Processive DNA synthesis is associated with localized decompaction of constitutive heterochromatin at the sites of DNA replication and repair

Nucleus. 2019 Dec;10(1):231-253. doi: 10.1080/19491034.2019.1688932.


Constitutive heterochromatin is considered as a functionally inert genome compartment, important for its architecture and stability. How such stable structure is maintained is not well understood. Here, we apply four different visualization schemes to label it and investigate its dynamics during DNA replication and repair. We show that replisomes assemble over the heterochromatin in a temporally ordered manner. Furthermore, heterochromatin undergoes transient decompaction locally at the active sites of DNA synthesis. Using selective laser microirradiation conditions that lead to damage repaired via processive DNA synthesis, we measured similarly local decompaction of heterochromatin. In both cases, we could not observe large-scale movement of heterochromatin to the domain surface. Instead, the processive DNA synthesis machinery assembled at the replication/repair sites. Altogether, our data are compatible with a progression of DNA replication/repair along the chromatin in a dynamic mode with localized and transient decompaction that does not globally remodels the whole heterochromatin compartment.

Keywords: DNA repair; DNA replication; PCNA; chromatin compaction; chromocenters; genome architecture; pericentromeric heterochromatin; processive DNA synthesis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cells, Cultured
  • DNA / biosynthesis*
  • DNA / chemistry
  • DNA Repair*
  • DNA Replication*
  • HeLa Cells
  • Heterochromatin / chemistry
  • Heterochromatin / metabolism*
  • Humans
  • Mice


  • Heterochromatin
  • DNA

Grants and funding

This work was supported in part by grants of the Deutsche Forschungsgemeinschaft [DFG CA198/9-2 and SFB 1361/TP 6 to MCC; SFB 646/TP B10 to HL] and the Bundesministerium für Bildung und Forschung [BMBF 02NUK036D to AR].