RNA Decay Controls the Kinetics of the Angiotensin II Gene Expression Response

Complex cellular resonses require the temporal coordination of stimulus-induced gene expression programs. Angiotensin II (AngII) is the active 8 amino acid peptide in the renin-angiotensin-aldosterone system that controls blood pressure and fluid balance. AngII binds to type I angiotensin receptor in the adrenal cortex to initiate a cascade of temporally coordinated events leading to the production of aldosterone, a master regulator of blood pressure and volume. We stimulated a steroidogenic human cell line (H295R) with AngII and performed RNA-seq at twelve points. We identified twelve distict temporally distinct groups of gene expression responses each encoding functionally related proteins important for various steps of aldosterone productionl. Interstingly, the shape of the impulse response suggested a key role for RNA decay. Indeed, RNA decay rates in unstimulated H295R cells strongly correlated with the amplitude and peakiness of the gene expression response for each group of genes. We also found evidence for increases in RNA decay during the AngII response. Next, we selected candidate RBPs based on motif finding, adrenal specific expression, and AngII responsiveness. We performed an siRNA knockdown screen on these 22 candidates to identify RBPs that regulate aldosterone levels. Eight of these RBPs exhibited statistically significant changes in aldosterone for at least two independent siRNAs. Interestingly, multiple RBPs that promote RNA decay were found to suppress aldosterone production and induced in response to AngII-stimulation. These RBPs could be responsible for our observed increases in RNA decay. Altogether, these data support a model in which RNA decay is a critical regulator of the timing and strength of AngII-induced gene expression and ultimately aldosterone production.