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Effect of KN-62, a selective inhibitor of calmodulin-dependent kinase II, on mouse oocyte activation
1Department of Obstetrics and Gynecology, Saitama Chuo Hospital, Japan.
Purpose:
Our purpose was to determine the association of calmodulin-dependent protein kinase II (CaMKII) with oocyte activation and to explore the network of protein kinases during mammalian fertilization.
Methods:
Mouse M-II oocytes were collected after superovulation induced by PMSG-hCG injection. The oocytes were inseminated or artificially activated by Ca ionophore (A23187) or 12-O-tetradecanoyl phorbol 13-acetate (TPA). The effects of KN-62, a specific and selective inhibitor of calmodulin-dependent protein kinase II, on second polar body emission (2PBE), pronuclear formation (PF), and cortical granule exocytosis (CGE) during fertilization or after artificial oocyte activation were investigated.
Results:
KN-62 inhibited 2PBE and PF after sperm or Ca ionophore inducing activation. Additionally, PF was inhibited by KN-62 after TPA activation, whereas KN-62 did not inhibit CGE in any case. KN-04, an inactive form of KN-62, did not inhibit significantly 2PBE, CGE, or PF. When oocytes were exposed to KN-62 after Ca ionophore or TPA activation, no inhibitory effects on 2PBE or PF were observed.
Conclusions:
The CaMKII activation that occurs after fertilization or artificial activation of mouse oocytes is presumably secondary to increases in the intracellular free calcium concentration. As determined by the use of inhibitor, CaMKII activity is associated with 2PBE and PF but not with CGE.
Insights
Calmodulin-dependent protein kinase II (CaMKII) is involved in mouse oocyte activation, specifically in second polar body emission and pronuclear formation, but not cortical granule exocytosis.
Area of Science:
- Reproductive Biology
- Cell Signaling
- Molecular Biology
Background:
- Oocyte activation is a critical process in mammalian fertilization.
- Protein kinases play crucial roles in regulating oocyte activation.
- Calmodulin-dependent protein kinase II (CaMKII) is a key signaling molecule.
Purpose of the Study:
- To determine the association of CaMKII with oocyte activation.
- To explore the protein kinase network during mammalian fertilization.
Main Methods:
- Mouse M-II oocytes were collected and inseminated or artificially activated.
- The effects of KN-62, a CaMKII inhibitor, were investigated on key activation events.
- Second polar body emission (2PBE), pronuclear formation (PF), and cortical granule exocytosis (CGE) were assessed.
Main Results:
- KN-62 inhibited 2PBE and PF following sperm or calcium ionophore activation.
- KN-62 also inhibited PF after TPA activation but did not affect CGE.
- An inactive KN-62 analog (KN-04) showed no significant inhibition.
Conclusions:
- CaMKII activation in oocytes is likely secondary to calcium concentration changes.
- CaMKII activity is linked to 2PBE and PF during oocyte activation.
- CaMKII is not associated with CGE during mammalian fertilization.