Figure 3

Blue light dependent apoptosis activated by Opto-Caspase8. (A) Active caspase8 was detected by fluorescence microscope labeled by FAM-LETD-FMK caspase-8 in HEK293T cells. Blue light (50 μmol m⁻² s⁻¹ for 3 h) treated transfected cells were incubated with FAM-LETD-FMK caspase-8 before capturing pictures, CiB1N-Caspase8 and the empty vector pci myc were co-transfected as control. (B) Caspase8 activity analysis in (A), activities = fluorescent intensity of caspase8 in blue/fluorescent intensity of caspase8 in dark. Data are presented as mean ± SD (n = 3). Student’s t test: ***p < 0.001. (C) Time course of FAM-LETD-FMK labeled caspase-8 activity assay in HEK293T cells. Same operation were conducted as showed in (A,B). Data are presented as mean ± SD (n = 3). Student’s t test: ***p < 0.001. (D) Cell viability analysis in HeLa cells expressed Opto-Caspase8 V1 or Opto-Caspase8 V2 by flow cytometry. Alexa Fluor® 488 annexin and PI was used to detect apoptosis cells. The transfected cells were either shielded or exposed to continuous blue light (50 μmol m⁻² s⁻¹) for 3 h. (E) Relative cell death rate analysis in (D). Rate = number of apoptosis cells in blue/number of apoptosis cells in dark. Data are presented as mean ± SD (n = 3). Student’s t test: ***p < 0.001.