title: HIV Nef-mediated CD4 down-regulation is adaptor protein complex 2 dependent.
abstract: Nef is a crucial viral protein for HIV to replicate at high titers and in the development of AIDS. One Nef function is down-regulating CD4 from the cell surface, which correlates with Nef-enhanced viral pathogenicity. Nef down-regulates CD4 by linking CD4 to clathrin-coated pits. However, the mechanistic connection between the C-terminal dileucine motif of Nef and the component(s) of the clathrin-coated pits has not been pinpointed. In this report we used two AP-2 complex-specific inhibitors: a dominant negative mutant of Eps15 (Eps15DIII) that binds to the alpha subunit of AP-2 complex and a small interference RNA that is specific for the mu2 subunit of AP-2 complex. We show that both HIV Nef- and SIV Nef-mediated CD4 down-regulations were profoundly blocked by the synergistic effect of Eps15DIII and RNA interference of AP-2 expression. The results demonstrate that HIV/SIV Nef-mediated CD4 down-regulation is AP-2 dependent. We also show that the PMA-induced CD4 down-regulation was blocked by these two inhibitors. Therefore, PMA-induced CD4 down-regulation is also AP-2 dependent. The results demonstrate that, like the tyrosine sorting motif-dependent endocytosis (for which the transferrin receptor and the epidermal growth factor receptor are the two prototypes), dileucine sorting motif-dependent endocytosis of Nef and CD4 are also AP-2 dependent.
authors.affiliation: Skirball Institute of Biomedical Research, New York University School of Medicine, New York, NY 10016, USA. jiny@saturn.med.nyu.edu
authors.forename: Yong-Jiu
authors.initials: YJ
authors.lastname: Jin
authors.forename: Catherine Yi
authors.initials: CY
authors.lastname: Cai
authors.forename: Xiaoping
authors.initials: X
authors.lastname: Zhang
authors.forename: Hui-Tang
authors.initials: HT
authors.lastname: Zhang
authors.forename: John A
authors.initials: JA
authors.lastname: Hirst
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Burakoff
mesh_terms: D033962:Adaptor Protein Complex 2 / Q000502:physiology*; D015704:CD4 Antigens / Q000378:metabolism*; D002460:Cell Line; D002966:Clathrin / Q000502:physiology; D015536:Down-Regulation; D015693:Gene Products, nef / Q000502:physiology*; D006678:HIV / Q000502:physiology*; D006801:Humans; D021122:Protein Subunits; D034622:RNA Interference; D015302:Simian Immunodeficiency Virus / Q000502:physiology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D054311:nef Gene Products, Human Immunodeficiency Virus
chemical_list: D033962:Adaptor Protein Complex 2; D015704:CD4 Antigens; D002966:Clathrin; D015693:Gene Products, nef; D021122:Protein Subunits; D054311:nef Gene Products, Human Immunodeficiency Virus; D013755:Tetradecanoylphorbol Acetate