title: The Nef protein of human immunodeficiency virus is a broad-spectrum modulator of chemokine receptor cell surface levels that acts independently of classical motifs for receptor endocytosis and Galphai signaling.
abstract: Chemokine receptors (CKRs) are important physiological mediators of immune defense, inflammatory responses, and angiogenesis, and they have also been implicated in a number of viral disease processes. Here, we report that the Nef protein of human immunodeficiency virus (HIV) reduces cell surface levels of eight different members of the CC- and CXC-family of CKRs by up to 92%. This broad-range activity required specific elements in HIV(SF2) Nef, including the proline-rich motif P73P76P79P82 as well as the acidic cluster motif E66E67E68E69, and Nef expression induced a marked perinuclear accumulation of CKRs. Surprisingly, receptor mutagenesis demonstrated that the cytoplasmic tail of CCR5 and CXCR4, which is critical for basal and ligand-mediated endocytosis, was completely dispensable for this Nef activity. In contrast, triple-mutation of the highly conserved DRY motif in the second intracellular CKR loop abolished the Nef-mediated down-regulation of CXCR4 independently of this motif's role in CKR binding to heterotrimeric G proteins and signaling via the Galphai subunit. Thus, we identify the lentiviral pathogenicity factor Nef as a unique and broad-range modulator of CKR cell surface levels. Nef uses a mechanism that is distinct from well-established pathways orchestrating CKR metabolism and offers an interesting tool to study the multifaceted biology of CKRs.
authors.affiliation: Department of Virology, University of Heidelberg, D-69120 Heidelberg, Germany.
authors.forename: Nico
authors.initials: N
authors.lastname: Michel
authors.forename: Kerstin
authors.initials: K
authors.lastname: Ganter
authors.forename: Stephanie
authors.initials: S
authors.lastname: Venzke
authors.forename: Julia
authors.initials: J
authors.lastname: Bitzegeio
authors.forename: Oliver T
authors.initials: OT
authors.lastname: Fackler
authors.forename: Oliver T
authors.initials: OT
authors.lastname: Keppler
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D016466:CHO Cells; D002451:Cell Compartmentation; D006224:Cricetinae; D003412:Cricetulus; D003593:Cytoplasm / Q000378:metabolism; D015536:Down-Regulation / Q000235:genetics; D004705:Endocytosis; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000378:metabolism*; D015693:Gene Products, nef / Q000378:metabolism*; D015497:HIV-1 / Q000378:metabolism*; D015498:HIV-2 / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D021381:Protein Transport; D019707:Receptors, Chemokine / Q000737:chemistry / Q000378:metabolism*; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism; D015398:Signal Transduction; D015302:Simian Immunodeficiency Virus / Q000378:metabolism; D054311:nef Gene Products, Human Immunodeficiency Virus
chemical_list: D015693:Gene Products, nef; D019707:Receptors, Chemokine; D043562:Receptors, G-Protein-Coupled; D054311:nef Gene Products, Human Immunodeficiency Virus; C450520:seven-transmembrane G-protein-coupled receptor; D019206:GTP-Binding Protein alpha Subunits, Gi-Go