Gene that keeps females female identified

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Washington, Dec 11 (ANI): Here's what keeps females female: Ovaries spend their entire existence suppressing an innate capacity to become male, says a new study.

According to researchers, the findings study could have important implications for understanding sex disorders in children and premature menopause in women.

The study found that the ovaries of adult female mice could be 'reprogrammed' into non-sperm-producing male testes by silencing a single gene.

Mathias Treier of the University of Cologne in Germany said that no one would have previously suspected or believed that an adult organ could be "transdifferentiated" to such an extent by changing a single gene.

Until a few years ago, conventional wisdom held that terminally differentiated organs in adult mammals couldn't be reprogrammed. The new findings add to a growing list of exceptions to that rule.

They also revise scientists' understanding of sex determination, which held that ovaries are the default identity for the gonads. In almost all mammals, males are XY and females XX.

A transcription factor known as SRY, which is found on the Y chromosome, is normally responsible for triggering the indifferent gonads to develop as testes rather than ovaries. SRY induces the activity of another gene, known as Sox9, which takes over from there.

Now the researchers show that the transcription factor, FOXL2, is required to keep Sox9 turned off in the adult ovary. Without it, Sox9 comes on and the identity of ovarian cells "flip-flops," turning them into testicular cells.

In the new study, they created a mouse in which they could turn the FOXL2 gene off in the ovarian follicles at any time. When turned off in an adult animal, they report that testis-specific genes, including Sox9, immediately switch on.

With that change in the genetic program, granulosa and theca cell lineages of the ovary turn into Sertoli-like and Leydig-like cells normally seen in the testes and they begin to pump out testosterone.

"This shows that the maintenance of the ovarian phenotype is an active process throughout life. Like Yin and Yang, FOXL2 and SOX9 oppose each other's action to ensure together the establishment and maintenance of the different female and male supporting cell types respectively," Treier said.

The study is published in the December 11th issue of the journal Cell. (ANI)

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