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Nap1 stimulates homologous recombination by RAD51 and RAD54 in higher-ordered chromatin containing histone H1

2014; Nature Portfolio; Volume: 4; Issue: 1 Linguagem: Inglês

10.1038/srep04863

2045-2322

Shinichi Machida, Motoki Takaku, Masae Ikura, Jiying Sun, Hidekazu Suzuki, Wataru Kobayashi, Aiko Kinomura, Akihisa Osakabe, Hiroaki Tachiwana, Yasunori Horikoshi, Atsuhiko Fukuto, Ryo Matsuda, Kiyoe Ura, Satoshi Tashiro, Tsuyoshi Ikura, Hitoshi Kurumizaka,

PARP inhibition in cancer therapy

Abstract Homologous recombination plays essential roles in mitotic DNA double strand break (DSB) repair and meiotic genetic recombination. In eukaryotes, RAD51 promotes the central homologous-pairing step during homologous recombination, but is not sufficient to overcome the reaction barrier imposed by nucleosomes. RAD54, a member of the ATP-dependent nucleosome remodeling factor family, is required to promote the RAD51-mediated homologous pairing in nucleosomal DNA. In higher eukaryotes, most nucleosomes form higher-ordered chromatin containing the linker histone H1. However, the mechanism by which RAD51/RAD54-mediated homologous pairing occurs in higher-ordered chromatin has not been elucidated. In this study, we found that a histone chaperone, Nap1, accumulates on DSB sites in human cells and DSB repair is substantially decreased in Nap1-knockdown cells. We determined that Nap1 binds to RAD54, enhances the RAD54-mediated nucleosome remodeling by evicting histone H1 and eventually stimulates the RAD51-mediated homologous pairing in higher-ordered chromatin containing histone H1.