Endothelial Galectin-1 Binds to Specific Glycans on Nipah Virus Fusion Protein and Inhibits Maturation, Mobility, and Function to Block Syncytia Formation
Figure 5
Galectin-1 inhibits function of mature NiV-F.
A, Chlorpromazine inhibits maturation of NiV-F0. PK-13 were transfected with NiV-F in the absence or presence of chlorpromazine (50µM). Cells were incubated overnight and NiV-F0 and NiV-F1 detected by immunoblotting. B, Galectin-1 inhibits heterologous cell fusion in the presence of chlorpromazine. BSRT7 ephrinB2 positive cells were added to a monolayer of PK13 cells transfected with NiV-F, NiV-G and a luciferase construct with a T7 dependent promoter in the presence or absence of chlorpromazine (50µM) and galectin-1 (20µM). * p = 0.0002, calculated using Student's t test. C, Fusion kinetics in the presence or absence of galectin-1. NiV-G and NiV-F were expressed in effector PK13 cells, and the relative rate of fusion assessed on target 293T cells loaded with CCF2 dye. Relative fusion is the ratio of blue to green fluorescence from NiV-G and NiV-F-transfected effector cells minus the ratio of background blue to green fluorescence from empty-vector (pcDNA3)-transfected cells. Each data point is the mean of three independent experiments. D, Galectin-1 inhibits the ability of NiV-F to be triggered for membrane fusion. CHO cells expressing NiV-F and NiV-G were mixed with CHO cells (negative control, grey shaded) or CHOB2 cells (ephrinB2 positive, black line) for 1.5 hr at 4°C. Cell mixtures were brought to 37°C or kept at 4°C for 1.5 hr with 1 µM biotinylated HR2 peptide, in the presence or absence of galectin-1GG; top, 4°C without and with galectin-1; bottom, 37°C without and with galectin-1. E, Inhibition of F triggering at 37°C; data are mean fluorescence intensity of triplicate determinations ± SEM. See also Supplementary Figure S1.