Involvement of ATM in homologous recombination after end resection and RAD51 nucleofilament formation

TY - JOUR

T1 - Involvement of ATM in homologous recombination after end resection and RAD51 nucleofilament formation

AU - Bakr, A

AU - Oing, C

AU - Köcher, S

AU - Borgmann, K

AU - Dornreiter, I

AU - Petersen, Cordula

AU - Dikomey, E

AU - Mansour Khalfallah, Wael Yassin

N1 - © The Author(s) 2015. Published by Oxford University Press on behalf of Nucleic Acids Research.

PY - 2015/3/31

Y1 - 2015/3/31

N2 - Ataxia-telangiectasia mutated (ATM) is needed for the initiation of the double-strand break (DSB) repair by homologous recombination (HR). ATM triggers DSB end resection by stimulating the nucleolytic activity of CtIP and MRE11 to generate 3'-ssDNA overhangs, followed by RPA loading and RAD51 nucleofilament formation. Here we show for the first time that ATM is also needed for later steps in HR after RAD51 nucleofilament formation. Inhibition of ATM after completion of end resection did not affect RAD51 nucleofilament formation, but resulted in HR deficiency as evidenced by (i) an increase in the number of residual RAD51/γH2AX foci in both S and G2 cells, (ii) the decrease in HR efficiency as detected by HR repair substrate (pGC), (iii) a reduced SCE rate and (iv) the radiosensitization of cells by PARP inhibition. This newly described role for ATM was found to be dispensable in heterochromatin-associated DSB repair, as KAP1-depletion did not alleviate the HR-deficiency when ATM was inhibited after end resection. Moreover, we demonstrated that ATR can partly compensate for the deficiency in early, but not in later, steps of HR upon ATM inhibition. Taken together, we describe here for the first time that ATM is needed not only for the initiation but also for the completion of HR.

AB - Ataxia-telangiectasia mutated (ATM) is needed for the initiation of the double-strand break (DSB) repair by homologous recombination (HR). ATM triggers DSB end resection by stimulating the nucleolytic activity of CtIP and MRE11 to generate 3'-ssDNA overhangs, followed by RPA loading and RAD51 nucleofilament formation. Here we show for the first time that ATM is also needed for later steps in HR after RAD51 nucleofilament formation. Inhibition of ATM after completion of end resection did not affect RAD51 nucleofilament formation, but resulted in HR deficiency as evidenced by (i) an increase in the number of residual RAD51/γH2AX foci in both S and G2 cells, (ii) the decrease in HR efficiency as detected by HR repair substrate (pGC), (iii) a reduced SCE rate and (iv) the radiosensitization of cells by PARP inhibition. This newly described role for ATM was found to be dispensable in heterochromatin-associated DSB repair, as KAP1-depletion did not alleviate the HR-deficiency when ATM was inhibited after end resection. Moreover, we demonstrated that ATR can partly compensate for the deficiency in early, but not in later, steps of HR upon ATM inhibition. Taken together, we describe here for the first time that ATM is needed not only for the initiation but also for the completion of HR.

U2 - 10.1093/nar/gkv160

DO - 10.1093/nar/gkv160

M3 - SCORING: Journal article

C2 - 25753674

VL - 43

SP - 3154

EP - 3166

JO - NUCLEIC ACIDS RES

JF - NUCLEIC ACIDS RES

SN - 0305-1048

IS - 6

ER -