Nuclear Factor 90, a cellular dsRNA binding protein inhibits the HIV Rev-export function.
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.


CONCLUSIONS
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.
Urcuqui-Inchima
Silvio
S
Grupo de Inmunovirología, Corporación Biogénesis, Universidad de Antioquia, Medellín, Colombia. silviourcuqui@gmail.com
Castaño
Maria Eugenia
ME
Hernandez-Verdun
Danièle
D
St-Laurent
Georges
G
Kumar
Ajit
A
D021581:Active Transport, Cell Nucleus; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D005786:Gene Expression Regulation; D015694:Gene Products, rev / Q000037:antagonists & inhibitors* / Q000378:metabolism; D017930:Genes, Reporter; D015497:HIV-1 / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D050779:Nuclear Factor 90 Proteins / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D025941:Protein Interaction Mapping; D017434:Protein Structure, Tertiary; D012367:RNA, Viral / Q000378:metabolism*; D014779:Virus Replication / Q000502:physiology; D054321:rev Gene Products, Human Immunodeficiency Virus
D015694:Gene Products, rev; C429643:ILF3 protein, human; D050779:Nuclear Factor 90 Proteins; D012367:RNA, Viral; D054321:rev Gene Products, Human Immunodeficiency Virus; C514860:rev protein, Human Immunodeficiency Virus-1