Temporal and spatial characteristics of bid and bax translocation during UV-induced apoptosis

Abstract

UV irradiation is a DNA-damage agent that triggers apoptosis through both the membrane death receptor and the mitochondrial apoptotic signaling pathways. Bid and Bax are two important proapoptotic members of the Bcl-2 family, localize largely in the cytoplasm and redistribute to mitochondria in response to most apoptotic stimuli. Cells deficient in Bax are resistant to UV-induced apoptosis, cells deficient in Bid are less susceptible than normal cells in response to DNA damage. Thus, studying characteristics of Bid and Bax translocation by UV irradiation is very important for us to understand the cellular signaling mechanisms mediating UV-induced apoptosis. In this study, to investigate Bid and Bax translocation in real time in a single cell by UV irradiation, we transfected Bid-CFP, YFP-Bax and DsRed-Mit into human lung adenocarcinoma cells (ASTC-a-1), then observed temporal and spatial characteristics of Bid and Bax translocation by laser confocal scanning microscope imaging technique. Our results showed that Bax translocation was earlier than Bid translocation and the average duration of Bax translocation was about 20-30 min during UV-induced apoptosis.