Circulating miR-1-3p precedes adrenarche and modulates adrenocortical steroidogenesis via protein kinase C signaling.

CONTEXT: Adrenarche involves maturation of the adrenal zona reticularis (ZR), but its molecular regulation is poorly understood. MicroRNAs (miRNAs) may contribute to adrenal development.

OBJECTIVE

To investigate whether circulating miRNAs are associated with ZR maturation during adrenarche and to characterize the functional role of candidate miRNAs in adrenal steroidogenesis.

DESIGN AND

SETTING

Prospective cohort study was nested within the population-based PANIC study with longitudinal follow-up at ages 7, 9, and 15 years, combined with experimental analyses in the human adrenocortical NCI-H295R cell model.

PARTICIPANTS

A total of 34 children (20 girls) with clinical and/or biochemical signs of adrenarche at age 9 as cases, and 24 age-matched controls (11 girls).

INTERVENTIONS: None.

MAIN OUTCOME MEASURES: Longitudinal serum miRNA expression and in vitro effects of candidate miRNAs on adrenal steroidogenesis and gene expression.

RESULTS

Serum miR-1-3p levels were higher in cases compared to controls at age 7 years (fold change 2, p < 0.001), preceding clinical adrenarche. In both groups, miR-1-3p levels declined during adrenarchal and pubertal development. In vitro, miR-1-3p overexpression increased steroidogenic activity (approximately 1.5-fold on average) without altering the expression of canonical steroidogenic enzyme genes. Transcriptomic analysis identified 208 upregulated and 140 downregulated genes, including PRKCA, encoding protein kinase C (PKC), enriched in the ZR and involved in steroidogenic signaling.

CONCLUSIONS

Elevated circulating miR-1-3p precedes clinical adrenarche and enhances steroidogenesis in vitro. The temporal decline of circulating miR-1-3p levels and the identification of PKC support a model in which miR-1-3p may contribute to functional maturation of the ZR through modulation of non-canonical intracellular signaling pathways.