Apoptosis, BH3 Interacting Domain Death Agonist Protein, Casein Kinase II, Caspase 8, Enzyme Activation, Fluorescence Resonance Energy Transfer, Hela Cells, Humans, Kinetics, Protein Kinase Inhibitors, Protein Structure, Tertiary, Signal Transduction, Substrate Specificity, TNF-Related Apoptosis-Inducing Ligand, Time Factors
In the present study, we quantitatively analysed the interface between apoptosis initiation and execution by determining caspase-8 activation, Bid cleavage and mitochondrial engagement (onset of mitochondrial depolarisation) in individual HeLa cervical cancer cells following exposure to tumour-necrosis-factor-related apoptosis-inducing ligand (TRAIL). Employing resonance-energy-transfer probes containing either the caspase-8 recognition site IETD or full-length Bid, we observed a significant delay between the times of caspase-8 activation and Bid cleavage, suggesting the existence of control steps separating these two processes. Subsequent analyses suggested that the divergence of caspase-8 activation and Bid cleavage are critically controlled by kinase signalling: inhibiting protein kinase CK2 by using 5,6-dichloro-l-(beta-D-ribofuranosyl-1)-benzimidazole (DRB) or by overexpression of a dominant-negative CK2alpha catalytic subunit largely eliminated the lag time between caspase-8 activation and Bid cleavage. We conclude that caspase-8 activation and Bid cleavage are temporally uncoupled events, providing transient tolerance to caspase-8 activities.
Physics | Physiology
Hellwig CT, Ludwig-Galezowska AH, Concannon CG, Litchfield DW, Prehn JHM, Rehm M. Activity of protein kinase CK2 uncouples Bid cleavage from caspase-8 activation. Journal of Cell Science. 2010;23(9):1401-6 epub.