Stowers Institute's Hawley Lab identifies factors responsible for restart of mei...( The Stowers Institutes Hawley Lab h...)

The Stowers Institutes Hawley Lab has identified a pair of proteins that work in concert to restart the meiotic cycle of oocytes following a natural period of dormancy.

The Hawley Lab has described the dual actions of these two proteins as the Sleeping Beauty Kiss that awakens the long-dormant egg, allowing for production of a mature oocyte ready for fertilization. The findings appear in the Dec. 4, 2007 issue of PLoS Biology.

The long period of dormancy that interrupts the process that parses out the correct number of chromosomes is characteristic of female meiosis. The cells that will become oocytes in human females develop during fetal development and begin the actual process of meiosis before birth, but the oocytes remain in a suspended state until the female reaches sexual maturity.

Extended periods of dormancy may last many years in organisms like humans, but shorter periods of meiotic arrest can be found in simpler, more easily studied species like the fruit fly the model used by the Hawley Lab in this work. In the fruit fly, oocyte development is arrested for 3-4 days at exactly the same point in meiosis as in humans.

The long period of meiotic arrest has mystified biologists for over a century because it raises the question of just how the sleeping oocyte is reawakened. The Hawley Lab addressed this question and determined that there are two molecular solutions at play: the controlled expression of a protein that restarts the cell cycle and the inactivation of an inhibitory protein that had previously prevented the restart of meiosis.

This work led us to the conclusion that the restart of the meiotic cycle in Drosophila depends on two mechanisms, said Youbin Xiang, Ph.D., Research Specialist II and first author on the paper. First, the controlled expression of an activator, known as Polo kinase, and second, the presence of a regulatory protein called Matrimony, which binds to and physically inacti
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