The role of the mineralocorticoid receptor in adipocyte biology and fat metabolism

Aldosterone controls blood pressure by binding to the mineralocorticoid receptor (MR), a ligand-activated transcription factor which regulates critical genes controlling salt and water homeostasis in the kidney. In recent years, inappropriate MR activation has been shown to trigger deleterious responses in various tissues, including vessels, heart and brain, hence promoting vascular inflammation, cardiovascular remodeling, endothelial dysfunction, and oxidative stress. Moreover, epidemiological studies have shown a clear association between aldosterone levels and the incidence of metabolic syndrome. In particular, recent work has revealed functional MRs in adipose tissue, where they mediate the effects of aldosterone and glucocorticoids, displaying important and specific functions involving adipose differentiation, expansion and proinflammatory capacity. This recent evidence finally moved MR out of the shadow of the glucocorticoid receptor (GR), which had previously been considered the only player mediating corticosteroid action in adipose tissue. This has opened a new era of research focusing on the complexity and selectivity of MR function in adipocyte biology. The aim of this review is to summarize the latest concepts on the role of MR in white and brown adipocytes, and to discuss the potential benefits of tissue-selective MR blockade in the treatment of obesity and metabolic syndrome.