Association of lipoprotein lipase gene polymorphisms with obesity and type 2 diabetes in an Asian Indian population

Interaction between genetic risk score and dietary fat intake on lipid-related traits in Brazilian young adults

The occurrence of dyslipidaemia, which is an established risk factor for cardiovascular diseases, has been attributed to multiple factors including genetic and environmental factors. We used a genetic risk score (GRS) to assess the interactions between genetic variants and dietary factors on lipid-related traits in a cross-sectional study of 190 Brazilians (mean age: 21 ± 2 years). Dietary intake was assessed by a trained nutritionist using three 24-h dietary recalls. The high GRS was significantly associated with increased concentration of TAG (beta = 0·10 mg/dl, 95 % CI 0·05-0·16; P < 0·001), LDL-cholesterol (beta = 0·07 mg/dl, 95 % CI 0·04, 0·11; P < 0·0001), total cholesterol (beta = 0·05 mg/dl, 95 % CI: 0·03, 0·07; P < 0·0001) and the ratio of TAG to HDL-cholesterol (beta = 0·09 mg/dl, 95 % CI: 0·03, 0·15; P = 0·002). Significant interactions were found between the high GRS and total fat intake on TAG:HDL-cholesterol ratio (Pinteraction = 0·03) and between the high GRS and SFA intake on TAG:HDL-cholesterol ratio (Pinteraction = 0·03). A high intake of total fat (>31·5 % of energy) and SFA (>8·6 % of energy) was associated with higher TAG:HDL-cholesterol ratio in individuals with the high GRS (beta = 0·14, 95 % CI: 0·06, 0·23; P < 0·001 for total fat intake; beta = 0·13, 95 % CI: 0·05, 0·22; P = 0·003 for SFA intake). Our study provides evidence that the genetic risk of high TAG:HDL-cholesterol ratio might be modulated by dietary fat intake in Brazilians, and these individuals might benefit from limiting their intake of total fat and SFA.

Impact of Lipid Genetic Risk Score and Saturated Fatty Acid Intake on Central Obesity in an Asian Indian Population

Abnormalities in lipid metabolism have been linked to the development of obesity. We used a nutrigenetic approach to establish a link between lipids and obesity in Asian Indians, who are known to have a high prevalence of central obesity and dyslipidaemia. A sample of 497 Asian Indian individuals (260 with type 2 diabetes and 237 with normal glucose tolerance) (mean age: 44 ± 10 years) were randomly chosen from the Chennai Urban Rural Epidemiological Study (CURES). Dietary intake was assessed using a previously validated questionnaire. A genetic risk score (GRS) was constructed based on cholesteryl ester transfer protein (CETP) and lipoprotein lipase (LPL) genetic variants. There was a significant interaction between GRS and saturated fatty acid (SFA) intake on waist circumference (WC) (Pinteraction = 0.006). Individuals with a low SFA intake (≤23.2 g/day), despite carrying ≥2 risk alleles, had a smaller WC compared to individuals carrying <2 risk alleles (Beta = −0.01 cm; p = 0.03). For those individuals carrying ≥2 risk alleles, a high SFA intake (>23.2 g/day) was significantly associated with a larger WC than a low SFA intake (≤23.2 g/day) (Beta = 0.02 cm, p = 0.02). There were no significant interactions between GRS and other dietary factors on any of the measured outcomes. We conclude that a diet low in SFA might help reduce the genetic risk of central obesity confirmed by CETP and LPL genetic variants. Conversely, a high SFA diet increases the genetic risk of central obesity in Asian Indians.

Genetic association of LPL rs326 with BMI among the Kuwaiti population

Supplemental Digital Content is available in the text.

Lipoprotein lipase is a key enzyme in lipid metabolism with reported variants associated with obesity, hypertension, type 2 diabetes, and coronary heart disease. This study was performed to investigate the association between common lipoprotein lipase single nucleotide polymorphisms and metabolic disorders in a sample of Kuwaiti cohort (n = 494). Five lipoprotein lipase variants (rs1801177, rs295, rs326, ss2137497749, and ss2137497750) across the lipoprotein lipase gene were genotyped by real-time PCR employing the TaqMan allele discrimination assay. Genotype, allelic frequencies, and Hardy-Weinberg Equilibrium were determined for each variant in the cohort followed by multivariate and logistic regression analysis. A novel finding was observed for the G allele of single nucleotide polymorphism rs326 which was associated with increased BMI after adjusting for age and sex (β = 1.04; 95% confidence interval = 0.15–1.94; P = 0.02). Moreover, a significant difference in the distribution of the minor C allele of rs295 among coronary heart disease subjects compared with noncoronary heart disease, however, this significance was diminished after controlling for age, sex, and BMI. This study demonstrated that lipoprotein lipase rs326 may be indicative for the increased risk of obesity and possibly rs295 for coronary heart disease. The findings are also in agreement with other reports suggesting that intronic variants are important genetic markers in association studies. The findings warrant further studies in a large cohort to confirm and validate the results presented.

Pharmacogenomics and Personalized Medicine in Type 2 Diabetes Mellitus: Potential Implications for Clinical Practice

Type 2 diabetes mellitus (T2DM) is the most common form of diabetes, and is rising in incidence with widespread prevalence. Multiple gene variants are associated with glucose homeostasis, complex T2DM pathogenesis, and its complications. Exploring more effective therapeutic strategies for patients with diabetes is crucial. Pharmacogenomics has made precision medicine possible by allowing for individualized drug therapy based on a patient's genetic and genomic information. T2DM is treated with various classes of oral hypoglycemic agents, such as biguanides, sulfonylureas, thiazolidinediones, meglitinides, DPP4 inhibitors, SGLT2 inhibitors, α-glucosidase inhibitors, and GLP1 analogues, which exhibit various pharmacogenetic variants. Although genomic interventions in monogenic diabetes have been implemented in clinical practice, they are still in the early stages for complex polygenic disorders, such as T2DM. Precision DM medicine has the potential to be effective in personalized therapy for those suffering from various forms of DM, such as T2DM. With recent developments in genetic techniques, the application of candidate-gene studies, large-scale genotyping investigations, genome-wide association studies, and "multiomics" studies has begun to produce results that may lead to changes in clinical practice. Enhanced knowledge of the genetic architecture of T2DM presents a bigger translational potential. This review summarizes the genetics and pathophysiology of T2DM, candidate-gene approaches, genome-wide association studies, personalized medicine, clinical relevance of pharmacogenetic variants associated with oral hypoglycemic agents, and paths toward personalized diabetology.

Association between the lipoprotein lipase rs1534649 gene polymorphism in intron one with Body Mass Index and High Density Lipoprotein-Cholesterol

Lipoprotein lipase (LPL) is an enzyme involved in lipid metabolism and distribution of fatty acids hence its role in the initiation and development of dyslipidemia and adiposity. Single nucleotide polymorphisms (SNPs) across the LPL gene have been associated with dyslipidemia, however, the association with obesity has been limited towards specific populations. This study examined the association between LPL gene polymorphisms with plasma lipid levels and body mass index (BMI) in the Kuwaiti population. We examined a total of 486 adults (303 and 183 females and males respectively) with plasma lipid levels and BMI. DNA samples were genotyped for two LPL gene polymorphisms (rs1534649 and rs28645722) using TaqMan allelic discrimination. The relationship between the genotypes with both plasma lipid levels and BMI were assessed using linear regression using “SNPassoc” package from R statistical software. Using an additive genetic model, linear regression analysis showed the T-allele of rs1534649 to be associated with increased BMI in a dose-dependent trend β = 2.13 (95% CI 1.33–2.94); p = 1.7 × 10⁻⁷. In addition, a borderline significance was observed between the T-allele and low levels of high density lipoprotein-cholesterol β = −0.04 (95% CI −0.08, −0.006); p = 0.02. There were no associations between rs28645722 and plasma lipid levels (p > 0.05). However, a trend was observed between the A-allele and increased BMI β = 1.75 (95% CI 0.14–3.35); p = 0.03. Our study shows intron one polymorphism rs1534649 to increase the risk of obesity and dyslipidemia. Our findings warrant further investigation of the mechanism of LPL on the development of obesity along with the role of intron one and its impact on LPL gene activity.

Association of NFκβ, TNFα, IL-6, IL-1β, and LPL Polymorphisms with Type 2 Diabetes Mellitus and Biochemical Parameters in a Mexican Population

Chronic low-grade inflammation is strongly related to the etiology of diabetes mellitus type 2 (T2DM), and the expression of inflammatory cytokines may be modulated by polymorphisms located in the regulatory regions of the NFκβ, IL-1β, IL-6, TNFα, and LPL genes. We considered it particularly important to investigate the relationship of gene polymorphisms involved in chronic inflammation with the risk of T2DM or uncontrolled biochemical parameters.

METHODS

We included 199 individuals with a T2DM diagnosis and 213 individuals without a T2DM diagnosis. Restriction fragment length polymorphism (RFLP) analyses were used to assess polymorphisms.

RESULTS

We found a risk association between T2DM and uncontrolled biochemical parameters in a Mexican population for the genotypes del/del of NFκβ, -174 and -572 of IL-6, C/C of IL-1β, -308 and -238 of TNFα, and T/T of LPL. In subjects without diabetes (controls), we found an association between the G/C genotype of the -572 polymorphism and the G/C and C/C genotypes of the -597 polymorphism of IL-6 with the risk of glucose levels > 131 mg/dL. Genotype C/C of polymorphism -174 of the IL-6 gene was associated with high triglyceride levels, and levels > 5.8% of HbA1c were associated with the G/A genotype of TNFα -308.

CONCLUSION

Here, we describe for the first time the relationship of T2DM risk and uncontrolled biochemical parameters with polymorphisms in the NFκβ, IL-6, TNFα, IL-1β, and LPL genes in a Mexican population. We also showed that for the population included in this study, there is an additive effect of the polymorphisms of the studied genes that considerably increases the risk of developing T2DM.We also showed that there are interactions between genes related to chronic inflammation that affect the risk of T2DM.

Association of Metabolic Syndrome with Aerobic Exercise and LPL rs3779788 Polymorphism in Taiwan Biobank Individuals

PURPOSE

The Lipoprotein lipase (LPL) gene is a significant contributor to dyslipidemia. It has shown associations with several conditions including atherosclerosis, obesity, and metabolic syndrome (MetS). We assessed the interactive association between MetS and rs3779788 of the LPL gene based on aerobic exercise.

MATERIALS AND METHODS

Data were available for 7532 Taiwan Biobank (TWB) participants recruited between 2008 and 2016. We used multiple logistic regression to determine the odds ratios (OR) for MetS and their 95% confident intervals (C.I.). Potential variables included LPL rs3779788, aerobic exercise, sex, age, education, marital status, body mass index (BMI), smoking, alcohol consumption, midnight snacking, vegetarian diet, coffee, dietary fat, and tea drinking.

RESULTS

Aerobic exercise was protective against MetS (OR, 0.858; 95% C.I., 0.743-0.991). Compared to CC/CT genotype, the OR for developing MetS was 0.875, (95% C.I., 0.571-1.341) in TT individuals. The test for interaction was significant for the rs3779788 variant and aerobic exercise (p = 0.0484). In our group analyses, the OR for MetS was 0.841 (95% C.I., 0.727-0.974) in CC/CT and 4.076 (95% C.I., 1.158-14.346) in TT individuals who did aerobic exercise compared to those who did not.

CONCLUSION

Our study indicated that aerobic exercise improved metabolic syndrome in Taiwanese adults with rs3779788 CC/CT genotype relative to those with TT genotype.

Gender-related relation between metabolic syndrome and S447X and HindIII polymorphisms of lipoprotein lipase gene in northern Iran

BACKGROUND

Metabolic syndrome is a cluster of conditions that increase risk of cardiovascular morbidity and mortality. Among genetic factors that contributed to incidence of metabolic syndrome, Polymorphisms of Lipoprotein lipase (LPL) are major candidates especially because of their effect on obesity and dyslipidemia. S447X (rs328) and Hind III (rs320) Polymorphisms of LPL gene have been reported to change LPL activity, resulting in altered triglyceride (TG) and high density lipoprotein Cholesterol (HDL-C) levels. This study investigates the effects of these gene polymorphisms on factors affecting metabolic syndrome in northern population of Iran.

METHODS

Studied population included 223 adults consisting 90 women and 133 men with body mass index (BMI) ≥ 30 kg/m² as obese subjects, and 156 healthy participants as a control group with BMI <25 that included 68 women and 88 men. All factors causing metabolic syndrome were evaluated. Also DNA was extracted from blood samples and HindIII and S447X LPL gene polymorphisms were screened by polymerase chain reaction-restriction fragment length polymorphism method (PCR-RFLP).

CONCLUSIONS

The present study proves that some genotypes of S447X were associated with a reduced risk of developing low HDL-C only in men, while the protective effects of HindIII on hypertriglyceridemia were only seen in women [corrected]. The point is that this relation is affected by the weight profile of the participants. It can be concluded that there is a gender-related relation between the polymorphisms of LPL gene and the risk factors for incidence of metabolic syndrome in the northern population of Iran.

The Association of a Rare Variant of -93, -53 Promoter Gene Polymorphisms of Lipoprotein Lipase gene with Obesity and Insulin Resistance

Objectives

Obesity increases the risk of numerous chronic diseases. Obesity is classified clinically using body mass index (BMI), waist-to-hip ratio, and body fat percentage. The lipoprotein lipase (LPL) gene has been linked to lipoprotein metabolism and obesity. We performed a case-control study to determine the association between LPL gene polymorphisms and obesity-associated phenotypes such as insulin resistance (IR).

Methods

We examined the different LPL gene variants for association in 642 individuals segregated by BMI and IR. Genotyping of the LPL gene -93 and -53 promoter gene polymorphisms were analyzed using polymerase chain reaction-restriction fragment length polymorphism.

Results

A substantial association was observed for -93 gene polymorphism of the LPL gene with obesity, while -53 promoter gene polymorphism showed association with IR.

Conclusions

We found a significant association between -93 and -53 promoter gene polymorphisms of the LPL gene with obesity and associated phenotypes in the studied population.

High fat diet modifies the association of lipoprotein lipase gene polymorphism with high density lipoprotein cholesterol in an Asian Indian population

Background

Single nucleotide polymorphisms (SNPs) in lipoprotein lipase gene (LPL) have been shown to influence metabolism related to lipid phenotypes. Dietary factors have been shown to modify the association between LPL SNPs and lipids; however, to date, there are no studies in South Asians. Hence, we tested for the association of four common LPL SNPs with plasma lipids and examined the interactions between the SNPs and dietary factors on lipids in 1,845 Asian Indians.

Methods

The analysis was performed in 788 Type 2 diabetes cases and 1,057 controls randomly chosen from the cross-sectional Chennai Urban Rural Epidemiological Study. Serum triacylglycerol (TAG), serum total cholesterol, and high-density lipoprotein cholesterol (HDL-C) were measured using a Hitachi-912 autoanalyzer (Roche Diagnostics GmbH, Mannheim, Germany). Dietary intake was assessed using a semi-quantitative food frequency questionnaire. The SNPs (rs1121923, rs328, rs4922115 and rs285) were genotyped by polymerase chain reaction followed by restriction enzyme digestion and 20% of samples were sequenced to validate the genotypes obtained. Statistical Package for Social Sciences for Windows version 22.0 (SPSS, Chicago, IL) was used for statistical analysis.

Results

After correction for multiple testing and adjusting for potential confounders, SNPs rs328 and rs285 showed association with HDL-C (P = 0.0004) and serum TAG (P = 1×10⁻⁵), respectively. The interaction between SNP rs1121923 and fat intake (energy %) on HDL-C (P = 0.003) was also significant, where, among those who consumed a high fat diet (28.4 ± 2.5%), the T allele carriers (TT + XT) had significantly higher HDL-C concentrations (P = 0.0002) and 30% reduced risk of low HDL-C levels compared to the CC homozygotes. None of the interactions on other lipid traits were statistically significant.

Conclusion

Our findings suggest that individuals carrying T allele of the SNP rs1121923 have increased HDL-C levels when consuming a high fat diet compared to CC homozygotes. Our finding warrants confirmation in prospective studies and randomized controlled trials.

Electronic supplementary material

The online version of this article (doi:10.1186/s12986-016-0155-1) contains supplementary material, which is available to authorized users.

Adipocyte ATP-binding cassette G1 promotes triglyceride storage, fat mass growth, and human obesity

The role of the ATP-binding cassette G1 (ABCG1) transporter in human pathophysiology is still largely unknown. Indeed, beyond its role in mediating free cholesterol efflux to HDL, the ABCG1 transporter equally promotes lipid accumulation in a triglyceride (TG)-rich environment through regulation of the bioavailability of lipoprotein lipase (LPL). Because both ABCG1 and LPL are expressed in adipose tissue, we hypothesized that ABCG1 is implicated in adipocyte TG storage and therefore could be a major actor in adipose tissue fat accumulation. Silencing of Abcg1 expression by RNA interference in 3T3-L1 preadipocytes compromised LPL-dependent TG accumulation during the initial phase of differentiation. Generation of stable Abcg1 knockdown 3T3-L1 adipocytes revealed that Abcg1 deficiency reduces TG storage and diminishes lipid droplet size through inhibition of Pparγ expression. Strikingly, local inhibition of adipocyte Abcg1 in adipose tissue from mice fed a high-fat diet led to a rapid decrease of adiposity and weight gain. Analysis of two frequent ABCG1 single nucleotide polymorphisms (rs1893590 [A/C] and rs1378577 [T/G]) in morbidly obese individuals indicated that elevated ABCG1 expression in adipose tissue was associated with increased PPARγ expression and adiposity concomitant to increased fat mass and BMI (haplotype AT>GC). The critical role of ABCG1 in obesity was further confirmed in independent populations of severe obese and diabetic obese individuals. This study identifies for the first time a major role of adipocyte ABCG1 in adiposity and fat mass growth and suggests that adipose ABCG1 might represent a potential therapeutic target in obesity.

The -93T/G LPL Promoter Polymorphism Is Associated With Lower Third-Trimester Triglycerides in Pregnant African American Women

BACKGROUND

Hypertriglyceridemia is a risk factor for cardiovascular disease and several pregnancy complications. Lipoprotein lipase (LPL) genetic variation modulates nonpregnancy plasma triglycerides, but its effects during pregnancy are unknown. The G allele of the LPL -93T/G promoter polymorphism is 16-23 times more prevalent in Blacks than in Whites, contributing to lower triglycerides in nonpregnant African Americans by increasing LPL expression.

PURPOSE

This study investigated whether the triglyceride-lowering effect of -93G is observed in African Americans during pregnancy.

METHODS

Genotyping was performed on 124 African American women with uncomplicated pregnancies for common functional LPL polymorphisms/mutations (-93T/G, D9N, N291S, and S447X). Third-trimester plasma triglyceride, high- and low-density lipoprotein cholesterol, apolipoprotein B, and free fatty acid concentrations were measured with colorimetric assays. Clinical characteristics and lipid values were compared across the -93T/G genotypes.

RESULTS

Triglycerides were significantly lower in women with the -93GG compared to the -93TT genotype, both with (n = 124, p = .02) and without (n = 108, p = .03) inclusion of participants with other LPL variant alleles. Triglyceride differences persisted after adjustment for prepregnancy body mass index, gestational age at delivery, and smoking. There were no significant differences in the other lipids or apolipoprotein B by -93T/G genotype.

CONCLUSIONS

Despite the considerable metabolic changes accompanying pregnancy, the triglyceride-lowering effect associated with the -93GG LPL genotype in African Americans persists during late pregnancy. The -93GG genotype might protect against pregnancy complications stemming from hypertriglyceridemia, but the overall increased risk of pregnancy complications in African American women points to complex, multifactorial relationships among risk factors, race, and adverse pregnancy outcomes.

Diabetes and associated complications in the South Asian population

The rising prevalence of diabetes in South Asians has significant health and economic implications. South Asians are predisposed to the development of diabetes due to biologic causes which are exacerbated by lifestyle and environmental factors. Furthermore, they experience significant morbidity and mortality from complications of diabetes, most notably coronary artery disease, cerebrovascular disease, and chronic kidney disease. Therefore, understanding the pathophysiology and genetics of diabetes risk factors and its associated complications in South Asians is paramount to curbing the diabetes epidemic. With this understanding, the appropriate screening, preventative and therapeutic strategies can be implemented and further developed. In this review, we discuss in detail the biologic and lifestyle factors that predispose South Asians to diabetes and review the epidemiology and pathophysiology of microvascular and macrovascular complications of diabetes in South Asians. We also review the ongoing and completed diabetes prevention and management studies in South Asians.

Adipose tissue changes in obesity and the impact on metabolic function

Obesity is associated with adverse alterations in adipose tissue that predispose to metabolic dysregulation. These adverse alterations include accumulation of inflammatory macrophages leading to the activation of inflammation pathways, reduction in lipid turnover, and deposition of fat in ectopic locations. These alterations are precursors to the development of insulin resistance and metabolic dysfunction.

Global O-GlcNAc Levels Modulate Transcription of the Adipocyte Secretome during Chronic Insulin Resistance

Increased flux through the hexosamine biosynthetic pathway and the corresponding increase in intracellular glycosylation of proteins via O-linked β-N-acetylglucosamine (O-GlcNAc) is sufficient to induce insulin resistance (IR) in multiple systems. Previously, our group used shotgun proteomics to identify multiple rodent adipocytokines and secreted proteins whose levels are modulated upon the induction of IR by indirectly and directly modulating O-GlcNAc levels. We have validated the relative levels of several of these factors using immunoblotting. Since adipocytokines levels are regulated primarily at the level of transcription and O-GlcNAc alters the function of many transcription factors, we hypothesized that elevated O-GlcNAc levels on key transcription factors are modulating secreted protein expression. Here, we show that upon the elevation of O-GlcNAc levels and the induction of IR in mature 3T3-F442a adipocytes, the transcript levels of multiple secreted proteins reflect the modulation observed at the protein level. We validate the transcript levels in male mouse models of diabetes. Using inguinal fat pads from the severely IR db/db mouse model and the mildly IR diet-induced mouse model, we have confirmed that the secreted proteins regulated by O-GlcNAc modulation in cell culture are likewise modulated in the whole animal upon a shift to IR. By comparing the promoters of similarly regulated genes, we determine that Sp1 is a common cis-acting element. Furthermore, we show that the LPL and SPARC promoters are enriched for Sp1 and O-GlcNAc modified proteins during insulin resistance in adipocytes. Thus, the O-GlcNAc modification of proteins bound to promoters, including Sp1, is linked to adipocytokine transcription during insulin resistance.

Genetic determinants of glucose homeostasis

Type 2 diabetes is a complex metabolic disorder characterised by varying degrees of impairment in insulin secretion and resistance to the action of insulin. Considerable progress has been made recently in understanding the genetic determinants of diabetes. A logical next step is to describe how these variants relate to the underlying pathophysiological processes that lead to diabetes as this may provide insights into pathways to disease. These quantitative traits are, of course, of direct interest in themselves and a growing literature is now emerging on the genetic determinants of insulin secretion and insulin resistance. This review article focuses on describing the complex associations between type 2 diabetes risk variants and quantitative glycaemic traits and the relationship between variants initially discovered in association studies of these traits and risk of type 2 diabetes.

Prevalence, risk factors and complications associated with type 2 diabetes in migrant South Asians

It is estimated that type 2 diabetes (T2D) currently affects about 246 million people worldwide, with South Asians, especially Indians, having both the largest number of cases and the fastest growing prevalence. South Asian ethnicity has been identified as a major risk factor for the development of T2D with central adiposity, insulin resistance and an unfavourable lipid profile being identified as predominant signals of alarm. Leading databases, including Web of Science, Medline, PubMed and Science Direct, were consulted and manual searches were conducted for cited references in leading diabetes-related journals. In all, 152 articles were included for the final assessment reported in this review. Genetic predisposition, central adiposity and unfavourable lifestyle, including physical inactivity and an unhealthy diet, were associated with the prevalence of T2D in migrant South Asians. 'Westernization', acculturation, socio-economic factors and lack of knowledge about the disease have also been identified as contributors to the development of T2D in this population. Higher prevalence of T2D in migrant South Asians may not be entirely attributed to genetic predisposition; hence, ethnicity and associated modifiable risk factors need further investigation. Preventive measures and appropriate interventions are currently limited by the lack of ethnic-specific cut-off points for anthropometric and biological markers, as well as by the absence of reliable methods for dietary and physical activity assessment. This article describes the prevalence rate, risk factors and complications associated with T2D in migrant South Asians living in different countries.

The HindIII polymorphism in the lipoprotein lipase gene predicts type 2 diabetes risk among Chinese adults

OBJECTIVE

We aimed to investigate the polymorphism HindIII of the lipoprotein lipase (LPL) gene to explore whether it had a potential role in susceptibility to type 2 diabetes mellitus (T2DM) among Han Chinese, and whether this effect was influenced by regulating LPL or other risk factors.

METHODS

Overall, 654 Han Chinese adults were selected from a community-based cross-sectional study using a stratified cluster random sampling. Genotyping was performed using the PCR-RFLP technique, and the metabolic variables were measured using standard methods.

RESULTS

Individuals with the HindIII H-/H- genotype tended to have higher pre-heparin LPL (PrLPL) and lower triglyceride levels but an unexpected higher prevalence of T2DM compared with the H+/H+ genotype carriers. The association between the H-/H- genotype and T2DM risk remained unchanged across all subgroups of lipids/glucose-related RF. In a recessive model, the H-/H- genotype conferred a 2.12-fold increased risk [odds ratio (OR): 3.12; 95% confidence interval (CI): 1.18-8.27] for T2DM after controlling for age and sex, and increased further after additionally adjusting for traditional RFs, and PrLPL (OR=4.45; 95% CI=1.51-13.07).

CONCLUSIONS

This study indicated that Chinese adults with the LPL gene HindIII H-/H- genotype had a significantly increased risk of T2DM, even if they had favorable lipid profiles.

Comparative studies of vertebrate lipoprotein lipase: a key enzyme of very low density lipoprotein metabolism

Lipoprotein lipase (LIPL or LPL; E.C.3.1.1.34) serves a dual function as a triglyceride lipase of circulating chylomicrons and very-low-density lipoproteins (VLDL) and facilitates receptor-mediated lipoprotein uptake into heart, muscle and adipose tissue. Comparative LPL amino acid sequences and protein structures and LPL gene locations were examined using data from several vertebrate genome projects. Mammalian LPL genes usually contained 9 coding exons on the positive strand. Vertebrate LPL sequences shared 58-99% identity as compared with 33-49% sequence identities with other vascular triglyceride lipases, hepatic lipase (HL) and endothelial lipase (EL). Two human LPL N-glycosylation sites were conserved among seven predicted sites for the vertebrate LPL sequences examined. Sequence alignments, key amino acid residues and conserved predicted secondary and tertiary structures were also studied. A CpG island was identified within the 5'-untranslated region of the human LPL gene which may contribute to the higher than average (×4.5 times) level of expression reported. Phylogenetic analyses examined the relationships and potential evolutionary origins of vertebrate lipase genes, LPL, LIPG (encoding EL) and LIPC (encoding HL) which suggested that these have been derived from gene duplication events of an ancestral neutral lipase gene, prior to the appearance of fish during vertebrate evolution. Comparative divergence rates for these vertebrate sequences indicated that LPL is evolving more slowly (2-3 times) than for LIPC and LIPG genes and proteins.

Evaluation of single nucleotide polymorphisms of Pro12Ala in peroxisome proliferator-activated receptor-γ and Gly308Ala in tumor necrosis factor-α genes in obese Asian Indians: a population-based study

BACKGROUND

A population-based case control study was performed to determine the associations of Pro12Ala polymorphism in peroxisome proliferator-activated receptor-γ (PPARG) and Gly308Ala polymorphism in tumor necrosis factor-α (TNFA) genes in obese subjects.

PATIENTS AND METHODS

Of 1,400 eligible subjects, ≧20 years, we recruited only 1,127. For extreme phenotype case-control design, we evaluated 201 subjects with body mass index (BMI) ≧30 kg/m(2) (Group 1) and 143 with BMI <20 kg/m(2) (Group 2). Clinical, anthropometric, biochemical, and nutritional details and polymorphisms were estimated.

RESULTS

In Group 1, the dietary intake of calories and fats was higher, physical activity was lower, and prevalence of truncal obesity, hypertension, high total cholesterol, low high-density lipoprotein cholesterol, and diabetes was greater than in Group 2. There were no homozygous polymorphisms of either gene. Heterozygous Pro12Ala polymorphism in PPARG was found in 15 (7.5%) subjects in Group 1 and 3 (2.1%) subjects in Group 2 (P = 0.028), and heterozygous Gly308Ala polymorphism in TNFA was found in 19 (9.5%) in Group 1 and 7 (4.9%) in Group 2 (P = 0.115). Presence of heterozygous polymorphism in PPARG and TNFA-predicted obesity with univariate odds ratio ([OR], 95% confidence intervals) of 2.25 (1.32-3.84, P = 0.003) and 1.48 (1.10-1.99, P = 0.009) and with multivariate OR 1.74 (1.03-2.93, P = 0.038) and 1.46 (1.05-2.03, P = 0.024), respectively. The addition of dietary and physical activity variables did not result in significant change.

CONCLUSION

Obese Asian Indians have greater prevalence of heterozygous polymorphisms of Pro12Ala in PPARG and Gly308Ala in TNFA genes.

Obesity management interventions: a review of the evidence

The burden of disease associated with the obesity epidemic shortens lives, and prevalence is accelerating. As with other chronic diseases, improved outcomes are associated with effective self-management of obesity across the life span. The disease of obesity, then, fits squarely within the disease management and chronic care models. This article reviews selected interventions, described in peer-reviewed literature, designed to achieve significant weight loss for individuals identified as overweight or obese. The study objective is to provide an overview of the full range of methods and models for weight loss, including some available without medical supervision. The intended audience includes individuals and organizations with an expressed interest in disease management and the chronic care models. Our review identified promising lines of investigation for future research that span diverse medical disciplines applied to obesity. The quality of the studies included in our review was uneven, and compromises the current evidence for effectiveness and efficacy. Generally, our results showed that combination approaches-surgical or pharmacologic, combined with a behavioral intervention-were most likely to be effective.

Apolipoprotein A5 and lipoprotein lipase interact to modulate anthropometric measures in Hispanics of Caribbean origin

Apolipoprotein A5 (APOA5) and lipoprotein lipase (LPL) proteins interact functionally to regulate lipid metabolism, and single-nucleotide polymorphisms (SNPs) for each gene have also been associated independently with obesity risk. Evaluating gene combinations may be more effective than single SNP analyses in identifying genetic risk, but insufficient minor allele frequency (MAF) often limits evaluations of potential epistatic relationships. Populations with multiple ancestral admixtures may provide unique opportunities for evaluating genetic interactions. We examined relationships between LPL m107 (rs1800590) and APOA5 S19W (rs3135506) and lipid and anthropometric measures in Caribbean origin Hispanics (n = 1,019, aged 45-75 years) living in the Boston metropolitan area. Significant interaction terms between LPL m107 and APOA5 S19W were observed for BMI (P = 0.003) and waist circumference (P = 0.019). Higher BMI (P = 0.001), waist (P = 0.011) and hip (P = 0.026) circumference were observed in minor allele (G) carriers for LPL m107 who also carried the APOA5 S19W minor allele (G). Additionally, extreme obesity (BMI > or = 40 kg/m(2)) risk was higher (odds ratio = 4.02; 95% confidence interval: 1.81-8.91; global P = 0.008) for minor allele carriers for both SNPs (LPL TG+GG, APOA5 CG+GG) compared to major allele carriers for both SNPs. In summary, we identified significant interactions for APOA5 S19W and LPL m107 for obesity in Caribbean Hispanics. Population-specific MAFs increase the difficulties of replicating gene-gene interactions, but may support the hypothesis that combinations of frequencies in selected genes could heighten obesity susceptibility in a given population. Analyses of gene-gene interactions may improve understanding of genetically based obesity risk, and underscore the need for further study of groups with multiple ancestral admixtures.

Heritability of quantitative traits associated with type 2 diabetes mellitus in large multiplex families from South India

India is a major contributor to the global public health burden of diabetes. We have undertaken a family study of large multiplex families from Chennai, South India, and report on the familial aggregation of quantitative traits associated with type 2 diabetes mellitus in these pedigrees. Five hundred twenty-four individuals older than 19 years from 26 large multiplex pedigrees were ascertained. Detailed questionnaires and phenotype data were obtained on all participating individuals including fasting blood glucose, fasting insulin, lipid profiles, height, weight, and other anthropometric and clinical measures. Heritability estimates were calculated for all quantitative traits at the univariate level, and bivariate analyses were done to determine the correlation in genetic and environmental control across these quantitative traits. Heritability estimates ranged from 0.21 to 0.72. The heritability estimates for traits most directly related to type 2 diabetes mellitus were 0.24 +/- 0.08 for fasting blood glucose and 0.41 +/- 0.09 for fasting insulin. In addition, there was evidence for common genetic control for many pairs of these traits. These bivariate analyses suggested common genes for fasting insulin and central obesity measures (body mass index, waist, and hip), with complete genetic correlation between fasting insulin and waist. Quantitative traits associated with type 2 diabetes mellitus have heritabilities suggestive of some familial or genetic effect. The evidence for pleiotropic control of insulin and central obesity-related traits supports the presence of an insulin resistance syndrome in South Asians with a tendency for central obesity.

Lipoprotein lipase: from gene to obesity

Lipoprotein lipase (LPL) is a multifunctional enzyme produced by many tissues, including adipose tissue, cardiac and skeletal muscle, islets, and macrophages. LPL is the rate-limiting enzyme for the hydrolysis of the triglyceride (TG) core of circulating TG-rich lipoproteins, chylomicrons, and very low-density lipoproteins (VLDL). LPL-catalyzed reaction products, fatty acids, and monoacylglycerol are in part taken up by the tissues locally and processed differentially; e.g., they are stored as neutral lipids in adipose tissue, oxidized, or stored in skeletal and cardiac muscle or as cholesteryl ester and TG in macrophages. LPL is regulated at transcriptional, posttranscriptional, and posttranslational levels in a tissue-specific manner. Nutrient states and hormonal levels all have divergent effects on the regulation of LPL, and a variety of proteins that interact with LPL to regulate its tissue-specific activity have also been identified. To examine this divergent regulation further, transgenic and knockout murine models of tissue-specific LPL expression have been developed. Mice with overexpression of LPL in skeletal muscle accumulate TG in muscle, develop insulin resistance, are protected from excessive weight gain, and increase their metabolic rate in the cold. Mice with LPL deletion in skeletal muscle have reduced TG accumulation and increased insulin action on glucose transport in muscle. Ultimately, this leads to increased lipid partitioning to other tissues, insulin resistance, and obesity. Mice with LPL deletion in the heart develop hypertriglyceridemia and cardiac dysfunction. The fact that the heart depends increasingly on glucose implies that free fatty acids are not a sufficient fuel for optimal cardiac function. Overall, LPL is a fascinating enzyme that contributes in a pronounced way to normal lipoprotein metabolism, tissue-specific substrate delivery and utilization, and the many aspects of obesity and other metabolic disorders that relate to energy balance, insulin action, and body weight regulation.

Mechanisms of lipase maturation

Lipases are acyl hydrolases that represent a diverse group of enzymes present in organisms ranging from prokaryotes to humans. This article focuses on an evolutionarily related family of extracellular lipases that include lipoprotein lipase, hepatic lipase and endothelial lipase. As newly synthesized proteins, these lipases undergo a series of co- and post-translational maturation steps occurring in the endoplasmic reticulum, including glycosylation and glycan processing, and protein folding and subunit assembly. This article identifies and discusses mechanisms that direct early and late events in lipase folding and assembly. Lipase maturation employs the two general chaperone systems operating in the endoplasmic reticulum, as well as a recently identified lipase-specific chaperone termed lipase maturation factor 1. We propose that the two general chaperone systems act in a coordinated manner early in lipase maturation in order to help create partially folded monomers; lipase maturation factor 1 then facilitates final monomer folding and subunit assembly into fully functional homodimers. Once maturation is complete, the lipases exit the endoplasmic reticulum and are secreted to extracellular sites, where they carry out a number of functions related to lipoprotein and lipid metabolism.

Association of lipoprotein lipase (LPL) single nucleotide polymorphisms with type 2 diabetes mellitus

The etiology and pathogenesis of type 2 diabetes mellitus (T2DM) are not completely understood although it is often associated with other conditions such as obesity, hypertension, and dyslipidemia. Lipoprotein lipase (LPL) is a key enzyme in human lipid metabolism that facilitates the removal of triglyceride-rich lipoproteins from the bloodstream. LPL hydrolyzes the core of triglyceride-rich lipoproteins (chylomicrons and very low density lipoprotein) into free fatty acids and monoacylglycerol. To gain insight into the possible role of LPL in T2DM, nine single nucleotide polymorphisms (SNPs) of LPL were analyzed for the association with T2DM using 944 unrelated Koreans, including 474 T2DM subjects and 470 normal healthy controls. Of the nine LPL SNPs we analyzed, a significant association with multiple tests by the false discovery rate (FDR) was observed between T2DM and SNP rs343 (+13836C>A in intron 3). SNP rs343 was also marginally associated with some of T2DM-related phenotypes including total cholesterol, high density lipoprotein cholesterol (HDLc), and log transformed glycosylated hemoglobin in 470 normal controls, although no significant association was detected by multiple tests. In total, our results suggest that the control of lipid level by LPL in the bloodstream might be an important factor in T2DM pathogenesis in the Korean population.