Fig. 6: The BRCA2–MCM10 association suppresses PRIMPOL-mediated repriming and ssDNA gap formation after DNA damage.

a Effect of PRIMPOL depletion on replication fork progression in stable U2OS cells selectively expressing exogenous WT vs ΔCC mutant MCM10 proteins before and after IR. The endogenous MCM10 was depleted together with PRIMPOL with siRNAs targeting the 3′-UTR of its mRNA. b Effect of S1 nuclease treatment on detected replication tract length in the above cells after IR. Data in (a) and (b) are presented as mean ± s.d., with the number of dots shown below each column. P values are calculated using two-tailed unpaired Student’s t test. Similar results were obtained in n = 2 independent experiments. c A proposed model for the role of BRCA2 and the BRCA2–MCM10 association in replication fork progression after DNA damage. BRCA2 is recruited to the replication fork via its association with MCM10. When the fork encounters a lesion, polymerase ε stalls, whereas the MCM2-7 helicase complex continues to unwind downstream DNA, leading to excessive ssDNA formation. RPA binds to the ssDNA and may recruit PRIMPOL; however, PRIMPOL recruitment is prevented by BRCA2, which can displace RPA from ssDNA. When BRCA2 is lost or the BRCA2–MCM10 association is compromised, increased and/or persistent presence of RPA on ssDNA leads to PRIMPOL recruitment, hence repriming of DNA synthesis downstream of the lesion and formation of ssDNA gaps. See text for further details.