title: Tetraspanins CD9 and CD81 modulate HIV-1-induced membrane fusion.
abstract: Protein organization on the membrane of target cells may modulate HIV-1 transmission. Since the tetraspanin CD81 is associated to CD4, the receptor of HIV-1 envelope protein (Env; gp120/gp41), we have explored the possibility that this molecule may modulate the initial steps of HIV-1 infection. On the other hand, CD81 belongs to the tetraspanin family, which has been described as organizers of protein microdomains on the plasma membrane. Therefore, the role of CD81 and other related tetraspanin, CD9, on the cell-to-cell fusion process mediated by HIV-1 was studied. We found that anti-tetraspanin Abs enhanced the syncytia formation induced by HIV-1 envelope proteins and viral entry in human T lymphoblasts. In addition, anti-CD81 Abs triggered its clustering in patches, where CD4 and CXCR4 were included. Moreover, the knocking down of CD81 and CD9 expression resulted in an increase in syncytia formation and viral entry. Accordingly, overexpression of CD81 and CD9 rendered cells less susceptible to Env-mediated syncytia formation. These data indicate that CD9 and CD81 have an important role in membrane fusion induced by HIV-1 envelope.
authors.affiliation: Servicio de Inmunología, Hospital Universitario de la Princesa, Universidad Autónoma de Madrid, Madrid, Spain.
authors.forename: Mónica
authors.initials: M
authors.lastname: Gordón-Alonso
authors.forename: María
authors.initials: M
authors.lastname: Yañez-Mó
authors.forename: Olga
authors.initials: O
authors.lastname: Barreiro
authors.forename: Susana
authors.initials: S
authors.lastname: Alvarez
authors.forename: M Angeles
authors.initials: MA
authors.lastname: Muñoz-Fernández
authors.forename: Agustín
authors.initials: A
authors.lastname: Valenzuela-Fernández
authors.forename: Francisco
authors.initials: F
authors.lastname: Sánchez-Madrid
mesh_terms: D015703:Antigens, CD / Q000502:physiology*; D002478:Cells, Cultured; D015686:Gene Products, env / Q000502:physiology; D015726:Giant Cells / Q000821:virology; D015699:HIV Envelope Protein gp120 / Q000502:physiology; D015700:HIV Envelope Protein gp41 / Q000502:physiology; D015497:HIV-1 / Q000472:pathogenicity*; D006801:Humans; D008561:Membrane Fusion; D008562:Membrane Glycoproteins / Q000502:physiology*; D013601:T-Lymphocytes / Q000821:virology*; D060225:Tetraspanin 28; D060245:Tetraspanin 29
chemical_list: D015703:Antigens, CD; C554798:CD81 protein, human; C554869:CD9 protein, human; D015686:Gene Products, env; D015699:HIV Envelope Protein gp120; D015700:HIV Envelope Protein gp41; D008562:Membrane Glycoproteins; D060225:Tetraspanin 28; D060245:Tetraspanin 29