Structure/Function Studies of Hepatocyte Nuclear Factor-1α, a Diabetes-Associated Transcription Factor

Abstract

Mutations in the transcription factor hepatocyte nuclear factor-1α (HNF-1α) cause maturity-onset diabetes of the young type 3 (MODY3), a form of diabetes mellitus characterized by autosomal dominant inheritance, early onset, and pancreatic β-cell dysfunction. We have examined the effects of five diabetes-associated mutations (L12H, G191D, R263C, P379fsdelCT, and L584S585fsinsTC) on HNF-1α function including DNA binding ability, intracellular localization, and transactivation activity. L12H, P379fsdelCT, and L584S585fsinsTC mutations were found in patients with a clinical diagnosis of MODY, while G191D and R263C mutations were identified in patients diagnosed with type 2 diabetes. These mutations had diverse effects on the functional properties of HNF-1α. Comparison of the functional data with clinical information suggested that transactivation activity of mutant HNF-1α in β cells like MIN6 may be the primary determinants of the phenotypic differences observed among diabetic patients with HNF-1α mutations.