Telomere tethering at the nuclear periphery is essential for efficient DNA double strand break repair in subtelomeric region

Abstract

In the yeast Saccharomyces cerevisiae that lacks lamins, the nuclear pore complex (NPC) has been proposed to serve a role in chromatin organization. Here, using fluorescence microscopy in living cells, we show that nuclear pore proteins of the Nup84 core complex, Nup84p, Nup145Cp, Nup120p, and Nup133p, serve to anchor telomere XI-L at the nuclear periphery. The integrity of this complex is shown to be required for repression of a URA3 gene inserted in the subtelomeric region of this chromosome end. Furthermore, altering the integrity of this complex decreases the efficiency of repair of a DNA double-strand break (DSB) only when it is generated in the subtelomeric region, even though the repair machinery is functional. These effects are specific to the Nup84 complex. Our observations thus confirm and extend the role played by the NPC, through the Nup84 complex, in the functional organization of chromatin. They also indicate that anchoring of telomeres is essential for efficient repair of DSBs occurring therein and is important for preserving genome integrity.

Perinuclear tethers license telomeric DSBs for a broad kinesin- and NPC-dependent DNA repair process

“…Deletion of the Nup84 subcomplex components Nup84 or Nup145, or of the perinuclear telomere-tethering protein Esc1, significantly decreased survival of the subtelomeric DSB, as expected ( Fig. 1b; Supplementary Table 1) 21,22,28 . Disruption of the telomere-tethering complex cohibin (composed of Lrs4 and Csm1 proteins) alone or in combination with Esc1 deletion, similarly compromised subtelomeric DSB survival (Fig.…”

“…XI; Fig. 1a) 22,27 . In both of the cases, we introduced galactose-inducible I-SceI endonuclease in cells harbouring a URA3 marker gene flanked by two inverted I-SceI cut sites, which enabled us to confirm successful DSB induction by culturing cells on selective media and monitoring for URA3 reporter loss ( Fig.…”

“…XI were transformed by the I-SceI expression plasmid pKM97 (refs 22,27). This plasmid harbours the I-SceI ORF under control of a galactose-inducible promoter and induction of DSB was performed by plating on galactose media 22 . All subtelomeric (Figs 1b,c,f,h and 4d) or internal (Fig.…”

“…These telomeric clusters do not co-localize with nuclear pore complexes 17 . Intriguingly, the ability to survive a subtelomeric DSB is dependent on Nup84 as well as a number of factors known to anchor telomere clusters to the nuclear envelope 12,13,[18][19][20][21][22] . However, the relationship between perinuclear telomere tethers and nuclear pore subcomplexes in subtelomeric DNA repair remains unknown 12,23 .…”

Nuclear organization in genome stability: SUMO connections

“…Indeed, sites of damage arising from a targeted endonuclease [31] or γ-irradiation [32] are relatively immobile in the mammalian nucleus, suggesting that most DSB repair by non-homologous end joining, does not involve relocalization of damage to sites like PML-NBs. It remains possible, however, that specific pathways of DNA repair require specific nuclear subcompartments, since the efficiency of certain types of repair varies with the chromosomal context in which the damage occurs [35].…”