Maturation-promoting factor governs mitogen-activated protein kinase activation and interphase suppression during meiosis of rat oocytes.
Meiosis is a particular example of a cell cycle, characterized by two successive divisions without an intervening interphase. Resumption of meiosis in oocytes is associated with activation of maturation-promoting factor (MPF) and mitogen-activated protein kinase (MAPK). The activity of MPF declines during the transition between the two meiotic divisions, whereas the activity of MAPK is sustained. Attempts to disclose the interplay between these key regulators of meiosis in both amphibian and mammalian oocytes generated contradictory results. Furthermore, the enzyme that governs the suppression of interphase in mammals is still unidentified. To our knowledge, we provide herein the first demonstration in a mammalian system that inhibition of MPF at reinitiation of meiosis abrogated Mos expression and MAPK activation. We also show that oocytes, in which reactivation of MPF at completion of the first telophase was prevented, exhibited an interphase nucleus with decondensed chromosomes. Inhibition of MAPK did not interfere with the progression to the second meiotic metaphase but, rather, resulted in parthenogenic activation. We conclude that in rat oocytes, MPF regulates MAPK activation and its timely reactivation prevents the oocytes from entering interphase.
Josefsberg
Liat Ben-Yehoshua
LB
Department of Biological Regulation, The Weizmann Institute of Science, Rehovot 76100, Israel.
Galiani
Dalia
D
Lazar
Shlomi
S
Kaufman
Orit
O
Seger
Rony
R
Dekel
Nava
N
D000818:Animals; D000242:Cyclic AMP / Q000494:pharmacology; D019926:Cyclin B / Q000378:metabolism; D056744:Cyclin B1; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D005260:Female; D007399:Interphase; D016200:Maturation-Promoting Factor / Q000502:physiology*; D008540:Meiosis / Q000502:physiology*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D017232:Oncogene Proteins v-mos / Q000378:metabolism; D009865:Oocytes / Q000166:cytology*; D051381:Rats; D017208:Rats, Wistar
C534701:Ccnb1 protein, rat; D019926:Cyclin B; D056744:Cyclin B1; D017232:Oncogene Proteins v-mos; D000242:Cyclic AMP; D016200:Maturation-Promoting Factor; D020928:Mitogen-Activated Protein Kinases