DAX-1 inhibits SF-1-mediated transactivation via a carboxy-terminal domain that is deleted in adrenal hypoplasia congenita.
X-linked adrenal hypoplasia congenita (AHC) with hypogonadotropic hypogonadism was recently shown to be caused by mutations in a gene referred to as DAX-1, which encodes a novel member of the orphan nuclear receptor family. DAX-1 is homologous to other nuclear receptors in its carboxy-terminal region, but it lacks the characteristic zinc finger DNA-binding domain. The tissue distribution of DAX-1 (adrenal cortex, gonads, hypothalamus, and pituitary) is the same as that of another orphan nuclear receptor, steroidogenic factor 1 (SF-1), that is required for development of the adrenal glands and gonads. We examined whether DAX-1 and SF-1 might interact in the regulation of SF-1-responsive target genes. Coexpression of DAX-1 and SF-1 inhibited SF-1-mediated transactivation. DAX-1 was shown to interact directly with SF-1 in in vitro protein binding studies; however, it did not interfere with SF-1 binding to DNA in gel mobility shift assays. Transactivation by GAL4-SF-1 constructs was inhibited by DAX-1, indicating that neither the SF-1 DNA-binding domain nor the SF-1 binding sites are required for inhibition by DAX-1. A series of DAX-1 deletion mutants localized the inhibitory domain to the carboxy-terminal region of the protein. Deletion of this domain also reduced basal transcriptional silencing by GAL4-DAX-1. This inhibitory domain has been deleted in all naturally occurring AHC deletion mutants described to date. In addition, two naturally occurring point mutations in DAX-1 exhibited impaired inhibition of SF-1. 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.
Ito
M
M
Division of Endocrinology, Metabolism, and Molecular Medicine, Northwestern University Medical School, Chicago, Illinois 60611, USA.
Yu
R
R
Jameson
J L
JL
D000309:Adrenal Insufficiency / Q000151:congenital / Q000235:genetics*; D000818:Animals; D002460:Cell Line; D057137:DAX-1 Orphan Nuclear Receptor; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism*; D051717:Fushi Tarazu Transcription Factors; D008040:Genetic Linkage; D018398:Homeodomain Proteins; D006801:Humans; D007006:Hypogonadism / Q000151:congenital / Q000235:genetics; D051379:Mice; D017354:Point Mutation; D011485:Protein Binding; D018160:Receptors, Cytoplasmic and Nuclear; D018168:Receptors, Retinoic Acid / Q000235:genetics* / Q000378:metabolism; D011988:Receptors, Thyroid Hormone / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012097:Repressor Proteins; D017384:Sequence Deletion; D054339:Steroidogenic Factor 1; D013577:Syndrome; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism*; D014158:Transcription, Genetic; D015533:Transcriptional Activation / Q000502:physiology*; D014960:X Chromosome
D057137:DAX-1 Orphan Nuclear Receptor; D004268:DNA-Binding Proteins; D051717:Fushi Tarazu Transcription Factors; D018398:Homeodomain Proteins; C539965:NR0B1 protein, human; C515057:NR5A1 protein, human; C539966:Nr0b1 protein, mouse; D018160:Receptors, Cytoplasmic and Nuclear; D018168:Receptors, Retinoic Acid; D011988:Receptors, Thyroid Hormone; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D054339:Steroidogenic Factor 1; D014157:Transcription Factors; C515058:steroidogenic factor 1, mouse; D004247:DNA