Lack of association between uncoupling protein-2 Ala55Val polymorphism and incident diabetes in the atherosclerosis risk in communities study

Role of Uncoupling Protein 2 Gene Polymorphisms on the Risk of Ischemic Stroke in a Sardinian Population

The mitochondrial uncoupling protein 2 (UCP2) acts as an anion transporter and as an antioxidant factor able to reduce the reactive oxygen species level. Based on its effects, UCP2 prevents the membrane lipids, proteins, and DNA damage while preserving normal cellular functions. Many variants have been identified within the human UCP2. Some of them were associated with a higher risk of obesity, diabetes and cardiovascular diseases in different populations. UCP2 appears a suitable candidate also for the risk of ischemic stroke. In the current study, we investigated the possible association between few variants of UCP2 (rs659366, rs660339, rs1554995310) and the risk of ischemic stroke in a genetically homogenous cohort of cases and controls selected in Sardinia Island. This population has been previously analysed for other candidate genes. A total of 250 cases of ischemic stroke and 241 controls were enrolled in the study. The allelic/genotypic distribution of the 3 UCP2 variants was characterized and compared among cases and controls. The results of our study confirmed known risk factors for ischemic stroke: age, history of smoking, hypertension, hypercholesterolemia, and atrial fibrillation. No association was found between the 3 UCP2 variants and the risk of ischemic stroke in our Sardinian cohort.

Association of uncoupling protein-2 -866G/A and Ala55Val polymorphisms with susceptibility to type 2 diabetes mellitus: A meta-analysis of case-control studies

BACKGROUND

Recently, the relationships between uncoupling protein-2 (UCP2) -866G/A (rs659366) and Ala55Val (rs660339) polymorphisms and the risk of type 2 diabetes mellitus (T2DM) have been explored considerably, but the results are greatly inconsistent. This meta-analysis was performed to further identify the association of UCP2 rs659366 and rs660339 with the risk of T2DM.

METHODS

Eligible studies were searched from PubMed, Embase, Cochrane Library, VIP database, Chinese National Knowledge Infrastructure, and Chinese WanFang database until March 8, 2020. The odds ratios with corresponding 95% confidence intervals (CIs), and P-values were used to assess the strength of the association.

RESULTS

A total of 26 studies were included in this study. UCP2 rs659366 was associated with the risk of T2DM in allele model (OR: 1.112, 95%CI: 1.009-1.224, P = 0.032), dominant model (OR: 1.189, 95%CI: 1.035-1.366, P = 0.014), and heterozygous model (OR: 1.177, 95%CI: 1.032-1.342, P = .015). A significantly increased risk of T2DM was detected in Asians by UCP2 rs659366 allele (OR: 1.132, 95%CI: 1.016-1.262, P = .025), dominant (OR: 1.218, 95%CI: 1.046-1.418, P = .011), homozygous (OR: 1.254, 95%CI: 1.022-1.540, P = .031) or heterozygous (OR: 1.198, 95%CI: 1.047-1.371, P = .009) models. There was no significant correlation between UCP2 rs660339 and the risk of T2DM (P>.05).

CONCLUSIONS

The UCP2 rs65366 is significantly associated with the risk of T2DM, especially in Asian population, while no evidence is found between the UCP2 rs660339 and the susceptibility to T2DM.

Association and in silico studies of ENPP1 gene variants with type 2 diabetes mellitus in a Northern Iranian population

In the current study, a sample population of Northern Iranians was selected to investigate the association of K121Q, rs1799774, rs7754561, and rs997509 ENPP1 gene variants and their haplotypes with T2DM. Genomic DNAs of 978 samples were extracted by Salting Out standard technique and then genotyped by the TaqMan assay. The results show significant differences between study groups for K121Q (p = 0.0004) under a Dominant and rs7754561 (p = 0.002) under a co-dominant hereditary model. Based on allele frequency, there was a significant difference between two study groups at K121Q and rs7754561 variants (p = 0.010 and p = 0.01, respectively). There was no evidence for an association between ENPP1 haplotypes and overall risk of T2DM. Genotype-phenotype sub-analyses showed no significant relationship of four studied polymorphisms with age, gender, FBS, and systolic and diastolic blood pressures. Homology modeling and molecular docking of ENPP1 in K173 and Q173 models with ATP, AMP, and 2'3'-cGAMP as ligands revealed that all ligands had a more binding affinity to Lys173 protein model, and 2'3'-cGAMP had a higher affinity to both ENPP1 protein models compared to ATP and AMP. These findings suggest that ENPP1 gene variants may have a potential impact on the occurrence of T2DM in Northern Iranians.

UCP2 and UCP3 variants and gene-environment interaction associated with prediabetes and T2DM in a rural population: a case control study in China

Background

There are disparities for the association between uncoupling proteins (UCP) and type 2 diabetes (T2DM). The study was to examine the associations of genetic variants of UCP2 and UCP3 with prediabetes and T2DM in a rural Chinese population.

Methods

A population-based case-control study of 397 adults with T2DM, 394 with prediabetes and 409 with normal glucose tolerance (NGT) was carried out in 2014 in a rural community in eastern China. Three groups were identified through a community survey and the prediabetes and NGT groups were frequently matched by age and gender with the T2DM group and they were not relatives of T2DM subjects. With r² ≥ 0.8 and minor allele frequency (MAF) ≥0.05 for tag single nucleotide polymorphisms (SNPs) with potential function, three (rs660339, rs45560234 and rs643064) and six (rs7930460, rs15763, rs647126, rs1800849, rs3781907 and rs1685356) SNPs were selected respectively for UCP2 and UCP3 and genotyped in real time using the MassARRAY system (Sequenom; USA). The haplotypes, gene-environmental interaction and association between genetic variants of UCP2 and UCP3 and prediabetes or T2DM were explored.

Results

There were no significant differences in age and sex among three study groups. After the adjustment for possible covariates, the A allele of rs1800849 in UCP3 was significantly associated with prediabetes (aOR_{AA vs GG} = 1.68, 95% CI: 1.02–2.78), and the association was also significant under the recessive model (aOR _{AA vs GA + GG} = 1.64, 95% CI: 1.02–2.66). Also, rs15763 was found to be marginally significantly associated with T2DM under dominant model (OR_{GA + AA vs GG} = 0.73, 95% CI: 0.52–1.03, P = 0.072). No haplotype was significantly associated with prediabetes or T2DM. Multiplicative interactions for rs660339-overweight on T2DM were observed. In addition, the AA genotype of rs660339 was associated with an increased risk of T2DM in overweight subjects (OR = 1.48, 95%CI: 0.87–2.52) but with a decreased risk in those with normal weight (OR = 0.54, 95%CI: 0.28–1.05).

Conclusions

Rs1800849 in UCP3 was significantly associated with prediabetes. Overweight might modify the effects of rs660339 of UCP2 on T2DM.

Electronic supplementary material

The online version of this article (10.1186/s12881-018-0554-4) contains supplementary material, which is available to authorized users.

Meta-analysis reveals the association of common variants in the uncoupling protein (UCP) 1-3 genes with body mass index variability

Background

The relationship between uncoupling protein (UCP) 1–3 polymorphisms and susceptibility to obesity has been investigated in several genetic studies. However, the impact of these polymorphisms on obesity is still under debate, with contradictory results being reported. Until this date, no meta-analysis evaluated the association of UCP polymorphisms with body mass index (BMI) variability. Thus, this paper describe a meta-analysis conducted to evaluate if the -3826A/G (UCP1); -866G/A, Ala55Val and Ins/Del (UCP2) and -55C/T (UCP3) polymorphisms are associated with BMI changes.

Methods

A literature search was run to identify all studies that investigated associations between UCP1-3 polymorphisms and BMI. Weighted mean differences (WMD) were calculated for different inheritance models.

Results

Fifty-six studies were eligible for inclusion in the meta-analysis. Meta-analysis results showed that UCP2 55Val/Val genotype was associated with increased BMI in Europeans [Random Effect Model (REM) WMD 0.81, 95% CI 0.20, 1.41]. Moreover, the UCP2 Ins allele and UCP3-55T/T genotype were associated with increased BMI in Asians [REM WMD 0.46, 95% CI 0.09, 0.83 and Fixed Effect Model (FEM) WMD 1.63, 95% CI 0.25, 3.01]. However, a decreased BMI mean was observed for the UCP2-866 A allele in Europeans under a dominant model of inheritance (REM WMD −0.18, 95% CI −0.35, −0.01). There was no significant association of the UCP1-3826A/G polymorphism with BMI mean differences.

Conclusions

The meta-analysis detected a significant association between the UCP2-866G/A, Ins/Del, Ala55Val and UCP3-55C/T polymorphisms and BMI mean differences.

The ENPP1 K121Q polymorphism is not associated with type 2 diabetes in northern Chinese

The K121Q polymorphism of the ectoenzyme nucleotide pyrophosphate phosphodiesterase 1 (ENPP1) gene has been studied in relation to insulin resistance, type 2 diabetes, and obesity, and conflicting results were observed in various populations. The purpose of the present study was to investigate the prevalence of K121Q polymorphism of ENPP1 gene and to clarify whether this polymorphism is associated with type 2 diabetes susceptibility in northern Chinese population. We studied the association of the ENPP1 K121Q polymorphism with type 2 diabetes (T2D) in 639 unrelated patients and 885 control subjects with normal glucose tolerance of northern China. The patients were diagnosed in accordance with the guidelines of the American Diabetes Association (ADA). Genotypes were determined by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. The distribution of KK, KQ, and QQ genotypes among patients was 79.5, 19.2, and 1.3%, similar to that of the control group (79.2, 20.1, and 0.7%). After readjusting for the confounding effects of age, gender, and BMI, no significant effect of genotypes on T2D was found for any of the genetic models tested (recessive model, dominant model, or additive model). All clinical characteristics tested were similar among the different genotypes, and no significant associations were observed both in T2D patients and in controls. When subgroup analyses of T2D patients and non-diabetic controls were stratified according to BMI and waist circumference, the variant was still not associated with T2D. The results showed that the ENPP1 K121Q polymorphism is not associated with genetic susceptibility of type 2 diabetes in the northern Chinese population.

Uncoupling protein 2 Ala55Val polymorphism is associated with a higher acute insulin response to glucose

Recent evidence suggests that mitochondrial uncoupling protein 2 (UCP2) in pancreatic beta-cells plays a crucial role in insulin production and secretion. We hypothesized that 2 UCP2 polymorphisms, a -55C/T (Ala55Val) substitution in exon 4 and an exon 8 insertion, would alter the acute insulin response to glucose (AIRg). Subjects were 155 African American (AA) and European American (EA) women. Body composition was determined by dual-energy x-ray absorptiometry. Insulin sensitivity and AIRg were measured with an intravenous glucose tolerance test and minimal modeling. To account for the confounding effects of population stratification, estimates of African admixture were obtained from approximately 35 ancestry-informative markers. Uncoupling protein 2 genotyping was conducted with gel electrophoresis. Information was analyzed using mixed linear models. A positive association between the -55C/T homozygous mutation and AIRg was identified in the total sample (P < .01) and independently in EA women (P = .02) but not AA women. The exon 8 insertion did not significantly affect AIRg. No interaction effects of the 2 polymorphisms on AIRg were noted. These results indicate that AIRg is associated with the -55C/T UCP2 homozygous mutation and that the presence of this mutation could alter postchallenge insulin concentration.