Diabetes and apoptosis: neural crest cells and neural tube

Wnt/BMP Mediated Metabolic Reprogramming Preserves Multipotency of Neural Crest-Like Stem Cells

Neural crest-like stem cells resembling embryonic neural crest cells (NCs) can be derived from adult human tissues such as the epidermis. However, these cells lose their multipotency rapidly in culture limiting their expansion for clinical use. Here, we show that the multipotency of keratinocyte-derived NCs (KC-NCs) can be preserved by activating the Wnt and BMP signaling axis, promoting expression of key NC-specifier genes and ultimately enhancing their differentiation potential. We also show that transcriptional changes leading to multipotency are linked to metabolic reprogramming of KC-NCs to a highly glycolytic state. Specifically, KC-NCs treated with CHIR and BMP2 rely almost exclusively on glycolysis for their energy needs, as seen by increased lactate production, glucose uptake, and glycolytic enzyme activities. This was accompanied by mitochondrial depolarization and decreased mitochondrial ATP production. Interestingly, the glycolytic end-product lactate stabilized β-catenin and further augmented NC-gene expression. Taken together, our study shows that activation of the Wnt/BMP signaling coordinates the metabolic demands of neural crest-like stem cells governing decisions regarding multipotency and differentiation, with possible implications for regenerative medicine.

Unusual occurrence of domestication syndrome amongst African mole-rats: Is the naked mole-rat a domestic animal?

The Naked mole-rat (NMR) is becoming a prominent model organism due to its peculiar traits, such as eusociality, extreme longevity, cancer resistance, and reduced pain sensitivity. It belongs to the African mole-rats (AMR), a family of subterranean rodents that includes solitary, cooperative breeding and eusocial species. We identified and quantified the domestication syndrome (DS) across AMR, a set of morphological and behavioural traits significantly more common and pronounced amongst domesticated animals than in their wild counterparts. Surprisingly, the NMR shows apparent DS traits when compared to the solitary AMR. Animals can self-domesticate when a reduction of the fear response is naturally selected, such as in islands with no predators, or to improve the group’s harmony in cooperative breeding species. The DS may be caused by alterations in the physiology of the neural crest cells (NCC), a transient population of cells that generate a full range of tissues during development. The NCC contribute to organs responsible for transmitting the fear response and various other tissues, including craniofacial bones. Therefore, mutations affecting the NCC can manifest as behavioural and morphological alterations in many structures across the body, as seen in neurocristopathies. We observed that all social AMRs are chisel-tooth diggers, an adaption to hard soils that requires the flattening of the skull. We hypothesise that chisel-tooth digging could impose a selective pressure on the NCC that triggered the DS’s appearance, possibly facilitating the evolution of sociality. Finally, we discuss how DS traits are neutral or beneficial for the subterranean niche, strategies to test this hypothesis and report well-studied mutations in the NMR that are associated with the NCC physiology or with the control of the fear response. In conclusion, we argue that many of the NMR’s unconventional traits are compatible with the DS and provide a hypothesis about its origins. Our model proposes a novel avenue to enhance the understanding of the extraordinary biology of the NMR.

Synergistic Effects of Folic Acid and n-3 Polyunsaturated Fatty Acid in Preventing Neural Tube Defects in Diabetic Mice

The present study aimed to investigate whether a combination of folic acid (FA) and n-3 polyunsaturated fatty acids (PUFA) has a better preventive effect on maternal diabetes-induced neural tube defects (NTD) than FA alone. The experiment included five groups of pregnant mice: healthy control (HC), diabetes mellitus control (DMC), diabetes + n-3 PUFA (DMn-3), diabetes + FA (DMFA), and diabetes + FA + n-3 PUFA (DMFA + n-3). The incidence of NTD in DMFA + n-3 (1.04%) was significantly lower than that in DMFA (8.57%) and DMn-3 (7.82%). The incidence of NTD in DMFA and DMn-3 was significantly lower than that in DMC (19.41%). DMFA + n-3 had a lower apoptosis of neuroepithelial cells, a lower expression of P53 and Bax, and a higher expression of Pax3 and Bcl-2, compared with DMFA and DMn-3. Combination of FA and n-3 PUFA attenuated diabetes-induced hypermethylation of Pax3, overexpression and overactivity of Dnmt3b, abnormal expression of genes involved in one-carbon metabolism and elevation of homocysteine, and these improving effects were better than FA or n-3 PUFA alone. In conclusion, the combination of FA and n-3 PUFA has a synergistic effect on preventing maternal diabetes-induced NTD.

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.

High concentrations of aluminum in maternal serum and placental tissue are associated with increased risk for fetal neural tube defects

Aluminum (Al)¹ is ubiquitously present in the environment, and human exposure to Al is common. Al has been reported to be involved in various human diseases and adverse pregnancy outcomes, including neural tube defects (NTDs). This study aimed to examine the association between prenatal Al exposure and the risk for NTDs using Al concentrations in maternal serum and placental tissue. The subjects were recruited from six counties/cities in the Shanxi province of northern China from 2003 to 2016. Al concentrations in both types of specimens were assessed using inductively coupled plasma-mass spectrometry. In the maternal serum cohort (200 cases and 400 controls), compared to the lowest tertile concentration of Al, the highest Al tertile was associated with 2.42-fold (95% confidence interval, 1.23-4.87) increased risk after adjustment for confounding factors. In the placental tissue cohort (408 cases and 593 controls), the highest tertile of Al also tended to be associated with an elevated risk for NTDs [adjusted odds ratio, 1.60 (0.94-2.70)]. When analyzed by NTD subtypes, the highest Al tertile was associated with an increased risk for anencephaly in both cohorts after adjustment for confounders [odds ratio, 1.97 (1.15-3.48) in the maternal serum cohort; odds ratio, 4.75 (2.01-12.00) in the placental tissue cohort]. Taken together, using concentrations of Al in maternal serum and placental tissue as exposure markers, we found that prenatal exposure to higher levels of Al is a risk factor for fetal NTDs, especially for the anencephaly subtype.

N-3 polyunsaturated fatty acids effectively protect against neural tube defects in diabetic mice induced by streptozotocin

Folate cannot prevent all neural tube defects (NTD), indicating that other pathogeneses still exist except for the folate deficiency. Maternal diabetes mellitus during pregnancy can increase the risk of offspring NTD. Our previous study showed that polyunsaturated fatty acids (PUFA) were lower in the placenta of human NTD cases than in healthy controls, and the supplementation of fish oil (rich in long-chain (LC) n-3 PUFA, mainly C20:5n-3 and C22:6n-3) had a better prevention effect against sodium valproate induced NTD than corn oil (rich in C18:2n-6) and flaxseed oil (rich in C18:3n-3). The aim of the present study was to investigate whether PUFA could prevent diabetes-induced NTD in mice. Streptozotocin (STZ)-induced diabetic pregnant mice were fed with a normal diet (DMC), a diet containing a low dose of fish oil (DMLn-3), a diet containing a high dose of fish oil (DMHn-3) or a diet rich in corn oil (DMn-6). Healthy pregnant mice were fed with a normal diet (HC). Compared with the DMC group, the rate of NTD was significantly lower in the DMHn-3 group (4.44% vs. 12.50%), but not in the DMLn-3 (11.11%) or DMn-6 group (12.03%). The NTD rate in the DMHn-3 group was comparable with that in the HC group (1.33%) (p = 0.246), and lower than that in the DMn-6 group (p = 0.052). The NTD rate in DMLn-3 and DMn-6 groups was significantly higher than that in the HC group. No significant difference was observed in NTD rate between DMLn-3 and DMHn-3 groups, and between DMLn-3 and DMn-6 groups. Compared with the HC group, the DMC group had a significantly lower C22:6n-3 in both serum and embryos. Fish oil supplementation ameliorated neuroepithelial cell apoptosis, and the apoptotic rate was comparable between DMHn-3 and HC groups. Although the apoptotic rate was significantly lower in the DMn-6 group than the DMC group, it was still much higher than that in the HC group. The proteins P53 and Bax in embryos were higher, while the proteins Bcl-2 and Pax3 were lower in the DMC group than in the HC group. The disturbance of Pax3, P53 and Bax induced by diabetes was abolished in DMLn-3, DMHn-3 and DMn-6 groups. Importantly, Bcl-2 in embryos was restored to the normal level only in the DMHn-3 group but not in the DMLn-3 or DMn-6 group. In conclusion, LC n-3 PUFA enriched fish oil has a protective effect against NTD in diabetes induced by STZ through improving neuroepithelial cell apoptosis, and the mechanism may be by increasing the anti-apoptosis protein Bcl-2 independently of Pax3 and P53.

Neural crest metabolism: At the crossroads of development and disease

The neural crest is a migratory stem cell population that contributes to various tissues and organs during vertebrate embryonic development. These cells possess remarkable developmental plasticity and give rise to many different cell types, including chondrocytes, osteocytes, peripheral neurons, glia, melanocytes, and smooth muscle cells. Although the genetic mechanisms underlying neural crest development have been extensively studied, many facets of this process remain unexplored. One key aspect of cellular physiology that has gained prominence in the context of embryonic development is metabolic regulation. Recent discoveries in neural crest biology suggest that metabolic regulation may play a central role in the formation, migration, and differentiation of these cells. This possibility is further supported by clinical studies that have demonstrated a high prevalence of neural crest anomalies in babies with congenital metabolic disorders. Here, we examine why neural crest development is prone to metabolic disruption and discuss how carbon metabolism regulates developmental processes like epithelial-to-mesenchymal transition (EMT) and cell migration. Finally, we explore how understanding neural crest metabolism may inform upon the etiology of several congenital birth defects.

Diabetes, Oxidative Stress, and DNA Damage Modulate Cranial Neural Crest Cell Development and the Phenotype Variability of Craniofacial Disorders

Craniofacial malformations are among the most common birth defects in humans and they often have significant detrimental functional, aesthetic, and social consequences. To date, more than 700 distinct craniofacial disorders have been described. However, the genetic, environmental, and developmental origins of most of these conditions remain to be determined. This gap in our knowledge is hampered in part by the tremendous phenotypic diversity evident in craniofacial syndromes but is also due to our limited understanding of the signals and mechanisms governing normal craniofacial development and variation. The principles of Mendelian inheritance have uncovered the etiology of relatively few complex craniofacial traits and consequently, the variability of craniofacial syndromes and phenotypes both within families and between families is often attributed to variable gene expression and incomplete penetrance. However, it is becoming increasingly apparent that phenotypic variation is often the result of combinatorial genetic and non-genetic factors. Major non-genetic factors include environmental effectors such as pregestational maternal diabetes, which is well-known to increase the risk of craniofacial birth defects. The hyperglycemia characteristic of diabetes causes oxidative stress which in turn can result in genotoxic stress, DNA damage, metabolic alterations, and subsequently perturbed embryogenesis. In this review we explore the importance of gene-environment associations involving diabetes, oxidative stress, and DNA damage during cranial neural crest cell development, which may underpin the phenotypic variability observed in specific craniofacial syndromes.

Treatment and Prevention of Neurocristopathies

Neurocristopathies form a heterogeneous group of rare diseases caused by abnormal development of neural crest cells. Heterogeneity of neurocristopathies directly relates to the nature of these migratory and multipotent cells, which generate dozens of specialized cell types throughout the body. Neurocristopathies are thus characterized by congenital malformations of tissues/organs that otherwise appear to have very little in common, such as the craniofacial skeleton and enteric nervous system. Treatment options are currently very limited, mainly consisting of corrective surgeries. Yet, as reviewed here, analyses of normal and pathological neural crest development in model organisms have opened up the possibility for better treatment options involving cellular and molecular approaches. These approaches provide hope that some neurocristopathies might soon be curable or preventable.

Deficiency of the oxidative stress-responsive kinase p70S6K1 restores autophagy and ameliorates neural tube defects in diabetic embryopathy

BACKGROUND

Autophagy is highly active in neuroepithelial cells of the developing neuroepithelium, and impairment of autophagy leads to neural tube defects. In this study, we have found that maternal diabetes suppresses autophagy that leads to neural tube defects and consequent cellular imbalance in the endoplasmic reticulum where critical events occur, leading to the induction of diabetic embryopathy. Because the mammalian target of rapamycin pathway suppresses autophagy, we hypothesized that 70 kDa ribosomal protein S6 kinase 1 (p70S6K1), a major downstream effector of mammalian target of rapamycin, mediates the inhibitory effect of maternal diabetes on autophagy in the developing neuroepithelium.

OBJECTIVE

We investigated whether p70S6K1 mediates the inhibitory effect of maternal diabetes on autophagy during neurulation. We also examined whether p70S6K1 deficiency restores autophagy and therefore relieves endoplasmic reticulum stress and inhibits maternal diabetes-induced apoptosis, which leads to reduction in neural tube defect incidence in diabetic embryopathy.

STUDY DESIGN

Female p70S6K1 heterogeneous knockout (p70S6K1+/-) mice were bred with male p70S6K1 heterogeneous knockout (p70S6K1+/-) mice to generate wild-type (WT), p70S6K1+/- and p70S6K1 knockout (p70S6K1-/-) embryos. Embryos at embryonic day 8.5 were harvested for the assessment of indices of autophagy, endoplasmic reticulum stress, and apoptosis. Neural tube defect incidence in embryos was determined at embryonic day 10.5. For in vitro studies, small interfering RNA knockdown of p70S6K1 in C17.2 mouse neural stem cells was used to determine the effect of p70S6K1 deficiency on autophagy impairment and endoplasmic reticulum stress under high glucose conditions.

RESULTS

Knockout of the Rps6kb1 gene, which encodes for p70S6K1, ameliorated maternal diabetes-induced NTDs and restored autophagosome formation in neuroepithelial cells suppressed by maternal diabetes. Maternal diabetes-suppressed conversion of LC3-I (microtubule-associated protein 1A/1B-light chain 3) to LC3-II, an index of autophagic activity, in neurulation stage embryos was abrogated in the absence of p70S6K1. p70S6K1 knockdown in neural stem cells also restored autophagosome formation and the conversion of LC3-I to LC3-II. The activation of the major unfolded protein response, indicated by phosphorylation of inositol-requiring enzyme 1 alpha, and protein kinase R-like endoplasmic reticulum kinase, and eukaryotic translation initiation factor 2α, and the increase of the endoplasmic reticulum stress marker, C/EBP homologous protein, were induced by maternal diabetes in vivo and high glucose in vitro. Unfolded protein response and endoplasmic reticulum stress induced by maternal diabetes or high glucose were reduced by Rps6kb1 deletion or p70S6K1 knockdown, respectively. Rps6kb1 knockout blocked maternal diabetes-induced caspase cleavage and neuroepithelial cell apoptosis. The superoxide dismutase mimetic Tempol abolished high glucose-induced p70S6K1 activation.

CONCLUSION

The study revealed the critical involvement of p70S6K1 in the pathogenesis of diabetic embryopathy.

Nano-sulforaphane attenuates PhIP-induced early abnormal embryonic neuro-development

BACKGROUND

2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyrimidine (PhIP), one of the most abundant heterocyclic aromatic amines (HAA) formed by cooking meat at high temperatures, may modify humans and rodents through the metabolic process prior to affecting nervous system development. In humans and rodents may be modified by metabolic processes and then affecting nervous system development.

METHODS

In this paper, PhIP was used to prepare a chicken embryo model with abnormal embryonic nervous system defects. Sulforaphane (SFN) is a derivative of a glucosinolate, which is abundant in cruciferous vegetables, and can pass through the placental barrier. Moreover, SFN has antioxidant and anti-apoptotic functions and is considered as a bioactive antioxidant with significant neuroprotective effects. Nano-sulforaphane (Nano-SFN, sulforaphane nanoparticles) was prepared by self-assembly using biocompatible, biodegradable methoxy polyethylene glycol 5000-b-polyglutamic acid 10,000 (mPEG5K-PGA10K) as the substrate, to explore the new application of Nano-SFN and its modified compounds as leading compounds in protecting against the abnormal development of the embryonic nervous system.

RESULTS

The results show that Nano-SFN could protect against PhIP-induced central nervous system (CNS, derived from neural tube) and peripheral nervous system (PNS, derived from neural crest cells, NCCs) defects and neural tube defects (NTDs), and increase the embryo survival rate.

CONCLUSIONS

This study indicates that Nano-SFN can effectively alleviate the developmental defects of embryonic nervous system induced by PhIP in the microenvironment and has a protective effect on embryonic development. It not only helps with expanding the application of SFN and improving its medicinal value, but also provides a possibility of SFN being developed as a novel drug for neuroprotection.

Maternal Overweight and Obesity and Risk of Congenital Heart Defects

BACKGROUND

Congenital heart defects are more frequent in offspring of mothers with overweight or obesity. However, associations between maternal overweight and obesity, and risks of complex and specific heart defects are not clear.

OBJECTIVES

This study sought to analyze associations between maternal overweight and obesity severity and rates of complex and specific heart defects.

METHODS

This was a population-based cohort study in Sweden, including 2,050,491 live singleton infants born between 1992 and 2012. Data on maternal and infant characteristics, and diagnoses of congenital heart defects were retrieved from nationwide registries. Maternal body mass index (BMI) was categorized as underweight (BMI <18.5 kg/m²), normal weight (BMI 18.5 to <25 kg/m²), overweight (BMI 25 to <30 kg/m²), obesity class I (BMI 30 to <35 kg/m²), class II (BMI 35 to <40 kg/m²), and class III (BMI ≥40 kg/m²). Outcomes included complex heart defects (tetralogy of Fallot, transposition of the great arteries, atrial septal defects [ASD], aortic arch defects, and single-ventricle heart) and subgroups of specific heart defects diagnosed up to 5 years of age. The authors calculated adjusted prevalence rate ratios (PRRs) with 95% confidence intervals.

RESULTS

A total of 28,628 (1.40%, N = 2,050,491) children had at least 1 congenital heart defect. PRRs of aortic arch defects increased with maternal obesity severity. Compared with offspring of normal weight mothers, PRRs of aortic arch defects and transposition of the great arteries were doubled in offspring of mothers with severe obesity. PRRs of ASD and persistent ductus arteriosus in term infants increased with maternal BMI.

CONCLUSIONS

PRRs of aortic branch defects, ASD, and persistent ductus arteriosus increase with maternal obesity severity.

Bcl-2 expression in a diabetic embryopathy model in presence of polyamines

The frequency of congenital malformations is 3-5 times higher in mothers with pregestational diabetes mellitus than in general population. Apparently, this problem is due to change in the expression of apoptotic and antiapoptotic genes induced by the oxidative stress derived from the diabetes/hyperglycemia. One of these genes is Bcl-2, which is associated with the control and inhibition of apoptosis. The purpose of the present work was to study the effect of polyamine addition over expression of Bcl-2 gene in a model of diabetic embryopathy. For this, gestational day 10.5 (GD10.5) rat embryos were incubated at 37°C for 24 h in control medium, medium with high glucose, or medium with high glucose and supplemented with spermidine or spermine. Post-cultured embryos were harvested and observed to obtain morphological scores; some of them were subjected to molecular biology studies: DNA isolation plus conventional PCR or RNA isolation plus RT-PCR; other embryos were fixed with paraformaldehyde and used for immunohistochemical detection of Bcl-2 protein. Although Bcl-2 mRNA was similarly expressed in all rat embryo treatments, Bcl-2 protein was found only in control-incubated embryos. In conclusion, it seems that the inhibition of Bcl-2 gene expression induced by glucose was not reversed by polyamines.

Ceramide: a novel inducer for neural tube defects

BACKGROUND

Circulating plasma ceramides, a class of bioactive sphingolipids, are elevated in metabolic disorders, including obesity. Infants of women with these disorders are at 2- to 3-fold greater risk for developing a neural tube defect (NTD). This study aimed to test the effects of embryonic exposure to C2-ceramides (C2) during neural tube closure. Preliminary data shows an increase in NTDs in chick embryos after C2 exposure, and addresses potential mechanisms.

RESULTS

Cell and embryo models were used to examine redox shifts after ceramide exposure. While undifferentiated P19 cells were resistant to ceramide exposure, neuronally differentiated P19 cells exhibited an oxidizing shift. Consistent with these observations, GSH E _h curves revealed a shift to a more oxidized state in C2 treated embryos without increasing apoptosis or changing Pax3 expression, however cell proliferation was lower. Neural tube defects were observed in 45% of chick embryos exposed to C2, compared to 12% in control embryos.

CONCLUSIONS

C2 exposure during critical developmental stages increased the frequency of NTDs in the avian model. Increased ROS generation in cell culture, along with the more oxidative GSH E _h profiles of C2 exposed cells and embryos, support a model wherein ceramide affects neural tube closure via altered tissue redox environments.

Hyperglycemia differentially affects proliferation, apoptosis, and BNIP3 and p53 mRNA expression of human umbilical cord Wharton's jelly cells from non-diabetic and diabetic pregnancies

Diabetes in pregnancy constitutes an unfavorable environment for embryonic and fetal development, where the child has a higher risk of perinatal morbidity and mortality, with high incidence of congenital malformations and predisposition to long-term metabolic diseases that increase with a hypercaloric diet. To analyze whether hyperglycemia differentially affects proliferation, apoptosis, and mRNA expression in cells from children of normoglycemic pregnancies (NGPs) and diabetes mellitus pregnancies (DMPs), we used umbilical cord Wharton jelly cells as a research model. Proliferation assays were performed to analyze growth and determine the doubling time, and the rate of apoptosis was determined by flow cytometry-annexin-V assays. AMPK, BNIP3, HIF1α, and p53 mRNA gene expression was assessed by semi-quantitative RT-PCR. We found that hyperglycemia decreased proliferation in a statistically significant manner in NGP cells treated with 40 mM D-glucose and in DMP cells treated with 30 and 40 mM D-glucose. Apoptosis increased in hyperglycemic conditions in NGP and DMP cells. mRNA expression of BNIP3 and p53 was significantly increased in cells from DMPs but not in cells from NGPs. We found evidence that maternal irregular metabolic conditions, like diabetes with hyperglycemia in culture, affect biological properties of fetal cells. These observations could be a constituent of fetal programming.

CBP/p300 inhibitor C646 prevents high glucose exposure induced neuroepithelial cell proliferation

BACKGROUND

Maternal diabetes related neural tube defects (NTDs) are a result of oxidative stress and apoptosis. However, the molecular mechanism behind the pathogenesis is not fully understood. Here, we report that high glucose exposure-induced epigenetic changes influence histone H4 acetylation and neuroepithelial cell proliferation. We also show that the acetyltransferase inhibitor C646 can prevent high glucose induced changes in histone H4 acetylation and neuroepithelial cell proliferation.

METHODS

By using LC-MS/MS as an unbiased approach, we screened the histone acetylation profile in an E9 neuroepithelial cell line (NE-4C) under high glucose exposure. We further explored the mechanism in cells in vitro and in maternal diabetes-induced mouse embryos in vivo.

RESULTS

We identified 35 core histone acetylation marks in normal E9 neuroepithelial cells, whereas high glucose exposure resulted in novel acetylation sites on H4K31 and H4K44. Acetylation levels of embryonic development associated H4K5/K8/K12/K16 increased in neuroepithelial cells exposed to high glucose in vitro and in brain tissue from maternal diabetes induced exencephalic embryos in vivo. Further, mRNA level of histone acetyltransferase CBP encoded gene Crebbp was significantly increased both in vitro and in vivo. The addition of C646, a selective inhibitor for CBP/p300, significantly rescued increase of H4K5/K8/K12/K16 acetylation levels and H3S10pi-labeled neuroepithelial cell proliferation induced by high glucose exposure.

CONCLUSION

Our data provide complementary insights for potential mechanisms of maternal diabetes induced NTDs.

Neural crest development in Xenopus requires Protocadherin 7 at the lateral neural crest border

In vertebrates, the neural crest is a unique population of pluripotent cells whose development is dependent on signaling from neighboring tissues. Cadherin family members, including protocadherins, are emerging as major players in neural crest development, largely through their roles in cell adhesion and sorting in embryonic tissues. Here, we show that Protocadherin 7 (Pcdh7), previously shown to function in sensorial layer integrity and neural tube closure in Xenopus, is also involved in neural crest specification and survival. Pcdh7 expression partly overlaps the neural crest domain at the lateral neural crest border. Pcdh7 knockdown in embryos does not alter neural crest induction; however, neural crest specification markers, including Snail2 and Sox9, are lost, due to apoptosis of the neural crest starting after stage 13. Pcdh7 knockdown also results in downregulation of Wnt11b; both of which are co-expressed in the sensorial layer lateral to the neural crest, suggestive of a role for Wnt11b in the neural crest apoptosis. Confirming this role, apoptosis, Snail2 expression and the developmental fate of the neural crest can be partially rescued by ectopic expression of Wnt11b. These results indicate that Pcdh7 plays an important role in maintaining the sensorial layer at the lateral neural crest border, which is necessary for the secretion of survival factors, including Wnt11b.

Clinical and risk factor analysis of cloacal defects in the National Birth Defects Prevention Study

Cloacal exstrophy (CE) and persistent cloaca (PC) (alternatively termed urorectal septum malformation sequence [URSMS]), represent two major cloacal defects (CDs). Clinical characteristics and risk factors often are studied for both defects combined, rather than exploring if these defects have different etiologies. We enumerated clinical features for 47 CE and 54 PC (inclusive of URSMS) cases from the National Birth Defects Prevention Study. Thirty-three CE cases were classified as isolated and 14 as multiple (presence of unassociated major defects); respective totals for PC cases were 26 and 28. We compared selected child and maternal characteristics between 11,829 non-malformed controls and CE and PC cases using chi-square or Fisher's exact tests. Compared to controls, CE and PC cases were statistically more likely (p < 0.05) to be preterm; CE cases were more likely to be multiple births. We conducted logistic regression analysis to estimate odds ratios and 95% confidence intervals for any CD, CE, and PC with selected self-reported maternal prepregnancy and periconceptional (one month prior to 3 months following conception) exposures. In crude and adjusted analyses, we observed significant positive associations for any CD, CE, and PC with use of any fertility medication or assisted reproductive technology procedure. Significant positive associations observed only in crude analyses were any CD with maternal obesity or use of progesterone, any CD and CE with any x-ray, and any CD and PC with use of folate antagonist medications. Our findings provide some of the first insights into potential differing etiologies for CE and PC.

Maternal diabetes causes developmental delay and death in early-somite mouse embryos

Maternal diabetes causes congenital malformations and delays embryonic growth in the offspring. We investigated effects of maternal diabetes on mouse embryos during gastrulation and early organogenesis (ED7.5–11.5). Female mice were made diabetic with streptozotocin, treated with controlled-release insulin implants, and mated. Maternal blood glucose concentrations increased up to embryonic day (ED) 8.5. Maternal hyperglycemia induced severe growth retardation (approx.1 day) in 53% of the embryos on ED8.5, death in most of these embryos on ED9.5, and the termination of pregnancy on ED10.5 in litters with >20% dead embryos. Due to this selection, developmental delays and reduction in litter size were no longer observed thereafter in diabetic pregnancies. Male and female embryos were equally sensitive. High-throughput mRNA sequencing and pathway analysis of differentially expressed genes showed that retarded embryos failed to mount the adaptive suppression of gene expression that characterized non-retarded embryos (cell proliferation, cytoskeletal remodeling, oxidative phosphorylation). We conclude that failure of perigastrulation embryos of diabetic mothers to grow and survive is associated with their failure to shut down pathways that are strongly down-regulated in otherwise similar non-retarded embryos. Embryos that survive the early and generalized adverse effect of maternal diabetes, therefore, appear the subset in which malformations become manifest.

Embryonic defence mechanisms against glucose-dependent oxidative stress require enhanced expression of Alx3 to prevent malformations during diabetic pregnancy

Oxidative stress constitutes a major cause for increased risk of congenital malformations associated to severe hyperglycaemia during pregnancy. Mutations in the gene encoding the transcription factor ALX3 cause congenital craniofacial and neural tube defects. Since oxidative stress and lack of ALX3 favour excessive embryonic apoptosis, we investigated whether ALX3-deficiency further increases the risk of embryonic damage during gestational hyperglycaemia in mice. We found that congenital malformations associated to ALX3-deficiency are enhanced in diabetic pregnancies. Increased expression of genes encoding oxidative stress-scavenging enzymes in embryos from diabetic mothers was blunted in the absence of ALX3, leading to increased oxidative stress. Levels of ALX3 increased in response to glucose, but ALX3 did not activate oxidative stress defence genes directly. Instead, ALX3 stimulated the transcription of Foxo1, a master regulator of oxidative stress-scavenging genes, by binding to a newly identified binding site located in the Foxo1 promoter. Our data identify ALX3 as an important component of the defence mechanisms against the occurrence of developmental malformations during diabetic gestations, stimulating the expression of oxidative stress-scavenging genes in a glucose-dependent manner via Foxo1 activation. Thus, ALX3 deficiency provides a novel molecular mechanism for developmental defects arising from maternal hyperglycaemia.

The effect of inhibiting glycinamide ribonucleotide formyl transferase on the development of neural tube in mice

Background

Folate deficiency is closely related to the development of neural tube defects (NTDs). However, the exact mechanism is not completely understood. This study aims to induce murine NTDs by inhibiting one of the folate metabolic pathways, de novo purine synthesis and preliminarily investigate the potential mechanisms. The key enzyme, glycinamide ribonucleotide formyl transferase (GARFT) was inhibited by a specific inhibitor, lometrexol (DDATHF) in the pregnant mice.

Methods

Pregnant mice were intraperitoneally injected with various doses of DDATHF on gestational day 7.5 and embryos were examined for the presence of NTDs on gestational day 11.5. GARFT activity and levels of ATP, GTP, dATP and dGTP were detected in embryonic brain tissue. Proliferation and apoptosis was analyzed by real-time quantitative polymerase chain reaction (RT-qPCR), immunohistochemical assay and western blotting.

Results

40 mg kg⁻¹ body weight (b/w) of DDATHF caused the highest incidence of NTDs (30.8 %) and therefore was selected as the optimal dose to establish murine NTDs. The GARFT activity and levels of ATP, GTP, dATP and dGTP in embryonic brain tissue were significantly decreased after DDATHF treatment. Furthermore, Levels of proliferation-related genes (Pcna, Foxg1 and Ptch1) were downregulated and apoptosis-related genes (Bax, Casp8 and Casp9) were upregulated. Expression of phosphohistone H3 was significantly decreased while expression of cleaved caspase-3 was greatly increased.

Conclusions

Results indicate that DDATHF induced murine NTDs by disturbing purine metabolism and further led to abnormal proliferation and apoptosis.

Electronic supplementary material

The online version of this article (doi:10.1186/s12986-016-0114-x) contains supplementary material, which is available to authorized users.

Amelioration of intracellular stress and reduction of neural tube defects in embryos of diabetic mice by phytochemical quercetin

Diabetes mellitus in early pregnancy causes birth defects, including neural tube defects (NTDs). Hyperglycemia increases production of nitric oxide (NO) through NO synthase 2 (Nos2) and reactive oxygen species (ROS), generating nitrosative and oxidative stress conditions in the embryo. The present study aimed to target nitrosative stress using a naturally occurring Nos2 inhibitor, quercetin, to prevent NTDs in the embryos of diabetic mice. Daily administration of quercetin to diabetic pregnant mice during the hyperglycemia-susceptible period of organogenesis significantly reduced NTDs and cell apoptosis in the embryos, compared with those of vehicle-treated diabetic pregnant mice. Using HPLC-coupled ESI-MS/MS, quercetin metabolites, including methylated and sulfonylated derivatives, were detected in the conceptuses. The methylated metabolite, 3-O-methylquercetin, was shown to reduce ROS level in embryonic stem cells cultured in high glucose. Quercetin treatment decreased the levels of Nos2 expression, protein nitrosylation, and protein nitration, alleviating nitrosative stress. Quercetin increased the expression of superoxide dismutase 1 and 2, and reduced the levels of oxidative stress markers. Expression of genes of redox regulating enzymes and DNA damage repair factors was upregulated. Our study demonstrates that quercetin ameliorates intracellular stresses, regulates gene expression, and reduces embryonic malformations in diabetic pregnancy.

Abnormal O-GlcNAcylation of Pax3 Occurring from Hyperglycemia-Induced Neural Tube Defects Is Ameliorated by Carnosine But Not Folic Acid in Chicken Embryos

Neural tube defects (NTDs) are among the most common of the embryonic abnormalities associated with hyperglycemic gestation. In this study, the molecular mechanisms of embryonic neurogenesis influenced by hyperglycemia was investigated using chicken embryo models. High-concentration glucose was administered into chicken eggs and resulted in increased plasma and brain tissue glucose, and suppressed expression of glucose transporters (GLUTs). The rate of NTD positively correlated with hyperglycemia. Furthermore, abnormally increased O-GlcNAcylation, a nutritionally responsive modification, of the key neural tube marker Pax3 protein led to the loss of this protein. This loss was not observed in a folate-deficiency NTD induced by methotrexate. Carnosine, an endogenous dipeptide, showed significant recovery effects on neural tube development. In contrast, folic acid, a well-known periconceptional agent, surprisingly showed relatively minimal effect. Higher expression levels of the Pax3 protein were found in the carnosine-treated groups, while lower expression levels were found in folic acid groups. Furthermore, the abnormal O-GlcNAcylation of the Pax3 protein was restored by carnosine. These results suggest new insights into using endogenous nutrients for the protection of embryonic neurodevelopment affected by diabetes gestation. The abnormal excessive O-GlcNAcylation of Pax3 may be responsible for the neural tube defects associated with hyperglycemia.

High glucose environment inhibits cranial neural crest survival by activating excessive autophagy in the chick embryo

High glucose levels induced by maternal diabetes could lead to defects in neural crest development during embryogenesis, but the cellular mechanism is still not understood. In this study, we observed a defect in chick cranial skeleton, especially parietal bone development in the presence of high glucose levels, which is derived from cranial neural crest cells (CNCC). In early chick embryo, we found that inducing high glucose levels could inhibit the development of CNCC, however, cell proliferation was not significantly involved. Nevertheless, apoptotic CNCC increased in the presence of high levels of glucose. In addition, the expression of apoptosis and autophagy relevant genes were elevated by high glucose treatment. Next, the application of beads soaked in either an autophagy stimulator (Tunicamycin) or inhibitor (Hydroxychloroquine) functionally proved that autophagy was involved in regulating the production of CNCC in the presence of high glucose levels. Our observations suggest that the ERK pathway, rather than the mTOR pathway, most likely participates in mediating the autophagy induced by high glucose. Taken together, our observations indicated that exposure to high levels of glucose could inhibit the survival of CNCC by affecting cell apoptosis, which might result from the dysregulation of the autophagic process.

Assessing developmental toxicity of caffeine and sweeteners in medaka (Oryzias latipes)

The use of artificial sweeteners (ASWs) has increased and become more widespread, and consequently ASWs have appeared in aquatic environments around the world. However, their safety to the health of humans and wildlife remains inconclusive. In this study, using medaka embryos (Oryzias latipes), we investigated developmental toxicity of aspartame (ASP) and saccharin (SAC). Since ASWs are often consumed with caffeine (CAF) and CAF with sucrose (SUC), we tested biological activities of these four substances and the mixtures of CAF with each sweetener. The embryos were exposed to ASP at 0.2 and 1.0 mM, SAC at 0.005 and 0.050 mM, CAF at 0.05 and 0.5 mM, or SUC at 29 and 146 mM, starting from less than 5 h post fertilization until hatch. Control embryos were treated with embryo solution only. Several endpoints were used to evaluate embryonic development. Some of the hatchlings were also tested for anxiety-like behavior with the white preference test. The results showed that all four substances and the mixtures of CAF with the sweeteners affected development. The most sensitive endpoints were the heart rate, eye density, and hatchling body length. The hatchlings of several treatment groups also exhibited anxiety-like behavior. We then used the Integrated Biological Response (IBR) as an index to evaluate the overall developmental toxicity of the substances. We found that the ranking of developmental toxicity was SAC > CAF > ASP > SUC, and there was a cumulative effect when CAF was combined with the sweeteners.

Influence of intracellular zinc on cultures of rat cardiac neural crest cells

BACKGROUND

Developmental zinc (Zn) deficiency increases the incidence of heart anomalies in rat fetuses, in regions and structures derived from the outflow tract. Given that the development of the outflow tract requires the presence of cardiac neural crest cells (cNCC), we speculated that Zn deficiency selectively kills cNCC and could lead to heart malformations.

METHODS

Cardiac NCC were isolated from E10.5 rat embryos and cultured in control media (CTRL), media containing 3 μM of the cell permeable metal chelator N, N, N', N'-tetrakis (2-pyridylmethyl) ethylene diamine (TPEN), or in TPEN-treated media supplemented with 3 μM Zn (TPEN + Zn). Cardiac NCC were collected after 6, 8, and 24 h of treatment to assess cell viability, proliferation, and apoptosis.

RESULTS

The addition of TPEN to the culture media reduced free intracellular Zn pools and cell viability as assessed by low ATP production, compared to cells grown in control or Zn-supplemented media. There was an accumulation of reactive oxygen species, a release of mitochondrial cytochrome c into the cytoplasm, and an increased cellular expression of active caspase-3 in TPEN-treated cNCC compared to cNCC cultured in CTRL or TPEN + Zn media.

CONCLUSION

Zn deficiency can result in oxidative stress in cNCC, and subsequent decreases in their population and metabolic activity. These data support the concept that Zn deficiency associated developmental heart defects may arise in part as a consequence of altered cNCC metabolism.

Importance of maternal diabetes on the chronological deregulation of the intrauterine development: an experimental study in rat

We investigated whether maternal diabetes induced in rats using streptozotocin (STZ) on Day 5 of pregnancy affects the intrauterine developmental timeline. A total of 30 pregnant Sprague-Dawley diabetic rats (DRs) and 20 control rats (CRs) were used to obtain 21-day fetuses (F21) and newborn (NB) pups. Gestational age, weight, and body size were recorded as were the maxillofacial morphometry and morphohistological characteristics of the limbs. In DRs, pregnancy continued for ∼1.7 days, and delivery occurred 23 days postcoitus (DPC). In this group, the number of pups was lower, and 13% had maxillofacial defects. F21 in the DR group had lower weights and were smaller; moreover, the morphological characteristics of the maxillofacial structures, derived from the neural crest, were discordant with their chronological gestational age, resembling 18- to 19-day-old fetuses. These deficiencies were counterbalanced in NB pups. We conclude that hyperglycemia, which results from maternal diabetes and precedes embryo implantation, deregulates the intrauterine developmental timeline, restricts embryo-fetal growth, and primarily delays the remodeling and maturation of the structures derived from neural crest cells.

Adenosine monophosphate-activated protein kinase activation enhances embryonic neural stem cell apoptosis in a mouse model of amyotrophic lateral sclerosis

Alterations in embryonic neural stem cells play crucial roles in the pathogenesis of amyotrophic lateral sclerosis. We hypothesized that embryonic neural stem cells from SOD1(G93A) individuals might be more susceptible to oxidative injury, resulting in a propensity for neurodegeneration at later stages. In this study, embryonic neural stem cells obtained from human superoxide dismutase 1 mutant (SOD1(G93A)) and wild-type (SOD1(WT)) mouse models were exposed to H2O2. We assayed cell viability with mitochondrial succinic dehydrogenase colorimetric reagent, and measured cell apoptosis by flow cytometry. Moreover, we evaluated the expression of the adenosine monophosphate-activated protein kinase (AMPK) α-subunit, paired box 3 (Pax3) protein, and p53 in western blot analyses. Compared with SOD1(WT) cells, SOD1(G93A) embryonic neural stem cells were more likely to undergo H2O2-induced apoptosis. Phosphorylation of AMPKα in SOD1(G93A) cells was higher than that in SOD1(WT) cells. Pax3 expression was inversely correlated with the phosphorylation levels of AMPKα. p53 protein levels were also correlated with AMPKα phosphorylation levels. Compound C, an inhibitor of AMPKα, attenuated the effects of H2O2. These results suggest that embryonic neural stem cells from SOD1(G93A) mice are more susceptible to apoptosis in the presence of oxidative stress compared with those from wild-type controls, and the effects are mainly mediated by Pax3 and p53 in the AMPKα pathway.

Mangiferin facilitates islet regeneration and β-cell proliferation through upregulation of cell cycle and β-cell regeneration regulators

Mangiferin, a xanthonoid found in plants including mangoes and iris unguicularis, was suggested in previous studies to have anti-hyperglycemic function, though the underlying mechanisms are largely unknown. This study was designed to determine the therapeutic effect of mangiferin by the regeneration of β-cells in mice following 70% partial pancreatectomy (PPx), and to explore the mechanisms of mangiferin-induced β-cell proliferation. For this purpose, adult C57BL/6J mice after 7–14 days post-PPx, or a sham operation were subjected to mangiferin (30 and 90 mg/kg body weight) or control solvent injection. Mangiferin-treated mice exhibited an improved glycemia and glucose tolerance, increased serum insulin levels, enhanced β-cell hyperplasia, elevated β-cell proliferation and reduced β-cell apoptosis. Further dissection at the molecular level showed several key regulators of cell cycle, such as cyclin D1, D2 and cyclin-dependent kinase 4 (Cdk4) were significantly up-regulated in mangiferin-treated mice. In addition, critical genes related to β-cell regeneration, such as pancreatic and duodenal homeobox 1 (PDX-1), neurogenin 3 (Ngn3), glucose transporter 2 (GLUT-2), Forkhead box protein O1 (Foxo-1), and glucokinase (GCK), were found to be promoted by mangiferin at both the mRNA and protein expression level. Thus, mangiferin administration markedly facilitates β-cell proliferation and islet regeneration, likely by regulating essential genes in the cell cycle and the process of islet regeneration. These effects therefore suggest that mangiferin bears a therapeutic potential in preventing and/or treating the diabetes.

Vinyl chloride monomer (VCM) induces high occurrence of neural tube defects in embryonic mouse brain during neurulation

The aim of this study was to explore the direct embryonic teratogenicity of vinyl chloride monomer (VCM), especially the toxic effects on the early development of the nervous system and its underlying mechanisms. Pregnant mice at embryonic day 6.5 (E6.5) were injected with different doses of VCM (200, 400 and 600 mg/kg) and embryos were harvested at E10.5. Our results showed that doses higher than 400 mg/kg of VCM increased the incidence of malformed embryos, especially the neural tube defects (NTDs). In addition, high-dose of VCM decreased mitotic figure counts in the neuroepithelium and enhanced the percentage of cells in G0/G1 phase, while they were reduced in S phase. The more VCM was injected into mice, the fewer positive PCNA cells were seen and the more positive TUNEL cells were observed in the neuroepithelium. Moreover, significant increases in the levels of caspase-3 protein were observed in NTD embryos. Our results demonstrate that during early pregnancy, exposure to doses higher than 400 mg/kg of VCM increases the incidence of malformations and particularly the rate of NTDs. High-dose of VCM inhibits the proliferation of neural cells and induces cell apoptosis, leading to an imbalance in the ratio of proliferation and apoptosis. Meanwhile, the apoptosis of neuroepithelial cells might be accelerated by the activation of the caspase-3 pathway, and it might be a reason for NTDs.

Caspase 3 activation and PARP cleavage in lymphocytes from newborn babies of diabetic mothers with unbalanced glycaemic control

Several epidemiological studies showed that gestational diabetes mellitus is the most frequent metabolic disorder of pregnancy, the pathogenesis of which has yet to be completely clarified. The aim of this study was to investigate the presence and processing of caspase 3 (Casp3) and poly(ADP-ribose) polymerase 1 (PARP1) in cord blood lymphocytes as markers of apoptosis in relation to glycaemic control during intrauterine life. Our results showed a specific positive correlation between the levels of active Casp3 (17-19 kDa) and the inactive form of PARP1 (89 kDa) in lymphocytes isolated from newborn babies of diabetic women with unbalanced glycaemic control, with a direct correlation between the activation of casp3 and the inactivation of PARP1, that makes lymphocytes unresponsive towards lipopolysaccharide stimulation, highlighting an altered functional response. Besides more studies are required to fully correlate the activation of the apoptotic process during the intrauterine life with the foetal health later in life, our study indicates that a cord blood lymphocyte, an easily accessible source, is informative about the activation of apoptotic stimuli in circulating cells of newborn babies in relation to the glycaemic control reached by the mother during pregnancy.

New concepts in diabetic embryopathy

Diabetes mellitus is responsible for nearly 10% of fetal anomalies in diabetic pregnancies. Although aggressive perinatal care and glycemic control are available in developed countries, the birth defect rate in diabetic pregnancies remains higher than that in the general population. Major cellular activities (ie, proliferation and apoptosis) and intracellular metabolic conditions (ie, nitrosative, oxidative, and endoplasmic reticulum stress) have been shown to be associated with diabetic embryopathy using animal models. Translating advances made in animal studies into clinical applications in humans requires collaborative efforts across the basic research, preclinical, and clinical communities.

Mouse as a model for multifactorial inheritance of neural tube defects

Neural tube defects (NTDs) such as spina bifida and anencephaly are some of the most common structural birth defects found in humans. These defects occur due to failures of neurulation, a process where the flat neural plate rolls into a tube. In spite of their prevalence, the causes of NTDs are poorly understood. The multifactorial threshold model best describes the pattern of inheritance of NTDs where multiple undefined gene variants interact with environmental factors to cause an NTD. To date, mouse models have implicated a multitude of genes as required for neurulation, providing a mechanistic understanding of the cellular and molecular pathways that control neurulation. However, the majority of these mouse models exhibit NTDs with a Mendelian pattern of inheritance. Still, many examples of multifactorial inheritance have been demonstrated in mouse models of NTDs. These include null and hypomorphic alleles of neurulation genes that interact in a complex fashion with other genetic mutations or environmental factors to cause NTDs. These models have implicated several genes and pathways for testing as candidates for the genetic basis of NTDs in humans, resulting in identification of putative pathogenic mutations in some patients. Mouse models also provide an experimental paradigm to gain a mechanistic understanding of the environmental factors that influence NTD occurrence, such as folic acid and maternal diabetes, and have led to the discovery of additional preventative nutritional supplements such as inositol. This review provides examples of how multifactorial inheritance of NTDs can be modeled in the mouse.

Network-based identification of novel connections among apoptotic signaling pathways in cancer

MicroRNAs (miRNAs), highly conserved, non-coding endogenous RNA and nearly ~22 nucleotides (nt) in length, are well-known to regulate several apoptotic pathways in cancer. In this study, we computationally constructed the initial human apoptotic PPI network by several online databases, and further integrated these high-throughput datasets into a Naïve Bayesian model to predict protein functional connections. Based on the modified apoptotic network, we identified several apoptotic hub proteins such as TP53, SRC, M3K3/5/8, cyclin-dependent kinase2/6, TNFR16/19, and TGF-β receptor 1/2. Subsequently, we identified some microRNAs that could target the aforementioned apoptotic hub proteins by using TargetScan, PicTar, and Diana-MicroH. In conclusion, these results demonstrate the PPI network-based identification of new connections amongst apoptotic pathways in cancer, which may shed new light on the intricate relationships between core apoptotic pathways and some targeted miRNAs in human cancers.

Reduction in embryonic malformations and alleviation of endoplasmic reticulum stress by nitric oxide synthase inhibition in diabetic embryopathy

Maternal diabetes-induced neural tube defects (NTDs) are associated with increased programmed cell death (apoptosis) in the neuroepithelium, which is related to intracellular nitrosative stress. To alleviate nitrosative stress, diabetic pregnant mice were fed via gavage an inhibitor of nitric oxide (NO) synthase (NOS) 2, L-N6-(1-iminoethyl)-lysine (L-NIL; 80 mg/kg), once a day from embryonic (E) day 7.5 to 9.5 during early stages of neurulation. The treatment significantly reduced NTD rate in the embryos, compared with that in vehicle (normal saline)-treated diabetic group. In addition to alleviation of nitrosative stress, endoplasmic reticulum (ER) stress was also ameliorated, assessed by quantification of associated factors. Apoptosis was reduced, indicated by caspase 8 activation. These results show that nitrosative stress is important in diabetes-induced NTDs via exacerbating ER stress, leading to increased apoptosis. Oral treatment with NOS-2 inhibitor alleviates nitrosative and ER stress, decreases apoptosis, and reduces NTDs in the embryos, providing information for further interventional studies to reduce diabetes-associated birth defects.

The essential role of protein kinase Cδ in diabetes-induced neural tube defects

BACKGROUND

Maternal diabetes causes neural tube defects (NTDs) in the embryos via activating protein kinase Cs (PKCs), which regulate programmed cell death (apoptosis). The aims of this study are to investigate the role of proapoptotic PKCδ in NTD formation and the underlying mechanisms.

METHODS

PKCδ heterozygous (pkcδ(+/-)) female mice were diabetic (DM) induced by intravenous injection of streptozotocin. Occurrence of NTDs was evaluated at embryonic day 11.5 and compared between wild type (WT) and PKCδ homozygous (pkcδ(-/-)) embryos. Changes in oxidative and endoplasmic reticulum (ER) stress-associated factors and stress-response c-Jun N-terminal kinases (JNKs) were assessed using Western blot assay.

RESULTS

Compared to DM/WT, the DM/PKCδ(-/-) embryos had significantly lower NTD rate and lower levels of oxidative and ER stress factors and JNK activation. These values were similar to those in the non-diabetic control group.

CONCLUSION

PKCδ plays a critical role in diabetes-induced NTDs, potentially through increasing oxidative and ER stress and JNK-associated stress-response pathways.

Fetal hyperglycemia alters lung structural development in neonatal rat

Maternal diabetes is associated with increased risk for abnormal fetal organogenesis, but its effects on the developing lungs are still insufficiently known. To determine the effect of maternal hyperglycemia on postnatal lung development, we studied lung structural and cellular changes in newborn rats exposed to intrauterine hyperglycemia. We induced hyperglycemia in Sprague-Dawley rats with i.p. streptozotocin before pregnancy and allowed the hyperglycemic and control dams deliver at term. Lungs were obtained on postnatal day (d) 0, d7, and d14 and analyzed for lung weight and morphology, as well as cellular apoptosis (TUNEL staining) and proliferation (PCNA staining). Quantitative micro-CT analysis of the lung vasculature was additionally performed at d14. At birth, maternal hyperglycemia resulted in decreased relative lung weight, thinner alveolar septa and increased cellular apoptosis and proliferation, when compared to controls. At 1 and 2 weeks of age pulmonary cell apoptosis and alveolar chord length remained unchanged, but cell proliferation and number of secondary crests were increased in the hyperglycemia-exposed neonatal lungs in comparison with the controls. Density of small arterioles on histological examination and the structure of pulmonary arterial vasculature in micro-CT analysis of the neonatal lungs were not influenced by maternal hyperglycemia. Our results suggest, that maternal hyperglycemia is related to developmental structural alterations in postnatal rat lungs. These early changes may reflect aberrant maturational adaptation in response to the hyperglycemic fetal environment.

The role of oxidative stress in the pathophysiology of gestational diabetes mellitus

Normal human pregnancy is considered a state of enhanced oxidative stress. In pregnancy, it plays important roles in embryo development, implantation, placental development and function, fetal development, and labor. However, pathologic pregnancies, including gestational diabetes mellitus (GDM), are associated with a heightened level of oxidative stress, owing to both overproduction of free radicals and/or a defect in the antioxidant defenses. This has important implications on the mother, placental function, and fetal well-being. Animal models of diabetes have confirmed the important role of oxidative stress in the etiology of congenital malformations; the relative immaturity of the antioxidant system facilitates the exposure of embryos and fetuses to the damaging effects of oxidative stress. Of note, there are only a few clinical studies evaluating the potential beneficial effects of antioxidants in GDM. Thus, whether or not increased antioxidant intake can reduce the complications of GDM in both mother and fetus needs to be explored. This review provides an overview and updated data on our current understanding of the complications associated with oxidative changes in GDM.

A Unique Case of Eosinophilic Pancreatitis and Anencephaly in the Fetus of a Type I Diabetic Mother

Pancreatic infiltration with eosinophils is an uncommon finding with numerous etiologies. While two rare cases of eosinophilic pancreatitis in infants born to Type I diabetic mothers have been reported once in the English literature and once in the French literature, we present the additional finding of anencephaly in a 34 week old fetus. Although the pancreas was grossly unremarkable, histological inspection demonstrated an eosinophilic infiltrate in the fibrous septae and islets of Langerhans along with hypertrophy and hyperplasia of the pancreatic islets.

Protein kinase Cβ2 inhibition reduces hyperglycemia-induced neural tube defects through suppression of a caspase 8-triggered apoptotic pathway

OBJECTIVE

Neural tube defects in diabetic embryopathy are associated with increased protein kinase C (PKC)β2 activity and programmed cell death (apoptosis). The apoptosis is triggered by caspase 8, which activates members of the Bcl-2 and caspase families, such as Bid and caspase 3. Whether PKCβ2 regulates caspase 8-induced apoptosis remains to be addressed.

STUDY DESIGN

Mouse embryos at embryonic day 8.5 were cultured in a high concentration of glucose (22 mmol/L) and treated with PKCβ2 inhibitor (50 nmol/L) for 48 hours. The levels of apoptosis and activation of apoptotic factors were quantified using the terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick end labeling and Western blot assays, respectively.

RESULTS

Reduction in the rate of neural tube defect by PKCβ2 inhibition is associated with significant decreases in the levels of apoptosis, and caspase 8, caspase 3, and Bid activation, and cytochrome C release from mitochondria, to the similar levels as in euglycemic controls (8.3 mmol/L; P < .05).

CONCLUSION

PKCβ2 influences a caspase 8-regulated apoptotic pathway in diabetic embryopathy.

Resveratrol prevents embryonic oxidative stress and apoptosis associated with diabetic embryopathy and improves glucose and lipid profile of diabetic dam

SCOPE

Diabetic embryopathy, a consequence of diabetic pregnancy, is associated with increase in embryonic oxidative stress and apoptosis, which lead to severe embryonic damage at early stage of organogenesis.

METHODS AND RESULTS

This study investigated if resveratrol, found in red grapes and blue-berries, may prevent diabetes-induced oxidative stress and apoptosis in embryos and have beneficial effects in diabetic dams. A rodent model of diabetic embryopathy was used. Diabetes was associated with lowered reduced glutathione levels (26.98%), increased total thiol (100.47%) and lipid peroxidation (124.73%) in embryos, and increased blood sugar (384.03%), cholesterol (98.39%) and triglyceride (1025.35%) in diabetic dams. Increased apoptosis (272.20%) was also observed in the embryos of diabetic dams. Administration of resveratrol (100 mg/kg body weight (b.w.)) during pregnancy prevented both oxidative stress and apoptosis in embryos. Resveratrol reduced embryonic maldevelopment by improving embryo weight (41.23%), crown rump length (16.50%) and somite number (11.22%). It further improved the glucose (33.32%) and lipid (cholesterol 41.74%, triglyceride 60.64%) profile of the diabetic dams, which also represents the protective role of resveratrol in diabetes.

CONCLUSION

Resveratrol was found to prevent embryonic oxidative stress and apoptosis. It also improved glucose and lipid profile of diabetic dams, indicating the beneficial effects in diabetic pregnancy.

Maternal intake of folic acid and neural crest stem cells

Maternal folic acid (FA) intake has beneficial effects in preventing neural tube defects and may also play a role in the prevention of adult onset diseases such as Alzheimer's disease, dementia, neuropsychiatric disorders, cardiovascular diseases, and cerebral ischemia. This review will focus on the effects of maternal FA intake on neural crest stem cell proliferation and differentiation. Although FA is generally considered beneficial, it has the potential of promoting cell proliferation at the expense of differentiation. In some situations, this may lead to miscarriage or postnatal developmental abnormalities. Therefore, a blind approach such as "FA for everyone" is not necessarily the best course of action. Ultimately, the best approach for FA supplementation, and potentially other nutritional supplements, will include customized patient genomic profiles for determining dose and duration.

Neural tube defect genes and maternal diabetes during pregnancy

BACKGROUND

Maternal diabetes during pregnancy is a well-known teratogen that increases the risk for birth defects, such as neural tube defects (NTDs). We have previously shown that maternal diabetes profoundly affects gene expression in the developing embryo, in particular a suite of known NTD genes. In rodent experimental systems, NTDs present as phenotypes of incomplete penetrance in diabetic pregnancies. This property is difficult to reconcile with observations of consistently altered gene expression in exposed embryos. We here show that maternal diabetes increases the overall variability of gene expression levels in embryos.

RESULTS

Altered gene expression and increased variability of gene expression together may constitute the molecular correlates for incomplete phenotype penetrance.

DISCUSSION

Based on this model, we suggest that maternal diabetes reduces the precision of gene regulation in exposed individuals. Loss of precision in embryonic gene regulation may include changes to the epigenome via deregulated expression of chromatin-modifying factors. Unraveling the mechanisms underlying such epigenetic modifications in diabetic pregnancies will help to understand how teratogenic insults compromise embryonic development and possibly provide avenues for therapeutic intervention.

Animal models in diabetes and pregnancy

The worldwide increase in the incidence of diabetes, the increase in type 2 diabetes in women at reproductive ages, and the cross-generation of the intrauterine programming of type 2 diabetes are the bases for the growing interest in the use of experimental diabetic models in order to gain insight into the mechanisms of induction of developmental alterations in maternal diabetes. In this scenario, experimental models that present the most common features of diabetes in pregnancy are highly required. Several important aspects of human diabetic pregnancies such as the increased rates of spontaneous abortions, malformations, fetoplacental impairments, and offspring diseases in later life can be approached by using the appropriate animal models. The purpose of this review is to give a practical and critical guide into the most frequently used experimental models in diabetes and pregnancy, discuss their advantages and limitations, and describe the aspects of diabetes and pregnancy for which these models are thought to be adequate. This review provides a comprehensive view and an extensive analysis of the different models and phenotypes addressed in diabetic animals throughout pregnancy. The review includes an analysis of the surgical, chemical-induced, and genetic experimental models of diabetes and an evaluation of their use to analyze early pregnancy defects, induction of congenital malformations, placental and fetal alterations, and the intrauterine programming of metabolic diseases in the offspring's later life.

Genetics and development of neural tube defects

Congenital defects of neural tube closure (neural tube defects; NTDs) are among the commonest and most severe disorders of the fetus and newborn. Disturbance of any of the sequential events of embryonic neurulation produce NTDs, with the phenotype (eg anencephaly, spina bifida) varying depending on the region of neural tube that remains open. While mutation of > 200 genes is known to cause NTDs in mice, the pattern of occurrence in humans suggests a multifactorial polygenic or oligogenic aetiology. This emphasizes the importance of gene-gene and gene-environment interactions in the origins of these defects. A number of cell biological functions are essential for neural tube closure, with defects of the cytoskeleton, cell cycle and molecular regulation of cell viability prominent among the mouse NTD mutants. Many transcriptional regulators and proteins that affect chromatin structure are also required for neural tube closure, although the downstream molecular pathways regulated by these proteins is unknown. Some key signalling pathways for NTDs have been identified: over-activation of sonic hedgehog signalling and loss of function in the planar cell polarity (non-canonical Wnt) pathway are potent causes of NTD, with requirements also for retinoid and inositol signalling. Folic acid supplementation is an effective method for primary prevention of a proportion of NTDs in both humans and mice, although the embryonic mechanism of folate action remains unclear. Folic acid-resistant cases can be prevented by inositol supplementation in mice, raising the possibility that this could lead to an additional preventive strategy for human NTDs in future.