title: Cohesion promotes nucleolar structure and function.
abstract: The cohesin complex contributes to ribosome function, although the molecular mechanisms involved are unclear. Compromised cohesin function is associated with a class of diseases known as cohesinopathies. One cohesinopathy, Roberts syndrome (RBS), occurs when a mutation reduces acetylation of the cohesin Smc3 subunit. Mutation of the cohesin acetyltransferase is associated with impaired rRNA production, ribosome biogenesis, and protein synthesis in yeast and human cells. Cohesin binding to the ribosomal DNA (rDNA) is evolutionarily conserved from bacteria to human cells. We report that the RBS mutation in yeast (eco1-W216G) exhibits a disorganized nucleolus and reduced looping at the rDNA. RNA polymerase I occupancy of the genes remains normal, suggesting that recruitment is not impaired. Impaired rRNA production in the RBS mutant coincides with slower rRNA cleavage. In addition to the RBS mutation, mutations in any subunit of the cohesin ring are associated with defects in ribosome biogenesis. Depletion or artificial destruction of cohesion in a single cell cycle is associated with loss of nucleolar integrity, demonstrating that the defects at the rDNA can be directly attributed to loss of cohesion. Our results strongly suggest that organization of the rDNA provided by cohesion is critical for formation and function of the nucleolus.
authors.affiliation: Stowers Institute for Medical Research, Kansas City, MO 64110 Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, KS 66160 Department of Microbiology, Immunology and Cancer Biology, University of Virginia School of Medicine, Charlottesville, VA 22908.
authors.forename: Bethany
authors.initials: B
authors.lastname: Harris
authors.forename: Tania
authors.initials: T
authors.lastname: Bose
authors.forename: Kenneth K
authors.initials: KK
authors.lastname: Lee
authors.forename: Fei
authors.initials: F
authors.lastname: Wang
authors.forename: Shuai
authors.initials: S
authors.lastname: Lu
authors.forename: Rhonda Trimble
authors.initials: RT
authors.lastname: Ross
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhang
authors.forename: Sarah L
authors.initials: SL
authors.lastname: French
authors.forename: Ann L
authors.initials: AL
authors.lastname: Beyer
authors.forename: Brian D
authors.initials: BD
authors.lastname: Slaughter
authors.forename: Jay R
authors.initials: JR
authors.lastname: Unruh
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Gerton
mesh_terms: D000123:Acetyltransferases / Q000235:genetics*; D002453:Cell Cycle / Q000235:genetics; D018797:Cell Cycle Proteins / Q000235:genetics*; D002843:Chromatin / Q000235:genetics; D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics*; D019465:Craniofacial Abnormalities / Q000235:genetics; D004275:DNA, Ribosomal / Q000235:genetics*; D004480:Ectromelia / Q000235:genetics; D006972:Hypertelorism / Q000235:genetics; D046529:Microscopy, Electron, Transmission; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism; D009697:Nucleolus Organizer Region / Q000235:genetics; D012318:RNA Polymerase I / Q000235:genetics; D012335:RNA, Ribosomal / Q000096:biosynthesis / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics*; D000097722:Cohesins
chemical_list: D000123:Acetyltransferases; D018797:Cell Cycle Proteins; D002843:Chromatin; D002868:Chromosomal Proteins, Non-Histone; D004275:DNA, Ribosomal; D009687:Nuclear Proteins; D012318:RNA Polymerase I; D012335:RNA, Ribosomal; D029701:Saccharomyces cerevisiae Proteins; D000097722:Cohesins; C118076:ECO1 protein, S cerevisiae