ATM/ATR-mediated phosphorylation of PALB2 promotes RAD51 function.
DNA damage activates the ATM and ATR kinases that coordinate checkpoint and DNA repair pathways. An essential step in homology-directed repair (HDR) of DNA breaks is the formation of RAD51 nucleofilaments mediated by PALB2-BRCA2; however, roles of ATM and ATR in this critical step of HDR are poorly understood. Here, we show that PALB2 is markedly phosphorylated in response to genotoxic stresses such as ionizing radiation and hydroxyurea. This response is mediated by the ATM and ATR kinases through three N-terminal S/Q-sites in PALB2, the consensus target sites for ATM and ATR Importantly, a phospho-deficient PALB2 mutant is unable to support proper RAD51 foci formation, a key PALB2 regulated repair event, whereas a phospho-mimicking PALB2 version supports RAD51 foci formation. Moreover, phospho-deficient PALB2 is less potent in HDR than wild-type PALB2. Further, this mutation reveals a separation in PALB2 function, as the PALB2-dependent checkpoint response is normal in cells expressing the phospho-deficient PALB2 mutant. Collectively, our findings highlight a critical importance of PALB2 phosphorylation as a novel regulatory step in genome maintenance after genotoxic stress.
Biotech Research and Innovation Centre, University of Copenhagen, Copenhagen, Denmark.
Johanna K
JK
Ahlskog
Biotech Research and Innovation Centre, University of Copenhagen, Copenhagen, Denmark.
Brian D
BD
Larsen
Biotech Research and Innovation Centre, University of Copenhagen, Copenhagen, Denmark.
Kavya
K
Achanta
Biotech Research and Innovation Centre, University of Copenhagen, Copenhagen, Denmark claus.storgaard@bric.ku.dk.
Claus S
0000-0001-6022-9710
CS
Sørensen
D000199:Actins / Q000378:metabolism; D064007:Ataxia Telangiectasia Mutated Proteins / Q000378:metabolism*; D002460:Cell Line; D004249:DNA Damage / Q000187:drug effects / Q000528:radiation effects; D000076164:Fanconi Anemia Complementation Group N Protein; D042822:Genomic Instability; D006801:Humans; D006918:Hydroxyurea / Q000494:pharmacology; D009687:Nuclear Proteins / Q000737:chemistry / Q000378:metabolism*; D010766:Phosphorylation; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D051135:Rad51 Recombinase / Q000378:metabolism*; D011839:Radiation, Ionizing; D012694:Serine / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000737:chemistry / Q000378:metabolism*
D000199:Actins; D000076164:Fanconi Anemia Complementation Group N Protein; D009687:Nuclear Proteins; C512790:PALB2 protein, human; D025521:Tumor Suppressor Proteins; D012694:Serine; C576597:ATR protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D051135:Rad51 Recombinase; D006918:Hydroxyurea
ATM; ATR; DNA damage response; PALB2 phosphorylation; RAD51