Effects of the human immunodeficiency virus type 1 Rev protein on reporter gene and host T-cell gene expression.

The HIV-1 encoded regulatory Rev protein acts to selectively increase the cytoplasmic concentration of incompletely spliced viral mRNAs through interaction with the Rev responsive element (RRE). In addition, the Rev activation domain, believed to be a nuclear export sequence, has been shown to modulate the export of non-RRE containing RNAs (e.g. 5S rRNA, splicesomal U snRNAs). Recent evidence suggests Rev activity depends on interactions with cellular cofactors, leading to speculation that Rev utilizes a cellular RNA and/or a protein export pathway. Rev interactions with cellular cofactors could lead to sequestration of those cofactors from normal cellular activities, suggesting potential Rev effects on cellular gene products and their resultant activity. We have examined the role of Rev in modulating the expression of cellular gene products. Through transient cotransfection assays, we observed a consistent and significant decrease in the levels of luciferase and B-galactosidase activity in the presence of a Rev expressing construct. Cell fractionation studies demonstrated the nuclear retention of the luciferase gene transcripts. Surprisingly, similar effects were observed on constitutively expressed RNAs such as gamma-actin transcripts, and the 18S and 28S rRNAs. These results suggest Rev can disrupt the nuclear export of multiple classes of RNAs.