Timing of Plk1 and MPF activation during porcine oocyte maturation.
A Polo-like kinase 1 (Plk1) appears involved in an autocatalytic loop between CDC25C phosphatase and M phase promoting factor (MPF) in Xenopus oocytes and leads to activation of MPF that is required for germinal vesicle breakdown (GVBD). Although similar evidence for such a role of Plk1 in MPF activation during maturation of mammalian oocytes is absent, changes in Plk1 enzyme activity correlate with MPF activation, Plk1 co-localizes with MPF, and microinjection of antibodies neutralizing Plk1 delays GVBD. In this study, we exploited the prolonged time required for maturation of porcine oocytes to define precisely the timing of Plk1 and MPF activation during maturation. GVBD typically occurs between 24 and 26 hr of culture in vitro and meiotic maturation is completed after 40-44-hr culture. We find that Plk1 is activated before MPF, which is consistent with its role in activating MPF in mammalian oocytes.
Department of Biology, University of Pennsylvania, Philadelphia, PA 19104-6018, USA. anger@sas.upenn.edu
Martin
M
Anger
Jiri
J
Klima
Michal
M
Kubelka
Radek
R
Prochazka
Jan
J
Motlik
Richard M
RM
Schultz
D000818:Animals; D000906:Antibodies / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002478:Cells, Cultured; D004789:Enzyme Activation; D004795:Enzyme Stability; D006801:Humans; D016200:Maturation-Promoting Factor / Q000378:metabolism*; D008540:Meiosis / Q000502:physiology*; D009865:Oocytes / Q000166:cytology / Q000502:physiology*; D011494:Protein Kinases / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D013552:Swine; D013997:Time Factors; D000097869:Polo-Like Kinase 1
D000906:Antibodies; D018797:Cell Cycle Proteins; D016200:Maturation-Promoting Factor; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D000097869:Polo-Like Kinase 1