title: Erp1/Emi2 is essential for the meiosis I to meiosis II transition in Xenopus oocytes.
abstract: Erp1 (also called Emi2), an inhibitor of the APC/C ubiquitin ligase, is a key component of cytostatic factor (CSF) responsible for Meta-II arrest in vertebrate eggs. Reportedly, however, Erp1 is expressed even during meiosis I in Xenopus oocytes. If so, it is a puzzle why normally maturing oocytes cannot arrest at Meta-I. Here, we show that actually Erp1 synthesis begins only around the end of meiosis I in Xenopus oocytes, and that specific inhibition of Erp1 synthesis by morpholino oligos prevents entry into meiosis II. Furthermore, we demonstrate that premature, ectopic expression of Erp1 at physiological Meta-II levels can arrest maturing oocytes at Meta-I. Thus, our results show the essential role for Erp1 in the meiosis I/meiosis II transition in Xenopus oocytes and can explain why normally maturing oocytes cannot arrest at Meta-I.
authors.affiliation: Department of Biology, Graduate School of Sciences, Kyushu University, Hakozaki 6-10-1, Fukuoka 812-8581, Japan.
authors.forename: Munemichi
authors.initials: M
authors.lastname: Ohe
authors.forename: Daigo
authors.initials: D
authors.lastname: Inoue
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Kanemori
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Sagata
mesh_terms: D000818:Animals; D018797:Cell Cycle Proteins / Q000378:metabolism; D044783:F-Box Proteins / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D015151:Immunoblotting; D007150:Immunohistochemistry; D008540:Meiosis / Q000502:physiology*; D009841:Oligonucleotides; D009865:Oocytes / Q000502:physiology*; D011494:Protein Kinases / Q000378:metabolism; D014981:Xenopus / Q000502:physiology*; D029867:Xenopus Proteins / Q000378:metabolism*
chemical_list: D018797:Cell Cycle Proteins; D044783:F-Box Proteins; C498166:FBXO43 protein, Xenopus; D009841:Oligonucleotides; D029867:Xenopus Proteins; D011494:Protein Kinases; C070577:CDK1 protein, Xenopus