title: Disparate regulation of LPS-induced MAPK signaling and IL-12p40 expression between different myeloid cell types with and without HIV infection.
abstract: Studies from our laboratory and those of others have implicated lipopolysaccharide (LPS)-induced MAPK signaling as an important pathway in the regulation of cytokine expression. In this article, the regulation of IL-12 expression in two different human myeloid cell populations was evaluated. In primary monocytes, the inhibition of p38 enhanced IL-12 production, whereas it downregulated IL-12 production in THP-1 cells. The role of MAPK signaling in transcription factor binding to the IL-12p40 promoter was subsequently determined. In primary monocytes, ERK and p38 inhibition increased binding of AP-1 and Sp1, respectively, to the IL-12p40 promoter, while JNK inhibition increased NF-kappaB, AP-1, and Sp1 binding. In THP-1 cells, p38, ERK, and JNK inhibition increased NF-kappaB and Sp1 binding to the IL-12p40 promoter, while inhibiting AP-1 binding. In monocytes, mutations in the NF-kappaB, AP-1, Sp1, or Ets-2 binding sites resulted in complete inhibition of LPS-stimulated IL-12p40 promoter activity using a luciferase-based assay. In contrast, promoter activity was abrogated in THP-1 cells only when the Sp1 or Ets-2 binding sites were mutated. Transcription factor binding to the IL-12p40 promoter following in-vitro HIV infection demonstrated several differences between monocytes and THP-1 cells. Infection with HIV produced an increase in NF-kappaB, AP-1, and Sp1 binding in primary monocytes. In contrast, binding of Ets-2 was dramatically impaired following HIV infection of monocytes, but was unaffected in THP-1 cells. These data clearly show that although LPS induces IL-12p40 expression in primary monocytes and THP-1 cells, the signaling pathways involved and the effect of HIV infection differ and can have disparate effects in these two cell types.
authors.affiliation: Ottawa Hospital Research Institute, Ottawa, Ontario, Canada.
authors.forename: Jonathan G
authors.initials: JG
authors.lastname: Boucher
authors.forename: Kelley A
authors.initials: KA
authors.lastname: Parato
authors.forename: Fiona
authors.initials: F
authors.lastname: Frappier
authors.forename: Peter
authors.initials: P
authors.lastname: Fairman
authors.forename: Aurelia
authors.initials: A
authors.lastname: Busca
authors.forename: Mansi
authors.initials: M
authors.lastname: Saxena
authors.forename: Maria A
authors.initials: MA
authors.lastname: Blahoianu
authors.forename: Wei
authors.initials: W
authors.lastname: Ma
authors.forename: Niranjala
authors.initials: N
authors.lastname: Gajanayaka
authors.forename: Robin J
authors.initials: RJ
authors.lastname: Parks
authors.forename: Ashok
authors.initials: A
authors.lastname: Kumar
authors.forename: Jonathan B
authors.initials: JB
authors.lastname: Angel
mesh_terms: D002460:Cell Line; D002478:Cells, Cultured; D004247:DNA / Q000378:metabolism; D015658:HIV Infections / Q000276:immunology*; D006801:Humans; D053762:Interleukin-12 Subunit p40 / Q000096:biosynthesis*; D008070:Lipopolysaccharides / Q000276:immunology*; D020935:MAP Kinase Signaling System; D022423:Myeloid Cells / Q000276:immunology*; D016328:NF-kappa B / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D050787:Proto-Oncogene Protein c-ets-2 / Q000378:metabolism; D015398:Signal Transduction; D016329:Sp1 Transcription Factor / Q000378:metabolism; D018808:Transcription Factor AP-1 / Q000378:metabolism
chemical_list: D053762:Interleukin-12 Subunit p40; D008070:Lipopolysaccharides; D016328:NF-kappa B; D050787:Proto-Oncogene Protein c-ets-2; D016329:Sp1 Transcription Factor; D018808:Transcription Factor AP-1; D004247:DNA