GATA-6 Is Expressed in the Human Adrenal and Regulates Transcription of Genes Required for Adrenal Androgen Biosynthesis

Patricia Jimenez, Karla Saner, Bobbie Mayhew, William E. Rainey
2003 Endocrinology  
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 semi-quantitative RTPCR we found 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
more » ... regulatory protein (StAR), cholesterol side-chain cleavage (CYP11A), 17αhydroxylase (CYP17), and DHEA-sulfotransferase (SULT2A1) were co-transfected with an expression vector containing GATA-6 into adrenal NCI-H295R cells and non-steroidogenic 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 if 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 opposes SF1 activated transcription of many genes and abolished the GATA-6/SF1 ability to increase reporter activity. These results suggest the adrenal uses GATA-6 to enhance transcription of steroidmetabolizing enzymes needed to produce DHEA-S. Additionally, GATA-6 works in synergy with SF1 to maximally increase expression of enzymes needed to produce adrenal androgens.
doi:10.1210/en.2003-0472 pmid:12959982 fatcat:vf35eganqre6fhht3r7fh7car4