Neural crest development in fetal alcohol syndrome

Recent Developments in Single-Cell Metabolomics by Mass Spectrometry─A Perspective

Recent advancements in single-cell (sc) resolution analyses, particularly in sc transcriptomics and sc proteomics, have revolutionized our ability to probe and understand cellular heterogeneity. The study of metabolism through small molecules, metabolomics, provides an additional level of information otherwise unattainable by transcriptomics or proteomics by shedding light on the metabolic pathways that translate gene expression into functional outcomes. Metabolic heterogeneity, critical in health and disease, impacts developmental outcomes, disease progression, and treatment responses. However, dedicated approaches probing the sc metabolome have not reached the maturity of other sc omics technologies. Over the past decade, innovations in sc metabolomics have addressed some of the practical limitations, including cell isolation, signal sensitivity, and throughput. To fully exploit their potential in biological research, however, remaining challenges must be thoroughly addressed. Additionally, integrating sc metabolomics with orthogonal sc techniques will be required to validate relevant results and gain systems-level understanding. This perspective offers a broad-stroke overview of recent mass spectrometry (MS)-based sc metabolomics advancements, focusing on ongoing challenges from a biologist's viewpoint, aimed at addressing pertinent and innovative biological questions. Additionally, we emphasize the use of orthogonal approaches and showcase biological systems that these sophisticated methodologies are apt to explore.

Low to Moderate Prenatal Alcohol Exposure and Facial Shape of Children at Age 6 to 8 Years

Importance

In addition to confirmed prenatal alcohol exposure and severe neurodevelopmental deficits, three cardinal facial features are included in the diagnostic criteria for fetal alcohol spectrum disorder. It is not understood whether subtle facial characteristics occur in children without a diagnosis but who were exposed to a range of common pregnancy drinking patterns and, if so, whether these persist throughout childhood.

Objective

To determine whether subtle changes in facial shape with prenatal alcohol exposure found in 12-month-old children were evident at age 6 to 8 years using extended phenotyping methods and, if so, whether facial characteristics were similar to those seen in fetal alcohol spectrum disorder.

Design, Setting, and Participants

In a prospective cohort study in Melbourne, Victoria, Australia, commencing in July 2011 with follow-up through April 2021, pregnant women were recruited in the first trimester from low-risk, metropolitan, public maternity clinics over a period of 12 months. Three-dimensional craniofacial images from 549 children of European descent taken at age 12 months (n = 421 images) and 6 to 8 years (n = 363) were included. Data analysis was performed from May 2021 to October 2024.

Exposures

Predominantly low to moderate prenatal alcohol exposure in the first trimester or throughout pregnancy compared with controls without prenatal alcohol exposure.

Main Outcomes and Measures

Following hierarchical facial segmentation, phenotype descriptors were computed. Hypothesis testing was performed for 63 facial modules to analyze different facial parts independently using principal component analysis and response-based imputed predictor (RIP) scores. Comparison was made with a clinical discovery sample of facial images of children with a confirmed diagnosis of partial or full fetal alcohol syndrome.

Results

A total of 549 children took part in the 3-dimensional craniofacial image analysis, of whom 235 (42.8%) contributed an image at both time points. Time 1 included 421 children, comprising 336 children (159 [47.3%] female) with any prenatal alcohol exposure and 85 control children (45 [52.9%] female); time 2 included 363 children, comprising 260 children with any prenatal alcohol exposure (125 [48.1%] female; mean [SD] age, 6.9 [0.7] years) and 103 control children (53 [51.5%] female; mean [SD] age, 6.8 [0.7] years). At both time points, there was consistent evidence for an association between prenatal alcohol exposure and the shape of the eyes (eg, module 15: RIP partial Spearman ρ, 0.19 [95% CI, 0.10-0.29; P < .001] at 6-8 years) and nose (eg, module 5: RIP partial Spearman ρ, 0.19 [95% CI, 0.09-0.27; P < .001] at 6-8 years), whether exposure occurred only in trimester 1 or throughout pregnancy. Facial variations observed differed from those in the clinical discovery sample.

Conclusions and Relevance

Low to moderate prenatal alcohol exposure was associated with characteristic changes in the face, which persisted until at least 6 to 8 years of age. A linear association between alcohol exposure levels and facial shape was not supported.

Ethanol Induces Craniofacial Defects in Bmp Mutants Independent of nkx2.3 by Elevating Cranial Neural Crest Cell Apoptosis

Background: Craniofacial malformations lie at the heart of fetal alcohol spectrum disorders (FASDs). While there is growing evidence for a genetic component in FASDs, little is known of the cellular mechanisms underlying these ethanol-sensitive loci in facial development. The bone morphogenetic protein (Bmp) signaling pathway-dependent endoderm pouch formation is a key mechanism in facial development. We have previously shown that multiple Bmp mutants are sensitized to ethanol-induced facial defects. However, ethanol does not directly impact Bmp signaling. This suggests that downstream effectors, like nkx2.3, may mediate the impact of ethanol on Bmp mutants. Methods: We use an ethanol exposure paradigm with nkx2.3 knockdown approaches to test if nkx2.3 loss sensitizes Bmp mutants to ethanol-induced facial defects. We combine morphometric approaches with immunofluorescence and a hybridization chain reaction to examine the cellular mechanisms underlying Bmp-ethanol interactions. Results: We show that Bmp-ethanol interactions alter the morphology of the endodermal pouches, independent of nkx2.3 gene expression. Knockdown of nkx2.3 does not sensitize wild-type or Bmp mutants to ethanol-induced facial defects. However, we did observe a significant increase in CNCC apoptosis in ethanol-treated Bmp mutants, suggesting an ethanol sensitive, Bmp-dependent signaling pathway driving tissue interactions at the heart of FASDs. Conclusions: Collectively, our work builds on the mechanistic understanding of ethanol-sensitive genes and lays the groundwork for complex multi-tissue signaling events that have yet to be explored. Ultimately, our work provides a mechanistic paradigm of ethanol-induced facial defects and connects ethanol exposure with complex tissue signaling events that drive development.

Ethanol induces craniofacial defects in Bmp mutants independent of nkx2.3 by elevating cranial neural crest cell apoptosis

Background

Fetal Alcohol Spectrum Disorders (FASD) describes a wide range of neurological defects and craniofacial malformations associated with prenatal ethanol exposure. While there is growing evidence for a genetic component to FASD, little is known of the cellular mechanisms underlying these ethanol-sensitive loci in facial development. Endoderm morphogenesis to form lateral protrusions called pouches is one key mechanism in facial development. We have previously shown that multiple members of the Bone Morphogenetic Pathway (Bmp) signaling pathway, a key regulator of pouch formation, interacts with ethanol disrupting facial development. However, ethanol does not directly impact Bmp signaling suggesting that downstream effectors, like nkx2.3 may mediate the impact of ethanol on Bmp mutants.

Methods

Here we use an ethanol exposure paradigm with nkx2.3 knockdown approaches to test if loss of nkx2.3 sensitizes Bmp mutants to ethanol induced facial defects. We then combine a morphometric approach with Hybridization Chain Reaction and immunofluorescence to examine the cellular mechanisms underlying Bmp-ethanol interactions.

Results

We show that Bmp-ethanol interactions alter morphology of the endodermal pouches, independent of nkx2.3 gene expression. Morpholino knock down of nkx2.3 does not sensitize wild type or bmp4 mutant larvae to ethanol-induced facial defects. However, we did observe a significant increase CNCC apoptosis in ethanol-treated Bmp mutants.

Conclusions

Collectively, our results suggest that ethanol's mode of action is independent of downstream Bmp effectors, converging on CNCC cell survival. Ultimately, our work provides a mechanistic paradigm of ethanol-induced facial defects and connects ethanol exposure with concrete cellular events.

Bone morphogenetic protein signaling pathway- Ethanol interactions disrupt palate formation independent of gata3

Fetal Alcohol Spectrum Disorders (FASD) describes a wide array of neurological defects and craniofacial malformations, associated with ethanol teratogenicity. While there is growing evidence for a genetic component to FASD, little is known of the genes underlying these ethanol-induced defects. Along with timing and dosage, genetic predispositions may help explain the variability within FASD. From a screen for gene-ethanol interactions, we found that mutants for Bmp signaling components are ethanol-sensitive leading to defects in the zebrafish palate. Loss of Bmp signaling results in reductions in gata3 expression in the maxillary domain of the neural crest in the 1st pharyngeal arch, leading to palate defects while upregulation of human GATA3 rescues these defects. Here, we show that ethanol-treated Bmp mutants exhibit misshaped and/or broken trabeculae. Surprisingly, up regulation of GATA3 does not rescue ethanol-induced palate defects and gata3 expression was not altered in ethanol-treated Bmp mutants or dorsomorphin-treated larvae. Timing of ethanol sensitivity shows that Bmp mutants are ethanol sensitive from 10 to 18 hours post-fertilization (hpf), prior to Bmp's regulation of gata3 in palate formation. This is consistent with our previous work with dorsomorphin-dependent knock down of Bmp signaling from 10 to 18 hpf disrupting endoderm formation and subsequent jaw development. Overall, this suggests that ethanol disrupts Bmp-dependent palate development independent of and earlier than the role of gata3 in palate formation by disrupting epithelial development. Ultimately, these data demonstrate that zebrafish is a useful model to identify and characterize gene-ethanol interactions and this work will directly inform our understanding of FASD.

Alcohol induces p53-mediated apoptosis in neural crest by stimulating an AMPK-mediated suppression of TORC1, S6K, and ribosomal biogenesis

Prenatal alcohol exposure is a leading cause of permanent neurodevelopmental disability and can feature distinctive craniofacial deficits that partly originate from the apoptotic deletion of craniofacial progenitors, a stem cell lineage called the neural crest (NC). We recently demonstrated that alcohol causes nucleolar stress in NC through its suppression of ribosome biogenesis (RBG) and this suppression is causative in their p53/MDM2-mediated apoptosis. Here, we show that this nucleolar stress originates from alcohol's activation of AMPK, which suppresses TORC1 and the p70/S6K-mediated stimulation of RBG. Alcohol-exposed cells of the pluripotent, primary cranial NC line O9-1 were evaluated with respect to their S6K, TORC1, and AMPK activity. The functional impact of these signals with respect to RBG, p53, and apoptosis were assessed using gain-of-function constructs and small molecule mediators. Alcohol rapidly (<2 hr) increased pAMPK, pTSC2, and pRaptor, and reduced both total and pS6K in NC cells. These changes persisted for at least 12 hr to 18 hr following alcohol exposure. Attenuation of these signals via gain- or loss-of-function approaches that targeted AMPK, S6K, or TORC1 prevented alcohol's suppression of rRNA synthesis and the induction of p53-stimulated apoptosis. We conclude that alcohol induces ribosome dysbiogenesis and activates their p53/MDM2-mediated apoptosis via its activation of pAMPK, which in turn activates TSC2 and Raptor to suppress the TORC1/S6K-mediated promotion of ribosome biogenesis. This represents a novel mechanism underlying alcohol's neurotoxicity and is consistent with findings that TORC1/S6K networks are critical for cranial NC survival.

Bone Morphogenetic Protein signaling pathway - ethanol interactions disrupt palate formation independent of gata3

Fetal Alcohol Spectrum Disorders (FASD) describes a wide array of neurological defects and craniofacial malformations, associated with ethanol teratogenicity. While there is growing evidence for a genetic component to FASD, little is known of the genes underlying these ethanol-induced defects. Along with timing and dosage, genetic predispositions may help explain the variability within FASD. From a screen for gene-ethanol interactions, we found that mutants for Bmp signaling components are ethanol-sensitive leading to defects in the zebrafish palate. Loss of Bmp signaling results in reductions in gata3 expression in the maxillary domain of the neural crest in the 1st pharyngeal arch, leading to palate defects while upregulation of human GATA3 rescues these defects. Here, we show that ethanol-treated Bmp mutants exhibit misshaped and/or broken trabeculae. Surprisingly, up regulation of GATA3 does not rescue ethanol-induced palate defects and gata3 expression was not altered in ethanol-treated Bmp mutants or dorsomorphin-treated larvae. Timing of ethanol sensitivity shows that Bmp mutants are ethanol sensitive from 10-18 hours post-fertilization (hpf), prior to Bmp's regulation of gata3 in palate formation. This is consistent with our previous work with dorsomorphin-dependent knock down of Bmp signaling from 10-18 hpf disrupting endoderm formation and subsequent jaw development. Overall, this suggests that ethanol disrupts Bmp-dependent palate development independent of and earlier than the role of gata3 in palate formation by disrupting epithelial development. Ultimately, these data demonstrate that zebrafish is a useful model to identify and characterize gene-ethanol interactions and this work will directly inform our understanding of FASD.

Highlights

Bmp pathway mutants are ethanol sensitive resulting in palate defects. Ethanol disrupts Bmp-dependent palate development independent of gata3 . Timing of ethanol sensitivity suggests ethanol disrupts Bmp-dependent epithelial morphogenesis.

Purmorphamine Alters Anxiety-Like Behavior and Expression of Hedgehog Cascade Components in Rat Brain after Alcohol Withdrawal

Disturbances in the Hedgehog (Hh) signaling play an important role in dysmorphogenesis of bone tissue and central nervous system during prenatal alcohol exposure, which underlies development of fetal alcohol syndrome. The involvement of Hh proteins in the mechanisms of alcohol intake in adults remains obscure. We investigated the role of the Hh cascade in voluntary ethanol drinking and development of anxiety-like behavior (ALB) during early abstinence and assessed changes in the expression of Hh pathway components in different brain regions of male Wistar rats in a model of voluntary alcohol drinking using the intermittent access to 20% ethanol in a two-bottle choice procedure. Purmorphamine (Hh cascade activator and Smoothened receptor agonist) was administered intraperitoneally at a dose of 5 mg/kg body weight prior to 16-20 sessions of alcohol access. Purmorphamine had no effect on the ethanol preference; however, rats exposed to ethanol and receiving purmorphamine demonstrated changes in the ALB during the early abstinence period. Alcohol drinking affected the content of the Sonic hedgehog (Shh) and Patched mRNAs only in the amygdala. In rats exposed to ethanol and receiving purmorphamine, the level of Shh mRNA in the amygdala correlated negatively with the time spent in the open arms of the elevated plus maze. Therefore, we demonstrated for the first time that alterations in the Hh cascade induced by administration of purmorphamine did not affect alcohol preference in voluntary alcohol drinking. It was suggested that Hh cascade is involved in the development of anxiety after alcohol withdrawal through specific changes in the Hh cascade components in the amygdala.

Alcohol induces p53-mediated apoptosis in neural crest by stimulating an AMPK-mediated suppression of TORC1, S6K, and ribosomal biogenesis

Prenatal alcohol exposure is a leading cause of permanent neurodevelopmental disability and can feature distinctive craniofacial deficits that partly originate from the apoptotic deletion of craniofacial progenitors, a stem cell lineage called the neural crest (NC). We recently demonstrated that alcohol causes nucleolar stress in NC through its suppression of ribosome biogenesis (RBG) and this suppression is causative in their p53/MDM2-mediated apoptosis. Here, we show that this nucleolar stress originates from alcohol's activation of AMPK, which suppresses TORC1 and the p70/S6K-mediated stimulation of RBG. Alcohol-exposed cells of the pluripotent, primary cranial NC line O9-1 were evaluated with respect to their S6K, TORC1, and AMPK activity. The functional impact of these signals with respect to RBG, p53, and apoptosis were assessed using gain-of-function constructs and small molecule mediators. Alcohol rapidly (<2hr) increased pAMPK, pTSC2, and pRaptor, and reduced both total and pS6K in NC cells. These changes persisted for at least 12hr to 18hr following alcohol exposure. Attenuation of these signals via gain- or loss-of-function approaches that targeted AMPK, S6K, or TORC1 prevented alcohol's suppression of rRNA synthesis and the induction of p53-stimulated apoptosis. We conclude that alcohol induces ribosome dysbiogenesis and activates their p53/MDM2-mediated apoptosis via its activation of pAMPK, which in turn activates TSC2 and Raptor to suppress the TORC1/S6K-mediated promotion of ribosome biogenesis. This represents a novel mechanism underlying alcohol's neurotoxicity and is consistent with findings that TORC1/S6K networks are critical for cranial NC survival.

An overview of current advances in perinatal alcohol exposure and pathogenesis of fetal alcohol spectrum disorders

The adverse use of alcohol is a serious global public health problem. Maternal alcohol consumption during pregnancy usually causes prenatal alcohol exposure (PAE) in the developing fetus, leading to a spectrum of disorders known as fetal alcohol spectrum disorders (FASD) and even fetal alcohol syndrome (FAS) throughout the lifelong sufferers. The prevalence of FASD is approximately 7.7 per 1,000 worldwide, and is even higher in developed regions. Generally, Ethanol in alcoholic beverages can impair embryonic neurological development through multiple pathways leading to FASD. Among them, the leading mechanism of FASDs is attributed to ethanol-induced neuroinflammatory damage to the central nervous system (CNS). Although the underlying molecular mechanisms remain unclear, the remaining multiple pathological mechanisms is likely due to the neurotoxic damage of ethanol and the resultant neuronal loss. Regardless of the molecular pathway, the ultimate outcome of the developing CNS exposed to ethanol is almost always the destruction and apoptosis of neurons, which leads to the reduction of neurons and further the development of FASD. In this review, we systematically summarize the current research progress on the pathogenesis of FASD, which hopefully provides new insights into differential early diagnosis, treatment and prevention for patents with FASD.

Clinical and Genetic Correlation in Neurocristopathies: Bridging a Precision Medicine Gap

Neurocristopathies (NCPs) encompass a spectrum of disorders arising from issues during the formation and migration of neural crest cells (NCCs). NCCs undergo epithelial-mesenchymal transition (EMT) and upon key developmental gene deregulation, fetuses and neonates are prone to exhibit diverse manifestations depending on the affected area. These conditions are generally rare and often have a genetic basis, with many following Mendelian inheritance patterns, thus making them perfect candidates for precision medicine. Examples include cranial NCPs, like Goldenhar syndrome and Axenfeld-Rieger syndrome; cardiac-vagal NCPs, such as DiGeorge syndrome; truncal NCPs, like congenital central hypoventilation syndrome and Waardenburg syndrome; and enteric NCPs, such as Hirschsprung disease. Additionally, NCCs' migratory and differentiating nature makes their derivatives prone to tumors, with various cancer types categorized based on their NCC origin. Representative examples include schwannomas and pheochromocytomas. This review summarizes current knowledge of diseases arising from defects in NCCs' specification and highlights the potential of precision medicine to remedy a clinical phenotype by targeting the genotype, particularly important given that those affected are primarily infants and young children.

Primary and secondary defects of the thymus

The thymus is the primary site of T-cell development, enabling generation, and selection of a diverse repertoire of T cells that recognize non-self, whilst remaining tolerant to self- antigens. Severe congenital disorders of thymic development (athymia) can be fatal if left untreated due to infections, and thymic tissue implantation is the only cure. While newborn screening for severe combined immune deficiency has allowed improved detection at birth of congenital athymia, thymic disorders acquired later in life are still underrecognized and assessing the quality of thymic function in such conditions remains a challenge. The thymus is sensitive to injury elicited from a variety of endogenous and exogenous factors, and its self-renewal capacity decreases with age. Secondary and age-related forms of thymic dysfunction may lead to an increased risk of infections, malignancy, and autoimmunity. Promising results have been obtained in preclinical models and clinical trials upon administration of soluble factors promoting thymic regeneration, but to date no therapy is approved for clinical use. In this review we provide a background on thymus development, function, and age-related involution. We discuss disease mechanisms, diagnostic, and therapeutic approaches for primary and secondary thymic defects.

Adult William's Syndrome: The Cause of an Unusual Vasculopathy and Biliary Abnormalities

A man in his 50s was diagnosed with William's syndrome (WS) following the investigation of severe vasculopathy and bile duct abnormalities. The vascular lesions included: right carotid artery hypoplasia, tortuous dilated left carotid artery, severe aortic hypoplasia, and pulmonary branch arterial stenoses. The bile ducts were dilated with damaged and inflamed intrahepatic ducts. The patient had been labeled with fetal alcohol syndrome as a consequence of his mother's alcohol addiction. The etiology is thought to be the combined effects and his genetic condition and prenatal alcohol exposure.

Effects of In Utero EtOH Exposure on 18S Ribosomal RNA Processing: Contribution to Fetal Alcohol Spectrum Disorder

Fetal alcohol spectrum disorders (FASD) are leading causes of neurodevelopmental disability. The mechanisms by which alcohol (EtOH) disrupts fetal brain development are incompletely understood, as are the genetic factors that modify individual vulnerability. Because the phenotype abnormalities of FASD are so varied and widespread, we investigated whether fetal exposure to EtOH disrupts ribosome biogenesis and the processing of pre-ribosomal RNAs and ribosome assembly, by determining the effect of exposure to EtOH on the developmental expression of 18S rRNA and its cleaved forms, members of a novel class of short non-coding RNAs (srRNAs). In vitro neuronal cultures and fetal brains (11-22 weeks) were collected according to an IRB-approved protocol. Twenty EtOH-exposed brains from the first and second trimester were compared with ten unexposed controls matched for gestational age and fetal gender. Twenty fetal-brain-derived exosomes (FB-Es) were isolated from matching maternal blood. RNA was isolated using Qiagen RNA isolation kits. Fetal brain srRNA expression was quantified by ddPCR. srRNAs were expressed in the human brain and FB-Es during fetal development. EtOH exposure slightly decreased srRNA expression (1.1-fold; p = 0.03). Addition of srRNAs to in vitro neuronal cultures inhibited EtOH-induced caspase-3 activation (1.6-fold, p = 0.002) and increased cell survival (4.7%, p = 0.034). The addition of exogenous srRNAs reversed the EtOH-mediated downregulation of srRNAs (2-fold, p = 0.002). EtOH exposure suppressed expression of srRNAs in the developing brain, increased activity of caspase-3, and inhibited neuronal survival. Exogenous srRNAs reversed this effect, possibly by stabilizing endogenous srRNAs, or by increasing the association of cellular proteins with srRNAs, modifying gene transcription. Finally, the reduction in 18S rRNA levels correlated closely with the reduction in fetal eye diameter, an anatomical hallmark of FASD. The findings suggest a potential mechanism for EtOH-mediated neurotoxicity via alterations in 18S rRNA processing and the use of FB-Es for early diagnosis of FASD. Ribosome biogenesis may be a novel target to ameliorate FASD in utero or after birth. These findings are consistent with observations that gene-environment interactions contribute to FASD vulnerability.

Neural crest cells and fetal alcohol spectrum disorders: Mechanisms and potential targets for prevention

Fetal alcohol spectrum disorders (FASD) are a group of preventable and nongenetic birth defects caused by prenatal alcohol exposure that can result in a range of cognitive, behavioral, emotional, and functioning deficits, as well as craniofacial dysmorphology and other congenital defects. During embryonic development, neural crest cells (NCCs) play a critical role in giving rise to many cell types in the developing embryos, including those in the peripheral nervous system and craniofacial structures. Ethanol exposure during this critical period can have detrimental effects on NCC induction, migration, differentiation, and survival, leading to a broad range of structural and functional abnormalities observed in individuals with FASD. This review article provides an overview of the current knowledge on the detrimental effects of ethanol on NCC induction, migration, differentiation, and survival. The article also examines the molecular mechanisms involved in ethanol-induced NCC dysfunction, such as oxidative stress, altered gene expression, apoptosis, epigenetic modifications, and other signaling pathways. Furthermore, the review highlights potential therapeutic strategies for preventing or mitigating the detrimental effects of ethanol on NCCs and reducing the risk of FASD. Overall, this article offers a comprehensive overview of the current understanding of the impact of ethanol on NCCs and its role in FASD, shedding light on potential avenues for future research and intervention.

Characterising the Effect of Wnt/β-Catenin Signalling on Melanocyte Development and Patterning: Insights from Zebrafish (Danio rerio)

Zebrafish (Danio rerio) is a well-established model organism for studying melanocyte biology due to its remarkable similarity to humans. The Wnt signalling pathway is a conserved signal transduction pathway that plays a crucial role in embryonic development and regulates many aspects of the melanocyte lineage. Our study was designed to investigate the effect of Wnt signalling activity on zebrafish melanocyte development and patterning. Stereo-microscopic examinations were used to screen for changes in melanocyte count, specific phenotypic differences, and distribution in zebrafish, while microscopic software tools were used to analyse the differences in pigment dispersion of melanocytes exposed to LiCl (Wnt enhancer) and W-C59 (Wnt inhibitor). Samples exposed to W-C59 showed low melanocyte densities and defects in melanocyte phenotype and patterning, whereas LiCl exposure demonstrated a stimulatory effect on most aspects of melanocyte development. Our study demonstrates the crucial role of Wnt signalling in melanocyte lineage and emphasises the importance of a balanced Wnt signalling level for proper melanocyte development and patterning.

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.

Embryonic ethanol exposure disrupts craniofacial neuromuscular integration in zebrafish larvae

Forming a vertebrate head involves the meticulous integration of multiple tissue types during development. Prenatal alcohol exposure is known to cause a variety of birth defects, especially to tissues in the vertebrate head. However, a systematic analysis of coordinated defects across tissues in the head is lacking. Here, we delineate the effects of ethanol on individual tissue types and their integration during craniofacial development. We found that exposure to 1% ethanol induced ectopic cranial muscle and nerve defects with only slight effects on skeletal pattern. Ectopic muscles were, however, unaccompanied by ectopic tendons and could be partially rescued by anesthetizing the larvae before muscle fibers appeared. This finding suggests that the ectopic muscles result from fiber detachment and are not due to an underlying muscle patterning defect. Interestingly, immobilization did not rescue the nerve defects, thus ethanol has an independent effect on each tissue even though they are linked in developmental time and space. Time-course experiments demonstrated an increase in nerve defects with ethanol exposure between 48hpf-4dpf. Time-lapse imaging confirmed the absence of nerve pathfinding or misrouting defects until 48hpf. These results indicate that ethanol-induced nerve defects occur at the time of muscle innervation and after musculoskeletal patterning. Further, we investigated the effect of ethanol on the neuromuscular junctions of the craniofacial muscles and found a reduced number of postsynaptic receptors with no significant effect on the presynaptic terminals. Our study shows that craniofacial soft tissues are particularly susceptible to ethanol-induced damage and that these defects appear independent from one another. Thus, the effects of ethanol on the vertebrate head appear highly pleiotropic.

Ethanol exposure perturbs sea urchin development and disrupts developmental timing

Ethanol is a known vertebrate teratogen that causes craniofacial defects as a component of fetal alcohol syndrome (FAS). Our results show that sea urchin embryos treated with ethanol similarly show broad skeletal patterning defects, potentially analogous to the defects associated with FAS. The sea urchin larval skeleton is a simple patterning system that involves only two cell types: the primary mesenchymal cells (PMCs) that secrete the calcium carbonate skeleton and the ectodermal cells that provide migratory, positional, and differentiation cues for the PMCs. Perturbations in RA biosynthesis and Hh signaling pathways are thought to be causal for the FAS phenotype in vertebrates. Surprisingly, our results indicate that these pathways are not functionally relevant for the teratogenic effects of ethanol in developing sea urchins. We found that developmental morphology as well as the expression of some ectodermal and PMC genes was delayed by ethanol exposure. Temporal transcriptome analysis revealed significant impacts of ethanol on signaling and metabolic gene expression, and a disruption in the timing of GRN gene expression that includes both delayed and precocious gene expression throughout the specification network. We conclude that the skeletal patterning perturbations in ethanol-treated embryos likely arise from a loss of temporal synchrony within and between the instructive and responsive tissues.

Moderate alcohol consumption during pregnancy increases potency of two different drugs (the antifungal fluconazole and the antiepileptic valproate) in inducing craniofacial defects: prediction by the in vitro rat whole embryo culture

The prenatal exposure to ethanol (Eth), fluconazole (FLUCO) and sodium valproate (VPA) is related to effects on development, producing characteristic syndromic pictures. Among embryotoxic effects described for the three molecules, the alteration on craniofacial morphogenesis is a common feature in humans and animal models, including rodent embryos developed in vitro. The aim of the present work is to evaluate the developmental effects of low Eth serum concentration (17 mM, corresponding to the legal limit to drive in UK, USA, Canada, and many other countries) in mixture with increasing realistic concentrations of the antifungal drug FLUCO (62.5-500 µM) or with increasing realistic concentrations of the antiepileptic drug VPA (31.25-250 µM). Groups exposed to Eth alone (17-127.5 mM), FLUCO alone (62.5-500 µM) or VPA alone (31.25-750 µM) were also included. The chosen alternative animal model was the post-implantation rat whole embryo culture (WEC). E9.5 embryos were exposed in vitro to the test molecules during the whole test period (48 h, corresponding to the developmental stages characteristics of any vertebrate, for human embryos post-fertilization days 23-31). Data were statistically analyzed and processed for modelling applying the benchmark dose (BMD) and relative potency factor (RPF) approaches. Concentration-related effects on facial outcomes were observed in all experimental groups, with a significant enhancement in the groups co-exposed with Eth in comparison to the single exposures. Data obtained by the present work suggest an additional alert for the assumption of even low levels of alcohol in pregnant women during FLUCO or VPA therapy.

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.

Zebrafish Model of Stickler Syndrome Suggests a Role for Col2a1a in the Neural Crest during Early Eye Development

Most cases of Stickler syndrome are due to autosomal-dominant COL2A1 gene mutations leading to abnormal type II collagen. Ocular findings include axial eye lengthening with vitreal degeneration and early-onset glaucoma, which can result in vision loss. Although COL2A1 is a major player in cartilage and bone formation, its specific role in eye development remains elusive. We investigated the role of Col2a1a in neural crest migration and differentiation during early zebrafish eye development. In situ hybridization, immunofluorescence, live imaging, exogenous treatments [10 μM diethylaminobenzaldehyde (DEAB), 100 nM all-trans retinoic acid (RA) and 1-3% ethanol (ETOH)] and morpholino oligonucleotide (MO) injections were used to analyze wildtype Casper (roy-/-;nacre-/-), TgBAC(col2a1a::EGFP), Tg(sox10::EGFP) and Tg(foxd3::EGFP) embryos. Col2a1a colocalized with Foxd3- and Sox10-positive cells in the anterior segment and neural crest-derived jaw. Col2a1a expression was regulated by RA and inhibited by 3% ETOH. Furthermore, MO knockdown of Col2a1a delayed jaw formation and disrupted the ocular anterior segment neural crest migration of Sox10-positive cells. Interestingly, human COL2A1 protein rescued the MO effects. Altogether, these results suggest that Col2a1a is a downstream target of RA in the cranial neural crest and is required for both craniofacial and eye development.

Effect of Embryonic Alcohol Exposure on Craniofacial and Skin Melanocyte Development: Insights from Zebrafish (Danio rerio)

Alcohol is a common addictive substance and prenatal alcohol exposure could cause fetal alcohol spectrum disorder (FASD) and can lead to various birth defects. The small teleost zebrafish (Danio rerio) has been identified as a fine animal model in developmental biology and toxicological research. Zebrafish models are widely used to study the harmful effects of alcohol and limited studies are available on the craniofacial and skin malformations associated with FASD. The present study attempts to investigate the effect of alcohol on early zebrafish embryonic development. The effects of prenatal alcohol exposure on neural crest cell-derived organ formation, including pharyngeal dentition, palatal bones and skin melanocytes were analysed. Whole-mount cartilage and bone staining and imaging techniques were applied to determine the effects of alcohol on the above-mentioned structures. The tooth size and shape were affected by alcohol exposure, but the number of teeth in the pharyngeal dentition was not affected. Only first-generation teeth showed size differences. The alcohol-exposed ethmoid bone, which is homologous to the human hard palate, was smaller and less dense in cell arrangement compared with the control medial ethmoid bone. The skin pigmentation defects included reduced melanocyte density, melanin contraction, smaller melanocyte surface area and aberrations in melanosome dispersion, revealing that alcohol significantly influenced and downregulated each and every step of the melanocyte developmental process. This descriptive study summarises the effects of alcohol on the development of neural crest cell-derived structures and highlights the importance of zebrafish in studying the phenotypic characteristics of fetal alcohol spectrum disorder.

Bioinformatics Analysis of Hub Genes Involved in Alcohol-Related Hemifacial Microsomia Pathogenesis

OBJECTIVE

Alcohol is a recognized teratogen, and alcohol exposure increases the risk for hemifacial microsomia (HFM) of the fetus during maternal pregnancy. The present study aimed to explore potential mechanisms and verify hub genes of HFM associated with alcohol by bioinformatics methods.

METHODS

First, HFM and alcohol pathogenic genes were obtained. Thereafter, a protein-protein interactional (PPI) network was constructed. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses and molecular complex detection were performed by Metascape. Finally, we used the cytoHubba plugin to screen the hub genes.

RESULTS

A total of 43 HFM genes and 50 optimal alcohol candidate genes were selected. The PPI networks for pathogenic genes contained 93 nodes and 503 edges. Functional enrichment analysis largely focused on tissue formation and development. Two modules were identified from the PPI network, and 10 hub genes were screened out. The genes most relevant to alcohol-induced HFM pathogenesis included CTNNB1, TP53, MYC, HDAC1, and SOX2.

CONCLUSIONS

This study identified some significant hub genes, pathways, and modules of HFM related to alcohol by bioinformatics analyses. Our results suggest that the CTNNB1, TP53, MYC, HDAC1, and SOX B1 gene subfamilies may have played a major role in alcohol-induced HFM.

Identification of Seminal Physical Features of Prenatal Alcohol Exposure by Child Psychologists

Introduction

Prenatal alcohol exposure (PAE) impacts an estimated 5% or more children born in the USA and is associated with life-long neuropsychological deficits. Early identification is essential but access to diagnostic evaluation is limited. This study reports on the effectiveness of training child psychologists to identify and measure the salient physical features of PAE.

Methods

Children, 8–13 years, were divided into two groups: (1) children meeting criteria for PAE (n = 46) and (2) typically developing controls without PAE (TD; n = 36). Child psychologists were trained to reliability measure height, weight, occipital frontal circumference (OFC), and the characteristic facial features of FASD independent of knowledge of PAE history.

Results

Groups differed significantly on meeting the diagnostic criteria proposed by Hoyme et al. (Pediatrics, 138:e20154256, 2016) on height, OFC, upper vermillion border, philtrum, and palpebral fissure length. They did not differ on weight. All children in the alcohol exposed group could be classified as meeting criteria for an FASD whereas none in the unexposed group met criteria.

Discussion

This study demonstrated that child psychologists, blind to PAE history, could be reliably trained to assess the physical features of children with PAE. Because early diagnosis and intervention is of paramount importance, we propose that inclusive diagnostic criteria for FASD and the use of psychologists and other allied health professionals, trained to screen for the diagnosis, should be expanded in clinical practice.

Zebrafish models of alx-linked frontonasal dysplasia reveal a role for Alx1 and Alx3 in the anterior segment and vasculature of the developing eye

The cellular and genetic mechanisms that coordinate formation of facial sensory structures with surrounding skeletal and soft tissue elements remain poorly understood. Alx1, a homeobox transcription factor, is a key regulator of midfacial morphogenesis. ALX1 mutations in humans are linked to severe congenital anomalies of the facial skeleton (frontonasal dysplasia, FND) with malformation or absence of eyes and orbital contents (micro- and anophthalmia). Zebrafish with loss-of-function alx1 mutations develop with craniofacial and ocular defects of variable penetrance, likely due to compensatory upregulation in expression of a paralogous gene, alx3. Here we show that zebrafish alx1;alx3 mutants develop with highly penetrant cranial and ocular defects that resemble human ALX1-linked FND. alx1 and alx3 are expressed in anterior cranial neural crest (aCNC), which gives rise to the anterior neurocranium (ANC), anterior segment structures of the eye and vascular pericytes. Consistent with a functional requirement for alx genes in aCNC, alx1; alx3 mutants develop with nearly absent ANC and grossly aberrant hyaloid vasculature and ocular anterior segment, but normal retina. In vivo lineage labeling identified a requirement for alx1 and alx3 during aCNC migration, and transcriptomic analysis suggested oxidative stress response as a key target mechanism of this function. Oxidative stress is a hallmark of fetal alcohol toxicity, and we found increased penetrance of facial and ocular malformations in alx1 mutants exposed to ethanol, consistent with a protective role for alx1 against ethanol toxicity. Collectively, these data demonstrate a conserved role for zebrafish alx genes in controlling ocular and facial development, and a novel role in protecting these key midfacial structures from ethanol toxicity during embryogenesis. These data also reveal novel roles for alx genes in ocular anterior segment formation and vascular development and suggest that retinal deficits in alx mutants may be secondary to aberrant ocular vascularization and anterior segment defects. This study establishes robust zebrafish models for interrogating conserved genetic mechanisms that coordinate facial and ocular development, and for exploring gene--environment interactions relevant to fetal alcohol syndrome.

Up-regulation of microRNA-34a mediates ethanol-induced impairment of neural crest cell migration in vitro and in zebrafish embryos through modulating epithelial-mesenchymal transition by targeting Snail1

Prenatal ethanol exposure can impair neural crest cell (NCC) development, including NCC survival, differentiation and migration, contributing to the craniofacial dysmorphology in Fetal Alcohol Spectrum Disorders (FASD). Epithelial-mesenchymal transition (EMT) plays an important role in regulating the migration of NCCs. The objective of this study is to determine whether ethanol exposure can suppress NCC migration through inhibiting EMT and whether microRNA-34a (miR-34a) is involved in the ethanol-induced impairment of EMT in NCCs. We found that exposure to 100 mM ethanol significantly inhibited the migration of NCCs. qRT-PCR and Western Blot analysis revealed that exposure to ethanol robustly reduced the mRNA and protein expression of Snail1, a critical transcriptional factor that has a pivotal role in the regulation of EMT. Ethanol exposure also significantly increased the mRNA expression of the Snail1 target gene E-cadherin1 and inhibited EMT in NCCs. We also found that exposure to ethanol significantly elevated the expression of miR-34a that targets Snail1 in NCCs. In addition, down-regulation of miR-34a prevented ethanol-induced repression of Snail1 and diminished ethanol-induced upregulation of Snail1 target gene E-cadherin1 in NCCs. Inhibition of miR-34a restored EMT and prevented ethanol-induced inhibition of NCC migration in vitro and in zebrafish embryos in vivo. These results demonstrate that ethanol-induced upregulation of miR-34a contributes to the impairment of NCC migration through suppressing EMT by targeting Snail1.

Analysis of Gene-Environment Interactions Related to Developmental Disorders

Various genetic and environmental factors are associated with developmental disorders (DDs). It has been suggested that interaction between genetic and environmental factors (G × E) is involved in the etiology of DDs. There are two major approaches to analyze the interaction: genome-wide and candidate gene-based approaches. In this mini-review, we demonstrate how these approaches can be applied to reveal the G × E related to DDs focusing on zebrafish and mouse models. We also discuss novel approaches to analyze the G × E associated with DDs.

Genome-wide Interaction Study Implicates VGLL2 and Alcohol Exposure and PRL and Smoking in Orofacial Cleft Risk

Non-syndromic cleft lip with or without cleft palate (NSCL/P) is a common birth defect, affecting approximately 1 in 700 births. NSCL/P has complex etiology including several known genes and environmental factors; however, known genetic risk variants only account for a small fraction of the heritability of NSCL/P. It is commonly suggested that gene-by-environment (G×E) interactions may help explain some of the “missing” heritability of NSCL/P. We conducted a genome-wide G×E interaction study in cases and controls of European ancestry with three common maternal exposures during pregnancy: alcohol, smoking, and vitamin use using a two-stage design. After selecting 127 loci with suggestive 2df tests for gene and G x E effects, 40 loci showed significant G x E effects after correcting for multiple tests. Notable interactions included SNPs of 6q22 near VGLL2 with alcohol and 6p22.3 near PRL with smoking. These interactions could provide new insights into the etiology of CL/P and new opportunities to modify risk through behavioral changes.

Concomitant genetic defects potentiate the adverse impact of prenatal alcohol exposure on cardiac outflow tract maturation

BACKGROUND

Prenatal alcohol exposure (PAE) is associated with an increased incidence of congenital heart defects (CHD), in particular outflow tract (OFT) defects. However, the variability in the incidence of CHD following PAE has not been fully explored. We hypothesize that a concomitant, relevant genetic defect would potentiate the adverse effect of PAE and partially explain the variability of PAE-induced CHD incidence.

METHODS

The OFT is formed by the second heart field (SHF). Our PAE model consisted of two intraperitoneal injections (3 g/kg, separated by 6 hr) of 30% ethanol on E6.5 during SHF specification. The impact of genetic defects was studied by SHF-specific loss of Delta-like ligand 4 (Dll4), fibroblast growth factor 8 (Fgf8) and Islet1.

RESULTS

Acute PAE alone significantly increased CHD incidence (4% vs. 26%, p = .015) with a particular increase in OFT alignment defects, viz., double outlet right ventricle (0 vs. 9%, p = .02). In embryos with a SHF genetic defect, acute PAE significantly increased CHD incidence (14 vs. 63%, p < .001), including double outlet right ventricle (6 vs. 50%, p < .001) compared to controls. PAE (p = .01) and heterozygous loss of Dll4 (p = .04) were found to independently contribute to CHD incidence, while neither Islet1 nor Fgf8 defects were found to be significant.

CONCLUSIONS

Our model recapitulates the increased incidence of OFT alignment defects seen in the clinic due to PAE. The presence of a concomitant SHF genetic mutation increases the incidence of PAE-related OFT defects. An apparent synergistic interaction between PAE and the loss of DLL4-mediated Notch signaling in OFT alignment requires further analysis.

Zebrafish models of fetal alcohol spectrum disorders

Fetal alcohol spectrum disorder (FASD) describes a wide range of structural deficits and cognitive impairments. FASD impacts up to 5% of children born in the United States each year, making ethanol one of the most common teratogens. Due to limitations and ethical concerns, studies in humans are limited in their ability to study FASD. Animal models have proven critical in identifying and characterizing the mechanisms underlying FASD. In this review, we will focus on the attributes of zebrafish that make it a strong model in which to study ethanol-induced developmental defects. Zebrafish have several attributes that make it an ideal model in which to study FASD. Zebrafish produced large numbers of externally fertilized, translucent embryos. With a high degree of genetic amenability, zebrafish are at the forefront of identifying and characterizing the gene-ethanol interactions that underlie FASD. Work from multiple labs has shown that embryonic ethanol exposures result in defects in craniofacial, cardiac, ocular, and neural development. In addition to structural defects, ethanol-induced cognitive and behavioral impairments have been studied in zebrafish. Building upon these studies, work has identified ethanol-sensitive loci that underlie the developmental defects. However, analyses show there is still much to be learned of these gene-ethanol interactions. The zebrafish is ideally suited to expand our understanding of gene-ethanol interactions and their impact on FASD. Because of the conservation of gene function between zebrafish and humans, these studies will directly translate to studies of candidate genes in human populations and allow for better diagnosis and treatment of FASD.

Prenatal alcohol exposure disrupts Sonic hedgehog pathway and primary cilia genes in the mouse neural tube

Neurulation-stage alcohol exposure (NAE; embryonic day [E] 8-10) is associated with midline craniofacial and CNS defects that likely arise from disruption of morphogen pathways, such as Sonic hedgehog (Shh). Notably, midline anomalies are also a hallmark of genetic ciliopathies such as Joubert syndrome. We tested whether NAE alters Shh pathway signaling and the number and function of primary cilia, organelles critical for Shh pathway transduction. Female C57BL/6 J mice were administered two doses of alcohol (2.9 g/kg/dose) or vehicle on E9. Embryos were collected 6, 12, or 24 h later, and changes to Shh, cell cycle genes, and primary cilia were measured in the rostroventral neural tube (RVNT). Within the first 24 h post-NAE, reductions in Shh pathway and cell cycle gene expression and the ratio of Gli3 forms in the full-length activator state were observed. RVNT volume and cell layer width were reduced at 12 h. In addition, altered expression of multiple cilia-related genes was observed at 6 h post-NAE. As a further test of cilia gene-ethanol interaction, mice heterozygous for Kif3a exhibited perturbed behavior during adolescence following NAE compared to vehicle-treated mice, and Kif3a heterozygosity exacerbated the hyperactive effects of NAE on exploratory activity. These data demonstrate that NAE downregulates the Shh pathway in a region of the neural tube that gives rise to alcohol-sensitive brain structures and identifies disruption of primary cilia function, or a "transient ciliopathy", as a possible cellular mechanism of prenatal alcohol pathogenesis.

Extracellular Vesicles in Premature Aging and Diseases in Adulthood Due to Developmental Exposures

The developmental origins of health and disease (DOHaD) is a paradigm that links prenatal and early life exposures that occur during crucial periods of development to health outcome and risk of disease later in life. Maternal exposures to stress, some psychoactive drugs and alcohol, and environmental chemicals, among others, may result in functional changes in developing fetal tissues, creating a predisposition for disease in the individual as they age. Extracellular vesicles (EVs) may be mediators of both the immediate effects of exposure during development and early childhood as well as the long-term consequences of exposure that lead to increased risk and disease severity later in life. Given the prevalence of diseases with developmental origins, such as cardiovascular disease, neurodegenerative disorders, osteoporosis, metabolic dysfunction, and cancer, it is important to identify persistent mediators of disease risk. In this review, we take this approach, viewing diseases typically associated with aging in light of early life exposures and discuss the potential role of EVs as mediators of lasting consequences.

Toxic and Teratogenic Effects of Prenatal Alcohol Exposure on Fetal Development, Adolescence, and Adulthood

Prenatal alcohol exposure (PAE) can have immediate and long-lasting toxic and teratogenic effects on an individual’s development and health. As a toxicant, alcohol can lead to a variety of physical and neurological anomalies in the fetus that can lead to behavioral and other impairments which may last a lifetime. Recent studies have focused on identifying mechanisms that mediate the immediate teratogenic effects of alcohol on fetal development and mechanisms that facilitate the persistent toxic effects of alcohol on health and predisposition to disease later in life. This review focuses on the contribution of epigenetic modifications and intercellular transporters like extracellular vesicles to the toxicity of PAE and to immediate and long-term consequences on an individual’s health and risk of disease.

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.

Expression of the hippocampal PTCH during early abstinence is associated with drinking patterns in a rat model of voluntary alcohol intake

Perinatal alcohol exposure induces fetal alcohol syndrome partially through Sonic Hedgehog (SHH) impairment; however, the relationship between SHH signaling cascade and alcohol drinking pattern in adulthood remains obscure. We studied the expression of SHH and components of respective signaling cascade [PTCH receptor (Patched), SMO co-receptor (Smoothened) and downstream transcriptional factor Glioma-associated oncogene (GLI)] during early abstinence in brain regions of rats demonstrating different drinking patterns in intermittent access two-bottle choice paradigm (IA2BC). Male Wistar rats were subjected to twenty 24-h sessions of free access to two-bottle choice (water or 20% ethanol) with 24-h withdrawal periods (water only). Control animals had access to water only. Quantitative PCR and western blotting were used to assess transcript and protein levels in the brain, respectively. During the course of the IA2BC, one part of animals demonstrated gradual escalation from low to high alcohol intake and preference of alcohol over water (group I), while the other one consumed alcohol at stable high level (group II) (Peregud et al., 2021). Three days after the last drinking session, PTCH mRNA elevated in the hippocampus of group I rats as compared to the control group. However, SHH, SMO and GLI mRNA levels in the hippocampus did not change. The protein content of PTCH in the hippocampus of group I rats was higher as compared to both control and group II. PTCH elevation is a known marker of SHH cascade activity. Thus, activated hippocampal SHH signaling cascade is a hallmark of rats demonstrating gradual escalation of alcohol intake in the IA2BC procedure.

Effects of advanced maternal age and acute prenatal alcohol exposure on mouse offspring growth and craniofacial phenotype

BACKGROUND

Prenatal alcohol exposure (PAE) can result in developmental defects that include growth restriction, craniofacial anomalies, and cognitive behavioral deficits, though the presence and severity of these adverse outcomes can vary dramatically among exposed individuals. Preclinical animal models have demonstrated that the dose and timing of PAE account for much, but not all, of this phenotypic variation, suggesting that additional factors mitigate the effects of PAE. Here, we used a mouse model to investigate whether maternal age modulates the effects of PAE on the severity and variation in offspring growth and craniofacial outcomes.

METHODS

Nulliparous C57BL/6N dams received either an intraperitoneal injection of ethanol (EtOH) or vehicle solution on gestational day 7.5. Dams were divided into four groups: (1) EtOH-treated young dams (6 to 10 weeks); (2) control young dams; (3) EtOH-treated old dams (6 to 7 months); and (4) old control dams. Neonate offspring growth restriction was measured through body mass and organ-to-body mass ratios, while skeletal craniofacial features were imaged using micro-CT and analyzed for size, shape, and variation.

RESULTS

PAE and advanced maternal age each increased the risk of low birthweight and growth restriction in offspring, but these factors in combination changed the nature of the growth restriction. Similarly, both PAE and advanced maternal age individually caused changes to craniofacial morphology such as smaller skull size, dysmorphic skull shape, and greater skull shape variation and asymmetry. Interestingly, while the combination of PAE and advanced maternal age did not affect mean skull shape or size, it significantly increased the variation and asymmetry of those measures.

CONCLUSION

Our results indicate that maternal age modulates the effects of PAE, but that the effects of this combination on offspring outcomes are more complex than simply scaling the effects of either factor.

Teratogenic effect of isotretinoin in both fertile females and males (Review)

Isotretinoin is an oral derivate of vitamin A that has been used since 1982 for the treatment of multiple dermatologic conditions such as severe acne, rosacea, scarring alopecia, ichthyosis or non-melanoma skin cancer prophylaxis. The recommended dose is 0.5-1 mg/kg/day for a period of 4-6 months in sebaceous gland pathologies. There are many adverse effects caused by isotretinoin but by far the most important is the teratogenicity induced by this drug which is estimated to have a 20-35% risk to infants that are exposed to isotretinoin in utero and includes numerous congenital defects such as craniofacial defects, cardiovascular and neurological malformations or thymic disorders. Isotretinoin induces apoptosis and cell cycle arrest in human sebocytes, emphasizing these as processes associated with its teratogenic effect. The aim of this review is to analyze the latest literature data regarding the teratogenic effect of isotretinoin for both fertile females and males and its biological effects underlying the occurrence of congenital malformations under the influence of isotretinoin.

Bioinformatics analysis of candidate genes involved in ethanol-induced microtia pathogenesis based on a human genome database: GeneCards

OBJECTIVE

Ethanol used by women during pregnancy increases the risk for microtia in the foetus. Traditionally, laboratory experiments and Mouse Genome Informatics (MGI) have been used to explore microtia pathogenesis. The aim of this study was to screen and verify hub genes involved in ethanol-induced microtia and to explore the potential molecular mechanisms.

METHODS

Overlapping genes related to ethanol and microtia were acquired from the GeneCards database and filtered by confidence score. These genes were further analysed via bioinformatics. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis results were visualized with the clusterProfiler R package. A protein-protein interaction (PPI) network was constructed based on data from the Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) database.

RESULTS

Overall, 41 genes related to both ethanol and microtia were identified. The genes most relevant to ethanol-induced microtia pathogenesis included FGFR-2, FGFR-3, FGF-8, TP53, IGF1, SHH, CTNNB1, and PAX6, among others. Most genes were strongly enriched for tissue and organ development in GO analysis. Additionally, many genes were enriched in the Ras, FoxO, MAPK, and PI3K-Akt signalling pathways in KEGG analysis.

CONCLUSIONS

Bioinformatics analysis was conducted on genes currently known to be related to ethanol-induced microtia pathogenesis. We propose that mechanisms involving FGF-family genes, TP53, IGF1 and SHH contribute significantly to ethanol-induced microtia and the accompanying malformation of other structures.

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.

The Special Developmental Biology of Craniofacial Tissues Enables the Understanding of Oral and Maxillofacial Physiology and Diseases

Maxillofacial hard tissues have several differences compared to bones of other localizations of the human body. These could be due to the different embryological development of the jaw bones compared to the extracranial skeleton. In particular, the immigration of neuroectodermally differentiated cells of the cranial neural crest (CNC) plays an important role. These cells differ from the mesenchymal structures of the extracranial skeleton. In the ontogenesis of the jaw bones, the development via the intermediate stage of the pharyngeal arches is another special developmental feature. The aim of this review was to illustrate how the development of maxillofacial hard tissues occurs via the cranial neural crest and pharyngeal arches, and what significance this could have for relevant pathologies in maxillofacial surgery, dentistry and orthodontic therapy. The pathogenesis of various growth anomalies and certain syndromes will also be discussed.

Prenatal Alcohol Exposure and the Facial Phenotype in Adolescents: A Study Based on Meconium Ethyl Glucuronide

Here, we explore the effects of prenatal alcohol exposure (PAE) in adolescence. We investigated associations between meconium ethyl glucoronide (EtG) and facial malformation. For 129 children (66/63 male/female; M = 13.3, SD = 0.32, 12–14 years), PAE was implemented by newborn meconium EtG and maternal self-reports during the third trimester. Cognitive development was operationalized by standardized scores (WISC V). The EtG cut-off values were set at ≥10 ng/g (n = 32, 24.8% EtG10+) and ≥112 ng/g (n = 20, 15.5% EtG112+). The craniofacial shape was measured using FAS Facial Photographic Analysis Software. EtG10+− and EtG112+-affected children exhibited a shorter palpebral fissure length (p = 0.031/p = 0.055). Lip circularity was smaller in EtG112+-affected children (p = 0.026). Maternal self-reports were not associated (p > 0.164). Lip circularity correlated with fluid reasoning (EtG10+ p = 0.031; EtG112+ p = 0.298) and working memory (EtG10+ p = 0.084; EtG112+ p = 0.144). The present study demonstrates visible effects of the facial phenotype in exposed adolescents. Facial malformation was associated with a child’s cognitive performance in the alcohol-exposed group. The EtG biomarker was a better predictor than maternal self-reports.

Glutathione Protects the Developing Heart from Defects and Global DNA Hypomethylation Induced by Prenatal Alcohol Exposure

BACKGROUND

Fetal alcohol spectrum disorder (FASD) is caused by prenatal alcohol exposure (PAE), the intake of ethanol (C2 H5 OH) during pregnancy. Features of FASD cover a range of structural and functional defects including congenital heart defects (CHDs). Folic acid and choline, contributors of methyl groups to one-carbon metabolism (OCM), prevent CHDs in humans. Using our avian model of FASD, we have previously reported that betaine, another methyl donor downstream of choline, prevents CHDs. The CHD preventions are substantial but incomplete. Ethanol causes oxidative stress as well as depleting methyl groups for OCM to support DNA methylation and other epigenetic alterations. To identify more compounds that can safely and effectively prevent CHDs and other effects of PAE, we tested glutathione (GSH), a compound that regulates OCM and is known as a "master antioxidant."

METHODS/RESULTS

Quail embryos injected with a single dose of ethanol at gastrulation exhibited congenital defects including CHDs similar to those identified in FASD individuals. GSH injected simultaneously with ethanol not only prevented CHDs, but also improved survival and prevented other PAE-induced defects. Assays of hearts at 8 days (HH stage 34) of quail development, when the heart normally has developed 4-chambers, showed that this single dose of PAE reduced global DNA methylation. GSH supplementation concurrent with PAE normalized global DNA methylation levels. The same assays performed on quail hearts at 3 days (HH stage 19-20) of development, showed no difference in global DNA methylation between controls, ethanol-treated, GSH alone, and GSH plus ethanol-treated cohorts.

CONCLUSIONS

GSH supplementation shows promise to inhibit effects of PAE by improving survival, reducing the incidence of morphological defects including CHDs, and preventing global hypomethylation of DNA in heart tissues.

Maternal alcohol consumption and risk of offspring with congenital malformation: the Japan Environment and Children's Study

BACKGROUND

The association between fetal exposure to alcohol and congenital structural disorders remains inconclusive. The present study searched for relationships between maternal alcohol consumption during pregnancy and the risk of congenital malformations.

METHODS

We evaluated the fixed dataset of a large national birth cohort study including 73,595 mothers with a singleton live birth. Information regarding the alcohol consumption of mothers was obtained from self-reported questionnaires. Physicians assessed for 6 major congenital malformations (congenital heart defects [CHDs], male genital abnormalities, limb defects, cleft lip and/or cleft palate [orofacial clefts (OFC)], severe brain abnormalities, and gastrointestinal obstructions) up to 1 month after birth. Multiple logistic regression analysis was performed to identify associations between maternal alcohol consumption during pregnancy and each malformation.

RESULTS

The prevalence of maternal drinking in early pregnancy and until the second/third trimester was 46.6% and 2.8%, respectively. The onset of CHD was inversely associated with mothers who quit drinking during early pregnancy (OR 0.85, 95% CI 0.74-0.98). There was no remarkable impact of maternal drinking habit status on the other congenital malformations after adjustment for covariates.

CONCLUSIONS

Maternal alcohol consumption during pregnancy, even in early pregnancy, displayed no significant adverse impact on congenital malformations of interest.

IMPACT

This large-scale Japanese cohort study revealed that no teratogenic associations were found between maternal retrospective reports of periconceptional alcohol consumption and congenital malformations after adjustment for covariates. This is the first nationwide birth cohort study in Japan to assess the effect of maternal alcohol consumption during pregnancy on major congenital malformations. Our finding indicated that maternal low-to-moderate alcohol consumption during pregnancy, even in early pregnancy, displayed no significant adverse impact on congenital heart defects, male genital abnormalities, limb defects, orofacial clefts, severe brain abnormalities, or gastrointestinal obstructions.

Mitochondrial dysfunction interferes with neural crest specification through the FoxD3 transcription factor

The neural crest is an important group of cells with pluripotency and migratory ability that is crucially involved in tissue and cell specification during development. Craniofacial shaping, sensory neurons, body asymmetry, and pigmentation are linked to neural crest functionality. Despite its prominent role in embryogenesis, neural crest specification as well as the possible part mitochondria play in such a process remains unclarified. Mitochondria are important organelles not only for respiration, but also for regulation of cell proliferation, differentiation and death. Modulation of mitochondrial fitness and depletion of mitochondrial ATP synthesis has been shown to down-regulate Wnt signaling, both in vitro and in vivo. Since Wnt signaling is one of the crucial players during neural crest induction/specification, we hypothesized a signaling cascade connecting mitochondria to embryonic development and neural crest migration and differentiation. Here, by using pharmacological and genetic modulators of mitochondrial function, we provide evidence that a crosstalk between mitochondrial energy homeostasis and Wnt signaling is important in the development of neural crest-derived tissues. Furthermore, our results highlight the possibility to modulate neural crest cell specification by tuning mitochondrial metabolism via FoxD3, an important transcription factor that is regulated by Wnt. FoxD3 ensures the correct embryonic development and contributes to the maintenance of cell stemness and to the induction of epithelial-to-mesenchymal transition. In summary, our work offers new insights into the molecular mechanism of action of FoxD3 and demonstrates that mitochondrial fitness is linked to the regulation of this important transcription factor via Wnt signaling in the context of neural crest specification.

Murine Models for the Study of Fetal Alcohol Spectrum Disorders: An Overview

Prenatal alcohol exposure is associated to different physical, behavioral, cognitive, and neurological impairments collectively known as fetal alcohol spectrum disorder. The underlying mechanisms of ethanol toxicity are not completely understood. Experimental studies during human pregnancy to identify new diagnostic biomarkers are difficult to carry out beyond genetic or epigenetic analyses in biological matrices. Therefore, animal models are a useful tool to study the teratogenic effects of alcohol on the central nervous system and analyze the benefits of promising therapies. Animal models of alcohol spectrum disorder allow the analysis of key variables such as amount, timing and frequency of ethanol consumption to describe the harmful effects of prenatal alcohol exposure. In this review, we aim to synthetize neurodevelopmental disabilities in rodent fetal alcohol spectrum disorder phenotypes, considering facial dysmorphology and fetal growth restriction. We examine the different neurodevelopmental stages based on the most consistently implicated epigenetic mechanisms, cell types and molecular pathways, and assess the advantages and disadvantages of murine models in the study of fetal alcohol spectrum disorder, the different routes of alcohol administration, and alcohol consumption patterns applied to rodents. Finally, we analyze a wide range of phenotypic features to identify fetal alcohol spectrum disorder phenotypes in murine models, exploring facial dysmorphology, neurodevelopmental deficits, and growth restriction, as well as the methodologies used to evaluate behavioral and anatomical alterations produced by prenatal alcohol exposure in rodents.