Shengrong Ouyang

Association between MTR A2756G and MTRR A66G polymorphisms and maternal risk for neural tube defects: A meta-analysis

BACKGROUND Methionine synthase (MTR) and methionine synthase reductase (MTRR) genes have been considered to be implicated in the development of neural tube defects (NTDs). However, the results are inconsistent. Accordingly, we conducted a meta-analysis to further investigate such an association. METHODS Published literature from PubMed and Embase databases was retrieved. All studies evaluating the association between MTR A2756G or MTRR A66G polymorphism and maternal risk for NTDs were included. Pooled odds ratio (OR) with 95% confidence interval (CI) was calculated using the fixed- or random-effects model. RESULTS A total of 11 studies (1005 cases and 2098 controls) on MTR A2756G polymorphism and 10 studies (1211 cases and 2003 controls) on MTRR A66G polymorphism were included. Overall, this meta-analysis revealed no significant association between maternal MTR A2756G polymorphism and NTD susceptibility in either genetic model. A significant association between MTRR A66G polymorphism and maternal risk for NTDs was observed for GG vs. AA (OR=1.31, 95% CI 1.03-1.67) among Caucasians. CONCLUSION The present meta-analysis indicated that MTRR A66G polymorphism, but not MTR A2756G, is significantly associated with maternal risk for NTDs in Caucasians.

Association of genomic instability, and the methylation status of imprinted genes and mismatch-repair genes, with neural tube defects

We studied the genomic instability and methylation status of the mismatch-repair (MMR) genes hMLH1 and hMSH2, and the imprinted genes H19/IGF2, in fetuses with neural tube defects (NTDs) to explore the pathogenesis of the disease. Microsatellite instability (MSI) was observed in 23 of 50 NTD patients. Five NTD patients showed high-degree MSI (MSI-H) and 18 showed low-degree MSI (MSI-L). The frequencies of mutated microsatellite loci were 3/50 (6%) for BatT-25, 10/50 (20%) for Bat-26, 3/50 (6%) for Bat34C4, 6/50 (12%) for D2S123, 4/50 (8%) for D2S119, and 3/50 (6%) for D3S1611. The promoter regions of the hMLH1 and hMSH2 genes were unmethylated in NTD patients, as determined by methylation-specific PCR. The hMLH1 and hMSH2 promoter methylation patterns, the methylation levels of H19 DMR1, and IGF2 DMR0 were detected by bisulfite sequencing PCR, sub-cloning, and sequencing. The hMSH2 promoter sequence was unmethylated, and the hMLH1 promoter showed a specific methylation pattern at two CpG sites. The methylation levels of H19 DMR1 in the NTD and control groups are 73.3%±15.9 and 58.3%±11.2, respectively. The methylation level of the NTD group was higher than that of the control group (Students t-test, P<0.05). There is no significant difference in IGF2 DMR0 methylation level between the two groups. All of the results presented here suggest that genomic instability, the MMR system, and hyper-methylation of the H19 DMR1 may be correlated with the occurrence of NTDs.

Cystathionine beta-synthase 844ins68 polymorphism is unrelated to susceptibility to neural tube defects.

OBJECTIVE Cystathionine beta-synthase (CBS) 844ins68 polymorphism has been implicated in the development of neural tube defects (NTDs). However, the results of different studies are inconsistent. Thus, we conducted a meta-analysis to further investigate this association. METHODS Published studies were retrieved from PubMed, Embase, China National Knowledge Infrastructure, and Wanfang Data. Studies that evaluated the association between CBS 844ins68 polymorphism and NTD risk among mothers, children, or fathers were included. The pooled odds ratios with 95% confidence interval were calculated using a fixed effects model or a random effects model. RESULTS A total of eight studies on mothers (641 cases and 1145 controls), eight studies on children (852 cases and 1912 controls), and five studies (263 cases and 1562 controls) on fathers were included. The meta-analysis revealed no significant association between CBS 844ins68 polymorphism and NTD risk among mothers, children, and fathers under either genetic model. CONCLUSION The present meta-analysis indicates that CBS 844ins68 polymorphism is not a good predictor of risk for NTDs.

Meta-analyses on the association of MTR A2756G and MTRR A66G polymorphisms with neural tube defect risks in Caucasian children

Abstract Objective: Methionine synthase (MTR) and MTR reductase (MTRR) genes have been considered to be implicated in the development of neural tube defects (NTDs). The associations between MTR A2756G and MTRR A66G polymorphisms and NTD risk in children have been investigated in many studies. However, results are inconsistent. Accordingly, we conducted meta-analyses to further investigate such associations. Methods: Published literatures were obtained from PubMed and Embase databases. All studies evaluating the association between MTR A2756G or MTRR A66G polymorphism and infant NTDs were included. Pooled odds ratio with a 95% confidence interval was calculated using fixed or random-effects model. Results: A total of 13 studies (1298 cases and 2237 controls) on MTR A2756G polymorphism and 10 studies (1358 cases and 2169 controls) on MTRR A66G polymorphism were included. Meta-analyses reveal no significant association of MTR A2756G and MTRR A66G polymorphisms with risk for NTDs in Caucasian children in either the genetic model or allele model. Conclusions: The present meta-analyses indicate that MTR A2756G and MTRR A66G polymorphism are not associated with NTD risks in Caucasian children.

miR-206-3p Inhibits 3T3-L1 Cell Adipogenesis via the c-Met/PI3K/Akt Pathway

MicroRNAs (miRNAs) are important post-transcriptional regulators during adipocyte adipogenesis. MiR-206-3p, a tissue-specific miRNA, is absent in white adipocytes. In this study, we examined the roles of mmu-miR-206-3p in the adipogenic differentiation of 3T3-L1 preadipocytes. The miR-206-3p expression has shown an apparent decreasing trend after induction, and sustained low expression throughout the differentiation of 3T3-L1 cells. miR-206-3p blocked the adipogenic differentiation of 3T3-L1 cells by attenuating c-Met expression; the inhibition effect of miR-206 to the adipogenic differentiation can be counteracted by restoring c-Met expression. In addition, miR-206-3p decreased the phosphorylation of Akt, which is the downstream effector of c-Met in the PI3K/Akt signaling pathway. These data indicate that miR-206-3p inhibits adipocyte adipogenesis through silencing c-Met and subsequently inactivating the PI3K/Akt signaling pathway.

Distribution of dystrophin gene deletions in a Chinese population

Objective To describe the deletion patterns and distribution characteristics of the dystrophin gene in a Chinese population of patients with Duchenne muscular dystrophy (DMD) or Becker muscular dystrophy (BMD). Methods Patients with DMD/BMD were recruited. Deletions in 19 exons of the dystrophin gene were evaluated using accurate multiplex polymerase chain reaction (PCR). Result Multiplex PCR identified deletions in 238/401 (59.4%) patients with DMD/BMD. Of these, 196 (82.4%) were in the distal hotspot, 32 (13.4%) were in the proximal hotspot, five (2.1%) were in both regions and five (2.1%) were in neither hotspot. Deletions were classified into 54 patterns. Exon 49 was the most frequently deleted. The reading frame rule was upheld for 91.9% of cases. Conclusion Accurate multiplex PCR for 19 exons is an effective diagnostic tool.

Association between serum soluble tumor necrosis factor-α receptors and early childhood obesity.

This study aimed to characterize the inflammatory cytokine profiles and further validate the significantly different cytokines in the serum obtained from obese children aged 36-48 months. Four obese children and four lean controls were randomly selected for inflammatory cytokine array assay, in which two cytokines [soluble tumor necrosis factor-α receptors (sTNFRs) 1 and 2] were found to be significantly different. Both cytokines (sTNFR1 and sTNFR2) were then further validated through enzyme-linked immunosorbent assay (ELISA) in 61 obese children and 52 lean children. ELISA results revealed that serum sTNFR1 level in obese children significantly increased (p = 0.003), whereas sTNFR2 did not change significantly (p = 0.069). Stratified analysis by gender showed that only obese girls presented increased sTNFR1 (p = 0.005) and sTNFR2 (p = 0.049) levels. We conclude that serum sTNFR1 is elevated in early childhood obesity. Moreover, serum sTNFR1 and sTNFR2 are associated with obese girls but not obese boys, thereby suggesting that serum sTNFRs in early childhood obesity may be sex related.

Long Non-Coding RNA Expression Profiling in Obesity Mice with Folic Acid Supplement

Background/Aims: Obesity is a major contributor to the growing prevalence of metabolic and cardiovascular diseases. This study was designed to investigate the effect of folic acid (FA) on obese mice by detecting the genome-wide expression profile of lncRNAs and mRNAs in the heart. Methods: Heart samples were collected from mice fed with standard diet (SD), high-fat diet (HFD) and high-fat diet with FA intake (HFDF). LncRNAs and mRNAs between HFD and HFDF group were analyzed by lncRNA microarray. Nine lncRNAs and mRNAs were validated using quantitative reverse transcription polymerase chain reaction (qRT-PCR). Bioinformatics prediction was used to investigate the potential function of these differentially expressed lncRNAs. Co-expresson analysis was used to determine the transcriptional regulatory relationship of differentially expressed lncRNAs and mRNAs between two groups. Results: The expression of 58,952 lncRNAs and 20,145 mRNAs in HFD and HFDF groups was profiled by using microarrays. Gene Ontology and pathway analyses indicated that the biological functions of differentially expressed mRNAs were related to inflammation, energy metabolism, and cell differentiation. Co-expression networks composed of lncRNAs and mRNAs were also constructed to investigate the potential regulatory roles of differentially expressed lncRNAs on mRNAs. LncRNAs, namely, NONMMUT033847, NONMMUT070811, and NONMMUT015327, were validated through qRT-PCR, and these lncRNAs may be important factors regulating inflammation, energy metabolism, and cell differentiation. The expression levels of Dnajb1, Egr2, Hba-a1, Il1β, Cxcl2, and Tnfsf9 were significantly different between HFD and HFDF. Conclusions: Results suggested that FA may improve the cardiovascular function of obesity and contribute to those lncRNAs associated with inflammation and cell differentiation. In a nutshell, the present study identified a panel of lncRNAs and mRNAs that may be potential biomarkers or drug targets relevant to the high-fat diet related obesity.

Folic acid supplementation alters the DNA methylation profile and improves insulin resistance in high-fat-diet-fed mice

Folic acid (FA) supplementation may protect from obesity and insulin resistance, the effects and mechanism of FA on chronic high-fat-diet-induced obesity-related metabolic disorders are not well elucidated. We adopted a genome-wide approach to directly examine whether FA supplementation affects the DNA methylation profile of mouse adipose tissue and identify the functional consequences of these changes. Mice were fed a high-fat diet (HFD), normal diet (ND) or an HFD supplemented with folic acid (20 μg/ml in drinking water) for 10 weeks, epididymal fat was harvested, and genome-wide DNA methylation analyses were performed using methylated DNA immunoprecipitation sequencing (MeDIP-seq). Mice exposed to the HFD expanded their adipose mass, which was accompanied by a significant increase in circulating glucose and insulin levels. FA supplementation reduced the fat mass and serum glucose levels and improved insulin resistance in HFD-fed mice. MeDIP-seq revealed distribution of differentially methylated regions (DMRs) throughout the adipocyte genome, with more hypermethylated regions in HFD mice. Methylome profiling identified DMRs associated with 3787 annotated genes from HFD mice in response to FA supplementation. Pathway analyses showed novel DNA methylation changes in adipose genes associated with insulin secretion, pancreatic secretion and type 2 diabetes. The differential DNA methylation corresponded to changes in the adipose tissue gene expression of Adcy3 and Rapgef4 in mice exposed to a diet containing FA. FA supplementation improved insulin resistance, decreased the fat mass, and induced DNA methylation and gene expression changes in genes associated with obesity and insulin secretion in obese mice fed a HFD.

Effects of macrophages and CXCR2 on adipogenic differentiation of bone marrow mesenchymal stem cells: CAO et al.

Macrophages and many chemokines are closely associated with the adipogenic differentiation of bone marrow mesenchymal stem cells (MSCs), but their roles in adipogenesis and the underlying mechanisms are not fully understood. Here, we first investigated the influence of macrophages on the differentiation of MSCs in vitro. We found that RAW246.7 macrophages cocultured with MSCs strongly blocked the differentiation progress and inhibited the expression of C‐X‐C motif chemokine ligand 1 (CXCL1) during adipogenesis. Coculture with MSCs mainly induced macrophages toward M2 polarization. In addition, the expression of CXCL1 and its receptor, C‐X‐C chemokine receptor type 2, CXCR2 are high during adipogenic differentiation of MSCs and not in mature adipocytes. Although CXCL1 had no effect on adipogenesis, treatment with a specific CXCR2 inhibitor, SB225002, hampered the adipogenic differentiation of MSCs. Blocking CXCR2 decreased p38 and Elk1 phosphorylation but increased the extracellular signal–regulated kinase (ERK) phosphorylation at the initial stage of adipogenesis, which suppressed the phosphorylation of p38/ERK‐Elk1 at the late stage. Inhibition of ERK had similar effects on adipogenesis and Elk1 phosphorylation. Our data suggest that MSCs interact with macrophages during adipogenic differentiation. CXCR2 regulates the adipogenic differentiation of MSCs by altering the activation of the p38/ERK‐Elk1 signaling pathway.