title: Polarized expression of the membrane ASP protein derived from HIV-1 antisense transcription in T cells.
abstract: BACKGROUND
  Retroviral gene expression generally depends on a full-length transcript that initiates in the 5' LTR, which is either left unspliced or alternatively spliced. We and others have demonstrated the existence of antisense transcription initiating in the 3' LTR in human lymphotropic retroviruses, including HTLV-1, HTLV-2, and HIV-1. Such transcripts have been postulated to encode antisense proteins important for the establishment of viral infections. The antisense strand of the HIV-1 proviral DNA contains an ORF termed asp, coding for a highly hydrophobic protein. However, although anti-ASP antibodies have been described to be present in HIV-1-infected patients, its in vivo expression requires further support. The objective of this present study was to clearly demonstrate that ASP is effectively expressed in infected T cells and to provide a better characterization of its subcellular localization.
  
  
  RESULTS
  We first investigated the subcellular localization of ASP by transfecting Jurkat T cells with vectors expressing ASP tagged with the Flag epitope to its N-terminus. Using immunofluorescence microscopy, we found that ASP localized to the plasma membrane in transfected Jurkat T cells, but with different staining patterns. In addition to an entire distribution to the plasma membrane, ASP showed an asymmetric localization and could also be detected in membrane connections between two cells. We then infected Jurkat T cells with NL4.3 virus coding for ASP tagged with the Flag epitope at its C-terminal end. By this approach, we were capable of showing that ASP is effectively expressed from the HIV-1 3' LTR in infected T cells, with an asymmetric localization of the viral protein at the plasma membrane.
  
  
  CONCLUSIONS
  These results demonstrate for the first time that ASP can be detected when expressed from full-length HIV-1 proviral DNA and that its localization is consistent with Jurkat T cells overexpressing ASP.
authors.affiliation: Université Montpellier 1, Centre d'Études d'Agents Pathogènes et Biotechnologies pour la Santé, Montpellier, France.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Clerc
authors.forename: Sylvain
authors.initials: S
authors.lastname: Laverdure
authors.forename: Cynthia
authors.initials: C
authors.lastname: Torresilla
authors.forename: Sébastien
authors.initials: S
authors.lastname: Landry
authors.forename: Sophie
authors.initials: S
authors.lastname: Borel
authors.forename: Amandine
authors.initials: A
authors.lastname: Vargas
authors.forename: Charlotte
authors.initials: C
authors.lastname: Arpin-André
authors.forename: Bernard
authors.initials: B
authors.lastname: Gay
authors.forename: Laurence
authors.initials: L
authors.lastname: Briant
authors.forename: Antoine
authors.initials: A
authors.lastname: Gross
authors.forename: Benoît
authors.initials: B
authors.lastname: Barbeau
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Mesnard
mesh_terms: D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism / Q000821:virology*; D015967:Gene Expression Regulation, Viral; D015658:HIV Infections / Q000378:metabolism / Q000821:virology*; D015497:HIV-1 / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D009154:Mutation; D021381:Protein Transport; D016372:RNA, Antisense / Q000235:genetics* / Q000378:metabolism; D012367:RNA, Viral / Q000235:genetics* / Q000378:metabolism; D013601:T-Lymphocytes / Q000378:metabolism / Q000821:virology*; D014764:Viral Proteins / Q000235:genetics* / Q000378:metabolism
chemical_list: D016372:RNA, Antisense; D012367:RNA, Viral; D014764:Viral Proteins