PPARgamma Gene Research Articles

Mo-P6:417 PRO12ALA polymorphism of the PPAR gamma gene is associated with postpradial hypertriglyceridaemia in non E3/E3 patients with the metabolic syndrome

Mo-P6:417 PRO12ALA polymorphism of the PPAR gamma gene is associated with postpradial hypertriglyceridaemia in non E3/E3 patients with the metabolic syndrome

ACDC/Adiponectin and PPAR‐γ Gene Polymorphisms: Implications for Features of Obesity

The main purpose of this study was to investigate associations of single-nucleotide polymorphisms (SNPs) in the adipocyte C1q and collagen domain-containing (ACDC) gene and its regulator, the nuclear peroxisome proliferator-activated receptor (PPAR)-gamma gene, with body fat mass and its topographical distribution in postmenopausal women. Participants were 1501 healthy women, 60 to 85 years old, who were genotyped for four SNPs in the ACDC gene (-11391G/A, -11377C/G, +45T/G, +276G/T) and the Pro12Ala SNP in the PPAR-gamma gene. Total body fat mass and the central to peripheral fat mass ratio (CFM/PFM ratio) were measured using DXA. Adiponectin and homeostasis model assessment of insulin resistance were measured in 287 subjects. The -11377C/G SNP was associated with adiponectin (p < 0.001) and the CFM/PFM ratio (p = 0.005); the G allele being associated with low adiponectin and high CFM/PFM ratio. Similar associations of adiponectin (p = 0.0001) and the CFM/PFM ratio (p = 0.002) characterized the 1_2 (G_G) promoter haplotype (11391G/A_-11377C/G). Genotype variation of SNP Pro12Ala was associated with total body fat mass (p = 0.04); women with GG being the most obese (p = 0.01). The Ala/Ala (GG) genotype of Pro12Ala SNP interacted with the CC genotype of SNP-11377C/G in the determination of BMI (p = 0.001), when analyzed using a codominant model. Polymorphisms in the ACDC gene are associated with body fat distribution, whereas the Pro12Ala polymorphism in PPAR-gamma is associated with overall adiposity, apparently in interaction with an ACDC promoter SNP.

Effects of Two Common Polymorphisms of Peroxisome Proliferator-Activated Receptor-γ Gene on Metabolic Syndrome

Peroxisome proliferator-activated receptor (PPAR)gamma is involved mainly in adipocyte differentiation and has been suggested to play an important role in the pathogenesis of insulin resistance and atherosclerosis. We investigated the frequencies of two common polymorphisms of PPARgamma gene, exon 6 C-->T substitution and exon B Pro12Ala in healthy subjects and analyzed the correlations between the different genotypes and insulin resistance, metabolic syndrome and cardiovascular risk factors. Anthropometric measurements, fasting glucose, insulin and lipid profiles were measured in 253 Korean females. Homeostatic model assessments and quantitative insulin sensitivity check indices were calculated. Metabolic syndrome was diagnosed according to the NCEP-ATP III guidelines and the Western Pacific Region of WHO for obesity criteria for waist circumference. Polymerase chain reaction (PCR)-restriction fragment-length polymorphism and real-time PCR were performed for genotyping of the DNAs. For C161T polymorphism, allele frequencies were 0.804 and 0.196 for T allele, and 0.947 for proline and 0.053 for alanine. There was no Ala12Ala homozygote in the population. No differences were seen in the mean values of age, body mass index (BMI), blood pressure, fasting blood glucose level, fasting insulin levels, HOMA and QUICKI among different genotypes when analyzed as a whole, except that subjects with Pro12Ala had significantly higher body weight than those with Pro12Pro genotype. However, mean BMI, percent body fat and weight showed significant differences between genotypes in younger age group (< or =50 years). Although overall prevalence of metabolic syndrome had no association with the genotypes, the prevalence of decreased high-density lipoprotein cholesterol component was lower in those with the T allele than in those with the CC genotype. There was no association of the genotypes with glucose tolerance status. When the subjects were divided into four groups according to the combination of the genetic alleles of the two polymorphisms, subjects having Pro12Ala and T allele, simultaneously, showed significantly higher mean weight than those without Ala allele. Pro12Ala polymorphism seems to affect body weight, similar to the previous studies, and the effect was potentiated with the presence of T allele of C161T polymorphism. Although either polymorphism failed to show significant association with insulin resistance, the fact that the prevalence of decreased HDL-C was lower in those with the T allele of C161T polymorphism suggests that this polymorphism might have a protective effect on atherosclerotic lipid profiles, which needs further investigation.

Syndromes d'insulinorésistance extrême génétiquement déterminés

To make a point about monogenic insulin resistance syndromes.Extreme insulin resistance syndromes are rare entities. The clinical and biological presentation is similar to that one of metabolic syndrome. Polycystic ovaries syndrome, non-alcoholic liver steatosis, acanthosis nigricans and overall, lipo-atrophic syndrome must be sought. Genetically determined forms are mainly linked to mutations of the insulin receptor gene and to lipoatrophic syndrome-linked mutations. The three syndromes related to mutations of the insulin receptor gene are Type A syndrome, first described by Kahn in young women, whereas leprechaunism and Rabson-Mendenhall syndromes are of neonatal onset. Main insulin resistance syndromes associated with lipo-atrophy are 1) Berardinelli-Seip or congenital generalized lipo-atrophic syndrome linked to mutations of seipin or AGPAT2 gene, 2) Dunnigan or partial familial lipoatrophic syndrome linked to mutations of lamin A/C, or sometimes PPAR gamma gene, and 3) acro-mandibular dysplasia and Köbberling syndrome.In conclusion, an early onset of insulin resistance, especially in association with lipodystrophy must suggest a monogenic insulin resistance syndrome. Outstanding advances in insulin resistance pheno- and genotype identification, despite incomplete yet, offers a better understanding of insulin resistance, atherosclerosis and ageing mechanisms, that should lead to therapeutic improvement.

The influence of the Pro12Ala mutation of PPARγ2 receptor gene on β-cells restoration and insulin resistance in type 2 diabetes with hypertension

The aim of this investigation was to determine whether a PPARgamma2 Pro12Ala polymorphism was associated with insulin resistance, beta-cell function and hypertension in Chinese populations. 289 unrelated Chinese subjects first diagnosed Type 2 diabetes (HbAC1 < 6.0) were investigated, including 132 hypertensive diabetic (HTD) subjects, 157 normotensive diabetic (NTD) subjects. Blood pressure and anthropometric measurements were collected from all participants, as well as several venous blood samples during oral glucose tolerance test (OGTT). Biochemical measurements (high-density lipoprotein (HDL) and low-density lipoprotein-cholesterol (LDL), triglycerides) and PPARgamma2 Pro12Ala genotype were also determined. And insulin resistance and beta-cells function was assessed by HOMA-IR and HOMA-beta respectively. The frequency of subjects bearing the Pro12Ala was lower in the hypertension group (3.03%) than in the non-hypertension group (5.7%) (P < 0.05) after adjusted for age, BMI and gender. Hypertensive diabetic Pro12Ala subjects had lower fasting plasma glucose level (P = 0.0127), and better glucose tolerance 60 min after oral glucose (P = 0.0361). Moreover, plasma insulin concentrations at 60 min was lower than those without A variant (P = 0.0275), and both hypertensive Ala/Pro in HOMA-beta (P = 0.0455) and AUC for insulin (P = 0.0473) were higher, and HOMA-IR was lower (P = 0.0375) as compared with hypertensive Pro/Pro subjects. No association was observed between Pro12Ala genotype and BMI, total cholesterol, HDL- cholesterol or triglycerides in either group. Our findings suggested that the Ala 12 allele of the PPARgamma2 gene may improve insulin resistance and ameliorate beta-cell function reserves in T2DM with hypertension, and protect patients from hypertension in T2DM. As an important thrifty gene, environment factors may exerts an effect of PPAR gamma2 on glucose homeostasis and insulin resistance.

An inverse relationship between peroxisome proliferator–activated receptor γ and allergic airway inflammation in an allergen challenge model

Peroxisome proliferator-activated receptor gamma (PPAR-gamma) expression has not been evaluated in bronchoalveolar lavage (BAL) cells from allergic asthmatic patients. To determine whether inappropriate down-regulation of PPAR-gamma in alveolar macrophages may contribute to persistent airway inflammation in allergic asthma. We used segmental allergen challenge as a model of in vivo experimental allergic asthmatic exacerbation and airway inflammation. PPAR-y gene expression was evaluated at baseline and 24 hours later in asthmatic patients and controls using real-time polymerase chain reaction. Immunofluorescence was used to determine cellular location of the PPAR-gamma protein. We demonstrate for the first time to our knowledge that PPAR-gamma messenger RNA and protein, which are highly expressed in alveolar macrophages of healthy individuals, are significantly reduced in asthmatic patients after segmental allergen challenge. In allergic asthmatic patients (n=9), PPAR-gamma gene expression decreased significantly from baseline to postchallenge BAL (median decrease, 45%; P = .008). Furthermore, immunofluorescence staining demonstrated that PPAR-gamma protein was associated with alveolar macrophages and not with inflammatory eosinophils and neutrophils. Results implicate down-regulation of PPAR-gamma in BAL cells as a potential factor in dysregulation of lung homeostasis in asthmatic patients. The present findings suggest that PPAR-gamma agonists could have a future role in asthma therapy and warrant further study.

Relation of weight maintenance and dietary restraint to peroxisome proliferator–activated receptor γ2, glucocorticoid receptor, and ciliary neurotrophic factor polymorphisms

Genetic variation in the peroxisome proliferator-activated receptor gamma2 (PPARgamma2), glucocorticoid receptor (GRL), and ciliary neurotrophic factor (CNTF) genes may play a role in the etiology of obesity. We examined biological, psychological, and genetic determinants associated with weight maintenance (WM) after weight loss. Subjects (n = 120) followed a 6-wk diet and then a 1-y period of WM. Body weight (BW), body composition, leptin concentration, attitude toward eating (measured with the Three-Factor Eating Questionnaire), physical activity, and the polymorphisms of the PPARgamma2, GRL, and CNTF genes were measured. BW loss was 7.0 +/- 3.1 kg. After 1 y, 21 subjects showed successful WM (<10% regain); 99 were unsuccessful (> or =10% regain). Compared with unsuccessful subjects, successful subjects had a higher increase in dietary restraint over time (4.8 +/- 5.0 and 1.8 +/- 3.9, respectively; P < 0.01) but significantly less sensation of general hunger (-4.0 +/- 4.9 and -1.2 +/- 2.7, respectively; P < 0.05). Successful subjects had a significantly different frequency distribution for the PPARgamma2 (P = 0.05) and GRL (P < 0.05) genes than did unsuccessful subjects. The more successful genotypes showed a higher baseline body mass index and waist circumference (PPARgamma2), a greater decrease in disinhibition of dietary restraint (GRL), and less sensation of hunger (GRL). The G/G genotype (GRL) was an independent predictor of successful WM. The different genotypes of the PPARgamma2 and GRL genes contribute to WM, either directly (GRL) or indirectly (PPARgamma2 and GRL) via baseline body mass index and waist circumference, and to changes in Three-Factor Eating Questionnaire scores.

Effects of Pro12Ala polymorphism of peroxisome proliferator-activated receptor γ2 gene on rosiglitazone response in type 2 diabetes

The aim of this study was to examine the effects of the Pro12Ala polymorphism of the peroxisome proliferator-activated receptor (PPAR) gamma2 gene on the response to rosiglitazone in patients with type 2 diabetes mellitus. A total of 198 patients with type 2 diabetes mellitus were treated with rosiglitazone (4 mg/d) for 12 weeks without a change in previous medications. All patients were genotyped for the PPARgamma2 Pro12Ala polymorphism. The Ala12 allele frequency was 0.04. Of the 198 patients, 183 had the Pro12Pro genotype and 15 had the Pro12Ala genotype. The Ala12Ala genotype was not observed. The decrease in fasting plasma glucose level was significantly greater in subjects with the Ala12 allele than in those without the allele (50.6 +/- 27.8 mg/dL versus 24.3 +/- 41.9 mg/dL, P = .026). In addition, the decrease in hemoglobin A(1c) level was significantly greater in subjects with the Ala12 allele than in those without the allele (1.41% +/- 1.47% versus 0.57% +/- 1.16%, P = .015). There was a significant difference in the response rate to rosiglitazone treatment between the Pro12Pro group and the Pro12Ala variant group (43.72% versus 86.67%, P = .002). Patients with the Pro12Ala genotype in the PPARgamma2 gene had a better therapeutic response to rosiglitazone than did patients with the Pro12Pro genotype. The genetic variations in the PPARgamma2 gene can affect the response to rosiglitazone treatment in patients with type 2 diabetes mellitus.

Influence of the C161T but not Pro12Ala polymorphism in the peroxisome proliferator‐activated receptor‐gamma on colorectal cancer in an Indian population

The aim of the present study was to investigate associations between Pro12Ala and C161T polymorphisms in the peroxisome proliferator-activated receptor-gamma (PPAR-gamma) gene and colorectal cancer (CRC) risk. We recruited 301 newly diagnosed CRC patients and 291 healthy control subjects at the Madras Cancer Institute in Chennai, India, from 1999 to 2001. Genotypes of the Pro12Ala and C161T polymorphisms were determined using the PCR-RFLP method. After adjustment for age, sex, smoking habit, family history and family income, an increased risk of CRC was observed for the C/T + T/T genotype compared to the C/C genotype of the C161T polymorphism (odds ratio = 1.61, 95% confidence interval: 1.10-2.36), whereas no significant association was found for Pro12Ala (odds ratio = 1.06, 95% confidence interval: 0.70-1.61). Analysis with estimated haplotypes showed a significant difference in haplotype frequencies between cases and controls (chi(2) = 11.62, P = 0.009, d.f. = 3). The relationship between the two polymorphisms and CRC risk was not significantly modified by dietary intake of fish. Although the biological mechanisms of the observed association remain to be elucidated, our findings suggest that the C161T polymorphism of the PPAR-gamma gene is related to risk of CRC. Further research is needed to investigate functional implications of polymorphisms of the PPAR-gamma gene in CRC development.

The Peroxisome Proliferator-activated Receptor-γ Regulates Murine Pyruvate Carboxylase Gene Expression in Vivo and in Vitro

Pyruvate carboxylase (PC) plays a crucial role in various metabolic pathways, including gluconeogenesis, lipogenesis, and glucose-induced insulin secretion. Here we showed for the first time that the PC gene is transcriptionally regulated by peroxisome proliferator-activated receptor-gamma (PPARgamma) in vitro and in vivo in white and brown adipose tissue. PC mRNA and protein are markedly increased during differentiation of 3T3-L1 cells and HIB-1B, in parallel with the expression of the adipogenic transcription factors, CCAAT-enhancer binding protein alpha, PPARgamma1, and PPARgamma2. Tumor necrosis factor-alpha, a cytokine that blocks differentiation of 3T3-L1 cells, suppressed PC expression. Co-transfection studies in 3T3-L1 preadipocytes or HEK293T cells with a 2.3-kb promoter fragment of mouse PC gene linked to a luciferase reporter construct and with plasmids overexpressing retinoid X receptor alpha/PPARgamma1 or retinoid X receptor alpha/PPARgamma2 showed a 6-8-fold increase above the basal promoter activity. Furthermore, treatment of these transfected cells with the PPARgamma agonist doubled the promoter activity. Mutation of the putative PPAR-response element-(-386/-374) of this 2.3-kb PC promoter fragment abolished the PPARgamma response. Gel shift and chromatin immunoprecipitation assays demonstrated that endogenous PPARgamma binds to this functional PPAR-response element of the PC promoter. Mice with targeted disruption of the PPARgamma2 gene displayed approximately 50-60% reduction of PC mRNA and protein in white adipose tissue. Similarly, in brown adipose tissue of PPARgamma2-deficient mice subjected to cold exposure, PC mRNA was 40% lower than that of wild type mice. Impaired in vitro differentiation of white adipocytes of PPARgamma2 knock-out mice was also associated with a marked reduction of PC mRNA. Our findings identified PC as a PPARgamma-regulated gene and suggested a role for PPARgamma regulating intermediary metabolism.

Collecting duct-specific deletion of peroxisome proliferator-activated receptor gamma blocks thiazolidinedione-induced fluid retention.

The peroxisome proliferator-activated receptor subtype gamma (PPARgamma) ligands, namely the synthetic insulin-sensitizing thiazolidinedione (TZD) compounds, have demonstrated great potential in the treatment of type II diabetes. However, their clinical applicability is limited by a common and serious side effect of edema. To address the mechanism of TZD-induced edema, we generated mice with collecting duct (CD)-specific disruption of the PPARgamma gene. We found that mice with CD knockout of this receptor were resistant to the rosiglitazone- (RGZ) induced increases in body weight and plasma volume expansion found in control mice expressing PPARgamma in the CD. RGZ reduced urinary sodium excretion in control and not in conditional knockout mice. Furthermore, RGZ stimulated sodium transport in primary cultures of CD cells expressing PPARgamma and not in cells lacking this receptor. These findings demonstrate a PPARgamma-dependent pathway in regulation of sodium transport in the CD that underlies TZD-induced fluid retention.

The effect of PPARγ ligands on UV‐ or chemically‐induced carcinogenesis in mouse skin

Peroxisome proliferator-activated receptor gamma (PPARgamma) is a ligand activated transcription factor. There have been suggestions that PPARgamma ligands may have utility in preventing tumor development in rodent mammary glands and colon. The recent finding that mice lacking one allele of the PPARgamma gene were significantly more susceptible to 7,12-dimethylbenz[a]anthracene (DMBA)-induced skin carcinogenesis compared to wild-type mice highlights mouse skin as another potential organ in which PPARgamma ligands may be effective as chemopreventive agents. In this study, we assessed the effect of two PPARgamma ligands (rosiglitazone and troglitazone) on UV and DMBA/12-O-tetradecanoylphorbol-13-acetate (TPA)-induced mouse skin carcinogenesis, two of the most commonly used mouse skin carcinogenesis models. Unexpectedly, neither rosiglitazone (dietary 200 ppm) nor troglitazone (topical 100 microg) significantly inhibited UV-induced skin tumor development in SKH-1 hairless mice. Likewise, dietary rosiglitazone did not statistically significantly inhibit DMBA/TPA-induced skin tumor development. Interestingly, dietary troglitazone significantly inhibited basal level keratinocyte proliferation as shown by 5-bromo-2'-deoxyuridine (BrdU) labeling, but it had no effect on TPA-induced epidermal cell proliferation. Northern blot analysis showed that PPARgamma expression was extremely low in normal mouse epidermis and was virtually undetectable in skin tumors. Collectively, our data suggest that PPARgamma ligands may not be useful in the prevention of chemically or UV-induced skin tumors.

The peroxisome proliferator activated receptorφ 2 (PPARφ 2) Pro12Ala variant: lack of association with type 2 diabetes in obese and non obese Tunisian patients

Peroxisome proliferator activated receptorgamma2 (PPARgamma2) is a nuclear receptor that regulates adipocyte differentiation, lipid metabolism and probably insulin sensitivity. There have been several reports on the relationship between the PPARgamma2 Pro12Ala genotype and the development of obesity or type 2 diabetes. We designed a case-controlled study to investigate the potential association of the genetic variation of the PPARgamma2 gene with type 2 diabetes in Tunisians. We used the polymerase chain reaction and restriction enzyme digestion to characterize the variation of the Pro12Ala polymorphism of the PPARgamma2 gene in 242 unrelated Tunisian patients with type 2 diabetes and 246 healthy control subjects. Analysis of the Pro12Ala polymorphism of the PPARgamma2 gene in patients with type 2 diabetes and in control subjects revealed no significant differences in the PPARgamma2 allele frequencies between diabetic patients and control subjects. However the PPARgamma2 Ala12 allele was found significantly associated with a high level of systolic blood pressure in diabetic patients. Stratification of diabetic patients on obese and non obese subjects showed non significant differences in the PPARgamma2 Ala12 frequency between the two groups. These results suggest that the PPARgamma2 gene is unlikely a major gene for type 2 diabetes mellitus or obesity in Tunisian subjects.

Effect of the peroxisome proliferator-activated receptor-γ C161T polymorphism on lipid profile in Brazilian patients with Type 2 diabetes mellitus

The aim of the present study was to examine the effects of the C161T polymorphism of the peroxisome proliferator-activated receptor gamma (PPARgamma) gene in Brazilian subjects with Type 2 diabetes mellitus (T2DM) and controls residing in Sao Paulo City, Brazil. Genomic DNA was obtained from 207 patients with T2DM and 170 unrelated normoglycemic individuals (CG). Anthropometric data included: body mass index, waist, hip, waist-to-hip ratio; biochemical parameters: fasting plasma glucose, total cholesterol, HDL- and LDL-cholesterol, triglycerides, glycated hemoglobin and insulin. Systolic and diastolic blood pressure was also measured. Screening for mutations in the entire coding region of the PPARgamma gene was carried out by PCR, single strand conformational polymorphism analysis (SSCP) and sequencing. C161T polymorphism was analyzed by PCR-RFLP. The C161T polymorphism was the only variant found in exon 6 of the PPARgamma gene. The frequency of the 161T allele in T2DM (0.10) was similar to that found in CG (0.07, p=0.210). Serum triglycerides (p=0.040), VLDL-cholesterol (p=0.040) and Atherogenic Index of Plasma (AIP; p=0.003) were significantly lower in 161T allele carriers than non-carriers in women of the T2DM group. Our results show that the C161T polymorphism in the PPARgamma gene is not associated with variables related to T2DM or insulin resistance in the Brazilian population. However, a reduction of serum triglycerides and AIP was observed in women with 161T allele of the C161T polymorphism of the PPARgamma gene.

The effects of C161→T polymorphisms in exon 6 of peroxisome proliferator-activated receptor-γ gene on bone mineral metabolism and serum osteoprotegerin levels in healthy middle-aged women

We evaluated the association of different genotypes in C161-->T substitution in exon 6 of peroxisome proliferator-activated receptor-gamma (PPARgamma) gene with bone turnover markers, bone mineral density (BMD), and serum osteoprotegerin (OPG) in female subjects to reveal the role of PPARgamma in bone. In 263 healthy Korean women (mean age 52 years), anthropometric measurements were taken along with measurements of lumbar spine and femoral neck BMD, bone turnover markers, such as alkaline phosphatase, serum calcium, phosphorus, 24-hour urine calcium, phosphorus excretion, and urine deoxypyridinoline. Serum follicular stimulating hormone levels were measured and serum OPG levels were measured with the enzyme-linked immunosorbent assay method. Polymerase chain reaction-restriction fragment length polymorphism was performed. Allele frequencies were 0.804 for the C allele and 0.196 for the T allele. There were no differences in mean age, body mass index, BMD, and bone turnover markers among different genotypes, and the subjects with T alleles had significantly lower serum OPG levels. There were no differences in the prevalence of metabolic bone diseases according to the genotypes. When analyzed according to the menopausal status, only postmenopausal subjects with T alleles showed significantly lower serum OPG levels. The frequencies of C161-->T substitution in exon 6 of the PPARgamma gene in Korean females were similar to other races and women with T alleles showed significantly lower serum OPG levels and it was especially noted for postmenopausal subjects, which supports the possible concurrent association of PPARgamma and OPG with estrogen status in female subjects.

The peroxisome proliferator activated receptor gamma Pro12Ala polymorphism is associated with a lower hirsutism score and increased insulin sensitivity in women with polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is characterized by hyperandrogenism and chronic anovulation. The genetic background of the insulin resistance frequently associated with PCOS is unclear. To examine the influe nce of the Pro12Ala polymorphism of the peroxisome proliferator activated receptor gamma (PPARgamma), which is thought to play a role in the regulation of insulin sensitivity, on endocrine and metabolic parameters in PCOS patients. PPARgamma alleles were analysed in 102 PCOS patients (age 27 +/- 5.3 years) and 104 age matched control women. PCOS was defined by the NIH-criteria as the presence of chronic oligo- or anovulation and hyperandrogenism. Family history and clinical parameters were evaluated by personal interview and physical examination, parameters of insulin resistance [homeostasis model assessment (HOMA) and Matsuda-index] were evaluated with a glucose tolerance test. Seventy-nine (77.5%) PCOS patients were carriers of the wild-type PPARgamma allele (Pro/Pro), while 23 (22.5%) had at least one Ala allele (X/Ala), with an equal distribution in controls. X/Ala PCOS women were more insulin-sensitive, evidenced by lower fasting insulin, HOMA index and insulin secretion. Differences in insulin resistance did not depend on body mass index. The genotype had no influence on lipid status, leptin, adiponectin, ghrelin, or family history of type 2 diabetes. A significantly lower proportion of Pro/Ala patients had hirsutism and they had on average lower hirsutism scores than Pro/Pro patients. No relationship was found between the Pro/Ala polymorphism and other signs of hyperandrogenism. The Pro12Ala polymorphism of the PPARgamma gene is associated with increased insulin sensitivity and lower hirsutism scores in PCOS women.

Gly482Ser polymorphism of the peroxisome proliferator-activated receptor-γ coactivator-1 gene might be a risk factor for diabetic retinopathy in Slovene population (Caucasians) with type 2 diabetes and the Pro12Ala polymorphism of thePPARγ gene is not

The peroxisome proliferator-activated receptor-gamma (PPARgamma) gene has been recently associated with type 2 diabetes, obesity and traits depending on VEGF expression (e.g. retinopathy). The PPARgamma gene and its coactivator, the peroxisome proliferator-activated receptor-gamma coactivator-1 (PPARGC1) gene, have been implicated to be involved in glucose uptake and altered lipid oxidation. We therefore hypothesized that the Gly482Ser polymorphism of the PPARGC1 gene and Pro12Ala polymorphism of the PPARgamma gene might confer susceptibility to diabetic retinopathy in type 2 diabetes. The aim of this study was to investigate the association between the Pro12Ala polymorphism in the PPARgamma gene and Gly482Ser polymorphism in the PPARGC1 gene and the development of diabetic retinopathy in the Slovene population (Caucasians) with type 2 diabetes. One hundred and sixty subjects with type 2 diabetes and diabetic retinopathy were compared with 101 diabetic subjects without diabetic retinopathy. Chi-square test was used to compare discrete variables, and continuous clinical data were compared by unpaired students t - test. A significantly higher frequency of the AA genotype of the Gly482Ser polymorphism of the PPARGC1 gene was found in the patients with diabetic retinopathy compared to the patients without diabetic retinopathy (14.4% vs 5.9%; p = 0.035), whereas the Pro12Ala polymorphism of the PPARgamma gene failed to yield an association with diabetic retinopathy. The present study demonstrates that the AA genotype of the Gly482Ser polymorphism in the PPARGC1 gene might be a risk factor for diabetic retinopathy in the Slovene population (Caucasians) with type 2 diabetes (odds ratio 2.7, 95% confidence interval 1.0-6.8), whereas the Pro12Ala polymorphism of the PPARgamma gene failed to confer susceptibility to diabetic retinopathy.

Implication of the Pro12Ala polymorphism of the PPAR-gamma 2gene in type 2 diabetes and obesity in the French population

BackgroundThe Pro12Ala Single Nucleotide Polymorphism (SNP) of the Peroxisome Proliferator-Activated Receptor gamma 2 (PPAR-gamma 2) has been associated with insulin resistance and type 2 diabetes (T2D) and also inconsistently with obesity. The aim of this study was to evaluate the impact of this SNP with regards to T2D and childhood and adult obesity in the French Caucasian population.MethodsWe conducted three independent case/control studies encompassing 2126 cases and 1124 controls.ResultsWe found a significant association between PPAR-gamma 2 Pro12Ala SNP and T2D (p = 0.04, OR = 1.37), which was stronger when the T2D cohort was stratified according to the obesity status (p = 0.03, OR = 1.81 in obese T2D subjects). In contrast, there was no association between the Pro12Ala SNP and childhood and adulthood obesity. In normal glucose tolerant obese adults (but not in lean subjects), the Pro12 allele was associated with a significant increase in fasting insulin levels (p = 0.01), and in insulin resistance estimated by the Homeostasis Model Assessment of Insulin Resistance (HOMA-IR) (p = 0.003), after adjustment for age, gender and BMI. We didn't detect evidence for an interaction effect between the Pro12Ala SNP and the obesity status with respect to the HOMA-IR index in normal glucose tolerant children, but we found a borderline interaction (p = 0.06) in normal glucose tolerant adults.ConclusionOur results showed that the Pro12Ala polymorphism is not associated with childhood or adult obesity in the French Caucasian population. In contrast, we confirm a contribution of the PPAR-gamma 2 Pro12 allele in the genetic risk forT2D, especially in obese subjects, where this allele worsens insulin resistanceand increases fasting insulin levels.

A possible association of Pro12Ala polymorphism in peroxisome proliferator-activated receptor γ2 gene with obesity in native Javanese in Indonesia

Peroxisome proliferators-activated receptor gamma (PPAR gamma) is a nuclear hormone receptor that serves as a master regulator of adipocytes-specific genes contributing to adipocytes differentiation, susceptibility to obesity, and insulin sensitivity. The substitution of proline to alanine at codon 12 of the PPAR gamma2 gene (Pro12Ala polymorphism) is most frequently identified and the associations with diabetes, obesity, and other clinical parameters have been reported and discussed in several ethnic groups. Among native Javanese ethnicity, however, there is no report about this polymorphism. Aims of this study were to estimate the allele frequency of the Pro12Ala polymorphism of PPAR gamma2 gene among native Javanese in Indonesia and to investigate the relationship between this polymorphism and obesity or diabetes. This study included 540 native Javanese subjects consisting of 337 diabetic patients and 203 normal glucose tolerance subjects. Both groups included totally 160 obese subjects (body mass index > or = 25 kg/m(2)). PCR-restriction fragment length polymorphism was used for the genotype determination. The allele frequency of Pro12Ala polymorphism in PPAR gamma2 gene among native Javanese is lower than that in other ethnic groups. No association is seen between the Pro12Ala and diabetes (0.01 vs 0.017%, p = 0.404), a trend of the higher BMI was observed in Pro12Ala carriers in nondiabetic subjects, although this association is limited by small numbers. In this study, no association is seen between the Pro12Ala polymorphism in PPAR gamma2 gene and diabetes; a weak association with obesity is seen.

Identification and characterization of novel peroxisome proliferator‐activated receptor‐gamma (PPAR‐γ) transcriptional variants in pig and human

The peroxisome proliferator-activated receptor-gamma (PPAR-gamma) is a member of the steroid/thyroid/retinoid receptor superfamily, and is primarily expressed in fat tissue. To date, two major PPAR-gamma isoforms have been identified in pig, PPAR-gamma1 and PPAR-gamma2. Porcine PPAR-gamma1a consists of two leader exons, designated A1 and A2, followed by six exons containing the open reading frame. Here, we report the isolation and characterization of three novel PPAR-gamma1 transcripts. PPAR-gamma1b is derived from exon A1, with exon A2 spliced out. PPAR-gamma1c and PPAR-gamma1d are derived from the new exon, A', containing exon A2 (gamma1c) or without exon A2 (gamma1d). Based on PCR analysis of PAC clones that included sequences from the 5'-untranslated region of the PPAR-gamma gene, the new A' exon is located between the known exons A1 and A2. We also isolated the human homologue to exon A', as well as the two new PPAR-gamma1c and -gamma1d splice variants, from human adipose tissue. Studies of the expression of porcine PPAR-gamma by real time reverse transcription-polymerase chain reaction analysis show that transcripts derived from exon A1 were not expressed at significantly different levels in visceral fat (lamina subserosa) or subcutaneous fat (back fat, inner and outer layer). In contrast, exon A'-derived transcripts were expressed at progressively higher levels in the inner and outer layers of subcutaneous fat than in visceral fat. The same expression pattern was also observed for PPAR-gamma2. We hypothesize that there are three promoters, which differentially regulate PPAR-gamma1 and PPAR-gamma2 gene expression, depending on the specific localization of the fat tissue.