MTHFD1 is critical for the negative regulation of retinoic acid receptor signalling in anencephaly.

Neural tube defects are the most severe congenital malformations that result from failure of neural tube closure during early embryonic development, and the underlying molecular mechanisms remain elusive. Retinoic acid, an active derivative of vitamin A, is critical for neural system development, and retinoic acid receptor (RAR) signalling malfunctions have been observed in human neural tube defects. However, retinoic acid-retinoic acid receptor signalling regulation and mechanisms in neural tube defects are not fully understood. The mRNA expression of RARs and retinoid X receptors in the different human neural tube defect phenotypes, including 11 pairs of anencephaly foetuses, 10 pairs of hydrocephalus foetuses and nine pairs of encephalocele foetuses, was investigated by NanoString nCounter technology. Immunoprecipitation-mass spectrometry was performed to screen the potential interacting targets of retinoic acid receptor γ. The interactions between proteins were confirmed by co-immunoprecipitation and immunofluorescence laser confocal microscopy. Luciferase and chromatin immunoprecipitation with quantitative real-time polymerase chain reaction assays were used to clarify the underlying mechanism. Moreover, a neural tube defect animal model, constructed using excess retinoic acid, was used for further analysis with established molecular biology technologies. We report that level of retinoic acid receptor γ (RARγ) mRNA was significantly upregulated in the brain tissues of human foetuses with anencephaly. To further understand the actions of retinoic acid receptor γ in neural tube defects, methylenetetrahydrofolate dehydrogenase 1 was identified as a specific retinoic acid receptor γ target from IP-MS screening. Additionally, methylenetetrahydrofolate dehydrogenase 1 negatively regulated retinoic acid receptor γ transcription factor activity. Furthermore, low expression of methylenetetrahydrofolate dehydrogenase 1 and activation of retinoic acid receptor signalling were further determined in human anencephaly and a retinoic acid-induced neural tube defect mouse model. This study reveals that methylenetetrahydrofolate dehydrogenase 1, the rate-determining enzyme in the one-carbon cycle, might be a specific regulator of retinoic acid receptors; these findings provide new insights into the functional linkage between nuclear folate metabolism and retinoic acid receptor signalling in neural tube defect pathology.

Polymorphisms of Placental Iodothyronine Deiodinase Genes in a Rural Area of Northern China with High Prevalence of Neural Tube Defects.

INTRODUCTION: We have reported that high total homocysteine and the coexistence of inadequate thyroid hormones in maternal serum increase the risk of fetal neural tube defects (NTDs). Placental iodothyronine deiodinases (DIOs: DIO1, DIO2, and DIO3) play a role in regulating the conversions between different forms of maternal thyroid hormones. This study hypothesized that single nucleotide polymorphisms (SNPs) in placental DIOs genes could be related to NTDs. METHODS: We performed a case-control study from 2007 to 2009 that included pregnant women from Lüliang, Shanxi Province, China. Nine distinct SNPs in DIOs genes were analyzed, and placental samples were obtained from 83 pregnant women with NTD fetuses and 90 pregnant women with normal fetuses. The nine SNPs were analyzed using the Cochran-Armitage test and the Fisher's exact test. RESULTS: There were no statistically significant differences between case and control in the nine SNPs of DIOs (p > 0.05). CONCLUSIONS: The results of this study suggested that SNPs of DIO genes in the placenta among pregnant women have no statistically significant difference between the two groups, suggesting that other factors might be involved in metabolism of maternal thyroid hormone provided to fetuses, such as epigenetic modification of methylation and homocysteinylation and genomic imprinting in the placenta. Further functional studies on placenta samples are necessary.

Method for reconstructing a high dynamic range image based on a single-shot filtered low dynamic range image.

Traditional cameras are limited by sensors and cannot directly capture single-shot high dynamic range (HDR) images. We propose an improved single-shot HDR image reconstruction method that uses a single-exposure filtered low dynamic range (FLDR) image. First, by adding an optical filter in front of the camera lens, a FLDR image with different RGB channel exposure states and luminance ranges can be captured in a single-shot, unlike the traditional LDR image. Second, a deep inverse tone mapping network (DITMnet) with multibranch features extraction and multioutput images synthesis is designed to reconstruct an HDR image from a single FLDR image. Experimentally, under different exposure states and color spaces, our method outperforms similar algorithms.

The effect of folic acid deficiency on FGF pathway via Brachyury regulation in neural tube defects.

Folate deficiency in early development leads to disturbance in multiple processes, including neurogenesis during which fibroblast growth factor (FGF) pathway is one of the crucial pathways. Whether folic acid (FA) directly affects FGF pathways to influence neurodevelopment and the possible mechanism remains unclear. In this study, we presented evidence that in human FA-insufficient encephalocele, the FGF pathway was interfered. Furthermore, in Brachyury knockout mice devoid of such T-box transcription factors regulating embryonic neuromesodermal bipotency and a key component of FGF pathway, change in expression of Brachyury downstream targets, activator Fgf8 and suppressor dual specificity phosphatase 6 was detected, along with the reduction in expression of other key FGF pathway genes. By using a FA-deficient cell model, we further demonstrated that decrease in Brachyury expression was through alteration in hypermethylation at the Brachyury promoter region under FA deficiency conditions, and suppression of Brachyury promoted the inactivation of the FGF pathway. Correspondingly, FA supplementation partially reverses the effects seen in FA-deficient embryoid bodies. Lastly, in mice with maternal folate-deficient diets, aberrant FGF pathway activity was found in fetal brain dysplasia. Taken together, our findings highlight the effect of FA on FGF pathways during neurogenesis, and the mechanism may be due to the low expression of Brachyury gene via hypermethylation under FA-insufficient conditions.-Chang, S., Lu, X., Wang, S., Wang, Z., Huo, J., Huang, J., Shangguan, S., Li, S., Zou, J., Bao, Y., Guo, J., Wang, F., Niu, B., Zhang, T., Qiu, Z., Wu, J., Wang, L. The effect of folic acid deficiency on FGF pathway via Brachyury regulation in neural tube defects.

Quantitative Measurement of PARD3 Copy Number Variations in Human Neural Tube Defects.

Although more than 200 genes are known to be related to neural tube defects (NTDs), the exact molecular basis is still unclear. Evaluating the contribution of copy number variation (CNV) might be a priority because CNV involves changes in the copy number of large segments of DNA, leading to phenotypic traits and disease susceptibility. Recent studies have documented that the polarity protein partitioning defective 3 homolog (Pard3) plays an essential role in the process of neural tube closure. The aim of this study was to assess the role of PARD3 CNVs in the etiology of human NTDs. Relative quantitative PCR and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry were used to quantitative measurement of CNVs in 25 PARD3 exons in 202 NTD cases and 231 controls from a region of China with a high prevalence of NTDs. The results showed that microduplications ranging from 3 to 4 were evident in coding Exon 21 and Exon 25 in both case and control groups. A novel heterozygous microdeletion spanning 444 bp of Exon 14 was identified in two cases of anencephaly and is absent from all controls analyzed. Expression analyses indicated that this heterozygotic microdeletion showed no tissue specificity and led to defective expression of PARD3. Our study provides further evidence implicating PARD3 in the etiology of NTDs.

[Association between the polymorphisms of TMPRSS6 and the levels of serum ferrtin and soluble transferrin receptor in pregnant women in Lüliang Area of Shanxi Province].

OBJECTIVE: To analysis the associations between the polymorphisms of TMPRSS6 and the levels of serum ferritin( SF) and soluble transferrin receptor( s TfR) in pregnant women. METHODS: A total of 807 pregnant women were recruited by using cluster random sampling method from Lüliang in Shanxi Province in 2014. Roche Tinaquant immunoturbidimetric assay was used to measure the level of SF and s TfR, then iron deficiency( ID) was identified by the criteria of SF < 25 ng/m L and s TfR > 4. 4 mg/L, respectively. Sequenom MassArray was used to genotype the 7 targeted single-nucleotide polymorphisms( SNPs)( rs11704654, rs1421312, rs2111833, rs2235321, rs2543519, rs4820268 and rs855791) of the subjects. The t test and ANOVA analysis were used to test the different levels of SF and s TfR among SNPs, and chi-square test and Logistic regression were conducted to detect the associations between genotypes of each locus and ID. RESULTS: The differences of the levels of Ln SF between genotypes in rs2111833 were significant( F = 3. 57, P = 0. 0287), and the Ln SF level of T allele carrier group was lower than CC group( t = 2. 03, P = 0. 0429). The Ln SF level of A allele carrier group was lower than GG carrier group in rs855791( t = 1. 97, P = 0. 0490). For rs11704654, the ratio of SF < 25 ng/m L of T allele carriers was higher than CC carriers( χ~2= 4. 5456, P = 0. 0330). For rs211183, the ratio of SF < 25 ng/m L of T allele carriers was higher than CC carriers( χ~2= 4. 6431, P = 0. 0312). For rs855791, the ratio of SF < 25 ng/m L of GG carriers was lower than A allele carriers( χ~2= 5. 0134, P = 0. 0263). rs11704654( T) and rs855791( A) were still shown the association with SF < 25 ng/m L status in logistic analysis adjusted by age and gestational weeks. The Ln s TfR level of T allele carrier group in rs11704654 was higher than CC carrier group( t =-2. 012, P = 0. 024), and the Ln s TfR level of G allele carrier group in rs2543519 was higher than AA carrier group( t =-1. 954, P = 0. 011). CONCLUSION: The associations between polymorphisms of TMPRSS6 and the levels of SF and s TfR are observed in pregnant women.

Rare Deleterious PARD3 Variants in the aPKC-Binding Region are Implicated in the Pathogenesis of Human Cranial Neural Tube Defects Via Disrupting Apical Tight Junction Formation.

Increasing evidence that mutation of planar cell polarity (PCP) genes contributes to human cranial neural tube defect (NTD) susceptibility prompted us to hypothesize that rare variants of genes in the core apical-basal polarity (ABP) pathway are risk factors for cranial NTDs. In this study, we screened for rare genomic variation of PARD3 in 138 cranial NTD cases and 274 controls. Overall, the rare deleterious variants of PARD3 were significantly associated with increased risk for cranial NTDs (11/138 vs.7/274, P < 0.05, OR = 3.3). These NTD-specific variants were significantly enriched in the aPKC-binding region (6/138 vs. 0/274, P < 0.01). The East Asian cohort in the ExAC database and another Chinese normal cohort further supported this association. Over-expression analysis in HEK293T and MDCK cells confirmed abnormal aPKC binding or interaction for two PARD3 variants (p.P913Q and p.D783G), resulting in defective tight junction formation via disrupted aPKC binding. Functional analysis in human neural progenitor cells and chick embryos revealed that PARD3 knockdown gave rise to abnormal cell polarity and compromised the polarization process of neuroepithelial tissue. Our studies suggest that rare deleterious variants of PARD3 in the aPKC-binding region contribute to human cranial NTDs, possibly by disrupting apical tight junction formation and subsequent polarization process of the neuroepithelium.

Analysis of polymorphisms of genes associated with folate-mediated one-carbon metabolism and neural tube defects in Chinese Han Population.

BACKGROUND: The polymorphism of genes involved in folate-mediated one-carbon metabolism may be a risk factor for neural tube defects (NTDs). In the present study, we aimed to investigate the single nucleotide polymorphisms (SNPs) of the genes BHMT, CUBN, FTCD, GAMT, GART, SARDH, SHMT1, and MUT, and their effect on NTDs in the Chinese Han population. METHODS: A total of 270 NTDs cases and 192 controls were enrolled in this study. The SNPs were analyzed with the next-generation sequencing method. The folate levels of brain tissues from 113 available NTDs cases and 123 available controls were measured. RESULTS: Next-generation sequencing identified 818 single nucleotide variants, including 214 SNPs used for further analysis. Statistical analysis showed that two independent SNP loci, rs2797840 and rs2073817 in SARDH, may be associated with the susceptibility of NTDs. Specifically, the minor allele G of rs2797840 was significantly associated with NTDs risk in spina bifida subgroup (p value = 0.0348). For subjects whose folate content was measured, the protective allele G of rs2797840 was significantly associated with increased folate content of brain. rs2797840 is within several ENCODE regulatory regions, indicating this SNPs may influence expression of SARDH. CONCLUSION: The SNPs rs2797840 and rs2073817 in SARDH may serve as an indicator for the occurrence of NTDs in the Chinese Han population, and rs2797840 may also be an indicator for folate content of brain.

Association between ALDH1L1 gene polymorphism and neural tube defects in the Chinese Han population.

We investigated single-nucleotide polymorphisms (SNPs) in the aldehyde dehydrogenase family1 L1 gene (ALDH1L1) and their association with neural tube defects (NTDs) in the Chinese population. A total of 271 NTDs cases and 192 healthy controls were used in this study. A total of 112 selected SNPs in the ALDH1L1 gene were analyzed using the next-generation sequencing method. Statistical analysis was carried out to investigate the correlation between SNPs and patient susceptibility to NTDs. Statistical analysis revealed a significant correlation between the SNP sites rs4646733, rs2305225, and rs2276731 in the ALDH1L1 gene and NTDs. The TT genotype and T allele of rs4646733 in ALDH1L1 were associated with a significantly increased incidence of NTDs [odds ratio (OR) = 2.16, 95 % confidence interval (CI) 1.199-3.896 for genotype; and OR = 1.46, 95 % CI 1.092-1.971 for allele]. The AA genotype and A allele of rs2305225 in ALDH1L1 were associated with a significantly increased incidence of NTDs (OR = 2.03, 95 % CI 1.202-3.646 for genotype, and OR = 1.44, 95 % CI 1.096-1.905 for allele). The CT genotype and C allele of rs2276731 in ALDH1L1 significantly were associated with an increased incidence of NTDs (OR = 1.67, 95 % CI 1.129-2.491 with genotype, and OR = 1.32, 95 % CI 0.956-1.816 with allele).The polymorphic loci rs4646733, rs2305225, and rs2276731 in the ALDH1L1 gene maybe potential risk factors for NTDs in the Chinese population.

DNA methylation aberrations rather than polymorphisms of FZD3 gene increase the risk of spina bifida in a high-risk region for neural tube defects.

BACKGROUND: Animal models of neural tube defects (NTDs) have indicated roles for the Fzd3 gene and the planar cell polarity signaling pathway in convergent extension. We investigated the involvement of FZD3 in genetic and epigenetic mechanisms associated with human NTDs, especially spina bifida. We explored the effects of variants spanning the FZD3 gene in NTDs and examined the role of aberrant methylation of the FZD3 promoter on gene expression in brain tissue in spina bifida. METHODS: Six FZD3 single nucleotide polymorphisms were genotyped using a MassARRAY system in tissue from 165 NTD fetuses and 152 controls. DNA methylation aberrations in the FZD3 promoter region were detected using a MassARRAY EpiTYPER (17 CpG units from -500 to -2400 bp from the transcription start site) in brain tissue from 77 spina bifida and 74 control fetuses. RESULTS: None of the six single nucleotide polymorphisms evaluated were significantly associated with spina bifida, but the mean methylation level was significantly higher in spina bifida samples (13.70%) compared with control samples (10.91%) (p = 0.001). In terms of specific sites, DNA methylation levels were significantly higher in the spina bifida samples at 14 of the 17 CpG units, which mostly included in R2 region. FZD3 mRNA expression was negatively correlated with methylation of the FZD3 promoter region, especially the R2 region (R = 0.970; p = 0.001) in HeLa cells. CONCLUSION: The results of this study suggest that DNA methylation plays an important role in FZD3 gene expression regulation and may be associated with an increased risk of spina bifida.

Polymorphisms in MTHFD1 Gene and Susceptibility to Neural Tube Defects: A Case-Control Study in a Chinese Han Population with Relatively Low Folate Levels.

BACKGROUND: The polymorphism of methylenetetrahydrofolate dehydrogenase (MTHFD1) has been reported as a risk factor for neural tube defects (NTDs). In the present study, we aimed to investigate whether the single-nucleotide polymorphisms (SNPs) of MTHFD1 gene are associated with NTDs in a Chinese population and to determine their mechanism of action. MATERIAL AND METHODS: MTHFD1 gene was scanned in a total of 270 NTDs cases and 192 healthy controls by using next-generation sequencing (NGS) method. After quality control procedures, 208 selected SNP sites in MTHFD1 gene were enrolled for follow-up statistical association analyses. Functional analyses were also performed for significant SNPs through bioinformatics analysis. Folic acid levels of brain tissue in available NTDs cases and healthy controls (113 and 123, respectively) were measured. Statistical and bioinformatics analyses were performed to investigate the relationship between SNPs in MTHFD1 and susceptibility to NTDs. RESULTS: Statistical analysis showed that 2 independent SNPs, rs1956545 and rs56811449, confer the risk of NTDs (P value=0.0195, OR (odds ratio)=1.41, 95% CI (confidence interval)=1.06-1.88; P value=0.0107, OR=0.56, 95% CI=0.36-0.87). The haplotype GGGG, which consists of 4 SNPs (rs2236225, rs2236224, rs1256146, and rs6573559), is also associated with risk of NTDs (P value=0.0438, OR=0.7180, 95% CI=0.5214-0.9888). The risk allele C of rs1956545 is also associated with decreased folic acid levels in the brain (P value=0.0222, standard beta=-0.2238, 95% CI=-0.4128 - -0.0349) according to analysis in the subset of NTDs cases and healthy controls. Bioinformatics analysis indicates that rs1956545 and rs56811449 are within ENCODE regulatory regions, the open chromatin regions of blastula Trophoblast cell line, and histone-marked region of brain astrocyte cell line. CONCLUSIONS: The polymorphism of SNP loci rs1956545 and rs56811449 as well as a haplotype in MTHFD1 gene could serve as an indicator for the occurrence of NTDs in Chinese population and some specific genotypes of the loci may have lower risk of developing NTDs.

An association study between SUFU gene polymorphisms and neural tube defects.

Neural tube defects (NTDs) in mammals are rooted in aberrant neural tube closure during early embryogenesis, which is caused by multiple environmental and genetic factors. The Sonic Hedgehog pathway is involved in the induction of the floor plate and participates in formation of the neural tube. Mutation of the suppressor of fused gene (SUFU), an essential repressor of Sonic Hedgehog signaling pathway, can result in NTDs. A case-control study was designed to compare the frequencies of the polymorphism at four sites in the SUFU gene in control and NTDs group, as well as in subtype groups, including anencephaly, spina bifida and encephalocele. We also explored the association between polymorphism and NTDs risk in a high prevalence population in China. Rs10786691, but not the other three SNPs, had an association between polymorphisms and NTDs. The heterozygous AG allele of rs10786691 was significantly related with NTDs and encephalocele (OR = 1.60, 95% CI: 1.04-2.48, p = 0.034; OR = 2.83, 95% CI: 1.07-7.47, p = 0.036). In female but not male fetuses, the AG genotype of rs10786691 increased the risk of NTDs (OR = 1.88, 95% CI: 1.03-3.41, p = 0.040). The SUFU rs10786691 A>G polymorphism may be a potential risk factor for NTDs and encephalocele in this high-risk population, but the association between the polymorphism and NTDs was probably influenced by gender.

Histone modification mapping in human brain reveals aberrant expression of histone H3 lysine 79 dimethylation in neural tube defects.

Neural tube defects (NTDs) are severe, common birth defects that result from failure of neural tube closure, but their pathological mechanisms are not yet fully understood. Histone modifications have an important role in gene regulation during fetal development. We therefore hypothesized that the human NTDs may be partly caused by an imbalance in metabolism, perhaps caused by nutritional deficiencies, that leads to aberrant histone modifications. Here, we report a screen of fetal brain histone modifications using 2D nano-LC strong cation exchange reverse phase (SCX/RP) MS/MS and the identification of 61 unique post-translational modification sites on histones H1, H2a, H2b, H3, and H4. Of these, 38 sites are novel (not already found in the Uniprot database). Furthermore, we compared the histone modification patterns between normal brains and NTD brains special of which maternal folate levels were lower than of normal control. The results showed that histone H3 lysine 79 dimethylation (H3K79me2) and a novel identified site, H2bK5 monomethylation (H2bK5me1), were completely absent in individuals with NTDs. Follow-up Western blotting validated the decreased H3K79me2 expression in brains with NTDs, but the amplified samples experiments displayed that decreased H3K79me2 expression was not suitable for all samples with NTDs. Furthermore, folate-free treated mouse embryonic stem cells induced the decreased H3K79me2 level. Subsequently, our ChIP results in normal fetal brain tissues showed that H3K79me2 binds to SUFU, RARA and ITGA3 which induce NTDs phenotype after knockout in mice, and in NTDs brain tissues the bindings of H3K79me2 to these three genes were significantly altered. Taken together, our study indicated that low folate treatment might attenuate H3K79 dimethylation, further affect its regulate activation on target genes, some of which are NTDs-resulting associated, lastly interrupt early embryo developing. Our study increases the understanding of normal fetal brain histone modifications and provides a platform for investigating histone modifications in neural disease and also has an insight into a potential role of aberrant histone modification in etiology of NTDs.

adducin 1 is essential for the survival of erythroid precursors via regulating p53 transcription in zebrafish.

Adducin 1 (Add1) is known as a membrane cytoskeletal protein, but its nuclear function remains unclear. In this study, we generated add1-deficient zebrafish to investigate its role in hematopoiesis. Lack of add1 impaired both primitive and definitive hematopoiesis, preventing healthy erythrocyte development. RNA sequencing revealed activation of the p53 pathway in add1-depleted erythroblast cells, leading to apoptosis at the 14-somites stage and 24 hpf. Interestingly, partial rescue of the anemic phenotype and apoptosis was observed with p53 insufficiency. Mechanistically, ADD1 was found to regulate promoter activity. These findings demonstrate that Add1 plays a crucial role in zebrafish erythropoiesis, involving the p53-mediated apoptotic pathway, expanding its regulatory role beyond cytoskeletal functions.

nkx2.3 is responsible for posterior pharyngeal cartilage formation by inhibiting Fgf signaling.

Nkx2.3, a transcription factor, plays important roles in various developmental processes. However, the mechanisms underlying nkx2.3's regulation of pouch and pharyngeal arch development in zebrafish remain unclear. In this study, we demonstrated that knockdown or knockout of nkx2.3 resulted in the absence of posterior ceratobranchial cartilages in zebrafish. The absence of posterior pharyngeal cartilages is a consequence of the compromised proliferation and differentiation and survival of cranial neural crest cells (CNCCs). Notably, we found that nkx2.3 was not involved in endoderm pouch formation. Additionally, our findings suggested that nkx2.3 negatively regulated Fibroblast growth factor (Fgf) signaling, as overexpression of fgf8 could mimic the phenotype observed in nkx2.3 morphants, suppressing CNCC differentiation. Moreover, inhibiting Fgf signaling restored the abnormalities in posterior cartilages induced by nkx2.3 knockdown. These findings establish the essential role of nkx2.3 in the development of posterior ceratobranchial cartilages through the inhibition of fgf8.

Glutamate carboxypeptidase II gene polymorphisms and neural tube defects in a high-risk Chinese population.

Glutamate carboxypeptidase II (GCPII) catalyzes the hydrolysis of N-acetylaspartylglutamate into N-acetylaspartate and glutamate in the brain. Animal experiments suggested that GCPII plays an essential role in early embryonic development. Previous studies provided conflicting results on the effect of the GCPII rs61886492 C>T (or 1561C>T) polymorphism on NTDs. In the Lvliang area of Shanxi province, where the incidence of NTDs is the highest in China, a case-control study was conducted to investigate possible association between the GCPII rs61886492 and rs202676 polymorphisms and NTD risk. Results indicated all the case and control samples displayed the rs61886492 GG genotype. Although no significant differences in rs202676 genotype or allele frequencies were found between the NTD and control groups, the combined AG+GG genotype group was significantly associated with anencephaly (p = 0.03, OR = 2.11, 95% CI, 1.11-4.01), but not with spina bifida or encephalocele. Overall, the rs202676 A>G polymorphism is a potential risk factor for anencephaly. The results of this study suggest that phenotypic heterogeneity may exist among NTDs in this Chinese population.

Metabolic signature of pregnant women with neural tube defects in offspring.

Neural tube defects (NTDs) are one of the most common types of birth defects, affecting approximately 1 of every 1000 pregnancies in the United States and an estimated 300 000 newborns worldwide each year. The metabolic signature of pregnant women with NTDs in offspring has not previously been characterized. In this paper, we report a profiling study that characterized the serum metabolome of 101 pregnant women affected with NTDs in offspring in comparison with 143 pregnant women with normal pregnancy outcomes in Lvliang prefecture, the area with the highest birth prevalence of NTDs in China. A serum metabonomic study was also conducted to identify significantly altered metabolites associated with di-n-butyl phthalate (DBP)-induced teratogenesis in mice. The metabolic signature of NTD in pregnant women is characterized by the impaired mitochondrial respiration, neurotransmitter γ-aminobutyric acid, and methionine cycle. Of interest, consistent findings from DBP-induced teratogenesis in mice demonstrated increased succinate and decreased fumarate, suggesting an inhibited succinic dehydrogenase implicated in the defective mitochondria. The characteristic disruption of maternal metabolism offers important insights into metabolic mechanisms underlying human NTDs as well as potential preventive strategies.

Intra-family phenotypic heterogeneity of 16p11.2 deletion carriers in a three-generation Chinese family.

The 16p11.2 deletion is a recurrent genomic event and a significant risk factor for autism spectrum disorders (ASD). This genomic disorder also exhibits extensive phenotypic variability and diverse clinical phenotypes. The full extent of phenotypic heterogeneity associated with the 16p11.2 deletion disorder and the factors that modify the clinical phenotypes are currently unknown. Multiplex families with deletion offer unique opportunities for exploring the degree of heterogeneity and implicating modifiers. Here we reported the clinical and genomic characteristics of three 16p11.2 deletion carriers in a Chinese family. The father carries a de novo 16p11.2 deletion, and it was transmitted to the proband and sib. The proband presented with ASD, intellectual disability, learning difficulty, congenital malformations such as atrial septal defect, scoliosis. His dysmorphic features included myopia and strabismus, flat and broad nasal bridge, etc. While the father shared same neurodevelopmental problems as the proband, the younger brother did not show many of the proband's phenotypes. The possible unmasked mutation of TBX6 and MVP gene in this deleted region and the differential distribution of other genomic CNVs were explored to explain the phenotypic heterogeneity in these carriers. This report demonstrated the different developmental trajectory and discordant phenotypes among family members with the same 16p11.2 deletion, thus further illustrated the phenotypic complexity and heterogeneity of the 16p11.2 deletion.

Higher serum homocysteine and lower thyroid hormone levels in pregnant women are associated with neural tube defects.

BACKGROUND: This study tested the hypothesis that abnormal maternal metabolism of both homocysteine and thyroid hormone network in pregnant women is associated with neural tube defects (NTDs) in a part of China with high NTD prevalence. METHODS: A case-control study was performed between 2007 and 2009 in Lüliang Mountains, Shanxi Province. This study included 83 pregnant women who had fetuses with NTDs (cases) and 90 pregnant women with normal fetuses (controls). In addition, a cell model to illustrate the epidemiological findings was established. RESULTS: Fetuses of mother who had both high total homocysteine (tHcy) and inadequate free thyroxine were 3 times more at risk of developing NTDs (adjusted odds ratio = 3.5; 95 % confidence interval = 1.2-10.4; cases vs. controls) using multivariate logistic regression models. Furthermore, biological interaction between metabolisms of Hcy and thyroid hormones was demonstrated in vitro. In homocysteine thiolactone of a metabolite of Hcy-treated mouse embryonic neural stem NE4C cells, genes (Bmp7, Ctnnb1, Notch 1, Gli2, and Rxra) related to both neural tube closure and thyroid hormone network were shown to be regulated by H3K79 homocysteinylation, which increased their expression levels. CONCLUSIONS: The effect of maternal serum high tHcy on risk of developing NTDs is depended on maternal serum level of thyroxine. Meanwhile, a higher level of tHcy might also affect both maternal metabolism of thyroid hormone and neural tube closure in embryogenesis through homocysteinylation of histones.

Aberrant Gcm1 expression mediates Wnt/ß-catenin pathway activation in folate deficiency involved in neural tube defects.

Wnt signaling plays a major role in early neural development. An aberrant activation in Wnt/ß-catenin pathway causes defective anteroposterior patterning, which results in neural tube closure defects (NTDs). Changes in folate metabolism may participate in early embryo fate determination. We have identified that folate deficiency activated Wnt/ß-catenin pathway by upregulating a chorion-specific transcription factor Gcm1. Specifically, folate deficiency promoted formation of the Gcm1/ß-catenin/T-cell factor (TCF4) complex formation to regulate the Wnt targeted gene transactivation through Wnt-responsive elements. Moreover, the transcription factor Nanog upregulated Gcm1 transcription in mESCs under folate deficiency. Lastly, in NTDs mouse models and low-folate NTDs human brain samples, Gcm1 and Wnt/ß-catenin targeted genes related to neural tube closure are specifically overexpressed. These results indicated that low-folate level promoted Wnt/ß-catenin signaling via activating Gcm1, and thus leaded into aberrant vertebrate neural development.