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7050709 
Journal Article 
gamma-H2AX dephosphorylation by protein phosphatase 2A facilitates DNA double-strand break repair 
Chowdhury, D; Keogh, MC; Ishii, H; Peterson, CL; Buratowski, S; Lieberman, J; , 
2005 
1 
Molecular Cell
ISSN: 1097-2765
EISSN: 1097-4164 
English 
16310392 
Phosphorylated histone H2AX (gamma-H2AX) forms foci over large chromatin domains surrounding double-stranded DNA breaks (DSB). These foci recruit DSB repair proteins and dissolve during or after repair is completed. How gamma-H2AX is removed from chromatin remains unknown. Here, we show that protein phosphatase 2A (PP2A) is involved in removing gamma-H2AX foci. The PP2A catalytic subunit [PP2A(C)] and gamma-H2AX coimmunoprecipitate and colocalize in DNA damage foci and PP2A dephosphorylates gamma-H2AX in vitro. The recruitment of PP2A(C) to DNA damage foci is H2AX dependent. When PP2A(C) is inhibited or silenced by RNA interference, gamma-H2AX foci persist, DNA repair is inefficient, and cells are hypersensitive to DNA damage. The effect of PP2A on gamma-H2AX levels is independent of ATM, ATR, or DNA-PK activity.