Molecular Cell· 2025Q1
A unified model for cohesin function in sister chromatid cohesion and chromatin loop formation
- 40citations
- Q1SCImago
- 2025year
Short summary
Cohesin forms chromatin loops via sequential topological capture of two DNAs, similar to sister chromatid cohesion, challenging the prevailing loop extrusion model.
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Key points
- Cohesin's role in sister chromatid cohesion and chromatin loop formation may share a common mechanism: sequential topological capture of two DNAs.
- This 'loop capture' model challenges the established 'loop extrusion' mechanism for in vivo chromatin loop formation.
- The proposed model is extended to encompass other structural maintenance of chromosomes (SMC) family members like condensin and bacterial SMC complexes.
AI-generated from the title and abstract; the full text is not read.
Abstract
The ring-shaped cohesin complex topologically entraps two DNAs to establish sister chromatid cohesion. Cohesin also shapes the interphase chromatin landscape by forming DNA loops, which it is thought to achieve using an in vitro-observed loop extrusion mechanism. However, recent studies revealed that loop-extrusion-deficient cohesin retains its ability to form chromatin loops, suggesting a divergence of in vitro and in vivo loop formation. Instead of loop extrusion, we examine whether cohesin forms chromatin loops by a mechanism akin to sister chromatid cohesion establishment: sequential topological capture of two DNAs. We explore similarities and differences between the "loop capture" and the "loop extrusion" model, how they compare at explaining experimental observations, and how future approaches can delineate their possible respective contributions. We extend our DNA-DNA capture model for cohesin function to related structural maintenance of chromosomes (SMC) family members, condensin, the Smc5-Smc6 complex, and bacterial SMC complexes.
The authors' abstract, as published at the source. Molecular Cell, 2025 · DOI ↗
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Field: Molecular Biology
Molecular BiologyBiochemistry, Genetics and Molecular Biology