Fig. 1

Spike S1 augments the activity of Cx43 hemichannels. (A) Averaged Etd uptake rate normalized with the control condition (dashed line) by HeLa-Cx43^GFP cells treated for several periods with 10 pM (blue circles) or 50 pM (red circles) spike S1. *p < 0.05, **p < 0.01; effect of spike S1 compared to control (two-way ANOVA followed by Tukey’s post-hoc test). (B) Averaged Etd uptake rate normalized with the control condition (dashed line) by HeLa-Cx43^GFP cells treated for 24 h with different concentrations of spike S1. *p < 0.05, **p < 0.01; effect of spike S1 compared to control (one-way ANOVA followed by Tukey’s post-hoc test). (C-D) Representative images depicting the phase view merged with Cx43^GFP (green) and Etd (red, 5 µM and 10 min of exposure) labeling by HeLa-Cx43^GFP cells under control conditions (C) or treated with 50 pM spike S1 for 24 h (D). (E-F) Etd staining by HeLa-Cx43^GFP cells showed in C and D. (G) Time-lapse measurements of Etd uptake by HeLa-Cx43^GFP cells under control conditions (white circles) or treated with 50 pM spike S1 for 24 h (red circles). (H) Time-lapse measurements of Etd uptake by HeLa-Cx43^GFP cells under control conditions acutely stimulated with 50 pM spike S1. Etd fluorescence was recorded in basal conditions for 3 min (white outline) and then an acute stimulation was performed during the following 5 min (red outline). (I) Averaged Etd uptake rate normalized with the control condition (dashed line) by HeLa-Cx43^GFP cells acutely stimulated with different concentrations of spike S1. (J) Averaged Etd uptake rate normalized with the control condition (dashed line) by HeLa-parental cells treated for 24 h with different concentrations of spike S1. Data were obtained from at least three independent experiments with three or more repeats each (≥ 20 cells analyzed for each repeat). Calibration bar = 12 μm