Spatio-temporal dynamic analysis of bid activation and apoptosis induced by alkaline condition in human lung adenocarcinoma cell.
Activation of initiator and effector caspases and Bid cleavage are apoptotic characteristic features. They are associated with cell alkalization or acidification in some models of apoptosis. The alteration of culture conditions such as extracellular pH value and the overexpression of Bid plasmids may induce cell apoptosis. In present report, we used fluorescence confocal imaging and fluorescence resonance energy transfer (FRET) techniques based on green fluorescent proteins (GFPs) to monitor the spatio-temporal dynamics of Bid translocation and caspase-3 activation in real time in living human lung adenocarcinoma (ASTC-a-1) cells under neutral (pH 7.4) and alkaline (pH 8.0) conditions. The cells transfected with Bid-CFP plasmid did not show apoptotic characteristics for 96 hours under an atmosphere of 95% air, 5% CO(2) at pH 7.4 and 37 degrees C, implying that the overexpression of Bid-CFP plasmid does not induce cell apoptosis. However, all the cells underwent apoptosis after being placed in the alkaline culture (pH 8.0). The dynamic results in single living cell showed that the alkaline condition at pH of 8.0 induced Bid cleavage and tBid translocation to mitochondria at about 1.5 hour, and then induced the caspase-3 activation and cell apoptosis. These results show that the alkaline sondition (pH=8.0) induces cell apoptosis by activating caspase-8, which cleaves Bid to tBid, tBid translocation to mitochondria, and then activating the caspase-3 in the ASTC-a-1 cells.
Chen
Tongsheng
T
MOE Key Liboratory of Laser Life Science and Institute of Laser Life Science, South China Normal University, Guangzhou, China.
Wang
Jinjun
J
Xing
Da
D
Chen
Wei R
WR
D000230:Adenocarcinoma / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D000468:Alkalies; D017209:Apoptosis; D051023:BH3 Interacting Domain Death Agonist Protein / Q000235:genetics / Q000378:metabolism*; D053148:Caspase 3 / Q000378:metabolism; D045744:Cell Line, Tumor; D004789:Enzyme Activation; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008175:Lung Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D010957:Plasmids / Q000235:genetics; D021381:Protein Transport; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism
D000468:Alkalies; D051023:BH3 Interacting Domain Death Agonist Protein; D011994:Recombinant Proteins; D053148:Caspase 3