Angiotensin-II acute regulation of rapid response genes in human, bovine, and rat adrenocortical cells

Abstract

Angiotensin-II (Ang-II) regulates adrenal steroid production and gene transcription through several signaling pathways. Changes in gene transcription occur within minutes after Ang-II stimulation, causing an increase in aldosterone production and subsequent increase in the overall capacity to produce aldosterone. Our goal was to compare the Ang-II regulation of early gene expression and confirm the up-regulation of selected genes using quantitative real-time RT-PCR (qPCR) across three species, such as, human, bovine, and rat. Microarray analyses were performed using samples from control and Ang-II (10 nM)-treated (1 h) cells from human adrenocortical tumor cell line H295R, and primary adrenal glomerulosa cells from bovine and rat, applied respectively to human, bovine, and rat chips. qPCR was performed to confirm up-regulation of selected genes using mRNA. The microarray comparison revealed 18% similarity among the top 50 up-regulated genes, with human/rat, 20%; human/bovine, 36%; and rat/bovine, 26% similarity. The gene list generated by this comparison included: activating transcription factor 3, B-cell translocation gene (BTG2), Nuclear receptor subfamily 4, group A, member 1 (NR4A1), NR4A2, NR4A3, early growth response 1, v-fos FBJ murine osteosarcoma viral oncogene homolog (c-FOS), FOSB, and Jun family member B (JUNB). Pretreatment of H295R cells with cycloheximide had no effect on Ang-II induction of these genes, suggesting that they are direct targets of Ang-II signaling. The Ang-II gene targets have been defined in three different adrenocortical model systems. Several of the listed genes have previously been described as being key regulators of adrenocortical function. The presence of adrenal cell common genes in such distinct cell models strengthens the hypothesis that these genes are regulators of aldosterone production.

The AP-1 family member FOS blocks transcriptional activity of the nuclear receptor steroidogenic factor 1

“…Herein, we further determine the downstream signaling events that inhibit CYP17. Based on previous observations indicating FOS as a rapid-response gene activated by Ang II (Nogueira et al, 2007), and on the observation that protein synthesis was needed for TPA inhibition of CYP17, we wanted to determine if FOS induction could be dependent on PKC activation. Our microarray analysis and time- course study revealed the ability of TPA, as well as of Ang II, to induce elevated FOS expression levels.…”

“…These data indicated that the synthesis of new proteins is required for TPA-mediated inhibition of CYP17. We have previously shown that Ang II mediates FOS induction in adrenal cells (Nogueira et al, 2007). Because PKC is activated by Ang II after binding its receptor, we proposed that FOS could also be a factor regulated by TPA.…”

“…Ang II also stimulates expression of the activator protein 1 (AP-1) family members (Nogueira et al, 2007). FOS belongs to the AP-1 family of transcription factors (Curran and Franza, 1988), which include FOS members (FOS, FOSB, Fra-1 and Fra-2) and JUN members (JUN, JUNB and JUND).…”

“…Most AP-1 transcription factors are present at low levels in cells but are rapidly induced and activated in response to specific stimuli. Ang II has been shown to increase FOS expression in primary cultures of rat, bovine and ovine adrenal cells (Viard et al, 1992;Clark et al, 1992), as well as in human adrenocortical tumor cell line H295R (Nogueira et al, 2007). A role for FOS in controlling steroidogenesis in the adrenal gland has been investigated, analyzing its ability to control transcription of steroidogenic acute regulatory (StAR) protein in mouse (Shea-Eaton et al, 2002) and bovine adrenal cells (Rincon Garriz et al, 2009).…”

Stimulus-selective induction of the orphan nuclear receptor NGFIB underlies different influences of angiotensin II and potassium on the human adrenal gland zona glomerulosa-specific 3β-HSD isoform gene expression in adrenocortical H295R cells

“…It has been well established that AngII can stimulate mRNA expression of NGFIB, NURR1, and NOR1 [5,18,19]. However, K + responsiveness of this gene family remains unclear [20,21].…”