Endocrine Abstracts

MicroRNAs (miRs) are a subset of small RNA molecules that regulate gene expression post-transcriptionally. Little is known about the expression and the role of miRs in the adrenal gland. Thus, we determined the miRs expression pattern under baseline conditions and 10, 30 and 60 min after ACTH stimulation test in mice adrenal glands using miRs microarray. The miRs expression profile of adrenals obtained from the array was bioinformatically analyzed to indentify miRs that putatively target important genes. After selecting 20 miRs, with a significant change in their expression level upon ACTH stimulation test, it was found that four of these miRs putatively target the glucocorticoid receptor (GR, Nr3c1): miR96, miR101a, miR142-3p, miR433, in addition to miR18a, which is already known from previous studies to influence GR expression in the brain. The array data could be confirmed with real-time PCR analysis showing an upregulation of miR96 10 min after ACTH test (baseline: 100±27%, 10 min post ACTH: 244±18%, P<0.05), and also of mir433 in all investigated timepoints (baseline: 100±22%, 10 min: 197±24%, 30 min: 168±14%, 60 min: 163±9%, P<0.05). Furthermore, a decrease of miR142 expression was found 30 min (100±29%, 30 min: 20±8%, P<0.05) and of miR101 10 min after ACTH stimulation test (baseline: 100±20%, 10 min: 20±1%, P<0.05). GR expression measured with real-time PCR was elevated 10 min after ACTH stimulation (144±19%) in comparison to the control group (100±10%, P<0.05). Targeting predictions of these four miRs GR 3′UTR was further tested by in vitro luciferase assays. Preliminary data show that miR96, miR101a and miR142 target the GR 3′UTR region and result in a 20–40% decreased mRNA level of GR 3′UTR. Thus, ACTH stimulation influences short term expression of different miRs and the GR; at least, three miRs, mir96, mir101a and miR142, regulate the GR expression post-transcriptionally. The impact of this regulation in physiological stress response awaits further investigation.