Abstract
Autophagy is regulated for IFN-gamma-mediated antimicrobial efficacy; however, its molecular effects for IFN-gamma signaling are largely unknown. Here, we show that autophagy facilitates IFN-gamma-activated Jak2-STAT1. IFN-gamma induces autophagy in wild-type but not in autophagy protein 5 (Atg5(-/-))-deficient mouse embryonic fibroblasts (MEFs), and, autophagy-dependently, IFN-gamma induces IFN regulatory factor 1 and cellular inflammatory responses. Pharmacologically inhibiting autophagy using 3-methyladenine, a known inhibitor of class III phosphatidylinositol 3-kinase, confirms these effects. Either Atg5(-/-) or Atg7(-/-) MEFs are, independent of changes in IFN-gamma receptor expression, resistant to IFN-gamma-activated Jak2-STAT1, which suggests that autophagy is important for IFN-gamma signal transduction. Lentivirus-based short hairpin RNA for Atg5 knockdown confirmed the importance of autophagy for IFN-gamma-activated STAT1. Without autophagy, reactive oxygen species increase and cause SHP2 (Src homology-2 domain-containing phosphatase 2)-regulated STAT1 inactivation. Inhibiting SHP2 reversed both cellular inflammation and the IFN-gamma-induced activation of STAT1 in Atg5(-/-) MEFs. Our study provides evidence that there is a link between autophagy and both IFN-gamma signaling and cellular inflammation and that autophagy, because it inhibits the expression of reactive oxygen species and SHP2, is pivotal for Jak2-STAT1 activation.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Adenine / analogs & derivatives
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Adenine / pharmacology
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Animals
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Autophagy / physiology*
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Autophagy-Related Protein 5
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Autophagy-Related Protein 7
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Cells, Cultured
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Embryo, Mammalian / cytology
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Embryo, Mammalian / metabolism
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Enzyme Inhibitors / pharmacology
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Fibroblasts / cytology
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Fibroblasts / metabolism*
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Gene Knockdown Techniques
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Inflammation / genetics
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Inflammation / metabolism
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Interferon-gamma / genetics
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Interferon-gamma / metabolism*
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Janus Kinase 2 / genetics
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Janus Kinase 2 / metabolism*
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Lentivirus
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Mice
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Microtubule-Associated Proteins / genetics
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Microtubule-Associated Proteins / metabolism*
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Phosphatidylinositol 3-Kinases / genetics
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Phosphatidylinositol 3-Kinases / metabolism
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Phosphoinositide-3 Kinase Inhibitors
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Protein Tyrosine Phosphatase, Non-Receptor Type 11 / genetics
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Protein Tyrosine Phosphatase, Non-Receptor Type 11 / metabolism
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Reactive Oxygen Species / metabolism
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STAT1 Transcription Factor / genetics
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STAT1 Transcription Factor / metabolism*
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Signal Transduction / drug effects
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Signal Transduction / physiology
Substances
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Atg5 protein, mouse
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Atg7 protein, mouse
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Autophagy-Related Protein 5
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Enzyme Inhibitors
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Microtubule-Associated Proteins
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Phosphoinositide-3 Kinase Inhibitors
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Reactive Oxygen Species
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STAT1 Transcription Factor
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Stat1 protein, mouse
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3-methyladenine
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Interferon-gamma
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Jak2 protein, mouse
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Janus Kinase 2
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Protein Tyrosine Phosphatase, Non-Receptor Type 11
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Ptpn11 protein, mouse
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Autophagy-Related Protein 7
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Adenine