Fertilization differently affects the levels of cyclin B1 and M-phase promoting factor activity in maturing and metaphase II mouse oocytes
Autor: | Victoria Nixon, Karl Swann, Maria A. Ciemerych, Marek Maleszewski, Anna Ajduk |
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Rok vydání: | 2008 |
Předmět: |
Embryology
Maturation-Promoting Factor Gene Expression Fertilization in Vitro Cyclin B Biology Dephosphorylation Mice Oogenesis Endocrinology Human fertilization Cyclin-dependent kinase CDC2 Protein Kinase Animals Cyclin B1 Cycloheximide Prometaphase Luciferases Cells Cultured Metaphase reproductive and urinary physiology Protein Synthesis Inhibitors urogenital system Kinase Obstetrics and Gynecology Cell Biology M-Phase Promoting Factor Glutathione Sperm Cell biology Mice Inbred C57BL Reproductive Medicine Fertilization Mesothelin Mice Inbred CBA Oocytes biology.protein Calcium Female Protein Kinases |
Zdroj: | REPRODUCTION. 136:741-752 |
ISSN: | 1741-7899 1470-1626 |
Popis: | Fertilization affects levels of cyclin B1 and M-phase promoting factor (MPF) activity in maturing and metaphase II mouse oocytes in two distinct ways. In metaphase II oocytes, it leads to a Ca2+-dependent, continuous degradation of cyclin B1 and inactivation of cyclin dependent kinase (CDC2A)–cyclin B1 complex (MPF). In this paper, we show that neither mono- nor polyspermic fertilization of prometaphase I and metaphase I oocytes triggered degradation of cyclin B1. However, polyspermic fertilization of prometaphase I oocytes led to a transient decrease in MPF activity that lasted for 2 h. The inactivation of MPF in polyspermic prometaphase I oocytes did not depend on the fertilization-induced increase in the cytoplasmic concentration of free Ca2+ions, but was caused, at least in part, by dephosphorylation of CDC2A at threonine 161 (Thr161). We found that polyspermic fertilization did not affect glutathione levels in prometaphase I oocytes, and concluded that the decrease in MPF activity and dephosphorylation of CDC2A at Thr161 in polyspermic prometaphase I oocytes were not caused by a change in the redox status of the cell induced by an introduction of excessive amount of sperm protamines. Instead, we propose that inactivation of MPF activity in polyspermic maturing oocytes is caused by a change in nucleo-cytoplasmic ratio that leads to a ‘titration’ of kinases and phosphatases responsible for keeping MPF in an active state. This idea is supported by the finding that oocytes fused with thymocytes rather than spermatozoa also showed a transient decrease in MPF activity. |
Databáze: | OpenAIRE |
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