Major signaling pathways involved in the regulation of brown and beige adipose tissue activity. Abbreviations: β-Adrenergic Receptor (β-AR), CCAAT-enhancer-binding proteins (C/EBP), cyclic adenosine monophosphate (cAMP), cAMP-response element binding protein (CREB), Type II iodothyronine deiodinase (DIO2), peroxisome proliferator-activated receptor gamma coactivator 1-α (PGC1α), peroxisome proliferator-activated receptor (PPAR), triiodothyronine (T3), thyroxine (T4), G-protein-coupled bile acid receptor (TGR5), thyroid receptor (TR).