Chromosomal localization of cohesin is differentially regulated by WIZ, WAPL, and G9a

Background The cohesin complex is essential for proper chromosome structure and gene expression. Defects in cohesin subunits and regulators cause changes in cohesin complex dynamics and thereby alter three-dimensional genome organization. However, the molecular mechanisms that drive cohesin localization and function remain poorly understood. Results In this study, we observe that loss of WIZ causes changes to cohesin localization that are distinct from loss of the known WIZ binding partner G9a. Whereas loss of WIZ uniformly increases cohesin levels on chromatin at known binding sites and leads to new, ectopic cohesin binding sites, loss of G9a does not. Ectopic cohesin binding on chromatin after the loss of WIZ occurs at regions that are enriched for activating histone modifications and transcription factors motifs. Furthermore, loss of WIZ causes changes in cohesin localization that are distinct from those observed by loss of WAPL, the canonical cohesin unloading factor. Conclusions The evidence presented here suggests that WIZ can function independently from its previously identified role with G9a and GLP in heterochromatin formation. Furthermore, while WIZ limits the levels and localization pattern of cohesin across the genome, it appears to function independently of WAPL-mediated cohesin unloading.

Automated summary

The study found that loss of WIZ leads to changes in cohesin localization on chromatin, distinct from loss of G9a and canonical cohesin unloading factor WAPL. Ectopic cohesin binding sites were observed after the loss of WIZ, enriched for activating histone modifications and transcription factor motifs. WIZ appears to function independently of its previously identified role in heterochromatin formation.