Mineralocorticoid and glucocorticoid receptors are closely related steroid hormone receptors that regulate gene expression through many of the same hormone response elements. However, their transcriptional activities and effects in skeletal muscles are largely unknown. We recently identified mineralocorticoid receptors (MR) in skeletal muscles after finding that combined treatment with the angiotensin-converting enzyme inhibitor lisinopril and MR antagonist spironolactone was therapeutic in Duchenne muscular dystrophy mouse models. The glucocorticoid receptor (GR) agonist prednisolone is the current standard-of-care treatment for Duchenne muscular dystrophy because it prolongs ambulation, likely due to its anti-inflammatory effects. However, data on whether glucocorticoids have a beneficial or detrimental direct effect on skeletal muscle are controversial. Here, we begin to define the gene expression profiles in normal differentiated human skeletal muscle myotubes treated with MR and GR agonists and antagonists. The MR agonist aldosterone and GR agonist prednisolone had highly overlapping gene expression profiles, supporting the notion that prednisolone acts as both a GR and MR agonist that may have detrimental effects on skeletal muscles. Co-incubations with aldosterone plus either nonspecific or selective MR antagonists, spironolactone or eplerenone, resulted in similar numbers of gene expression changes, suggesting that both drugs can block MR activation to a similar extent. Eplerenone treatment alone decreased a number of important muscle-specific genes. This information may be used to develop biomarkers to monitor clinical efficacy of MR antagonists or GR agonists in muscular dystrophy, develop a temporally coordinated treatment with both drugs, or identify novel therapeutics with more specific downstream targets.
In vitro degradation of the Duchenne muscular dystrophy gene product (dystrophin)
