The cleavage of Akt/protein kinase B by death receptor signaling is an important event in detachment-induced apoptosis
Department of Cancer Biology
Animals; Anoikis; *Apoptosis; Caspases; Cell Line; Dogs; *Protein-Serine-Threonine Kinases; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-akt; Receptors, TNF-Related Apoptosis-Inducing Ligand; Receptors, Tumor Necrosis Factor; Receptors, Tumor Necrosis Factor, Member 25
Epithelial cells undergo death receptor-dependent apoptosis when detached from matrix, a process termed anoikis. Activation of Akt/protein kinase B (PKB) by matrix attachment protects cells from anoikis. In this study, we establish a link between anoikis and Akt/PKB-mediated survival by demonstrating that Akt/PKB is cleaved by caspases in matrix-detached epithelial cells by a mechanism that involves death receptors. Reduced levels of Akt/PKB protein were observed in detached Madin-Darby canine kidney cells relative to cells attached to collagen. Equivalent levels of Akt/PKB, however, were detected in matrix-adherent and detached cells after inhibition of caspase activity or expression of an Akt/PKB mutant (D108+119A) that is resistant to caspase cleavage. The contribution of death domain-containing proteins to Akt/PKB cleavage was evidenced by the ability of dominant negative Fas-associated death domain to restore normal levels of Akt/PKB in matrix-detached cells. Importantly, expression of a cleavage-resistant Akt/PKB mutant protected matrix-detached cells from apoptosis. These studies suggest that members of the death receptor family promote the caspase-mediated cleavage of Akt/PKB and that this event contributes to anoikis.
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Citation: J Biol Chem. 2001 Sep 14;276(37):34702-7. Epub 2001 Jul 19. Link to article on publisher's site
Bachelder, Robin E.; Wendt, Melissa A.; Fujita, Naoya; Tsuruo, Takashi; and Mercurio, Arthur M., "The cleavage of Akt/protein kinase B by death receptor signaling is an important event in detachment-induced apoptosis" (2001). Cancer Biology Publications and Presentations. Paper 157.