Fig. 1: Evolution of the nanoscale organization of calreticulin, PS and CD47 during apoptosis.

HeLa cells, viable or 4 h post-UVB-irradiation were stained and imaged by STORM. Bright-field imaging (BF) was used to differentiate healthy cell from apoptotic cell. a–c CD47 (magenta) and calreticulin (green) were detected with an anti-CD47 antibody (B6H12) labeled with Alexa Fluor 647 (A647) and with an anti-calreticulin antibody (PA1-902A) revealed by secondary antibodies labeled with Alexa Fluor 532 (A532). Cell 1 (b) and cell 2 (c) illustrate the clustering of CRT concomitant with the progression of apoptosis. d Phosphatidylserine (magenta) and calreticulin (green) were detected with biotinylated annexin V and an anti-calreticulin antibody (PA1-902A) and revealed by streptavidin labeled with A647 and secondary antibodies labeled with A532 fluorophores, respectively. The white arrow points to a specific area where CRT and PS are excluded. Scale bar, 10 μm on BF images and 5 µm on STORM images. e 2D co-localization was quantified by Spearman’s rank correlation. Ten cells per condition are analyzed from independent experiments (n ≥ 4). Co-localizations were measured on the whole cells. Exact significant P values (two-sided unpaired t test with Welch’s correction) are mentioned as indicated, and n.s. p > 0.05. Each dot corresponds to one cell. Means with SD are shown. Experimental, artificial positive and artificial negative controls were obtained as described in the methods section and represented in Fig. S3a, b. f Violin plots show representative distribution of CRT cluster diameter measured on the cells represented in Fig. 1a-c. Segmentation and quantification of calreticulin cluster diameter were determined as shown in Fig. S3.c.