CK2 functionally interacts with AKT/PKB to promote the ß-catenin-dependent expression of survivin and enhance cell survival.

ABSTRACT

ß-Catenin is crucial in the canonical Wnt signaling pathway. This pathway is up-regulated by CK2 which is associated with an enhanced expression of the antiapoptotic protein survivin, although the underlying molecular mechanism is unknown. AKT/PKB kinase phosphorylates and promotes ß-catenin transcriptional activity, whereas CK2 hyperactivates AKT by phosphorylation at Ser129; however, the role of this phosphorylation on ß-catenin transcriptional activity and cell survival is unclear. We studied in HEK-293T cells, the effect of CK2-dependent hyperactivation of AKT on cell viability, as well as analyzed ß-catenin subcellular localization and transcriptional activity and survivin expression. CK2α overexpression led to an augmented ß-catenin-dependent transcription and protein levels of survivin, and consequently an enhanced resistance to apoptosis. However, CK2α-enhancing effects were reversed when an AKT mutant deficient in Ser129 phosphorylation by CK2 was co-expressed. Therefore, our results strongly suggest that CK2α-specific enhancement of ß-catenin transcriptional activity as well as cell survival may depend on AKT hyperactivation by CK2.