Figure 2.

Ability of SUN1 variants to restrict HIV-1 infection. (A) SUN1 membrane topology is illustrated in a cell by showing that the N-terminal domain of SUN1 faces the nucleoplasm while the C-terminal domain is in the nuclear lamina or lamina propia. The SUN1 protein is also depicted with the numbers of the amino acid residues at the boundaries of the domains. The SUN1 protein is depicted containing the lamina binding domain (LMNA) (1–138) on the N-terminus, hydrophobic regions, a transmembrane region (316–335), coiled coil domain, and a SUN domain (565–700) on the C-terminus. The different SUN1 N-terminal deletions variants are illustrated. (B) Human HT1080 cells stably expressing wild type and mutant SUN1-FLAG proteins. Stable expression of wild type and mutant SUN1 proteins in human HT1080 cells was analyzed by Western blotting using anti-FLAG antibodies. As loading control, extracts were also Western blotted using anti-GAPDH antibodies. (C) HIV-1 restriction by wild type and mutant SUN1 proteins. HT1080 cells stably expressing wild type and mutant SUN1 proteins were challenged with increasing amounts of HIV-1-GFP. Forty-eight hours post-infection, the percentage of GFP-positive cells was measured using a flow cytometer. Experiments were repeated at least three times and a representative experiment is shown. Fold differences in restriction are shown as the ratio of the area under the curve of the SUN variant to the empty vector pLPCX. Fold values greater than 2 are shown.