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Santos-Araujo S, Bomfim L, Araripe LO, Bruno R, Ramos I, Gondim KC. Silencing of ATG6 and ATG8 promotes increased levels of triacylglycerol (TAG) in the fat body during prolonged starvation periods in the Chagas disease vector Rhodnius prolixus. Insect Biochem Mol Biol 2020; 127:103484. [PMID: 33022370 DOI: 10.1016/j.ibmb.2020.103484] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Revised: 09/18/2020] [Accepted: 09/29/2020] [Indexed: 06/11/2023]
Abstract
Rhodnius prolixus is an obligatorily hematophagous insect known as an important vector of Chagas disease. Autophagy is a conserved cellular mechanism that acts in response to nutrient starvation, where components of the cytoplasm are sequestered by a double membrane organelle, named autophagosome, which is targeted to fuse with the lysosome for degradation. Lipophagy is the process of lipid degradation by selective autophagy, where autophagosomes sequester lipid droplets and degrade triacylglycerol (TAG) generating free fatty acids for β-oxidation. Here, two essential genes of the autophagic pathway, Atg6/Beclin1 (RpAtg6) and Atg8/LC3 (RpAtg8), were silenced and the storage of lipids during starvation in Rhodnius prolixus was monitored. We found that RNAi knockdown of both RpAtg6 and RpAtg8 resulted in higher levels of TAG in the fat body and the flight muscle, 24 days after the blood meal, as well as a larger average diameter of the lipid droplets in the fat body, as seen by Nile Red staining under the confocal fluorescence microscope. Silenced starved insects had lower survival rates when compared to control insects. Accordingly, when examined during the starvation period for monitored activity, silenced insects had lower spontaneous locomotor activity and lower forced flight rates. Furthermore, we found that some genes involved in lipid metabolism had their expression levels altered in silenced insects, such as the Brummer lipase (down regulated) and the adipokinetic hormone receptor (up regulated), suggesting that, as previously observed in mammalian models, the autophagy and neutral lipolysis machineries are interconnected at the transcriptional level. Altogether, our data indicate that autophagy in the fat body is important to allow insects to mobilize energy from lipid stores.
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Affiliation(s)
- Samara Santos-Araujo
- Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Brazil
| | - Larissa Bomfim
- Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Brazil
| | - Luciana O Araripe
- Laboratório de Biologia Molecular de Insetos, Instituto Oswaldo Cruz. Rio de Janeiro, Brazil; Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular - INCT-EM/CNPq, Brazil
| | - Rafaela Bruno
- Laboratório de Biologia Molecular de Insetos, Instituto Oswaldo Cruz. Rio de Janeiro, Brazil; Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular - INCT-EM/CNPq, Brazil
| | - Isabela Ramos
- Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Brazil; Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular - INCT-EM/CNPq, Brazil
| | - Katia C Gondim
- Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Brazil; Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular - INCT-EM/CNPq, Brazil.
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Chang JT, Kumsta C, Hellman AB, Adams LM, Hansen M. Spatiotemporal regulation of autophagy during Caenorhabditis elegans aging. eLife 2017; 6. [PMID: 28675140 PMCID: PMC5496740 DOI: 10.7554/elife.18459] [Citation(s) in RCA: 141] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2016] [Accepted: 06/04/2017] [Indexed: 12/20/2022] Open
Abstract
Autophagy has been linked to longevity in many species, but the underlying mechanisms are unclear. Using a GFP-tagged and a new tandem-tagged Atg8/LGG-1 reporter, we quantified autophagic vesicles and performed autophagic flux assays in multiple tissues of wild-type Caenorhabditis elegans and long-lived daf-2/insulin/IGF-1 and glp-1/Notch mutants throughout adulthood. Our data are consistent with an age-related decline in autophagic activity in the intestine, body-wall muscle, pharynx, and neurons of wild-type animals. In contrast, daf-2 and glp-1 mutants displayed unique age- and tissue-specific changes in autophagic activity, indicating that the two longevity paradigms have distinct effects on autophagy during aging. Although autophagy appeared active in the intestine of both long-lived mutants, inhibition of intestinal autophagy significantly abrogated lifespan extension only in glp-1 mutants. Collectively, our data suggest that autophagic activity normally decreases with age in C. elegans, whereas daf-2 and glp-1 long-lived mutants regulate autophagy in distinct spatiotemporal-specific manners to extend lifespan. DOI:http://dx.doi.org/10.7554/eLife.18459.001
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Affiliation(s)
- Jessica T Chang
- Program of Development, Aging and Regeneration, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, United States
| | - Caroline Kumsta
- Program of Development, Aging and Regeneration, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, United States
| | - Andrew B Hellman
- Program of Development, Aging and Regeneration, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, United States
| | - Linnea M Adams
- Program of Development, Aging and Regeneration, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, United States
| | - Malene Hansen
- Program of Development, Aging and Regeneration, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, United States
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3
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Loi M, Gannagé M, Münz C. ATGs help MHC class II, but inhibit MHC class I antigen presentation. Autophagy 2016; 12:1681-2. [PMID: 27439741 PMCID: PMC5082774 DOI: 10.1080/15548627.2016.1203488] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Revised: 06/08/2016] [Accepted: 06/13/2016] [Indexed: 10/21/2022] Open
Abstract
We have recently shown that the LC3/Atg8 lipidation machinery of macroautophagy is involved in the internalization of MHC class I molecules. Decreased internalization in the absence of ATG5 or ATG7 leads to MHC class I surface stabilization on dendritic cells and macrophages, resulting in elevated CD8(+) T cell responses during viral infections and improved immune control. Here, we discuss how the autophagic machinery supports MHC class II restricted antigen presentation, while compromising MHC class I presentation via internalization and degradation.
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Affiliation(s)
- Monica Loi
- Viral Immunobiology, Institute of Experimental Immunology, University of Zurich, Zurich, Switzerland
| | - Monique Gannagé
- Department of Pathology and Immunology, School of Medicine, University of Geneva, Geneva, Switzerland
| | - Christian Münz
- Viral Immunobiology, Institute of Experimental Immunology, University of Zurich, Zurich, Switzerland
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Goode A, Butler K, Long J, Cavey J, Scott D, Shaw B, Sollenberger J, Gell C, Johansen T, Oldham NJ, Searle MS, Layfield R. Defective recognition of LC3B by mutant SQSTM1/p62 implicates impairment of autophagy as a pathogenic mechanism in ALS-FTLD. Autophagy 2016; 12:1094-104. [PMID: 27158844 PMCID: PMC4990988 DOI: 10.1080/15548627.2016.1170257] [Citation(s) in RCA: 109] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Growing evidence implicates impairment of autophagy as a candidate pathogenic mechanism in the spectrum of neurodegenerative disorders which includes amyotrophic lateral sclerosis and frontotemporal lobar degeneration (ALS-FTLD). SQSTM1, which encodes the autophagy receptor SQSTM1/p62, is genetically associated with ALS-FTLD, although to date autophagy-relevant functional defects in disease-associated variants have not been described. A key protein-protein interaction in autophagy is the recognition of a lipid-anchored form of LC3 (LC3-II) within the phagophore membrane by SQSTM1, mediated through its LC3-interacting region (LIR), and notably some ALS-FTLD mutations map to this region. Here we show that although representing a conservative substitution and predicted to be benign, the ALS-associated L341V mutation of SQSTM1 is defective in recognition of LC3B. We place our observations on a firm quantitative footing by showing the L341V-mutant LIR is associated with a ∼3-fold reduction in LC3B binding affinity and using protein NMR we rationalize the structural basis for the effect. This functional deficit is realized in motor neuron-like cells, with the L341V mutant EGFP-mCherry-SQSTM1 less readily incorporated into acidic autophagic vesicles than the wild type. Our data supports a model in which the L341V mutation limits the critical step of SQSTM1 recruitment to the phagophore. The oligomeric nature of SQSTM1, which presents multiple LIRs to template growth of the phagophore, potentially gives rise to avidity effects which amplify the relatively modest impact of any single mutation on LC3B binding. Over the lifetime of a neuron, impaired autophagy could expose a vulnerability, which ultimately tips the balance from cell survival toward cell death.
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Affiliation(s)
- Alice Goode
- a School of Life Sciences, University of Nottingham , Nottingham , UK
| | - Kevin Butler
- b School of Chemistry, University of Nottingham , Nottingham , UK.,c Centre for Biomolecular Sciences, University of Nottingham , Nottingham , UK
| | - Jed Long
- b School of Chemistry, University of Nottingham , Nottingham , UK.,c Centre for Biomolecular Sciences, University of Nottingham , Nottingham , UK
| | - James Cavey
- a School of Life Sciences, University of Nottingham , Nottingham , UK
| | - Daniel Scott
- a School of Life Sciences, University of Nottingham , Nottingham , UK
| | - Barry Shaw
- a School of Life Sciences, University of Nottingham , Nottingham , UK
| | - Jill Sollenberger
- b School of Chemistry, University of Nottingham , Nottingham , UK.,c Centre for Biomolecular Sciences, University of Nottingham , Nottingham , UK
| | - Christopher Gell
- a School of Life Sciences, University of Nottingham , Nottingham , UK
| | - Terje Johansen
- d Molecular Cancer Research Group, Institute of Medical Biology, University of Tromsø - The Arctic University of Norway , Tromsø , Norway
| | - Neil J Oldham
- b School of Chemistry, University of Nottingham , Nottingham , UK
| | - Mark S Searle
- b School of Chemistry, University of Nottingham , Nottingham , UK.,c Centre for Biomolecular Sciences, University of Nottingham , Nottingham , UK
| | - Robert Layfield
- a School of Life Sciences, University of Nottingham , Nottingham , UK
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Abstract
We have recently shown that the Epstein Barr virus (EBV) incorporates the autophagic membrane label LC3B-II into mature virus particles. Upon EBV production, autophagic membranes are stabilized and infectious viral particle production is dependent on these, because ATG protein-deficiency dampens, whereas rapamycin induces, infectious particle production. Moreover, viral DNA accumulates in the cytosol when macroautophagy is impaired. We therefore conclude that EBV needs autophagic membranes for efficient enveloping during infectious viral particle production. Here, we discuss how EBV might incorporate lipidated LC3B (LC3B-II) into the viral envelope and how other viruses as well as cellular processes customize the macroautophagy machinery for exocytosis in the context of unconventional secretion.
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Affiliation(s)
- Heike Nowag
- a Viral Immunobiology ; Institute of Experimental Immunology ; University of Zurich ; Zurich , Switzerland
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Nowag H, Guhl B, Thriene K, Romao S, Ziegler U, Dengjel J, Münz C. Macroautophagy Proteins Assist Epstein Barr Virus Production and Get Incorporated Into the Virus Particles. EBioMedicine 2014; 1:116-25. [PMID: 26137519 PMCID: PMC4457436 DOI: 10.1016/j.ebiom.2014.11.007] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Revised: 11/04/2014] [Accepted: 11/06/2014] [Indexed: 01/16/2023] Open
Abstract
Epstein Barr virus (EBV) persists as a latent herpes virus infection in the majority of the adult human population. The virus can reactivate from this latent infection into lytic replication for virus particle production. Here, we report that autophagic membranes, which engulf cytoplasmic constituents during macroautophagy and transport them to lysosomal degradation, are stabilized by lytic EBV replication in infected epithelial and B cells. Inhibition of autophagic membrane formation compromises infectious particle production and leads to the accumulation of viral DNA in the cytosol. Vice versa, pharmacological stimulation of autophagic membrane formation enhances infectious virus production. Atg8/LC3, an essential macroautophagy protein and substrate anchor on autophagic membranes, was found in virus preparations, suggesting that EBV recruits Atg8/LC3 coupled membranes to its envelope in the cytosol. Our data indicate that EBV subverts macroautophagy and uses autophagic membranes for efficient envelope acquisition during lytic infection. Macroautophagic membranes are stabilized during lytic EBV replication. Inhibition of macroautophagic membrane formation reduces EBV production. Stimulation of macroautophagic membrane formation boosts EBV production. Without macroautophagic membranes EBV DNA accumulates in the cytosol. Macroautophagic membranes get incorporated into EBV particles.
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Key Words
- Atg, autophagy related gene
- Atg12
- Atg16
- Atg8/LC3
- B cell
- BALF1, BamH1 A fragment leftward reading frame 1
- BALF4, BamH1 A fragment leftward reading frame 4
- BHRF1, BamH1 H fragment rightward reading frame 1
- BMRF1, BamH1 M fragment rightward reading frame 1
- BNRF1, BamH1 N fragment rightward reading frame 1
- BRLF1, BamH1 R fragment leftward reading frame 1
- BZLF1
- BZLF1, BamH1 Z fragment leftward reading frame 1
- EBNA1, Epstein Barr virus nuclear antigen 1
- EBV, Epstein Barr virus
- Epithelial cell
- LMP1, latent membrane protein 1
- Lytic EBV replication
- vFLIP, viral FLICE-like inhibitor protein
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Affiliation(s)
- Heike Nowag
- Viral Immunobiology, Institute of Experimental Immunology, University of Zürich, 8057 Zürich, Switzerland
| | - Bruno Guhl
- Center for Microscopy and Image Analysis, University of Zürich, 8057 Zürich, Switzerland
| | - Kerstin Thriene
- Department of Dermatology, Medical Center, University of Freiburg, Hauptstr. 7, 79104 Freiburg, Germany
- Freiburg Institute for Advanced Studies, University of Freiburg, Albertstr. 19, 79104 Freiburg, Germany
- BIOSS Centre for Biological Signalling Studies, University of Freiburg, Schänzlestr. 18, 79104 Freiburg, Germany
- ZBSA Center for Biological Systems Analysis, University of Freiburg, Habsburgerstr. 49, 79104 Freiburg, Germany
| | - Susana Romao
- Viral Immunobiology, Institute of Experimental Immunology, University of Zürich, 8057 Zürich, Switzerland
| | - Urs Ziegler
- Center for Microscopy and Image Analysis, University of Zürich, 8057 Zürich, Switzerland
| | - Joern Dengjel
- Department of Dermatology, Medical Center, University of Freiburg, Hauptstr. 7, 79104 Freiburg, Germany
- Freiburg Institute for Advanced Studies, University of Freiburg, Albertstr. 19, 79104 Freiburg, Germany
- BIOSS Centre for Biological Signalling Studies, University of Freiburg, Schänzlestr. 18, 79104 Freiburg, Germany
- ZBSA Center for Biological Systems Analysis, University of Freiburg, Habsburgerstr. 49, 79104 Freiburg, Germany
| | - Christian Münz
- Viral Immunobiology, Institute of Experimental Immunology, University of Zürich, 8057 Zürich, Switzerland
- Corresponding author at: Institute of Experimental Immunology, University of Zürich, 8057 Zürich, Switzerland.
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7
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Abstract
A recent report from our group has described that upon engulfment of pathogens, a subset of phagosomes is formed to preserve antigens for prolonged presentation on MHC class II molecules. The distinctive feature of these particular vesicles is their coating with LC3/Atg8, a key component of the autophagy machinery. Here we discuss the possible outcomes of LC3-associated phagocytosis and its implications in the context of immunity.
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Affiliation(s)
- Susana Romao
- Viral Immunobiology; Institute of Experimental Immunology; University of Zürich; Zürich, Switzerland
| | - Christian Münz
- Viral Immunobiology; Institute of Experimental Immunology; University of Zürich; Zürich, Switzerland
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Hosokawa S, Koseki H, Nagashima M, Maeyama Y, Yomogida K, Mehr C, Rutledge M, Greenfeld H, Kaneki M, Tompkins RG, Martyn JAJ, Yasuhara SE. Title efficacy of phosphodiesterase 5 inhibitor on distant burn-induced muscle autophagy, microcirculation, and survival rate. Am J Physiol Endocrinol Metab 2013; 304:E922-33. [PMID: 23512808 DOI: 10.1152/ajpendo.00078.2013] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Skeletal muscle wasting is an exacerbating factor in the prognosis of critically ill patients. Using a systemic burn injury model in mice, we have established a role of autophagy in the resulting muscle wasting that is distant from the burn trauma. We provide evidence that burn injury increases the autophagy turnover in the distal skeletal muscle by conventional postmortem tissue analyses and by a novel in vivo microscopic method using an autophagy reporter gene (tandem fluorescent LC3). The effect of tadalafil, a phosphodiesterase 5 inhibitor (PDE5I), on burn-induced skeletal muscle autophagy is documented and extends our published results that PDE5Is attenuates muscle degeneration in a muscular dystrophy model. We also designed a translational experiment to examine the impact of PDE5I on whole body and demonstrated that PDE5I administration lessened muscle atrophy, mitigated microcirculatory disturbance, and improved the survival rate after burn injury.
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Affiliation(s)
- Sachiko Hosokawa
- Department of Anesthesiology and Critical Care and Pain Medicine, Shriners Hospital for Children, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, USA
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