miR-125b affects mitochondrial biogenesis and impairs brite adipocyte formation and function

• miR-125b-5p levels negatively correlate with UCP1 expression in rodent and human.
• miR125b levels in white adipose tissue are positively correlated with BMI.
• miR-125b-5p modulates oxygen consumption.
• Mitochondriogenesis is controlled by miR-125b-5p.
• In vivo modulation of miR-125b-5p controls brown and brite adipocyte formation.

ObjectiveIn rodents and humans, besides brown adipose tissue (BAT), islands of thermogenic adipocytes, termed “brite” (brown-in-white) or beige adipocytes, emerge within white adipose tissue (WAT) after cold exposure or β3-adrenoceptor stimulation, which may protect from obesity and associated diseases. microRNAs are novel modulators of adipose tissue development and function. The purpose of this work was to characterize the role of microRNAs in the control of brite adipocyte formation.Methods/ResultsUsing human multipotent adipose derived stem cells, we identified miR-125b-5p as downregulated upon brite adipocyte formation. In humans and rodents, miR-125b-5p expression was lower in BAT than in WAT. In vitro, overexpression and knockdown of miR-125b-5p decreased and increased mitochondrial biogenesis, respectively. In vivo, miR-125b-5p levels were downregulated in subcutaneous WAT and interscapular BAT upon β3-adrenergic receptor stimulation. Injections of an miR-125b-5p mimic and LNA inhibitor directly into WAT inhibited and increased β3-adrenoceptor-mediated induction of UCP1, respectively, and mitochondrial brite adipocyte marker expression and mitochondriogenesis.ConclusionCollectively, our results demonstrate that miR-125b-5p plays an important role in the repression of brite adipocyte function by modulating oxygen consumption and mitochondrial gene expression.