CENP-A chromatin disassembly in stressed and senescent murine cells

Sabrine Hédouin,Giacomo Grillo,Claire Francastel,Guillaume Velasco,Ivana Ivkovic

doi:10.1038/srep42520

Abstract

Centromeres are chromosomal domains essential for genomic stability. We report here the remarkable transcriptional and epigenetic perturbations at murine centromeres in genotoxic stress conditions. A strong and selective transcriptional activation of centromeric repeats is detected within hours. This is followed by disorganization of centromeres with striking delocalization of nucleosomal CENP-A, the key determinant of centromere identity and function, in a mechanism requiring active transcription of centromeric repeats, the DNA Damage Response (DDR) effector ATM and chromatin remodelers/histone chaperones. In the absence of p53 checkpoint, activated transcription of centromeric repeats and CENP-A delocalization do not occur and cells accumulate micronuclei indicative of genomic instability. In addition, activated transcription and loss of centromeres identity are features of permanently arrested senescent cells with persistent DDR activation. Together, these findings bring out cooperation between DDR effectors and loss of centromere integrity as a safeguard mechanism to prevent genomic instability in context of persistent DNA damage signalling.

Highlights

Centromeres are chromosomal domains essential for genomic stability
We report that murine centromeric transcripts accumulate upon DNA damage within a few hours, in a manner that is dependent on the DNA damage response (DDR) effector p53
Centromere architecture was assessed in single cells using immunofluorescence (IF) to follow CENP-A localization and DNA-FISH using probes specific for centromeric repeats termed minor satellites in the mouse

Summary

Introduction

Centromeres are chromosomal domains essential for genomic stability. We report here the remarkable transcriptional and epigenetic perturbations at murine centromeres in genotoxic stress conditions. We treated murine NIH/3T3 cells with a representative panel of genotoxic agents under conditions known to promote various types of DNA damage (Table S1) as revealed by accumulation of phosphorylated histone variant H2A.X (γH 2A.X) and stabilization of p53 (Figure S1A).

Results

Conclusion