Evidence of interaction between PPARG2 and HNF4A contributing to variation in insulin sensitivity in Mexican Americans

Diabetes. 2008 Apr;57(4):1048-56. doi: 10.2337/db07-0848. Epub 2007 Dec 27.

Abstract

Objective: We hypothesized that interaction between PPARG2 Pro12Ala and variants in the promoter region of HNF4A are associated with type 2 diabetes-related quantitative traits in Mexican-American families of a proband with previous gestational diabetes.

Research design and methods: The BetaGene project genotyped PPARG2 Pro12Ala and nine HNF4A single nucleotide polymorphisms (SNPs) in 473 individuals in 89 families. Members of the proband generation had fasting glucose <126 mg/dl and were phenotyped by oral and intravenous glucose tolerance tests.

Results: Neither PPARG2 Pro12Ala nor any of the nine HNF4A SNPs were independently associated with type 2 diabetes-related quantitative traits. However, the interaction between PPARG2 Pro12Ala and HNF4A rs2144908 was significantly associated with both insulin sensitivity (S(I)) (Bonferroni P = 0.0006) and 2-h insulin (Bonferroni P = 0.039). Subjects with at least one PPARG2 Ala allele and homozygous for the HNF4A rs2144908 A allele had 40% higher S(I) compared with individuals with at least one G allele. S(I) did not vary by rs2144908 genotype among PPARG2 Pro/Pro. The interaction result for S(I) was replicated by the Insulin Resistance Atherosclerosis Family Study (P = 0.018) in their San Antonio sample (n = 484) where subjects with at least one PPARG2 Ala allele and homozygous for the HNF4A rs2144908 A allele had a 29% higher S(I) compared with individuals with at least one G allele. However, the interaction was not replicated in their San Luis Valley sample (n = 496; P = 0.401).

Conclusions: Together, these results suggest that variation in PPARG2 and HNF4A may interact to regulate insulin sensitivity in Mexican Americans at risk for type 2 diabetes.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Substitution
  • Diabetes Mellitus, Type 2 / genetics*
  • Diabetes, Gestational / genetics*
  • Female
  • Genetic Variation*
  • Hepatocyte Nuclear Factor 4 / metabolism*
  • Hispanic Americans / genetics*
  • Humans
  • Insulin / physiology*
  • Male
  • PPAR gamma / metabolism*
  • Phenotype
  • Polymorphism, Single Nucleotide
  • Pregnancy
  • Promoter Regions, Genetic*
  • Risk Factors
  • San Francisco
  • Siblings
  • Texas

Substances

  • HNF4A protein, human
  • Hepatocyte Nuclear Factor 4
  • Insulin
  • PPAR gamma