Extracellular miRNAs: From Biomarkers to Mediators of Physiology and Disease

Abstract

miRNAs can be found in serum and other body fluids and serve as biomarkers for disease. More importantly, secreted miRNAs, especially those in extracellular vesicles (EVs) such as exosomes, may mediate paracrine and endocrine communication between different tissues and thus modulate gene expression and the function of distal cells. When impaired, these processes can lead to tissue dysfunction, aging and disease. Adipose tissue is an especially important contributor to the pool of circulating exosomal miRNAs. As a result, alterations in adipose tissue mass or function, which occur in many metabolic conditions, can lead to changes in circulating miRNAs which then function systemically. Here we review the findings that led to these conclusions and discuss how this sets the stage for new lines of investigation in which extracellular miRNAs are recognized as important mediators of intercellular communication and potential candidates for therapy of disease. In this Review, Mori et al. discuss the emerging literature of extracellular miRNAs as mediators of tissue crosstalk. They outline the ability of these miRNAs to act as effective biomarkers, as well as a new class of hormones, and thus their potential as monitors of and therapeutic agents for disease.