STAG1 and STAG2 are critical components of the cohesin ring complex. However, their roles in regulating chromatin structure reconfigurations during the M-to-G1 transition remain unclear. In this study, we used ChIP-seq and fluorescence-activated cell sorting (FACS) to investigate the distinct loading kinetics of STAG1 and STAG2 in G1E-ER4 cells. We identified their binding sites across different stages of G1 and explored their impact on chromatin loop formation and compartmentalization. K-means clustering revealed three distinct clusters based on STAG1 accumulation speed: Cluster 1 (fastest), Cluster 2 (intermediate), and Cluster 3 (slowest). STAG2, in contrast, displayed consistently slower accumulation across all clusters. Faster accumulating clusters formed stronger chromatin loops, particularly within the 1M-2M range, while slower clusters exhibited weaker loop formation. Depletion of STAG1 or STAG2 revealed minimal cross-interference, as the loss of one did not significantly impact the binding strength or sites of the other. Moreover, aggregate peak analysis (APA) showed that STAG2 depletion had little effect on CTCF-mediated loop formation in early G1 but had a more pronounced impact in late G1. These findings suggest that STAG1 and STAG2 play distinct roles in regulating chromatin architecture during G1, particularly in chromatin loop formation.
 

cohesin,STAG1,STAG2,dynamic,mitosis