title: Inhibition of CD3/CD28-mediated activation of the MEK/ERK signaling pathway represses replication of X4 but not R5 human immunodeficiency virus type 1 in peripheral blood CD4(+) T lymphocytes.
abstract: Binding of human immunodeficiency virus type 1 (HIV-1) to CD4 receptors induces multiple cellular signaling pathways, including the MEK/ERK cascade. While the interaction of X4 HIV-1 with CXCR4 does not seem to activate this pathway, viruses using CCR5 for entry efficiently activate MEK/ERK kinases (W. Popik, J. E. Hesselgesser, and P. M. Pitha, J. Virol. 72:6406-6413, 1998; W. Popik and P. M. Pitha, Virology 252:210-217, 1998). Since the importance of MEK/ERK in the initial steps of viral replication is poorly understood, we have examined the role of MEK/ERK signaling in the CD3- and CD28 (CD3/CD28)-mediated activation of HIV-1 replication in resting peripheral blood CD4(+) T lymphocytes infected with X4 or R5 HIV-1. We have found that the MEK/ERK inhibitor U0126 selectively inhibited CD3/CD28-stimulated replication of X4 HIV-1, while it did not affect the replication of R5 HIV-1. Inhibition of the CD3/CD28-stimulated MEK/ERK pathway did not affect the formation of the early proviral transcripts in cells infected with either X4 or R5 HIV-1, indicating that virus reverse transcription is not affected in the absence of MEK/ERK signaling. In contrast, the levels of nuclear provirus in cells infected with X4 HIV-1, detected by the formation of circular proviral DNA, was significantly lower in cells stimulated in the presence of MEK/ERK inhibitor than in the absence of the inhibitor. However, in cells infected with R5 HIV-1, the inhibition of the MEK/ERK pathway did not affect nuclear localization of the proviral DNA. These data suggest that the nuclear import of X4, but not R5, HIV-1 is dependent on a CD3/CD28-stimulated MEK/ERK pathway.
authors.affiliation: Oncology Center, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21231, USA. wpopik@jhmi.edu
authors.forename: W
authors.initials: W
authors.lastname: Popik
authors.forename: P M
authors.initials: PM
authors.lastname: Pitha
mesh_terms: D001692:Biological Transport; D002070:Butadienes / Q000494:pharmacology; D018106:CD28 Antigens / Q000378:metabolism*; D017252:CD3 Complex / Q000378:metabolism*; D015704:CD4 Antigens / Q000378:metabolism; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology / Q000821:virology*; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D004279:DNA, Viral / Q000378:metabolism; D015536:Down-Regulation; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015497:HIV-1 / Q000187:drug effects / Q000302:isolation & purification / Q000502:physiology*; D006801:Humans; D020935:MAP Kinase Signaling System; D020929:Mitogen-Activated Protein Kinase Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009570:Nitriles / Q000494:pharmacology; D011533:Proviruses / Q000235:genetics; D019718:Receptors, CXCR4 / Q000378:metabolism; D014158:Transcription, Genetic; D016662:Virus Integration; D014779:Virus Replication / Q000187:drug effects*
chemical_list: D002070:Butadienes; D018106:CD28 Antigens; D017252:CD3 Complex; D015704:CD4 Antigens; D004279:DNA, Viral; D004791:Enzyme Inhibitors; D009570:Nitriles; D019718:Receptors, CXCR4; C113580:U 0126; D020929:Mitogen-Activated Protein Kinase Kinases