Abstract
HIV-1-infected cells are partially resistant to anti-HIV cytotoxic T lymphocytes (CTLs) due to the effects of the HIV Nef protein on antigen presentation by major histocompatibility complex class I (MHC-I), and evidence has been accumulating that this function of Nef is important in vivo. HIV Nef disrupts the normal expression of MHC-I by stabilizing a protein-protein interaction between the clathrin adaptor protein AP-1 and the MHC-I cytoplasmic tail. There is also evidence that Nef activates a phosphatidylinositol 3 kinase (PI3K)-dependent GTPase, ADP ribosylation factor 6 (ARF-6), to stimulate MHC-I internalization. However, the relative importance of these two pathways is unclear. Here we report that a GTPase required for AP-1 activity (ARF-1) was needed for Nef to disrupt MHC-I surface levels, whereas no significant requirement for ARF-6 was observed in Nef-expressing T cell lines and in HIV-infected primary T cells. An ARF-1 inhibitor blocked the ability of Nef to recruit AP-1 to the MHC-I cytoplasmic tail, and a dominant active ARF-1 mutant stabilized the Nef-MHC-I-AP-1 complex. These data support a model in which Nef and ARF-1 stabilize an interaction between MHC-I and AP-1 to disrupt the presentation of HIV-1 epitopes to CTLs.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
MeSH terms
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ADP-Ribosylation Factor 1 / antagonists & inhibitors
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ADP-Ribosylation Factor 1 / genetics
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ADP-Ribosylation Factor 1 / metabolism*
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ADP-Ribosylation Factor 6
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ADP-Ribosylation Factors / antagonists & inhibitors
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ADP-Ribosylation Factors / genetics
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ADP-Ribosylation Factors / metabolism*
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Antigen Presentation
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Blotting, Western
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Cells, Cultured
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Cytoplasm / metabolism
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Enzyme-Linked Immunosorbent Assay
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Fluorescent Antibody Technique
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Genetic Vectors
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HIV Infections / genetics
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HIV Infections / immunology
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HIV Infections / virology*
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HIV-1 / genetics
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HIV-1 / pathogenicity
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HLA-A2 Antigen / genetics
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HLA-A2 Antigen / metabolism*
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Humans
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Immunoprecipitation
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Protein Binding
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Protein Transport
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T-Lymphocytes / immunology
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T-Lymphocytes / metabolism*
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T-Lymphocytes / virology*
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Transcription Factor AP-1 / genetics
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Transcription Factor AP-1 / metabolism*
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nef Gene Products, Human Immunodeficiency Virus / genetics
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nef Gene Products, Human Immunodeficiency Virus / metabolism
Substances
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ADP-Ribosylation Factor 6
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HLA-A2 Antigen
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Transcription Factor AP-1
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nef Gene Products, Human Immunodeficiency Virus
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ADP-Ribosylation Factor 1
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ADP-Ribosylation Factors
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ARF6 protein, human