Adrenal transcription regulatory genes modulated by angiotensin II and their role in steroidogenesis

Abstract

Transcription regulatory genes are crucial modulators of cell physiology and metabolism whose intracellular levels are tightly controlled to respond to extracellular stimuli. We studied transcription regulatory genes modulated by angiotensin II, one of the most important regulators of adrenal cortical cell function, and their role in adrenal steroidogenesis in H295R human adrenocortical cells. Angiotensin II-modulated transcription regulatory genes were identified with high-density oligonucleotide microarrays and the results validated by real-time RT-PCR. Cotransfection reporter assays were performed in H295R cells to analyze the role of these transcription regulatory genes in the control of the expression of 11beta-hydroxylase and aldosterone synthase, the last and unique enzymes of the glucocorticoid and mineralocorticoid biosynthetic pathways, respectively. We selected a subset of the most regulated genes for reporter plasmid studies to determine the effect on these enzymes. BHLHB2, BTG2, and SALL1 decreased expression of both enzymes, whereas CITED2, EGR2, ELL2, FOS, FOSB, HDAC5, MAFF, MITF, NFIL3, NR4A1, NR4A2, NR4A3, PER1, and VDR increased expression for both enzymes. By the ratio of aldosterone synthase to 11beta-hydroxylase expression, NFIL3, NR4A1, NR4A2, and NR4A3 show the greatest selectivity toward upregulating expression of the mineralocorticoid biosynthetic pathway preferentially. In summary, this study reports for the first time a set of transcription regulatory genes that are modulated by angiotensin II and their role in adrenal gland steroidogenesis. Abnormal regulation of the mineralocorticoid or glucocorticoid biosynthesis pathways is involved in several pathophysiological conditions; hence the modulated transcription regulatory genes described may correlate with adrenal steroidogenesis pathologies.