title: Nuclear import of HIV-1 DNA in resting CD4+ T cells requires a cyclosporin A-sensitive pathway.
abstract: Using PCR to monitor early (LTR/LTR (long terminal repeat)) and late (LTR/gag) products of reverse transcription and the formation of HIV-1 LTR circles (indicating nuclear import), we explored the relationship between T cell activation signals and early events in the life cycle of HIV-1 infection. The combination of TCR ligation with either CD28 cross-linking or exogenous IL-2 was required for HIV-1 LTR circle formation in resting CD4+ T cells. Ligation of the TCR or CD28 receptors or addition of IL-2 alone did not induce this process. However, cross-linking the TCR, or IL-2 alone, unlike CD28 ligation, could induce the completion of viral reverse transcription. In contrast, the initiation of HIV-1 reverse transcription could occur in resting CD4+ T cells without any stimulation. Cyclosporin A (CsA), an inhibitor of T cell activation, completely blocked HIV-1 DNA nuclear import in activated CD4+ T cells. The completion of HIV-1 reverse transcription was blocked by CsA in infected CD4+ T cells activated by TCR ligation and IL-2, but not in cells stimulated by TCR and CD28 ligation. The costimulation of CD3 and CD28 mAbs in the presence of IL-2 could not overcome the CsA inhibitory effect on nuclear import of viral DNA. Therefore, the factor(s) involved in a CsA-sensitive pathway plays a critical role in HIV-1 DNA transport from the cytoplasm into the nucleus. Production and movement of HIV-1 DNA in resting CD4+ T cells require two signals: one signal from the TCR, which normally regulates the G0 to G1 transition, induces completion of viral reverse transcription; the other signal through CD28 or an IL-2R-dependent process is sensitive to CsA treatment and regulates viral DNA entry into the nucleus.
authors.affiliation: Washington Regional Primate Research Center, University of Washington, Seattle 98195, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Sun
authors.forename: L M
authors.initials: LM
authors.lastname: Pinchuk
authors.forename: M B
authors.initials: MB
authors.lastname: Agy
authors.forename: E A
authors.initials: EA
authors.lastname: Clark
mesh_terms: D000911:Antibodies, Monoclonal / Q000276:immunology; D001692:Biological Transport / Q000235:genetics / Q000276:immunology; D018106:CD28 Antigens / Q000276:immunology / Q000494:pharmacology; D017252:CD3 Complex / Q000276:immunology / Q000494:pharmacology; D015496:CD4-Positive T-Lymphocytes / Q000187:drug effects / Q000378:metabolism*; D002467:Cell Nucleus / Q000235:genetics* / Q000378:metabolism; D016572:Cyclosporine / Q000494:pharmacology*; D004279:DNA, Viral / Q000378:metabolism*; D015497:HIV-1 / Q000235:genetics*; D006801:Humans; D007376:Interleukin-2 / Q000494:pharmacology; D007399:Interphase / Q000235:genetics / Q000276:immunology*; D008213:Lymphocyte Activation / Q000187:drug effects* / Q000235:genetics
chemical_list: D000911:Antibodies, Monoclonal; D018106:CD28 Antigens; D017252:CD3 Complex; D004279:DNA, Viral; D007376:Interleukin-2; D016572:Cyclosporine