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Protein Tyrosine Kinase Wee1B Is Essential for Metaphase II Exit in Mouse Oocytes

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Science  22 Apr 2011:
Vol. 332, Issue 6028, pp. 462-465
DOI: 10.1126/science.1199211

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Abstract

Waves of cyclin synthesis and degradation regulate the activity of Cdc2 protein kinase during the cell cycle. Cdc2 inactivation by Wee1B-mediated phosphorylation is necessary for arrest of the oocyte at G2-prophase, but it is unclear whether this regulation functions later during the metaphase-to-anaphase transition. We show that reactivation of a Wee1B pathway triggers the decrease in Cdc2 activity during egg activation. When Wee1B is down-regulated, oocytes fail to form a pronucleus in response to Ca2+ signals. Calcium-calmodulin–dependent kinase II (CaMKII) activates Wee1B, and CaMKII-driven exit from metaphase II is inhibited by Wee1B down-regulation, demonstrating that exit from metaphase requires not only a proteolytic degradation of cyclin B but also the inhibitory phosphorylation of Cdc2 by Wee1B.

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