HNF4α (Hepatocyte Nuclear Factor 4 alpha) is a member of the HNF family, a nuclear receptor protein that regulates gene expression by binding to DNA. It is primarily expressed in tissues such as the liver, intestines, pancreas, and kidneys, playing a crucial role in the regulation of glucose and lipid metabolism. HNF4α consists of multiple structural domains, including a DNA-binding domain and a ligand-binding domain, capable of responding to intracellular signals and affecting various physiological processes, including insulin sensitivity and bile acid metabolism. The tissue-specific expression and functional mutations of HNF4α are closely associated with various diseases, including diabetes, inflammatory bowel disease, and liver diseases.