Rev-dependent association of the intron-containing HIV-1 gag mRNA with the nuclear actin bundles and the inhibition of its nucleocytoplasmic transport by latrunculin-B - PubMed (original) (raw)

Rev-dependent association of the intron-containing HIV-1 gag mRNA with the nuclear actin bundles and the inhibition of its nucleocytoplasmic transport by latrunculin-B

T Kimura et al. Genes Cells. 2000 Apr.

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Abstract

Background: A hallmark of HIV-1 gene expression is that unspliced genomic RNA, which also acts as mRNA for the expression of Gag/Pol, is exported to the cytoplasm. Rev directs this transport through the nuclear export signal (NES).

Results: Fluorescence in situ hybridization and immunocytochemistry demonstrated that gag mRNA, Rev, and its NES receptor, CRM1, and RanGTPase formed nuclear tracks which were congruent with underlying beta-actin bundles. Actin bundle formation was confirmed electron-microscopically. These bundles were observed upon Rev-containing gag RNP formation. The loss of bundles was associated with the nuclear retention of gag mRNA. Reverse transcription-polymerase chain reaction analysis of both cytoplasmic and nuclear gag mRNAs demonstrated that disruption of nuclear actin filament formation by latrunculin-B (LAT-B), an F-actin depolymerizing compound, resulted in the dose-dependent inhibition of gag mRNA export. The differential subtyping of the mRNA-positive cells confirmed morphologically the effect of LAT-B treatment. The export inhibition was specific to gag mRNA and export of fully spliced HIV-1 tat/rev mRNAs as well as cellular GAPDH mRNA was not affected by the compound.

Conclusions: Nuclear beta-actin bundles are suggested to be functionally involved in the Rev-dependent nucleocytoplasmic transport of intron-containing HIV-1 gag mRNA.

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