ESCO1 and CTCF enable formation of long chromatin loops by protecting cohesin-STAG1 from WAPL

The human genome folds to create thousands of loops connecting sites that are bound by the insulator protein CTCF and the ring-shaped cohesin complex. It is thought that most of these loops emerge through a process whereby cohesin extrudes chromatin, forming an initially small loop that grows larger and larger until the loop's expansion is arrested by CTCF. Cohesin rings comprise four proteins: SMC1, SMC3, SCC1, and, in higher eukaryotes, either STAG1 or STAG2. We explore differential roles of especially STAG1, STAG2 and ESCO1 proteins in chromatin organization. Overall design: We combine Hi-C and ChIP-Seq data with FRAP and physical simulations to dissect the roles of these two forms of cohesin - STAG1 and STAG2 - in G1 phase.