A/G heterozygote of the A-3826G polymorphism in the UCP-1 gene has higher BMI than A/A and G/G homozygote in young Japanese males

Genetics of Obesity in East Asians

Obesity has become a public health problem worldwide. Compared with Europe, people in Asia tend to suffer from type 2 diabetes with a lower body mass index (BMI). Genome-wide association studies (GWASs) have identified over 750 loci associated with obesity. Although the majority of GWAS results were conducted in individuals of European ancestry, a recent GWAS in individuals of Asian ancestry has made a significant contribution to the identification of obesity susceptibility loci. Indeed, owing to the multifactorial character of obesity with a strong environmental component, the revealed loci may have distinct contributions in different ancestral genetic backgrounds and in different environments as presented through diet and exercise among other factors. Uncovering novel, yet unrevealed genes in non-European ancestries may further contribute to explaining the missing heritability for BMI. In this review, we aimed to summarize recent advances in obesity genetics in individuals of Asian ancestry. We therefore compared proposed mechanisms underlying susceptibility loci for obesity associated with individuals of European and Asian ancestries and discussed whether known genetic variants might explain ethnic differences in obesity risk. We further acknowledged that GWAS implemented in individuals of Asian ancestries have not only validated the potential role of previously specified obesity susceptibility loci but also exposed novel ones, which have been missed in the initial genetic studies in individuals of European ancestries. Thus, multi-ethnic studies have a great potential not only to contribute to a better understanding of the complex etiology of human obesity but also potentially of ethnic differences in the prevalence of obesity, which may ultimately pave new avenues in more targeted and personalized obesity treatments.

Association of uncoupling protein (Ucp) gene polymorphisms with cardiometabolic diseases

The hereditary aspect of obesity is a major focus of modern medical genetics. The genetic background is known to determine a higher-than-average prevalence of obesity in certain regions, like Oceania. There is evidence that dysfunction of brown adipose tissue (BAT) may be a risk factor for obesity and type 2 diabetes (T2D). A significant number of studies in the field focus on the UCP family. The Ucp genes code for electron transport carriers. UCP1 (thermogenin) is the most abundant protein of the UCP superfamily and is expressed in BAT, contributing to its capability of generating heat. Single nucleotide polymorphisms (SNPs) of Ucp1-Ucp3 were recently associated with risk of cardiometabolic diseases. This review covers the main Ucp SNPs A-3826G, A-1766G, A-112C, Met229Leu, Ala64Thr (Ucp1), Ala55Val, G-866A (Ucp2), and C-55 T (Ucp3), which may be associated with the development of obesity, disturbance in lipid metabolism, T2D, and cardiovascular diseases.

Role of the Polymorphisms of Uncoupling Protein Genes in Childhood Obesity and Their Association with Obesity-Related Disturbances

BACKGROUND

Obesity, one of the most common disorders observed in clinical practice, has been associated with energy metabolism-related protein genes such as uncoupling proteins (UCPs). Herein, we evaluated UCPs as candidate genes for obesity and its morbidities.

METHODS

A total of 268 obese and 185 nonobese children and adolescents were enrolled in this study. To determine dyslipidemia, hypertension, and insulin resistance, laboratory tests were derived from fasting blood samples. UCP1-3826 A/G, UCP2 exon 8 deletion/insertion (del/ins), and UCP3-55C/T variants were also genotyped, and the relationships among the polymorphisms of these UCPs and obesity morbidities were investigated.

RESULTS

The mean ages of the obese and control groups were 11.61 ± 2.83 and 10.74 ± 3.36 years, respectively. The respective genotypic frequencies of the AA, AG, and GG genotypes of UCP1 were 46.3%, 33.2%, and 20.5% in obese subjects and 46.5%, 42.2%, and 11.4% in the controls (p = 0.020). G alleles were more frequent in obese subjects with hypertriglyceridemia (42.9%; p = 0.048) than in those without, and the GG genotype presented an odds ratio for obesity of 2.02 (1.17-3.47; p = 0.010). The polymorphisms of UCP2 exon 8 del/ins and UCP3-55C/T did not influence obesity risk (p > 0.05). The I (ins) allele was associated with low HDL cholesterolemia (p = 0.023).

CONCLUSION

The GG genotype of the UCP1-3826 A/G polymorphism appears to contribute to the onset of childhood obesity in Turkish children. The GG genotype of UCP1, together with the del/del genotype of the UCP2 polymorphism, may increase the risk of obesity with synergistic effects. The ins allele of the UCP2 exon 8 del/ins polymorphism may contribute to low HDL cholesterolemia.

Role of UCP1 Gene Variants in Interethnic Differences in the Development of Cardio-Metabolic Diseases

Cardio-metabolic diseases (CMDs) comprise a cluster of risk factors that contribute to chronic pathological conditions with adverse consequences for cardiovascular function and metabolic processes. A wide range of CMD prevalence rates among different ethnic groups has been documented. In view of accumulated evidence, there is a trend toward increasing CMD prevalence rates in Eastern Europe and Western Asia. Numerous studies have revealed an association between uncoupling protein 1 (UCP1) gene variants and CMDs. UCP1 activity is essential for brown adipose tissue (BAT)-mediated thermogenesis. Experimental animal studies and epidemiological studies in humans highlight the significance of BAT-mediated thermogenesis in protecting against obesity and maintaining a lean phenotype. We hypothesize that the genetic variation in UCP1 gene expression observed among different ethnic groups could contribute to the ethnic-specific predisposition to CMD development. Constructing such prevalence maps of UCP1 gene variants could contribute significantly into identifying high-risk ethnic groups predisposed to the development of CMDs, and further shaping public health policies by the improvement of existing preventive and management strategies.

Effect of the beta-3 adrenergic receptor Trp64Arg and uncoupling protein 1-3826 A>G genotypes on lipid and apolipoprotein levels in overweight/obese and non-obese Chinese subjects

BACKGROUND

The beta-3 adrenergic receptor (β3-AR) Trp64Arg and uncoupling protein 1 (UCP1) -3826 A>G polymorphisms have been reported to be associated with obesity and/or lipid metabolism in some populations. This study examined the possible association of the β3-AR and UCP1 polymorphisms with overweight/obesity or lipid variation in a Southwest Chinese population.

METHODS

A total of 418 Han Chinese (249 overweight/obese and 169 healthy control subjects) in the Chengdu area were studied using PCR-RFLP analysis. Total serum cholesterol (TC) and triglycerides (TGs) were measured using an enzymatic method. High density lipoprotein cholesterol (HDL-C) was determined after sodium phosphotungstate/magnesium chloride precipitation of low-density lipoproteins by polyvinyl sulfate. Serum apolipoproteins were quantified by radial immunodiffusion.

RESULTS

The genotype and allele frequencies of the β3-AR Trp64Arg and UCP1 -3826 A>G polymorphisms in overweight/obese subjects exhibited no significant differences compared to the controls. However, subjects carrying the β3-AR TrpTrp genotype and UCP1 AG genotype had higher TG levels than those carrying the Arg allele and AA genotype, respectively (P<0.05), while controls carrying the β3-AR Arg allele had significantly higher TC and apo AII concentrations than those carrying the TrpTrp genotype (P<0.05). Additionally, subjects carrying the UCP1 AG genotype exhibited elevated apo C-II and apo C-III levels compared to those carrying the AA genotype (P<0.05). We were unable to find an association of the UCP1 and β3-AR polymorphisms with low HDL-cholesterolemia in the overweight/obese subjects.

CONCLUSIONS

The present study provides evidence that the β3-AR Trp64Arg and UCP1 -3826 A>G polymorphisms are associated with TG levels in overweight/obese Chinese subjects and that the two polymorphisms are also associated with certain lipid and apolipoprotein variations, depending on BMI. However, these polymorphisms are not associated with overweight/obesity or low HDL-cholesterolemia in a Chinese population from the Chengdu area.

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 presence of at least three alleles of the ADRB3 Trp64Arg (C/T) and UCP1 -3826A/G polymorphisms is associated with protection to overweight/obesity and with higher high-density lipoprotein cholesterol levels in Caucasian-Brazilian patients with type 2 diabetes

BACKGROUND

We investigated whether the -3826A/G polymorphism (rs1800592) of the uncoupling protein 1 gene (UCP1) and the Trp64Arg polymorphism (rs4994) of the β3-adrenergic receptor gene (ADRB3) are associated with type 2 diabetes mellitus (T2DM) and features of metabolic syndrome in a Brazilian-Caucasian population.

METHODS

Both polymorphisms were genotyped in 1015 T2DM patients and 561 nondiabetic subjects. The combined effect of both polymorphisms on T2DM and metabolic syndrome-related parameters was analyzed according to a triallelic inheritance pattern, by which at least three minor alleles from two loci are necessary for trait manifestation.

RESULTS

UCP1 -3826A/G and ADRB3 Trp64Arg polymorphisms were not associated with T2DM (P>0.05). Patients carrying the ADRB3 64Arg allele had higher fasting plasma glucose and high-density lipoprotein cholesterol (HDL-C) than patients with the Trp64Trp genotype (P=0.0001 and P=0.015, respectively). The 64Arg allele was also associated with protection against overweight/obesity (body mass index ≥ 25 kg/m(2); odds ratio [OR]=0.598; P=0.014). Interestingly, prevalence of overweight/obesity was lower among carriers of at least three minor alleles of the -3826A/G and ADRB3 Trp64Arg polymorphisms than among patients with fewer than three minor alleles (54.5% vs. 79.1%; OR=0.288; P=0.007, respectively). Subjects with at least three minor alleles also had higher HDL-C levels (P=0.018).

CONCLUSIONS

UCP1 -3826A/G and ADRB3 Trp64Arg polymorphisms may have a combined effect in the modulation of overweight/obesity and HDL-C levels in type 2 diabetes mellitus (T2DM) Caucasian-Brazilian patients.

The role of the uncoupling protein 1 (UCP1) on the development of obesity and type 2 diabetes mellitus

It is well established that genetic factors play an important role in the development of both type 2 diabetes mellitus (DM2) and obesity, and that genetically susceptible subjects can develop these metabolic diseases after being exposed to environmental risk factors. Therefore, great efforts have been made to identify genes associated with DM2 and/or obesity. Uncoupling protein 1 (UCP1) is mainly expressed in brown adipose tissue, and acts in thermogenesis, regulation of energy expenditure, and protection against oxidative stress. All these mechanisms are associated with the pathogenesis of DM2 and obesity. Hence, UCP1 is a candidate gene for the development of these disorders. Indeed, several studies have reported that polymorphisms -3826A/G, -1766A/G and -112A/C in the promoter region, Ala64Thr in exon 2 and Met299Leu in exon 5 of UCP1 gene are possibly associated with obesity and/or DM2. However, results are still controversial in different populations. Thus, the aim of this study was to review the role of UCP1 in the development of these metabolic diseases.

UCP2 I/D modulated change in BMI during a lifestyle modification intervention study in Japanese subjects

AIM

Polymorphisms in uncoupling protein (UCP) genes have been strongly associated with energy expenditure and obesity. This study aimed at investigating the effects of UCP gene polymorphisms (UCP1 -3826A/G, UCP2A/V, UCP2 I/D, and UCP3 -55C/T) on change in body mass index (BMI) during a lifestyle modification program in Japanese subjects.

RESULTS

Intervention induced a significant decrease in energy intake (-8.6% ± 17.0%) and a significant increase in energy expenditure (7.7% ± 7.4%). As a result, participants experienced a significant decrease in their BMI of -1.8% ± 2.7%. In a multivariate regression analysis, only UCP2 D/I among the selected UCP gene polymorphisms was associated with a change in BMI independent of the effects of gender, age, baseline BMI, changes in energy intake, and expenditure. Further regression analysis revealed that, in contrast to the DD genotype group, the DI+II genotype group showed no significant association between weight loss and change in energy expenditure suggesting this polymorphism altered the effects of this parameter on change in BMI.

CONCLUSION

The study found UCP2 D/I to be associated with change in BMI by altering the effect of change in energy expenditure on change in BMI.

The Association Between the Uncoupling Protein-1 Gene A-3826G Polymorphism and High-density Lipoprotein Cholesterol in A General Japanese Population: A Consideration of the Obesity Status

BACKGROUND

Limited studies have shown inconsistent data about the association between the uncoupling protein 1 (UCP1) gene A-3826G polymorphism and high-density lipoprotein (HDL) cholesterol levels. The present study investigated the association between the A-3826G polymorphism and low HDL-cholesterolemia in non-obese and obese subjects.

METHODS

Anthropometric and biochemical factors, in addition to genotyping by an allele-specific DNA assay, were measured in 294 community-dwelling Japanese subjects (male/female: 127/167, mean age: 65 years). Obesity was defined as a body mass index (BMI) ≥ 25 kg/m(2), and low HDL-cholesterolemia was defined as < 1.04 mmol/L of HDL-cholesterol.

RESULTS

The subjects with the G/G genotype (n = 27) showed a significantly higher prevalence of low HDL-cholesterolemia (37%) than those with the A/A + A/G genotype (13%) in the obese group (n = 102). There was a non-significant difference in the prevalence of low HDL-cholesterolemia between subjects with the G/G genotype (n = 45, 13%) and with the A/A + A/G genotype (15%) in the non-obese group (n = 192). A multivariate-adjusted logistic regression analysis of the presence of low HDL-cholesterolemia revealed that carrying the G/G genotype was an independent and significant factor positively associated with low HDL-cholesterolemia [odds ratio (OR): 6.85, 95% confidence interval (CI): 1.65-28.49] in the obese group, while carrying the G/G genotype exhibited a non-significant but reduced OR, by one-half, for low HDL-cholesterolemia (OR: 0.51, 95% CI: 0.13-1.96) in the non-obese group.

CONCLUSIONS

The obesity status could have opposing impacts on the relationship between the G/G genotype and low HDL-cholesterolemia, providing insight into the need to consider the obesity levels when studying the association between the UCP-1 gene A-3826G polymorphism and HDL-cholesterol.

KEYWORDS

Obesity; Body mass index; HDL-C; Atherosclerotic risk.

Mitochondrial-nuclear epistasis: implications for human aging and longevity

There is substantial evidence that mitochondria are involved in the aging process. Mitochondrial function requires the coordinated expression of hundreds of nuclear genes and a few dozen mitochondrial genes, many of which have been associated with either extended or shortened life span. Impaired mitochondrial function resulting from mtDNA and nuclear DNA variation is likely to contribute to an imbalance in cellular energy homeostasis, increased vulnerability to oxidative stress, and an increased rate of cellular senescence and aging. The complex genetic architecture of mitochondria suggests that there may be an equally complex set of gene interactions (epistases) involving genetic variation in the nuclear and mitochondrial genomes. Results from Drosophila suggest that the effects of mtDNA haplotypes on longevity vary among different nuclear allelic backgrounds, which could account for the inconsistent associations that have been observed between mitochondrial DNA (mtDNA) haplogroups and survival in humans. A diversity of pathways may influence the way mitochondria and nuclear-mitochondrial interactions modulate longevity, including: oxidative phosphorylation; mitochondrial uncoupling; antioxidant defenses; mitochondrial fission and fusion; and sirtuin regulation of mitochondrial genes. We hypothesize that aging and longevity, as complex traits having a significant genetic component, are likely to be controlled by nuclear gene variants interacting with both inherited and somatic mtDNA variability.

Colloquium paper: bioenergetics, the origins of complexity, and the ascent of man

Complex structures are generated and maintained through energy flux. Structures embody information, and biological information is stored in nucleic acids. The progressive increase in biological complexity over geologic time is thus the consequence of the information-generating power of energy flow plus the information-accumulating capacity of DNA, winnowed by natural selection. Consequently, the most important component of the biological environment is energy flow: the availability of calories and their use for growth, survival, and reproduction. Animals can exploit and adapt to available energy resources at three levels. They can evolve different anatomical forms through nuclear DNA (nDNA) mutations permitting exploitation of alternative energy reservoirs, resulting in new species. They can evolve modified bioenergetic physiologies within a species, primarily through the high mutation rate of mitochondrial DNA (mtDNA)-encoded bioenergetic genes, permitting adjustment to regional energetic environments. They can alter the epigenomic regulation of the thousands of dispersed bioenergetic genes via mitochondrially generated high-energy intermediates permitting individual accommodation to short-term environmental energetic fluctuations. Because medicine pertains to a single species, Homo sapiens, functional human variation often involves sequence changes in bioenergetic genes, most commonly mtDNA mutations, plus changes in the expression of bioenergetic genes mediated by the epigenome. Consequently, common nDNA polymorphisms in anatomical genes may represent only a fraction of the genetic variation associated with the common "complex" diseases, and the ascent of man has been the product of 3.5 billion years of information generation by energy flow, accumulated and preserved in DNA and edited by natural selection.

Proteasome activity correlates with male BMI and contributes to the differentiation of adipocyte in hADSC

We have previously reported that 26S proteasome subunit mRNA expressions correlate with male body mass index (BMI). In this study, to investigate whether proteasome activities are correlated with BMI, we recruited 61 healthy young Japanese male subjects, measured proteasome activities in their plasma, and correlated them with their BMI and various metabolic factors. We found that among three different proteasome activities, chymotrypsin-like activity in plasma was positively correlated with BMI in healthy Japanese male subjects. Furthermore, we analyzed proteasome activity in vitro during the differentiation of human adipose-derived stem cell (hADSC) into mature adipocytes. In the early stage of differentiation, proteasome activity was at its highest level, and proteasome inhibitor could inhibit hADSC adipocyte differentiation. Our findings suggest that proteasome is an important controlling factor for the development of obesity and adipogenesis.

UCP1 -3826 AG+GG genotypes, adiponectin, and leptin/adiponectin ratio in severe obesity

BACKGROUND AND AIMS

Non-alcoholic fatty liver disease (NAFLD) and metabolic syndrome (MS) are well-recognized complications of obesity. This study was designed to evaluate the role of the UCP1 -3826 A>G polymorphism, adiponectin levels, leptin/adiponectin ratio (L/A), and main biochemical parameters in 102 unrelated severely obese adults [61 females and 41 males, median body mass index (BMI) = 47.8 kg/m2] with NAFLD, with (MS+) or without MS (MS-) from Southern Italy.

SUBJECT AND METHODS

The UCP1 polymorphism was tested by the TaqMan method, main biochemical parameters by routinary methods, adiponectin, and leptin serum levels by enzyme-linked immunosorbent assay. MS was diagnosed according to the American Heart Association criteria, liver steatosis was detected by ultrasound.

RESULTS

MS was present in 53% male and 66% female obese patients. Only total cholesterol (p=0.04 males and p=0.002 females) and L/A ratio (p=0.03 males) differed between MS+ and MS- obese patients. At multivariate analysis, severe liver steatosis was significantly associated with: UCP1 (AG+GG) genotypes [odds ratio-confidence interval (OR-CI): 4.25; 1.12-16.13], MS (OR-CI: 8.47; 1.78-40.25), low adiponectin levels (OR-CI: 0.92; 0.87-0.98), high alanine aminotransferase levels (OR-CI: 1.03; 1.00-1.06), age (ORCI: 1.08; 1.00-1.15), and male gender (OR-CI: 10.78; 1.61- 71.96).

CONCLUSION

In addition to traditional factors, total cholesterol and L/A ratio appear to contribute to MS characterization in severe obesity. Furthermore, the UCP1 (AG+GG) genotypes and low adiponectin levels could predispose to a more severe liver steatosis independently of MS presence. Based on our data, polymorphic UCP1 (AG+GG) obese patients with low adiponectin levels appear to be high-risk subjects for worsening of liver steatosis, a NAFLD, possibly requiring a second-step evaluation by liver biopsy.

The polymorphisms of UCP1 genes associated with fat metabolism, obesity and diabetes

Uncoupling protein 1 (UCP1), a 32-kDa protein located in the inner mitochondrial membrane, is abundant in brown adipose tissue, as a proton transporter in mitochondria inner membrane which uncouples oxidative metabolism from ATP synthesis and dissipates energy through the heat. UCP1 has been reported to play important roles for energy homeostasis in rodents and neonate of larger mammals including human. Recently, numerous candidate genes were searched to determine the genetic factors implicated in the pathogenesis of obesity, related metabolic disorders and diabetes. UCP-1, which plays a major role in thermogenesis, was suggested to be one of the candidates. This review summarizes data supporting the existence of brown adipocytes and the role of UCP1 in energy dissipation in adult humans, and the genetic variety association with the fat metabolism, obesity and diabetes.

Proteasome subunits mRNA expressions correlate with male BMI: implications for a role in obesity

Obesity as well as its associated chronic diseases and adverse health consequences such as type 2 diabetes mellitus, dyslipidemia, hypertension, and coronary artery disease are afflicting middle-aged adults and an ever greater number of children globally. We planned to investigate new obesity-related factors using proteomics approaches in a randomly selected three high and three low BMI samples of Epstein-Barr-transformed B (EBV-B) lymphoblastoid cell lines prepared from two groups of young Japanese men with different BMI. To search novel obesity-related factors, comparisons of protein expressions between high and low BMI groups were carried out by two-dimensional gel electrophoresis (2-DE). Gene transcripts of proteasome subunits found out from 2-DE were further determined by quantitative real-time PCR. Results from proteomics approach showed that the expression of proteasome alpha subunit type 5 (PSMA5) was significantly lower in the high BMI male group than in those with low BMI (P < 0.05). To validate these results, we expanded the study to include 20 more men and used real-time PCR to quantify the mRNA expression level in their EBV-B cells. Both PSMA5 and PSMA2 of EBV-B cells showed negative correlation with BMI. Furthermore, the mRNA levels measured in the peripheral blood B lymphocytes for many proteasome subunits in 75 healthy men and women showed significant negative correlation with BMI in healthy men. Our findings suggest that proteasome expression may play a key role in obesity.

Association of UCP1 genetic polymorphisms with blood pressure among Korean female subjects

Recent studies have provided some clues with regard to the relationship existing between uncoupling protein 1 (UCP1) and blood pressure in animal experiments. In an attempt to determine the genetic polymorphisms that are associated with blood pressure in humans, we have analyzed genetic polymorphisms in UCP1 gene. In this study, we assessed the association between UCP1 genotypes and systolic blood pressure (SBP) and diastolic blood pressure (DBP), in a population comprised of 832 Korean female subjects, using a general linear model, which was adjusted for age and body mass index (BMI). Among 4 genetic polymorphisms and the haplotypes constructed from them, haplotype3 of UCP1, UCP1-ht3[GAGA], evidenced significant associations with SBP (p=0.005) and DBP (p=0.013). However, this haplotype was not significantly associated with obesity phenotypes, including BMI or fat mass (p>0.05), thereby suggesting that its association with blood pressure was independent of obesity phenotypes.

The uncoupling protein-1 gene -3826A/G polymorphism and hypertension in Japanese subjects

BACKGROUND

The possible effects of the uncoupling protein-1 (UCP-1) gene -3826A/G polymorphism on hypertension (HT) have yet to be elucidated.

METHODS

A total of 578 Japanese subjects (231 males and 347 females, mean age 58.4 years) were enrolled in the study to investigate the association between HT and the -3826A/G polymorphism by genomic PCR and Bcl1-restriction fragment length polymorphism methods.

RESULTS

Multivariate logistic regression analysis for HT, adjusted for genotype (recessive model, AA+AG vs. GG) and other covariates such as cardiovascular risk factors [e.g., smoking, body mass index (BMI), dyslipidemia and diabetes] showed age [odds ratio (OR) 1.11 (95% confidence interval 1.08-1.13)] and BMI [OR 1.13 (1.06-1.21)] as independent significant factors. In the subgroup analysis, as well as age and BMI, GG genotype [OR 2.32 (1.08-4.99)] was also an independent significant factor for HT in males. Similarly, as well as age and BMI, GG genotype [OR 1.89 (1.00-3.57)] was also an independent significant factor for HT in the relatively older subgroup (> or =60 years).

CONCLUSIONS

The results suggest that the GG genotype may be associated with the presence of HT in Japanese males and older subjects. Further investigation is needed to confirm our hypothesis.

Relationship between A-3826G polymorphism in the promoter of the uncoupling protein-1 gene and high-density lipoprotein cholesterol in Japanese individuals: a cross-sectional study

BACKGROUND

A-3826G polymorphism within the promoter region of the uncoupling protein-1 (UCP-1) gene is possibly involved in the pathophysiology of obesity and metabolic disorders. However, the effects of UCP-1 A-3826G polymorphism on high-density lipoprotein cholesterol (HDL-C), a major contributor to atherosclerotic disease, still have not been established.

METHODS

A total of 298 healthy Japanese subjects (144 males and 154 females, mean age: 45.2 years) with a body mass index (BMI) of 20.0-30.0 kg/m(2), regular lifestyles, and receiving no medication were enrolled in the cross-sectional study to estimate the relationship of serum HDL-C levels with UCP-1 A-3826G polymorphism by genomic PCR and Bcl1-restriction fragment length polymorphism analysis. We used 1.04 mmol/L of HDL-C in Japanese males and 1.29 mmol/L in Japanese females as cut-off values of low HDL-cholesterolemia.

RESULTS

The genotype and allele frequencies of UCP-1 A-3826G polymorphism were similar to those previously reported in the Japanese population. In males, HDL-C levels of the GG genotype (1.75+/-0.49 mmol/L) were significantly higher than those found in the AA genotype (1.45+/-0.34 mmol/L, p=0.015). In females, the occurrence rate of low HDL-cholesterolemia was significantly different by genotype: a low prevalence in the GG genotype (15.4% in the AA, 4.8% in the AG, 15.4% in the GG genotype, p=0.022). Logistic regression analysis was used to identify risk factors for low HDL-cholesterolemia, with adjustments for age, gender, smoking, alcohol intake, BMI, hypertriglyceridemia, and genotype. The GG genotype was detected as being a significant associated factor (odds ratio =0.11 [95% confidence interval =0.01-0.90], p=0.01), in addition to BMI and the presence of hypertriglyceridemia.

CONCLUSIONS

These results suggest that the GG genotype may be an independent protective factor associated with low HDL-cholesterolemia in this population, although the role of the UCP-1 A-3826G polymorphism in HDL-C is complex and remains controversial. This hypothesis needs further investigation.

Association of UCP2 and UCP3 gene polymorphisms with serum high-density lipoprotein cholesterol among Korean women

Decreased serum high-density lipoprotein (HDL-C) cholesterol is a major risk factor for atherosclerosis and vascular disease. In this study, we assessed the association of 10 uncoupling protein (UCP) 2 and UCP3 polymorphisms with serum HDL cholesterol levels and atherogenic indexes among 658 Korean women. Among the 10 single nucleotide polymorphisms (SNPs) in the UCP2 and UCP3 genes, 2 SNPs in UCP2, -866G>A and +4787C>T (A55V) that were tightly linked (r(2) = 0.97), were significantly associated with decreased HDL cholesterol levels after Bonferroni correction (P = .003 in the recessive model). +4589C>T (Y210Y) in UCP3, a silent variation of Tyr210Tyr in exon 5, was also significantly associated with HDL cholesterol after multiple comparison correction. These 3 SNPs also exhibited some association with increases in the atherogenic index. Source-of-variation analysis revealed that -866G>A SNP accounted for 8.09% of the variation in serum HDL cholesterol levels independent of body mass index. We believe that our results may provide clues to the association of UCP genes with the risk of atherosclerosis through their effects on HDL cholesterol.