TY - JOUR
T1 - A single double-strand break system reveals repair dynamics and mechanisms in heterochromatin and euchromatin
AU - Janssen, Aniek
AU - Breuer, Gregory A
AU - Brinkman, Eva K
AU - van der Meulen, Annelot I
AU - Borden, Sean V
AU - van Steensel, Bas
AU - Bindra, Ranjit S
AU - LaRocque, Jeannine R
AU - Karpen, Gary H
N1 - © 2016 Janssen et al.; Published by Cold Spring Harbor Laboratory Press.
PY - 2016/7/15
Y1 - 2016/7/15
N2 - Repair of DNA double-strand breaks (DSBs) must be properly orchestrated in diverse chromatin regions to maintain genome stability. The choice between two main DSB repair pathways, nonhomologous end-joining (NHEJ) and homologous recombination (HR), is regulated by the cell cycle as well as chromatin context.Pericentromeric heterochromatin forms a distinct nuclear domain that is enriched for repetitive DNA sequences that pose significant challenges for genome stability. Heterochromatic DSBs display specialized temporal and spatial dynamics that differ from euchromatic DSBs. Although HR is thought to be the main pathway used to repair heterochromatic DSBs, direct tests of this hypothesis are lacking. Here, we developed an in vivo single DSB system for both heterochromatic and euchromatic loci in Drosophila melanogaster Live imaging of single DSBs in larval imaginal discs recapitulates the spatio-temporal dynamics observed for irradiation (IR)-induced breaks in cell culture. Importantly, live imaging and sequence analysis of repair products reveal that DSBs in euchromatin and heterochromatin are repaired with similar kinetics, employ both NHEJ and HR, and can use homologous chromosomes as an HR template. This direct analysis reveals important insights into heterochromatin DSB repair in animal tissues and provides a foundation for further explorations of repair mechanisms in different chromatin domains.
AB - Repair of DNA double-strand breaks (DSBs) must be properly orchestrated in diverse chromatin regions to maintain genome stability. The choice between two main DSB repair pathways, nonhomologous end-joining (NHEJ) and homologous recombination (HR), is regulated by the cell cycle as well as chromatin context.Pericentromeric heterochromatin forms a distinct nuclear domain that is enriched for repetitive DNA sequences that pose significant challenges for genome stability. Heterochromatic DSBs display specialized temporal and spatial dynamics that differ from euchromatic DSBs. Although HR is thought to be the main pathway used to repair heterochromatic DSBs, direct tests of this hypothesis are lacking. Here, we developed an in vivo single DSB system for both heterochromatic and euchromatic loci in Drosophila melanogaster Live imaging of single DSBs in larval imaginal discs recapitulates the spatio-temporal dynamics observed for irradiation (IR)-induced breaks in cell culture. Importantly, live imaging and sequence analysis of repair products reveal that DSBs in euchromatin and heterochromatin are repaired with similar kinetics, employ both NHEJ and HR, and can use homologous chromosomes as an HR template. This direct analysis reveals important insights into heterochromatin DSB repair in animal tissues and provides a foundation for further explorations of repair mechanisms in different chromatin domains.
KW - Animals
KW - Cytological Techniques
KW - DNA Breaks, Double-Stranded
KW - DNA Repair/physiology
KW - Drosophila melanogaster/cytology
KW - Euchromatin/genetics
KW - Heterochromatin/genetics
KW - Homologous Recombination
KW - Larva
U2 - 10.1101/gad.283028.116
DO - 10.1101/gad.283028.116
M3 - Article
C2 - 27474442
SN - 0890-9369
VL - 30
SP - 1645
EP - 1657
JO - Genes and Development
JF - Genes and Development
IS - 14
ER -