Identification of candidate transcriptional regulators of renin using a highly redundant siRNA methodology

Many anti‐hypertensive agents, including inhibitors of the Renin‐Angiotensin (RAS) pathway result in a reactive rise in circulating renin levels that may blunt the therapeutic response to these agents. This is partly due to the interruption of negative feedback by Ang II on the renin secreting cells within the juxtaglomerular (JG) apparatus in the kidney. To identify potential regulators of renin transcription and secretion that would obviate this rise in renin, a highly redundant siRNA experiment was performed in Calu‐6 cells, a cell line that recapitulates aspects of JG cell biology. 58 candidate renin regulators identified in an initial whole genome siRNA renin‐secretion screen were evaluated by monitoring renin transcription, secretion and target knockdown after transfection of five distinct siRNAs for each target. Stringent criteria were used to identify 11 regulators of renin, including (a) previously reported regulators of renin secretion, such as components of the cAMP pathway and PPARγ, and (b) a novel regulatory role for TGF‐β and genes in the nucleotide salvage pathway. A subset of the hits were further confirmed with pharmacological probes in Calu‐6 cells and other cell‐based models of renin secretion. This study suggests that interrogation of the Calu‐6 cell‐based system can help identify novel upstream targets in the RAS pathway that, when manipulated, do not result in a reactive rise in renin.