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LC3 associated phagocytosis

Marc Herb, Alexander Gluschko, Michael Schramm
The macroautophagic/autophagic machinery cannot only target cell-endogenous components but also intracellular pathogenic bacteria such as Listeria monocytogenes. Listeria are targeted both by canonical autophagy and by a noncanonical form of autophagy referred to as LC3-associated phagocytosis (LAP). The molecular mechanisms involved and whether these processes contribute to anti-listerial immunity or rather provide Listeria with a replicative niche for persistent infection, however, remained unknown. Recently, using an in vivo mouse infection model, we have been able to demonstrate that Listeria in tissue macrophages are targeted exclusively by LAP...
June 20, 2018: Autophagy
Zhimin Duan, Qing Chen, Leilei Du, Jianbo Tong, Song Xu, Rong Zeng, Yuting Ma, Xu Chen, Min Li
Autophagy machinery has roles in the defense against microorganisms such as Candida albicans . Lipidated LC3, the marker protein of autophagy, participates in the elimination of C. albicans by forming a single-membrane phagosome; this process is called LC3-associated phagocytosis (LAP). However, the influence of C. albicans on autophagic flux is not clear. In this study, we found that C. albicans inhibited LC3 turnover in macrophages. After the phagocytosis of C. albicans in macrophages, we observed fewer acridine orange-positive vacuoles and RFP-GFP-LC3 puncta without colocalization with phagocytized C...
2018: Oxidative Medicine and Cellular Longevity
Irene Kyrmizi, Helena Ferreira, Agostinho Carvalho, Julio Alberto Landero Figueroa, Pavlos Zarmpas, Cristina Cunha, Tonia Akoumianaki, Kostas Stylianou, George S Deepe, George Samonis, João F Lacerda, António Campos, Dimitrios P Kontoyiannis, Nikolaos Mihalopoulos, Kyung J Kwon-Chung, Jamel El-Benna, Isabel Valsecchi, Anne Beauvais, Axel A Brakhage, Nuno M Neves, Jean-Paul Latge, Georgios Chamilos
LC3-associated phagocytosis (LAP) is a non-canonical autophagy pathway regulated by Rubicon, with an emerging role in immune homeostasis and antifungal host defence. Aspergillus cell wall melanin protects conidia (spores) from killing by phagocytes and promotes pathogenicity through blocking nicotinamide adenine dinucleotide phosphate (NADPH) oxidase-dependent activation of LAP. However, the signalling regulating LAP upstream of Rubicon and the mechanism of melanin-induced inhibition of this pathway remain incompletely understood...
May 30, 2018: Nature Microbiology
Gholamreza Fazeli, Maurice Stetter, Jaime N Lisack, Ann M Wehman
To understand how undifferentiated pluripotent cells cope with cell corpses, we examined the clearance of polar bodies born during female meiosis. We found that polar bodies lose membrane integrity and expose phosphatidylserine in Caenorhabditis elegans. Polar body signaling recruits engulfment receptors to the plasma membrane of embryonic blastomeres using the PI3K VPS-34, RAB-5 GTPase and the sorting nexin SNX-6. The second polar body is then phagocytosed using receptor-mediated engulfment pathways dependent on the Rac1 ortholog CED-10 but undergoes non-apoptotic programmed cell death independent of engulfment...
May 15, 2018: Cell Reports
S Upadhyay, E Mittal, J A Philips
Macrophages are first-line responders against microbes. The success of Mycobacterium tuberculosis (Mtb) rests upon its ability to convert these antimicrobial cells into a permissive cellular niche. This is a remarkable accomplishment, as the antimicrobial arsenal of macrophages is extensive. Normally bacteria are delivered to an acidic, degradative lysosome through one of several trafficking pathways, including LC3-associated phagocytosis (LAP) and autophagy. Once phagocytozed, the bacilli are subjected to reactive oxygen and nitrogen species, and they induce the expression of proinflammatory cytokines, which serve to augment host responses...
June 1, 2018: Pathogens and Disease
Anuradha Dhingra, Desiree Alexander, Juan Reyes-Reveles, Rachel Sharp, Kathleen Boesze-Battaglia
Microtubule-associated protein 1 light chain 3 (MAP1LC3), a human homologue of yeast Atg8, is an essential component of autophagy. LC3 plays a critical role in hybrid degradation pathways in which some but not all components of autophagy are coupled with phagocytosis in a process known as LC3-associated phagocytosis (LAP). LC3 exists as three highly homologous isoforms in human (LC3A, LC3B, and LC3C) with two of these (LC3A and LC3B) in mouse. LC3B predominated in both fetal and adult human retinal pigment epithelium (RPE) relative to LC3A and LC3C, while in mouse RPE and neural retina, LC3A and LC3B were expressed at approximately equivalent levels...
2018: Advances in Experimental Medicine and Biology
Kachiko Hayashi, Manabu Taura, Akiko Iwasaki
Toll-like receptor 9 (TLR9) recognizes DNA in endosomes and activates distinct signaling pathways to stimulate the production of proinflammatory cytokines and type I interferons (IFNs). The assembly of signaling platforms on microtubule-associated proteins 1A/1B-light chain 3 (LC3)-decorated endosomal vesicles is required to transduce TLR9 signals that stimulate the production of IFN but not interleukin-12 p40 (IL-12p40). LC3-associated phagocytosis (LAP), a form of noncanonical autophagy, is critical for the activation of interferon regulatory factor 7 (IRF7) and for IFN synthesis...
May 1, 2018: Science Signaling
Vasileios Oikonomou, Giorgia Renga, Antonella De Luca, Monica Borghi, Marilena Pariano, Matteo Puccetti, Giuseppe Paolicelli, Claudia Stincardini, Claudio Costantini, Andrea Bartoli, Teresa Zelante, Luigina Romani
Phagocytes fight fungi using canonical and noncanonical, also called LC3-associated phagocytosis (LAP), autophagy pathways. However, the outcomes of autophagy/LAP in shaping host immune responses appear to greatly vary depending on fungal species and cell types. By allowing efficient pathogen clearance and/or degradation of inflammatory mediators, autophagy proteins play a broad role in cellular and immune homeostasis during fungal infections. Indeed, defects in autophagic machinery have been linked with aberrant host defense and inflammatory states...
2018: Mediators of Inflammation
Alexander Gluschko, Marc Herb, Katja Wiegmann, Oleg Krut, Wolfram F Neiss, Olaf Utermöhlen, Martin Krönke, Michael Schramm
The intracellular pathogen Listeria monocytogenes (L.m.) is targeted by the autophagic machinery, but the molecular mechanisms involved and consequences for anti-listerial immunity remain enigmatic. Here, we demonstrate that L.m. infection of macrophages in vivo exclusively evokes LC3-associated phagocytosis (LAP), but not canonical autophagy, and that targeting of L.m. by LAP is required for anti-listerial immunity. The pathway leading to LAP induction in response to L.m. infection emanates from the β2 integrin Mac-1 (CR3, integrin αM β2 ), a receptor recognizing diverse microbial ligands...
March 14, 2018: Cell Host & Microbe
Kelly A Miller, Anna Cristina Garza-Mayers, Yiuka Leung, Marcia B Goldberg
Shigella species cause diarrhoea by invading and spreading through the epithelial layer of the human colon. The infection triggers innate immune responses in the host that the bacterium combats by translocating into the host cell cytosol via a type 3 secretion system bacterial effector proteins that interfere with host processes. We previously demonstrated that interaction of the Shigella type 3 secreted effector protein IcsB with the host protein Toca-1 inhibits the innate immune response microtubule-associated protein light-chain 3 (LC3)-associated phagocytosis, and that IcsB interaction with Toca-1 is required for inhibition of this host response...
April 2018: Microbiology
Stefan Köster, Thais Klevorn, Kadamba Papavinasasundaram, Christopher M Sassetti, Cynthia Portal-Celhay, Jennifer A Philips
Development of a new vaccine against tuberculosis is urgently needed. Recent work has demonstrated that two related LC3-associated trafficking pathways, autophagy and LC3-associated phagocytosis (LAP), enhance antigen presentation and might play a role in vaccine efficacy. Mycobacterium tuberculosis inhibits both LC3-trafficking pathways. Moreover, the vaccine strain, BCG, induces even less LC3-trafficking than M. tuberculosis, which may help explain its limited efficacy. To determine whether enhanced LC3-trafficking can improve efficacy of a live, attenuated M...
February 8, 2018: Vaccine
Katherine Fletcher, Rachel Ulferts, Elise Jacquin, Talitha Veith, Noor Gammoh, Julia M Arasteh, Ulrike Mayer, Simon R Carding, Thomas Wileman, Rupert Beale, Oliver Florey
A hallmark of macroautophagy is the covalent lipidation of LC3 and insertion into the double-membrane phagophore, which is driven by the ATG16L1/ATG5-ATG12 complex. In contrast, non-canonical autophagy is a pathway through which LC3 is lipidated and inserted into single membranes, particularly endolysosomal vacuoles during cell engulfment events such as LC3-associated phagocytosis. Factors controlling the targeting of ATG16L1 to phagophores are dispensable for non-canonical autophagy, for which the mechanism of ATG16L1 recruitment is unknown...
February 15, 2018: EMBO Journal
Stefan Köster, Sandeep Upadhyay, Jennifer A Philips
M. tuberculosis causes an enormous worldwide burden of disease. Its success depends upon subverting the antimicrobial capacity of macrophages. We have known for decades that M. tuberculosis impairs phagosomal trafficking to avoid lysosomal degradation, but the mechanism is unclear. Recent work has described a phagolysosomal pathway called LC3-associated phagocytosis (LAP), in which LC3 associates with microbe-containing phagosomes. Macrophage pathogen recognition receptors (PRRs) initiate LAP, and NADPH oxidase and RUBCN/RUBICON are required for LAP...
2018: Autophagy
Mark S Gresnigt, Katharina L Becker, Floris Leenders, M Fernanda Alonso, Xiaowen Wang, Jacques F Meis, Judith M Bain, Lars P Erwig, Frank L van de Veerdonk
Invasive aspergillosis mainly occurs in immunocompromised patients and is commonly caused by Aspergillus fumigatus, while A.nidulans is rarely the causative agent. However, in chronic granulomatous disease (CGD) patients, A. nidulans is a frequent cause of invasive aspergillosis and is associated with higher mortality. Immune recognition of A. nidulans was compared to A. fumigatus to offer an insight into why A. nidulans infections are prevalent in CGD. Live cell imaging with J774A.1 macrophage-like cells and LC3-GFP-mCherry bone marrow-derived macrophages (BMDMs) revealed that phagocytosis of A...
2018: Journal of Innate Immunity
Sing-Wai Wong, Payel Sil, Jennifer Martinez
Rubicon (Rubcn) was initially identified as a component of the Class III PI3K complex and a negative regulator of canonical autophagy and endosomal trafficking. However, Rubicon has attracted the most notoriety because of its critical role in LC3-associated phagocytosis (LAP), a form of noncanonical autophagy that utilizes some components of the autophagy machinery to process extracellular cargo. Additionally, Rubicon has been identified as a key modulator of the inflammatory response and viral replication...
April 2018: FEBS Journal
Stefan Schille, Peter Crauwels, Rebecca Bohn, Katrin Bagola, Paul Walther, Ger van Zandbergen
Phagocytosis is essential for uptake and elimination of pathogenic microorganisms. Autophagy is a highly conserved mechanism for incorporation of cellular constituents to replenish nutrients by degradation. Recently, parts of the autophagy machinery - above all microtubule-associated protein 1 light chain 3 (LC3) - were found to be specifically recruited to phagosomal membranes resulting in phagosome-lysosome fusion and efficient degradation of internalized cargo in a process termed LC3-associated phagocytosis (LAP)...
November 21, 2017: International Journal of Medical Microbiology: IJMM
Aïcha Bah, Isabelle Vergne
Autophagy is a well-conserved lysosomal degradation pathway that plays key roles in bacterial infections. One of the most studied is probably xenophagy, the selective capture and degradation of intracellular bacteria by lysosomes. However, the impact of autophagy goes beyond xenophagy and involves intensive cross-talks with other host defense mechanisms. In addition, autophagy machinery can have non-canonical functions such as LC3-associated phagocytosis. In this review, we intend to summarize the current knowledge on the many functions of autophagy proteins in cell defenses with a focus on bacteria-macrophage interaction...
2017: Frontiers in Immunology
Yu Matsuzawa-Ishimoto, Seungmin Hwang, Ken Cadwell
The cellular degradative pathway of autophagy has a fundamental role in immunity. Here, we review the function of autophagy and autophagy proteins in inflammation. We discuss how the autophagy machinery controls the burden of infectious agents while simultaneously limiting inflammatory pathologies, which often involves processes that are distinct from conventional autophagy. Among the newly emerging processes we describe are LC3-associated phagocytosis and targeting by autophagy proteins, both of which require many of the same proteins that mediate conventional autophagy...
April 26, 2018: Annual Review of Immunology
Juliete A F Silva, Alexandre Bruni-Cardoso, Taize M Augusto, Danilo M Damas-Souza, Guilherme O Barbosa, Sérgio L Felisbino, Dagmar R Stach-Machado, Hernandes F Carvalho
BACKGROUND: Androgen deprivation results in massive apoptosis in the prostate gland. Macrophages are actively engaged in phagocytosing epithelial cell corpses. However, it is unknown whether microtubule-associated protein 1 light chain 3 alpha (LC3)-associated phagocytosis (LAP) is involved and contribute to prevent inflammation. METHODS: Flow cytometry, RT-PCR and immunohistochemistry were used to characterize the macrophage subpopulation residing in the epithelial layer of the rat ventral prostate (VP) after castration...
February 2018: Prostate
Dimitra Lamprinaki, Gemma Beasy, Aleksandra Zhekova, Alexandra Wittmann, Steve James, Jo Dicks, Yoichiro Iwakura, Shinobu Saijo, Xiaomin Wang, Chung-Wai Chow, Ian Roberts, Tamas Korcsmaros, Ulrike Mayer, Thomas Wileman, Norihito Kawasaki
The human fungal microbiota known as mycobiota is increasingly recognized as a critical factor in human gut health and disease. Non-pathogenic commensal yeasts such as Saccharomyces cerevisiae promote homeostasis in the gut, whereas dysbiosis of the gut mycobiota is associated with inflammation. Glycan-binding receptors (lectins) are key host factors in host-mycobiota interaction in the gut. They are expressed on immune cells such as dendritic cells (DCs) and recognize fungal polysaccharides. This interaction is imperative to mount appropriate immune responses for immune homeostasis in the gut as well as clearance of fungal pathogens...
2017: Frontiers in Immunology
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