Differential methylation of TCF7L2 promoter in peripheral blood DNA in newly diagnosed, drug-naïve patients with type 2 diabetes

PLoS One. 2014 Jun 10;9(6):e99310. doi: 10.1371/journal.pone.0099310. eCollection 2014.

Abstract

TCF7L2 is the susceptibility gene for Type 2 diabetes (T2D) with the largest effect on disease risk that has been discovered to date. However, the mechanisms by which TCF7L2 contributes to the disease remain largely elusive. In addition, epigenetic mechanisms, such as changes in DNA methylation patterns, might have a role in the pathophysiology of T2D. This study aimed to investigate the differences in terms of DNA methylation profile of TCF7L2 promoter gene between type 2 diabetic patients and age- and Body Mass Index (BMI)- matched controls. We included 93 type 2 diabetic patients that were recently diagnosed for T2D and exclusively on diet (without any pharmacological treatment). DNA was extracted from whole blood and DNA methylation was assessed using the Sequenom EpiTYPER system. Type 2 diabetic patients were more insulin resistant than their matched controls (mean HOMA IR 2.6 vs 1.8 in controls, P<0.001) and had a poorer beta-cell function (mean HOMA B 75.7 vs. 113.6 in controls, P<0.001). Results showed that 59% of the CpGs analyzed in TCF7L2 promoter had significant differences between type 2 diabetic patients and matched controls. In addition, fasting glucose, HOMA-B, HOMA-IR, total cholesterol and LDL-cholesterol correlated with methylation in specific CpG sites of TCF7L2 promoter. After adjustment by age, BMI, gender, physical inactivity, waist circumference, smoking status and diabetes status uniquely fasting glucose, total cholesterol and LDL-cholesterol remained significant. Taken together, newly diagnosed, drug-naïve type 2 diabetic patients display specific epigenetic changes at the TCF7L2 promoter as compared to age- and BMI-matched controls. Methylation in TCF7L2 promoter is further correlated with fasting glucose in peripheral blood DNA, which sheds new light on the role of epigenetic regulation of TCF7L2 in T2D.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Case-Control Studies
  • CpG Islands / genetics
  • DNA / blood*
  • DNA Methylation / genetics*
  • Diabetes Mellitus, Type 2 / blood*
  • Diabetes Mellitus, Type 2 / diagnosis
  • Diabetes Mellitus, Type 2 / genetics*
  • Diabetes Mellitus, Type 2 / metabolism
  • Female
  • Humans
  • Male
  • Metabolomics
  • Promoter Regions, Genetic*
  • Transcription Factor 7-Like 2 Protein / genetics*

Substances

  • TCF7L2 protein, human
  • Transcription Factor 7-Like 2 Protein
  • DNA

Grants and funding

This work was supported by the FIS Grant PI 1000219, the MEDIGENE project, grant agreement number 279171, funded by the EC Seventh Framework Programme theme FP7-HEALTH-2011 and by the Spanish Ministry of Science and Innovation (under the grant agreement number SAF 2010-19527). CIBER de Diabetes y Enfermedades Metabólicas is an initiative of ISCIII (Spanish Ministry of Science and Innovation). Dr. Canivell was awarded with the Rio Hortega Grant from the Spanish Ministry of Science and Innovation. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.