title: Leishmania inhibits STAT1-mediated IFN-gamma signaling in macrophages: increased tyrosine phosphorylation of dominant negative STAT1beta by Leishmania mexicana.
abstract: Previous studies have demonstrated that Leishmania donovani attenuates STAT1-mediated signaling in macrophages; however it is not clear whether other species of Leishmania, which cause cutaneous disease, also interfere with macrophage IFN-gamma signaling. Therefore, we determined the effect of Leishmania major and Leishmania mexicana infection on STAT1-mediated IFN-gamma signaling pathway in J774A.1 and RAW264.7 macrophages. We found that both L. major and L. mexicana suppressed IFNgammaRalpha (alpha subunit of interferon gamma receptor) and IFN-gammaRbeta (beta subunit of interferon gamma receptor) expression, reduced levels of total Jak1 and Jak2, and down-regulated IFN-gamma-induced Jak1, Jak2 and STAT1 activation. The effect of L. mexicana infection on Jak1, Jak2 and STAT1 activation was more profound when compared with L. major. Although tyrosine phosphorylation of STAT1alpha was decreased in IFN-gamma stimulated macrophages infected with L. major or L. mexicana, those infected with L. mexicana showed a significant increase in phosphorylation of the dominant negative STAT1beta. These findings indicate that L. major and L. mexicana attenuate STAT1-mediated IFN-gamma signaling in macrophages. Furthermore, they also demonstrate that L. mexicana preferentially enhances tyrosine phosphorylation of dominant negative STAT1beta, which may be one of the several survival mechanisms used by this parasite to evade the host defense mechanisms.
authors.affiliation: Department of Microbiology, The Ohio State University, 484 West 12th Avenue, Columbus, OH 43210, USA.
authors.forename: Neeti
authors.initials: N
authors.lastname: Bhardwaj
authors.forename: Lucia E
authors.initials: LE
authors.lastname: Rosas
authors.forename: William P
authors.initials: WP
authors.lastname: Lafuse
authors.forename: Abhay R
authors.initials: AR
authors.lastname: Satoskar
mesh_terms: D000818:Animals; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000276:immunology* / Q000378:metabolism; D006801:Humans; D007371:Interferon-gamma / Q000096:biosynthesis*; D053613:Janus Kinase 1; D053614:Janus Kinase 2; D018320:Leishmania major / Q000276:immunology*; D007894:Leishmania mexicana / Q000276:immunology*; D008264:Macrophages / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D050794:STAT1 Transcription Factor; D015398:Signal Transduction / Q000276:immunology; D015534:Trans-Activators / Q000276:immunology* / Q000378:metabolism; D014443:Tyrosine / Q000378:metabolism*; D015854:Up-Regulation / Q000276:immunology
chemical_list: D004268:DNA-Binding Proteins; D011518:Proto-Oncogene Proteins; D050794:STAT1 Transcription Factor; C494079:STAT1 protein, human; C494080:Stat1 protein, mouse; D015534:Trans-Activators; D014443:Tyrosine; D007371:Interferon-gamma; D011505:Protein-Tyrosine Kinases; C507904:JAK1 protein, human; C507924:JAK2 protein, human; C507905:Jak1 protein, mouse; C507926:Jak2 protein, mouse; D053613:Janus Kinase 1; D053614:Janus Kinase 2