Analysis of perinuclear concentration of tetherin by Vpu and ROD10 Env. (A) HeLa cells were incubated with anti-tetherin antibody at 4°C for 1 hour, followed by incubation at 37°C for either 15 or 45 minutes to allow endocytosis of antibody-tetherin complexes. The antibody was found in a perinuclear region by 15 minutes (arrowed), but became more diffuse by 45 minutes, suggesting that tetherin quickly exits this compartment and recycles back to the plasma membrane. Scale bars represent 10 μM. (B) HIV-1 VLPs produced in 293A cells in the presence of 100 ng of wild-type (WT) or YY-AA tetherin, with and without co-transfection of 2 μg Vpu (pCMV-Vphu). Expression of proteins was confirmed by Western blotting with specific antibodies; tetherin levels were visualized for both untreated and PNGase F treated cell lysates. Mean +/- SEM fold-enhancement of VLP release by Vpu is shown in presence of tetherin or tetherin (YY-AA), n = 2. (C) HeLa cells expressing EGFP-tetherin or EGFP-tetherin(YY-AA) were incubated for 1.5 hours, with or without 20 μg/ml cycloheximide, and subsequently fixed, permeabilized, and stained with anti-EGFP antibody. In the absence of drug, both WT and YY-AA EGFP-tetherin proteins were found at the cell surface and in a perinuclear region (arrowed). After cycloheximide treatment, only EGFP-tetherin produced this population, with EGFP-tetherin(YY-AA) forming a more punctuate pattern, dispersed throughout the cytoplasm. Two different cells are shown for the drug treatment. Scale bars represent 10 μM. (D) HeLa cells were co-transfected with 60 ng EGFP-tetherin(YY-AA) and 2 μg of expression plasmids for either Vphu-HcRed or ROD10 Env. Cells were incubated with or without cycloheximide, as above, and subsequently fixed, permeabilized, and stained with anti-EGFP (green), anti-TGN46 (blue) and anti-HIV-2 Env (red) antibodies. Vpu was detected by HcRed expression (red). EGFP-tetherin(YY-AA) was concentrated in a perinuclear compartment by Vpu or ROD10 Env, overlapping with the TGN marker, irrespective of cycloheximide treatment. Scale bars represent 10 μM.