Imaging the response to DNA damage in heterochromatin domains reveals core principles of heterochromatin maintenance

• Published in: Nature communications Vol. 12; no. 1; p. 2428
• Main Authors: Fortuny, Anna, Chansard, Audrey, Caron, Pierre, Chevallier, Odile, Leroy, Olivier, Renaud, Olivier, Polo, Sophie E.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 23.04.2021; Nature Publishing Group; Nature Portfolio
• Subjects: 14; 38; 631/1647/245; 631/337/100; 631/337/1427; Animals; Cell fate; Cell Line, Tumor; Chromatin; Chromatin Assembly and Disassembly - genetics; Damage; Deoxyribonucleic acid; DNA; DNA - genetics; DNA - metabolism; DNA Damage; DNA Repair; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; Gene silencing; Genomes; Genomic instability; Genotoxicity; Heterochromatin; Heterochromatin - genetics; Heterochromatin - radiation effects; Histone-Lysine N-Methyltransferase - genetics; Histone-Lysine N-Methyltransferase - metabolism; Histones; Histones - metabolism; Humanities and Social Sciences; Humans; Integrity; Life Sciences; Maintenance; Mammalian cells; MCF-7 Cells; Methylation; Methyltransferase; Mice; Molecular modelling; multidisciplinary; NIH 3T3 Cells; Real time; Science; Science (multidisciplinary); Stability; Tracking; Ultraviolet Rays
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-021-22575-5

Heterochromatin is a critical chromatin compartment, whose integrity governs genome stability and cell fate transitions. How heterochromatin features, including higher-order chromatin folding and histone modifications associated with transcriptional silencing, are maintained following a genotoxic stress challenge is unknown. Here, we establish a system for targeting UV damage to pericentric heterochromatin in mammalian cells and for tracking the heterochromatin response to UV in real time. We uncover profound heterochromatin compaction changes during repair, orchestrated by the UV damage sensor DDB2, which stimulates linker histone displacement from chromatin. Despite massive heterochromatin unfolding, heterochromatin-specific histone modifications and transcriptional silencing are maintained. We unveil a central role for the methyltransferase SETDB1 in the maintenance of heterochromatic histone marks after UV. SETDB1 coordinates histone methylation with new histone deposition in damaged heterochromatin, thus protecting cells from genome instability. Our data shed light on fundamental molecular mechanisms safeguarding higher-order chromatin integrity following DNA damage. The heterochromatin compartment is key for genome stability and cell fate transitions. Here, by tracking the heterochromatin response to UV damage in real time, the authors reveal how heterochromatin features are preserved following a genotoxic stress challenge.