Transcriptional activator that regulates the tissue specific expression of multiple genes, especially in pancreatic islet cells and in liver. Required for the expression of several liver specific genes. Binds to the inverted palindrome 5'- GTTAATNATTAAC-3'. Defects in HNF1A are a cause of hepatic adenomas familial (HEPAF). Hepatic adenomas are rare benign liver tumors of presumable epithelial origin that develop in an otherwise normal liver. Hepatic adenomas may be single or multiple. They consist of sheets of well-differentiated hepatocytes that contain fat and glycogen and can produce bile. Bile ducts or portal areas are absent. Kupffer cells, if present, are reduced in number and are non-functional. Conditions associated with adenomas are insulin-dependent diabetes mellitus and glycogen storage diseases (types 1 and 3). Bi-allelic inactivation of HNF1A, whether sporadic or associated with MODY3, may be an early step in the developmant of some hepatocellular carcinomas. Defects in HNF1A are the cause of maturity-onset diabetes of the young type 3 (MODY3); also symbolized MODY-3. MODY is a form of diabetes that is characterized by an autosomal dominant mode of inheritance, onset in childhood or early adulthood (usually before 25 years of age), a primary defect in insulin secretion and frequent insulin-independence at the beginning of the disease. Defects in HNF1A are the cause of susceptibility to diabetes mellitus insulin-dependent type 20 (IDDM20). IDDM20 is a multifactorial disorder of glucose homeostasis that is characterized by susceptibility to ketoacidosis in the absence of insulin therapy. Clinical fetaures are polydipsia, polyphagia and polyuria which result from hyperglycemia-induced osmotic diuresis and secondary thirst. These features can result in long-term complications that affect the eyes, kidneys, nerves, and blood vessels. Belongs to the HNF1 homeobox family. 3 isoforms of the human protein are produced by alternative splicing. Note: This description may include information from UniProtKB.
Cellular Component: cytoplasm; nucleus; protein complex
Molecular Function: protein binding; protein dimerization activity; transcription factor activity
Biological Process: glucose homeostasis; glucose import; positive regulation of transcription from RNA polymerase II promoter; positive regulation of transcription, DNA-dependent; regulation of transcription from RNA polymerase II promoter