title: Hck SH3 domain-dependent abrogation of Nef-induced class 1 MHC down-regulation.
abstract: The ability of specific virally encoded proteins to down-regulate MHC class I molecules may enable infected cells to elude killing by CTL. In the case of HIV-1, Nef appears to be responsible for this effect. Thus, interfering with Nef-induced MHC class I down-regulation would be a strategy for increasing HIV-1-specific CTL activity, particularly towards long-lived T cell populations such as memory T cells that harbor replication-competent virus. Here, using two Nef-expressing human cell model systems, we show that a dominant-negative mutant derived from the Hck protein-tyrosine kinase, composed of the Hck N-terminal region, as well as the SH3 and SH2 domains, was able to inhibit Nef-induced MHC class I molecule down-regulation. This effect was SH3 domain dependent as it was not evident when the cells were transfected with DN-Hck-W93F, an SH3 domain mutant. The inhibitory effect of dominant-negative-Hck (DN-Hck) on Nef-induced class I down-regulation suggests that this Nef-mediated effect requires an interaction between the Nef polyproline site and an SH3-containing cellular protein that is involved in MHC class I molecule turnover. Interfering with the function of the Nef SH3 binding site in this way represents a strategy for assisting the host CTL response to clear HIV-1-infected cells.
authors.affiliation: Centre for Molecular Medicine and Therapeutics, Children's and Women's Health Centre of British Columbia, British Columbia, Canada.
authors.forename: A H
authors.initials: AH
authors.lastname: Chang
authors.forename: M V
authors.initials: MV
authors.lastname: O'Shaughnessy
authors.forename: F R
authors.initials: FR
authors.lastname: Jirik
mesh_terms: D001665:Binding Sites; D015153:Blotting, Western; D015704:CD4 Antigens / Q000378:metabolism; D002460:Cell Line; D015536:Down-Regulation; D005434:Flow Cytometry; D015693:Gene Products, nef / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005799:Genes, Dominant; D015497:HIV-1 / Q000235:genetics / Q000276:immunology*; D015395:Histocompatibility Antigens Class I / Q000276:immunology / Q000378:metabolism*; D006801:Humans; D009154:Mutation / Q000235:genetics; D010455:Peptides / Q000235:genetics / Q000378:metabolism; D011233:Precipitin Tests; D011485:Protein Binding; D011505:Protein-Tyrosine Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D051572:Proto-Oncogene Proteins c-hck; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology; D014162:Transfection; D054311:nef Gene Products, Human Immunodeficiency Virus; D018909:src Homology Domains / Q000235:genetics / Q000502:physiology*
chemical_list: D015704:CD4 Antigens; D015693:Gene Products, nef; D015395:Histocompatibility Antigens Class I; D010455:Peptides; D011518:Proto-Oncogene Proteins; D054311:nef Gene Products, Human Immunodeficiency Virus; C011083:polyproline; D011505:Protein-Tyrosine Kinases; C496631:HCK protein, human; D051572:Proto-Oncogene Proteins c-hck