,Integrative Biology Division, MRC Clinical Sciences Centre, London, United Kingdom
| | - Carlos Ribeiro
- Champalimaud Neuroscience Programme, Champalimaud Centre for the Unknown, Lisbon, Portugal
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192
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Kimura T, Nada S, Takegahara N, Okuno T, Nojima S, Kang S, Ito D, Morimoto K, Hosokawa T, Hayama Y, Mitsui Y, Sakurai N, Sarashina-Kida H, Nishide M, Maeda Y, Takamatsu H, Okuzaki D, Yamada M, Okada M, Kumanogoh A. Polarization of M2 macrophages requires Lamtor1 that integrates cytokine and amino-acid signals. Nat Commun 2016; 7:13130. [PMID: 27731330 PMCID: PMC5064021 DOI: 10.1038/ncomms13130] [Citation(s) in RCA: 100] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Accepted: 09/06/2016] [Indexed: 02/07/2023] Open
Abstract
Macrophages play crucial roles in host defence and tissue homoeostasis, processes in which both environmental stimuli and intracellularly generated metabolites influence activation of macrophages. Activated macrophages are classified into M1 and M2 macrophages. It remains unclear how intracellular nutrition sufficiency, especially for amino acid, influences on macrophage activation. Here we show that a lysosomal adaptor protein Lamtor1, which forms an amino-acid sensing complex with lysosomal vacuolar-type H+-ATPase (v-ATPase), and is the scaffold for amino acid-activated mTORC1 (mechanistic target of rapamycin complex 1), is critically required for M2 polarization. Lamtor1 deficiency, amino-acid starvation, or inhibition of v-ATPase and mTOR result in defective M2 polarization and enhanced M1 polarization. Furthermore, we identified liver X receptor (LXR) as the downstream target of Lamtor1 and mTORC1. Production of 25-hydroxycholesterol is dependent on Lamtor1 and mTORC1. Our findings demonstrate that Lamtor1 plays an essential role in M2 polarization, coupling immunity and metabolism.
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Affiliation(s)
- Tetsuya Kimura
- Department of Immunopathology, World Premier International Immunology Frontier Research Center, Osaka University, Yamadaoka 2-2, Osaka 565-0871 Japan.,Department of Respiratory Medicine, Allergy and Rheumatic Disease, Graduate School of Medicine, Osaka University, Yamadaoka 2-2, Osaka 565-0871, Japan.,The Japan Agency for Medical Research and Development-Core Research for Evolutional Science and Technology (AMED-CREST), Gobancho 7, Tokyo 102-0076, Japan
| | - Shigeyuki Nada
- Department of Oncogene Research, Research Institute for Microbial Diseases, Osaka University, Yamadaoka 3-1, Osaka 565-0871, Japan
| | - Noriko Takegahara
- Department of Immunopathology, World Premier International Immunology Frontier Research Center, Osaka University, Yamadaoka 2-2, Osaka 565-0871 Japan
| | - Tatsusada Okuno
- Department of Immunopathology, World Premier International Immunology Frontier Research Center, Osaka University, Yamadaoka 2-2, Osaka 565-0871 Japan.,Department of Neurology, Graduate School of Medicine, Osaka University, Yamadaoka 2-2, Osaka 565-0871, Japan
| | - Satoshi Nojima
- Department of Immunopathology, World Premier International Immunology Frontier Research Center, Osaka University, Yamadaoka 2-2, Osaka 565-0871 Japan.,The Japan Agency for Medical Research and Development-Core Research for Evolutional Science and Technology (AMED-CREST), Gobancho 7, Tokyo 102-0076, Japan.,Department of Pathology, Graduate School of Medicine, Osaka University, Yamadaoka 2-2, Osaka 565-0871, Japan
| | - Sujin Kang
- Department of Immunopathology, World Premier International Immunology Frontier Research Center, Osaka University, Yamadaoka 2-2, Osaka 565-0871 Japan.,Department of Respiratory Medicine, Allergy and Rheumatic Disease, Graduate School of Medicine, Osaka University, Yamadaoka 2-2, Osaka 565-0871, Japan.,The Japan Agency for Medical Research and Development-Core Research for Evolutional Science and Technology (AMED-CREST), Gobancho 7, Tokyo 102-0076, Japan
| | - Daisuke Ito
- Department of Immunopathology, World Premier International Immunology Frontier Research Center, Osaka University, Yamadaoka 2-2, Osaka 565-0871 Japan.,Department of Respiratory Medicine, Allergy and Rheumatic Disease, Graduate School of Medicine, Osaka University, Yamadaoka 2-2, Osaka 565-0871, Japan.,The Japan Agency for Medical Research and Development-Core Research for Evolutional Science and Technology (AMED-CREST), Gobancho 7, Tokyo 102-0076, Japan
| | - Keiko Morimoto
- Department of Immunopathology, World Premier International Immunology Frontier Research Center, Osaka University, Yamadaoka 2-2, Osaka 565-0871 Japan.,Department of Respiratory Medicine, Allergy and Rheumatic Disease, Graduate School of Medicine, Osaka University, Yamadaoka 2-2, Osaka 565-0871, Japan.,The Japan Agency for Medical Research and Development-Core Research for Evolutional Science and Technology (AMED-CREST), Gobancho 7, Tokyo 102-0076, Japan
| | - Takashi Hosokawa
- Department of Immunopathology, World Premier International Immunology Frontier Research Center, Osaka University, Yamadaoka 2-2, Osaka 565-0871 Japan.,Department of Respiratory Medicine, Allergy and Rheumatic Disease, Graduate School of Medicine, Osaka University, Yamadaoka 2-2, Osaka 565-0871, Japan.,The Japan Agency for Medical Research and Development-Core Research for Evolutional Science and Technology (AMED-CREST), Gobancho 7, Tokyo 102-0076, Japan
| | - Yoshitomo Hayama
- Department of Immunopathology, World Premier International Immunology Frontier Research Center, Osaka University, Yamadaoka 2-2, Osaka 565-0871 Japan.,Department of Respiratory Medicine, Allergy and Rheumatic Disease, Graduate School of Medicine, Osaka University, Yamadaoka 2-2, Osaka 565-0871, Japan.,The Japan Agency for Medical Research and Development-Core Research for Evolutional Science and Technology (AMED-CREST), Gobancho 7, Tokyo 102-0076, Japan
| | - Yuichi Mitsui
- Department of Immunopathology, World Premier International Immunology Frontier Research Center, Osaka University, Yamadaoka 2-2, Osaka 565-0871 Japan.,Department of Respiratory Medicine, Allergy and Rheumatic Disease, Graduate School of Medicine, Osaka University, Yamadaoka 2-2, Osaka 565-0871, Japan
| | - Natsuki Sakurai
- Department of Immunopathology, World Premier International Immunology Frontier Research Center, Osaka University, Yamadaoka 2-2, Osaka 565-0871 Japan
| | - Hana Sarashina-Kida
- Department of Immunopathology, World Premier International Immunology Frontier Research Center, Osaka University, Yamadaoka 2-2, Osaka 565-0871 Japan.,Department of Respiratory Medicine, Allergy and Rheumatic Disease, Graduate School of Medicine, Osaka University, Yamadaoka 2-2, Osaka 565-0871, Japan.,The Japan Agency for Medical Research and Development-Core Research for Evolutional Science and Technology (AMED-CREST), Gobancho 7, Tokyo 102-0076, Japan
| | - Masayuki Nishide
- Department of Immunopathology, World Premier International Immunology Frontier Research Center, Osaka University, Yamadaoka 2-2, Osaka 565-0871 Japan.,Department of Respiratory Medicine, Allergy and Rheumatic Disease, Graduate School of Medicine, Osaka University, Yamadaoka 2-2, Osaka 565-0871, Japan.,The Japan Agency for Medical Research and Development-Core Research for Evolutional Science and Technology (AMED-CREST), Gobancho 7, Tokyo 102-0076, Japan
| | - Yohei Maeda
- Department of Immunopathology, World Premier International Immunology Frontier Research Center, Osaka University, Yamadaoka 2-2, Osaka 565-0871 Japan.,Department of Respiratory Medicine, Allergy and Rheumatic Disease, Graduate School of Medicine, Osaka University, Yamadaoka 2-2, Osaka 565-0871, Japan.,The Japan Agency for Medical Research and Development-Core Research for Evolutional Science and Technology (AMED-CREST), Gobancho 7, Tokyo 102-0076, Japan
| | - Hyota Takamatsu
- Department of Immunopathology, World Premier International Immunology Frontier Research Center, Osaka University, Yamadaoka 2-2, Osaka 565-0871 Japan.,Department of Respiratory Medicine, Allergy and Rheumatic Disease, Graduate School of Medicine, Osaka University, Yamadaoka 2-2, Osaka 565-0871, Japan.,The Japan Agency for Medical Research and Development-Core Research for Evolutional Science and Technology (AMED-CREST), Gobancho 7, Tokyo 102-0076, Japan
| | - Daisuke Okuzaki
- DNA-chip Development Center for Infectious Diseases, Research Institute for Microbial Diseases, Yamadaoka 3-1, Osaka 565-0871, Japan
| | - Masaki Yamada
- Global Application Development Center, Analytical and Measuring Instruments Division, Shimadzu Corporation, Kyoto 604-8511, Japan
| | - Masato Okada
- Department of Oncogene Research, Research Institute for Microbial Diseases, Osaka University, Yamadaoka 3-1, Osaka 565-0871, Japan
| | - Atsushi Kumanogoh
- Department of Immunopathology, World Premier International Immunology Frontier Research Center, Osaka University, Yamadaoka 2-2, Osaka 565-0871 Japan.,Department of Respiratory Medicine, Allergy and Rheumatic Disease, Graduate School of Medicine, Osaka University, Yamadaoka 2-2, Osaka 565-0871, Japan.,The Japan Agency for Medical Research and Development-Core Research for Evolutional Science and Technology (AMED-CREST), Gobancho 7, Tokyo 102-0076, Japan
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193
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Abstract
The lysosome has long been viewed as the recycling center of the cell. However, recent discoveries have challenged this simple view and have established a central role of the lysosome in nutrient-dependent signal transduction. The degradative role of the lysosome and its newly discovered signaling functions are not in conflict but rather cooperate extensively to mediate fundamental cellular activities such as nutrient sensing, metabolic adaptation, and quality control of proteins and organelles. Moreover, lysosome-based signaling and degradation are subject to reciprocal regulation. Transcriptional programs of increasing complexity control the biogenesis, composition, and abundance of lysosomes and fine-tune their activity to match the evolving needs of the cell. Alterations in these essential activities are, not surprisingly, central to the pathophysiology of an ever-expanding spectrum of conditions, including storage disorders, neurodegenerative diseases, and cancer. Thus, unraveling the functions of this fascinating organelle will contribute to our understanding of the fundamental logic of metabolic organization and will point to novel therapeutic avenues in several human diseases.
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Affiliation(s)
- Rushika M Perera
- Department of Anatomy and Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, California 94143;
| | - Roberto Zoncu
- Department of Molecular and Cellular Biology and Paul F. Glenn Center for Aging Research, University of California, Berkeley, California 94720;
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194
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Lim CY, Zoncu R. The lysosome as a command-and-control center for cellular metabolism. J Cell Biol 2016; 214:653-64. [PMID: 27621362 PMCID: PMC5021098 DOI: 10.1083/jcb.201607005] [Citation(s) in RCA: 196] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Accepted: 08/22/2016] [Indexed: 12/25/2022] Open
Abstract
Lysosomes are membrane-bound organelles found in every eukaryotic cell. They are widely known as terminal catabolic stations that rid cells of waste products and scavenge metabolic building blocks that sustain essential biosynthetic reactions during starvation. In recent years, this classical view has been dramatically expanded by the discovery of new roles of the lysosome in nutrient sensing, transcriptional regulation, and metabolic homeostasis. These discoveries have elevated the lysosome to a decision-making center involved in the control of cellular growth and survival. Here we review these recently discovered properties of the lysosome, with a focus on how lysosomal signaling pathways respond to external and internal cues and how they ultimately enable metabolic homeostasis and cellular adaptation.
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Affiliation(s)
- Chun-Yan Lim
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720 The Paul F. Glenn Center for Aging Research at the University of California, Berkeley, Berkeley, CA 94720
| | - Roberto Zoncu
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720 The Paul F. Glenn Center for Aging Research at the University of California, Berkeley, Berkeley, CA 94720
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195
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Restriction of dietary protein decreases mTORC1 in tumors and somatic tissues of a tumor-bearing mouse xenograft model. Oncotarget 2016; 6:31233-40. [PMID: 26378060 PMCID: PMC4741600 DOI: 10.18632/oncotarget.5180] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2015] [Accepted: 08/20/2015] [Indexed: 12/02/2022] Open
Abstract
Reduced dietary protein intake and intermittent fasting (IF) are both linked to healthy longevity in rodents, and are effective in inhibiting cancer growth. The molecular mechanisms underlying the beneficial effects of chronic protein restriction (PR) and IF are unclear, but may be mediated in part by a down-regulation of the IGF/mTOR pathway. In this study we compared the effects of PR and IF on tumor growth in a xenograft mouse model of breast cancer. We also investigated the effects of PR and IF on the mechanistic Target Of Rapamycin (mTOR) pathway, inhibition of which extends lifespan in model organisms including mice. The mTOR protein kinase is found in two distinct complexes, of which mTOR complex 1 (mTORC1) is responsive to acute treatment with amino acids in cell culture and in vivo. We found that both PR and IF inhibit tumor growth and mTORC1 phosphorylation in tumor xenografts. In somatic tissues, we found that PR, but not IF, selectively inhibits the activity of the amino acid sensitive mTORC1, while the activity of the second mTOR complex, mTORC2, was relatively unaffected by PR. In contrast, IF resulted in increased S6 phosphorylation in multiple metabolic tissues. Our work represents the first finding that PR may reduce mTORC1 activity in tumors and multiple somatic tissues, and suggest that PR may represent a highly translatable option for the treatment not only of cancer, but also other age-related diseases.
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196
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Gillespie ZE, Pickering J, Eskiw CH. Better Living through Chemistry: Caloric Restriction (CR) and CR Mimetics Alter Genome Function to Promote Increased Health and Lifespan. Front Genet 2016; 7:142. [PMID: 27588026 PMCID: PMC4988992 DOI: 10.3389/fgene.2016.00142] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Accepted: 07/21/2016] [Indexed: 12/19/2022] Open
Abstract
Caloric restriction (CR), defined as decreased nutrient intake without causing malnutrition, has been documented to increase both health and lifespan across numerous organisms, including humans. Many drugs and other compounds naturally occurring in our diet (nutraceuticals) have been postulated to act as mimetics of caloric restriction, leading to a wave of research investigating the efficacy of these compounds in preventing age-related diseases and promoting healthier, longer lifespans. Although well studied at the biochemical level, there are still many unanswered questions about how CR and CR mimetics impact genome function and structure. Here we discuss how genome function and structure are influenced by CR and potential CR mimetics, including changes in gene expression profiles and epigenetic modifications and their potential to identify the genetic fountain of youth.
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Affiliation(s)
- Zoe E Gillespie
- Department of Food and Bioproduct Sciences, University of Saskatchewan Saskatoon, SK, Canada
| | - Joshua Pickering
- Department of Biochemistry, University of Saskatchewan Saskatoon, SK, Canada
| | - Christopher H Eskiw
- Department of Food and Bioproduct Sciences, University of SaskatchewanSaskatoon, SK, Canada; Department of Biochemistry, University of SaskatchewanSaskatoon, SK, Canada
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197
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Jayakumar S, Richhariya S, Reddy OV, Texada MJ, Hasan G. Drosophila larval to pupal switch under nutrient stress requires IP3R/Ca(2+) signalling in glutamatergic interneurons. eLife 2016; 5:e17495. [PMID: 27494275 PMCID: PMC4993588 DOI: 10.7554/elife.17495] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Accepted: 08/04/2016] [Indexed: 12/19/2022] Open
Abstract
Neuronal circuits are known to integrate nutritional information, but the identity of the circuit components is not completely understood. Amino acids are a class of nutrients that are vital for the growth and function of an organism. Here, we report a neuronal circuit that allows Drosophila larvae to overcome amino acid deprivation and pupariate. We find that nutrient stress is sensed by the class IV multidendritic cholinergic neurons. Through live calcium imaging experiments, we show that these cholinergic stimuli are conveyed to glutamatergic neurons in the ventral ganglion through mAChR. We further show that IP3R-dependent calcium transients in the glutamatergic neurons convey this signal to downstream medial neurosecretory cells (mNSCs). The circuit ultimately converges at the ring gland and regulates expression of ecdysteroid biosynthetic genes. Activity in this circuit is thus likely to be an adaptation that provides a layer of regulation to help surpass nutritional stress during development.
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Affiliation(s)
- Siddharth Jayakumar
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India
- Manipal University, Manipal, India
| | - Shlesha Richhariya
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India
| | - O Venkateswara Reddy
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India
| | - Michael J Texada
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Gaiti Hasan
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India
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198
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Otero-Moreno D, Peña-Rangel MT, Riesgo-Escovar JR. CRECIMIENTO Y METABOLISMO: LA REGULACIÓN Y LA VÍA DE LA INSULINA DESDE LA MOSCA DE LA FRUTA, Drosophila melanogaster. TIP REVISTA ESPECIALIZADA EN CIENCIAS QUÍMICO-BIOLÓGICAS 2016. [DOI: 10.1016/j.recqb.2016.06.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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199
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Zhao J, Goldberg AL. Coordinate regulation of autophagy and the ubiquitin proteasome system by MTOR. Autophagy 2016; 12:1967-1970. [PMID: 27459110 DOI: 10.1080/15548627.2016.1205770] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
Proteins in eukaryotic cells are continually being degraded to amino acids either by the ubiquitin proteasome system (UPS) or by the autophagic-lysosomal pathway. The breakdown of proteins by these 2 degradative pathways involves totally different enzymes that function in distinct subcellular compartments. While most studies of the UPS have focused on the selective ubiquitination and breakdown of specific cell proteins, macroautophagy/autophagy is a more global nonselective process. Consequently, the UPS and autophagy were traditionally assumed to serve distinct physiological functions and to be regulated in quite different manners. However, recent findings indicate that protein breakdown by these 2 systems is coordinately regulated by important physiological stimuli. The activation of MTORC1 by nutrients and hormones rapidly suppresses proteolysis by both proteasomes and autophagy, which helps promote protein accumulation, whereas in nutrient-poor conditions, MTORC1 inactivation causes the simultaneous activation of these 2 degradative pathways to supply the deprived cells with a source of amino acids. Also this selective breakdown of key anabolic proteins by the UPS upon MTORC1 inhibition can help limit growth-related processes (e.g., cholesterol biosynthesis). Thus, the collaboration of these 2 degradative systems, together with the simultaneous control of protein translation by MTORC1, provide clear advantages to the organism in both growth and starvation conditions.
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Affiliation(s)
- Jinghui Zhao
- a Department of Cell Biology , Harvard Medical School , Boston , MA , USA
| | - Alfred L Goldberg
- a Department of Cell Biology , Harvard Medical School , Boston , MA , USA
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200
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Roles of the interorgan neuronal network in the development of metabolic syndrome. Diabetol Int 2016; 7:205-211. [PMID: 30603265 DOI: 10.1007/s13340-016-0277-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 06/26/2016] [Indexed: 01/01/2023]
Abstract
Metabolic processes in different tissues and remote organs are under coordinated systemic regulation, allowing adaptation to a variety of external circumstances. Neuronal signals as well as humoral factors, such as nutrients, growth factors, and hormones, have attracted increasing attention for their roles in this interorgan metabolic network, responsible for the maintenance of metabolic homeostasis at the whole-body level. These interorgan communications within an organism are considered to be diverse and, in fact, we identified previously unknown neuronal relay systems originating in the liver which modulate energy, glucose, and lipid metabolism. Furthermore, when nutrient overload is prolonged, these neuronal mechanisms, which function as an endogenous defense system against obesity development, contribute to the pathophysiological states of metabolic syndrome characterized by obesity-associated features. Therefore, these interorgan neuronal systems are considered to be possible molecular targets for treating metabolic syndrome. We herein review the precise mechanisms underlying the functions of the mammalian interorgan neuronal network, especially the pathways from the liver to several other organs, focusing on their significance and roles in the development of metabolic syndrome.
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