Abstract 1779: BRCA2 interacts with an essential replication factor, MCM10.

Abstract The BRCA2 (Breast Cancer 2, early onset) gene is implicated in a variety of familial cancers. Loss of BRCA2 function results in severe defects in DNA double-strand break repair, DNA damage-induced checkpoint response and the stability of stalled DNA replication forks, all of which are important for genomic stability. About 50% of BRCA2 is associated with PALB2 (partner and localizer of BRCA2), which anchors BRCA2 onto chromatin and directs its recruitment to DNA damage sites. By tandem affinity purification of PALB2 we identified MCM10, an essential DNA replication factor, as a component of the PALB2/BRCA2 complex. MCM10 promotes initiation of DNA replication through binding to MCM2-7 helicase complex and recruiting the initial DNA polymerase, pol α, to replication origins. Interestingly, we found that MCM10 binds to BRCA2 instead of PALB2 in the complex. Cells depleted of BRCA2 or MCM10 showed similar instability of stalled replication forks, indicating possible cooperation between the two proteins in fork stabilization following replication stress. Moreover, DNA damage-induced CHK1 activation is markedly reduced in both BRCA2- and MCM10-depleted cells even though RPA (replication protein A) is hyperphosphorylated. Our findings suggest that BRCA2 checkpoint function may be mediated through MCM10 and their interaction may be important for stalled replication fork stability. Domain mapping experiments showed that an evolutionarily conserved coiled-coil motif in the N-terminus of MCM10 which is required for BRCA2 binding and that BRCA2 has at least two MCM10-binding sites, both in its central region. BRCA2 and MCM10 mutants lacking these interaction domains will be used to further test the functional relevance of their interaction. Citation Format: Allen L. Alcivar, Jianglin Ma, Bing Xia. BRCA2 interacts with an essential replication factor, MCM10. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1779. doi:10.1158/1538-7445.AM2013-1779