Studies of meiosis disclose distinct roles of cohesion in the core centromere and pericentromeric regions
During meiosis, a single round of genome duplication is followed by two sequential rounds of chromosome segregation. Through this process, a diploid parent cell generates gametes with a haploid set of chromosomes. A characteristic of meiotic chromosome segregation is a stepwise loss of sister chromatid cohesion along chromosomal arms and at centromeres. Whereas arm cohesion plays an important role in ensuring homologue disjunction at meiosis I, persisting cohesion at pericentromeric regions throughout meiosis I is essential for the faithful equational segregation of sisters in the following meiosis II, similar to mitosis. A widely conserved pericentromeric protein called shugoshin, which associates with protein phosphatase 2A (PP2A), plays a critical role in this protection of cohesin. Another key aspect of meiosis I is the establishment of monopolar attachment of sister kinetochores to spindle microtubules. Cohesion or physical linkage at the core centromeres, where kinetochores assemble, may conjoin sister kinetochores, leading to monopolar attachment. A meiosis-specific kinetochore factor such as fission yeast Moa1 or budding yeast monopolin contributes to this regulation. We propose that cohesion at the core centromere and pericentromeric regions plays distinct roles, especially in defining the orientation of kinetochores.
Keywordscohesin centromere meiosis kinetochore orientation shugoshin
casein kinase 1 δ/ɛ
heterochromatin protein 1
mitotic centromere-associated kinesin
mouse embryonic fibroblast
protein phosphatase 2A
structural maintenance of chromosome
We apologize to those researchers whose work was not cited or discussed owing to space limitations. This work was supported in part by a Special Coordination Funds for Promoting Science and Technology (to T.S.) and a Grant-in-Aid for Specially Promoted Research from the Ministry of Education, Culture, Sports, Science and Technology of Japan (to Y.W.).