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Athirasala A, Patel S, Menezes PP, Kim J, Tahayeri A, Sahay G, Bertassoni LE. Matrix stiffness regulates lipid nanoparticle-mRNA delivery in cell-laden hydrogels. NANOMEDICINE : NANOTECHNOLOGY, BIOLOGY, AND MEDICINE 2022; 42:102550. [PMID: 35292368 PMCID: PMC9206884 DOI: 10.1016/j.nano.2022.102550] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 01/16/2022] [Accepted: 03/07/2022] [Indexed: 06/03/2023]
Abstract
mRNA therapeutics have increased in popularity, largely due to the transient and fast nature of protein expression and the low risk of off-target effects. This has increased drastically with the remarkable success of mRNA-based vaccines for COVID-19. Despite advances in lipid nanoparticle (LNP)-based delivery, the mechanisms that regulate efficient endocytic trafficking and translation of mRNA remain poorly understood. Although it is widely acknowledged that the extracellular matrix (ECM) regulates uptake and expression of exogenous nano-complexed genetic material, its specific effects on mRNA delivery and expression have not yet been examined. Here, we demonstrate a critical role for matrix stiffness in modulating both mRNA transfection and expression and uncover distinct mechano-regulatory mechanisms for endocytosis of mRNA through RhoA mediated mTOR signaling and cytoskeletal dynamics. Our findings have implications for effective delivery of therapeutic mRNA to targeted tissues that may be differentially affected by tissue and matrix stiffness.
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Affiliation(s)
- Avathamsa Athirasala
- Department of Biomedical Engineering, Collaborative Life Sciences Building, Oregon Health and Science University, Portland, OR, USA
| | - Siddharth Patel
- Department of Pharmaceutical Sciences, College of Pharmacy, Collaborative Life Science Building, Oregon State University, Portland, OR, USA
| | - Paula P Menezes
- Division of Biomaterials and Biomechanics, Department of Restorative Dentistry, School of Dentistry, Oregon Health and Science University, Portland, OR, USA; Department of Pharmacy, Federal University of Sergipe, Aracaju, Sergipe, Brazil
| | - Jeonghwan Kim
- Department of Pharmaceutical Sciences, College of Pharmacy, Collaborative Life Science Building, Oregon State University, Portland, OR, USA
| | - Anthony Tahayeri
- Division of Biomaterials and Biomechanics, Department of Restorative Dentistry, School of Dentistry, Oregon Health and Science University, Portland, OR, USA
| | - Gaurav Sahay
- Department of Biomedical Engineering, Collaborative Life Sciences Building, Oregon Health and Science University, Portland, OR, USA; Department of Pharmaceutical Sciences, College of Pharmacy, Collaborative Life Science Building, Oregon State University, Portland, OR, USA; Department of Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, OR, USA
| | - Luiz E Bertassoni
- Department of Biomedical Engineering, Collaborative Life Sciences Building, Oregon Health and Science University, Portland, OR, USA; Division of Biomaterials and Biomechanics, Department of Restorative Dentistry, School of Dentistry, Oregon Health and Science University, Portland, OR, USA; Center for Regenerative Medicine, Oregon Health and Science University, Portland, OR, USA; Cancer Early Detection Advanced Research (CEDAR) Center, Knight Cancer Institute, Oregon Health and Science University, Portland, OR, USA.
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2
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Jin J, Kim C, Xia Q, Gould TM, Cao W, Zhang H, Li X, Weiskopf D, Grifoni A, Sette A, Weyand CM, Goronzy JJ. Activation of mTORC1 at late endosomes misdirects T cell fate decision in older individuals. Sci Immunol 2021; 6:eabg0791. [PMID: 34145066 PMCID: PMC8422387 DOI: 10.1126/sciimmunol.abg0791] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2020] [Accepted: 05/18/2021] [Indexed: 12/11/2022]
Abstract
The nutrient-sensing mammalian target of rapamycin (mTOR) is integral to cell fate decisions after T cell activation. Sustained mTORC1 activity favors the generation of terminally differentiated effector T cells instead of follicular helper and memory T cells. This is particularly pertinent for T cell responses of older adults who have sustained mTORC1 activation despite dysfunctional lysosomes. Here, we show that lysosome-deficient T cells rely on late endosomes rather than lysosomes as an mTORC1 activation platform, where mTORC1 is activated by sensing cytosolic amino acids. T cells from older adults have an increased expression of the plasma membrane leucine transporter SLC7A5 to provide a cytosolic amino acid source. Hence, SLC7A5 and VPS39 deficiency (a member of the HOPS complex promoting early to late endosome conversion) substantially reduced mTORC1 activities in T cells from older but not young individuals. Late endosomal mTORC1 is independent of the negative-feedback loop involving mTORC1-induced inactivation of the transcription factor TFEB that controls expression of lysosomal genes. The resulting sustained mTORC1 activation impaired lysosome function and prevented lysosomal degradation of PD-1 in CD4+ T cells from older adults, thereby inhibiting their proliferative responses. VPS39 silencing of human T cells improved their expansion to pertussis and to SARS-CoV-2 peptides in vitro. Furthermore, adoptive transfer of CD4+ Vps39-deficient LCMV-specific SMARTA cells improved germinal center responses, CD8+ memory T cell generation, and recall responses to infection. Thus, curtailing late endosomal mTORC1 activity is a promising strategy to enhance T cell immunity.
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Affiliation(s)
- Jun Jin
- Division of Immunology and Rheumatology, Department of Medicine, Stanford University, Stanford, CA, USA
- Department of Medicine, Palo Alto Veterans Administration Healthcare System, Palo Alto, CA, United States
| | - Chulwoo Kim
- Division of Immunology and Rheumatology, Department of Medicine, Stanford University, Stanford, CA, USA
- Department of Medicine, Palo Alto Veterans Administration Healthcare System, Palo Alto, CA, United States
| | - Qiong Xia
- Division of Immunology and Rheumatology, Department of Medicine, Stanford University, Stanford, CA, USA
| | - Timothy M Gould
- Division of Immunology and Rheumatology, Department of Medicine, Stanford University, Stanford, CA, USA
- Department of Medicine, Palo Alto Veterans Administration Healthcare System, Palo Alto, CA, United States
| | - Wenqiang Cao
- Division of Immunology and Rheumatology, Department of Medicine, Stanford University, Stanford, CA, USA
- Department of Medicine, Palo Alto Veterans Administration Healthcare System, Palo Alto, CA, United States
| | - Huimin Zhang
- Division of Immunology and Rheumatology, Department of Medicine, Stanford University, Stanford, CA, USA
- Department of Medicine, Palo Alto Veterans Administration Healthcare System, Palo Alto, CA, United States
| | - Xuanying Li
- Division of Immunology and Rheumatology, Department of Medicine, Stanford University, Stanford, CA, USA
- Department of Medicine, Palo Alto Veterans Administration Healthcare System, Palo Alto, CA, United States
| | - Daniela Weiskopf
- Center for Infectious Disease and Vaccine Research, La Jolla Institute for Immunology, La Jolla, CA, USA
| | - Alba Grifoni
- Center for Infectious Disease and Vaccine Research, La Jolla Institute for Immunology, La Jolla, CA, USA
| | - Alessandro Sette
- Center for Infectious Disease and Vaccine Research, La Jolla Institute for Immunology, La Jolla, CA, USA
- Department of Medicine, Division of Infectious Diseases and Global Public Health, University of California, San Diego, La Jolla, CA, USA
| | - Cornelia M Weyand
- Division of Immunology and Rheumatology, Department of Medicine, Stanford University, Stanford, CA, USA
- Department of Medicine, Palo Alto Veterans Administration Healthcare System, Palo Alto, CA, United States
| | - Jorg J Goronzy
- Division of Immunology and Rheumatology, Department of Medicine, Stanford University, Stanford, CA, USA.
- Department of Medicine, Palo Alto Veterans Administration Healthcare System, Palo Alto, CA, United States
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3
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De D, Mukherjee I, Guha S, Paidi RK, Chakrabarti S, Biswas SC, Bhattacharyya SN. Rheb-mTOR activation rescues Aβ-induced cognitive impairment and memory function by restoring miR-146 activity in glial cells. MOLECULAR THERAPY. NUCLEIC ACIDS 2021; 24:868-887. [PMID: 34094708 PMCID: PMC8141608 DOI: 10.1016/j.omtn.2021.04.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Accepted: 04/09/2021] [Indexed: 12/22/2022]
Abstract
Deposition of amyloid beta plaques in adult rat or human brain is associated with increased production of proinflammatory cytokines by associated glial cells that are responsible for degeneration of the diseased tissue. The expression of these cytokines is usually under check and is controlled at the post-transcriptional level via several microRNAs. Computational analysis of gene expression profiles of cortical regions of Alzheimer’s disease patients’ brain suggests ineffective target cytokine mRNA suppression by existing micro-ribonucleoproteins (miRNPs) in diseased brain. Exploring the mechanism of amyloid beta-induced cytokine expression, we have identified how the inactivation of the repressive miR-146 miRNPs causes increased production of cytokines in amyloid beta-exposed glial cells. In exploration of the cause of miRNP inactivation, we have noted amyloid beta oligomer-induced sequestration of the mTORC1 complex to early endosomes that results in decreased Ago2 phosphorylation, limited Ago2-miRNA uncoupling, and retarded Ago2-cytokine mRNA interaction in rat astrocytes. Interestingly, constitutive activation of mTORC1 by Rheb activator restricts proinflammatory cytokine production by reactivating miR-146 miRNPs in amyloid beta-exposed glial cells to rescue the disease phenotype in the in vivo rat model of Alzheimer’s disease.
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Affiliation(s)
- Dipayan De
- RNA Biology Research Laboratory, Molecular Genetics Division, CSIR-Indian Institute of Chemical Biology, Kolkata 700032, India
| | - Ishita Mukherjee
- Structural Biology and Bio-informatics Division, CSIR-Indian Institute of Chemical Biology, Kolkata 700032, India
| | - Subhalakshmi Guha
- Cell Biology and Physiology Division, CSIR-Indian Institute of Chemical Biology, Kolkata 700032, India
| | - Ramesh Kumar Paidi
- Cell Biology and Physiology Division, CSIR-Indian Institute of Chemical Biology, Kolkata 700032, India
| | - Saikat Chakrabarti
- Structural Biology and Bio-informatics Division, CSIR-Indian Institute of Chemical Biology, Kolkata 700032, India
| | - Subhas C Biswas
- Cell Biology and Physiology Division, CSIR-Indian Institute of Chemical Biology, Kolkata 700032, India
| | - Suvendra N Bhattacharyya
- RNA Biology Research Laboratory, Molecular Genetics Division, CSIR-Indian Institute of Chemical Biology, Kolkata 700032, India
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4
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Moore MN, Sforzini S, Viarengo A, Barranger A, Aminot Y, Readman JW, Khlobystov AN, Arlt VM, Banni M, Jha AN. Antagonistic cytoprotective effects of C 60 fullerene nanoparticles in simultaneous exposure to benzo[a]pyrene in a molluscan animal model. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 755:142355. [PMID: 33022458 DOI: 10.1016/j.scitotenv.2020.142355] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 09/10/2020] [Accepted: 09/11/2020] [Indexed: 06/11/2023]
Abstract
The hypothesis that C60 fullerene nanoparticles (C60) exert an antagonistic interactive effect on the toxicity of benzo[a]pyrene (BaP) has been supported by this investigation. Mussels were exposed to BaP (5, 50 & 100μg/L) and C60 (C60-1mg/L) separately and in combination. Both BaP and C60 were shown to co-localize in the secondary lysosomes of the hepatopancreatic digestive cells in the digestive gland where they reduced lysosomal membrane stability (LMS) or increased membrane permeability, while BaP also induced increased lysosomal lipid and lipofuscin, indicative of oxidative cell injury and autophagic dysfunction. Combinations of BaP and C60 showed antagonistic effects for lysosomal stability, mTORC1 (mechanistic target of rapamycin complex 1) inhibition and intralysosomal lipid (5 & 50μg/L BaP). The biomarker data (i.e., LMS, lysosomal lipidosis and lipofuscin accumulation; lysosomal/cell volume and dephosphorylation of mTORC1) were further analysed using multivariate statistics. Principal component and cluster analysis clearly indicated that BaP on its own was more injurious than in combination with C60. Use of a network model that integrated the biomarker data for the cell pathophysiological processes, indicated that there were significant antagonistic interactions in network complexity (% connectance) at all BaP concentrations for the combined treatments. Loss of lysosomal membrane stability probably causes the release of intralysosomal iron and hydrolases into the cytosol, where iron can generate harmful reactive oxygen species (ROS). It was inferred that this adverse oxidative reaction induced by BaP was ameliorated in the combination treatments by the ROS scavenging property of intralysosomal C60, thus limiting the injury to the lysosomal membrane; and reducing the oxidative damage in the cytosol and to the nuclear DNA. The ROS scavenging by C60, in combination with enhanced autophagic turnover of damaged cell constituents, appeared to have a cytoprotective effect against the toxic reaction to BaP in the combined treatments.
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Affiliation(s)
- Michael N Moore
- School of Biological and Marine Sciences, University of Plymouth, Plymouth PL4 8AA, UK; European Centre for Environment & Human Health (ECEHH), University of Exeter Medical School, Knowledge Spa, Royal Cornwall Hospital, Cornwall TR1 3LJ, UK; Plymouth Marine Laboratory, Prospect Place, The Hoe, Plymouth PL1 3HD, UK.
| | - Susanna Sforzini
- Institute for the Study of Anthropic Impacts and Sustainability in Marine Environment - IAS, National Research Council - CNR, Via de Marini, 6, 16149 Genova, GE, Italy
| | - Aldo Viarengo
- Institute for the Study of Anthropic Impacts and Sustainability in Marine Environment - IAS, National Research Council - CNR, Via de Marini, 6, 16149 Genova, GE, Italy
| | - Audrey Barranger
- School of Biological and Marine Sciences, University of Plymouth, Plymouth PL4 8AA, UK
| | - Yann Aminot
- School of Biological and Marine Sciences, University of Plymouth, Plymouth PL4 8AA, UK
| | - James W Readman
- School of Biological and Marine Sciences, University of Plymouth, Plymouth PL4 8AA, UK; Plymouth Marine Laboratory, Prospect Place, The Hoe, Plymouth PL1 3HD, UK
| | - Andrei N Khlobystov
- School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, UK; Nanoscale and Microscale Research Centre, University of Nottingham, University Park, Nottingham NG7 2RD, UK
| | - Volker M Arlt
- Department of Analytical, Environmental and Forensic Sciences, King's College London, MRC-PHE Centre for Environmental & Health, London SE1 9NH, UK; Toxicology Department, GAB Consulting GmbH, 69126 Heidelberg, Germany
| | - Mohamed Banni
- Laboratory of Biochemistry and Environmental Toxicology, ISA, Chott-Mariem, Sousse, Tunisia
| | - Awadhesh N Jha
- School of Biological and Marine Sciences, University of Plymouth, Plymouth PL4 8AA, UK
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5
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Sforzini S, Oliveri C, Barranger A, Jha AN, Banni M, Moore MN, Viarengo A. Effects of fullerene C 60 in blue mussels: Role of mTOR in autophagy related cellular/tissue alterations. CHEMOSPHERE 2020; 246:125707. [PMID: 31891845 DOI: 10.1016/j.chemosphere.2019.125707] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 12/10/2019] [Accepted: 12/18/2019] [Indexed: 06/10/2023]
Abstract
The effects of C60 on mTOR (mechanistic Target of Rapamycin) activity in mussel digestive gland were investigated. mTOR is a kinase that senses physiological and environmental signals to control eukaryotic cell growth. mTOR is present in two complexes: the phosphorylated mTORC1 regulates cell growth by activating anabolic processes, and by inhibiting catabolic processes (i.e. autophagy); mTORC2 also modulates actin cytoskeleton organization. Mussels were exposed to C60 (0.01, 0.1 and 1 mg/L) for 72 h. Immunocytochemical analysis using a specific antibody revealed the cellular distribution of C60 in mussel digestive gland, already at the lowest concentration. In exposed mussels, the dephosphorylation of mTORC1 and mTORC2 may explain the C60 effects, i.e. the reduction of lysosomal membrane stability, the enhancement of LC3B protein, and the increase of lysosomal/cytoplasmic volume ratio; as well the cytoskeletal alterations. No oxidative stress was observed. Multivariate analysis was used to facilitate the interpretation of the biomarker data. Finally, a low density oligo-microarray was used to understand the cellular responses to fullerene. Transcriptomics identified a number of differentially expressed genes (DEGs) showing a maximum in animals exposed to 0.1 mg/L C60. The most affected processes are associated with energy metabolism, lysosomal activity and cytoskeleton organization. In this study, we report the first data on the subcellular distribution of C60 in mussel's cells; and on the involvement of mTOR inhibition in the alterations due to nanoparticle accumulation. Overall, mTOR deregulation, by affecting protein synthesis, energy metabolism and autophagy, may reduce the capacity of the organisms to effectively grow and reproduce.
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Affiliation(s)
- Susanna Sforzini
- Department of Sciences and Technological Innovation (DiSIT), University of Piemonte Orientale "A. Avogadro", V.le T. Michel 11, 15121, Alessandria, Italy
| | - Caterina Oliveri
- Department of Sciences and Technological Innovation (DiSIT), University of Piemonte Orientale "A. Avogadro", V.le T. Michel 11, 15121, Alessandria, Italy
| | - Audrey Barranger
- School of Biological and Marine Sciences, University of Plymouth, Drake Circus, Plymouth, PL4 8AA, UK
| | - Awadhesh N Jha
- School of Biological and Marine Sciences, University of Plymouth, Drake Circus, Plymouth, PL4 8AA, UK
| | - Mohamed Banni
- Laboratory of Biochemistry and Environmental Toxicology, ISA, Chott-Mariem, Sousse, Tunisia
| | - Michael N Moore
- School of Biological and Marine Sciences, University of Plymouth, Drake Circus, Plymouth, PL4 8AA, UK; European Centre for Environment & Human Health (ECEHH), University of Exeter Medical School, Truro, TR1 3HD, UK; Plymouth Marine Laboratory, Plymouth, PL1 3DH, UK
| | - Aldo Viarengo
- Institute for the study of Anthropic impacts and Sustainability in marine environment, National research Council (CNR-IAS), Via de Marini 6, 16149, Genova, Italy.
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Moore MN, Shaw JP, Pascoe C, Beesley A, Viarengo A, Lowe DM. Anti-oxidative hormetic effects of cellular autophagy induced by nutrient deprivation in a molluscan animal model. MARINE ENVIRONMENTAL RESEARCH 2020; 156:104903. [PMID: 32056801 DOI: 10.1016/j.marenvres.2020.104903] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 01/24/2020] [Accepted: 02/03/2020] [Indexed: 06/10/2023]
Abstract
This investigation using a molluscan animal model tested the hypothesis that experimentally induced lysosomal autophagy protects against oxidative cell injury. Induction of augmented lysosomal autophagy has previously been implicated in this protective process. Four treatment groups of blue mussels (Mytilus galloprovincialis) were used: Group 1 (fed - control), Group 2 (fasted), Group 3 (copper + fed) and Group 4 (copper + fasted). Groups 2 and 4 were fasted in order to trigger autophagy; and samples of hepatopancreas (liver analogue or digestive gland) from all 4 groups were taken at 3, 6 and 15 days. Treatment with copper provided a positive reference for oxidative stress: Groups 3 and 4 were treated with copper (10 μg Cu2+/animal/day) for three days only. Oxidative damage and cellular injury in hepatopancreatic digestive cells was found to decrease in Group 2 (fasted) compared to Group 1 (fed - control). Group 3 (fed + copper) showed clear evidence of oxidative stress and cell injury, as well as induction of antioxidant activities. Group 4 (copper + fasted) had a reduced uptake of copper and toxicity of copper was also reduced, compared with Group 3. It was concluded that augmented autophagy had a hormetic cytoprotective anti-oxidant effect.
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Affiliation(s)
- M N Moore
- Plymouth Marine Laboratory, Prospect Place, The Hoe, Plymouth, Devon, PL1 3DH, UK; European Centre for Environment & Human Health (ECEHH), University of Exeter Medical School, Knowledge Spa, Royal Cornwall Hospital, Truro, TR1 3HD, UK; School of Biological & Marine Sciences, University of Plymouth, Drake Circus, Plymouth, PL4 8AA, UK.
| | - J P Shaw
- Plymouth Marine Laboratory, Prospect Place, The Hoe, Plymouth, Devon, PL1 3DH, UK
| | - C Pascoe
- Plymouth Marine Laboratory, Prospect Place, The Hoe, Plymouth, Devon, PL1 3DH, UK
| | - A Beesley
- Plymouth Marine Laboratory, Prospect Place, The Hoe, Plymouth, Devon, PL1 3DH, UK
| | - A Viarengo
- Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Via La Masa 19-20156, Milano, Italy
| | - D M Lowe
- Plymouth Marine Laboratory, Prospect Place, The Hoe, Plymouth, Devon, PL1 3DH, UK
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Shaw JP, Moore MN, Readman JW, Mou Z, Langston WJ, Lowe DM, Frickers PE, Al-Moosawi L, Pascoe C, Beesley A. Oxidative stress, lysosomal damage and dysfunctional autophagy in molluscan hepatopancreas (digestive gland) induced by chemical contaminants. MARINE ENVIRONMENTAL RESEARCH 2019; 152:104825. [PMID: 31668363 DOI: 10.1016/j.marenvres.2019.104825] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Revised: 10/10/2019] [Accepted: 10/13/2019] [Indexed: 06/10/2023]
Abstract
Autophagy is a highly conserved evolutionary survival or defence process that enables cells and organisms to survive periods of environmental stress by breaking down cellular organelles and macromolecules in autolysosomes to provide a supply of nutrients for cell maintenance. However, autophagy is also a part of normal cellular physiology that facilitates the turnover of cellular constituents under normal conditions: it can be readily augmented by mild environmental stress; but becomes dysfunctional with severe oxidative stress leading to cellular pathology. The molluscan hepatopancreas or digestive gland provides a versatile and environmentally relevant model to investigate lysosomal autophagy and stress-induced dysfunctional autophagy. This latter process has been implicated in many animal and human disease conditions, including degenerative and neurodegenerative diseases, as well as obesity related conditions. Many environmental pollutants have also been found to induce dysfunctional autophagy in molluscan hepatopancreatic digestive cells, and in this study, the marine blue mussel Mytilus galloprovincialis was exposed for 7 days to: 0.1 μM, 1 μM and 10 μM concentrations of fluoranthene and phenanthrene (PAHs); chlorpyrifos and malathion (organophosphorus compounds); atrazine (triazine herbicide); copper (transition metal) and dodecylbenzene sulphonic acid (LAS, surfactant). The marine snail or periwinkle, Littorina littorea, was also exposed to phenanthrene, chlorpyrifos and copper. Indices of oxidative stress, cell injury and dysfunctional autophagy were measured (i.e., lysosomal membrane stability, protein carbonyls, lipofuscin, and lysosomal accumulation of lipid or lipidosis). Evidence of oxidative stress, based on the elevation of lipofuscin and protein carbonyls, was found for all compounds tested; with chlorpyrifos being the most toxic to both species. Dysfunctional autophagy was induced by all of the compounds tested in both species, except for atrazine in mussels. This failure of normal autophagy was consistently associated with oxidative stress. Autophagic dysfunction is an important emerging feature in the aetiology of many disease conditions in animals and humans; and an explanatory conceptual mechanistic model has been developed for dysregulation of autophagy in response to oxidative stress.
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Affiliation(s)
- J P Shaw
- Plymouth Marine Laboratory, Prospect Place, the Hoe, Plymouth, Devon, PL1 3DH, UK
| | - M N Moore
- Plymouth Marine Laboratory, Prospect Place, the Hoe, Plymouth, Devon, PL1 3DH, UK; European Centre for Environment & Human Health (ECEHH), University of Exeter Medical School, Knowledge Spa, Royal Cornwall Hospital, Truro, TR1 3HD, UK; School of Biological & Marine Sciences, University of Plymouth, Drake Circus, Plymouth, PL4 8AA, UK.
| | - J W Readman
- Plymouth Marine Laboratory, Prospect Place, the Hoe, Plymouth, Devon, PL1 3DH, UK; School of Biological & Marine Sciences, University of Plymouth, Drake Circus, Plymouth, PL4 8AA, UK
| | - Z Mou
- Plymouth Marine Laboratory, Prospect Place, the Hoe, Plymouth, Devon, PL1 3DH, UK
| | - W J Langston
- Marine Biological Association UK, Citadel Hill, Plymouth, Devon, PL1 2PB, UK
| | - D M Lowe
- Plymouth Marine Laboratory, Prospect Place, the Hoe, Plymouth, Devon, PL1 3DH, UK
| | - P E Frickers
- Plymouth Marine Laboratory, Prospect Place, the Hoe, Plymouth, Devon, PL1 3DH, UK
| | - L Al-Moosawi
- Plymouth Marine Laboratory, Prospect Place, the Hoe, Plymouth, Devon, PL1 3DH, UK
| | - C Pascoe
- Plymouth Marine Laboratory, Prospect Place, the Hoe, Plymouth, Devon, PL1 3DH, UK
| | - A Beesley
- Plymouth Marine Laboratory, Prospect Place, the Hoe, Plymouth, Devon, PL1 3DH, UK
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8
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Rentero C, Blanco-Muñoz P, Meneses-Salas E, Grewal T, Enrich C. Annexins-Coordinators of Cholesterol Homeostasis in Endocytic Pathways. Int J Mol Sci 2018; 19:E1444. [PMID: 29757220 PMCID: PMC5983649 DOI: 10.3390/ijms19051444] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Revised: 05/09/2018] [Accepted: 05/10/2018] [Indexed: 02/07/2023] Open
Abstract
The spatiotemporal regulation of calcium (Ca2+) storage in late endosomes (LE) and lysosomes (Lys) is increasingly recognized to influence a variety of membrane trafficking events, including endocytosis, exocytosis, and autophagy. Alterations in Ca2+ homeostasis within the LE/Lys compartment are implicated in human diseases, ranging from lysosomal storage diseases (LSDs) to neurodegeneration and cancer, and they correlate with changes in the membrane binding behaviour of Ca2+-binding proteins. This also includes Annexins (AnxA), which is a family of Ca2+-binding proteins participating in membrane traffic and tethering, microdomain organization, cytoskeleton interactions, Ca2+ signalling, and LE/Lys positioning. Although our knowledge regarding the way Annexins contribute to LE/Lys functions is still incomplete, recruitment of Annexins to LE/Lys is greatly influenced by the availability of Annexin bindings sites, including acidic phospholipids, such as phosphatidylserine (PS) and phosphatidic acid (PA), cholesterol, and phosphatidylinositol (4,5)-bisphosphate (PIP2). Moreover, the cytosolic portion of LE/Lys membrane proteins may also, directly or indirectly, determine the recruitment of Annexins to LE. Strikingly, within LE/Lys, AnxA1, A2, A6, and A8 differentially contribute to cholesterol transport along the endocytic route, in particular, cholesterol transfer between LE and other compartments, positioning Annexins at the centre of major pathways mediating cellular cholesterol homeostasis. Underlying mechanisms include the formation of membrane contact sites (MCS) and intraluminal vesicles (ILV), as well as the modulation of LE-cholesterol transporter activity. In this review, we will summarize the current understanding how Annexins contribute to influence LE/Lys membrane transport and associated functions.
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Affiliation(s)
- Carles Rentero
- Departament de Biomedicina, Unitat de Biologia Cel·lular, Facultat de Medicina i Ciències de la Salut, Universitat de Barcelona. 08036 Barcelona. Spain.
| | - Patricia Blanco-Muñoz
- Departament de Biomedicina, Unitat de Biologia Cel·lular, Facultat de Medicina i Ciències de la Salut, Universitat de Barcelona. 08036 Barcelona. Spain.
| | - Elsa Meneses-Salas
- Departament de Biomedicina, Unitat de Biologia Cel·lular, Facultat de Medicina i Ciències de la Salut, Universitat de Barcelona. 08036 Barcelona. Spain.
| | - Thomas Grewal
- School of Pharmacy, Faculty of Medicine and Health, University of Sydney, Sydney, NSW 2006, Australia.
| | - Carlos Enrich
- Departament de Biomedicina, Unitat de Biologia Cel·lular, Facultat de Medicina i Ciències de la Salut, Universitat de Barcelona. 08036 Barcelona. Spain.
- Centre de Recerca Biomèdica CELLEX, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), 08036 Barcelona, Spain.
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9
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Sforzini S, Moore MN, Oliveri C, Volta A, Jha A, Banni M, Viarengo A. Role of mTOR in autophagic and lysosomal reactions to environmental stressors in molluscs. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2018; 195:114-128. [PMID: 29306034 DOI: 10.1016/j.aquatox.2017.12.014] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 12/15/2017] [Accepted: 12/27/2017] [Indexed: 06/07/2023]
Abstract
Lysosomal membrane stability (LMS) has been used in various organisms as a very sensitive biomarker of stress. However, despite the abundance of data about regulation of the autophagic process in mammals, in the invertebrates there is only limited mechanistic understanding. Marine mussels (Mytilus galloprovincialis Lam.) are bivalve molluscs, widely used as models in ecotoxicology and as environmental bioindicators of sea water quality. In order to elucidate this fundamental process, in the present study, mussels were exposed for 3 days to a "priority", ubiquitous environmental contaminant, benzo[a]pyrene (B[a]P) at different concentrations (i.e. 5, 50, 100 μg/L seawater). B[a]P accumulated in lysosomes of digestive tubule epithelial cells (digestive cells) and in enlarged lipid-rich lysosomes (autolysosomes) as detected by immunofluorescence and UV-fluorescence. B[a]P also activated the autophagic process with a marked decrease of LMS and concurrent increase in lysosomal/cytoplasmic volume ratio. Dephosphorylation of mTOR contributes to increased lysosomal membrane permeability and induced autophagy. B[a]P induced a decrease in phosphorylated (active form) mTOR. The probable role of mTOR in cell signalling and the regulation of the cellular responses to the contaminants has been also confirmed in a field study, where there was significant inactivation of mTOR in stressed animals. Statistical and network modelling supported the empirical investigations of autophagy and mTOR; and was used to integrate the mechanistic biomarker data with chemical analysis and DNA damage.
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Affiliation(s)
- Susanna Sforzini
- Department of Sciences and Technological Innovation (DiSIT), University of Piemonte Orientale "A. Avogadro", V.le T. Michel 11, 15121 Alessandria, Italy; Laboratory of Environmental Chemistry and Toxicology, IRCCS, Istituto di Ricerche Farmacologiche Mario Negri, Via Giuseppe La Masa 19, 20156 Milan, Italy
| | - Michael N Moore
- Department of Sciences and Technological Innovation (DiSIT), University of Piemonte Orientale "A. Avogadro", V.le T. Michel 11, 15121 Alessandria, Italy; European Centre for Environment & Human Health (ECEHH), University of Exeter Medical School, Truro, TR1 3HD, UK; Plymouth Marine Laboratory, Plymouth, PL1 3DH, UK; School of Biological and Marine Sciences, University of Plymouth, Drake Circus, Plymouth, PL4 8AA, UK
| | - Caterina Oliveri
- Department of Sciences and Technological Innovation (DiSIT), University of Piemonte Orientale "A. Avogadro", V.le T. Michel 11, 15121 Alessandria, Italy
| | - Anna Volta
- Department of Sciences and Technological Innovation (DiSIT), University of Piemonte Orientale "A. Avogadro", V.le T. Michel 11, 15121 Alessandria, Italy
| | - Awadhesh Jha
- School of Biological and Marine Sciences, University of Plymouth, Drake Circus, Plymouth, PL4 8AA, UK
| | - Mohamed Banni
- Department of Sciences and Technological Innovation (DiSIT), University of Piemonte Orientale "A. Avogadro", V.le T. Michel 11, 15121 Alessandria, Italy; Laboratory of Biochemistry and Environmental Toxicology, ISA, Chott-Mariem, Sousse, Tunisia
| | - Aldo Viarengo
- Department of Sciences and Technological Innovation (DiSIT), University of Piemonte Orientale "A. Avogadro", V.le T. Michel 11, 15121 Alessandria, Italy; Laboratory of Environmental Chemistry and Toxicology, IRCCS, Istituto di Ricerche Farmacologiche Mario Negri, Via Giuseppe La Masa 19, 20156 Milan, Italy.
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10
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Evolving View of Membrane Trafficking and Signaling Systems for G Protein-Coupled Receptors. ENDOCYTOSIS AND SIGNALING 2018; 57:273-299. [DOI: 10.1007/978-3-319-96704-2_10] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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11
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Ejzykowicz DE, Locken KM, Ruiz FJ, Manandhar SP, Olson DK, Gharakhanian E. Hygromycin B hypersensitive (hhy) mutants implicate an intact trans-Golgi and late endosome interface in efficient Tor1 vacuolar localization and TORC1 function. Curr Genet 2016; 63:531-551. [PMID: 27812735 DOI: 10.1007/s00294-016-0660-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Revised: 10/20/2016] [Accepted: 10/22/2016] [Indexed: 12/18/2022]
Abstract
Saccharomyces cerevisiae vacuoles are functionally analogous to mammalian lysosomes. Both also serve as physical platforms for Tor Complex 1 (TORC1) signal transduction, the master regulator of cellular growth and proliferation. Hygromycin B is a eukaryotic translation inhibitor. We recently reported on hygromycin B hypersensitive (hhy) mutants that fail to grow at subtranslation inhibitory concentrations of the drug and exhibit vacuolar defects (Banuelos et al. in Curr Genet 56:121-137, 2010). Here, we show that hhy phenotype is not due to increased sensitivity to translation inhibition and establish a super HHY (s-HHY) subgroup of genes comprised of ARF1, CHC1, DRS2, SAC1, VPS1, VPS34, VPS45, VPS52, and VPS54 that function exclusively or inclusively at trans-Golgi and late endosome interface. Live cell imaging of s-hhy mutants revealed that hygromycin B treatment disrupts vacuolar morphology and the localization of late endosome marker Pep12, but not that of late endosome-independent vacuolar SNARE Vam3. This, along with normal post-late endosome trafficking of the vital dye FM4-64, establishes that severe hypersensitivity to hygromycin B correlates specifically with compromised trans-Golgi and late endosome interface. We also show that Tor1p vacuolar localization and TORC1 anabolic functions, including growth promotion and phosphorylation of its direct substrate Sch9, are compromised in s-hhy mutants. Thus, an intact trans-Golgi and late endosome interface is a requisite for efficient Tor1 vacuolar localization and TORC1 function.
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Affiliation(s)
- Daniele E Ejzykowicz
- Department of Biological Sciences, California State University Long Beach, 1250 Bellflower Blvd, Long Beach, CA, 90840, USA
| | - Kristopher M Locken
- Department of Biological Sciences, California State University Long Beach, 1250 Bellflower Blvd, Long Beach, CA, 90840, USA
| | - Fiona J Ruiz
- Department of Biological Sciences, California State University Long Beach, 1250 Bellflower Blvd, Long Beach, CA, 90840, USA.,Department of Radiation Oncology, Cancer Biology Division, Washington University School of Medicine, Saint Louis, MO, 63108, USA
| | - Surya P Manandhar
- Department of Biological Sciences, California State University Long Beach, 1250 Bellflower Blvd, Long Beach, CA, 90840, USA
| | - Daniel K Olson
- Department of Biological Sciences, California State University Long Beach, 1250 Bellflower Blvd, Long Beach, CA, 90840, USA.,Inouye Center for Microbial Oceanography, Research and Education, University of Hawaii, Manoa, Honolulu, HI, 96822, USA
| | - Editte Gharakhanian
- Department of Biological Sciences, California State University Long Beach, 1250 Bellflower Blvd, Long Beach, CA, 90840, USA.
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12
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Vesicular Trafficking Systems Impact TORC1-Controlled Transcriptional Programs in Saccharomyces cerevisiae. G3-GENES GENOMES GENETICS 2016; 6:641-52. [PMID: 26739646 PMCID: PMC4777127 DOI: 10.1534/g3.115.023911] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The Target of Rapamycin Complex I (TORC1) orchestrates global reprogramming of transcriptional programs in response to myriad environmental conditions, yet, despite the commonality of the TORC1 complex components, different TORC1-inhibitory conditions do not elicit a uniform transcriptional response. In Saccharomyces cerevisiae, TORC1 regulates the expression of nitrogen catabolite repressed (NCR) genes by controlling the nuclear translocation of the NCR transactivator Gln3. Moreover, Golgi-to-endosome trafficking was shown to be required for nuclear translocation of Gln3 upon a shift from rich medium to the poor nitrogen source proline, but not upon rapamycin treatment. Here, we employed microarray profiling to survey the full impact of the vesicular trafficking system on yeast TORC1-orchestrated transcriptional programs. In addition to the NCR genes, we found that ribosomal protein, ribosome biogenesis, phosphate-responsive, and sulfur-containing amino acid metabolism genes are perturbed by disruption of Golgi-to-endosome trafficking following a nutritional shift from rich to poor nitrogen source medium, but not upon rapamycin treatment. Similar to Gln3, defects in Golgi-to-endosome trafficking significantly delayed cytoplasmic–nuclear translocation of Sfp1, but did not detectably affect the cytoplasmic–nuclear or nuclear–cytoplasmic translocation of Met4, which are the transactivators of these genes. Thus, Golgi-to-endosome trafficking defects perturb TORC1 transcriptional programs via multiple mechanisms. Our findings further delineate the downstream transcriptional responses of TORC1 inhibition by rapamycin compared with a nitrogen quality downshift. Given the conservation of both TORC1 and endomembrane networks throughout eukaryotes, our findings may also have implications for TORC1-mediated responses to nutritional cues in mammals and other eukaryotes.
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13
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Tessneer KL, Jackson RM, Griesel BA, Olson AL. Rab5 activity regulates GLUT4 sorting into insulin-responsive and non-insulin-responsive endosomal compartments: a potential mechanism for development of insulin resistance. Endocrinology 2014; 155:3315-28. [PMID: 24932807 PMCID: PMC4138579 DOI: 10.1210/en.2013-2148] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Glucose transporter isoform 4 (GLUT4) is the insulin-responsive glucose transporter mediating glucose uptake in adipose and skeletal muscle. Reduced GLUT4 translocation from intracellular storage compartments to the plasma membrane is a cause of peripheral insulin resistance. Using a chronic hyperinsulinemia (CHI)-induced cell model of insulin resistance and Rab5 mutant overexpression, we determined these manipulations altered endosomal sorting of GLUT4, thus contributing to the development of insulin resistance. We found that CHI induced insulin resistance in 3T3-L1 adipocytes by retaining GLUT4 in a Rab5-activity-dependent compartment that is unable to equilibrate with the cell surface in response to insulin. Furthermore, CHI-mediated retention of GLUT4 in this non-insulin-responsive compartment impaired filling of the transferrin receptor (TfR)-positive and TfR-negative insulin-responsive storage compartments. Our data suggest that hyperinsulinemia may inhibit GLUT4 by chronically maintaining GLUT4 in the Rab5 activity-dependent endosomal pathway and impairing formation of the TfR-negative and TfR-positive insulin-responsive GLUT4 pools. This model suggests that an early event in the development of insulin-resistant glucose transport in adipose tissue is to alter the intracellular localization of GLUT4 to a compartment that does not efficiently equilibrate with the cell surface when insulin levels are elevated for prolonged periods of time.
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Affiliation(s)
- Kandice L Tessneer
- Department of Biochemistry and Molecular Biology (K.L.T., R.M.J., B.A.G., A.L.O.), University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73126; and Cardiovascular Biology Program (K.L.T.), Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma 73104
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14
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Endolysosomal membrane trafficking complexes drive nutrient-dependent TORC1 signaling to control cell growth in Saccharomyces cerevisiae. Genetics 2014; 196:1077-89. [PMID: 24514902 DOI: 10.1534/genetics.114.161646] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The rapamycin-sensitive and endomembrane-associated TORC1 pathway controls cell growth in response to nutrients in eukaryotes. Mutations in class C Vps (Vps-C) complexes are synthetically lethal with tor1 mutations and confer rapamycin hypersensitivity in Saccharomyces cerevisiae, suggesting a role for these complexes in TORC1 signaling. Vps-C complexes are required for vesicular trafficking and fusion and comprise four distinct complexes: HOPS and CORVET and their minor intermediaries (i)-CORVET and i-HOPS. We show that at least one Vps-C complex is required to promote TORC1 activity, with the HOPS complex having the greatest input. The vps-c mutants fail to recover from rapamycin-induced growth arrest and show low levels of TORC1 activity. TORC1 promotes cell growth via Sch9, a p70(S6) kinase ortholog. Constitutively active SCH9 or hyperactive TOR1 alleles restored rapamycin recovery and TORC1 activity of vps-c mutants, supporting a role for the Vps-C complexes upstream of TORC1. The EGO GTPase complex Exit from G0 Complex (EGOC) and its homologous Rag-GTPase complex convey amino acid signals to TORC1 in yeast and mammals, respectively. Expression of the activated EGOC GTPase subunits Gtr1(GTP) and Gtr2(GDP) partially suppressed vps-c mutant rapamycin recovery defects, and this suppression was enhanced by increased amino acid concentrations. Moreover, vps-c mutations disrupted EGOC-TORC1 interactions. TORC1 defects were more severe for vps-c mutants than those observed in EGOC mutants. Taken together, our results support a model in which distinct endolysosomal trafficking Vps-C complexes promote rapamycin-sensitive TORC1 activity via multiple inputs, one of which involves maintenance of amino acid homeostasis that is sensed and transmitted to TORC1 via interactions with EGOC.
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15
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Swinnen E, Ghillebert R, Wilms T, Winderickx J. Molecular mechanisms linking the evolutionary conserved TORC1-Sch9 nutrient signalling branch to lifespan regulation in Saccharomyces cerevisiae. FEMS Yeast Res 2013; 14:17-32. [PMID: 24102693 DOI: 10.1111/1567-1364.12097] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2013] [Revised: 07/09/2013] [Accepted: 09/06/2013] [Indexed: 01/13/2023] Open
Abstract
The knowledge on the molecular aspects regulating ageing in eukaryotic organisms has benefitted greatly from studies using the budding yeast Saccharomyces cerevisiae. Indeed, many aspects involved in the control of lifespan appear to be well conserved among species. Of these, the lifespan-extending effects of calorie restriction (CR) and downregulation of nutrient signalling through the target of rapamycin (TOR) pathway are prime examples. Here, we present an overview on the molecular mechanisms by which these interventions mediate lifespan extension in yeast. Several models have been proposed in the literature, which should be seen as complementary, instead of contradictory. Results indicate that CR mediates a large amount of its effect by downregulating signalling through the TORC1-Sch9 branch. In addition, we note that Sch9 is more than solely a downstream effector of TORC1, and documented connections with sphingolipid metabolism may be particularly interesting for future research on ageing mechanisms. As Sch9 comprises the yeast orthologue of the mammalian PKB/Akt and S6K1 kinases, future studies in yeast may continue to serve as an attractive model to elucidate conserved mechanisms involved in ageing and age-related diseases in humans.
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16
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Panchaud N, Péli-Gulli MP, De Virgilio C. SEACing the GAP that nEGOCiates TORC1 activation: evolutionary conservation of Rag GTPase regulation. Cell Cycle 2013; 12:2948-52. [PMID: 23974112 PMCID: PMC3875668 DOI: 10.4161/cc.26000] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The target of rapamycin complex 1 (TORC1) regulates eukaryotic cell growth in response to a variety of input signals. In S. cerevisiae, amino acids activate TORC1 through the Rag guanosine triphosphatase (GTPase) heterodimer composed of Gtr1 and Gtr2 found together with Ego1 and Ego3 in the EGO complex (EGOC). The GTPase activity of Gtr1 is regulated by the SEA complex (SEAC). Specifically, SEACIT, a SEAC subcomplex containing Iml1, Npr2, and Npr3 functions as a GTPase activator (GAP) for Gtr1 to decrease the activity of TORC1 and, consequently, growth, after amino acid deprivation. Here, we present genetic epistasis data, which show that SEACAT, the other SEAC subcomplex, containing Seh1, Sea2–4, and Sec13, antagonizes the GAP function of SEACIT. Orthologs of EGOC (Ragulator), SEACIT (GATOR1), and SEACAT (GATOR2) are present in higher eukaryotes, highlighting the remarkable conservation, from yeast to man, of Rag GTPase and TORC1 regulation.
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Affiliation(s)
- Nicolas Panchaud
- Department of Biology; Division of Biochemistry; University of Fribourg; Fribourg, Switzerland
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17
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Yang H, Gong R, Xu Y. Control of cell growth: Rag GTPases in activation of TORC1. Cell Mol Life Sci 2013; 70:2873-85. [PMID: 23242467 PMCID: PMC11113833 DOI: 10.1007/s00018-012-1195-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2012] [Revised: 10/01/2012] [Accepted: 10/11/2012] [Indexed: 01/30/2023]
Abstract
The target of rapamycin (TOR) is a central regulator controlling cell growth. TOR is highly conserved from yeast to mammals, and is deregulated in human cancers and diabetes. TOR complex 1 (TORC1) integrates signals from growth factors, cellular energy status, stress, and amino acids to control cell growth, mitochondrial metabolism, and lipid biosynthesis. The mechanisms of growth factors and cellular energy status in regulating TORC1 have been well established, whereas the mechanism by which amino acid induces TORC1 remains largely unknown. Recent studies revealed that Rag GTPases play a central role in the regulation of TORC1 activation in response to amino acids. In this review, we will discuss the recent progress in our understanding of Rag GTPase-regulated TORC1 activation in response to amino acids. Particular focus will be given to the function of Rag GTPases in TORC1 activation and how Rag GTPases are regulated by amino acids.
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Affiliation(s)
- Huirong Yang
- Cancer Institute, Shanghai Cancer Center, Fudan University, Shanghai, 200032 People’s Republic of China
- Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, 200032 People’s Republic of China
- Institute of Biomedical Sciences, Fudan University, 130 Dong-An Road, Shanghai, 200032 People’s Republic of China
| | - Rui Gong
- Cancer Institute, Shanghai Cancer Center, Fudan University, Shanghai, 200032 People’s Republic of China
- Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, 200032 People’s Republic of China
- Institute of Biomedical Sciences, Fudan University, 130 Dong-An Road, Shanghai, 200032 People’s Republic of China
| | - Yanhui Xu
- Cancer Institute, Shanghai Cancer Center, Fudan University, Shanghai, 200032 People’s Republic of China
- Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, 200032 People’s Republic of China
- Institute of Biomedical Sciences, Fudan University, 130 Dong-An Road, Shanghai, 200032 People’s Republic of China
- State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai, 200433 People’s Republic of China
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18
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Verweij FJ, Middeldorp JM, Pegtel DM. Intracellular signaling controlled by the endosomal-exosomal pathway. Commun Integr Biol 2012; 5:88-93. [PMID: 22482020 DOI: 10.4161/cib.18452] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Tight control of intracellular signaling is essential for developmental processes such as cell differentiation, migration but also for maintaining tissue homeostasis. Disruption in the control of these signaling pathways can result in cell death (apoptosis), anergy or uncontrolled cell proliferation and growth leading to cancer. In multicellular organisms, timely termination of signaling is thus equally important as initiation. Known pathways for downregulating membrane receptor-mediated signaling are mediated via specialized endosomal organelles known as lysosomes and proteosomes that degrade such proteins in the cytoplasm. An alternative pathway for attenuating receptor-mediated signaling was recently discovered independently by the group of M. Caplan and our own group.1,2 It appears that apart from the classical protein degradation machineries, the release of signaling proteins also effectively restricts signaling of at least two major signal transduction routes; the canonical Wnt/β-catenin and NFκB pathways. Expelling proteins from the cell, rather than coordinated degradation in lysosomes may involve defined protein modifications, such as ubiquitination, myristyolation, and/or palmitoylation, but little experimental data are currently available. Although the secretion of proteins via exosomes starts by accumulation within multivesicular bodies (MVBs), a key distinction with degredatory MVBs is that exosome-producing MVBs seem to preferentially fuse with the plasmamembrane (Fig. 1). Here we discuss the latest developments in the biology of exosomes and their unexpected effect on intracellular signal transduction.
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Affiliation(s)
- Frederik J Verweij
- Department of Pathology; Cancer Center Amsterdam; VU University Medical Center; Amsterdam, The Netherlands
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19
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Babu M, Vlasblom J, Pu S, Guo X, Graham C, Bean BDM, Burston HE, Vizeacoumar FJ, Snider J, Phanse S, Fong V, Tam YYC, Davey M, Hnatshak O, Bajaj N, Chandran S, Punna T, Christopolous C, Wong V, Yu A, Zhong G, Li J, Stagljar I, Conibear E, Wodak SJ, Emili A, Greenblatt JF. Interaction landscape of membrane-protein complexes in Saccharomyces cerevisiae. Nature 2012; 489:585-9. [PMID: 22940862 DOI: 10.1038/nature11354] [Citation(s) in RCA: 176] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2011] [Accepted: 06/27/2012] [Indexed: 01/03/2023]
Abstract
Macromolecular assemblies involving membrane proteins (MPs) serve vital biological roles and are prime drug targets in a variety of diseases. Large-scale affinity purification studies of soluble-protein complexes have been accomplished for diverse model organisms, but no global characterization of MP-complex membership has been described so far. Here we report a complete survey of 1,590 putative integral, peripheral and lipid-anchored MPs from Saccharomyces cerevisiae, which were affinity purified in the presence of non-denaturing detergents. The identities of the co-purifying proteins were determined by tandem mass spectrometry and subsequently used to derive a high-confidence physical interaction map encompassing 1,726 membrane protein-protein interactions and 501 putative heteromeric complexes associated with the various cellular membrane systems. Our analysis reveals unexpected physical associations underlying the membrane biology of eukaryotes and delineates the global topological landscape of the membrane interactome.
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Affiliation(s)
- Mohan Babu
- Banting and Best Department of Medical Research, Donnelly Centre, 160 College Street, University of Toronto, Toronto, Ontario M5S 3E1, Canada
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20
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A genome-wide immunodetection screen in S. cerevisiae uncovers novel genes involved in lysosomal vacuole function and morphology. PLoS One 2011; 6:e23696. [PMID: 21912603 PMCID: PMC3166051 DOI: 10.1371/journal.pone.0023696] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Accepted: 07/22/2011] [Indexed: 11/19/2022] Open
Abstract
Vacuoles of yeast Saccharomyces cerevisiae are functionally analogous to mammalian lysosomes. Both are cellular organelles responsible for macromolecular degradation, ion/pH homeostasis, and stress survival. We hypothesized that undefined gene functions remain at post-endosomal stage of vacuolar events and performed a genome-wide screen directed at such functions at the late endosome and vacuole interface – ENV genes. The immunodetection screen was designed to identify mutants that internally accumulate precursor form of the vacuolar hydrolase carboxypeptidase Y (CPY). Here, we report the uncovering and initial characterizations of twelve ENV genes. The small size of the collection and the lack of genes previously identified with vacuolar events are suggestive of the intended exclusive functional interface of the screen. Most notably, the collection includes four novel genes ENV7, ENV9, ENV10, and ENV11, and three genes previously linked to mitochondrial processes – MAM3, PCP1, PPE1. In all env mutants, vesicular trafficking stages were undisturbed in live cells as assessed by invertase and active α-factor secretion, as well as by localization of the endocytic fluorescent marker FM4-64 to the vacuole. Several mutants exhibit defects in stress survival functions associated with vacuoles. Confocal fluorescence microscopy revealed the collection to be significantly enriched in vacuolar morphologies suggestive of fusion and fission defects. These include the unique phenotype of lumenal vesicles within vacuoles in the novel env9Δ mutant and severely fragmented vacuoles upon deletion of GET4, a gene recently implicated in tail anchored membrane protein insertion. Thus, our results establish new gene functions in vacuolar function and morphology, and suggest a link between vacuolar and mitochondrial events.
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21
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Zoncu R, Efeyan A, Sabatini DM. mTOR: from growth signal integration to cancer, diabetes and ageing. Nat Rev Mol Cell Biol 2010; 12:21-35. [PMID: 21157483 DOI: 10.1038/nrm3025] [Citation(s) in RCA: 3033] [Impact Index Per Article: 216.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
In all eukaryotes, the target of rapamycin (TOR) signalling pathway couples energy and nutrient abundance to the execution of cell growth and division, owing to the ability of TOR protein kinase to simultaneously sense energy, nutrients and stress and, in metazoans, growth factors. Mammalian TOR complex 1 (mTORC1) and mTORC2 exert their actions by regulating other important kinases, such as S6 kinase (S6K) and Akt. In the past few years, a significant advance in our understanding of the regulation and functions of mTOR has revealed the crucial involvement of this signalling pathway in the onset and progression of diabetes, cancer and ageing.
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Affiliation(s)
- Roberto Zoncu
- Whitehead Institute for Biomedical Research, Nine Cambridge Center, Cambridge, Massachusetts 02142, USA
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22
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Mitra S, Cheng KW, Mills GB. Rab GTPases implicated in inherited and acquired disorders. Semin Cell Dev Biol 2010; 22:57-68. [PMID: 21147240 DOI: 10.1016/j.semcdb.2010.12.005] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2010] [Revised: 12/06/2010] [Accepted: 12/06/2010] [Indexed: 01/05/2023]
Abstract
The endocytotic machinery imports, transports and exports receptors and associated molecules between the plasma membrane and various cytoplasmic chambers resulting in selective recycling, degradation, or secretion of molecules and signaling complexes. Trafficking of receptors, growth factors, nutrients, cytokines, integrins as well as pathogens dictates the kinetics and magnitude of signal transduction cascades. Understandably, alterations in the 'fate' of such cargo complexes have profound physiologic and pathophysiologic implications. Rab GTPases regulate endocytosis by decorating intracellular vesicles and targeting these vesicles along with their cargoes to appropriate subcellular compartments. In the last decade, the number of genetic diseases driven by germline mutations in Rab GTPases or their interacting proteins, has increased and there is growing evidence of aberrant Rab GTPase function in acquired pathophysiologies such as immune deficiency, infection, obesity, diabetes and cancer.
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Affiliation(s)
- Shreya Mitra
- Department of Systems Biology, The University of Texas, MD Anderson Cancer Center, Houston, TX 77054-1942, USA.
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