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Protein phosphatase 2A regulates deoxycytidine kinase activity via Ser‐74 dephosphorylation
Author(s) -
Amsailale Rachid,
Beyaert Maxime,
Smal Caroline,
Janssens Veerle,
Van Den Neste Eric,
Bontemps Françoise
Publication year - 2014
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2014.01.016
Subject(s) - dephosphorylation , okadaic acid , deoxycytidine kinase , protein phosphatase 2 , phosphatase , phosphorylation , kinase , biochemistry , nucleoside , microbiology and biotechnology , chemistry , biology , deoxycytidine , chemotherapy , gemcitabine , genetics
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.