Figure 1: Formation of beaded apoptopodia by apoptotic human monocytes.

(a) Time-lapse images monitoring THP-1 monocytes undergoing ultraviolet-induced apoptosis. (b) Quantitation of live microscopy data to determine the percentage of apoptotic THP-1 cells that form membrane bleb and/or beaded apoptopodia during 4 h of time-lapse imaging (n=3). (c) Upper, isolation of primary human CD14⁺ cells from peripheral blood mononuclear cells. Lower, primary CD14⁺ cells undergoing spontaneous apoptosis during serum starvation. DIC images of apoptotic THP-1 cells forming uniform beaded apoptopodia (d) or non-uniform beaded apoptopodia (e) 2 h post ultraviolet irradiation. Quantitation of the diameter of vesicle-like structures on each type of beaded apoptopodia is shown on the right. (f) Fragmentation of beaded apoptopodia from apoptotic THP-1 and primary CD14⁺ cells under cultured conditions. (g) Images of apoptotic bodies stained with annexin V (green). (h) Flow cytometry analysis showing each type of cells and apoptotic particles gated according to Supplementary Fig. 3. (i) TO-PRO-3 dye uptake in viable and annexin V⁺ apoptotic THP-1 cells (n=3). (j) TO-PRO-3 uptake and formation of apoptotic bodies from apoptotic THP-1 cells treated with the PANX1 inhibitor trovafloxacin (n=3). (k) Quantitation of the percentage of untreated or trovafloxacin-treated apoptotic THP-1 cells that forms beaded apoptopodia (n=3). Error bars represent s.e.m. Data are representative of at least two independent experiments. P=0.07, unpaired Student’s two-tailed t-test.