Expression of miRNA in obesity and insulin resistance: a review.

MicroRNAs (miRNAs) are part of the epigenetic mechanisms that regulate gene expression at a post-transcriptional level. This review describes some miRNAs whose expression is modified in obesity and that may be involved in the development of insulin resistance. The metabolic alterations associated with obesity are due to an adipose tissue dysfunction. miRNAs are a mechanism that regulates gene expression, one miRNA can regulate the expression up to a thousand genes, and at the same time one gene can be regulated by several miRNAs; moreover, miRNA expression is tissue specific. Obesity leads to a dysregulation of miRNA expression in adipose tissue, and changes in miRNA expression relate to changes in gene expression related to the development of insulin resistance. However, because miRNA can be exported to the extracellular medium through exosomes, proteins, and lipoproteins, miRNA can be found in extracellular fluids like blood, urine, saliva, and cerebrospinal fluid. Considering the above, miRNA have been proposed as biological markers of different diseases, and also as potential therapeutic targets.