Figure 3

Imatinib delayed Spike mediated syncytia formation. (a) Scheme of cell-fusion-assay. HEK293T were transfected with plasmids containing either Fos-YFPc and Spike or Jun-YFPn and hACE2. The transcription factors Fos-YFPc and Jun-YFPn are located inside the nucleus; while hACE2 and Spike are localized at the cell-membrane. When cells mixed together, interaction of hACE2 and Spike lead to cell-fusion. Upon cell fusion Fos-YFPc and Jun-YFPn are heterodimerized and emit fluorescence signals. (b) HEK293T cell were transfected with either Fos-YFPc or Jun-YFPn in the presence or absence of hACE2 and Spike. After 2 days, cells were mixed and emitted YFP nuclear signal only in the presence of both hACE2 and Spike. Images represent fusion event 5 h after mixing of the cells. (c) Imatinib delayed Spike-hACE2 mediated fusion. HEK293T cells were transfected as done in panel (b) and 2 days later were harvested, counted, and treated with the indicated drugs for 2 h. Next, cells were mixed and the plates were immediately transferred in IncuCyte-Incubator. The fluorescens signal was monitored every 30 min and calculated by IncuCyte-software. (d) In TMPRSS2-positive cells, imatinib reduced the kinetic of syncytia formation. HEK293T were transfected with either mix of Fos-YFPc and Spike or Jun-YFPn, TMPRSS2 and hACE2. The data in panels (b) and (c) (N = 2) were analyzed with Two-Way ANOVA with Bonferroni multiple comparison and each represents one of three biological replicates: *p ≤ 0.05; **p ≤ 0.01; ***p ≤ 0.001; ****p ≤ 0.0001.