Possible role for Ca2+ calmodulin-dependent protein kinase II as an effector of the fertilization Ca2+ signal in mouse oocyte activation

• Published in: Molecular human reproduction 2002-08, Vol.8 (8), p.750-757
• Main Authors: Tatone, C., Delle Monache, S., Iorio, R., Caserta, D., Di Cola, M., Colonna, R.
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; calcium; cortical granule exocytosis; fertilization; Fundamental and applied biological sciences. Psychology; Mammalian female genital system; Morphology. Physiology; MPF inactivation; protein kinases; Vertebrates: reproduction
• ISSN: 1360-9947; 1460-2407; 1460-2407
• DOI: 10.1093/molehr/8.8.750

The present study shows that Ca2+ calmodulin-dependent protein kinase II (CaM kinase II) is physiologically activated in fertilized mouse oocytes and is involved in the Ca2+ response pathways that link the fertilization Ca2+ signal to meiosis resumption and cortical granule (CG) exocytosis. After 10 min of insemination, CaM kinase II activity increased transiently, then peaked at 1 h and remained elevated 30 min later when most of the oocytes had completed the emission of the second polar body. In contrast, in ethanol-activated oocytes the early transient activation of CaM kinase II in response to a monotonic Ca2+ rise was not followed by any subsequent increase. Inhibition of CaM kinase II by 20 μmol/l myristoylated-AIP (autocamtide-2-related inhibitory peptide) negatively affected MPF (maturing promoting factor) inactivation, cell cycle resumption and CG exocytosis in both fertilized and ethanol-activated oocytes. These results indicate that the activation of CaM kinase II in mouse oocytes is differently modulated by a monotonic or repetitive Ca2+ rise and that it is essential for triggering regular oocyte activation.