GATA-6 is expressed in the human adrenal and regulates transcription of genes required for adrenal androgen biosynthesis.
GATA-6 and GATA-4 are members of a family of transcription factors (GATA 1-6) that share conserved zinc-finger DNA binding domains. Using semiquantitative RT-PCR, we found that the human adrenal expresses mRNA for GATA-6 but not GATA-4. A recent study showed GATA-6 expression in the adrenal reticularis, the source of adrenal androgens. To investigate the role of GATA-6 in regulation of adrenal cell steroidogenesis, luciferase reporter constructs containing the 5'-flanking DNA from steroidogenic acute regulatory protein, cholesterol side-chain cleavage (CYP11A), 17alpha-hydroxylase (CYP17), and dehydroepiandrosterone-sulfotransferase (SULT2A1) were cotransfected with an expression vector containing GATA-6 into adrenal NCI-H295R cells and nonsteroidogenic HEK293 cells. All promoter/reporter constructs were increased by GATA-6 in the adrenal model. However, in the HEK293 cells only SULT2A1 reporter activity was increased by GATA-6. One key difference between H295R and HEK293 cell lines is the differential expression of steroidogenic factor 1 (SF1). Transfection of HEK293 cells with both GATA-6 and SF1 significantly increased transcriptional activation of all reporter constructs above the effect of GATA-6 or SF1 alone. To determine whether the action of GATA-6 required SF1, we transfected HEK293 cells with each promoter construct plus and minus GATA-6, SF1, and/or the orphan nuclear repressor DAX1. DAX1 opposed SF1-activated transcription of many genes and abolished the GATA-6/SF1 ability to increase reporter activity. These results suggest that the adrenal uses GATA-6 to enhance transcription of steroid-metabolizing enzymes needed to produce dehydroepiandrosterone sulfate. Additionally, GATA-6 works in synergy with SF1 to maximally increase expression of enzymes needed to produce adrenal androgens.
Jimenez
Patricia
P
Department of Obstetrics and Gynecology, Division of Reproductive Endocrinology and Infertility, University of Texas Southwestern Medical Center, Dallas, Texas 75235-9032, USA.
Saner
Karla
K
Mayhew
Bobbie
B
Rainey
William E
WE
D000311:Adrenal Glands / Q000378:metabolism*; D000728:Androgens / Q000096:biosynthesis* / Q000235:genetics*; D002460:Cell Line; D057137:DAX-1 Orphan Nuclear Receptor; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D004357:Drug Synergism; D005260:Female; D051717:Fushi Tarazu Transcription Factors; D050993:GATA6 Transcription Factor; D018398:Homeodomain Proteins; D006801:Humans; D006080:Ovarian Follicle / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D018160:Receptors, Cytoplasmic and Nuclear; D018168:Receptors, Retinoic Acid; D012097:Repressor Proteins / Q000494:pharmacology; D054339:Steroidogenic Factor 1; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D014158:Transcription, Genetic / Q000187:drug effects / Q000502:physiology*
D000728:Androgens; D057137:DAX-1 Orphan Nuclear Receptor; D004268:DNA-Binding Proteins; D051717:Fushi Tarazu Transcription Factors; D050993:GATA6 Transcription Factor; C494759:GATA6 protein, human; D018398:Homeodomain Proteins; C539965:NR0B1 protein, human; C515057:NR5A1 protein, human; D012333:RNA, Messenger; D018160:Receptors, Cytoplasmic and Nuclear; D018168:Receptors, Retinoic Acid; D012097:Repressor Proteins; D054339:Steroidogenic Factor 1; D014157:Transcription Factors