Resumen de DNA polymerase κ-dependent DNA synthesis at stalled replication forks is important for CHK1 activation

Rémy Bétous, Marie-Jeanne Pillaire, Laura Pierini, Siem van der Laan, Bénédicte Recolin, Emma Ohl-Séguy, Caixia Guo, Naoko Niimi, Petr Grúz, Takehiko Nohmi, Errol C. Friedberg, Christophe Cazaux, Domenico Maiorano, Jean-Sébastien Hoffmann

• Formation of primed single-stranded DNA at stalled replication forks triggers activation of the replication checkpoint signalling cascade resulting in the ATR-mediated phosphorylation of the Chk1 protein kinase, thus preventing genomic instability. By using siRNA-mediated depletion in human cells and immunodepletion and reconstitution experiments in Xenopus egg extracts, we report that the Y-family translesion (TLS) DNA polymerase kappa (Pol κ) contributes to the replication checkpoint response and is required for recovery after replication stress. We found that Pol κ is implicated in the synthesis of short DNA intermediates at stalled forks, facilitating the recruitment of the 9-1-1 checkpoint clamp. Furthermore, we show that Pol κ interacts with the Rad9 subunit of the 9-1-1 complex. Finally, we show that this novel checkpoint function of Pol κ is required for the maintenance of genomic stability and cell proliferation in unstressed human cells.