Regulation of HIV-1 env mRNA translation by Rev protein.

We have examined the effect of Rev on the regulation of the expression of RRE containing mRNAs when they were synthesised in the nucleus or directly in the cytoplasm. In the nuclear expression system, Rev enhanced env mRNA transport by about 1.6-fold, while translation of this mRNA was increased more than a 100-fold. These findings indicate that the target of Rev activity is located mainly at the translational level. Synthesis of Env using a recombinant vaccinia virus system, which synthesised env mRNA directly in the cytoplasm, is also enhanced by Rev. Finally, RRE functioning was examined using a luciferase mRNA bearing this element. Rev stimulated the synthesis of Luciferase both when the luc mRNA was made in the nucleus or in cytoplasm. Our results indicate that the effect of Rev on env mRNA transport is low compared with the enhancement of translation of this mRNA.