Expression of Long Non‐Coding RNAs is Regulated by Aldosterone in Kidney Distal Nephron Epithelia

Abstract

The steroid hormone, aldosterone is a well‐characterized and essential mediator of sodium (Na+) homeostasis. A decrease in blood Na+ concentration elicits the release of aldosterone, which exerts its impact by increasing Na+ transport in the epithelial cells of the kidney distal nephron. Upregulation of transepithelial Na+ transport through both genomic and non‐genomic aldosterone actions, resets Na+ balance. The genomic response to aldosterone is best described for protein coding genes that have been classed into aldosterone‐induced or repressed proteins. Acting in concert these proteins maintain Na+ homeostasis. Less well characterized are non‐coding RNAs that respond to aldosterone stimulation. While a role for microRNAs in aldosterone action has recently been recognized, there is little information about lncRNAs and the ability for aldosterone to alter their expression.Here we examined the potential for long non‐coding RNAs (lncRNAs) to be regulated by aldosterone as a potentially novel intermediary in the aldosterone signaling cascade. Mouse cortical collecting duct (mCCD‐cl1) epithelial cells, grown on filter supports, were stimulated with aldosterone (50nM, 6hrs) and total RNA collected from 10 biological replicates. The expression of ~22 000 validated and predicted lncRNA was determined by microarray (arraystar). From the raw intensity data, a significant difference was detected in 219 transcripts, with 169 lncRNAs upregulated and 50 downregulated in response to aldosterone stimulation (>100%, p<0.05). No significant change in lncRNA expression was observed for ~21 000 transcripts. When array intensities were normalized and corrected internally, 18 lncRNAs exhibited >150% increase in expression (p<0.05) following aldosterone stimulation compared to unstimulated controls (n=5 paired samples). Changes in lncRNA transcripts were validated by qPCR and the most significantly altered lncRNA tested was a non‐coding retrained intron (ENSMUST00000144044) that increased 2.5 fold after 6hr aldosterone stimulation. A time‐course of aldosterone stimulation demonstrated that this transcript was further upregulated and had significantly increased expression 4.4 fold (n=4) after 24hrs of aldosterone stimulation. The lncRNA transcript was synthesized into an expression vector by Gibson assembly to drive the constitutive over‐expression of this transcript in mCCD cells. Cells overexpressing the lncRNA, in the absence of aldosterone stimulation, had altered ENaC‐mediated Na+ transport compared to control cells. The mechanism of the lncRNA action has yet to be elucidated.These data provide the first example of lncRNA expression changes in response to aldosterone that may play a role in altering Na+ transport in epithelial cells of the distal nephron.Support or Funding InformationThis work is supported by the NIH (NIDDK DK10284 to MBB)This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.