‘Off-pore’ nucleoporins relocalize heterochromatic breaks through phase separation

Abstract

SummaryHeterochromatin mostly comprises repeated DNA sequences prone to ectopic recombination. InDrosophilacells, ‘safe’ homologous recombination (HR) repair of heterochromatic double-strand breaks (DSBs) requires relocalization of repair sites to the nuclear periphery before Rad51 recruitment and strand invasion. Relocalization is driven by nuclear actin filaments and myosins, while anchoring is mediated by the Nup107 complex at nuclear pores. Here, we show an additional ‘off pore’ role of nucleoporins in heterochromatin repair. Sec13 and Nup88 independently recruit Nup98 to DSBs before relocalization and downstream from the Smc5/6 complex and SUMOylation. Remarkably, the phase separation properties of Nup98 are required and sufficient to induce the mobilization of repair sites and to exclude Rad51, thus preventing aberrant recombination while facilitating HR repair. Disrupting this pathway results in heterochromatin repair defects, revealing a novel role for nucleoporins and phase separation in nuclear dynamics and genome integrity in a multicellular eukaryote.HighlightsNup88, Nup98 and Sec13 are required for relocalization of heterochromatic DSBsNup88 and Sec13 independently recruit Nup98 to DSBs downstream from Smc5/6Nup98 promotes relocalization and excludes Rad51 from the heterochromatin domainPhase separation by Nup98 is required and sufficient for relocalization and Rad51 exclusion