title: Okadaic acid-sensitive phosphatase is related to MII/G1 transition in mouse oocytes.
abstract: It is reported that okadaic acid (OA)-sensitive phosphatase is related to mitogen-activated protein kinase (MAPK)/p90rsk activation in mammalian oocytes. OA is also involved in the positive feedback loop between M phase-promoting factor (MPF) and cdc25c in Xenopus oocytes during meiotic maturation. However, the effect of phosphatase inhibition by OA on MPF and MAPK activities at the MII/G1 in oocytes remains unknown. The aim of this study is to clarify the relationship between OA-sensitive phosphatase and mitosis MII/G1 transition in mouse oocytes. MII-arrested oocytes were, isolated from mice, inseminated and cultured in TYH medium (control group) or TYH medium supplemented with 2.5 μM of OA (OA group). Histone H1 kinase and myelin basic protein (MBP) kinase activities were measured as indicators of MPF and p42 MAPK activities after insemination. Phosphorylation of cdc25c after insemination was analized in OA and control group by western blotting. Seven hours after insemination a pronucleus (PN) was formed in 84.1% (69/85) of oocytes in the control group. However, no PN was formed in oocytes of the OA group (p < 0.001). Although MPF and MAPK activities in the control group significantly decreased at 3, 4, 5, and 7 h after insemination, these decreases were significantly inhibited by OA addition (p < 0.05). Furthermore, OA addition prevented cdc25c dephosphorylation 7 h after insemination. In conclusion, OA-sensitive phosphatase correlates with inactivation of MPF and MAPK, and with the dephosphorylation of cdc25c at the MII/G1 transition in mouse oocytes.
authors.affiliation: Department of Obstetrics and Gynecology, University of Tokushima, Institute for Health Biosciences, 3-18-15 Kuramoto Tokushima 770-8503, Japan.
authors.forename: Naoko
authors.initials: N
authors.lastname: Moride
authors.forename: Akira
authors.initials: A
authors.lastname: Kuwahara
authors.forename: Ayako
authors.initials: A
authors.lastname: Sutoh
authors.forename: Yu
authors.initials: Y
authors.lastname: Tanaka
authors.forename: Yukari
authors.initials: Y
authors.lastname: Mukai
authors.forename: Mizuho
authors.initials: M
authors.lastname: Yamashita
authors.forename: Toshiya
authors.initials: T
authors.lastname: Matsuzaki
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Yasui
authors.forename: Minoru
authors.initials: M
authors.lastname: Irahara
mesh_terms: D000818:Animals; D002455:Cell Division / Q000187:drug effects; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D005307:Fertilization in Vitro / Q000187:drug effects; D016193:G1 Phase / Q000187:drug effects; D008297:Male; D016200:Maturation-Promoting Factor / Q000378:metabolism; D000090204:Mesothelin; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D019319:Okadaic Acid / Q000494:pharmacology*; D009865:Oocytes / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology*; D010749:Phosphoprotein Phosphatases / Q000378:metabolism*; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism; D020687:cdc25 Phosphatases / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: D004791:Enzyme Inhibitors; C000715528:Msln protein, mouse; D019319:Okadaic Acid; D011494:Protein Kinases; C102333:histone H1 kinase; D016200:Maturation-Promoting Factor; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; C067024:okadaic acid-sensitive phosphatase; D010749:Phosphoprotein Phosphatases; C517010:Cdc25c protein, mouse; D020687:cdc25 Phosphatases; D000090204:Mesothelin