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Title: A single double-strand break system reveals repair dynamics and mechanisms in heterochromatin and euchromatin

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.
Authors:
 [1] ;  [2] ;  [3] ;  [1] ;  [1] ;  [3] ;  [2] ;  [4] ;  [5]
  1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  2. Yale School of Medicine, New Haven, CT (United States)
  3. Netherlands Cancer Inst., Amsterdam (Netherlands)
  4. Georgetown Univ. Medical Center, Washington, DC (United States)
  5. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States)
Publication Date:
Grant/Contract Number:
AC02-05CH11231
Type:
Accepted Manuscript
Journal Name:
Genes and Development
Additional Journal Information:
Journal Volume: 30; Journal Issue: 14; Journal ID: ISSN 0890-9369
Publisher:
Cold Springs Harbor Press
Research Org:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org:
National Institutes of Health (NIH); USDOE
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES
OSTI Identifier:
1379517
Alternate Identifier(s):
OSTI ID: 1379518