Female embryonic sexual development driven by univer...(lex and ambiguous however leading some t...)
lex and ambiguous, however, leading some to reject it.
Yao and graduate student Chia-Feng Liu wanted to investigate a particular player in the cast of molecules known to be involved in transforming the primordium into testis or ovary. This molecule, beta-catenin, is an important regulator of cell proliferation and differentiation. When it functions as a transcription factor, it turns other genes on or off. Without beta-catenin, which is expressed in many organs and tissues, an embryo will not survive.
Yao and Liu knew that other proteins also were critical to the development of ovaries in particular. Mice that lacked the genes for a signaling protein, known as Wnt4, or another secreted protein, called R-spondin1, experienced a partial female-to-male sex reversal: They formed ovaries, but with male characteristics, such as blood-vessel structures like those in testes. Humans with mutations in their WNT4 and R-spondin1 genes had similar malformations of the sex organs.
Other studies had indicated that beta-catenin was important to the action of Wnt4 and R-spondin1 in various tissues. But no studies had found direct genetic proof that beta-catenin was involved in regulating how the ovaries developed.
To determine whether beta-catenin had a role in forming the ovaries, the researchers developed a mouse embryo in which the beta-catenin gene could be shut off at the earliest stage of development of the gonads while remaining functional in other organs.
"To our surprise, the ovaries still formed," Yao said. But male sexual structures also appeared, creating an amalgamation of male and female sexual structures that looked very much like those produced when the Wnt4 or R-spondin1 genes were mutated or missing.
"That tells us very conclusively that beta-catenin is an internal regulator of this pathway," Yao said.
To see how the absence of beta-catenin would affect testes formation, the researchers repeated the exp
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| Contact: Diana Yates, Life Sciences Editor diya@illinois.edu 217-333-5802 University of Illinois at Urbana-Champaign Source:Eurekalert |
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 Female embryonic sexual development driven by universal factor |
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