Endocrine functions of bile acids

Bile acids (BAs), a group of structurally diverse molecules that are primarily synthesized in the liver from cholesterol, are the chief components of bile. Besides their well‐established roles in dietary lipid absorption and cholesterol homeostasis, it has recently emerged that BAs are also signaling molecules, with systemic endocrine functions. BAs activate mitogen‐activated protein kinase pathways, are ligands for the G‐protein‐coupled receptor TGR5, and activate nuclear hormone receptors such as farnesoid X receptor α. Through activation of these diverse signaling pathways, BAs can regulate their own enterohepatic circulation, but also triglyceride, cholesterol, energy, and glucose homeostasis. Thus, BA‐controlled signaling pathways are promising novel drug targets to treat common metabolic diseases, such as obesity, type II diabetes, hyperlipidemia, and atherosclerosis.