title: Repositioning of aurora B promoted by chiasmata ensures sister chromatid mono-orientation in meiosis I.
abstract: During meiosis I, kinetochores of sister chromatids are juxtaposed or fused and mono-orient, while homologous chromosomes that are paired by chiasmata (bivalents) have to biorient. In the absence of chiasmata, biorientation of sister chromatids (univalents), which carries a risk of aneuploidy, has been occasionally detected in several species, including humans. We show in fission yeast that biorientation of fused sister kinetochores predominates during early prometaphase I. Without chiasmata, this undesirable biorientation of univalents persists and eventually evades the spindle assembly checkpoint, provoking abnormal anaphase. When univalents are connected by chiasmata or by an artificial tether, this erroneous attachment is converted to monopolar attachment and stabilized. This stabilization is apparently achieved by a chromosome configuration that brings kinetochores to the outer edge of the bivalent, while bringing Aurora B, a destabilizer of kinetochore-microtubule attachment, inward. Our results elucidate how chiasmata favor biorientation of bivalents over that of univalents at meiosis I.
authors.affiliation: Laboratory of Chromosome Dynamics, Institute of Molecular and Cellular Biosciences; Promotion of Independence for Young Investigators, University of Tokyo, Yayoi, Tokyo 113-0032, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Sakuno
authors.forename: Koichi
authors.initials: K
authors.lastname: Tanaka
authors.forename: Silke
authors.initials: S
authors.lastname: Hauf
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Watanabe
mesh_terms: D064127:Aurora Kinases; D020090:Chromosome Segregation; D018386:Kinetochores / Q000201:enzymology; D008540:Meiosis; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D012568:Schizosaccharomyces / Q000201:enzymology* / Q000235:genetics; D029702:Schizosaccharomyces pombe Proteins / Q000235:genetics / Q000378:metabolism*; D012854:Sister Chromatid Exchange
chemical_list: D029702:Schizosaccharomyces pombe Proteins; D064127:Aurora Kinases; D017346:Protein Serine-Threonine Kinases; C576962:ark1 protein, S pombe