Profile of mineralocorticoid receptor-dependent transcriptome from the mouse aldosterone-sensitive distal nephron

The mineralocorticoid receptor (MR, Nr3c2) is responsible for aldosterone-regulation of Na+ and K+ balance and blood pressure. We apply RNA-Seq and bioinformatic approaches in isolated tubule segments of MR KO vs. Control mice to understand how aldosterone activates electrogenic Na+- K+ exchange in the aldosterone sensitive distal nephron (ASDN), including connecting tubule and cortical collecting duct tubule. MR-flox/Pax8‐rtTA/LC1 mice were used as a doxycycline (DOX)-inducible Nr3c2 gene KO model. After DOX treatment, four groups were prepared to distinguish between K+ and MR effects: 1) control mice on normal K+ diet (CT-NK) or 2) high K+ diet (CT-HK) and 3) MR knockout mice on normal K+ diet (KO-NK) or 4) low K+ diet (KO-LK). RNA-Seq analysis was carried out in the microdissected connecting tubule and cortical collecting duct tubule segments (5-6 mice per group and ~10 fresh ASDN tubules per mouse). Differential expression (DE) genes were identified (FDR< 0.05) and used for further bioinformatic analyses. DE genes were identified from comparisons of MR KO-NK vs. CT-NK and MR KO-LK vs. CT-HK, respectively. Absence of transcripts on the third exon of Nr3c2 gene confirmed complete disruption of Nr3c2 gene in the MR KO. All known aldosterone-response genes were significantly decreased in MR KO-LK compared to CT-HK. Our data provide a comprehensive MR-dependent transcriptomic profile of the ASDN isolated from the kidney.