title: Metaphase I arrest in LT/Sv mouse oocytes involves the spindle assembly checkpoint.
abstract: During meiotic maturation, the majority of oocytes from LT/Sv mice arrest at metaphase I. However, anaphase may be induced through parthenogenetic activation. If this happens within the ovary, it often results in the development of ovarian teratomas. Here, we show that the induction of first meiotic anaphase in LT/Sv oocytes results in incorrect chromosome segregation. In search of the molecular basis of this complex phenotype, we analyzed the localization/destruction of cohesins, as well as the function of the components of the spindle assembly checkpoint (SAC). Both localization and removal of meiotic cohesin REC8 from chromosomes are unperturbed. In contrast, there is prolonged localization of SAC proteins BUB1 and MAD2L1 (MAD2) at the metaphase I kinetochores in mutant oocytes compared with the wild-type. Interfering with BUB1 function through expression of a dominant-negative mutant protein resulted in the increase of the number of LT/Sv oocytes completing the first meiosis, which indicates SAC involvement in metaphase I arrest. These data show for the first time that there is a direct link between the SAC function and the heritable meiotic incompetence of a mammalian oocyte.
authors.affiliation: Department of Embryology, Institute of Zoology, Faculty of Biology, University of Warsaw, 02-096 Warsaw, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Hupalowska
authors.forename: Ilona
authors.initials: I
authors.lastname: Kalaszczynska
authors.forename: Steffen
authors.initials: S
authors.lastname: Hoffmann
authors.forename: Chizuko
authors.initials: C
authors.lastname: Tsurumi
authors.forename: Jacek Z
authors.initials: JZ
authors.lastname: Kubiak
authors.forename: Zbigniew
authors.initials: Z
authors.lastname: Polanski
authors.forename: Maria A
authors.initials: MA
authors.lastname: Ciemerych