FIGURE 3.
Sms2 augmented HIV-1 Env-mediated cell-cell fusion susceptibility. A, HIV-1 Env-mediated cell-cell fusion assay was performed using Sms1- or Sms2-reconstituted cells as the target cells. The target cells (ZS, ZS/Sms1, and ZS/Sms2 cells) that expressed CD4/CCR5 and the LTR-luciferase gene were cultured for 4 h with the effector HEK293 cells that expressed EnvJRFL (CCR5-tropic) and the HIV-1 Tat gene (left panel). The target cells that expressed CD4/CXCR4 and the reporter gene were also cultured for 4 h with other effector HEK293 cells that expressed EnvNL4-3 (CXCR4-tropic) and the HIV-1 Tat gene (right panel). Fusion susceptibility was determined from luciferase activity using the reporter gene activation assay. Values represent the mean ± S.D. from three independent experiments. *, p < 0.01; NS, not significant. B, VSV-G Env-mediated cell-cell fusion assay was performed. The target cells (ZS, ZS/Sms1, and ZS/Sms2 cells) that expressed the LTR-luciferase gene were cultured for 4 h with the effector HEK293 cells that expressed VSV-G Env and the HIV-1 Tat gene. Fusion susceptibility was determined from luciferase activity using the reporter gene activation assay. Values are represented as the mean ± S.D. from three independent experiments. C, cell-surface expression levels of CD4/CCR5 or CD4/CXCR4 in each target cell (ZS, ZS/Sms1, and ZS/Sms2 cells) were analyzed by flow cytometry using each specific antibody (filled histogram). Open histograms indicate the isotype control. Ten thousand cells were measured in each sample. D, values represent the mean ± S.D. from three independent experiments in C.