Aldosterone alters the chromatin structure of the murine endothelin-1 gene

Abstract

Aldosterone increases sodium reabsorption in the renal collecting duct and systemic blood pressure. Paradoxically, aldosterone also induces transcription of the endothelin-1 (Edn1) gene to increase protein (ET-1) levels, which inhibits sodium reabsorption. Aims Here we investigated changes in the chromatin structure of the Edn1 gene of collecting duct cell lines in response to aldosterone treatment. The Edn1 gene has a CpG island that encompasses the transcription start site and four sites in the 5’ regulatory region previously linked to transcriptional regulation. Materials and methods The chromatin structure of the Edn1 gene was investigated using a quantitative PCR-based DNaseI hypersensitivity assay in murine hepatocyte (AML12), renal cortical collecting duct (mpkCCDC14), outer medullary collecting duct1 (OMCD1), and inner medullary collecting duct-3 (IMCD-3) cell lines. Key findings The CpG island was uniformly accessible. One calcium-responsive NFAT element remained at low chromatin accessibility in all cell lines under all conditions tested. However, the second calcium responsive NFAT element located at −1563 bp upstream became markedly more accessible in IMCD-3 cells exposed to aldosterone. Importantly, one established aldosterone hormone response element HRE at −671 bp relative to the transcription start site was highly accessible, and another HRE (− 551 bp) became more accessible in aldosterone-treated IMCD-3 and OMCD1 cells. Significance The evidence supports a model in which aldosterone activation of the mineralocorticoid receptor (MR) results in the MR-hormone complex binding at HRE at −671 bp to open chromatin structure around other regulatory elements in the Edn1 gene.

COMMD10 Regulates Endosomal Recycling of Epithelial Sodium Channel (ENaC)

“…Analysis of mRNA levels of COMMDs in 300 nM aldosterone treated cells revealed that aldosterone does not change the mRNA levels of any of COMMD1-10 (RQ values were not beyond 0.5 and 2) at any time period (Figure 4I) suggesting the reduction in protein levels of COMMDs by aldosterone is not linked with changes in mRNA levels. However, SGK1 mRNA levels (a positive control for aldosterone treatment) were significantly increased at each time period (30 min: 1 for vehicle vs 3.82±2.45 for aldo-treated epithelia; 3 hours: 1 for vehicle vs 33.58±10.28 for aldo-treated epithelia; 24 hours: 1 for vehicle vs 48.12±11.23 for aldo-treated epithelia, Figure 4J) consistent with previous reports (Náray-Fejes-Tóth et al ., 1999; Jacobs et al ., 2016; Welch et al ., 2016).…”