Dynamic Organization of Chromatin Domains Revealed by Super-Resolution Live-Cell Imaging

Mol Cell. 2017 Jul 20;67(2):282-293.e7. doi: 10.1016/j.molcel.2017.06.018. Epub 2017 Jul 14.

Abstract

The eukaryotic genome is organized within cells as chromatin. For proper information output, higher-order chromatin structures can be regulated dynamically. How such structures form and behave in various cellular processes remains unclear. Here, by combining super-resolution imaging (photoactivated localization microscopy [PALM]) and single-nucleosome tracking, we developed a nuclear imaging system to visualize the higher-order structures along with their dynamics in live mammalian cells. We demonstrated that nucleosomes form compact domains with a peak diameter of ∼160 nm and move coherently in live cells. The heterochromatin-rich regions showed more domains and less movement. With cell differentiation, the domains became more apparent, with reduced dynamics. Furthermore, various perturbation experiments indicated that they are organized by a combination of factors, including cohesin and nucleosome-nucleosome interactions. Notably, we observed the domains during mitosis, suggesting that they act as building blocks of chromosomes and may serve as information units throughout the cell cycle.

Keywords: PALM; chromatin; chromatin domain; chromatin dynamics; chromosome; single-nucleosome tracking.

Publication types

  • Video-Audio Media

MeSH terms

  • Animals
  • Cell Cycle Proteins / metabolism
  • Cell Differentiation
  • Chromatin Assembly and Disassembly*
  • Chromosomal Proteins, Non-Histone / metabolism
  • Chromosomes, Human
  • HCT116 Cells
  • HeLa Cells
  • Heterochromatin / chemistry
  • Heterochromatin / metabolism*
  • Humans
  • Mice
  • Microscopy, Video / methods*
  • Mitosis*
  • Motion
  • Nucleic Acid Conformation
  • Nucleosomes / chemistry
  • Nucleosomes / metabolism*
  • Protein Conformation
  • RNA Interference
  • Structure-Activity Relationship
  • Time Factors
  • Transcription, Genetic
  • Transfection

Substances

  • Cell Cycle Proteins
  • Chromosomal Proteins, Non-Histone
  • Heterochromatin
  • Nucleosomes
  • cohesins