ESPE Abstracts

The physiology of adrenarche, i.e. the development of the zona reticularis of the adrenal cortex, is mostly unknow. Some genes of steroidogenic enzymes need to be down- (HSD3B2) while others upregulated (e.g. CYB5) to enhance androgen production in zona reticularis, but it is not known how this is regulated. Micro RNAs (miRNAs) are small non-coding RNAs that can affect gene expression at posttranscriptional level. We hypothesized that miRNAs might be involved in regulating adrenarche and investigated circulating miRNA profiles in a case-control setting before and during adrenarche. Subjects were selected from prepubertal participants of the Finnish PANIC study, and they had been examined longitudinally at ages 6-8 and 9-11 years. Children in the case group (n= 34) had adrenarche at age 9-11 years, while controls (n= 24) had no signs of adrenarche at that age. Adrenarche was defined either by clinical criteria as having at least one clinical sign of adrenarche (pubarche, axillary hair, adult-type body odor, oily hair/skin, acne/comedones) or by biochemical criteria as having serum DHEAS concentration > 1 µmol/L. Circulating small RNAs were extracted from serum with spin-column purification, miRNA libraries were prepared and indexed using QIAGEN kits with 200 bp size selection and sequenced using the Illumina NovaSeq 6000 system with S1 flow cell channel and 72 bp read length. Mapping and calculations of read counts were performed with QIAGENs’ online tool, and differential expression analyses were performed with edgeR and DESeq2 packages. We found that at age 6-8 years (before adrenarche), a total of 3 miRNAs were up- and 5 downregulated in children who later developed signs of adrenarche at age 9-11 years. At adrenarche, 5 miRNAs were up- and 16 downregulated. Most promising candidates include miR-1-3p (upregulated before clinical adrenarche; fold change 1.98), miR-203a-3p (upregulated during adrenarche; fold change 1.48), and miR-20b-5p, miR-486-5p, and miR-16-5p (all downregulated during adrenarche; fold change -1.81, -1.61, and -1.49, respectively). These findings suggest that miRNAs might have a role in adrenarche, and that they could serve as biomarkers. Ongoing functional testing of the effects of these identified candidate miRNAs on steroid hormone biosynthesis might reveal novel mechanistic insights for the regulation of adrenocortical development and steroid production.