Growing up male is a genetic lifestyle decision - early in embryonic development, genes on the Y chromosome activate the development of specialized cells that ultimately become the testes. Without this 'on switch' for maleness, the developing gonads become ovaries by default and the embryo develops as a female.
A study of mice now shows how the developing gonads start out on this road to maleness. In a paper published online in Nature, geneticists Robin Lovell-Badge and Ryohei Sekido describe how a gene called Sry, carried on the Y chromosome, boosts another gene elsewhere in the genome that in turn governs the development of somatic cells that support the germ cells so that they produce sperm.
By studying gene expression patterns in developing mouse embryos, the researchers deduced that Sry produces a protein that combines with another protein, steroidogenic factor 1 (SF1). This complex then binds to a DNA region that boosts the expression of another gene, Sox9, which controls a host of genes involved in sperm development.
Elucidating this pathway not only reveals how maleness develops from the 'default' female developmental pathway; defects in this process may also explain how people who are genetically 'male' or 'female' end up developing the 'wrong' sexual anatomy.
Robin Lovell-Badge (National Institute for Medical Research, London, UK)
Abstract available online.
(C) Nature press release.
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