A Cardiac MicroRNA Governs Systemic Energy Homeostasis by Regulation of MED13

SummaryObesity, type 2 diabetes, and heart failure are associated with aberrant cardiac metabolism. We show that the heart regulates systemic energy homeostasis via MED13, a subunit of the Mediator complex, which controls transcription by thyroid hormone and other nuclear hormone receptors. MED13, in turn, is negatively regulated by a heart-specific microRNA, miR-208a. Cardiac-specific overexpression of MED13 or pharmacologic inhibition of miR-208a in mice confers resistance to high-fat diet-induced obesity and improves systemic insulin sensitivity and glucose tolerance. Conversely, genetic deletion of MED13 specifically in cardiomyocytes enhances obesity in response to high-fat diet and exacerbates metabolic syndrome. The metabolic actions of MED13 result from increased energy expenditure and regulation of numerous genes involved in energy balance in the heart. These findings reveal a role of the heart in systemic metabolic control and point to MED13 and miR-208a as potential therapeutic targets for metabolic disorders.PaperCli

Control of whole body energy homeostasis by microRNA regulation

The disclosure provides a method of regulating fatty acid or glucose metabolism in a cell by contacting the cell with a modulator of miR-208a and/or miR-208b activity or expression. The disclosure also provides a method of treating or preventing a metabolic disorder, such as obesity, diabetes, or metabolic syndrome, in a subject by administering to the subject an inhibitor of miR-208a and/or miR-208b activity or expression. Also provided is a method of enhancing or improving mitochondrial function and/or redox-homeostasis in a subject by administering to the subject an inhibitor of miR-208a and/or miR-208b activity or expression.Board of Regents, University of Texas Syste

MED13‐dependent signaling from the heart confers leanness by enhancing metabolism in adipose tissue and liver

Abstract The heart requires a continuous supply of energy but has little capacity for energy storage and thus relies on exogenous metabolic sources. We previously showed that cardiac MED13 modulates systemic energy homeostasis in mice. Here, we sought to define the extra‐cardiac tissue(s) that respond to cardiac MED13 signaling. We show that cardiac overexpression of MED13 in transgenic (MED13cTg) mice confers a lean phenotype that is associated with increased lipid uptake, beta‐oxidation and mitochondrial content in white adipose tissue (WAT) and liver. Cardiac expression of MED13 decreases metabolic gene expression in the heart but enhances them in WAT. Although exhibiting increased energy expenditure in the fed state, MED13cTg mice metabolically adapt to fasting. Furthermore, MED13cTg hearts oxidize fuel that is readily available, rendering them more efficient in the fed state. Parabiosis experiments in which circulations of wild‐type and MED13cTg mice are joined, reveal that circulating factor(s) in MED13cTg mice promote enhanced metabolism and leanness. These findings demonstrate that MED13 acts within the heart to promote systemic energy expenditure in extra‐cardiac energy depots and point to an unexplored metabolic communication system between the heart and other tissues