Assessment of DNA methylation at the interferon regulatory factor 5 (IRF5) promoter region in inflammatory bowel diseases

  • Alfred Balasa
  • Grace Gathungu
  • Peter Kisfali
  • E O’Brian Smith
  • Judy H. Cho
  • Bela Melegh
  • Richard Kellermayer
Original Article

Abstract

Background and aims

A 5-bp insertion–deletion (indel) polymorphism in the promoter of interferon regulatory factor 5 (IRF5) has been associated with inflammatory bowel diseases (IBD). This polymorphism generates an additional binding site for the transcription factor SP1 and has been shown to augment the expression of IRF5. Additionally, it affects a CpG dinucleotide-dense genomic region. These features of the indel suggested that it may influence the epigenetic regulation of IRF5. The aim of this study was to investigate the potential effect of the 5-bp indel on the methylation pattern of four CpG sites upstream of the polymorphism. Possible CpG site methylation differences in this region between healthy persons and individuals suffering from IBD were also tested.

Methods

Genotype was determined by 4% polyacrylamide gel electrophoresis in 33 peripheral blood leukocyte (PBL) DNA samples. DNA methylation correlates of the genotypes were measured by bisulfite pyrosequencing. IRF5 promoter methylation in association to disease state was assessed in 87 proband (49 healthy, 18 Crohn’s disease, 20 ulcerative colitis) PBL samples.

Results

The polymorphism did not affect the methylation pattern of the IRF5 promoter nor could we detect significant differences in the average, low methylation of the locus between healthy persons and individuals with IBD.

Conclusions

These results implicate that epigenetic dysregulation of the IRF5 promoter is unlikely to be associated with IBD.

Keywords

IRF5 DNA methylation Inflammatory bowel diseases Polymorphism 

Notes

Acknowledgments

R.K. was supported by funding from the Broad Medical Research Program, the Broad Foundation (IBD-0252), and a young investigator joint award from the Crohn’s and Colitis Foundation of America—Children’s Digestive Health and Nutrition Foundation/North American Society of Pediatric Gastroenterology Hepatology and Nutrition (CCFA Ref #2426).

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Copyright information

© Springer-Verlag 2010

Authors and Affiliations

  • Alfred Balasa
    • 1
  • Grace Gathungu
    • 2
  • Peter Kisfali
    • 3
  • E O’Brian Smith
    • 4
  • Judy H. Cho
    • 2
  • Bela Melegh
    • 3
  • Richard Kellermayer
    • 1
    • 5
  1. 1.Section of Pediatric GastroenterologyBaylor College of MedicineHoustonUSA
  2. 2.Section of Digestive Disease, Department of Internal MedicineYale UniversityNew HavenUSA
  3. 3.Department of Medical GeneticsUniversity of PecsPecsHungary
  4. 4.USDA Children’s Nutrition Research CenterHoustonUSA
  5. 5.Section of Pediatric Gastroenterology, Hepatology & NutritionBaylor College of MedicineHoustonUSA

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