title: Role of protein kinase C-alpha in the control of infection by intracellular pathogens in macrophages.
abstract: The protein kinase C (PKC) family regulates macrophage function involved in host defense against infection. In this study, we investigated the role of macrophage PKC-alpha in the uptake and subsequent fate of Leishmania donovani promastigotes and Legionella pneumophila infections. To this end, we used clones of the murine macrophage cell line RAW 264.7 overexpressing a dominant-negative (DN) mutant of PKC-alpha. While phagocytosis of L. donovani promastigotes was not affected by DN PKC-alpha overexpression, their intracellular survival was enhanced by 10- to 20-fold at 48 h postinfection. Intracellular survival of a L. donovani mutant defective in lipophosphoglycan repeating units synthesis, which normally is rapidly degraded in phagolysosomes, was enhanced by 100-fold at 48 h postinfection. However, IFN-gamma-induced leishmanicidal activity was not affected by DN PKC-alpha overexpression. Similar to macrophages from genetically resistant C57BL/6 mice, control RAW 264.7 cells were not permissive for the intracellular replication of Legionella pneumophila. In contrast, DN PKC-alpha-overexpressing RAW 264.7 clones were phenotypically similar to macrophages from genetically susceptible A/J mice, as they allowed intracellular replication of L. pneumophila. Permissiveness to L. pneumophila was not the consequence of a general defect in the microbicidal capacities because killing of a temperature-sensitive mutant of Pseudomonas aeruginosa was normal in DN PKC-alpha-overexpressing RAW 264.7 clones. Collectively, these results support a role for PKC-alpha in the regulation of innate macrophage functions involved in the control of infection by intracellular parasites.
authors.affiliation: INRS-Institut Armand-Frappier, Université du Québec, Laval, Canada.
authors.forename: A
authors.initials: A
authors.lastname: St-Denis
authors.forename: V
authors.initials: V
authors.lastname: Caouras
authors.forename: F
authors.initials: F
authors.lastname: Gervais
authors.forename: A
authors.initials: A
authors.lastname: Descoteaux
mesh_terms: D000818:Animals; D002460:Cell Line; D005799:Genes, Dominant; D007371:Interferon-gamma / Q000494:pharmacology; D007424:Intracellular Fluid / Q000201:enzymology* / Q000276:immunology* / Q000382:microbiology / Q000469:parasitology; D007527:Isoenzymes / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D016952:Legionella pneumophila / Q000254:growth & development / Q000276:immunology*; D007893:Leishmania donovani / Q000254:growth & development / Q000276:immunology*; D017737:Macrophages, Peritoneal / Q000201:enzymology* / Q000276:immunology* / Q000382:microbiology / Q000469:parasitology; D051379:Mice; D008805:Mice, Inbred A; D008810:Mice, Inbred C57BL; D009154:Mutation; D009569:Nitric Oxide / Q000096:biosynthesis; D011493:Protein Kinase C / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D051571:Protein Kinase C-alpha; D013481:Superoxides / Q000378:metabolism
chemical_list: D007527:Isoenzymes; D013481:Superoxides; D009569:Nitric Oxide; D007371:Interferon-gamma; C496630:Prkca protein, mouse; D011493:Protein Kinase C; D051571:Protein Kinase C-alpha