PT  - JOURNAL ARTICLE
AU  - Gil, Dácil Alonso
AU  - Cuadrado, Ana
AU  - Giménez-Llorente, Daniel
AU  - Rodríguez-Corsino, Miriam
AU  - Losada, Ana
TI  - Different NIPBL requirements of cohesin-STAG1 and cohesin-STAG2
AID  - 10.1101/2022.11.29.518367
DP  - 2022 Jan 01
TA  - bioRxiv
PG  - 2022.11.29.518367
4099  - http://biorxiv.org/content/early/2022/11/29/2022.11.29.518367.short
4100  - http://biorxiv.org/content/early/2022/11/29/2022.11.29.518367.full
AB  - Cohesin organizes the genome through the formation of chromatin loops. NIPBL activates cohesin’s ATPase and is essential for loop extrusion, but its requirement for cohesin loading is currently unclear. Here we have examined the effect of reducing NIPBL levels on the behavior of the two cohesin variants carrying STAG1 or STAG2 by combining a flow cytometry assay to measure chromatin-bound cohesin with analyses of its genome-wide distribution and genome contacts. We show that NIPBL depletion results in increased cohesin-STAG1 on chromatin that further accumulates at CTCF positions while cohesin-STAG2 diminishes genome-wide. Our data support a model in which NIPBL is not required for initial association of cohesin with chromatin but it is for loop extrusion, which in turn facilitates stabilization of cohesin-STAG2 at CTCF positions after being loaded elsewhere. In contrast, cohesin-STAG1 is loaded and stabilized at CTCF sites even under low NIPBL levels, but genome folding is severely impaired.Competing Interest StatementThe authors have declared no competing interest.