title: Possible involvement of Class III phosphatidylinositol-3-kinase in meiotic progression of porcine oocytes beyond germinal vesicle stage.
abstract: Phosphatidylinositol-3-kinases (PI3Ks) play pivotal roles in meiotic progression of oocytes from metaphase I to metaphase II stage. Using a Class III-specific inhibitor of PI3K, 3-methyladenine (3MA), this study shows that Class III PI3K may be essential for meiotic progression of porcine oocytes beyond germinal vesicle (GV) stage. Treatment of immature porcine oocytes with 3MA for 22-42 h arrested them at the GV stage, irrespective of the presence or absence of cumulus cells. Furthermore, a significantly high proportion (60.9 ± 13.8%) of 3MA-treated oocytes acquired a nucleolus completely surrounded by a rim of highly condensed chromatin (GV-II stage). The GV-arresting effect of 3MA was, however, completely reversible upon their further culture in the absence of 3MA for 22 h. When cumulus-oophorus-complexes (COCs), arrested at the GV stage for 22 h by 3MA, were further cultured for 22 h in the absence of 3MA, 96.1 ± 1.5% of oocytes reached the MII stage at 42 h of IVM and did not differ from non-treated control oocytes with respect to their ability to fertilize, cleave and form blastocyst (P > 0.05) upon in vitro fertilization (IVF) or parthenogenetic activation (PA). These data suggest that 3MA efficiently blocks and synchronizes the meiotic progression of porcine oocytes at the GV stage without affecting their ooplasmic maturation in terms of post-fertilization/activation in vitro embryonic development. Our data also provide indirect evidence for the likely participation of Class III PI3K in meiotic maturation of porcine oocyte beyond the GV stage.
authors.affiliation: Department of Animal Biotechnology, Animal Resources Research Center/Bio-Organ Research Center, Konkuk University, Seoul 143 701, South Korea.
authors.forename: Myung Rae
authors.initials: MR
authors.lastname: Park
authors.forename: Mukesh Kumar
authors.initials: MK
authors.lastname: Gupta
authors.forename: Hye Ran
authors.initials: HR
authors.lastname: Lee
authors.forename: Ziban Chandra
authors.initials: ZC
authors.lastname: Das
authors.forename: Sang Jun
authors.initials: SJ
authors.lastname: Uhm
authors.forename: Hoon Taek
authors.initials: HT
authors.lastname: Lee
mesh_terms: D000225:Adenine / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D002478:Cells, Cultured; D054885:Cumulus Cells / Q000166:cytology; D046149:Embryo Culture Techniques / Q000662:veterinary; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D005307:Fertilization in Vitro / Q000662:veterinary; D008540:Meiosis / Q000502:physiology*; D008677:Metaphase / Q000502:physiology; D009865:Oocytes / Q000166:cytology* / Q000187:drug effects / Q000502:physiology; D010312:Parthenogenesis; D058539:Phosphatidylinositol 3-Kinase / Q000502:physiology*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D013552:Swine
chemical_list: D004791:Enzyme Inhibitors; D000081082:Phosphoinositide-3 Kinase Inhibitors; C025946:3-methyladenine; D058539:Phosphatidylinositol 3-Kinase; D000225:Adenine