Systematic proteomics of endogenous human cohesin reveals an interaction with diverse splicing factors and RNA binding proteins required for mitotic progression


The cohesin complex regulates sister chromatid cohesion, chromosome organization, gene expression, and DNA repair. Cohesin is a ring complex composed of four core subunits and seven regulatory subunits. In an effort to comprehensively identify additional cohesin-interacting proteins, we used gene editing to introduce a dual epitope tag into the endogenous allele of each of 11 known components of cohesin in cultured human cells and performed MS analyses on dual affinity purifications. In addition to reciprocally identifying all known components of cohesin, we found that cohesin interacts with a panoply of splicing factors and RNA-binding proteins (RBPs). These included diverse components of the U4/U6.U5 tri–small nuclear ribonucleoprotein (snRNP) complex and several splicing factors that are commonly mutated in cancer. The interaction between cohesin and splicing factors/RBPs was RNA and DNA independent, occurred in chromatin, was enhanced during mitosis, and required RAD21. Furthermore, cohesin-interacting splicing factors and RBPs followed the cohesin cycle and prophase pathway of cell cycle–regulated interactions with chromatin. Depletion of cohesin-interacting splicing factors and RBPs resulted in aberrant mitotic progression. These results provide a comprehensive view of the endogenous human cohesin interactome and identify splicing factors and RBPs as functionally significant cohesin-interacting proteins.

Journal of Biological Chemistry