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Chromosome structure in Drosophila is determined by boundary pairing not loop extrusion
- Source :
- eLife, Vol 13 (2024)
- Publication Year :
- 2024
- Publisher :
- eLife Sciences Publications Ltd, 2024.
-
Abstract
- Two different models have been proposed to explain how the endpoints of chromatin looped domains (‘TADs’) in eukaryotic chromosomes are determined. In the first, a cohesin complex extrudes a loop until it encounters a boundary element roadblock, generating a stem-loop. In this model, boundaries are functionally autonomous: they have an intrinsic ability to halt the movement of incoming cohesin complexes that is independent of the properties of neighboring boundaries. In the second, loops are generated by boundary:boundary pairing. In this model, boundaries are functionally non-autonomous, and their ability to form a loop depends upon how well they match with their neighbors. Moreover, unlike the loop-extrusion model, pairing interactions can generate both stem-loops and circle-loops. We have used a combination of MicroC to analyze how TADs are organized, and experimental manipulations of the even skipped TAD boundary, homie, to test the predictions of the ‘loop-extrusion’ and the ‘boundary-pairing’ models. Our findings are incompatible with the loop-extrusion model, and instead suggest that the endpoints of TADs in flies are determined by a mechanism in which boundary elements physically pair with their partners, either head-to-head or head-to-tail, with varying degrees of specificity. Although our experiments do not address how partners find each other, the mechanism is unlikely to require loop extrusion.
Details
- Language :
- English
- ISSN :
- 2050084X
- Volume :
- 13
- Database :
- Directory of Open Access Journals
- Journal :
- eLife
- Publication Type :
- Academic Journal
- Accession number :
- edsdoj.69f54650950e47cea510ecc8aa1663b4
- Document Type :
- article
- Full Text :
- https://doi.org/10.7554/eLife.94070