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Wu Y, Taisne C, Mahtal N, Forrester A, Lussignol M, Cintrat JC, Esclatine A, Gillet D, Barbier J. Autophagic Degradation Is Involved in Cell Protection against Ricin Toxin. Toxins (Basel) 2023; 15:toxins15050304. [PMID: 37235339 DOI: 10.3390/toxins15050304] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Revised: 04/19/2023] [Accepted: 04/20/2023] [Indexed: 05/28/2023] Open
Abstract
Autophagy is a complex and highly regulated degradative process, which acts as a survival pathway in response to cellular stress, starvation and pathogen infection. Ricin toxin is a plant toxin produced by the castor bean and classified as a category B biothreat agent. Ricin toxin inhibits cellular protein synthesis by catalytically inactivating ribosomes, leading to cell death. Currently, there is no licensed treatment for patients exposed to ricin. Ricin-induced apoptosis has been extensively studied; however, whether its intoxication via protein synthesis inhibition affects autophagy is not yet resolved. In this work, we demonstrated that ricin intoxication is accompanied by its own autophagic degradation in mammalian cells. Autophagy deficiency, by knocking down ATG5, attenuates ricin degradation, thus aggravating ricin-induced cytotoxicity. Additionally, the autophagy inducer SMER28 (Small Molecule Enhancer 28) partially protects cells against ricin cytotoxicity, an effect not observed in autophagy-deficient cells. These results demonstrate that autophagic degradation acts as a survival response of cells against ricin intoxication. This suggests that stimulation of autophagic degradation may be a strategy to counteract ricin intoxication.
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Affiliation(s)
- Yu Wu
- Université Paris-Saclay, CEA, INRAE, Département Médicaments et Technologies pour la Santé (DMTS), SIMoS, Gif-sur-Yvette 91191, France
- Institute of Immunology, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China (USTC), Hefei 230001, China
| | - Clémence Taisne
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette 91198, France
| | - Nassim Mahtal
- Université Paris-Saclay, CEA, INRAE, Département Médicaments et Technologies pour la Santé (DMTS), SIMoS, Gif-sur-Yvette 91191, France
| | - Alison Forrester
- Research Unit of Biochemistry and Cell Biology (URBC), Namur Research Institute for Life Sciences (NARILIS), University of Namur, 5000 Namur, Belgium
| | - Marion Lussignol
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette 91198, France
| | - Jean-Christophe Cintrat
- Université Paris-Saclay, CEA, INRAE, Médicaments et Technologies pour la Santé (DMTS), SCBM, Gif-sur-Yvette 91191, France
| | - Audrey Esclatine
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette 91198, France
| | - Daniel Gillet
- Université Paris-Saclay, CEA, INRAE, Département Médicaments et Technologies pour la Santé (DMTS), SIMoS, Gif-sur-Yvette 91191, France
| | - Julien Barbier
- Université Paris-Saclay, CEA, INRAE, Département Médicaments et Technologies pour la Santé (DMTS), SIMoS, Gif-sur-Yvette 91191, France
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2
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Khayati K, Bhatt V, Hu ZS, Fahumy S, Luo X, Guo JY. Autophagy compensates for Lkb1 loss to maintain adult mice homeostasis and survival. eLife 2020; 9:62377. [PMID: 33236987 PMCID: PMC7714393 DOI: 10.7554/elife.62377] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2020] [Accepted: 11/24/2020] [Indexed: 12/12/2022] Open
Abstract
Liver kinase B1 (LKB1), also known as serine/threonine kinase 11 (STK11) is the major energy sensor for cells to respond to metabolic stress. Autophagy degrades and recycles proteins, macromolecules, and organelles for cells to survive starvation. To assess the role and cross-talk between autophagy and Lkb1 in normal tissue homeostasis, we generated genetically engineered mouse models where we can conditionally delete Stk11 and autophagy essential gene, Atg7, respectively or simultaneously, throughout the adult mice. We found that Lkb1 was essential for the survival of adult mice, and autophagy activation could temporarily compensate for the acute loss of Lkb1 and extend mouse life span. We further found that acute deletion of Lkb1 in adult mice led to impaired intestinal barrier function, hypoglycemia, and abnormal serum metabolism, which was partly rescued by the Lkb1 loss-induced autophagy upregulation via inhibiting p53 induction. Taken together, we demonstrated that autophagy and Lkb1 work synergistically to maintain adult mouse homeostasis and survival.
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Affiliation(s)
- Khoosheh Khayati
- Rutgers Cancer Institute of New Jersey, New Brunswick, United States
| | - Vrushank Bhatt
- Rutgers Cancer Institute of New Jersey, New Brunswick, United States
| | | | - Sajid Fahumy
- Rutgers Cancer Institute of New Jersey, New Brunswick, United States
| | - Xuefei Luo
- Rutgers Cancer Institute of New Jersey, New Brunswick, United States
| | - Jessie Yanxiang Guo
- Rutgers Cancer Institute of New Jersey, New Brunswick, United States.,Department of Medicine, Rutgers Robert Wood Johnson Medical School, New Brunswick, United States.,Department of Chemical Biology, Rutgers Ernest Mario School of Pharmacy, Piscataway, United States
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3
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Glucosyltransferase Activity of Clostridium difficile Toxin B Triggers Autophagy-mediated Cell Growth Arrest. Sci Rep 2017; 7:10532. [PMID: 28874882 PMCID: PMC5585374 DOI: 10.1038/s41598-017-11336-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Accepted: 07/04/2017] [Indexed: 12/19/2022] Open
Abstract
Autophagy is a bulk cell-degradation process that occurs through the lysosomal machinery, and many reports have shown that it participates in microbial pathogenicity. However, the role of autophagy in Clostridium difficile infection (CDI), the leading cause of antibiotics-associated diarrhea, pseudomembranous colitis and even death in severe cases, is not clear. Here we report that the major virulent factor toxin B (TcdB) of Clostridium difficile elicits a strong autophagy response in host cells through its glucosyltransferase activity. Using a variety of autophagy-deficient cell lines, i.e. HeLa/ATG7−/−, MEF/atg7−/−, MEF/tsc2−/−, we demonstrate that toxin-triggered autophagy inhibits host cell proliferation, which contributes to TcdB-caused cytopathic biological effects. We further show that both the PI3K complex and mTOR pathway play important roles in this autophagy induction process and consequent cytopathic event. Although the glucosyltransferase activity of TcdB is responsible for inducing both cell rounding and autophagy, there is no evidence suggesting the causal relationship between these two events. Taken together, our data demonstrate for the first time that the glucosyltransferase enzymatic activity of a pathogenic bacteria is responsible for host autophagy induction and the following cell growth arrest, providing a new paradigm for the role of autophagy in host defense mechanisms upon pathogenic infection.
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4
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You L, Jin S, Zhu L, Qian W. Autophagy, autophagy-associated adaptive immune responses and its role in hematologic malignancies. Oncotarget 2017; 8:12374-12388. [PMID: 27902471 PMCID: PMC5355352 DOI: 10.18632/oncotarget.13583] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2016] [Accepted: 11/11/2016] [Indexed: 12/19/2022] Open
Abstract
Autophagy is a tightly regulated catabolic process that leads to the degradation of cytoplasmatic components such as aggregated/misfolded proteins and organelles through the lysosomal machinery. Recent studies suggest that autophagy plays such a role in the context of the anti-tumor immune response, make it an attractive target for cancer immunotherapy. Defective autophagy in hematopoietic stem cells may contribute to the development of hematologic malignancies, including leukemia, myelodysplastic syndrome, and lymphoproliferative disorder. In blood cancer cells, autophagy can either result in chemoresistance or induce autophagic cell death that may act as immunogenic. Based on the successful experimental findings in vitro and in vivo, clinical trials of autophagy inhibitor such as hydroxychloroquine in combination with chemotherapy in patients with blood cancers are currently underway. However, autophagy inactivation might impair autophagy-triggered anticancer immunity, whereas induction of autophagy might become an effective immunotherapy. These aspects are discussed in this review together with a brief introduction to the autophagic molecular machinery and its roles in hematologic malignancies.
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Affiliation(s)
- Liangshun You
- Department of Hematology, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou 310003, P.R. China
| | - Shenhe Jin
- Department of Hematology, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou 310003, P.R. China
| | - Li Zhu
- Department of Hematology, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou 310003, P.R. China
| | - Wenbin Qian
- Department of Hematology, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou 310003, P.R. China
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5
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Ramachandran G, Gade P, Tsai P, Lu W, Kalvakolanu DV, Rosen GM, Cross AS. Potential role of autophagy in the bactericidal activity of human PMNs for Bacillus anthracis. Pathog Dis 2015; 73:ftv080. [PMID: 26424808 DOI: 10.1093/femspd/ftv080] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/22/2015] [Indexed: 12/19/2022] Open
Abstract
Bacillus anthracis, the causative agent of anthrax, is acquired by mammalian hosts from the environment, as quiescent endospores. These endospores must germinate inside host cells, forming vegetative bacilli, before they can express the virulence factors that enable them to evade host defenses and disseminate throughout the body. While the role of macrophages and dendritic cells in this initial interaction has been established, the role of polymorphonuclear leukocytes (PMNs) has not been adequately defined. We discovered that while B. anthracis 34F2 Sterne endospores germinate poorly within non-activated human PMNs, these phagocytes exhibit rapid microbicidal activity toward the outgrown vegetative bacilli, independent of superoxide and nitric oxide. These findings suggest that a non-free radical pathway kills B. anthracis bacilli. We also find in PMNs an autophagic mechanism of bacterial killing based on the rapid induction of LC-3 conversion, beclin-1 expression, sequestosome 1 (SQSTM1) degradation and inhibition of bactericidal activity by the inhibitor, 3-methyladenine. These findings extend to PMNs an autophagic bactericidal mechanism previously described for other phagocytes.
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Affiliation(s)
- Girish Ramachandran
- Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Padmaja Gade
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Pei Tsai
- Department of Pharmaceutical Sciences, and the Center for EPR Imaging In Vivo Physiology, University of Maryland School of Pharmacy, Baltimore, MD 21201, USA
| | - Wuyuan Lu
- Institute of Human Virology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Dhananjaya V Kalvakolanu
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Gerald M Rosen
- Department of Pharmaceutical Sciences, and the Center for EPR Imaging In Vivo Physiology, University of Maryland School of Pharmacy, Baltimore, MD 21201, USA
| | - Alan S Cross
- Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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6
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Zilbermintz L, Leonardi W, Jeong SY, Sjodt M, McComb R, Ho CLC, Retterer C, Gharaibeh D, Zamani R, Soloveva V, Bavari S, Levitin A, West J, Bradley KA, Clubb RT, Cohen SN, Gupta V, Martchenko M. Identification of agents effective against multiple toxins and viruses by host-oriented cell targeting. Sci Rep 2015; 5:13476. [PMID: 26310922 PMCID: PMC4550849 DOI: 10.1038/srep13476] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Accepted: 07/28/2015] [Indexed: 01/25/2023] Open
Abstract
A longstanding and still-increasing threat to the effective treatment of infectious diseases is resistance to antimicrobial countermeasures. Potentially, the targeting of host proteins and pathways essential for the detrimental effects of pathogens offers an approach that may discover broad-spectrum anti-pathogen countermeasures and circumvent the effects of pathogen mutations leading to resistance. Here we report implementation of a strategy for discovering broad-spectrum host-oriented therapies against multiple pathogenic agents by multiplex screening of drugs for protection against the detrimental effects of multiple pathogens, identification of host cell pathways inhibited by the drug, and screening for effects of the agent on other pathogens exploiting the same pathway. We show that a clinically used antimalarial drug, Amodiaquine, discovered by this strategy, protects host cells against infection by multiple toxins and viruses by inhibiting host cathepsin B. Our results reveal the practicality of discovering broadly acting anti-pathogen countermeasures that target host proteins exploited by pathogens.
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Affiliation(s)
| | | | - Sun-Young Jeong
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305
| | - Megan Sjodt
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA, 90095
| | - Ryan McComb
- Keck Graduate Institute, Claremont, CA 91711
| | - Chi-Lee C Ho
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, CA, 90095
| | - Cary Retterer
- US Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, MD, 21702
| | - Dima Gharaibeh
- US Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, MD, 21702
| | - Rouzbeh Zamani
- US Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, MD, 21702
| | - Veronica Soloveva
- US Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, MD, 21702
| | - Sina Bavari
- US Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, MD, 21702
| | | | - Joel West
- Keck Graduate Institute, Claremont, CA 91711
| | - Kenneth A Bradley
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, CA, 90095
| | - Robert T Clubb
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA, 90095
| | - Stanley N Cohen
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305
| | - Vivek Gupta
- Keck Graduate Institute, Claremont, CA 91711
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7
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Tang Y, Li F, Tan B, Liu G, Kong X, Hardwidge PR, Yin Y. Enterotoxigenic Escherichia coli infection induces intestinal epithelial cell autophagy. Vet Microbiol 2014; 171:160-4. [PMID: 24742948 DOI: 10.1016/j.vetmic.2014.03.025] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Revised: 03/17/2014] [Accepted: 03/22/2014] [Indexed: 10/25/2022]
Abstract
The morbidity and mortality in piglets caused by enterotoxigenic Escherichia coli (ETEC) results in large economic losses to the swine industry, but the precise pathogenesis of ETEC-associated diseases remains unknown. Intestinal epithelial cell autophagy serves as a host defense against pathogens. We found that ETEC induced autophagy, as measured by both the increased punctae distribution of GFP-LC3 and the enhanced conversion of LC3-I to LC3-II. Inhibiting autophagy resulted in decreased survival of IPEC-1 cells infected with ETEC. ETEC triggered autophagy in IPEC-1 cells through a pathway involving the mammalian target of rapamycin (mTOR), the extracellular signal-regulated kinases 1/2 (ERK1/2), and the AMP-activated protein kinase (AMPK).
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Affiliation(s)
- Yulong Tang
- Institute of Subtropical Agriculture, Chinese Academy of Sciences, Research Center of Healthy Breeding Livestock & Poultry, Hunan Engineering & Research Center of Animal & Poultry Science, Key Lab Agro-ecology Processing Subtropical Region, Scientific Observational and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Changsha, Hunan, People's Republic of China.
| | - Fengna Li
- Institute of Subtropical Agriculture, Chinese Academy of Sciences, Research Center of Healthy Breeding Livestock & Poultry, Hunan Engineering & Research Center of Animal & Poultry Science, Key Lab Agro-ecology Processing Subtropical Region, Scientific Observational and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Changsha, Hunan, People's Republic of China
| | - Bie Tan
- Institute of Subtropical Agriculture, Chinese Academy of Sciences, Research Center of Healthy Breeding Livestock & Poultry, Hunan Engineering & Research Center of Animal & Poultry Science, Key Lab Agro-ecology Processing Subtropical Region, Scientific Observational and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Changsha, Hunan, People's Republic of China
| | - Gang Liu
- Institute of Subtropical Agriculture, Chinese Academy of Sciences, Research Center of Healthy Breeding Livestock & Poultry, Hunan Engineering & Research Center of Animal & Poultry Science, Key Lab Agro-ecology Processing Subtropical Region, Scientific Observational and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Changsha, Hunan, People's Republic of China
| | - Xiangfeng Kong
- Institute of Subtropical Agriculture, Chinese Academy of Sciences, Research Center of Healthy Breeding Livestock & Poultry, Hunan Engineering & Research Center of Animal & Poultry Science, Key Lab Agro-ecology Processing Subtropical Region, Scientific Observational and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Changsha, Hunan, People's Republic of China
| | - Philip R Hardwidge
- Department of Diagnostic Medicine/Pathobiology, Kansas State University, Manhattan, KS, USA
| | - Yulong Yin
- Institute of Subtropical Agriculture, Chinese Academy of Sciences, Research Center of Healthy Breeding Livestock & Poultry, Hunan Engineering & Research Center of Animal & Poultry Science, Key Lab Agro-ecology Processing Subtropical Region, Scientific Observational and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Changsha, Hunan, People's Republic of China.
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8
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Puleston DJ, Simon AK. Autophagy in the immune system. Immunology 2014; 141:1-8. [PMID: 23991647 PMCID: PMC3893844 DOI: 10.1111/imm.12165] [Citation(s) in RCA: 115] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2013] [Revised: 08/27/2013] [Accepted: 08/28/2013] [Indexed: 12/12/2022] Open
Abstract
Autophagy is an intracellular homeostatic mechanism important for the degradation of waste components from the cytoplasm in acidic lysosomal compartments. Originally, surplus parts of the cytoplasm that acted as targets for autophagy were thought to comprise cellular organelles and proteins, but this has now extended to include a range of pathogens with particular emphasis on intracellular bacteria. The finding that autophagy can sequester intracellular bacteria and mediate their destruction has opened the door to a wider role for autophagy as an effector arm of the immune system. In innate immunity, autophagy works downstream of pattern recognition receptors where it facilitates a number of effector responses, including cytokine production and phagocytosis. Autophagy is also able to intersect pathways of innate and adaptive immunity through its potential to deliver antigens for antigen presentation. Autophagy provides a substantial source of antigens for loading onto MHC class II molecules and it may be important in dendritic cells for cross-priming to CD8(+) T cells. In lymphocytes, autophagy is essential for cell survival and homeostasis, particularly in T cells. In the thymus, autophagy can modulate the selection of certain CD4(+) T-cell clones while in the bone marrow autophagy is needed for B-cell development at specific stages. However, large holes exist in our knowledge as to how autophagy regulates, and is regulated by, the immune system and it is important to now apply what we have gleaned from in vitro studies to how autophagy operates in vivo in the setting of natural infection.
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Affiliation(s)
- Daniel J Puleston
- MRC Human Immunology Unit, The Weatherall Institute of Molecular Medicine, University of OxfordOxford, UK
| | - Anna Katharina Simon
- MRC Human Immunology Unit, The Weatherall Institute of Molecular Medicine, University of OxfordOxford, UK
- The BRC Translational Immunology Lab, NIHR, The John Radcliffe Hospital, University of OxfordOxford, UK
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9
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Greenfield LK, Jones NL. Modulation of autophagy by Helicobacter pylori and its role in gastric carcinogenesis. Trends Microbiol 2013; 21:602-12. [PMID: 24156875 DOI: 10.1016/j.tim.2013.09.004] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2013] [Revised: 09/09/2013] [Accepted: 09/12/2013] [Indexed: 02/06/2023]
Abstract
Helicobacter pylori infection represents the strongest known risk factor for the development of gastric cancer. The vacuolating cytotoxin (VacA) plays a key role in disease pathogenesis by exerting pleiotrophic effects on the host. One effect of acute VacA exposure is the induction of autophagy. However, prolonged exposure to the toxin disrupts autophagy by preventing maturation of the autolysosome. Novel insights into the mechanism and consequences of this phenomenon have emerged, but many aspects remain largely unknown. Current evidence supports a scenario in which H. pylori-suppressed autophagy facilitates intracellular survival and persistence of the pathogen, while also generating an environment favoring carcinogenesis.
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Affiliation(s)
- Laura K Greenfield
- Departments of Paediatrics and Physiology, University of Toronto, Cell Biology Program, Research Institute, The Hospital for Sick Children, 555 University Avenue, Toronto, Ontario, M5G 1X8, Canada
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10
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Abstract
Autophagy is a conserved cellular degradative pathway that is now established to be a vital part of the host immune response to microbial infection. Autophagy can directly eliminate intracellular pathogens by mediating their delivery to lysosomes. Canonical autophagy is characterized by the formation of a double-membrane autophagosome and the involvement of over 35 autophagy-related proteins (Atgs), including a commonly used autophagosome marker in mammalian cells, LC3. Recent studies have shown that a subset of autophagy components can lead to LC3 conjugation onto phagosomes. This process of LC3-associated phagocytosis (LAP) results in the degradation of the cargo by promoting phagosome fusion with lysosomes. Other components of the autophagy machinery also play roles in immunity that are distinct from the canonical autophagy and LAP pathways. This minireview highlights the complicated relationship between autophagy components and intracellular bacteria, including bacterial targeting mechanisms and the interaction between autophagy and effectors/toxins secreted by bacteria.
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Affiliation(s)
- Marija Cemma
- Cell Biology Program, Hospital for Sick Children, Toronto, Ontario M5G1X8, Canada
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11
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Gong L, Devenish RJ, Prescott M. Autophagy as a macrophage response to bacterial infection. IUBMB Life 2012; 64:740-7. [PMID: 22815102 DOI: 10.1002/iub.1070] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2012] [Accepted: 06/13/2012] [Indexed: 01/07/2023]
Abstract
The macrophage is a key component of host defense mechanisms against pathogens. In addition to the phagocytosis of bacteria and secretion of proinflammatory mediators by macrophages, autophagy, a process involved in turnover of cellular material, is a recently identified component of the immune response to bacterial infection. Despite the bactericidal effect of autophagy, some species of intracellular bacteria are able to survive by using one or more strategies to avoid host autophagic attack. Here, we review the latest findings on the interactions between bacteria and autophagy in macrophages.
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Affiliation(s)
- Lan Gong
- Department of Biochemistry and Molecular Biology, Monash University, Clayton Campus, Vic., Australia
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12
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Liévin-Le Moal V, Comenge Y, Ruby V, Amsellem R, Nicolas V, Servin AL. Secreted autotransporter toxin (Sat) triggers autophagy in epithelial cells that relies on cell detachment. Cell Microbiol 2011; 13:992-1013. [PMID: 21501364 DOI: 10.1111/j.1462-5822.2011.01595.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The secreted autotransporter toxin, Sat, which belongs to the subfamily of serine protease autotransporters of Enterobacteriaceae, acts as a virulence factor in extraintestinal and intestinal pathogenic strains of Escherichia coli. We observed that HeLa cells exposed to the cell-free culture supernatant of recombinant strain AAEC185p(Sat-IH11128) producing the Sat toxin (CFCS(Sat) ), displayed dramatic disorganization of the F-actin cytoskeleton before loosening cell-to-cell junctions and detachment. Examination of the effect of Sat on GFP-microtubule-associated protein light chain 3 (LC3) HeLa cells revealed that CFCS(Sat) -induced autophagy follows CFCS(Sat) -induced F-actin cytoskeleton rearrangement. The induced autophagy shows an acceleration of the autophagy flux soon after Sat treatment, followed later by a blockade of the flux leading to the accumulation of large GFP-LC3-positive vacuoles in the cell cytoplasm. CFCS(Sat) did not induce cell detachment in autophagy-deficient mouse embryonic fibroblasts in contrast with wild-type mouse embryonic fibroblasts. The CFCS(Sat) -induced large GFP-LC3 dots do not display the characteristics of autophagolysosomes including expression of cathepsin D and Lamp-1 and 2 proteins, and Lysotracker Red- and DQ-BSA-positive labelling. We provide evidences that CFCS(Sat) -induced autophagy is not a cell response intended to get rid of the intracellular toxin. By a pharmacological blockers approach, we found that the blockade of Erk1/2 and p38 MAPKs, but not JNK, inhibited the CFCS(Sat) -induced autophagy and cell detachment whereas phosphatidylinositol-3 kinase blockers inhibiting canonical autophagy were inactive. When attached CFCS(Sat) -treated cells start to detach they showed caspase-independent cell death and rearrangements of the focal adhesion-associated vinculin and paxillin. Collectively, our results support that Sat triggers autophagy in epithelial cells that relies on its cell-detachment effect.
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Affiliation(s)
- Vanessa Liévin-Le Moal
- INSERM, UMR 756 Signalisation and Physiopathology of Epithelial cells, IFR 141 Plateforme Imagerie cellulaire Université Paris-Sud, Faculté de Pharmacie, Châtenay-Malabry, France
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13
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Contribution of lethal toxin and edema toxin to the pathogenesis of anthrax meningitis. Infect Immun 2011; 79:2510-8. [PMID: 21518787 DOI: 10.1128/iai.00006-11] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Bacillus anthracis is a Gram-positive spore-forming bacterium that causes anthrax disease in humans and animals. Systemic infection is characterized by septicemia, toxemia, and meningitis, the main neurological complication associated with high mortality. We have shown previously that B. anthracis Sterne is capable of blood-brain barrier (BBB) penetration, establishing the classic signs of meningitis, and that infection is dependent on the expression of both major anthrax toxins, lethal toxin (LT) and edema toxin (ET). Here we further investigate the contribution of the individual toxins to BBB disruption using isogenic toxin mutants deficient in lethal factor, ΔLF, and edema factor, ΔEF. Acute infection with B. anthracis Sterne and the ΔLF mutant resulted in disruption of human brain microvascular endothelial cell (hBMEC) monolayer integrity and tight junction protein zona occludens-1, while the result for cells infected with the ΔEF mutant was similar to that for the noninfected control. A significant decrease in bacterial invasion of BBB endothelium in vitro was observed during infection with the ΔLF strain, suggesting a prominent role for LT in promoting BBB interaction. Further, treatment of hBMECs with purified LT or chemicals that mimic LT action on host signaling pathways rescued the hypoinvasive phenotype of the ΔLF mutant and resulted in increased bacterial uptake. We also observed that toxin expression reduced bacterial intracellular survival by inducing the bulk degradative autophagy pathway in host cells. Finally, in a murine model of anthrax meningitis, mice infected with the ΔLF mutant exhibited no mortality, brain bacterial load, or evidence of meningitis compared to mice infected with the parental or ΔEF strains.
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14
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Essential role of the redox-sensitive kinase p66shc in determining energetic and oxidative status and cell fate in neuronal preconditioning. J Neurosci 2010; 30:5242-52. [PMID: 20392947 DOI: 10.1523/jneurosci.6366-09.2010] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Ischemic preconditioning is a phenomenon in which low-level stressful stimuli upregulate endogenous defensive programs, resulting in subsequent resistance to otherwise lethal injuries. We previously observed that signal transduction systems typically associated with neurodegeneration such as caspase activation are requisite events for the expression of tolerance and induction of HSP70. In this work, we sought to determine the extent and duration of oxidative and energetic dysfunction as well as the role of effector kinases on metabolic function in preconditioned cells. Using an in vitro neuronal culture model, we observed a robust increase in Raf and p66(Shc) activation within 1 h of preconditioning. Total ATP content decreased by 25% 3 h after preconditioning but returned to baseline by 24 h. Use of a free radical spin trap or p66(shc) inhibitor increased ATP content whereas a Raf inhibitor had no effect. Phosphorylated p66(shc) rapidly relocalized to the mitochondria and in the absence of activated p66(shc), autophagic processing increased. The constitutively expressed chaperone HSC70 relocalized to autophagosomes. Preconditioned cells experience significant total oxidative stress measured by F(2)-isoprostanes and neuronal stress evaluated by F(4)-neuroprostane measurement. Neuroprostane levels were enhanced in the presence of Shc inhibitors. Finally, we found that inhibiting either p66(shc) or Raf blocked neuroprotection afforded by preconditioning as well as upregulation of HSP70, suggesting both kinases are critical for preconditioning but function in fundamentally different ways. This is the first work to demonstrate the essential role of p66(shc) in mediating requisite mitochondrial and energetic compensation after preconditioning and suggests a mechanism by which protein and organelle damage mediated by ROS can increase HSP70.
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Sumpter R, Levine B. Autophagy and innate immunity: triggering, targeting and tuning. Semin Cell Dev Biol 2010; 21:699-711. [PMID: 20403453 DOI: 10.1016/j.semcdb.2010.04.003] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2010] [Revised: 04/06/2010] [Accepted: 04/08/2010] [Indexed: 02/06/2023]
Abstract
Autophagy is a conserved catabolic stress response pathway that is increasingly recognized as an important component of both innate and acquired immunity to pathogens. The activation of autophagy during infection not only provides cell-autonomous protection through lysosomal degradation of invading pathogens (xenophagy), but also regulates signaling by other innate immune pathways. This review will focus on recent advances in our understanding of three major areas of the interrelationship between autophagy and innate immunity, including how autophagy is triggered during infection, how invading pathogens are targeted to autophagosomes, and how the autophagy pathway participates in "tuning" the innate immune response.
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Affiliation(s)
- Rhea Sumpter
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
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Ha SD, Ham B, Mogridge J, Saftig P, Lin S, Kim SO. Cathepsin B-mediated autophagy flux facilitates the anthrax toxin receptor 2-mediated delivery of anthrax lethal factor into the cytoplasm. J Biol Chem 2009; 285:2120-9. [PMID: 19858192 DOI: 10.1074/jbc.m109.065813] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Anthrax lethal toxin (LeTx) is a virulence factor secreted by Bacillus anthracis and has direct cytotoxic effects on most cells once released into the cytoplasm. The cytoplasmic delivery of the proteolytically active component of LeTx, lethal factor (LF), is carried out by the transporter component, protective antigen, which interacts with either of two known surface receptors known as anthrax toxin receptor (ANTXR) 1 and 2. We found that the cytoplasmic delivery of LF by ANTXR2 was mediated by cathepsin B (CTSB) and required lysosomal fusion with LeTx-containing endosomes. Also, binding of protective antigen to ANXTR1 or -2 triggered autophagy, which facilitated the cytoplasmic delivery of ANTXR2-associated LF. We found that whereas cells treated with the membrane-permeable CTSB inhibitor CA074-Me- or CTSB-deficient cells had no defect in fusion of LC3-containing autophagic vacuoles with lysosomes, autophagic flux was significantly delayed. These results suggested that the ANTXR2-mediated cytoplasmic delivery of LF was enhanced by CTSB-dependent autophagic flux.
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Affiliation(s)
- Soon-Duck Ha
- Department of Microbiology and Immunology, Siebens-Drake Research Institute, University of Western Ontario, London, Ontario N6G2V4, Canada
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Abstract
Autophagy adjusts cellular biomass and function in response to diverse stimuli, including infection. Autophagy plays specific roles in shaping immune system development, fueling host innate and adaptive immune responses, and directly controlling intracellular microbes as a cell-autonomous innate defense. As an evolutionary counterpoint, intracellular pathogens have evolved to block autophagic microbicidal defense and subvert host autophagic responses for their survival or growth. The ability of eukaryotic pathogens to deploy their own autophagic machinery may also contribute to microbial pathogenesis. Thus, a complex interplay between autophagy and microbial adaptations against autophagy governs the net outcome of host-microbe encounters.
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