Fig. 6

Spike S1 augments ATP-dependent Ca²⁺ dynamics via Cx43 hemichannels. (A-D) Representative plots of relative changes in Ca²⁺ signal over time induced by 100 µM ATP (light blue background) in HeLa-parental (A), HeLa-Cx43^GFP (B), HeLa-Cx43^GFP/ACE2^mCherry (C) or HeLa-ACE2^mCherry (D) cells under control conditions (white circles) or treated with 50 pM spike S1 for 24 h (red circles). (E-H) Averaged data normalized to the control conditions (dashed line) of basal Ca²⁺ signal (E), ATP-induced peak amplitude normalized to basal Fura-2 ratio (F), integrated ATP-induced Fura-2 ratio response (G) and altered basal Fura-2 ratio (H) of HeLa-parental, HeLa-Cx43^GFP, HeLa-Cx43^GFP/ACE2^mCherry or HeLa-ACE2^mCherry treated with 50 pM spike S1 for 24 h. *p < 0.05, **p < 0.01; effect of spike S1 compared to control (one-way ANOVA followed by Tukey’s post-hoc test). Data were obtained from at least three independent experiments with two repeats each (≥ 12 cells analyzed for each repeat)