How epigenome drives chromatin folding and dynamics, insights from efficient coarse-grained models of chromosomes

PLoS Comput Biol. 2018 May 29;14(5):e1006159. doi: 10.1371/journal.pcbi.1006159. eCollection 2018 May.

Abstract

The 3D organization of chromosomes is crucial for regulating gene expression and cell function. Many experimental and polymer modeling efforts are dedicated to deciphering the mechanistic principles behind chromosome folding. Chromosomes are long and densely packed-topologically constrained-polymers. The main challenges are therefore to develop adequate models and simulation methods to investigate properly the multi spatio-temporal scales of such macromolecules. Here, we proposed a generic strategy to develop efficient coarse-grained models for self-avoiding polymers on a lattice. Accounting accurately for the polymer entanglement length and the volumic density, we show that our simulation scheme not only captures the steady-state structural and dynamical properties of the system but also tracks the same dynamics at different coarse-graining. This strategy allows a strong power-law gain in numerical efficiency and offers a systematic way to define reliable coarse-grained null models for chromosomes and to go beyond the current limitations by studying long chromosomes during an extended time period with good statistics. We use our formalism to investigate in details the time evolution of the 3D organization of chromosome 3R (20 Mbp) in drosophila during one cell cycle (20 hours). We show that a combination of our coarse-graining strategy with a one-parameter block copolymer model integrating epigenomic-driven interactions quantitatively reproduce experimental data at the chromosome-scale and predict that chromatin motion is very dynamic during the cell cycle.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Chromatin Assembly and Disassembly* / genetics
  • Chromatin Assembly and Disassembly* / physiology
  • Chromatin* / chemistry
  • Chromatin* / genetics
  • Chromatin* / metabolism
  • Chromosomes, Insect / chemistry
  • Chromosomes, Insect / genetics
  • Chromosomes, Insect / metabolism
  • Computational Biology
  • Drosophila / genetics
  • Epigenesis, Genetic* / genetics
  • Epigenesis, Genetic* / physiology
  • Epigenomics
  • Models, Genetic*
  • Molecular Dynamics Simulation

Substances

  • Chromatin

Grants and funding

This research is supported by Agence Nationale de la Recherche (ANR-15-CE12-0006 EpiDevoMath), Fondation pour la Recherche Medicale (DEI20151234396), Centre national de la recherche scientifique (CNRS). We acknowledge computational resources from CIMENT infrastructure (supported by the Rhone-Alpes region, Grant CPER07 13 CIRA). The funders had no role in study design, data collection, and analysis, decision to publish, or preparation of the manuscript.