Nuclear Exportin Receptor CAS Regulates the NPI-1–Mediated Nuclear Import of HIV-1 Vpr
Figure 5
The siRNA-induced knock down of CAS prevents the nuclear import of Vpr.
(A) CAS-specific siRNA and nonspecific siRNA (negative control) transfections were performed in HeLa cells. After 36 h of treatment with CAS-specific siRNA1 and siRNA2 and the negative control siRNA, cell extracts were prepared and immunoblotting with an anti-CAS antibody was used to determine the transfection efficiencies of the siRNAs. Untreated HeLa cells (-). Actin was included as an internal control. The positions of CAS and actin are indicated. (B) Digitonin-permeabilized HeLa cells, transfected with siRNAs, were incubated with 1 µM GST-GFP-Vpr, 1 µM NPI-1 and 1 µM CAS. After fixation, cells were analyzed by confocal laser scanning microscopy. Bar = 10 µm. (C) Fluorescence intensity per nuclear surface area was quantified in over 80 nuclei from three independent experiments. The bar shows the standard errors of measurements.