Cistrome of the aldosterone-activated mineralocorticoid receptor in human renal cells

Aldosterone exerts its effects mainly by activating the mineralocorticoid receptor (MR), a transcription factor that regulates gene expression through complex and dynamic interactions with coregulators and transcriptional machinery, leading to fine-tuned control of vectorial ionic transport in the distal nephron. To identify genomewide aldosterone-regulated MR targets in human renal cells, we set up a chromatin immunoprecipitation (ChIP) assay by using a specific anti-MR antibody in a differentiated human renal cell line expressing green fluorescent protein (GFP)-MR. This approach, coupled with highthroughput sequencing, allowed identification of 974 genomic MR targets. Computational analysis identified an MR response element (MRE) including single or multiple half-sites and palindromic motifs in which the AGtA-CAgxatGTtCt sequence was the most prevalent motif. Most genomic MR-binding sites (MBSs) are located >10 kb from the transcriptional start sites of target genes (84%). Specific aldosterone-induced recruitment of MR on the first most relevant genomic sequences was further validated by ChIPquantitative (q)PCR and correlated with concomitant and positive aldosterone-activated transcriptional regulation of the corresponding gene, as assayed by RT-qPCR. It was notable that most MBSs lacked MREs but harbored DNA recognition motifs for other transcription factors (FOX, EGR1, AP1, PAX5) suggesting functional interaction. This work provides new insights into aldosterone MR-mediated renal signaling and opens relevant perspectives for mineralocorticoid-related pathophysiology.-Le Billan, F., Khan, J. A., Lamribet, K., Viengchareun, S., Bouligand, J., Fagart, J., Lombès, M. Cistrome of the aldosterone-activated mineralocorticoid receptor in human renal cells.