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

• Published in: Human molecular genetics Vol. 10; no. 19; pp. 2089 - 2097
• Main Authors: THOMAS, Heike, JASCHKOWITZ, Karin, HATTERSLEY, Andrew T, BULMAN, Mike, FRAYLING, Timothy M, MITCHELL, Simon M. S, ROOSEN, Simone, LINGOTT-FRIEG, Anja, TACK, Cees J, ELLARD, Sian, RYFFEL, Gerhart U
• Format: Journal Article
• Language: English
• Published: Oxford Oxford University Press 15.09.2001
• Subjects: Biological and medical sciences; Fundamental and applied biological sciences. Psychology; HNF-1^a gene; HNF-4^a gene; IPF-1 gene; Molecular and cellular biology
• ISSN: 0964-6906; 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-4 alpha (MODY1), HNF-1 alpha (MODY3), IPF-1 (also known as PDX-1, MODY4) and HNF-1 beta (MODY5). Analyzing the transcription of the HNF-4 alpha 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-1 alpha , HNF-1 beta 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-4 alpha 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-4 alpha gene.