Protein phosphatase 2A (PP2A) holoenzymes regulate death-associated protein kinase (DAPK) in ceramide-induced anoikis

Ryan C. Widau, Yijun Jin, Shelley A. Dixon, Brian E. Wadzinski, Patricia J. Gallagher

Research output: Contribution to journalArticle

36 Scopus citations

Abstract

The tumor suppressor, death-associated protein kinase (DAPK), is a Ca 2+/calmodulin-regulated Ser/Thr kinase with an important role in regulating cytoskeletal dynamics. Autophosphorylation within the calmodulin-binding domain at Ser-308 inhibits DAPK catalytic activity. Dephosphorylation of Ser-308 by a previously unknown phosphatase enhances kinase activity and proteasome-mediated degradation of DAPK. In these studies, we identified two holoenzyme forms of protein phosphatase 2A (PP2A), ABαC and ABδC, as DAPK-interacting proteins. These phosphatase holoenzymes dephosphorylate DAPK at Ser-308 in vitro and in vivo resulting in enhanced kinase activity of DAPK. The enzymatic activity of PP2A also negatively regulates DAPK levels by enhancing proteasome-mediated degradation of the kinase. Overexpression of wild type DAPK induces cell rounding and detachment in HEK293 cells; however, this effect is not observed following expression of an inactive DAPK S308E mutant. Finally, activation of DAPK by PP2A was found to be required for ceramide-induced anoikis. Together, our results provide a mechanism by which PP2A and DAPK activities control cell adhesion and anoikis.

Original languageEnglish (US)
Pages (from-to)13827-13838
Number of pages12
JournalJournal of Biological Chemistry
Volume285
Issue number18
DOIs
StatePublished - Apr 30 2010

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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