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Updated: Jul 6, 2026
07:59
Molecular Entanglement and Electrospinnability of Biopolymers
Published on: September 3, 2014
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The physical chemistry of interphase loop extrusion.
Maxime M C Tortora1, Geoffrey Fudenberg1
1Department of Quantitative and Computational Biology, University of Southern California, Los Angeles, CA 90007, USA.
Cell Genomics
|December 11, 2025
Summary
Cohesin
Area of Science:
- Molecular Biology
- Genetics
- Biophysics
Background:
- Cohesin complex is crucial for genome organization through loop extrusion.
- Accessory proteins dynamically regulate cohesin's loop-extrusion activity.
- Disruption of these regulators impacts chromosome morphology and dynamics.
Purpose of the Study:
- To develop a quantitative theory for cohesin regulation and its effect on genome folding.
- To model the interplay between cohesin regulators and loop extrusion dynamics.
- To link molecular-scale cohesin dynamics to genome-wide organization.
Main Methods:
- Derivation of a chemical-reaction network model for loop extrusion regulation.
- Development of a "bursty extrusion model" based on first principles.
- Incorporation of the model into polymer simulations.
Main Results:
- The model distinguishes the roles of regulatory proteins and their transient binding.
- It reveals how regulator exchange leads to intermittent motor activity.
- Simulations show that variations in regulatory protein abundance alter chromatin architecture across scales.
Conclusions:
- The bursty extrusion model quantitatively explains cohesin regulation.
- It bridges the gap between molecular dynamics and large-scale genome organization.
- Findings are supported by in vivo and in vitro experimental data.
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