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Dax1 antagonizes Sry action in mammalian sex determination

A Swain1, V Narvaez, P Burgoyne

  • 1Division of Developmental Genetics, MRC National Institute for Medical Research, London, UK.

Nature
|March 5, 1998
PubMed

Insights

The gene DAX1 is largely responsible for dosage-sensitive sex reversal in XY individuals. Its expression levels critically influence mammalian sex determination, especially when interacting with SRY gene alleles.

Area of Science:

  • Genetics
  • Developmental Biology
  • Endocrinology

Background:

  • DAX1, a nuclear hormone receptor superfamily gene, is implicated in dosage-sensitive sex reversal (DSS), where XY individuals with Xp21 duplications develop as females.
  • Mammalian sex determination involves complex gene interactions, with SRY on the Y chromosome typically initiating male development.

Purpose of the Study:

  • To investigate the role of DAX1 in dosage-sensitive sex reversal.
  • To elucidate the gene's function in mammalian sex determination pathways.

Main Methods:

  • Analysis of XY mice carrying Dax1 transgenes at high expression levels.
  • Testing Dax1 transgenes against weak alleles of the Y-chromosome gene Sry.

Main Results:

  • High-level Dax1 expression in XY mice caused delayed testis development.
  • Complete sex reversal in XY mice occurred when Dax1 transgenes were combined with weak Sry alleles.
  • DAX1 was identified as the primary genetic factor in dosage-sensitive sex reversal.

Conclusions:

  • DAX1 plays a crucial role in dosage-sensitive sex reversal.
  • Precise gene expression levels and timing are critical for mammalian sex determination.
  • This study provides a model for understanding early mammalian sex determination events.

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