RAD18 directs DNA double-strand break repair by homologous recombination to post-replicative chromatin
Matous Palek, Natalie Palkova, Marta Černá, Klára Horáčková, Milena Hovhannisyan, Markéta Janatová, Sandra Jelínková, Petr Nehasil, Jana Soukupová, Barbora Šťastná, Petra Zemánková, Lenka Foretová, Eva Macháčková, Vera Krutilkova, Spiros Tavandzis, Leona Cerna, Štěpán Chvojka, Monika Koudová, Ondřej Havránek, Jan Novotný, Kamila Veselá, Michal Vočka, Lucie Hrušková, Renáta Michalovská, Denisa Schwetzova, Zdeňka Vlčková, Monika Černá, Markéta Hejnalová, Nikol Jedlickova, Ivan Šubrt, Tomas Zavoral, Marcela Kosařová, Gabriela Vacínová, Mária Janíková, Romana Kratochvílová, Václava Curtisová, Radek Vrtěl, Ondřej Scheinost, Petra Dušková, Viktor Stránecký, Petra Kleiblová, Zdeněk Kleibl, Libor Macůrek
Abstract
RAD18 is an E3 ubiquitin ligase that prevents replication fork collapse by promoting DNA translesion synthesis and template switching. Besides this classical role, RAD18 has been implicated in homologous recombination; however, this function is incompletely understood. Here, we show that RAD18 is recruited to DNA lesions by monoubiquitination of histone H2A at K15 and counteracts accumulation of 53BP1. Super-resolution microscopy revealed that RAD18 localizes to the proximity of DNA double strand breaks and limits the distribution of 53BP1 to the peripheral chromatin nanodomains. Whereas auto-ubiquitination of RAD18 mediated by RAD6 inhibits its recruitment to DNA breaks, interaction with SLF1 promotes RAD18 accumulation at DNA breaks in the post-replicative chromatin by recognition of histone H4K20me0. Surprisingly, suppression of 53BP1 function by RAD18 is not involved in homologous recombination and rather leads to reduction of non-homologous end joining. Instead, we provide evidence that RAD18 promotes HR repair by recruiting the SMC5/6 complex to DNA breaks. Finally, we identified several new loss-of-function mutations in RAD18 in cancer patients suggesting that RAD18 could be involved in cancer development.