title: Age-related decrease of meiotic cohesins in human oocytes.
abstract: Aneuploidy in fetal chromosomes is one of the causes of pregnancy loss and of congenital birth defects. It is known that the frequency of oocyte aneuploidy increases with the human maternal age. Recent data have highlighted the contribution of cohesin complexes in the correct segregation of meiotic chromosomes. In mammalian oocytes, cohesion is established during the fetal stages and meiosis-specific cohesin subunits are not replenished after birth, raising the possibility that the long meiotic arrest of oocytes facilitates a deterioration of cohesion that leads to age-related increases in aneuploidy. We here examined the cohesin levels in dictyate oocytes from different age groups of humans and mice by immunofluorescence analyses of ovarian sections. The meiosis-specific cohesin subunits, REC8 and SMC1B, were found to be decreased in women aged 40 and over compared with those aged around 20 years (P<0.01). Age-related decreases in meiotic cohesins were also evident in mice. Interestingly, SMC1A, the mitotic counterpart of SMC1B, was substantially detectable in human oocytes, but little expressed in mice. Further, the amount of mitotic cohesins of mice slightly increased with age. These results suggest that, mitotic and meiotic cohesins may operate in a coordinated way to maintain cohesions over a sustained period in humans and that age-related decreases in meiotic cohesin subunits impair sister chromatid cohesion leading to increased segregation errors.
authors.affiliation: Division of Molecular Genetics, Institute for Comprehensive Medical Science, Fujita Health University, Toyoake, Aichi, Japan.
authors.forename: Makiko
authors.initials: M
authors.lastname: Tsutsumi
authors.affiliation: Division of Molecular Genetics, Institute for Comprehensive Medical Science, Fujita Health University, Toyoake, Aichi, Japan.
authors.forename: Reiko
authors.initials: R
authors.lastname: Fujiwara
authors.affiliation: Department of Obstetrics and Gynecology, Fujita Health University, Toyoake, Aichi, Japan.
authors.forename: Haruki
authors.initials: H
authors.lastname: Nishizawa
authors.affiliation: Division of Molecular Genetics, Institute for Comprehensive Medical Science, Fujita Health University, Toyoake, Aichi, Japan; Department of Obstetrics and Gynecology, Fujita Health University, Toyoake, Aichi, Japan.
authors.forename: Mayuko
authors.initials: M
authors.lastname: Ito
authors.affiliation: Department of Anatomy and Cell Biology, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kogo
authors.affiliation: Division of Molecular Genetics, Institute for Comprehensive Medical Science, Fujita Health University, Toyoake, Aichi, Japan.
authors.forename: Hidehito
authors.initials: H
authors.lastname: Inagaki
authors.affiliation: Division of Molecular Genetics, Institute for Comprehensive Medical Science, Fujita Health University, Toyoake, Aichi, Japan.
authors.forename: Tamae
authors.initials: T
authors.lastname: Ohye
authors.affiliation: Division of Molecular Genetics, Institute for Comprehensive Medical Science, Fujita Health University, Toyoake, Aichi, Japan.
authors.forename: Takema
authors.initials: T
authors.lastname: Kato
authors.affiliation: Department of Obstetrics and Gynecology, Fujita Health University, Toyoake, Aichi, Japan.
authors.forename: Takuma
authors.initials: T
authors.lastname: Fujii
authors.affiliation: Division of Molecular Genetics, Institute for Comprehensive Medical Science, Fujita Health University, Toyoake, Aichi, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Kurahashi
mesh_terms: D000328:Adult; D000367:Age Factors; D000375:Aging / Q000378:metabolism*; D000782:Aneuploidy; D000818:Animals; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism*; D005260:Female; D006801:Humans; D008540:Meiosis / Q000502:physiology*; D051379:Mice; D008875:Middle Aged; D009865:Oocytes / Q000378:metabolism*; D055815:Young Adult; D000097722:Cohesins
chemical_list: D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone; D000097722:Cohesins