title: Activation of focal adhesion kinase by Salmonella suppresses autophagy via an Akt/mTOR signaling pathway and promotes bacterial survival in macrophages.
abstract: Autophagy has emerged as an important antimicrobial host defense mechanism that not only orchestrates the systemic immune response, but also functions in a cell autonomous manner to directly eliminate invading pathogens. Pathogenic bacteria such as Salmonella have evolved adaptations to protect themselves from autophagic elimination. Here we show that signaling through the non-receptor tyrosine kinase focal adhesion kinase (FAK) is actively manipulated by the Salmonella SPI-2 system in macrophages to promote intracellular survival. In wild-type macrophages, FAK is recruited to the surface of the Salmonella-containing vacuole (SCV), leading to amplified signaling through the Akt-mTOR axis and inhibition of the autophagic response. In FAK-deficient macrophages, Akt/mTOR signaling is attenuated and autophagic capture of intracellular bacteria is enhanced, resulting in reduced bacterial survival. We further demonstrate that enhanced autophagy in FAK(-/-) macrophages requires the activity of Atg5 and ULK1 in a process that is distinct from LC3-assisted phagocytosis (LAP). In vivo, selective knockout of FAK in macrophages resulted in more rapid clearance of bacteria from tissues after oral infection with S. typhimurium. Clearance was correlated with reduced infiltration of inflammatory cell types into infected tissues and reduced tissue damage. Together, these data demonstrate that FAK is specifically targeted by S. typhimurium as a novel means of suppressing autophagy in macrophages, thereby enhancing their intracellular survival.
authors.affiliation: Department of Cell Biology, University of Virginia Health System, Charlottesville, Virginia, United States of America.
authors.forename: Katherine A
authors.initials: KA
authors.lastname: Owen
authors.affiliation: Department of Cell Biology, University of Virginia Health System, Charlottesville, Virginia, United States of America.
authors.forename: Corey B
authors.initials: CB
authors.lastname: Meyer
authors.affiliation: Department of Microbiology, University of Virginia Health System, Charlottesville, Virginia, United States of America.
authors.forename: Amy H
authors.initials: AH
authors.lastname: Bouton
authors.affiliation: Department of Cell Biology, University of Virginia Health System, Charlottesville, Virginia, United States of America; Department of Microbiology, University of Virginia Health System, Charlottesville, Virginia, United States of America.
authors.forename: James E
authors.initials: JE
authors.lastname: Casanova
mesh_terms: D000818:Animals; D001343:Autophagy; D000071187:Autophagy-Related Protein 5; D000071189:Autophagy-Related Protein-1 Homolog; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D002478:Cells, Cultured; D004789:Enzyme Activation; D004926:Escherichia coli / Q000276:immunology / Q000378:metabolism / Q000472:pathogenicity; D051417:Focal Adhesion Kinase 1 / Q000235:genetics / Q000378:metabolism*; D017737:Macrophages, Peritoneal / Q000166:cytology / Q000276:immunology* / Q000378:metabolism / Q000382:microbiology; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D018345:Mice, Knockout; D050296:Microbial Viability; D008869:Microtubule-Associated Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D010587:Phagocytosis; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D034622:RNA Interference; D012480:Salmonella Infections / Q000276:immunology / Q000378:metabolism / Q000382:microbiology; D012486:Salmonella typhimurium / Q000276:immunology* / Q000378:metabolism / Q000472:pathogenicity; D015398:Signal Transduction; D013047:Specific Pathogen-Free Organisms; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism*; D051197:Toll-Like Receptor 4 / Q000235:genetics / Q000378:metabolism
chemical_list: C495773:Atg5 protein, mouse; D000071187:Autophagy-Related Protein 5; D001426:Bacterial Proteins; D008565:Membrane Proteins; D008869:Microtubule-Associated Proteins; C440638:SPI-2 protein, Salmonella; C493487:Tlr4 protein, mouse; D051197:Toll-Like Receptor 4; C546843:mTOR protein, mouse; D051417:Focal Adhesion Kinase 1; C496051:Ptk2 protein, mouse; C514862:Akt1 protein, mouse; D000071189:Autophagy-Related Protein-1 Homolog; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D058570:TOR Serine-Threonine Kinases; C112444:Ulk1 protein, mouse