Brown fat–generated microRNAs map an inter-organ metabolic circuit via secreted carriers

Using brown-fat–specific 4-thiouracil labelling, researchers traced how brown fat secretes microRNAs in vesicles and protein-bound forms that are selectively taken up by liver, muscle, and hypothalamus. In recipient tissues these BAT-derived miRNAs enter Ago2–RISC and regulate metabolic pathways (notably miR-1a-3p targeting FoxO1 in muscle, affecting mitochondrial function). Deleting Dicer in BAT reduces circulating BAT miRNAs and disrupts tissue metabolism, revealing a defined endocrine network whereby brown fat communicates with distant organs to modulate energy homeostasis.