Pathogenesis Of Neural Tube Defects Research Articles

Optical genome mapping identifies rare structural variants in neural tube defects.

Neural tube defects (NTDs) are the most common birth defects of the central nervous system and occur as either isolated malformations or accompanied by anomalies of other systems. The genetic basis of NTDs remains poorly understood using karyotyping, chromosomal microarray, and short-read sequencing, with only a limited number of pathogenic variants identified. Collectively, these technologies may fail to detect rare structural variants (SVs) in the genome, which may cause these birth defects. Therefore, optical genome mapping (OGM) was applied to investigate 104 NTD cases, of which 74 were isolated NTDs and 30 were NTDs with other malformations. A stepwise approach was undertaken to ascertain candidate variants using population and internal databases and performing parental studies when possible. This analysis identifies diagnostic findings in 8% of cases (8/104) and candidate findings in an additional 22% of cases (23/104). Of the candidate findings, 9% of cases (9/104) have SVs impacting genes associated with NTDs in mouse, and 13% of cases (14/104) have SVs impacting genes implicated in the neural tube development pathways. This study identifies RMND5A, HNRNPC, FOXD4, and RBBP4 as strong candidate genes associated with NTDs, and expands the phenotypic spectrum of AMER1 and TGIF1 to include NTDs. This study constitutes the first systematic investigation of SVs using OGM to elucidate the genetic determinants of NTDs. The data provide key insights into the pathogenesis of NTDs and demonstrate the contribution of SVs in the genome to these birth defects.

Exploring Research Trends and Mechanisms: Maternal Diabetes and Neural Tube Defects (1991-2023).

Neural tube defect (NTD) is the second most common congenital neuropathy in the world. Maternal diabetes is an important factor leading to the occurrence of NTD in offspring. However, existing studies lack a systematic analysis of the correlation between maternal diabetes and NTDs, as well as an exploration of NTD pathogenesis and associated preventive strategies. Consequently, there is a need for a thorough examination of the literature pertaining to NTDs and maternal diabetes to elucidate a comprehensive understanding, identify research focal points, and anticipate future developmental trends. The literature related to NTDs and maternal diabetes from 1991 to 2023 was retrieved from the Web of Science Core Collection (WoSCC). Bibliometric software CiteSpace (version 6.2.6) was used for co-occurrence/citation network analysis and to draw a knowledge visualization map. A total of 382 articles and reviews were included in the final analysis. Findings revealed an increasing trend in annual publication rates. The University of Maryland Baltimore emerged as the institution with the highest number of publications, while the American Journal of Obstetrics and Gynecology and Birth Defects Research Part A-Clinical and Molecular Teratology stood out as the most prolific research journals. EA Reece was identified as the leading contributor in this domain. The United States emerged as the global leader in this field, making the most significant contribution to research endeavors. The cluster analysis of keywords obtained eight clusters, and the research focus was on the pathogenesis of NTDs induced by maternal diabetes. This study employed bibliometric methods to visualize the research landscape of NTDs induced by maternal diabetes, aiming to comprehend trends and identify key areas of interest in this domain. By studying the relevant mechanisms, we will search for new key targets. Meanwhile, future research needs to further explore new treatment strategies.

ApoM maintains cellular homeostasis between mitophagy and apoptosis by affecting the stability of Nnt mRNA through the Zic3-ApoM-Elavl2-Nnt axis during neural tube closure

Research on the aetiology of neural tube defects (NTDs) has made progress in recent years. However, the molecular mechanism of apolipoproteins underlying NTDs development remains unclear. This study aimed to investigate the function of apolipoprotein M (ApoM) in the pathogenesis of NTDs and its underlying mechanisms. We demonstrated that ApoM expression was reduced in the spinal cord samples of rat models and human fetuses with NTDs respectively. Specifically, lack of ApoM resulted in reduced cytosolic localization of Elavl2 and caused Nnt mRNA degradation, which further led to impaired cell homeostasis by suppressing PINK1-PRKN-mediated mitophagy and promoting apoptosis and subsequent NTDs formation. Moreover, Zic3 directly interacted with the promoter of ApoM and activated its transcription. Lastly, intra-amniotic delivery of adenoviral recombinant Zic3 or ApoM could promote mitophagy and alleviate apoptosis in spinal cords of NTDs. Collectively, these findings highlight the important role of the Zic3-ApoM-Elavl2-Nnt axis in cellular homeostasis during neural tube development, thereby revealing an intracellular molecular regulatory mechanism of ApoM, providing a mechanistic basis for understanding embryonic neural development, and offering experimental evidence for potential therapeutic targets for NTDs.

Characterization of CircRNA-Associated CeRNA Networks in Folate Deficiency-Induced Neural Tube Defects

Characterization of CircRNA-Associated CeRNA Networks in Folate Deficiency-Induced Neural Tube Defects

MicroRNA-Mediated Regulation of BMP Signaling in the Developing Neural Tube.

Neural tube (NT) morphogenesis is reliant on the proper temporospatial expression of numerous genes and synchronized crosstalk between diverse signaling cascades and gene regulatory networks governing key cellular processes. MicroRNAs (miRNAs), a group of small non-coding regulatory RNAs, execute defining roles in directing key canonical pathways during embryogenesis. In order to comprehend the mechanistic underpinnings of miRNA regulation of NT morphogenesis, we have identified in the current study various miRNAs and their target mRNAs associated with BMP signaling during critical stages of neurulation. We previously demonstrated the expression of several miRNAs during the critical stages of neurulation (gestational days (GD) 8.5, 9.0, and 9.5) employing high-sensitivity, high-coverage microarrays. In the present study, bioinformatic analyses were used to identify miRNAs differentially expressed (DE) in the embryonic NT that target messenger RNAs (mRNAs) associated with the bone morphogenetic protein (BMP) signaling pathway. RNAs extracted from the developing NT were hybridized to both miRNA and mRNA arrays to evaluate miRNA-mRNA interactions. Bioinformatic analysis identified several DE miRNAs that targeted mRNAs encoding members of (and proteins associated with) the BMP signaling pathway - a signaling cascade central to normal NT development. Identification of the miRNAs and their mRNA targets associated with BMP signaling facilitates a better understanding of the crucial epigenetic mechanisms underlying normal NT development as well as the pathogenesis of NT defects. The current study supports the notion that miRNAs function as key regulators of neural tube morphogenesis via modulation of the BMP signaling cascade. Altered expression of these miRNAs during neurulation may therefore result in NT defects.

Administration of prosaposin-derived neurotrophic factor to neural tube defects facilitates regeneration and restores neurological functions

Administration of prosaposin-derived neurotrophic factor to neural tube defects facilitates regeneration and restores neurological functions

Neural Tube Defects and Folate Deficiency: Is DNA Repair Defective?

Neural tube defects (NTDs) are complex congenital malformations resulting from failure of neural tube closure during embryogenesis, which is affected by the interaction of genetic and environmental factors. It is well known that folate deficiency increases the incidence of NTDs; however, the underlying mechanism remains unclear. Folate deficiency not only causes DNA hypomethylation, but also blocks the synthesis of 2'-deoxythymidine-5'-monophosphate (dTMP) and increases uracil misincorporation, resulting in genomic instabilities such as base mismatch, DNA breakage, and even chromosome aberration. DNA repair pathways are essential for ensuring normal DNA synthesis, genomic stability and integrity during embryonic neural development. Genomic instability or lack of DNA repair has been implicated in risk of development of NTDs. Here, we reviewed the relationship between folate deficiency, DNA repair pathways and NTDs so as to reveal the role and significance of DNA repair system in the pathogenesis of NTDs and better understand the pathogenesis of NTDs.

Abnormal methylation caused by folic acid deficiency in neural tube defects.

Neural tube closure disorders, including anencephaly, spina bifida, and encephalocele, cause neural tube defects (NTDs). This congenital disability remained not only a major contributor to the prevalence of stillbirths and neonatal deaths but also a significant cause of lifelong physical disability in surviving infants. NTDs are complex diseases caused by multiple etiologies, levels, and mechanisms. Currently, the pathogenesis of NTDs is considered to be associated with both genetic and environmental factors. Here, we aimed to review the research progress on the etiology and mechanism of NTDs induced by methylation modification caused by folic acid deficiency. Folic acid supplementation in the diet is reported to be beneficial in preventing NTDs. Methylation modification is one of the most important epigenetic modifications crucial for brain neurodevelopment. Disturbances in folic acid metabolism and decreased S-adenosylmethionine levels lead to reduced methyl donors and methylation modification disorders. In this review, we summarized the relationship between NTDs, folic acid metabolism, and related methylation of DNA, imprinted genes, cytoskeletal protein, histone, RNA, and non-coding RNA, so as to clarify the role of folic acid and methylation in NTDs and to better understand the various pathogenesis mechanisms of NTDs and the effective prevention.

Loss-of-Function of p21-Activated Kinase 2 Links BMP Signaling to Neural Tube Patterning Defects.

Closure of the neural tube represents a highly complex and coordinated process, the failure of which constitutes common birth defects. The serine/threonine kinase p21-activated kinase 2 (PAK2) is a critical regulator of cytoskeleton dynamics; however, its role in the neurulation and pathogenesis of neural tube defects (NTDs) remains unclear. Here, the results show that Pak2-/- mouse embryos fail to develop dorsolateral hinge points (DLHPs) and exhibit craniorachischisis, a severe phenotype of NTDs. Pak2 knockout activates BMP signaling that involves in vertebrate bone formation. Single-cell transcriptomes reveal abnormal differentiation trajectories and transcriptional events in Pak2-/- mouse embryos during neural tube development. Two nonsynonymous and one recurrent splice-site mutations in the PAK2 gene are identified in five human NTD fetuses, which exhibit attenuated PAK2 expression and upregulated BMP signaling in the brain. Mechanistically, PAK2 regulates Smad9 phosphorylation to inhibit BMP signaling and ultimately induce DLHP formation. Depletion of pak2a in zebrafish induces defects in the neural tube, which are partially rescued by the overexpression of wild-type, but not mutant PAK2. The findings demonstrate the conserved role of PAK2 in neurulation in multiple vertebrate species, highlighting the molecular pathogenesis of PAK2 mutations in NTDs.

Single nucleotide polymorphisms of PCP pathway related genes participate in the occurrence and development of neural tube defect.

To screen the single nucleotide polymorphisms (SNPs) in the coding regions of VANGL and FZD family members related to the plane cell polarity (PCP) signaling pathway in neural tube defects (NTDs) patients, so as to provide theoretical and experimental basis for the prevention and treatment of NTDs by intervening PCP signal transduction. 112 NTDs patients were collected as the case group and 112 craniocerebral trauma patients as control. Afterwards, blood genomic DNA was extracted and sequenced. The distribution of SNP alleles and genotypes between case and control groups was analyzed. Finally, the NTD rat model was constructed, and the effect of SNPs on the expression level of VANGL and FZD genes was verified by qRT-PCR. GC genotype was newly found at VANGL1 c.346G>A, as well as AT genotype in FZD6 c.97A>G. The distribution of VANGL1 c.346g>A allele and genotype was statistically different between the case and control groups (p < 0.05). The newly found genotype GC increased the risk of NTDs (OR=9.918, 95% CI: 1.234%-79.709%). The results of qRT-PCR showed that the expression level of FZD6 in E11 NTD fetuses were significantly increased (p < 0.05), but there was no obvious difference in the expression of VANGL1. We found a new variant of VANGL1 c.346G>A, whose GC genotype might play an important role in the pathogenesis of NTDs. The SNPs of VANGL1 had no significant effect on its expression level, indicating that it may induce NTDs through other ways. FZD6 was significantly overexpressed in NTDs fetuses.

Upregulation of miRNA-26a Enhances the Apoptosis of Cerebral Neurons by Targeting EphA2 and Inhibiting the MAPK Pathway

Neural tube defects (NTDs) constitute the second most common congenital malformation of the central nervous system. The pathogenesis of NTDs is not entirely clear. In recent years, microRNAs (miRNAs) have become a hot spot in genetic and developmental biology research. The present study aimed to explore the potential role of miRNA-26a in NTDs and the underlying pathogenesis thereof. First, we found significantly increased miRNA-26a expression in fetuses with NTDs (p < 0.0001), which significantly downregulated EphA2 and ERK1 mRNA and protein expression levels in fetuses with NTDs compared to normal controls (p < 0.01). In addition, a dual-luciferase reporter assay showed that miR-26a negatively regulated EphA2 by directly binding with the 3′-untranslated region of EphA2. Second, the upregulation of miRNA-26a expression increased caspase 3 and 9 protein expression levels (p < 0.01) and decreased EphA2 mRNA and protein expression levels (p < 0.01), as well as ERK1 and SRF protein expression levels (p < 0.01) in mouse neural stem cells (NE-4C) and human astroblastoma cells (U87MG). Furthermore, the upregulation of miRNA-26a inhibited cell proliferation and enhanced apoptosis of NE-4C and U87MG cells (p < 0.05). Similar results were observed with the MAPK inhibitor PD98059 (p < 0.01). These results suggest that miR-26a targets EphA2, modulates phosphorylation of the MAPK/ERK (MEK) pathway, regulates SRF, and participates in regulating nervous cell proliferation and apoptosis. Dysregulation of the aforementioned mechanism may be involved in the pathogenesis of NTDs.

Exploring epigenomic mechanisms of neural tube defects using multi-omics methods and data.

Neural tube defects (NTDs) are a heterogeneous set of malformations attributed to disruption in normal neural tube closure during early embryogenesis. An in-depth understanding of NTD etiology and mechanisms remains elusive, however. Among the proposed mechanisms, epigenetic changes are thought to play an important role in the formation of NTDs. Epigenomics covers a wide spectrum of genomic DNA sequence modifications that can be investigated via high-throughput techniques. Recent advances in epigenomic technologies have enabled epigenetic studies of congenital malformations and facilitated the integration of big data into the understanding of NTDs. Herein, we review clinical epigenomic data that focuses on DNA methylation, histone modification, and miRNA alterations in human neural tissues, placental tissues, and leukocytes to explore potential mechanisms by which candidate genes affect human NTD pathogenesis. We discuss the links between epigenomics and gene regulatory mechanisms, and the effects of epigenetic alterations in human tissues on neural tube closure.

Pathogenesis of neural tube defects: The regulation and disruption of cellular processes underlying neural tube closure.

Neural tube closure (NTC) is crucial for proper development of the brain and spinal cord and requires precise morphogenesis from a sheet of cells to an intact three-dimensional structure. NTC is dependent on successful regulation of hundreds of genes, a myriad of signaling pathways, concentration gradients, and is influenced by epigenetic and environmental cues. Failure of NTC is termed a neural tube defect (NTD) and is a leading class of congenital defects in the United States and worldwide. Though NTDs are all defined as incomplete closure of the neural tube, the pathogenesis of an NTD determines the type, severity, positioning, and accompanying phenotypes. In this review, we survey pathogenesis of NTDs relating to disruption of cellular processes arising from genetic mutations, altered epigenetic regulation, and environmental influences by micronutrients and maternal condition. This article is categorized under: Congenital Diseases > Genetics/Genomics/Epigenetics Neurological Diseases > Genetics/Genomics/Epigenetics Neurological Diseases > Stem Cells and Development.

Identification of immune-related biomarkers in embryos with neural tube defects via a bioinformatics analysis.

BackgroundNeural tube defects (NTDs) are one of the most common types of birth defects. Oral folic acid (FA) prophylaxis is currently available, but the pathogenesis of NTDs is not fully understood. We conducted this study to examine the role of the immune landscape of NTDs and identify novel diagnostic and therapeutic biomarkers.MethodsWe downloaded the GSE33111 data set of 12 NTD embryos and 12 healthy embryos in the same period of fetal development from the Gene Expression Omnibus (GEO) database. We compared the healthy embryos and NTD embryos to identify the differentially expressed genes (DEGs). We also performed a functional enrichment analysis of the DEGs using the clusterProfiler package. We extracted the top 10 ranked genes as hub immune-related biomarkers. We then used receiver operating characteristic (ROC) curves to determine the expression levels of the hub immune-related genes and the accuracy of the diagnosis of NTDs. Finally, we analyzed the immune landscape of the NTD embryos and healthy embryos via a single-sample gene set enrichment analysis (ssGSEA).ResultsA total of 611 DEGs were identified by the differential analysis, including 95 immune genes. The functional enrichment analysis indicated that Epstein-Barr virus infection, antigen processing and presentation, inflammatory bowel disease, and type I diabetes mellitus were associated with NTDs. The results of the expression level analysis showed that the hub immune-related genes were more highly expressed in the NTD embryos than the healthy embryos. Additionally, the ROC curve analysis also indicated that the expression levels of the 10 hub immune-related genes were highly accurate in the diagnosis of NTDs [area under the curve (AUC) range, 0.708–0.812]. The immune infiltration analysis demonstrated that 20 of the 28 immune cell types were more highly infiltrated in the NTD embryos than the healthy embryos.ConclusionsImmune-related genes are important regulators of the occurrence and development of NTDs.

Nuclear factor I-C disrupts cellular homeostasis between autophagy and apoptosis via miR-200b-Ambra1 in neural tube defects

Impaired autophagy and excessive apoptosis disrupt cellular homeostasis and contribute to neural tube defects (NTDs), which are a group of fatal and disabling birth defects caused by the failure of neural tube closure during early embryonic development. However, the regulatory mechanisms underlying NTDs and outcomes remain elusive. Here, we report the role of the transcription factor nuclear factor I-C (NFIC) in maintaining cellular homeostasis in NTDs. We demonstrated that abnormally elevated levels of NFIC in a mouse model of NTDs can interact with the miR-200b promoter, leading to the activation of the transcription of miR-200b, which plays a critical role in NTD formation, as reported in our previous study. Furthermore, miR-200b represses autophagy and triggers apoptosis by directly targeting the autophagy-related gene Ambra1 (Autophagy/Beclin1 regulator 1). Notably, miR-200b inhibitors mitigate the unexpected effects of NFIC on autophagy and apoptosis. Collectively, these results indicate that the NFIC-miR-200b-Ambra1 axis, which integrates transcription- and epigenome-regulated miRNAs and an autophagy regulator, disrupts cellular homeostasis during the closure of the neural tube, and may provide new insight into NTD pathogenesis.

Bhlhe40/Sirt1 Axis-Regulated Mitophagy Is Implicated in All-Trans Retinoic Acid-Induced Spina Bifida Aperta.

Neural tube defects (NTDs) 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. Mitophagy is the best-known way of mitochondrial quality control. However, the role and regulation of mitophagy in NTDs have not yet been elucidated. In this study, we used an all-trans retinoic acid (ATRA)-induced rat model to investigate mitophagy and its underlying mechanism in spina bifida aperta (SBA). The results of western blot, immunofluorescence and RT-qPCR analyses indicated that mitophagy was impaired and Sirt1 was downregulated in SBA. Administration of resveratrol-a strong specific Sirt1 activator-activated Sirt1, thus attenuating autophagy suppression and ameliorating SBA. RNA-sequencing and bioinformatics analysis results indicated that transcriptional regulation played an important role in NTDs. A luciferase reporter assay was performed to demonstrate that the transcription factor Bhlhe40 directly bound to and negatively regulated Sirt1 expression. Further, we discovered that the Bhlhe40/Sirt1 axis regulated mitophagy in neural stem cells. Collectively, our results for the first time demonstrate that Bhlhe40/Sirt1 axis regulated mitophagy is implicated in ATRA-induced SBA. Our findings provide new insights into pathogenesis of NTDs and a basis for potential therapeutic targets for NTDs.

Organoids as a new model system to study neural tube defects.

The neural tube is the first critically important structure that develops in the embryo. It serves as the primordium of the central nervous system; therefore, the proper formation of the neural tube is essential to the developing organism. Neural tube defects (NTDs) are severe congenital defects caused by failed neural tube closure during early embryogenesis. The pathogenesis of NTDs is complicated and still not fully understood even after decades of research. While it is an ethically impossible proposition to investigate the in vivo formation process of the neural tube in human embryos, a newly developed technology involving the creation of neural tube organoids serves as an excellent model system with which to study human neural tube formation and the occurrence of NTDs. Herein we reviewed the recent literature on the process of neural tube formation, the progress of NTDs investigations, and particularly the exciting potential to use neural tube organoids to model the cellular and molecular mechanisms underlying the etiology of NTDs.

Spatiotemporal expression of leukemia inhibitory factor receptor protein during neural tube development in embryos with neural tube defects.

Leukemia inhibitory factor receptor (LIFR), as a neuroregulatory cytokine receptor, generally shows a neuroprotective effect in central nervous system injuries. In this study, to understand the effect of LIFR on pathogenesis of neural tube defects, we explored spatiotemporal expression of LIFR at different stages of fetal development in normal and neural tube defect embryos. Spina bifida aperta was induced with all-trans retinoic acid on embryonic day 10 in rats, and the spatiotemporal expression of LIFR was investigated in spina bifida aperta rats and healthy rats from embryonic day 11 to 17. Real time-polymerase chain reaction and western blot assay were used to examine mRNA and protein expression of LIFR in healthy control and neural tube defect embryos. Results of the animal experiment demonstrated that expression of LIFR protein and mRNA in the spinal cords of normal rat embryos increased with embryonic development. LIFR was significantly downregulated in the spinal cords of spina bifida aperta rats compared with healthy rats from embryonic days 11 to 17. Immunohistochemical staining showed that the expression of LIFR in placenta and spinal cord in spina bifida aperta rat embryos was decreased compared with that in control embryos at embryonic day 15. Results from human embryo specimens showed that LIFR mRNA expression was significantly down-regulated in spinal cords of human fetuses with neural tube defects compared with normal controls at a gestational age of 24 to 33 weeks. The results were consistent with the down-regulation of LIFR in the animal experiments. Our study revealed spatiotemporal changes in expression of LIFR during embryonic neurulation. Thus, LIFR might play a specific role in neural tube development. All animal and human experimental procedures were approved by the Medical Ethics Committee of Shengjing Hospital of China Medical University, China (approval No. 2016PS106K) on February 25, 2016.

Why is folate effective in preventing neural tube closure defects?

Why is folate effective in preventing neural tube closure defects?

Update on the Role of the Non-Canonical Wnt/Planar Cell Polarity Pathway in Neural Tube Defects.

Neural tube defects (NTDs), including spina bifida and anencephaly, represent the most severe and common malformations of the central nervous system affecting 0.7–3 per 1000 live births. They result from the failure of neural tube closure during the first few weeks of pregnancy. They have a complex etiology that implicate a large number of genetic and environmental factors that remain largely undetermined. Extensive studies in vertebrate models have strongly implicated the non-canonical Wnt/planar cell polarity (PCP) signaling pathway in the pathogenesis of NTDs. The defects in this pathway lead to a defective convergent extension that is a major morphogenetic process essential for neural tube elongation and subsequent closure. A large number of genetic studies in human NTDs have demonstrated an important role of PCP signaling in their etiology. However, the relative contribution of this pathway to this complex etiology awaits a better picture of the complete genetic architecture of these defects. The emergence of new genome technologies and bioinformatics pipelines, complemented with the powerful tool of animal models for variant interpretation as well as significant collaborative efforts, will help to dissect the complex genetics of NTDs. The ultimate goal is to develop better preventive and counseling strategies for families affected by these devastating conditions.