Structural basis of disease-causing mutations in hepatocyte nuclear factor 1beta

Area of Science:

• Molecular biology
• Structural biology
• Genetics

Background:

• Hepatocyte Nuclear Factor 1-beta (HNF1beta) is an atypical POU transcription factor essential for liver, pancreas, and kidney development.
• Inheritable mutations in HNF1beta are primary causes of monogenic diabetes and kidney diseases.

Purpose of the Study:

• To determine the crystal structure of the human HNF1beta DNA binding domain complexed with a high-affinity promoter.
• To elucidate the molecular mechanisms underlying HNF1beta function and the structural basis of disease-associated mutations.

Main Methods:

• X-ray crystallography to obtain the HNF1beta-DNA complex structure.
• Mapping disease-causing mutations onto the determined structure.
• Biochemical and functional assays to test the effects of mutations.

Main Results:

• The crystal structure of the human HNF1beta DNA binding domain in complex with its promoter was determined.
• Disease-causing mutations were localized on the structure, and their functional impact was experimentally validated.
• Comparative analysis with HNF1alpha provided insights into promoter recognition.

Conclusions:

• The study provides a structural basis for understanding HNF1beta's role in gene regulation.
• It clarifies how specific mutations disrupt HNF1beta function, leading to diabetes and kidney diseases.
• This structural information is vital for understanding atypical POU transcription factor mechanisms.