A distant upstream promoter of the HNF-4alpha gene connects the transcription factors involved in maturity-onset diabetes of the young

• Published in: Human molecular genetics 2001-09, Vol.10 (19), p.2089-2097
• Main Authors: Thomas, H, Jaschkowitz, K, Bulman, M, Frayling, T M, Mitchell, S M, Roosen, S, Lingott-Frieg, A, Tack, C J, Ellard, S, Ryffel, G U, Hattersley, A T
• Format: Article
• Language: English
• Subjects: Adult; Animals; Base Sequence; Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; Diabetes Mellitus, Type 2 - genetics; DNA Primers - chemistry; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; Electrophoretic Mobility Shift Assay; Female; Hepatocyte Nuclear Factor 4; Homeodomain Proteins; Humans; In Vitro Techniques; Islets of Langerhans - metabolism; Luciferases - metabolism; Male; Mice; Middle Aged; Molecular Sequence Data; Mutation; Pedigree; Phosphoproteins - genetics; Promoter Regions, Genetic; Reverse Transcriptase Polymerase Chain Reaction; Trans-Activators - metabolism; Transcription Factors - genetics; Tumor Cells, Cultured - physiology
• ISSN: 0964-6906; 1460-2083; 1460-2083
• DOI: 10.1093/hmg/10.19.2089

Maturity-onset diabetes of the young (MODY) is a monogenic, autosomal dominant subtype of early-onset diabetes mellitus due to defective insulin secretion by the pancreatic beta-cell in humans. Five different genes have been identified including those encoding the tissue-specific transcription factors expressed in pancreatic beta-cells, i.e. HNF-4alpha (MODY1), HNF-1alpha (MODY3), IPF-1 (also known as PDX-1, MODY4) and HNF-1beta (MODY5). Analyzing the transcription of the HNF-4alpha gene, we now identify an alternative promoter, P2, which is 46 kb 5' to the previously identified P1 promoter of the human gene. Based on RT-PCR this distant upstream P2 promoter represents the major transcription site in pancreatic beta-cells, but is also used in hepatic cells. Transfection assays with various deletions and mutants of the P2 promoter reveal functional binding sites for HNF-1alpha, HNF-1beta and IPF-1, the other transcription factors known to encode MODY genes. We demonstrate the significance of this alternative promoter in a large MODY family where a mutated IPF-1 binding site in the P2 promoter of the HNF-4alpha gene co-segregates with diabetes (LOD score 3.25). These data suggest a regulatory network of the four MODY transcription factors interconnected at the distant upstream P2 promoter of the HNF-4alpha gene.