Novel monogenic diabetes mutations in the P2 promoter of the HNF4A gene are associated with impaired function in vitro

Institut für Zellbiologie (Tumorforschung), Universitätsklinikum Essen, Universität Duisburg-Essen, Germany.
Diabetic Medicine (Impact Factor: 3.12). 06/2010; 27(6):631-5. DOI: 10.1111/j.1464-5491.2010.03003.x
Source: PubMed


Mutations in HNF4A cause a form of monogenic beta-cell diabetes. We aimed to identify mutations in the pancreas-specific P2 promoter of HNF4A in families with suspected HNF4A diabetes and to show that they impaired the function of the promoter in vitro.
We screened families with a clinical suspicion of HNF4A monogenic beta-cell diabetes for mutations in the HNF4A P2 promoter. We investigated the function of the previously reported HNF4A P2 promoter mutation -192C>G linked to late-onset diabetes in several families, along with two new segregating mutations, in vitro using a modified luciferase reporter assay system with enhanced sensitivity.
We identified two novel HNF4A P2 promoter mutations that co-segregate with diabetes in two families, -136A>G and -169C>T. Both families displayed phenotypes typical of HNF4A monogenic beta-cell diabetes, including at least two affected generations, good response to sulphonylurea treatment and increased birthweight and/or neonatal hypoglycaemia. We show that both of these novel mutations and -192C>G impair the function of the promoter in transient transfection assays.
Two novel mutations identified here and the previously identified late-onset diabetes mutation, -192C>G, impair the function of the HNF4A P2 promoter in vitro.

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Available from: Lorna W Harries, Sep 03, 2014
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    • "In conclusion, our experiments show that HNF4A is not only regulated on the transcriptional level via its P1 [79] and P2 [20] promoters and the enhancer [79], but also on the posttranscriptional level via several distinct elements in the two 3′UTRs (Fig. 9). "
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    • "Clearly, partial mutation (three of twelve base pairs) of the HNF1 site of the promoter (Figure 6C) abolished HNF1B regulation completely. HNF1B transactivation via the HNF1 binding site in the lhx1 promoter is about 70% (Figure 6A) compared to the effect seen with the HNF4A P2 promoter, a well studied HNF1B target [46,47]. "
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    • "The transcription start site at position −23 is indicated by an asterisk. Figure 4. Mutations and predicted nuclear factor binding sites within the HNF4A P2 promoter using Transcription Element Search System and according to Wirsing et al. (2010). Nucleotides are numbered according to the A of the ATG codon (bold). "
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