Alterations in HIV-1 Rev transport in response to cell stress

Movement of HIV-I Rev between the nucleus and cytoplasm is essential to its function. While normally nuclear, the protein can be induced to accumulate in the cytoplasm upon inhibition of RNA polymerase I/II. Nuclear accumulat ion of Rev in the presence of these inhibitors was found to be rescued upon addition of leptomycin B, an inhibitor of Rev nuclear export. This finding . in conjunction with kinetic data on nuclear import, indicates that the ef fect of the RNA polymerase inhibitors is due to an inversion of the rates o f nuclear import versus export possibly achieved by increasing the rate of Rev nuclear export. We also examined whether changes in Rev localization co uld be due to a stress response. While neither ultraviolet radiation nor he at shock affected Rev subcellular localization, both oxidative and osmotic shocks induce changes in Rev localization comparable to that observed with the RNA polymerase inhibitors. The ability of certain serine/threonine kina se inhibitors. including CKI/II inhibitors, to cause cytoplasmic accumulati on of Rev suggested that the alteration in Rev distribution could be due to changes in Rev or CRM1 phosphorylation. However, no change in extent of ph osphorylation of either protein is observed upon treatment of cells with an y of the agents tested. indicating involvement of another cellular factor. (C) 2001 Academic Press.