title: Dual role of alpha-defensin-1 in anti-HIV-1 innate immunity.
abstract: Alpha-defensins are abundant antimicrobial peptides in polymorphonuclear leukocytes and play an important role in innate immunity. We have previously shown that alpha-defensin-1 can inhibit HIV-1 replication following viral entry. Here we examined the molecular mechanism(s) of alpha-defensin-1-mediated HIV-1 inhibition. Alpha-defensin-1 had a direct effect on HIV-1 virions at a low MOI in the absence of serum. The direct effect on HIV-1 virions was abolished by the presence of serum or an increase in virus particles. Studying the kinetics of the HIV life cycle revealed that alpha-defensin-1 inhibited steps following reverse transcription and integration. Analysis of PKC phosphorylation in primary CD4+ T cells in response to alpha-defensin-1 indicated that alpha-defensin-1 inhibited PKC activity. Pretreatment of infected CD4+ T cells with a PKC activator, bryostatin 1, partially reversed alpha-defensin-1-mediated HIV inhibition. Like alpha-defensin-1, the PKC isoform-selective inhibitor Go6976 blocked HIV-1 infection in a dose-dependent manner. Furthermore, kinetic studies and analysis of HIV-1 products indicated that alpha-defensin-1 and Go6976 blocked HIV-1 infection at similar stages in its life cycle, including nuclear import and transcription. Taken together, our studies demonstrate that, in the absence of serum, alpha-defensin-1 may act directly on the virus, but, in the presence of serum, its effects are on the cell, where it inhibits HIV-1 replication. At least 1 of the cellular effects associated with HIV inhibition is interference with PKC signaling in primary CD4+ T cells. Studying the complex function of alpha-defensin-1 in innate immunity against HIV has implications for prevention as well as therapeutics.
authors.affiliation: Department of Medicine, Division of Infectious Diseases, Mount Sinai School of Medicine, New York, New York 10029, USA. Theresa.chang@mssm.edu
authors.forename: Theresa L
authors.initials: TL
authors.lastname: Chang
authors.forename: Jesus
authors.initials: J
authors.lastname: Vargas
authors.forename: Armando
authors.initials: A
authors.lastname: DelPortillo
authors.forename: Mary E
authors.initials: ME
authors.lastname: Klotman
mesh_terms: D000998:Antiviral Agents / Q000378:metabolism*; D015704:CD4 Antigens / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology / Q000821:virology; D002227:Carbazoles / Q000378:metabolism; D002478:Cells, Cultured; D015497:HIV-1 / Q000276:immunology* / Q000502:physiology; D006801:Humans; D007113:Immunity, Innate / Q000502:physiology*; D007211:Indoles / Q000378:metabolism; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000378:metabolism; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism; D019713:Receptors, CCR5 / Q000276:immunology; D019718:Receptors, CXCR4 / Q000276:immunology; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D044967:Serum / Q000276:immunology; D015398:Signal Transduction / Q000502:physiology; D014771:Virion / Q000378:metabolism; D023084:alpha-Defensins / Q000235:genetics / Q000378:metabolism*
chemical_list: D000998:Antiviral Agents; D015704:CD4 Antigens; D002227:Carbazoles; D007211:Indoles; D007527:Isoenzymes; D019713:Receptors, CCR5; D019718:Receptors, CXCR4; D011994:Recombinant Proteins; D023084:alpha-Defensins; C406413:human neutrophil peptide 1; C081021:Go 6976; D011493:Protein Kinase C
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