Nuclear position dictates DNA repair pathway choice.

Charlène Lemaître,Pascal Kessler,Evi Soutoglou,Vincent Heyer,Audrey Furst,Kathleen M Attwood,Katerina Tsouroula,Leonid Andronov,Graham Dellaire,Mélanie Rogier,Bernardo Reina-San-Martin,Tibor Pankotai,Bruno Klaholz,Anastazja Grabarz

doi:10.1101/gad.248369.114

Abstract

Faithful DNA repair is essential to avoid chromosomal rearrangements and promote genome integrity. Nuclear organization has emerged as a key parameter in the formation of chromosomal translocations, yet little is known as to whether DNA repair can efficiently occur throughout the nucleus and whether it is affected by the location of the lesion. Here, we induce DNA double-strand breaks (DSBs) at different nuclear compartments and follow their fate. We demonstrate that DSBs induced at the nuclear membrane (but not at nuclear pores or nuclear interior) fail to rapidly activate the DNA damage response (DDR) and repair by homologous recombination (HR). Real-time and superresolution imaging reveal that DNA DSBs within lamina-associated domains do not migrate to more permissive environments for HR, like the nuclear pores or the nuclear interior, but instead are repaired in situ by alternative end-joining. Our results are consistent with a model in which nuclear position dictates the choice of DNA repair pathway, thus revealing a new level of regulation in DSB repair controlled by spatial organization of DNA within the nucleus.

Highlights

Cells continuously experience stress and damage from exogenous sources, such as UV light or irradiation, and endogenous sources, such as oxidative by-products of cellular metabolism (Jackson and Bartek 2009)
To investigate the impact of nuclear compartmentalization on DNA repair, we induced double-strand breaks (DSBs) in chromatin associated with the inner nuclear membrane and tested the consequences of nuclear position in DNA damage response (DDR) kinetics and DNA repair efficiency
We showed that breaks occurring in chromatin that surrounds the nuclear membrane do not migrate to other regions of the nucleus, not even to other domains within the nuclear periphery, but rather are repaired within the lamina, where the break occurred by nonhomologous end-joining (NHEJ) and alternative end-joining (A-EJ)

Summary

Introduction

Cells continuously experience stress and damage from exogenous sources, such as UV light or irradiation, and endogenous sources, such as oxidative by-products of cellular metabolism (Jackson and Bartek 2009). Multiple DSBs on several chromosomes are repaired individually and do not meet on shared repair centers or move toward the nuclear periphery (Soutoglou et al 2007) In line with these observations, spatial proximity of DSBs in the nucleus is a key parameter that affects the frequency of formation of chromosomal translocations in mammals (Roukos et al 2013; Roukos and Misteli 2014). Contrary to what was observed in yeast, DNA DSBs within lamina-associated domains (LADs) do not migrate to more permissive environments for HR, like the nuclear pores or the nuclear interior Instead, they are repaired in situ by NHEJ or alternative end-joining (A-EJ). Our data reveal a new level of regulation in DSB repair pathway choice controlled by spatial organization of DNA in the nucleus

Methods

Results

Conclusion