Protein phosphatase 2A regulates deoxycytidine kinase activity via Ser-74 dephosphorylation.
Deoxycytidine kinase (dCK) is a critical enzyme for activation of anticancer nucleoside analogs. Its activity is controlled via Ser-74 phosphorylation. Here, we investigated which Ser/Thr phosphatase dephosphorylates Ser-74. In cells, the PP1/PP2A inhibitor okadaic acid increased both dCK activity and Ser-74 phosphorylation at concentrations reported to specifically target PP2A. In line with this, purified PP2A, but not PP1, dephosphorylated recombinant pSer-74-dCK. In cell lysates, the Ser-74-dCK phosphatase activity was found to be latent, Mn(2+)-activated, responsive to PP2A inhibitors, and diminished after PP2A-immunodepletion. Use of siRNAs allowed concluding definitively that PP2A constitutively dephosphorylates dCK in cells and negatively regulates its activity.
de Duve Institute & Université Catholique de Louvain, B-1200 Brussels, Belgium.
Rachid
R
Amsailale
de Duve Institute & Université Catholique de Louvain, B-1200 Brussels, Belgium.
Maxime
M
Beyaert
de Duve Institute & Université Catholique de Louvain, B-1200 Brussels, Belgium.
Caroline
C
Smal
Laboratory of Protein Phosphorylation and Proteomics, Department of Cellular and Molecular Medicine, University of Leuven, B-3000 Leuven, Belgium.
Veerle
V
Janssens
de Duve Institute & Université Catholique de Louvain, B-1200 Brussels, Belgium; Department of Hematology, Cliniques Universitaires Saint-Luc & Université Catholique de Louvain, B-1200 Brussels, Belgium.
Eric
E
Van Den Neste
de Duve Institute & Université Catholique de Louvain, B-1200 Brussels, Belgium. Electronic address: francoise.bontemps@uclouvain.be.
Françoise
F
Bontemps
D064007:Ataxia Telangiectasia Mutated Proteins / Q000378:metabolism; D045744:Cell Line, Tumor; D003842:Deoxycytidine Kinase / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D019319:Okadaic Acid / Q000494:pharmacology; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors / Q000502:physiology*; D010766:Phosphorylation; D000071636:Protein Phosphatase 2C; D011499:Protein Processing, Post-Translational; D012694:Serine / Q000378:metabolism
D019319:Okadaic Acid; D012694:Serine; D003842:Deoxycytidine Kinase; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D010749:Phosphoprotein Phosphatases; D000071636:Protein Phosphatase 2C
Deoxycytidine kinase; Nucleoside analog; Protein phosphatase; Ser-74 phosphorylation; Ser/Thr protein phosphatase 2A