Skip to main content
. 2009 Apr 10;284(15):9845–9853. doi: 10.1074/jbc.M809272200

FIGURE 2.

FIGURE 2.

PP5 participates in the dephosphorylation of 53BP1 at Ser-25 and Ser-1778 after the DNA repair process. A, to identify the kinase responsible for the phosphorylation of 53BP1 at Ser-1778, U2OS cells were transfected with siRNAs against control, ATM, and ATR using Lipofectamine reagent. After 48 h, the cells were treated with 200 ng/ml NCS for 1 h, and the phosphorylation status of 53BP1 at Ser-1778 in cell extracts was determined with anti-phospho-53BP1-Ser-1778. In the bottom two panels, depletion of ATM or ATR by siRNA was demonstrated by immunoblotting of cell lysates with antibodies against ATM or ATR. B, dephosphorylation of 53BP1 was mediated specifically by PP5. U2OS and U2OS-PO cells were treated with NCS (200 ng/ml) and then harvested 1, 3, 6, 12, or 24 h later. The phosphorylation patterns of 53BP1 and BRCA1 were analyzed by Western blotting using the indicated antibodies. C, graphs show the quantification of the levels of 53BP1 phosphorylated on Ser-25 and Ser-1778 and BRCA1 phosphorylated on Ser-1524 shown in B at the indicated time point. The data were normalized to the untreated U2OS-PO cells (as the value of 1) and are the mean ± S.D. of three independent experiments.