Polymorphisms of the UCP2 Gene Are Associated with Glomerular Filtration Rate in Type 2 Diabetic Patients and with Decreased UCP2 Gene Expression in Human Kidney

PLoS One. 2015 Jul 28;10(7):e0132938. doi: 10.1371/journal.pone.0132938. eCollection 2015.

Abstract

Introduction: Uncoupling protein 2 (UCP2) reduces production of reactive oxygen species (ROS) by mitochondria. ROS overproduction is one of the major contributors to the pathogenesis of chronic diabetic complications, such as diabetic kidney disease (DKD). Thus, deleterious polymorphisms in the UCP2 gene are candidate risk factors for DKD. In this study, we investigated whether UCP2 -866G/A, Ala55Val and Ins/Del polymorphisms were associated with DKD in patients with type 2 diabetes mellitus (T2DM), and whether they had an effect on UCP2 gene expression in human kidney tissue biopsies.

Materials and methods: In a case-control study, frequencies of the UCP2 -866G/A, Ala55Val and Ins/Del polymorphisms as well as frequencies of the haplotypes constituted by them were analyzed in 287 T2DM patients with DKD and 281 T2DM patients without this complication. In a cross-sectional study, UCP2 gene expression was evaluated in 42 kidney biopsy samples stratified according to the presence of the UCP2 mutated -866A/55Val/Ins haplotype.

Results: In the T2DM group, multivariate logistic regression analysis showed that the -866A/55Val/Ins haplotype was an independent risk factor for DKD (OR = 2.136, 95% CI 1.036-4.404), although neither genotype nor allele frequencies of the individual polymorphisms differed between case and control groups. Interestingly, T2DM patients carrying the mutated haplotype showed decreased estimated glomerular filtration rate (eGFR) when compared to subjects with the reference haplotype (adjusted P= 0.035). In kidney biopsy samples, UCP2 expression was significantly decreased in UCP2 mutated haplotype carriers when compared to kidneys from patients with the reference haplotype (0.32 ± 1.20 vs. 1.85 ± 1.16 n fold change; adjusted P< 0.000001).

Discussion: Data reported here suggest that the UCP2 -866A/55Val/Ins haplotype is associated with an increased risk for DKD and with a lower eGFR in T2DM patients. Furthermore, this mutated haplotype was associated with decreased UCP2 gene expression in human kidneys.

Publication types

  • Clinical Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Amino Acid Substitution
  • Diabetes Mellitus, Type 2* / genetics
  • Diabetes Mellitus, Type 2* / metabolism
  • Diabetes Mellitus, Type 2* / pathology
  • Diabetic Nephropathies* / genetics
  • Diabetic Nephropathies* / metabolism
  • Diabetic Nephropathies* / pathology
  • Female
  • Gene Expression Regulation*
  • Glomerular Filtration Rate / genetics*
  • Humans
  • Ion Channels* / biosynthesis
  • Ion Channels* / genetics
  • Kidney / metabolism*
  • Kidney / pathology
  • Male
  • Mitochondrial Proteins* / biosynthesis
  • Mitochondrial Proteins* / genetics
  • Mutation, Missense*
  • Uncoupling Protein 2

Substances

  • Ion Channels
  • Mitochondrial Proteins
  • UCP2 protein, human
  • Uncoupling Protein 2

Grants and funding

This study was partially supported by grants from Fundação de Amparo à Pesquisa do Estado do Rio Grande do Sul (FAPERGS), Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Coordenação de Aperfeiçoamento de Pessoa de Nível Superior (CAPES) and Fundo de Incentivo à Pesquisa e Eventos (FIPE) at Hospital de Clínicas de Porto Alegre. D Crispim and LH Canani are recipients of scholarships from CNPq.