title: Pertussis toxin B-oligomer suppresses IL-6 induced HIV-1 and chemokine expression in chronically infected U1 cells via inhibition of activator protein 1.
abstract: Pertussis toxin B-oligomer (PTX-B) inhibits HIV replication in T lymphocytes and monocyte-derived macrophages by interfering with multiple steps of the HIV life cycle. PTX-B prevents CCR5-dependent (R5) virus entry in a noncompetitive manner, and it also exerts suppressive effects on both R5- and CXCR4-dependent HIV expression at a less-characterized postentry level. We demonstrate in this study that PTX-B profoundly inhibits HIV expression in chronically infected promonocytic U1 cells stimulated with several cytokines and, particularly, the IL-6-mediated effect, a cytokine that triggers viral production in these cells independently of NF-kappaB activation. From U1 cells we have subcloned a cell line, named U1-CR1, with increased responsiveness to IL-6. In these cells, PTX-B neither down-regulated the IL-6R nor prevented IL-6 induced signaling in terms of STAT3 phosphorylation and DNA binding. In contrast, PTX-B inhibited AP-1 binding to target DNA and modified its composition with a proportional increases in FosB, Fra2, and ATF2. PTX-B inhibited IL-6-induced HIV-1 long-terminal repeat-driven transcription from A, C, E, and F viral subtypes, which contain functional AP-1 binding sites, but failed to inhibit transcription from subtypes B and D LTR devoid of these sites. In addition, PTX-B inhibited the secretion of IL-6-induced, AP-1-dependent genes, including urokinase-type plasminogen activator, CXCL8/IL-8, and CCL2/monocyte chemotactic protein-1. Thus, PTX-B suppression of IL-6 induced expression of HIV and cellular genes in chronically infected promonocytic cells is strongly correlated to inhibition of AP-1.
authors.affiliation: AIDS Immunopathogenesis Unit, San Raffaele Scientific Institute, Milan, Italy.
authors.forename: Chiara
authors.initials: C
authors.lastname: Rizzi
authors.forename: Massimo P
authors.initials: MP
authors.lastname: Crippa
authors.forename: Rienk E
authors.initials: RE
authors.lastname: Jeeninga
authors.forename: Ben
authors.initials: B
authors.lastname: Berkhout
authors.forename: Francesco
authors.initials: F
authors.lastname: Blasi
authors.forename: Guido
authors.initials: G
authors.lastname: Poli
authors.forename: Massimo
authors.initials: M
authors.lastname: Alfano
mesh_terms: D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D002460:Cell Line; D018925:Chemokines / Q000096:biosynthesis*; D002999:Clone Cells; D004247:DNA / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression / Q000187:drug effects; D016325:HIV Long Terminal Repeat / Q000187:drug effects; D015497:HIV-1 / Q000187:drug effects* / Q000235:genetics / Q000502:physiology; D006801:Humans; D015850:Interleukin-6 / Q000494:pharmacology*; D037342:Pertussis Toxin / Q000737:chemistry / Q000494:pharmacology*; D019947:Receptors, Interleukin-6 / Q000378:metabolism; D050796:STAT3 Transcription Factor / Q000378:metabolism; D018808:Transcription Factor AP-1 / Q000037:antagonists & inhibitors*; D014568:Urokinase-Type Plasminogen Activator / Q000235:genetics; D014779:Virus Replication / Q000187:drug effects
chemical_list: D018925:Chemokines; D015850:Interleukin-6; D019947:Receptors, Interleukin-6; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; D018808:Transcription Factor AP-1; D004247:DNA; D037342:Pertussis Toxin; D014568:Urokinase-Type Plasminogen Activator