Endocrine Abstracts

Many cases of hypertension are associated with inappropriately high levels of aldosterone secretion and it has been proposed that microRNAs play a role in this dysregulation. Previously, we showed that microRNAs expressed within the adrenal cortex significantly repress aldosterone production. Furthermore, stimulation of aldosterone secretion by three different means in the H295R cell line – the most commonly-used in vitro model of the human adrenal cortex – resulted in consistent changes to the microRNA profile of these cells. These profiles were subjected to bioinformatic analysis in order to predict which biological pathways are targeted by these differentially-expressed. Here we present some of those results.

Analysis centred on microRNA derived from H295R cells (n=3/group) incubated for 24 h with either 100 nM angiotensin II (AngII), 10 mM dbcAMP (simulating the effects of ACTH), or 20 mM potassium chloride (KCl). Stimulation of aldosterone synthase (CYP11B2) mRNA levels were confirmed for each treatment. Full microRNA profiles were generated using microarray. Six microRNAs were consistently downregulated across all three treatment types: three are co-transcribed from a cluster on the X chromosome, while two others also come from a single cluster located on chromosome 13; the sixth is transcribed singly from chromosome 14.

Ingenuity Pathway Analysis (IPA) software was used to predict transcripts targeted by these six microRNAs. Only one was predicted to target components of the steroidogenic pathway directly. Further analysis focusing on validated interactions between these microRNAs and specific transcript targets identified effects across a diverse range of biological pathways. These include cell cycle regulation, insulin receptor signalling, and Wnt/β-catenin signalling.

These data suggest that differing methods of aldosterone stimulation result in common effects on specific microRNA levels. Bioinformatic analysis identifies plausible targets for these microRNAs and will aid in the direction of future in vitro studies.