title: Ku represses the HIV-1 transcription: identification of a putative Ku binding site homologous to the mouse mammary tumor virus NRE1 sequence in the HIV-1 long terminal repeat.
abstract: Ku has been implicated in nuclear processes, including DNA break repair, transcription, V(D)J recombination, and telomere maintenance. Its mode of action involves two distinct mechanisms: one in which a nonspecific binding occurs to DNA ends and a second that involves a specific binding to negative regulatory elements involved in transcription repression. Such elements were identified in mouse mammary tumor virus and human T cell leukemia virus retroviruses. The purpose of this study was to investigate a role for Ku in the regulation of human immunodeficiency virus (HIV)-1 transcription. First, HIV-1 LTR activity was studied in CHO-K1 cells and in CH0-derived xrs-6 cells, which are devoid of Ku80. LTR-driven expression of a reporter gene was significantly increased in xrs-6 cells. This enhancement was suppressed after re-expression of Ku80. Second, transcription of HIV-1 was followed in U1 human cells that were depleted in Ku by using a Ku80 antisense RNA. Ku depletion led to a increase of both HIV-1 mRNA synthesis and viral production compared with the parent cells. These results demonstrate that Ku acts as a transcriptional repressor of HIV-1 expression. Finally, a putative Ku-specific binding site was identified within the negative regulatory region of the HIV-1 long terminal repeat, which may account for this repression of transcription.
authors.affiliation: CNRS UMR8532, Institut Gustave-Roussy, PR2, 39 rue Camille Desmoulins, 94805 Villejuif, France.
authors.forename: Laurence
authors.initials: L
authors.lastname: Jeanson
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Mouscadet
mesh_terms: D016475:3T3 Cells; D000818:Animals; D034961:Antigens, Nuclear; D001483:Base Sequence; D001665:Binding Sites; D016466:CHO Cells; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D015500:Chloramphenicol O-Acetyltransferase / Q000378:metabolism; D006224:Cricetinae; D004265:DNA Helicases; D018076:DNA, Complementary / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000378:metabolism* / Q000502:physiology*; D005822:Genetic Vectors; D016325:HIV Long Terminal Repeat; D015497:HIV-1 / Q000235:genetics*; D006801:Humans; D000072200:Ku Autoantigen; D008324:Mammary Tumor Virus, Mouse / Q000737:chemistry*; D051379:Mice; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000378:metabolism* / Q000502:physiology*; D011485:Protein Binding; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012689:Sequence Homology, Nucleic Acid; D013997:Time Factors; D014158:Transcription, Genetic; D014162:Transfection; D014779:Virus Replication
chemical_list: D034961:Antigens, Nuclear; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; C400564:MNBP-1 protein, human; D009687:Nuclear Proteins; D012333:RNA, Messenger; D015500:Chloramphenicol O-Acetyltransferase; D004265:DNA Helicases; C106893:XRCC5 protein, human; C000606509:Xrcc6 protein, human; C000606510:Xrcc6 protein, mouse; D000072200:Ku Autoantigen