A transgenic insertion upstream of sox9 is associated with dominant XX sex reversal in the mouse.
In most mammals, male development is triggered by the transient expression of the Y-chromosome gene, Sry, which initiates a cascade of gene interactions ultimately leading to the formation of a testis from the indifferent fetal gonad. Several genes, in particular Sox9, have a crucial role in this pathway. Despite this, the direct downstream targets of Sry and the nature of the pathway itself remain to be clearly established. We report here a new dominant insertional mutation, Odsex (Ods), in which XX mice carrying a 150-kb deletion (approximately 1 Mb upstream of Sox9) develop as sterile XX males lacking Sry. During embryogenesis, wild-type XX fetal gonads downregulate Sox9 expression, whereas XY and XX Ods/+ fetal gonads upregulate and maintain its expression. We propose that Ods has removed a long-range, gonad-specific regulatory element that mediates the repression of Sox9 expression in XX fetal gonads. This repression would normally be antagonized by Sry protein in XY embryos. Our data are consistent with Sox9 being a direct downstream target of Sry and provide genetic evidence to support a general repressor model of sex determination in mammals.
Bishop
C E
CE
Department of Obstetrics & Gynecology, Baylor College of Medicine, Houston, Texas, USA. bishop@bcm.tmc.edu
Whitworth
D J
DJ
Qin
Y
Y
Agoulnik
A I
AI
Agoulnik
I U
IU
Harrison
W R
WR
Behringer
R R
RR
Overbeek
P A
PA
D000818:Animals; D001483:Base Sequence; D002874:Chromosome Mapping; D017931:DNA Primers / Q000235:genetics; D012734:Disorders of Sex Development; D005260:Female; D005799:Genes, Dominant; D006609:High Mobility Group Proteins / Q000235:genetics*; D017403:In Situ Hybridization; D017404:In Situ Hybridization, Fluorescence; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D010375:Pedigree; D010641:Phenotype; D055758:SOX9 Transcription Factor; D017384:Sequence Deletion; D014157:Transcription Factors / Q000235:genetics*
D017931:DNA Primers; D006609:High Mobility Group Proteins; D055758:SOX9 Transcription Factor; C527933:Sox9 protein, mouse; D014157:Transcription Factors