DAX1 (for dosage-sensitive sex reversal, adrenal hypoplasia congenital critical region on the X chromosome, gene 1; also called NROB1) mutations are responsible for adrenal failure and hypogonadotropic hypogonadism in patients with adrenal hypoplasia congenita (AHC), through a loss of trans-repression of SF-1 (for steroidogenic factor-1)-mediated StAR (for steroidogenic acute regulatory protein) and LHbeta transcriptional activities and a reduction of GnRH expression.
Therefore, we examined AKR1B1 gene expression in human fetal adrenals, adrenocortical cell line, and tumors and compared the results with the expression of steroidogenic genes (StAR and CYP11A) and regulators of adrenal cortex development [steroidogenic factor-1 (SF-1) and dosage-sensitive sex reversal-adrenal hypoplasia congenita critical region on the X chromosome, gene 1 (DAX1)].
Dosage-sensitive sex reversal adrenal hypoplasia congenita critical region on the X chromosome gene 1 (DAX-1) inhibits SF-1-mediated induction of MIS and other steroidogenic genes, whereas Wilms' tumor suppressor gene (WT1) augments SF-1-mediated MIS expression.
We conclude that DAX-1 can inhibit SF-1 transcriptional activity and suggest that the loss of this inhibitory property in DAX-1 may account in part for the phenotype of AHC.