title: Mycobacterium avium infection of mouse macrophages inhibits IFN-gamma Janus kinase-STAT signaling and gene induction by down-regulation of the IFN-gamma receptor.
abstract: Macrophage activation is required to control the growth of intracellular pathogens. Recent data indicate that macrophages become functionally deactivated during mycobacterial infection. We studied macrophage deactivation by examining the expression of a panel of IFN-gamma-inducible genes and activation of Janus Kinase (JAK)-STAT pathway in Mycobacterium avium-infected macrophages. Reduced expression of IFN-gamma-inducible genes-MHC class II gene E beta; MHC class II transactivator; IFN regulatory factor-1; and Mg21, a gene coding for a GTP-binding protein-was observed in M. avium-infected macrophages. Decreased tyrosine phosphorylation and DNA binding activity of STAT1 in M. avium-infected macrophages stimulated with IFN-gamma was observed. Tyrosine phosphorylation of JAK1, JAK2, and IFN-gamma R alpha was also reduced in infected cells. Northern and Western blot analyses showed that a down-regulation of IFN-gamma R alpha- and beta-chain mRNA and protein occurred in M. avium-infected macrophages. The down-regulation of IFN-gamma R and inhibition of STAT1 activation were time dependent and required 4 h of infection for down-regulation of the IFN-gamma R and 8 h for STAT1 inhibition. These findings suggest that M. avium infection inhibits induction of IFN-gamma-inducible genes in mouse macrophages by down-regulating IFN-gamma R, resulting in reduced phosphorylation of IFN-gamma R alpha, JAK1, JAK2, and STAT1.
authors.affiliation: Department of Medical Microbiology and Immunology, Ohio State University, Columbus 43210, USA.
authors.forename: S
authors.initials: S
authors.lastname: Hussain
authors.forename: B S
authors.initials: BS
authors.lastname: Zwilling
authors.forename: W P
authors.initials: WP
authors.lastname: Lafuse
mesh_terms: D000818:Animals; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism / Q000502:physiology; D015536:Down-Regulation / Q000235:genetics / Q000276:immunology*; D005786:Gene Expression Regulation / Q000276:immunology*; D006358:Hot Temperature; D007371:Interferon-gamma / Q000037:antagonists & inhibitors* / Q000502:physiology; D053613:Janus Kinase 1; D053614:Janus Kinase 2; D017737:Macrophages, Peritoneal / Q000201:enzymology / Q000276:immunology / Q000378:metabolism* / Q000382:microbiology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D009162:Mycobacterium avium / Q000254:growth & development / Q000276:immunology*; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism / Q000502:physiology; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D017471:Receptors, Interferon / Q000037:antagonists & inhibitors* / Q000096:biosynthesis / Q000378:metabolism; D050794:STAT1 Transcription Factor; D015398:Signal Transduction / Q000235:genetics / Q000276:immunology*; D015534:Trans-Activators / Q000037:antagonists & inhibitors* / Q000378:metabolism / Q000502:physiology; D015533:Transcriptional Activation; D014443:Tyrosine / Q000037:antagonists & inhibitors / Q000378:metabolism; D000096743:Interferon gamma Receptor
chemical_list: D004268:DNA-Binding Proteins; D007371:Interferon-gamma; D053613:Janus Kinase 1; D053614:Janus Kinase 2; D011505:Protein-Tyrosine Kinases; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D017471:Receptors, Interferon; D050794:STAT1 Transcription Factor; D015534:Trans-Activators; D014443:Tyrosine; D000096743:Interferon gamma Receptor; C494080:Stat1 protein, mouse; C507905:Jak1 protein, mouse; C507926:Jak2 protein, mouse