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 we 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 U... More
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 we 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 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.
