Impaired 53BP1/RIF1 DSB mediated end-protection stimulates CtIP-dependent end resection and switches the repair to PARP1-dependent end joining in G1
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Impaired 53BP1/RIF1 DSB mediated end-protection stimulates CtIP-dependent end resection and switches the repair to PARP1-dependent end joining in G1. / Bakr, Ali; Köcher, Sabrina; Volquardsen, Jennifer; Petersen, Cordula; Borgmann, Kerstin; Dikomey, Ekkehard; Rothkamm, Kai; Mansour Khalfallah, Wael Yassin.
In: ONCOTARGET, Vol. 7, No. 36, 06.09.2016, p. 57679-57693.Research output: SCORING: Contribution to journal › SCORING: Journal article › Research › peer-review
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TY - JOUR
T1 - Impaired 53BP1/RIF1 DSB mediated end-protection stimulates CtIP-dependent end resection and switches the repair to PARP1-dependent end joining in G1
AU - Bakr, Ali
AU - Köcher, Sabrina
AU - Volquardsen, Jennifer
AU - Petersen, Cordula
AU - Borgmann, Kerstin
AU - Dikomey, Ekkehard
AU - Rothkamm, Kai
AU - Mansour Khalfallah, Wael Yassin
PY - 2016/9/6
Y1 - 2016/9/6
N2 - End processing at DNA double strand breaks (DSB) is a decisive step in repair pathway selection. Here, we investigated the role of 53BP1/RIF1 in limiting BRCA1/CtIP-mediated end resection to control DSB repair pathway choice. ATM orchestrates this process through 53BP1 phosphorylation to promote RIF1 recruitment. As cells enter S/G2-phase, end resection is activated, which displaces pATM from DSB sites and diminishes 53BP1 phosphorylation and RIF1 recruitment. Consistently, the kinetics of ATM and 53BP1 phosphorylation in S/G2-phase concur. We show that defective 53BP1/RIF1-mediated DSB end-protection in G1-phase stimulates CtIP/MRE11-dependent end-resection, which requires Polo-like kinase 3. This end resection activity in G1 was shown to produce only short tracks of ssDNA overhangs, as evidenced by the findings that in 53BP1 depleted cells, (i) RPA focus intensity was significantly lower in G1 compared to that in S/G2 phase, and (ii) EXO1 knockdown did not alter either number or intensity of RPA foci in G1 but significantly decreased the RPA focus intensity in S/G2 phase. Importantly, we report that the observed DSB end resection in G1 phase inhibits DNA-PK-dependent nonhomologous end joining but is not sufficient to stimulate HR. Instead, it switches the repair to the alternative PARP1-dependent end joining pathway.
AB - End processing at DNA double strand breaks (DSB) is a decisive step in repair pathway selection. Here, we investigated the role of 53BP1/RIF1 in limiting BRCA1/CtIP-mediated end resection to control DSB repair pathway choice. ATM orchestrates this process through 53BP1 phosphorylation to promote RIF1 recruitment. As cells enter S/G2-phase, end resection is activated, which displaces pATM from DSB sites and diminishes 53BP1 phosphorylation and RIF1 recruitment. Consistently, the kinetics of ATM and 53BP1 phosphorylation in S/G2-phase concur. We show that defective 53BP1/RIF1-mediated DSB end-protection in G1-phase stimulates CtIP/MRE11-dependent end-resection, which requires Polo-like kinase 3. This end resection activity in G1 was shown to produce only short tracks of ssDNA overhangs, as evidenced by the findings that in 53BP1 depleted cells, (i) RPA focus intensity was significantly lower in G1 compared to that in S/G2 phase, and (ii) EXO1 knockdown did not alter either number or intensity of RPA foci in G1 but significantly decreased the RPA focus intensity in S/G2 phase. Importantly, we report that the observed DSB end resection in G1 phase inhibits DNA-PK-dependent nonhomologous end joining but is not sufficient to stimulate HR. Instead, it switches the repair to the alternative PARP1-dependent end joining pathway.
U2 - 10.18632/oncotarget.11023
DO - 10.18632/oncotarget.11023
M3 - SCORING: Journal article
C2 - 27494840
VL - 7
SP - 57679
EP - 57693
JO - ONCOTARGET
JF - ONCOTARGET
SN - 1949-2553
IS - 36
ER -
