93 / 2024-10-21 21:04:30

Dynamic Differences in STAG1 and STAG2 Chromatin Loading During G1 Phase and Their Regulation of Chromatin Architecture

cohesin,STAG1,STAG2,dynamic,mitosis

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.