Pilot multi-level review

Loop Extrusion Model

Scientists study how proteins gather DNA into loops by comparing computer models, cell experiments and movies of purified molecules.

Reading level

Graduate / Professional Undergraduate Lay Public

The idea: gather DNA into a growing loop

Imagine gathering more of a long ribbon into a loop. Loop extrusion is a similar proposal for DNA and a protein complex. Computer models using this rule reproduced some patterns in DNA contact maps. That agreement makes the idea useful, but a computer model is not a recording of a cell. [1]

One test removes the protein

In engineered human cancer cells grown in the laboratory, researchers removed a component of cohesin. The DNA contact map lost its loop-domain patterns, while another organizational pattern remained. This shows that cohesin mattered for those domains in those cells. The map combines many cells; it does not show every DNA loop moving. [2]

Another test watches molecules

Researchers also watched loops grow on DNA with purified human proteins and ATP, a chemical energy source. A protein called CTCF sometimes stopped the growing loop. Whether it stopped the loop depended on its direction and how stretched the DNA was. This is direct evidence in a simplified laboratory system, not a movie of an entire nucleus. [3]

A newer experiment in living human cells — 12 October 2026

A newer study tracked pairs of DNA labels at three chromosome regions in living human cells. The labels came close and separated again; removing cohesin changed that behavior. This supports changing, cohesin-dependent organization in those cells. The labels show selected DNA positions, not a complete movie of a protein pulling every DNA loop. Sabaté et al. (2025).

This addition uses primary studies. Access depth and claim limits are recorded with each added reference; it is a dated literature appraisal, not independent experimental replication.

Primary studies behind this guide

  1. Fudenberg et al. (2016), Cell Reports 15:2038–2049. Formation of Chromosomal Domains by Loop Extrusion. DOI: 10.1016/j.celrep.2016.04.085. Primary research.
  2. Rao et al. (2017), Cell 171:305–320.e24. Cohesin Loss Eliminates All Loop Domains. DOI: 10.1016/j.cell.2017.09.026. Primary research.
  3. Davidson et al. (2023), Nature 616:822–827. CTCF is a DNA-tension-dependent barrier to cohesin-mediated loop extrusion. DOI: 10.1038/s41586-023-05961-5. Primary research.
  4. Sabaté T, Lelandais B, Robert MC, et al. (2025). Uniform dynamics of cohesin-mediated loop extrusion in living human cells. Nature Genetics 57:3152–3164. DOI: 10.1038/s41588-025-02406-9. Primary research.

    Independent update access: Consensus fetched primary abstract and Scite selected main-text passages, including study design and initial Results; not every supplementary analysis inspected. Primary source.

Scientific text and the identity and fit of the cited studies were checked on 3 October 2026. This guide covers the experiments described here; it is not an exhaustive literature review. See the audit record for access limits and remaining work.