Association of the TRIB1 tribbles homolog 1 gene rs17321515 A>G polymorphism and serum lipid levels in the Mulao and Han populations

TRIB1 regulates LDL metabolism through CEBPα-mediated effects on the LDL receptor in hepatocytes

Genetic variants near the TRIB1 gene are highly significantly associated with plasma lipid traits and coronary artery disease. While TRIB1 is likely causal of these associations, the molecular mechanisms are not well understood. Here we sought to investigate how TRIB1 influences low density lipoprotein cholesterol (LDL-C) levels in mice. Hepatocyte-specific deletion of Trib1 (Trib1Δhep) in mice increased plasma cholesterol and apoB and slowed the catabolism of LDL-apoB due to decreased levels of LDL receptor (LDLR) mRNA and protein. Simultaneous deletion of the transcription factor CCAAT/enhancer-binding protein alpha (CEBPα) with TRIB1 eliminated the effects of TRIB1 on hepatic LDLR regulation and LDL catabolism. Using RNA-seq, we found that activating transcription factor 3 (Atf3) was highly upregulated in the livers of Trib1Δhep but not Trib1Δhep CebpaΔhep mice. ATF3 has been shown to directly bind to the CEBPα protein, and to repress the expression of LDLR by binding its promoter. Blunting the increase of ATF3 in Trib1Δhep mice reduced the levels of plasma cholesterol and partially attenuated the effects on LDLR. Based on these data, we conclude that deletion of Trib1 leads to a posttranslational increase in CEBPα, which increases ATF3 levels, thereby contributing to the downregulation of LDLR and increased plasma LDL-C.

Interaction between Coffee Drinking and TRIB1 rs17321515 Single Nucleotide Polymorphism on Coronary Heart Disease in a Taiwanese Population

A complex interplay of several genetic and lifestyle factors influence coronary heart disease (CHD). We determined the interaction between coffee consumption and the tribbles pseudokinase 1 (TRIB1) rs17321515 variant on coronary heart disease (CHD). Data on CHD were obtained from the National Health Insurance Research Database (NHIRD) while genotype data were collected from the Taiwan Biobank (TWB) Database. From the linked electronic health record data, 1116 individuals were identified with CHD while 7853 were control individuals. Coffee consumption was associated with a lower risk of CHD. The multivariate-adjusted odds ratio (OR) and 95% confidence interval (CI) was 0.84 (0.72-0.99). Association of CHD with the TRIB1 rs17321515 variant was not significant. The OR (95% CI) was 1.01 (0.72-0.99). There was an interaction between TRIB1 rs17321515 and coffee consumption on CHD risk (p for interaction = 0.0330). After stratification by rs17321515 genotypes, coffee drinking remained significantly associated with a lower risk of CHD only among participants with GG genotype (OR, 0.62; 95% CI, 0.45-0.85). In conclusion, consumption of coffee was significantly associated with a decreased risk of CHD among Taiwanese adults with the TRIB1 GG genotype.

Associations for BCO2, PCSK9, and TR1B1 Polymorphism and Lifestyle Factors with Ischemic Stroke: A Nested Case-Control Study

PURPOSE

To investigate associations for polymorphisms in β-carotene 9',10'-oxygenase (BCO2, rs10431036 and rs11214109), proprotein convertase subtilisin kexin type 9 (PCSK9, rs11583680), and tribbles pseudokinase 1 (TRIB1, rs17321515 and rs2954029), as well as lifestyle factors, with ischemic stroke (IS).

MATERIALS AND METHODS

This nested case-control study included 161 patients with IS and 483 matched control individuals. We collected medical reports, lifestyle details, and blood samples from individuals and used the PCR-ligase detection reaction method to genotype single nucleotide polymorphisms (SNPs).

RESULTS

The GA+AA genotype of rs10431036 (p<0.001) and rs17321515 (p=0.003), the CT+TT genotype of rs11214109 (p=0.005), and the TA+AA genotype of rs2954029 (p=0.006) in dominant models increased the risk of IS. In additive models, the GG genotype of rs17321515 (p=0.005) and the TT genotype of rs2954029 (p=0.008) increased the risk of IS. Adequate intake of fruits/vegetables reduced the risk of IS (p=0.005). Although there was no interaction between genes and fruits/vegetables, people with inadequate intake of fruits/vegetables who carried a risk genotype had a higher risk of IS than those only having inadequate fruits/vegetables intake or those only carrying a risk genotype. Also, the haplotypes AC, AT, and GT (comprising rs10431036 and rs11214109) and GT (comprising rs2954029 and rs17321515) were found to be associated with an increased risk of IS (p<0.05).

CONCLUSION

Polymorphisms in BCO2 and TRIB1 and fruits/vegetables intake were associated with IS. These results provide the theoretical basis for gene screening to prevent chronic cerebrovascular diseases.

RAD51B (rs8017304 and rs2588809), TRIB1 (rs6987702, rs4351379, and rs4351376), COL8A1 (rs13095226), and COL10A1 (rs1064583) Gene Variants with Predisposition to Age-Related Macular Degeneration

Background

Age-related macular degeneration (AMD) is a progressive neurodegenerative disease of a central part of the neural retina (macula) and a leading cause of blindness in elderly people. While it is known that the AMD is a multifactorial disease, genetic factors involved in lipid metabolism, inflammation, and neovascularization are currently being widely studied in genome-wide association studies (GWAS). The aim of our study was to evaluate the impact of new single nucleotide polymorphisms (SNPs) in RAD51B, TRIB1, COL8A1, and COL10A1 genes on AMD development.

Methods

Case-control study involved 254 patients diagnosed with early AMD, 244 patients with exudative AMD, and 942 control subjects. The genotyping of RAD51B (rs8017304 and rs2588809), TRIB1 (rs6987702, rs4351379, and rs4351376), COL8A1 (rs13095226), and COL10A1 (rs1064583) was carried out using TaqMan assays by a real-time polymerase chain reaction (RT-PCR) method.

Results

Statistically significant difference was found in genotype (TT, TC, and CC) distribution of COL8A1 rs13095226 between exudative AMD and control groups (60.2%, 33.6%, and 6.1% vs. 64.9%, 32.3%, and 2.9%, respectively, p = 0.036). Also, comparing with TT+TC, rs13095226 CC genotype was associated with 3.5-fold increased odds of exudative AMD development (OR = 3.540; 95% CI: 1.415-8.856; p = 0.007).

Conclusion

Our study revealed a strong association between a variant in COL8A1 (rs13095226) and exudative AMD development.

Novel tricyclic glycal-based TRIB1 inducers that reprogram LDL metabolism in hepatic cells

Increased expression of the Tribbles pseudokinase 1 gene (TRIB1) is associated with lower plasma levels of LDL cholesterol and triglycerides, higher levels of HDL cholesterol and decreased risk of coronary artery disease and myocardial infarction. We identified a class of tricyclic glycal core-based compounds that upregulate TRIB1 expression in human HepG2 cells and phenocopy the effects of genetic TRIB1 overexpression as they inhibit expression of triglyceride synthesis genes and ApoB secretion in cells. In addition to predicted effects related to downregulation of VLDL assembly and secretion these compounds also have unexpected effects as they upregulate expression of LDLR and stimulate LDL uptake. This activity profile is unique and favorably differs from profiles produced by statins or other lipoprotein targeting therapies. BRD8518, the initial lead compound from the tricyclic glycal class, exhibited stereochemically dependent activity and the potency far exceeding previously described benzofuran BRD0418. Gene expression profiling of cells treated with BRD8518 demonstrated the anticipated changes in lipid metabolic genes and revealed a broad stimulation of early response genes. Consistently, we found that BRD8518 activity is MEK1/2 dependent and the treatment of HepG2 cells with BRD8518 stimulates ERK1/2 phosphorylation. In agreement with down-regulation of genes controlling triglyceride synthesis and assembly of lipoprotein particles, the mass spectrometry analysis of cell extracts showed reduced rate of incorporation of stable isotope labeled glycerol into triglycerides in BRD8518 treated cells. Furthermore, we describe medicinal chemistry efforts that led to identification of BRD8518 analogs with enhanced potency and pharmacokinetic properties suitable for in vivo studies.

Association of RBM5 rs2013208 SNP with serum lipid levels in two Chinese ethnic groups

The RNA binding motif protein 5 gene (RBM5) rs2013208 single nucleotide polymorphism (SNP) has been associated with high-density lipoprotein cholesterol (HDL-C) levels in a previous genome-wide association study, but little is known about such association of the RBM5 rs2013208 SNP and serum lipid profiles in the Chinese populations. The present study was to detect the association of the RBM5 rs2013208 SNP and several environmental factors with serum lipid levels in the Jing and Han populations. Genotyping of the RBM5 rs2013208 SNP in 635 subjects of Jing and 648 participants of Han peoples was performed by polymerase chain reaction and restriction fragment length polymorphism, and then confirmed by direct sequencing. There were no significant differences in the genotypic and allelic frequencies of the RBM5 rs2013208 SNP between the two ethnic groups or between males and females. The RBM5 rs2013208G allele carriers had lower serum HDL-C levels in both Jing and Han than the G allele non-carriers. The G allele carriers in Jing had higher serum total cholesterol (TC) levels and higher apolipoprotein (Apo) A1/ApoB ratio than the G allele non-carriers (P < 0.05). Subgroup analysis according to sex showed that the G allele carriers had lower serum HDL-C levels in both Jing and Han females but not in males (P < 0.05). The G allele carriers had higher TC levels in Jing females but not in Jing males, and lower ApoA1/ApoB ratio in Jing males but not in Jing females. Serum lipid parameters were also correlated with several environmental factors in the Jing and Han populations, or in males and females in both ethnic groups. The association of the RBM5 rs2013208 SNP and serum lipid levels is different between the Jing and Han populations. These associations might have an ethnic- and/or sex-specificity.

TRIB1 is a positive regulator of hepatocyte nuclear factor 4-alpha

The TRIB1 locus has been linked to both cardiovascular disease and hepatic steatosis. Recent efforts have revealed TRIB1 to be a major regulator of liver function, largely, but not exclusively, via CEBPA degradation. We recently uncovered a functional interaction between TRIB1 and HNF4A, another key regulator of hepatic function, whose molecular underpinnings remained to be clarified. Here we have extended these findings. In hepatoma models, HNF4A levels were found to depend on TRIB1, independently of its impact on CEBPA. Using a reporter assay model, MTTP reporter activity, which depends on HNF4A, positively correlated with TRIB1 levels. Confocal microscopy demonstrated partial colocalization of TRIB1 and HNF4A. Using overexpressed proteins we demonstrate that TRIB1 and HNF4A can form complexes in vivo. Mapping of the interaction interfaces identified two distinct regions within TRIB1 which associated with the N-terminal region of HNF4A. Lastly, the TRIB1-HNF4A interaction resisted competition with a CEPBA-derived peptide, suggesting different binding modalities. Together these findings establish that TRIB1 is required for HNF4A function. This regulatory axis represents a novel CEBPA-independent aspect of TRIB1 function predicted to play an important role in liver physiology.

Genetic determinants of inherited susceptibility to hypercholesterolemia - a comprehensive literature review

Hypercholesterolemia is a strong determinant of mortality and morbidity associated with cardiovascular diseases and a major contributor to the global disease burden. Mutations in four genes (LDLR, APOB, PCSK9 and LDLRAP1) account for the majority of cases with familial hypercholesterolemia. However, a substantial proportion of adults with hypercholesterolemia do not have a mutation in any of these four genes. This indicates the probability of having other genes with a causative or contributory role in the pathogenesis of hypercholesterolemia and suggests a polygenic inheritance of this condition. Here in, we review the recent evidence of association of the genetic variants with hypercholesterolemia and the three lipid traits; total cholesterol (TC), HDL-cholesterol (HDL-C) and LDL-cholesterol (LDL-C), their biological pathways and the associated pathogenetic mechanisms. Nearly 80 genes involved in lipid metabolism (encoding structural components of lipoproteins, lipoprotein receptors and related proteins, enzymes, lipid transporters, lipid transfer proteins, and activators or inhibitors of protein function and gene transcription) with single nucleotide variants (SNVs) that are recognized to be associated with hypercholesterolemia and serum lipid traits in genome-wide association studies and candidate gene studies were identified. In addition, genome-wide association studies in different populations have identified SNVs associated with TC, HDL-C and LDL-C in nearly 120 genes within or in the vicinity of the genes that are not known to be involved in lipid metabolism. Over 90% of the SNVs in both these groups are located outside the coding regions of the genes. These findings indicates that there might be a considerable number of unrecognized processes and mechanisms of lipid homeostasis, which when disrupted, would lead to hypercholesterolemia. Knowledge of these molecular pathways will enable the discovery of novel treatment and preventive methods as well as identify the biochemical and molecular markers for the risk prediction and early detection of this common, yet potentially debilitating condition.

Association of the ARL15 rs6450176 SNP and serum lipid levels in the Jing and Han populations

The association of ADP-ribosylation factor-like 15 (ARL15) rs6450176 single nucleotide polymorphism (SNP) and serum lipid profiles has never been studied in the Chinese population. The present study was undertaken to detect the association of ARL15 rs6450176 SNP and several environmental factors with serum lipid levels in the Jing and Han populations. Genotypes of the SNP were determined in 726 unrelated subjects of Jing nationality and 726 participants of Han nationality. The genotypic and allelic frequencies of the SNP in Jing but not in Han were different between males and females (P < 0.001 and P < 0.05; respectively). The G allele carriers in Han had lower serum total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C) and apolipoprotein (Apo) B levels, and higher ApoA1/ApoB ratio than the G allele non-carriers (P < 0.05-0.01). The G allele carriers in Jing had lower serum TC, high-density lipoprotein cholesterol (HDL-C), ApoA1, ApoB levels and higher ApoA1/ApoB ratio than the G allele non-carriers (P < 0.05 for all). Subgroup analyses showed that the G allele carriers had lower TC and LDL-C levels in Han males; lower LDL-C and ApoB levels in Han females; lower ApoB levels and ApoA1/ApoB ratio in Jing males; and lower LDL-C levels in Jing females than the G allele non-carriers (P < 0.05-0.01). Multiple linear regression analysis showed that serum TC, LDL-C, ApoB levels and the ApoA1/ApoB ratio in Han; and TC, HDL-C and ApoA1 levels in Jing were correlated with the genotypes of the ARL15 rs6450176 SNP (P < 0.05-0.001). Serum lipid parameters were also associated with several environmental factors in both ethnic groups. These findings indicated that there may be a racial/ethnic- and/or sex-specific association of the ARL15 rs6450176 SNP and serum lipid levels.

Association of the angiopoietin-like protein 8 rs2278426 polymorphism and several environmental factors with serum lipid levels

The present study was performed to examine the association of the angiopoietin-like protein 8 (ANGPTL8) rs2278426 single nucleotide polymorphism (SNP) and several environmental factors with serum lipid profiles in the Mulao and Han populations. A total of 879 individuals of the Mulao ethnic group and 865 individuals of the Han Chinese ethnic group were included. The serum apolipoprotein (Apo) B level was higher, however the serum ApoA1 level was lower in the Mulao individuals than in the Han individuals (P<0.05 and P<0.001, respectively). The genotypic and allelic frequencies, and the association with the ANGPTL8 rs2278426 SNP were different between the Mulao and Han populations. The frequency of the A allele was 17.80% in Han individuals and 23.04% in Mulao individuals (P<0.001). The frequencies of GG, GA and AA genotypes were 68.79, 26.82 and 4.39% in the Han population, and 60.64, 32.65 and 6.71% in the Mulao population (P<0.005), respectively. A significant association between the SNP and serum lipid traits was only detected in Han females and not in Han males or in the Mulao population. The subjects with GA/AA genotypes had lower low-density lipoprotein cholesterol (LDL-C) and ApoB levels, and higher ApoA1 levels with a higher ApoA1/ApoB ratio than the subjects with the GG genotype in the Han population. Subgroup analyses revealed that the subjects with the GA/AA genotype had lower levels of total cholesterol, LDL-C and ApoB, and a higher ApoA1/ApoB ratio than the subjects with the GG genotype in Han females (P<0.05-P<0.001). Serum lipid parameters were also associated with several environmental factors, including dietary patterns, lifestyle, obesity, physical inactivity and hypertension, in the two ethnic groups (P<0.05-0.001). These findings suggest that there may be an ethnic- and gender-specific association of the rs2278426 SNP and serum lipid parameters.

Association study of genetic variants at newly identified lipid gene TRIB1 with coronary heart disease in Chinese Han population

BACKGROUND

Recent genome-wide association studies (GWAS) have identified the variants near TRIB1 gene affecting blood lipid levels. However, the association between the reported variants and risk of coronary heart disease (CHD) was not confirmed.

METHODS

We conducted two independent case-control studies. The first study consisted of 300 CHD patients and 300 controls and the second study had 1,332 CHD patients and 2,811 controls. The genotypes of two variants rs3201475 and rs17321515 in TRIB1 were determined by TaqMan assay. The dual-luciferase reporter assay was performed for evaluating the function of the SNP rs3201475.

RESULTS

The statistical analysis indicated that single nucleotide polymorphism (SNP) rs17321515 was replicated to be associated with triglyceride (TG) level, which was also significantly associated with CHD risk when using the stratified analysis after adjusting for conventional risk factors. Compared with GG genotype, AA carriers of SNP rs17321515 had higher risk in males (odds ratio (OR)=1.28, 95%CI=1.01-1.61; P=0.03) and smokers (OR=1.41, 95%CI=1.09-1.88; P=0.01). We did not find significantly association between genotypes of rs3201475 and CHD risk. In addition, no significant difference was found in the luciferase activity assay of SNP rs3201475.

CONCLUSIONS

Our findings indicated that SNP rs17321515 is significantly associated with plasma TG level and the increasing risk of CHD among males and smokers in Chinese, whereas there is no positive association between SNP rs3201475 and CHD risk. Smoking could modify the effects of TRIB1 on CHD risk.

An epigenetic map of age-associated autosomal loci in northern European families at high risk for the metabolic syndrome

BACKGROUND

The prevalence of chronic diseases such as cancer, type 2 diabetes, metabolic syndrome (MetS), and cardiovascular disease increases with age in all populations. Epigenetic features are hypothesized to play important roles in the pathophysiology of age-associated diseases, but a map of these markers is lacking. We searched for genome-wide age-associated methylation signatures in peripheral blood of individuals at high risks for MetS by profiling 485,000 CpG sites in 192 individuals of Northern European ancestry using the Illumina HM450 array. Subjects (ages 6-85 years) were part of seven extended families, and 73% of adults and 32% of children were overweight or obese.

RESULTS

We found 22,122 genome-wide significant age-associated CpG sites (P α=0.05 = 3.65 × 10(-7) after correction for multiple testing) of which 14,155 are positively associated with age while 7,967 are negatively associated. By applying a positional density-based clustering algorithm, we generated a map of epigenetic 'hot-spots' of age-associated genomic segments, which include 290 age-associated differentially methylated CpG clusters (aDMCs), of which 207 are positively associated with age. Gene/pathway enrichment analyses were performed on these clusters using FatiGO. Genes localized to both the positively (n = 241) and negatively (n = 16) age-associated clusters are significantly enriched in specific KEGG pathways and GO terms. The most significantly enriched pathways are the hedgehog signaling pathway (adjusted P = 3.96 × 10(-3)) and maturity-onset diabetes of the young (MODY) (adjusted P = 6.26 × 10(-3)) in the positive aDMCs and type I diabetes mellitus (adjusted P = 3.69 × 10(-7)) in the negative aDMCs. We also identified several epigenetic loci whose age-associated change rates differ between subjects diagnosed with MetS and those without.

CONCLUSION

We conclude that in a family cohort at high risk for MetS, age-associated epigenetic features enrich in biological pathways important for determining the fate of fat cells and for insulin production. We also observe that several genes known to be related to MetS show differential epigenetic response to age in individuals with and without MetS.

Association of the ST3GAL4 rs11220462 polymorphism and serum lipid levels in the Mulao and Han populations

Background

A previous genome-wide association study has displayed the association of the ST3 beta-galactoside alpha-2,3-sialytransferase 4 (ST3GAL4) gene variant and lipid traits in the individuals of European ancestry, but the reproducibility of this association has not been detected in the Chinese population. The present study was undertaken to detect the association of ST3GAL4 rs11220462 single nucleotide polymorphism (SNP) and several environmental factors with serum lipid profiles in the Mulao and Han populations.

Methods

A total of 700 unrelated individuals of Mulao nationality and 694 subjects of Han nationality were randomly selected from our previous stratified randomized samples. Genotypes of the SNP were determined via polymerase chain reaction and restriction fragment length polymorphism in combination with gel electrophoresis, and then verified by direct sequencing.

Results

Serum apolipoprotein (Apo) B levels were higher and the ApoAI/ApoB ratio was lower in Mulao than in Han (P < 0.05-0.01). There were no significant differences in the genotypic and allelic frequencies of the ST3GAL4 rs11220462 SNP between the two ethnic groups or between males and females. The A allele carriers in both Mulao males and females had higher total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and ApoB levels than the A allele non-carriers (P < 0.05-0.01). The subjects with AA genotype in Han males but not in females had higher TC and triglyceride (TG) levels than the subjects with AG or GG genotype (P < 0.01 for each). Multiple linear regression analyses showed that the levels of TC, LDL-C and ApoB in Mulao females; TC and LDL-C in Mulao males; and TC in Han males were correlated with the genotypes (P < 0.05-0.001). Serum lipid parameters were also associated with several environmental factors in both ethnic groups (P < 0.05 -0.001).

Conclusions

The association of ST3GAL4 rs11220462 SNP and serum lipid levels was different between the Mulao and Han populations, suggesting that there may be a racial/ethnic-specific association, and/or sex-specific association between the ST3GAL4 rs11220462 SNP and serum lipid parameters in some ethnic groups.

Association between the MLX interacting protein-like, BUD13 homolog and zinc finger protein 259 gene polymorphisms and serum lipid levels

This study aimed to detect the association between the MLX interacting protein-like (MLXIPL), BUD13 homolog (BUD13) and zinc finger protein 259 (ZNF259) single nucleotide polymorphisms (SNPs) and serum lipid levels in the Chinese Mulao and Han populations. Genotyping of 9 SNPs was performed in 825 Mulao and 781 Han participants. The genotype and allele frequencies of ZNF259 rs2075290 and rs964184, and BUD13 rs10790162 SNPs were different between the Mulao and Han populations (P < 0.001). The SNPs of ZNF259 rs2075290 and BUD13 rs10790162 were associated with serum total cholesterol levels; ZNF259 rs2075290 and rs964184, BUD13 rs10790162, and MLXIPL rs3812316 and rs13235543 were associated with triglyceride (TG); and MLXIPL rs35332062 was associated with apolipoprotein (Apo) A1 in the Mulaos (P < 0.006–0.001). However, in the Hans, the SNPs of ZNF259 rs2075290 and BUD13 rs10790162 were associated with serum TG levels; ZNF259 rs2075290 was associated with low-density lipoprotein cholesterol and the ApoA1/ApoB ratio (P < 0.006–0.001). Significant linkage disequilibria were noted among ZNF259 rs2075290 and rs964184 and BUD13 rs10790162, and between MLXIPL rs3812316 and rs13235543 (r² > 0.05, P < 0.001). The haplotypes of A-C-G-A-C (rs2075290A-rs964184C-rs10790162G-rs17119975A-rs11556024C) and C-C-C-C (rs799161C-rs35332062C-rs3812316C-rs13235543C) accounted for over half of the % haplotype of each ethnic group.

Association of the variants in the BUD13-ZNF259 genes and the risk of hyperlipidaemia

The single nucleotide polymorphisms (SNPs) in the BUD13 homolog (BUD13) and zinc finger protein 259 (ZNF259) genes have been associated with one or more serum lipid traits in the European populations. However, little is known about such association in the Chinese populations. Our objectives were to determine the association of the BUD13/ZNF259 SNPs and their haplotypes with hypercholesterolaemia (HCH)/hypertriglyceridaemia (HTG) and to identify the possible gene–gene interactions among these SNPs. Genotyping of 6 SNPs was performed in 634 hyperlipidaemic and 547 normolipidaemic participants. The ZNF259 rs2075290, ZNF259 rs964184 and BUD13 rs10790162 SNPs were significantly associated with serum lipid levels in both HCH and non-HCH populations (P < 0.008–0.001). On single locus analysis, only BUD13 rs10790162 was associated with HCH (OR: 2.23, 95% CI: 1.05, 4.75, P = 0.015). The G-G-A-A-C-C haplotype, carrying rs964184-G-allele, was associated with increased risk of HCH (OR: 1.35, 95% CI: 1.10, 1.66, P = 0.005) and HTG (OR: 1.75, 95% CI: 1.39, 2.21, P= 0.000). The A-C-G-G-C-C and A-C-A-G-T-C haplotypes, carrying rs964184-C-allele, were associated with reduced risk of HCH (OR: 0.77, 95% CI: 0.61, 0.99, P = 0.039 and OR: 0.66, 95% CI: 0.47, 0.94, P= 0.021 respectively). On multifactor dimensionality reduction analyses, the two- to three-locus models showed a significant association with HCH and HTG (P < 0.01–0.001). The BUD13/ZNF259 SNPs, which were significant in the European populations, are also replicable in the Southern Chinese population. Moreover, inter-locus interactions may exist among these SNPs. However, further functional studies are required to clarify how these SNPs and genes actually affect the serum lipid levels.

Sex-specific association of the zinc finger protein 259 rs2075290 polymorphism and serum lipid levels

BACKGROUND

Little is known about the association of ZNF259 rs2075290 single nucleotide polymorphism (SNP) and serum lipid levels in the Chinese population. This study aimed to detect the association of ZNF259 rs2075290 SNP and environmental factors with serum lipid levels between males and females in the Mulao and Han populations.

METHODS AND RESULTS

Genotyping of ZNF259 rs2075290 SNP was performed in 788 of Mulao and 778 of Han participants using polymerase chain reaction and restriction fragment length polymorphism. The genotype frequencies were significantly different between Mulao and Han populations (AA, 50.1% Vs 58.9%; AG, 42.3% Vs 35.7%; GG, 7.6% Vs 5.4%, P = 0.002) and between Han males and females (AA, 64.5% Vs 55.2%; AG, 28.3% Vs 40.6%; GG, 7.2% Vs 4.2%, P = 0.001). Serum levels of triglyceride (TG) in Mulao males, and total cholesterol (TC), TG and low-density lipoprotein cholesterol (LDL-C) in Mulao females were different between the AA and AG/GG genotypes (P < 0.05-0.001). Serum TC, LDL-C and apolipoprotein (Apo) A1 levels in Han males, and TG and ApoB levels and ApoA1/ApoB ratio in Han females were different between the AA and AG/GG genotypes (P < 0.05-0.001). An interaction between ZNF259 rs2075290 polymorphism and male gender on serum TC, LDL-C, and ApoA1 levels was noted in Han population (P < 0.05-0.01) but not in Mulao's.

CONCLUSIONS

The subjects with AG/GG genotype in Mulao males and females and Han females have less favorable lipid profiles than those with AA genotype. In contrast, the subjects with AG/GG genotype in Han males have more favorable lipid profiles than those with AA genotype. These findings suggest that the association between ZNF259 rs2075290 SNP and serum lipid levels might have ethnic- and/or sex-specificity.

Association of the KLF14 rs4731702 SNP and serum lipid levels in the Guangxi Mulao and Han populations

The objective of the present study was to detect the association of the rs4731702 single nucleotide polymorphism (SNP) and serum lipid levels in the Guangxi Mulao and Han populations. A total of 727 subjects of Mulao and 740 subjects of Han Chinese were included. Serum low-density lipoprotein cholesterol (LDL-C) and apolipoprotein (Apo) B levels were higher in Mulao than in Han (P < 0.05). The T allele carriers had higher serum LDL-C and ApoAI levels in Mulao, whereas they had lower high-density lipoprotein cholesterol (HDL-C) levels and ratio of ApoAI to ApoB in Han (P < 0.05) than the T allele noncarriers. Subgroup analyses showed that the T allele carriers had higher HDL-C, LDL-C, and ApoAI levels in Mulao males and lower ApoAI levels and ratio of ApoAI to ApoB in Han males than the T allele noncarriers. The subjects with TT genotype in Han females also had higher total cholesterol, LDL-C, ApoAI, and ApoB levels than the subjects with CT or CC genotype. Serum lipid parameters were also correlated with several environmental factors in both ethnic groups. The differences in the association of KLF14 rs4731702 SNP and serum lipid levels between the two ethnic groups might partly result from different gene-environmental interactions.

Macrophages control innate inflammation

Macrophages play a critical role in the pathogenesis of metabolic diseases including gout and type 2 diabetes. The Nod-like receptor (NLR) family, pyrin domain containing 3 (NLRP3) forms the inflammasome with apoptosis-associated speck-like protein containing a CARD (ASC), the adaptor protein, and mediates inflammatory responses by macrophages. By compound screening, we found that tubulin polymerization inhibitors suppress NLRP3 inflammasome activation. NLRP3 inflammasome inducers reduce the NAD(+) level to inactivate the α-tubulin deacetylase Sirtuin 2, resulting in accumulation of acetylated α-tubulin. Acetylated α-tubulin mediates mitochondrial transport and subsequent proximity of ASC on mitochondria to NLRP3 on the endoplasmic reticulum. Thus, microtubule-driven transport of mitochondria is required for NLRP3 inflammasome activation. Macrophages are comprised of two subsets, M1 (inflammatory) and M2 (anti-inflammatory). Trib1 is an adaptor protein involved in protein degradation of immune-related transcription factors. We found that Trib1 is critical for the differentiation of F4/80(+) MR(+) tissue-resident M2-like macrophages. Mice lacking Trib1 in haematopoietic cells show severe lipodystrophy owing to increased lipolysis, even on a normal diet. In response to a high-fat diet, the mice show hypertriglyceridaemia and insulin resistance, together with increased proinflammatory cytokine production. Thus, Trib1 is critical for adipose tissue maintenance and suppression of metabolic disorders by controlling the differentiation of tissue-resident M2-like macrophages.

Critical role of Trib1 in differentiation of tissue-resident M2-like macrophages

Macrophages consist of at least two subgroups, M1 and M2 (refs 1-3). Whereas M1 macrophages are proinflammatory and have a central role in host defence against bacterial and viral infections, M2 macrophages are associated with responses to anti-inflammatory reactions, helminth infection, tissue remodelling, fibrosis and tumour progression. Trib1 is an adaptor protein involved in protein degradation by interacting with COP1 ubiquitin ligase. Genome-wide association studies in humans have implicated TRIB1 in lipid metabolism. Here we show that Trib1 is critical for the differentiation of F4/80(+)MR(+) tissue-resident macrophages--that share characteristics with M2 macrophages (which we term M2-like macrophages)--and eosinophils but not for the differentiation of M1 myeloid cells. Trib1 deficiency results in a severe reduction of M2-like macrophages in various organs, including bone marrow, spleen, lung and adipose tissues. Aberrant expression of C/EBPα in Trib1-deficient bone marrow cells is responsible for the defects in macrophage differentiation. Unexpectedly, mice lacking Trib1 in haematopoietic cells show diminished adipose tissue mass accompanied by evidence of increased lipolysis, even when fed a normal diet. Supplementation of M2-like macrophages rescues the pathophysiology, indicating that a lack of these macrophages is the cause of lipolysis. In response to a high-fat diet, mice lacking Trib1 in haematopoietic cells develop hypertriglyceridaemia and insulin resistance, together with increased proinflammatory cytokine gene induction. Collectively, these results demonstrate that Trib1 is critical for adipose tissue maintenance and suppression of metabolic disorders by controlling the differentiation of tissue-resident M2-like macrophages.

Association of rs2072183 SNP and serum lipid levels in the Mulao and Han populations

Background

Niemann-pick C1-like 1 (NPC1L1) is a key protein for intestinal cholesterol transportation. Common single nucleotide polymorphisms (SNPs) in the NPC1L1 gene have been associated with cholesterol absorption and serum lipid levels. The present study was undertaken to explore the possible association of NPC1L1 rs2072183 1735 C > G SNP and several environmental factors with serum lipid levels in the Mulao and Han populations.

Methods

Genotyping of the rs2072183 SNP was performed in 688 subjects of Mulao and 738 participants of Han Chinese. The interactions between NPC1L1 1735 C > G polymorphism and several environmental factors on serum lipid phenotypes were tested using the factorial design covariance analysis after controlling for potential confounders.

Results

The frequency of G allele was lower in Mulao than in Han (29.72% vs. 37.26%, P < 0.001). The frequency of CC, CG and GG genotypes was 49.85%, 40.84% and 9.31% in Mulao, and 39.30%, 46.88% and 13.82% in Han (P < 0.001); respectively. The levels of low-density lipoprotein cholesterol (LDL-C), apolipoprotein (Apo) B and the ratio of ApoAI/ApoB in Han but not in Mulao were different among the three genotypes (P < 0.05 for all), the subjects with GG and CG genotypes had higher LDL-C, ApoB levels and lower ApoAI/ApoB ratio than the subjects with CC genotype. Subgroup analysis showed that the G allele carriers in Han had higher total cholesterol (TC), LDL-C and ApoB levels in males (P < 0.05) and lower ApoAI/ApoB ratio in both sexes (P < 0.05) than the G allele noncarriers. The G allele carriers in Mulao had higher TC and LDL-C levels in males (P < 0.05) and lower high-density lipoprotein cholesterol (HDL-C) levels in both sexes (P < 0.05) than the G allele noncarriers. Serum TC, LDL-C, ApoB levels and ApoAI/ApoB ratio were correlated with genotypes in Han males (P < 0.05) but not in females. Serum lipid parameters were also correlated with several environmental factors. The genotypes of rs2072183 SNP were interacted with gender or cigarette smoking to influence serum TC and HDL-C levels in Mulao, whereas the genotypes of rs2072183 SNP were interacted with several environmental factors to influence all seven lipid traits in Han (P < 0.05-0.01).

Conclusions

The present study suggests that the rs2072183 SNP in NPC1L1 gene and its association with serum lipid profiles are different between the Mulao and Han populations. The difference in serum lipid profiles between the two ethnic groups might partly result from different rs2072183 SNP or NPC1L1 gene-environmental interactions.

ATP-binding cassette transporter G5 and G8 polymorphisms and several environmental factors with serum lipid levels

Background

The association of ATP-binding cassette (ABC) transporter single nucleotide polymorphisms (SNPs) and serum lipid profiles is inconsistent. The present study was undertaken to detect the association of ABCG5/G8 SNPs and several environmental factors with serum lipid levels.

Methodology/Principal Findings

Genotyping of the ABCG5 (rs4131229 and rs6720173) and ABCG8 (rs3806471 and rs4148211) SNPs was performed in 719 unrelated subjects of Mulao nationality and 782 participants of Han nationality. There were no differences in the genotypic and allelic frequencies of four SNPs between the two ethnic groups besides the genotypic frequencies of rs4131229 SNP in Han. The levels of triglyceride (TG), apolipoprotein (Apo) A1, and ApoA1/ApoB ratio (rs4131229); low-density lipoprotein cholesterol (LDL-C) and ApoB (rs6720173); high-density lipoprotein cholesterol (HDL-C), ApoA1, ApoB, and ApoA1/ApoB ratio (rs3806471); and HDL-C, ApoA1, and ApoA1/ApoB ratio (rs4148211) in Han were different among their genotypes (P<0.05–0.001). The levels of LDL-C (rs6720173) and ApoA1 (rs3806471) in Mulao were also different among their genotypes (P<0.05 for each). The levels of TC, TG, HDL-C, ApoA1, and ApoA1/ApoB ratio (rs4131229); LDL-C and ApoB (rs6720173); HDL-C, ApoA1, and ApoA1/ApoB ratio (rs3806471); and TG, HDL-C, ApoA1, and ApoA1/ApoB ratio (rs4148211) in Han males; and ApoA1/ApoB ratio (rs4131229); LDL-C, ApoB, and ApoA1/ApoB ratio (rs3806471); HDL-C, ApoA1, and ApoA1/ApoB ratio (rs4148211) in Han females were different between the genotypes (P<0.05–0.001). The levels of LDL-C in Mulao females were also different between GG and GC/CC genotypes of rs6720173 (P<0.05). The correlation between serum lipid parameters and genotypes of four SNPs was observed in Han, especially in Han males. Serum lipid parameters were also correlated with several environmental factors.

Conclusions

The associations of four ABCG5/G8 SNPs and serum lipid levels are different between the Mulao and Han populations, or between males and females, suggesting that there may be a racial/ethnic- and/or sex-specific association between ABCG5/G8 SNPs and some serum lipid parameters.