title: Heat shock protein 40 is necessary for human immunodeficiency virus-1 Nef-mediated enhancement of viral gene expression and replication.
abstract: The human immunodeficiency virus-1 (HIV-1) Nef protein, originally identified as a negative factor, has now emerged as one of the most important viral proteins necessary for viral pathogenesis and disease progression. Nef has been also implicated in viral infectivity and replication, however, the molecular mechanism of Nef-induced viral gene expression and replication is not clearly understood. Although involvement of heat shock proteins in viral pathogenesis has been reported earlier, a clear understanding of their role remains to be elucidated. Here we report for the first time that Nef not only interacts with heat shock protein 40 (Hsp40) but it also induces the expression of Hsp40 in HIV-1-infected cells. The interaction between Nef and Hsp40 is important for increased Hsp40 translocation into the nucleus of infected cells, which seems to facilitate viral gene expression by becoming part of the cyclin-dependent kinase 9-associated transcription complex regulating long terminal repeat-mediated gene expression. The finding is consistent with the failure of the nef-deleted virus to induce Hsp40, resulting in reduced virus production. Our data further shows that, whereas, Hsp40 overexpression induces viral gene expression, silencing of Hsp40 reduces the gene expression in a Nef-dependent manner. Thus our results clearly indicate that Hsp40 is crucial for Nef-mediated enhancement of viral gene expression and replication.
authors.affiliation: National Centre for Cell Science, Ganeshkhind, Pune-411007, India.
authors.forename: Manish
authors.initials: M
authors.lastname: Kumar
authors.forename: Debashis
authors.initials: D
authors.lastname: Mitra
mesh_terms: D000595:Amino Acid Sequence; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D042863:Cyclin-Dependent Kinase 9 / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D015536:Down-Regulation; D004926:Escherichia coli / Q000378:metabolism; D015967:Gene Expression Regulation, Viral; D015693:Gene Products, nef / Q000378:metabolism / Q000502:physiology*; D020868:Gene Silencing; D005982:Glutathione Transferase / Q000378:metabolism; D016325:HIV Long Terminal Repeat; D015497:HIV-1 / Q000378:metabolism*; D050956:HSP40 Heat-Shock Proteins / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D047468:Immunoprecipitation; D008156:Luciferases / Q000378:metabolism; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D034741:RNA, Small Interfering / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D013997:Time Factors; D014162:Transfection; D020798:Two-Hybrid System Techniques; D015854:Up-Regulation; D014779:Virus Replication; D001616:beta-Galactosidase / Q000378:metabolism; D054311:nef Gene Products, Human Immunodeficiency Virus
chemical_list: D015693:Gene Products, nef; D050956:HSP40 Heat-Shock Proteins; D034741:RNA, Small Interfering; D011994:Recombinant Proteins; D054311:nef Gene Products, Human Immunodeficiency Virus; D008156:Luciferases; D005982:Glutathione Transferase; D042863:Cyclin-Dependent Kinase 9; D001616:beta-Galactosidase