Roberts syndrome: A deficit in acetylated cohesin leads to nucleolar dysfunction

All living organisms must go through cycles of replicating their genetic information and then dividing the copies between two new cells. This cyclical process, in cells from bacteria and human alike, requires a protein complex known as cohesin. Cohesin is a structural maintenance of chromosomes (SMC) complex. While bacteria have one form of this complex, yeast have several SMC complexes, and humans have at least a dozen cohesin complexes alone. Therefore the ancient structure and function of SMC complexes has been both conserved and specialized over the course of evolution. These complexes play roles in replication, repair, organization, and segregation of the genome. Mutations in the genes that encode cohesin and its regulatory factors are associated with developmental disorders such as Roberts syndrome, Cornelia de Lange syndrome, and cancer. In this review, we focus on how acetylation of cohesin contributes to its function. In Roberts syndrome, the lack of cohesin acetylation contributes to nucleolar defects and translational inhibition. An understanding of basic SMC complex function will be essential to unraveling the molecular etiology of human diseases associated with defective SMC function.