ENPP1 K121Q polymorphism and type 2 diabetes mellitus in the Chinese population: a meta-analysis including 11,855 subjects

Epitranscriptomic regulation of lipid oxidation and liver fibrosis via ENPP1 mRNA m6A modification

BACKGROUND

Dysregulated lipid oxidation occurs in several pathological processes characterized by cell proliferation and migration. Nonetheless, the molecular mechanism of lipid oxidation is not well appreciated in liver fibrosis, which is accompanied by enhanced fibroblast proliferation and migration.

METHODS

We investigated the causes and consequences of lipid oxidation in liver fibrosis using cultured cells, animal models, and clinical samples.

RESULTS

Increased ecto-nucleotide pyrophosphatase/phosphodiesterase (ENPP1) expression caused increased lipid oxidation, resulting in the proliferation and migration of hepatic stellate cells (HSCs) that lead to liver fibrosis, whereas fibroblast-specific ENPP1 knockout reversing these results. Elevated ENPP1 and N6-methyladenosine (m6A) levels were associated with high expression of Wilms tumor 1 associated protein (WTAP). Mechanistically, WTAP-mediated m6A methylation of the 3'UTR of ENPP1 mRNA and induces its translation dependent of YTH domain family proteins 1 (YTHDF1). Additionally, ENPP1 could interact with hypoxia inducible lipid droplet associated (HILPDA) directly; overexpression of ENPP1 further recruits HILPDA-mediated lipid oxidation, thereby promotes HSCs proliferation and migration, while inhibition of ENPP1 expression produced the opposite effect. Clinically, increased expression of WTAP, YTHDF1, ENPP1, and HILPDA, and increased m6A mRNA content, enhanced lipid oxidation, and increased collagen deposition in human liver fibrosis tissues.

CONCLUSIONS

We describe a novel mechanism in which WTAP catalyzes m6A methylation of ENPP1 in a YTHDF1-dependent manner to enhance lipid oxidation, promoting HSCs proliferation and migration and liver fibrosis.

Current Studies on Molecular Mechanisms of Insulin Resistance

Diabetes is a metabolic disease that raises the risk of microvascular and neurological disorders. Insensitivity to insulin is a characteristic of type II diabetes, which accounts for 85-90 percent of all diabetic patients. The fundamental molecular factor of insulin resistance may be impaired cell signal transduction mediated by the insulin receptor (IR). Several cell-signaling proteins, including IR, insulin receptor substrate (IRS), and phosphatidylinositol 3-kinase (PI3K), have been recognized as being important in the impaired insulin signaling pathway since they are associated with a large number of proteins that are strictly regulated and interact with other signaling pathways. Many studies have found a correlation between IR alternative splicing, IRS gene polymorphism, the complicated regulatory function of IRS serine/threonine phosphorylation, and the negative regulatory role of p85 in insulin resistance and diabetes mellitus. This review brings up-to-date knowledge of the roles of signaling proteins in insulin resistance in order to aid in the discovery of prospective targets for insulin resistance treatment.

SIRT1-SIRT7 in Diabetic Kidney Disease: Biological Functions and Molecular Mechanisms

Diabetic kidney disease (DKD) is a severe microvascular complication in patients with diabetes and is one of the main causes of renal failure. The current clinical treatment methods for DKD are not completely effective, and further exploration of the molecular mechanisms underlying the pathology of DKD is necessary to improve and promote the treatment strategy. Sirtuins are class III histone deacetylases, which play an important role in many biological functions, including DNA repair, apoptosis, cell cycle, oxidative stress, mitochondrial function, energy metabolism, lifespan, and aging. In the last decade, research on sirtuins and DKD has gained increasing attention, and it is important to summarize the relationship between DKD and sirtuins to increase the awareness of DKD and improve the cure rates. We have found that miRNAs, lncRNAs, compounds, or drugs that up-regulate the activity and expression of sirtuins play protective roles in renal function. Therefore, in this review, we summarize the biological functions, molecular targets, mechanisms, and signaling pathways of SIRT1-SIRT7 in DKD models. Existing research has shown that sirtuins have the potential as effective targets for the clinical treatment of DKD. This review aims to lay a solid foundation for clinical research and provide a theoretical basis to slow the development of DKD in patients.

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 of the ENPP1/ENTPD1 Polymorphisms in Hemodialysis Patients

Introduction

ENPP1 and ENTPD1 are two main enzymes involved in ATP-AMP-ADP-adenosine axis, which is associated with lipid metabolism, diabetes mellitus (DM) and renal fibrosis. The single nucleotide polymorphisms (SNPs) of ENPP1 and ENTPD1, rs1044498 and rs6584026, are associated with these factors. This retrospective study aimed to address the two SNPs variants in hemodialysis (HD) patients and analyzes their relations with clinical characteristics.

Methods

This study included 543 regular HD patients over 3 months at our center. Overnight fasting peripheral blood sample was taken from each subject to extract the DNA. The genotypes of rs1044498 and rs6584026 were detected by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. The basic clinical data were noted such as sex, age, and HD-age, and the main causes of chronic kidney disease (CKD) and the clinical characteristics were collected on average at least three times in half a year. T-test and Chi-test were performed for the statistical analyses. Binary logistic regression was applied for the significant parameters by excluding the confounders, gender, age and HD-age. All statistical tests were considered significant for P<0.05.

Results

The rs1044498 genotypes showed in two types, A/A and A/C without C/C. The rs6584026 genotypes were C/C and C/T without T/T. The genotype frequency of rs1044498 (A/C) was 0.238, and the genotype frequency of rs6584026 (C/T) was 0.328. The age and the level of lipoprotein α showed statistical significance with rs1044498 variant (A/C, P<0.05). The rs6584026 variant (C/T) was frequently found in patients with nephritis (P<0.05). The albumin, alkaline phosphatase (ALP), lipoprotein α, cholesterol, apolipoprotein B (Apo B), Apo B/A1 and nephritis were independently associated with rs6584026 variant (C/T, P<0.05) in binary logistic regression model by controlling the confounders of gender, age and HD-age. High level of triglyceride and low level of urine nitrogen were related to rs6584026 variant (C/T, P<0.05).

Conclusion

The rs1044498 and rs6584026 SNPs were related to several high levels of lipids, and rs6584026 variant was related to nephritis and autoimmune disease. The rs6584026 SNP may contribute to the increased risks of cholesterol and ApoB/A1 in HD patients.

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

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

Risk of Obesity-Related Cardiometabolic Complications in Special Populations: A Crisis in Asians

The prospect of a significant increase in global health-related costs associated with high cardiometabolic complications of obesity in Asians has encouraged more attention to be focused on the problem of growing obesity prevalence in these populations. Although these studies have shown that cardiometabolic complications occur more frequently and at a lower body mass index (BMI) in Asians than in European populations, the mechanisms involved have yet to be discovered. Ethnic/racial differences in body composition and fat distribution have been studied extensively. Although these studies have shown that increasing BMI is associated with larger increases in body fat content in Asians, growing evidence points to factors other than body fat content and fat distribution in determining a higher prevalence of cardiometabolic complications in these populations. Here, we provide support to our view that earlier onset of adipocyte maturation arrest/insulin resistance during weight gain could be a major factor in increasing the cardiometabolic risk of Asian populations at a lower BMI.

The ENPP1 K121Q polymorphism is associated with type 2 diabetes and related metabolic phenotypes in a Taiwanese population

Increased risk of developing type 2 diabetes (T2D) has been associated with a single nucleotide polymorphism (SNP), rs1044498 (K121Q), in the ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1) gene, but this association is unclear among Asians. In this replication study, we reassessed whether the ENPP1 rs1044498 SNP is associated with T2D, obesity, and T2D/obesity-related metabolic traits in a Taiwanese population. A total of 1513 Taiwanese subjects were assessed in this study. The ENPP1 rs1044498 SNP was genotyped by the Taqman assay. T2D/Obesity-related quantitative traits, such as waist circumference and fasting glucose, were measured. Our data showed a significant association of the ENPP1 rs1044498 SNP with T2D (P < 0.001) among the subjects. Moreover, the ENPP1 rs1044498 SNP was significantly associated with T2D/obesity-related metabolic traits, such as waist circumference (P = 0.002) and fasting glucose (P < 0.001), among the subjects. However, we found no association of ENPP1 rs1044498 with obesity (BMI ≧ 27 kg/m(2)). Our study indicates that the ENPP1 rs1044498 SNP is associated with T2D, waist circumference, and fasting glucose in Taiwanese subjects.

Contribution of ENPP1, TCF7L2, and FTO polymorphisms to type 2 diabetes in mixed ancestry ethnic population of South Africa

BACKGROUND

Transcription factor 7-like 2 gene (TCF7L2), fat mass and obesity-associated gene (FTO), and ectonucleotide pyrophosphatase/phosphodiesterase gene (ENPP1) are known risk loci for type 2 diabetes (T2DM) mostly in European populations.

OBJECTIVES

To assess the association of these genes with T2DM risk in a South African mixed-ancestry population.

METHODS

Five hundred and sixty six participants were genotyped for ENPP1-rs997509 and -rs1044498, FTO-9941349 and -rs3751812, TCF7L2-rs12255372 and -rs7903146 polymorphisms using Taqman genotyping assays and validated by automated sequencing to assess the association of the polymorphisms with cardiometabolic traits.

RESULTS

In logistic regression models adjusted for age, sex, body mass index (BMI) and insulin resistance, minor allele of rs997509 was associated with a higher risk of prevalent T2DM under a recessive model [odd ratio 4.60 (95% confidence interval: 1.07 to 19.86); p = 0.040].Under additive model, the rs7903146 [1.43 (1.00 to 2.04); p= 0.053] and rs9941349 [1.43 (1.00 to 2.04); p = 0.052] minor alleles showed marginally significant associations with a high risk of T2DM. However, only the rs7903146 alleles (p=0.011) and genotypes (p=0.025) distributions were statistically significantly different between diabetic and non-diabetic individuals.

CONCLUSION

Our findings demonstrate that ENPP1, TCF7L2, and FTO may predispose to T2DM in the mixed-ancestry population.

Association between the ENPP1 K121Q polymorphism and risk of diabetic kidney disease: a systematic review and meta-analysis

The potential association between the K121Q (A/C, rs1044498) polymorphism in the ectonucleotide pyrophosphatase/phosphodiesterase (ENPP1) gene and risk of diabetic kidney disease (DKD) has been investigated. Nevertheless, the effect of this variant on DKD risk is still under debate, and conflicting results have been reported. To this date, no meta-analysis has evaluated the association of the K121Q polymorphism with DKD. This paper describes the first meta-analysis conducted to evaluate whether the ENPP1K121Q polymorphism is associated with DKD. A literature search was conducted to identify all case-control or cross-sectional studies that evaluated associations between the ENPP1K121Q polymorphism and DKD. Pooled odds ratios (OR) and 95% confidence intervals (95% CI) were calculated for allele contrast, additive, dominant and recessive inheritance models. Seven studies were eligible for inclusion in the meta-analysis, providing data on 3571 type 1 or type 2 diabetic patients (1606 cases with DKD and 1965 diabetic controls without this complication). No significant heterogeneity was observed among the studies included in the meta-analysis when assuming different inheritance models (I² < 50% or P > 0.10 for the entire sample and after stratification by ethnicity). Meta-analysis results revealed significant associations between the K121Q polymorphism and risk of DKD in Asians and Europeans when assuming the different inheritance models analyzed. The most powerful association was observed for the additive model (OR = 1.74, 95% CI 1.27-2.38 for the total sample). In conclusion, the present meta-analysis detected a significant association between the ENPP1K121Q polymorphism and increased susceptibility of DKD in European and Asian populations.

Influence of apolipoprotein E gene polymorphism on development of type 2 diabetes mellitus in Chinese Han population: a meta-analysis of 29 studies

OBJECTIVES

Published data regarding the association between apolipoprotein E (ApoE) gene polymorphism and type 2 diabetes mellitus (T2DM) risk in Chinese Han population were inconclusive. To derive a more precise estimation of the relationship between this variant and T2DM risk in Chinese Han population, we performed this meta-analysis.

DESIGN AND METHODS

A computerized literature search was conducted to identify the relevant studies from PubMed, EMbase, Web of Science, CBMdisc, CNKI, and Google Scholar. Additionally, hand searching of the references of identified articles was performed. All the statistical tests were performed using Stata 11.0.

RESULTS

A total of 29 articles with 4615 T2DM cases and 2867 controls were included in the present meta-analysis. The results showed evidence for significant association between ApoE gene polymorphism and T2DM risk (for ε2/ε3 vs. ε3/ε3: OR=1.37, 95% CI=1.12-1.68, P<0.01; for ε3/ε4 vs. ε3/ε3: OR=1.53, 95% CI=1.23-1.91, P<0.01; for ε4/ε4 vs. ε3/ε3: OR=1.86, 95% CI=1.22-2.84, P<0.01; for ε2 allele vs. ε3 allele: OR=1.28, 95% CI=1.08-1.52, P=0.01; for ε4 allele vs. ε3 allele: OR=1.43, 95% CI=1.22-1.68, P<0.01). In addition, significant association was also found between ApoE gene polymorphism and diabetic nephropathy (DN) risk.

CONCLUSIONS

The results of this meta-analysis suggest that the ApoE ε2 and ε4 alleles may be associated with increased risks of T2DM and DN in Chinese Han population. Additional well-designed genome-wide association studies are required to confirm these results.

Association of the ENPP1 K121Q polymorphism with susceptibility to type 2 diabetes in different populations: evidence based on 40 studies

The K121Q gene polymorphism of ectoenzyme nucleotide pyrophosphate phosphodiesterase 1(ENPP1) has been widely investigated, however, results have been somewhat conflicting. The aim of this meta-analysis was to establish a precise estimation of the association between ENPP1 gene polymorphisms and type 2 diabetes (T2D). A literature search in PubMed, Embase, Cochrane Library and China Biology Medicine (CBM) databases was conducted on publications published prior to November 21(st), 2013. The combined odds ratio (OR) with 95% confidence intervals (95% CI) was calculated to estimate the strength of the association using a random-effects/fixed-effects model. Statistical analyses were performed using the STATA 11.0 software. For the overall population, there was a significant association between ENPP1 gene polymorphisms and T2D when comparing the Q allele versus K allele (OR = 1.29, 95% CI 1.16-1.44, p = 0.000). Considering diverse ethnic groups, effect sizes were consistent for patients of Caucasian and Asian descent (OR = 1.20, 95% CI = 1.08-1.33 and OR = 1.47, 95% CI = 1.15-1.89, respectively); however, effect size was not consistent for those of African descent. Under other models of inheritance, significant associations were also observed. Sensitivity analyses did not leading to differing he results. In summary, the Q allele of the ENPP1 K121Q gene may contribute to the susceptibility for T2D in Caucasians and Asians.

CDKAL1 gene rs7756992 A/G polymorphism and type 2 diabetes mellitus: a meta-analysis of 62,567 subjects

The Cyclin-dependent kinase 5 regulatory subunit-associated protein 1-like (CDKAL1) gene rs7756992 A/G polymorphism has been suggested to be associated with type 2 diabetes mellitus (T2DM), but the individual studies results are still controversial. To explore the association of CDKAL1 gene rs7756992 A/G polymorphism with T2DM, a meta-analysis involving 62,567 subjects from 21 separate studies was conducted. In the whole population, a significant association was found between CDKAL1 gene rs7756992 A/G polymorphism and T2DM under allelic (OR: 1.180, 95% CI: 1.130–1.230, P = 1.60 × 10⁻¹⁴), recessive (OR: 1.510, 95% CI: 1.380–1.660, P = 8.41 × 10⁻¹⁸), dominant (OR: 1.175, 95% CI: 1.109–1.246, P = 6.30 × 10⁻⁸), homozygous (OR: 1.400, 95% CI: 1.282–1.530, P = 8.02 × 10⁻¹⁴), and heterozygous genetic models (OR: 1.101, 95% CI: 1.040–1.166, P = 0.001). CDKAL1 gene rs7756992 A/G polymorphism was significantly associated with T2DM. The person with G allele of CDKAL1 gene rs7756992 A/G polymorphism might be predisposed to T2DM.

Contribution of common variants of ENPP1, IGF2BP2, KCNJ11, MLXIPL, PPARγ, SLC30A8 and TCF7L2 to the risk of type 2 diabetes in Lebanese and Tunisian Arabs

BACKGROUND

While several type 2 diabetes mellitus (T2DM) susceptibility loci identified through genome-wide association studies (GWAS) have been replicated in many populations, their association in Arabs has not been reported. For this reason, the present study looked at the contribution of ENNP1 (rs1044498), IGF2BP2 (rs1470579), KCNJ11 (rs5219), MLXIPL (rs7800944), PPARγ (rs1801282), SLC30A8 (rs13266634) and TCF7L2 (rs7903146) SNPs to the risk of T2DM in Lebanese and Tunisian Arabs.

METHODS

Study subjects (case/controls) were Lebanese (751/918) and Tunisians (1470/838). Genotyping was carried out by the allelic discrimination method.

RESULTS

In Lebanese and Tunisians, neither ENNP1 nor MLXIPL was associated with T2DM, whereas TCF7L2 was significantly associated with an increased risk of T2DM in both the Lebanese [P < 0.001; OR (95% CI): 1.38 (1.20-1.59)] and Tunisians [P < 0.001; OR (95% CI): 1.36 (1.18-1.56)]. Differential associations of IGF2BP2, KCNJ11, PPARγ and SLC30A8 with T2DM were noted in the two populations. IGF2BP2 [P = 1.3 × 10(-5); OR (95% CI): 1.66 (1.42-1.94)] and PPARγ [P = 0.005; OR (95% CI): 1.41 (1.10-1.80)] were associated with T2DM in the Lebanese, but not Tunisians, while KCNJ11 [P = 8.0 × 10(-4); OR (95% CI): 1.27 (1.09-1.47)] and SLC30A8 [P = 1.6 × 10(-5); OR (95% CI): 1.37 (1.15-1.62)] were associated with T2DM in the Tunisians, but not Lebanese, after adjusting for gender and body mass index.

CONCLUSION

T2DM susceptibility loci SNPs identified through GWAS showed differential associations with T2DM in two Arab populations, thus further confirming the ethnic contributions of these variants to T2DM susceptibility.