RESUMO
The Nuclear Factor 90 (NF90) and its isoforms constitute a family of proteins that can interact with double-stranded (ds) RNA, through its dsRNA binding motifs. Due to various potential translational events such as alternative splicing, the human Interleukin enhancer binding factor 3 (ilf3) gene codes for multifunctional proteins that are NF90 and its isoforms, involved in transcription, translation, mRNA export and microRNA biogenesis. These proteins can act as cellular partners affecting viral replication and they are also implicated in host defense. As a result of these numerous functions, these protein isoforms have been given various names over the years, leading to confusion in determining their specific functions. In this review we focus on the role of the human NF90 protein isoforms in DNA and RNA virus replication.
Assuntos
Proteínas do Fator Nuclear 90/metabolismo , Replicação Viral , Genoma Viral , Humanos , Proteínas do Fator Nuclear 90/química , Isoformas de Proteínas/química , Isoformas de Proteínas/metabolismo , RNA Viral/metabolismo , Proteínas Virais/metabolismoRESUMO
Human immunodeficiency virus (HIV)-1 encoded Rev is essential for export from the nucleus to the cytoplasm, of unspliced and singly spliced transcripts coding for structural and nonstructural viral proteins. This process is spatially and temporally coordinated resulting from the interactions between cellular and viral proteins. Here we examined the effects of the sub-cellular localization and dynamics of Rev on the efficiency of nucleocytoplasmic transport of HIV-1 Gag transcripts and virus particle production. Using confocal microscopy and fluorescence recovery after bleaching (FRAP), we report that NF90ctv, a cellular protein involved in Rev function, alters both the sub-cellular localization and dynamics of Rev in vivo, which drastically affects the accumulation of the viral protein p24. The CRM1-dependent nuclear export of Gag mRNA linked to the Rev Response Element (RRE) is dependent on specific domains of the NF90ctv protein. Taken together, our results demonstrate that the appropriate intracellular localization and dynamics of Rev could regulate Gag assembly and HIV-1 replication.
Assuntos
Infecções por HIV/virologia , HIV-1/metabolismo , HIV-1/fisiologia , Proteínas do Fator Nuclear 90/fisiologia , Produtos do Gene rev do Vírus da Imunodeficiência Humana/metabolismo , Células Cultivadas , Recuperação de Fluorescência Após Fotodegradação , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Proteínas de Fluorescência Verde/fisiologia , Infecções por HIV/metabolismo , Células HeLa , Humanos , Proteínas do Fator Nuclear 90/química , Proteínas do Fator Nuclear 90/genética , Proteínas do Fator Nuclear 90/metabolismo , Estrutura Terciária de Proteína/genética , Estrutura Terciária de Proteína/fisiologia , Transporte Proteico/fisiologia , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Proteínas Recombinantes de Fusão/fisiologia , Distribuição Tecidual , Vírion/metabolismo , Vírion/fisiologia , Montagem de Vírus/fisiologia , Replicação Viral/genética , Replicação Viral/fisiologia , Produtos do Gene rev do Vírus da Imunodeficiência Humana/genética , Produtos do Gene rev do Vírus da Imunodeficiência Humana/fisiologiaRESUMO
BACKGROUND: The HIV Rev protein is known to facilitate export of incompletely spliced and unspliced viral transcripts to the cytoplasm, a necessary step in virus life cycle. The Rev-mediated nucleo-cytoplasmic transport of nascent viral transcripts, dependents on interaction of Rev with the RRE RNA structural element present in the target RNAs. The C-terminal variant of dsRNA-binding nuclear protein 90 (NF90ctv) has been shown to markedly attenuate viral replication in stably transduced HIV-1 target cell line. Here we examined a mechanism of interference of viral life cycle involving Rev-NF90ctv interaction. RESULTS: Since Rev:RRE complex formations depend on protein:RNA and protein:protein interactions, we investigated whether the expression of NF90ctv might interfere with Rev-mediated export of RRE-containing transcripts. When HeLa cells expressed both NF90ctv and Rev protein, we observed that NF90ctv inhibited the Rev-mediated RNA transport. In particular, three regions of NF90ctv protein are involved in blocking Rev function. Moreover, interaction of NF90ctv with the RRE RNA resulted in the expression of a reporter protein coding sequences linked to the RRE structure. Moreover, Rev influenced the subcellular localization of NF90ctv, and this process is leptomycin B sensitive. CONCLUSION: The dsRNA binding protein, NF90ctv competes with HIV Rev function at two levels, by competitive protein:protein interaction involving Rev binding to specific domains of NF90ctv, as well as by its binding to the RRE-RNA structure. Our results are consistent with a model of Rev-mediated HIV-1 RNA export that envisions Rev-multimerization, a process interrupted by NF90ctv.