@article {Misulovin170829, author = {Ziva Misulovin and Michelle Pherson and Maria Gause and Kathie Mihindukulasuriya and Dale Dorsett}, title = {Roles of the Brca2 and Wapl complexes with Pds5 in sister chromatid cohesion, cohesin localization, and gene expression}, elocation-id = {170829}, year = {2017}, doi = {10.1101/170829}, publisher = {Cold Spring Harbor Laboratory}, abstract = {The cohesin complex topologically encircles chromosomes and mediates sister chromatid cohesion to ensure accurate chromosome segregation upon cell division. Cohesin also participates in DNA repair and gene transcription. The Nipped-B protein loads cohesin onto chromosomes and the Pds5-Wapl complex removes cohesin. Pds5 is also essential for sister chromatid cohesion, indicating that it has functions beyond cohesin removal. The Brca2 DNA repair protein interacts with Pds5 but the roles of this complex are poorly understood. Here we show that Brca2 opposes Pds5 function in sister chromatid cohesion but has similar effects on gene expression. Pds5 facilitates SA cohesin subunit association with DNA replication origins and Brca2 inhibits SA binding, implying that SA levels at origins govern sister chromatid cohesion. Cohesin binding is maximal at replication origins and extends outward to occupy active genes and regulatory sequences. Pds5 and Wapl, but not Brca2, limit the distance that cohesin extends from origins, thereby determining which active genes bind cohesin. We posit that DNA replication pushes cohesin along chromosomes, and that the Pds5-Wapl complex unloads cohesin at replication forks to control the size of cohesin domains. In contrast to their opposing roles in chromatid cohesion, Pds5 and Brca2 have similar effects on gene expression. These effects overlap those of Nipped-B, cohesin and Wapl, indicating that Pds5 and Brca2 modify cohesin dynamics and function at active genes. These findings demonstrate that Brca2 regulates sister chromatid cohesion and gene expression in addition to its canonical role in DNA repair and expand the known functions of accessory proteins in cohesin function.Author summary The cohesin protein complex has multiple functions in eukaryotic cells. It ensures that when a cell divides, the two daughter cells receive the correct number of chromosomes. It does this by holding together the sister chromatids that are formed when chromosomes are duplicated by DNA replication. Cohesin also helps repair damaged DNA, and to regulate genes important for growth and development. Even minor deficiencies in some proteins that regulate cohesin cause significant birth defects in humans. Here we investigated in Drosophila how three proteins, Pds5, Wapl and Brca2, determine where cohesin binds to chromosomes, control cohesin{\textquoteright}s ability to hold sister chromatids together, and to regulate gene expression. We find that Pds5 and Wapl work together, likely during DNA replication, to determine which genes bind cohesin by controlling how far cohesin spreads out along chromosomes. Pds5 is required for cohesin to hold sister chromatids together, and Brca2 counteracts this function. In contrast to the opposing roles in sister chromatid cohesion, Pds5 and Brca2 work together to facilitate control of gene expression by cohesin. Brca2 plays a critical role in DNA repair, and these studies expand the known roles for Brca2 by showing that it also regulates sister chromatid cohesion and gene expression. BRCA2 mutations in humans increase susceptibility to breast and ovarian cancer, and these findings raise the possibility that changes in chromosome segregation or gene expression might contribute to the increased cancer risk associated with these mutations.}, URL = {https://www.biorxiv.org/content/early/2017/07/31/170829}, eprint = {https://www.biorxiv.org/content/early/2017/07/31/170829.full.pdf}, journal = {bioRxiv} }