Rev Protein of Human Immunodeficiency Virus Type 1 Facilitates Translation of rev-dependent Viral Messenger RNAs
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Human immunodeficiency virus type 1 (HIV1) Rev has been reported to act by inducing the nucleocytoplasmic transport of unspliced and singly spliced RNAs that encode viral structural proteins. However, our initial experiments indicated the cytoplasmic expression of intron-containing mRNAs in Rev<SUP>-</SUP>cells . To determine whether or not the post-transcriptional induction of gene expression by Rev extends to the level of increasing the efficiency of translation, Rev<SUP>+</SUP> and Rev<SUP>-</SUP>cells were morphologically examined by means of <I>in situ</I> hybridization and immunofluorescence assays. Hybridization to an intron-specific probe revealed that the transfection of HeLa cells with a <I>rev</I>-defective HIV-1 expression plasmid caused the export of overexpressed, unspliced <I>gag</I> mRNAs, possibly through a default process of nuclear retention. However, subsequent immunofluorescence assaying demonstrated that mRNA exported by Rev, but not mRNA directed through the default process, was translated into the corresponding protein. The findings were extended to a group of singly spliced viral mRNAs that produce Env in the following biochemical analyses. These findings suggest that Rev is directly or indirectly involved in the translational regulation of HIV-1 structural gene mRNAs. We discuss the possibility that Rev could cause the intron-containing transcripts to follow the appropriate pathway to reach the translational machinery.
- ACTA HISTOCHEMICA ET CYTOCHEMICA
ACTA HISTOCHEMICA ET CYTOCHEMICA 30(5), 617-621, 1997-10-01
JAPAN SOCIETY OF HISTOCHEMISTRY AND CYTOCHEMISTRY