Nobox gene key to proper egg development

While humorists ponder the old saw about the chicken and the egg, researchers at Baylor College of Medicine focus on the egg, which would not exist without the master geneNobox, which they describe in this week’s issue of the journal Science.

When mice lack this gene, their eggs do not develop and they are infertile, said Dr. Aleksandar Rajkovic, a BCM assistant professor of obstetrics and gynecology. Their condition resembles that of women who have ovarian failure, he said. Studying these mice may provide important clues about mechanisms of ovarian failure. It may also in the future enable “genetic control of mammalian reproductive life-span and improve our ability to regulate fertility and generate mature eggs in vitro.”

In a report in today’s issue of the journal Science, Rajkovic and his colleagues describe the actions of Nobox, which is a homeobox gene capable of regulating others. They showed that in mice, a lack of the Nobox gene resulted in the loss of activity of other genes that are active only in the oocytes.

Nobox appears to govern the activity of genes crucial to the development of follicles, which hold the immature eggs cells or oocytes. These follicles are supposed thicken as the mouse develops. Without Nobox, the follicles do not develop and the oocytes deteriorate.

“The preparation for early embryogenesis (formation of embryos) begins with folliculogenesis (formation of follicles),” said Rajkovic. “When this gene is deleted, there is no folliculogenesis and no oocytes.”

Others who participated in the research include Drs. Stephanie A. Pangas, Daniel Ballow, Nobuhiro Suzumori and Martin M. Matzuk.