Association of single nucleotide polymorphisms in TCF2 with type 2 diabetes susceptibility in a Han Chinese population

The Role of Hexokinase Domain Containing Protein-1 in Glucose Regulation During Pregnancy

PURPOSE OF REVIEW

Gestational diabetes mellitus (GDM) is a common pregnancy complication conferring an increased risk to the individual of developing type 2 diabetes. As such, a thorough understanding of the pathophysiology of GDM is warranted. Hexokinase domain containing protein-1 (HKDC1) is a recently discovered protein containing hexokinase activity which has been shown to be associated with glucose metabolism during pregnancy. Here, we discuss recent evidence suggesting roles for the novel HKDC1 in gestational glucose homeostasis and the development of GDM and overt diabetes.

RECENT FINDINGS

Genome-wide association studies identified variants of the HKDC1 gene associated with maternal glucose metabolism. Studies modulating HKDC1 protein expression in pregnant mice demonstrate that HKDC1 has roles in whole-body glucose utilization and nutrient balance, with liver-specific HKDC1 influencing insulin sensitivity, glucose tolerance, gluconeogenesis, and ketone production. HKDC1 has important roles in maintaining maternal glucose homeostasis extending beyond traditional hexokinase functions and may serve as a potential therapeutic target.

Serum magnesium, hepatocyte nuclear factor 1β genotype and post-transplant diabetes mellitus: a prospective study

BACKGROUND

Retrospective studies suggest that tacrolimus-induced hypomagnesaemia is a risk factor for post-transplant diabetes mellitus (PTDM), but prospective studies are lacking.

METHODS

This was a prospective study with measurements of serum magnesium and tacrolimus at pre-specified time points in the first year after living donor kidney transplantation (KT). The role of single nucleotide polymorphisms (SNPs) in hepatocyte nuclear factor 1β (HNF1β) was also explored because HNF1β regulates insulin secretion and renal magnesium handling. Repeated measurement and regression analyses were used to analyse associations with PTDM.

RESULTS

In our cohort, 29 out of 167 kidney transplant recipients developed PTDM after 1 year (17%). Higher tacrolimus concentrations were significantly associated with lower serum magnesium and increased risk of hypomagnesaemia. Patients who developed PTDM had a significantly lower serum magnesium trajectory than patients who did not develop PTDM. In multivariate analysis, lower serum magnesium, age and body mass index were independent risk factors for PTDM. In recipients, the HNF1β SNP rs752010 G > A significantly increased the risk of PTDM [odds ratio (OR) = 2.56, 95% confidence interval (CI) 1.05-6.23] but not of hypomagnesaemia. This association lost significance after correction for age and sex (OR = 2.24, 95% CI 0.90-5.57). No association between HNF1β SNPs and PTDM was found in corresponding donors.

CONCLUSIONS

A lower serum magnesium in the first year after KT is an independent risk factor for PTDM. The HNF1β SNP rs752010 G > A may add to this risk through an effect on insulin secretion rather than hypomagnesaemia, but its role requires further confirmation.

Development of a Simple and Cost-Effective Method Based on T7 Endonuclease Cleavage for Detection of Single Nucleotide Polymorphisms

AIMS

Single nucleotide polymorphisms (SNP) can be used as genetic markers and for risk assessment of allele-linked diseases, which can provide information for clinical diagnosis. Large-scale microarray and next-generation sequencing methods have made genome-wide SNP genotyping possible. However, in addition to their high cost, these techniques are dependent on having specialized equipment. Thus, there is a need for a simple genotyping method that can be implemented in a resource-limited environment.

METHODS

We developed a strategy for SNP genotyping based on T7 Endonuclease I cleavage and an enzyme-linked microparticle immune assay. Using this method, we genotyped two common SNP sites (rs11526468 and rs12979860). The quality of the genotyping process was validated.

RESULTS

Although a 70% false-negative rate was observed, no false-positive reactions were found. Therefore, multiple parallel repeat reactions can offset the possibility of mutation detection failure.

DISCUSSION

This method employs a duplicate reagent-dependent procedure, and therefore has the potential for integration into a portable kit for field utilization.

Gestational Diabetes Mellitus: Mechanisms, Treatment, and Complications

Gestational diabetes mellitus (GDM) is the most common metabolic disturbance during pregnancy. The prevalence is rising and correlates with the increase in maternal obesity over recent decades. The etiology of GDM is complex, with genetic and environmental factors implicated in mechanistic and epidemiological studies. GDM begets important short- and long-term health risks for the mother, developing fetus, and offspring. This includes the high likelihood of subsequent maternal type 2 diabetes (T2DM), and possible adverse cardiometabolic phenotypes in the offspring. The most clinically and cost-effective methods of screening for GDM remain uncertain. Whilst treatments with lifestyle and pharmacological interventions have demonstrated short-term benefits, the long-term impact for the offspring of intrauterine exposure to antidiabetic medication remains unclear.

HNF1B, TSPAN8 and NOTCH2 gene polymorphisms in women with gestational diabetes

PURPOSE

To investigate genes involved in pancreatic beta cell function, insulin production and glucose metabolism that may predispose to gestational diabetes mellitus (GDM).

METHODS

The study group consisted of 204 women with GDM and 207 women with normal glucose tolerance (NGT). The following polymorphisms were genotyped for each patient: HNF1B rs4430796, TSPAN8 rs7961581 and NOTCH2 rs10923931. A p value of <.05 was considered to indicate a statistically significant result.

RESULTS

There was a statistically significant increase in the frequency of HNF1B rs4430796 G allele among pregnant women with GDM (GG+AG versus AA, OR: 1.55, 95% CI: 1.01-2.36, p = .042; G versus A, OR: 1.39, 95% CI: 1.06-1.83, p = .018), whereas there were no statistically significant differences in the distributions of TSPAN8 rs7961581 and NOTCH2 rs10923931 genotypes and alleles between women with GDM and healthy pregnant women. In the multivariate logistic regression analysis, older age, higher BMI before pregnancy and a higher number of HNF1B rs4430796 G alleles were independent significant predictors of a higher risk of GDM.

CONCLUSIONS

The results of this study suggest that the HNF1B gene rs4430796 G allele may be associated with increased risk of GDM.

IL-23R mutation is associated with ulcerative colitis: A systemic review and meta-analysis

OBJECTIVES

Since a genome-wide association study revealed that Interleukin-23 receptor (IL-23R) gene is a candidate gene for Ulcerative Colitis (UC), many studies have investigated the association between the IL-23R polymorphisms and UC. However, the results were controversial. The aim of the study was to determine whether the IL-23R polymorphisms confer susceptibility to UC.

METHODS

A systematic literature search was carried out to identify all potentially relevant studies. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were used to estimate the strength of association.

RESULTS

A total of 33 studies in 32 articles, including 10,527 UC cases and 15,142 healthy controls, were finally involved in the meta-analysis. Overall, a significant association was found between all UC cases and the rs11209026A allele (OR = 0.665, 95% CI = 0.604~0.733, P < 0.001). Similarly, meta-analyses of the rs7517847, rs1004819, rs10889677, rs2201841, rs11209032, rs1495965, rs1343151 and rs11465804 polymorphisms also indicated significant association with all UC (all P < 0.05). Stratification by ethnicity revealed that the rs11209026, rs7517847, rs10889677, rs2201841 andrs11465804 polymorphisms were associated with UC in the Caucasian group, but not in Asians, while the rs1004819 and rs11209032 polymorphisms were found to be related to UC for both Caucasian and Asian groups. However, subgroup analysis failed to unveil any association between the rs1495965 and rs1343151 polymorphisms and UC in Caucasians or Asians.

CONCLUSIONS

The meta-analysis suggests significant association between IL-23R polymorphisms and UC, especially in Caucasians.

Associations of genotypes and haplotypes of IL-17 with risk of gastric cancer in an eastern Chinese population

Interleukin-17 plays a crucial role in inflammation-related carcinogenesis. We hypothesize that genetic variants in IL-17 are associated with gastric cancer (GCa) risk, and we genotyped five potentially functional single nucleotide polymorphisms (SNPs) (rs1974226 G > A, rs2275913 A > G, rs3819024 A > G, rs4711998 A > G, and rs8193036 C > T) of IL-17 in 1121 GCa patients and 1216 cancer-free controls in an eastern Chinese population. Logistic regression analysis was used to calculate odds ratios (OR) and 95% confidence intervals (CI). Meta-analysis and genotype-mRNA expression correlation were performed to further validate positive associations. We found that an increased GCa risk was independently associated with rs1974226 (adjusted OR = 2.60, 95% CI = 1.27-5.32 for AA vs. GG + GA) and rs2275913 (adjusted OR = 1.33, 95% CI = 1.03-1.72 for GA + AA vs. GG), while a decreased GCa risk was independently associated with rs3819024 (adjusted OR = 0.72, 95% CI = 0.54-0.96 for GG vs. AA + AG). Additional meta-analyses confirmed the observed risk association with rs2275913. We also found that two IL-17 haplotypes (G-G-G-A-C) and (A-G-G-A-C) (in the order of rs1974226, rs2275913, rs3819024, rs4711998 and rs8193036) were associated with a reduced GCa risk (adjusted OR = 0.64, 95% CI = 0.46-0.89 and adjusted OR = 0.38, 95% CI = 0.17-0.81, respectively). However, the expression Quantitative Trait Locus (eQTL) analysis for the genotype-phenotype correlation did not find mRNA expression changes associated with either the genotypes. In conclusions, genetic variants of IL-17 are likely to be associated with risk of GCa, and additional larger studies with functional validation are needed to explore the molecular mechanisms underlying the observed associations.

Polymorphism in microRNA-binding site in HNF1B influences the susceptibility of type 2 diabetes mellitus: a population based case-control study

Background

Recent genome-wide association studies (GWAS) have identified many SNPs associated with type 2 diabetes mellitus (T2DM). However, the functional roles for most of the SNPs have not been elucidated. MicroRNAs (miRNAs) are key regulators of gene expression involved in the development and progression of various diseases including T2DM. In this study, we investigated whether commonly occurring SNPs modulate miRNA-directed regulation of gene expression, and whether such SNPs in miRNA-binding sites are associated with the susceptibility for T2DM.

Methods

Genotypes of eleven 3′ untranslated region (UTR) SNPs of seven susceptibility genes for T2DM were determined in 353 T2DM patients and 448 control subjects. In addition, the interactions of miRNAs with the 3′UTR in the hepatocyte nuclear factor 1β (HNF1B) gene were investigated using luciferase reporter assays.

Results

One 3′UTR SNP (rs2229295) in the HNF1B gene was significantly associated with T2DM, and the frequency of an A allele (rs2229295) in T2DM patients was decreased compared with that in controls. Luciferase reporter assays showed that the SNP (rs2229295) altered the binding of two miRNAs (hsa-miR-214-5p and hsa-miR-550a-5p).

Conclusions

We have detected the interactions of hsa-miR-214-5p/hsa-miR-550a-5p and the 3′UTR SNP of the HNF1B gene by in vitro luciferase reporter assays, and propose that the binding of such miRNAs regulates the expression of the HNF1B gene and the susceptibility of T2DM.

Electronic supplementary material

The online version of this article (doi:10.1186/s12881-015-0219-5) contains supplementary material, which is available to authorized users.

Association between Gene Polymorphisms of Seven Newly Identified Loci and Type 2 Diabetes and the Correlate Quantitative Traits in Chinese Dong Populations

BACKGROUND

There are much heterogeneity in the genetic variation of type 2 diabetes (T2D). The purpose of this study was to investigate the association of seven novel genetic loci identified in a recent genome-wide association studies (GWAS) with T2D in Chinese Dong populations.

METHODS

A case-controlled study was performed in individuals of Chinese Dong nationality. The genotypes of PARD3B (rs849230), LOC729993 (rs149228), EPHA4 (rs16862811), HNT (rs3099797), PTPRD (rs17584499 and rs649891), TOMM7 (rs2240727) genes were determined using Multiplex PCR-SNaPshot. The independent association between each polymorphism and T2D was assessed using unconditional binary logistic regression analysis (BLR).

RESULTS

A total of 136 cases of T2D and 136 control subjects were enrolled in the study. The polymorphism of rs2240727 in TOMM7 gene was associated with T2D (odds ratio (OR) = 1.65, per copy of the risk T allele, P = 0.004). In addition, CT and TT were risk genotypes for T2D (OR (95% CIs):2.64 (1.28-5.45) and 3.42 (1.58-7.41) respectively). After correcting for multiple testing, the above results remained significant (all P < 0.05). After adjusting for the confounders of age, gender, and BMI, the association between T2D and rs2240727 remained significant (P < 0.01). There were significantly statistical difference in levels of fasting plasm glucose(FPG) among genotypes of rs2240727 in controls and patients, the levels of FPG were significantly higher in CT and TT genotypes than in CC genotype in both groups (all P < 0.05).

CONCLUSIONS

The rs2240727 genetic variant in TOMM7 was associated with T2D of Chinese Dong individuals, and might enhance the risk of T2D by affecting the level of FPG.

An effective method based on real time fluorescence quenching for single nucleotide polymorphism detection

In the Human Genome Project, the most common type of these variations is single nucleotide polymorphisms (SNPs). A large number of different SNP typing technologies have been developed in recent years. Enhancement and innovation for genotyping technologies are currently in progress. We described a rapid and effective method based on real time fluorescence quenching for SNP detection. The new method, Quenching-PCR, offering a single base extension method fully integrated with PCR which used a probe with quencher to eliminate fluorophor of the terminal base according to dideoxy sequencing method. In this platform, dideoxy sequencing reaction and obtaining values of real-time fluorescence occur simultaneously. The assay was validated by 106 DNA templates comparing with Sanger's sequencing and TaqMan assay. Compared with the results of DNA sequencing, the results of Quenching-PCR showed a high concordance rate of 93.40%, while the results of TaqMan platform showed a concordance rate of 92.45%, indicating that Quenching PCR and TaqMan assay were similar in accuracy. Therefore, Quenching PCR will be easily applicable and greatly accelerate the role of SNP detection in physiological processes of human health.

Personalized medicine in Type 2 Diabetes

Type 2 diabetes (T2D) is a global public health concern, its prevalence in Asia, especially Taiwan, rising every year. The risk of developing T2D and diabetes complications is not only controlled by environmental but also by genetic factors. Genetic association studies have shown polymorphisms at specific loci may help identify individuals at greatest risk and response to oral antidiabetic drugs. This review probes effect of genetic profiling on T2D and its complications, using our study population as examples. Also, pharmacogenetics and pharmacogenomics of oral anitdiabetic drug will be explored.

TCF2 attenuates FFA-induced damage in islet β-cells by regulating production of insulin and ROS

Free fatty acids (FFAs) are cytotoxic to pancreatic islet β-cells and play a crucial role in the diabetes disease process. A recent study revealed a down-regulation of transcription factor 2 (TCF2) levels during FFA-mediated cytotoxicity in pancreatic β-cells. However, its function during this process and the underlying mechanism remains unclear. In this study, treatment with palmitic acid (PA) at high levels (400 and 800 μM) decreased β-cell viability and TCF2 protein expression, along with the glucose-stimulated insulin secretion (GSIS). Western and RT-PCR analysis confirmed the positive regulatory effect of TCF2 on GSIS through promotion of the key regulators pancreatic duodenal homeobox-1 (PDX1) and glucose transporter 2 (GLUT2) in β-cells. In addition, both PI3K/AKT and MEK/ERK showed decreased expression in PA (800 μM)-treated β-cells. Overexpression of TCF2 could effectively restore the inhibitory effect of PA on the activation of PI3K/AKT and MEK/ERK as well as β-cell viability, simultaneously, inhibited PA-induced reactive oxygen species (ROS) generation. After blocking the PI3K/AKT and MAPK/ERK signals with their specific inhibitor, the effect of overexpressed TCF2 on β-cell viability and ROS production was obviously attenuated. Furthermore, a protective effect of TCF2 on GSIS by positive modulation of JNK-PDX1/GLUT2 signaling was also confirmed. Accordingly, our study has confirmed that TCF2 positively modulates insulin secretion and further inhibits ROS generation via the PI3K/AKT and MEK/ERK signaling pathways. Our work may provide a new therapeutic target to achieve prevention and treatment of diabetes.