Bladder Cancer Progression Is Suppressed Through the Heart and Neural Crest Derivatives Expressed 2-Antisense RNA 1/microRNA-93-5p/Defective in Cullin Neddylation 1 Domain Containing 3 Axis

MicroRNAs (miRNAs) are critical in progression of bladder cancer (BCa). miRNA-93-5p is increased in cancers and is positively correlated with an unfavorable prognosis. But its effects on BCa remain rarely understood. This investigation aimed to dig out miRNA-93-5p affecting biological behaviors of BCa. In this research, mRNA and protein expression in cancer cells were assessed via quantitative real-time polymerase chain reaction (qRT-PCR) and western blot. Cell Counting Kit-8 (CCK-8), colony formation, scratch healing, and transwell assays were utilized to analyze cancer cell viability, colony-forming, migration, and invasion, respectively. Bioinformatics analysis predicted upstream regulatory genes and downstream target genes of miRNA-93-5p, with the targeting relationship being verified through a dual-luciferase assay. The BCa xenograft model in nude mice further investigated the effect of miRNA-93-5p and AND2-AS1 on tumor size and quality, and validated the relationship between HAND2-AS1/miRNA-93-5p/DCUN1D3. Our results displayed that miRNA-93-5p was increased in BCa cell lines. Knockdown miRNA-93-5p constrained BCa cell malignant phenotypes. HAND2-AS1 targeted miRNA-93-5p, thus restraining malignant progression of BCa cells. DCUN1D3 was found downstream of miRNA-93-5p. miRNA-93-5p modulated proliferation, migration, and invasion of BCa cells by targeting DCUN1D3. In vivo experiments disclosed that forced expression of lncRNA HAND2-AS1, and inhibited miRNA-93-5p regressed tumor growth. Meanwhile, the same as the results of cell experiments, the expression of miRNA-93-5p was downregulated, and DCUN1D3 expression was advanced in tumor tissues. To conclude, lncRNA HAND2-AS1 exerted anti-tumor effects and regulated BCa cell proliferation, invasion, and migration by targeting miRNA-93-5p/DCUN1D3.

POLR1A variants underlie phenotypic heterogeneity in craniofacial, neural, and cardiac anomalies

Heterozygous pathogenic variants in POLR1A, which encodes the largest subunit of RNA Polymerase I, were previously identified as the cause of acrofacial dysostosis, Cincinnati-type. The predominant phenotypes observed in the cohort of 3 individuals were craniofacial anomalies reminiscent of Treacher Collins syndrome. We subsequently identified 17 additional individuals with 12 unique heterozygous variants in POLR1A and observed numerous additional phenotypes including neurodevelopmental abnormalities and structural cardiac defects, in combination with highly prevalent craniofacial anomalies and variable limb defects. To understand the pathogenesis of this pleiotropy, we modeled an allelic series of POLR1A variants in vitro and in vivo. In vitro assessments demonstrate variable effects of individual pathogenic variants on ribosomal RNA synthesis and nucleolar morphology, which supports the possibility of variant-specific phenotypic effects in affected individuals. To further explore variant-specific effects in vivo, we used CRISPR-Cas9 gene editing to recapitulate two human variants in mice. Additionally, spatiotemporal requirements for Polr1a in developmental lineages contributing to congenital anomalies in affected individuals were examined via conditional mutagenesis in neural crest cells (face and heart), the second heart field (cardiac outflow tract and right ventricle), and forebrain precursors in mice. Consistent with its ubiquitous role in the essential function of ribosome biogenesis, we observed that loss of Polr1a in any of these lineages causes cell-autonomous apoptosis resulting in embryonic malformations. Altogether, our work greatly expands the phenotype of human POLR1A-related disorders and demonstrates variant-specific effects that provide insights into the underlying pathogenesis of ribosomopathies.

Augmentation of bone morphogenetic protein signaling in cranial neural crest cells in mice deforms skull base due to premature fusion of intersphenoidal synchondrosis

Craniofacial anomalies (CFAs) are a diverse group of disorders affecting the shapes of the face and the head. Malformation of the cranial base in humans leads CFAs, such as midfacial hypoplasia and craniosynostosis. These patients have significant burdens associated with breathing, speaking, and chewing. Invasive surgical intervention is the current primary option to correct these structural deficiencies. Understanding molecular cellular mechanism for craniofacial development would provide novel therapeutic options for CFAs. In this study, we found that enhanced bone morphogenetic protein (BMP) signaling in cranial neural crest cells (NCCs) (P0-Cre;caBmpr1a mice) causes premature fusion of intersphenoid synchondrosis (ISS) resulting in leading to short snouts and hypertelorism. Histological analyses revealed reduction of proliferation and higher cell death in ISS at postnatal day 3. We demonstrated to prevent the premature fusion of ISS in P0-Cre;caBmpr1a mice by injecting a p53 inhibitor Pifithrin-α to the pregnant mother from E15.5 to E18.5, resulting in rescue from short snouts and hypertelorism. We further demonstrated to prevent premature fusion of cranial sutures in P0-Cre;caBmpr1a mice by injecting Pifithrin-α through E8.5 to E18.5. These results suggested that enhanced BMP-p53-induced cell death in cranial NCCs causes premature fusion of ISS and sutures in time-dependent manner.

Neuroblastoma: When differentiation goes awry

Neuroblastoma is a leading cause of cancer-related death in children. Accumulated data suggest that differentiation arrest of the neural-crest-derived sympathoadrenal lineage contributes to neuroblastoma formation. The developmental arrest of these cell types explains many biological features of the disease, including its cellular heterogeneity, mutational spectrum, spontaneous regression, and response to drugs that induce tumor cell differentiation. In this review, we provide evidence that supports the notion that arrested neural-crest-derived progenitor cells give rise to neuroblastoma and discuss how this concept could be exploited for clinical management of the disease.

Bcar1/p130Cas is essential for ventricular development and neural crest cell remodelling of the cardiac outflow tract

AIMS

The adapter protein p130Cas, encoded by the Bcar1 gene, is a key regulator of cell movement, adhesion, and cell cycle control in diverse cell types. Bcar1 constitutive knockout mice are embryonic lethal by embryonic days (E) 11.5-12.5, but the role of Bcar1 in embryonic development remains unclear. Here, we investigated the role of Bcar1 specifically in cardiovascular development and defined the cellular and molecular mechanisms disrupted following targeted Bcar1 deletions.

METHODS AND RESULTS

We crossed Bcar1 floxed mice with Cre transgenic lines allowing for cell-specific knockout either in smooth muscle and early cardiac tissues (SM22-Cre), mature smooth muscle cells (smMHC-Cre), endothelial cells (Tie2-Cre), second heart field cells (Mef2c-Cre), or neural crest cells (NCC) (Pax3-Cre) and characterized these conditional knock outs using a combination of histological and molecular biology techniques. Conditional knockout of Bcar1 in SM22-expressing smooth muscle cells and cardiac tissues (Bcar1SM22KO) was embryonically lethal from E14.5-15.5 due to severe cardiovascular defects, including abnormal ventricular development and failure of outflow tract (OFT) septation leading to a single outflow vessel reminiscent of persistent truncus arteriosus. SM22-restricted loss of Bcar1 was associated with failure of OFT cushion cells to undergo differentiation to septal mesenchymal cells positive for SMC-specific α-actin, and disrupted expression of proteins and transcription factors involved in epithelial-to-mesenchymal transformation (EMT). Furthermore, knockout of Bcar1 specifically in NCC (Bcar1PAX3KO) recapitulated part of the OFT septation and aortic sac defects seen in the Bcar1SM22KO mutants, indicating a cell-specific requirement for Bcar1 in NCC essential for OFT septation. In contrast, conditional knockouts of Bcar1 in differentiated smooth muscle, endothelial cells, and second heart field cells survived to term and were phenotypically normal at birth and postnatally.

CONCLUSION

Our work reveals a cell-specific requirement for Bcar1 in NCC, early myogenic and cardiac cells, essential for OFT septation, myocardialization and EMT/cell cycle regulation and differentiation to myogenic lineages.

Human embryonic stem cell-derived neural crest model unveils CD55 as a cancer stem cell regulator for therapeutic targeting in MYCN-amplified neuroblastoma

BACKGROUND

Neuroblastoma (NB) is a common childhood malignant tumor of neural crest (NC) origin with remarkable heterogeneity in outcomes. Amplification of the oncogene MYCN is strongly associated with highly malignant behaviour and poor prognosis.

METHODS

This study aims to use a human embryonic stem cell (hESC)-derived NC model to identify novel downstream effectors of MYCN that can be potentially used as prognostic marker and/or therapeutic target.

RESULTS

We show that MYCN-driven NB derived from human neural crest cells (hNCCs) recapitulate the pathological and molecular features of MYCN-amplified neuroblastoma (MNA-NB). By using this platform, we identify a group of 14 surface protein-encoding genes that are associated with MYCN expression level in MNA-NB. Among these genes, high CD55 expression is correlated with poor survival in MNA-NB but not in non-MNA-NB. Furthermore, CD55 promotes tumorigenesis, tumor growth, and cancer stemness in MNA-NB cell lines (MNA-NBL) through regulating the JNK pathway. Mechanistically, MYCN binds to both canonical and noncanonical E-boxes on the promoter of CD55 to regulate its transcriptional expression. Finally, neutralizing antibody targeting CD55 significantly attenuates cancer stemness, suppresses tumor growth, and improves survival exclusively in MNA-NBL-inoculated mice.

CONCLUSION

MYCN shapes CD55 into a cancer stem cell regulator which represents a prognostic marker and therapeutic target of MNA-NB. The hESC-derived NC model serves as a valuable platform for investigating NB initiation and progression and developing potential therapeutic targets.

Neural Crest Stem Cells in Juvenile Angiofibromas

The etiology of juvenile angiofibroma (JA) has been a controversial topic for more than 160 years. Numerous theories have been proposed to explain this rare benign neoplasm arising predominately in adolescent males, focusing mainly on either the vascular or fibrous component. To assess our hypothesis of JA’s being a malformation arising from neural crest cells/remnants of the first branchial arch plexus, we performed immunohistochemical analyses of neural crest stem cells (NCSC) and epithelial-mesenchymal transition (EMT) candidates. Immunoexpression of the NCSC marker CD271^p75 was observed in all investigated JA’s (n = 22), mainly around the pathological vessels. Close to CD271^p75-positive cells, high MMP3-staining was also observed. Additionally, from one JA with sufficient material, RT-qPCR identified differences in the expression pattern of PDGFRβ, MMP2 and MMP3 in MACS^®-separated CD271^p75positive vs. CD271^p75 negative cell fractions. Our results, together with the consideration of the literature, provide evidence that JA’s represent a malformation within the first branchial arch artery/plexus remnants deriving from NCSC. This theory would explain the typical site of tumor origin as well as the characteristic tumor blood supply, whereas the process of EMT provides an explanation for the vascular and fibrous tumor component.

The Somatic Mutation Paradigm in Congenital Malformations: Hirschsprung Disease as a Model

Patients with Hirschsprung disease (HSCR) do not always receive a genetic diagnosis after routine screening in clinical practice. One of the reasons for this could be that the causal mutation is not present in the cell types that are usually tested—whole blood, dermal fibroblasts or saliva—but is only in the affected tissue. Such mutations are called somatic, and can occur in a given cell at any stage of development after conception. They will then be present in all subsequent daughter cells. Here, we investigated the presence of somatic mutations in HSCR patients. For this, whole-exome sequencing and copy number analysis were performed in DNA isolated from purified enteric neural crest cells (ENCCs) and blood or fibroblasts of the same patient. Variants identified were subsequently validated by Sanger sequencing. Several somatic variants were identified in all patients, but causative mutations for HSCR were not specifically identified in the ENCCs of these patients. Larger copy number variants were also not found to be specific to ENCCs. Therefore, we believe that somatic mutations are unlikely to be identified, if causative for HSCR. Here, we postulate various modes of development following the occurrence of a somatic mutation, to describe the challenges in detecting such mutations, and hypothesize how somatic mutations may contribute to ‘missing heritability’ in developmental defects.

Evolutionary predictability of genetic versus nongenetic resistance to anticancer drugs in melanoma

Therapy resistance arises from heterogeneous drug-tolerant persister cells or minimal residual disease (MRD) through genetic and nongenetic mechanisms. A key question is whether specific molecular features of the MRD ecosystem determine which of these two distinct trajectories will eventually prevail. We show that, in melanoma exposed to mitogen-activated protein kinase therapeutics, emergence of a transient neural crest stem cell (NCSC) population in MRD concurs with the development of nongenetic resistance. This increase relies on a glial cell line-derived neurotrophic factor-dependent signaling cascade, which activates the AKT survival pathway in a focal adhesion kinase (FAK)-dependent manner. Ablation of the NCSC population through FAK inhibition delays relapse in patient-derived tumor xenografts. Strikingly, all tumors that ultimately escape this treatment exhibit resistance-conferring genetic alterations and increased sensitivity to extracellular signal-regulated kinase inhibition. These findings identify an approach that abrogates the nongenetic resistance trajectory in melanoma and demonstrate that the cellular composition of MRD deterministically imposes distinct drug resistance evolutionary paths.

Puma- and Caspase9-mediated apoptosis is dispensable for p53-driven neural crest-based developmental defects

Inappropriate activation of the p53 transcription factor is thought to contribute to the developmental phenotypes in a range of genetic syndromes. Whether p53 activation drives these developmental phenotypes by triggering apoptosis, cell cycle arrest, or other p53 cellular responses, however, has remained elusive. As p53 hyperactivation in embryonic neural crest cells (NCCs) drives a number of phenotypes, including abnormal craniofacial and neuronal development, we investigate the basis for p53 action in this context. We show that p53-driven developmental defects are associated with the induction of a robust pro-apoptotic transcriptional signature. Intriguingly, however, deleting Puma or Caspase9, which encode key components of the intrinsic apoptotic pathway, does not rescue craniofacial, neuronal or pigmentation defects triggered by p53 hyperactivation in NCCs. Immunostaining analyses for two key apoptosis markers confirm that deleting Puma or Caspase9 does indeed impair p53-hyperactivation-induced apoptosis in NCCs. Furthermore, we demonstrate that p53 hyperactivation does not trigger a compensatory dampening of cell cycle progression in NCCs upon inactivation of apoptotic pathways. Together, our results indicate that p53-driven craniofacial, neuronal and pigmentation defects can arise in the absence of apoptosis and cell cycle arrest, suggesting that p53 hyperactivation can act via alternative pathways to trigger developmental phenotypes.

Cutaneous Cephalic Neurocristic Hamartoma on the Head With Melanocytic, Cartilage, Blood Vessel, Neural, and Bony Tissue

ABSTRACT

We report on a congenital tumor of the face and scalp in a male newborn, histologically proven to contain melanocytes, cartilage, and bone, vascular, and neural tissue as part of a pigmented congenital tumor. Thus, this tumor was classified as a cutaneous cephalic neurocristic hamartoma.

Somatic mutations and single-cell transcriptomes reveal the root of malignant rhabdoid tumours

Malignant rhabdoid tumour (MRT) is an often lethal childhood cancer that, like many paediatric tumours, is thought to arise from aberrant fetal development. The embryonic root and differentiation pathways underpinning MRT are not firmly established. Here, we study the origin of MRT by combining phylogenetic analyses and single-cell mRNA studies in patient-derived organoids. Comparison of somatic mutations shared between cancer and surrounding normal tissues places MRT in a lineage with neural crest-derived Schwann cells. Single-cell mRNA readouts of MRT differentiation, which we examine by reverting the genetic driver mutation underpinning MRT, SMARCB1 loss, suggest that cells are blocked en route to differentiating into mesenchyme. Quantitative transcriptional predictions indicate that combined HDAC and mTOR inhibition mimic MRT differentiation, which we confirm experimentally. Our study defines the developmental block of MRT and reveals potential differentiation therapies.

Gestational folate deficiency alters embryonic gene expression and cell function

Folic acid is a nutrient essential for embryonic development. Folate deficiency can cause embryonic lethality or neural tube defects and orofacial anomalies. Folate receptor 1 (Folr1) is a folate binding protein that facilitates the cellular uptake of dietary folate. To better understand the biological processes affected by folate deficiency, gene expression profiles of gestational day 9.5 (gd9.5) Folr1^-/- embryos were compared to those of gd9.5 Folr1^+/+ embryos. The expression of 837 genes/ESTs was found to be differentially altered in Folr1^-/- embryos, relative to those observed in wild-type embryos. The 837 differentially expressed genes were subjected to Ingenuity Pathway Analysis. Among the major biological functions affected in Folr1^-/- mice were those related to 'digestive system development/function', 'cardiovascular system development/function', 'tissue development', 'cellular development', and 'cell growth and differentiation', while the major canonical pathways affected were those associated with blood coagulation, embryonic stem cell transcription and cardiomyocyte differentiation (via BMP receptors). Cellular proliferation, apoptosis and migration were all significantly affected in the Folr1^-/- embryos. Cranial neural crest cells (NCCs) and neural tube explants, grown under folate-deficient conditions, exhibited marked reduction in directed migration that can be attributed, in part, to an altered cytoskeleton caused by perturbations in F-actin formation and/or assembly. The present study revealed that several developmentally relevant biological processes were compromised in Folr1^-/- embryos.

Quantitative proteomics reveal lineage-specific protein profiles in iPSC-derived Marfan syndrome smooth muscle cells

Marfan syndrome (MFS) is a connective tissue disorder caused by mutations in the FBN1 gene that produces wide disease phenotypic variability. The lack of ample genotype-phenotype correlation hinders translational study development aimed at improving disease prognosis. In response to this need, an induced pluripotent stem cell (iPSC) disease model has been used to test patient-specific cells by a proteomic approach. This model has the potential to risk stratify patients to make clinical decisions, including timing for surgical treatment. The regional propensity for aneurysm formation in MFS may be related to distinct smooth muscle cell (SMC) embryologic lineages. Thus, peripheral blood mononuclear cell (PBMC)-derived induced pluripotent stem cells (iPSC) were differentiated into lateral mesoderm (LM, aortic root) and neural crest (NC, ascending aorta/transverse arch) SMC lineages to model MFS aortic pathology. Isobaric Tags for Relative and Absolute Quantitation (iTRAQ) proteomic analysis by tandem mass spectrometry was applied to profile LM and NC iPSC SMCs from four MFS patients and two healthy controls. Analysis revealed 45 proteins with lineage-dependent expression in MFS patients, many of which were specific to diseased samples. Single protein-level data from both iPSC SMCs and primary MFS aortic root aneurysm tissue confirmed elevated integrin αV and reduced MRC2 in clinical disease specimens, validating the iPSC iTRAQ findings. Functionally, iPSC SMCs exhibited defective adhesion to a variety of extracellular matrix proteins, especially laminin-1 and fibronectin, suggesting altered cytoskeleton dynamics. This study defines the aortic embryologic origin-specific proteome in a validated iPSC SMC model to identify novel protein markers associated with MFS aneurysm phenotype. Translating iPSC findings into clinical aortic aneurysm tissue samples highlights the potential for iPSC-based methods to model MFS disease for mechanistic studies and therapeutic discovery in vitro.

Ocular measurements in fetal alcohol spectrum disorders

Fetal alcohol spectrum disorders (FASD) describe a range of physical, behavioral, and neurologic deficits in individuals exposed to alcohol prenatally. Reduced palpebral fissure length is one of the cardinal facial features of FASD. However, other ocular measurements have not been studied extensively in FASD. Using the Fetal Alcohol Syndrome Epidemiologic Research (FASER) database, we investigated how inner canthal distance (ICD), interpupillary distance (IPD), and outer canthal distance (OCD) centiles differed between FASD and non-FASD individuals. We compared ocular measurement centiles in children with FASD to non-FASD individuals and observed reductions in all three centiles for ICD, IPD, and OCD. However, when our non-FASD children who had various forms of growth deficiency (microcephaly, short-stature, or underweight) were compared to controls, we did not observe a similar reduction in ocular measurements. This suggests that reductions in ocular measurements are a direct effect of alcohol on ocular development independent of its effect on growth parameters, which is consistent with animal models showing a negative effect of alcohol on developing neural crest cells. Interpupillary distance centile appeared to be the most significantly reduced ocular measure we evaluated, suggesting it may be a useful measure to be considered in the diagnosis of FASD.

Paired Box 9 (PAX9), the RNA polymerase II transcription factor, regulates human ribosome biogenesis and craniofacial development

Dysregulation of ribosome production can lead to a number of developmental disorders called ribosomopathies. Despite the ubiquitous requirement for these cellular machines used in protein synthesis, ribosomopathies manifest in a tissue-specific manner, with many affecting the development of the face. Here we reveal yet another connection between craniofacial development and making ribosomes through the protein Paired Box 9 (PAX9). PAX9 functions as an RNA Polymerase II transcription factor to regulate the expression of proteins required for craniofacial and tooth development in humans. We now expand this function of PAX9 by demonstrating that PAX9 acts outside of the cell nucleolus to regulate the levels of proteins critical for building the small subunit of the ribosome. This function of PAX9 is conserved to the organism Xenopus tropicalis, an established model for human ribosomopathies. Depletion of pax9 leads to craniofacial defects due to abnormalities in neural crest development, a result consistent with that found for depletion of other ribosome biogenesis factors. This work highlights an unexpected layer of how the making of ribosomes is regulated in human cells and during embryonic development.

From Tank to Treatment: Modeling Melanoma in Zebrafish

Melanoma is the deadliest form of skin cancer and one of few cancers with a growing incidence. A thorough understanding of its pathogenesis is fundamental to developing new strategies to combat mortality and morbidity. Zebrafish—due in large part to their tractable genetics, conserved pathways, and optical properties—have emerged as an excellent system to model melanoma. Zebrafish have been used to study melanoma from a single tumor initiating cell, through metastasis, remission, and finally into relapse. In this review, we examine seminal zebrafish studies that have advanced our understanding of melanoma.

Neural crest-derived tumor neuroblastoma and melanoma share 1p13.2 as susceptibility locus that shows a long-range interaction with the SLC16A1 gene

Neuroblastoma (NB) and malignant cutaneous melanoma (CMM) are neural crest cells (NCC)-derived tumors and may have a shared genetic basis, but this has not been investigated systematically by genome-wide association studies (GWAS). We took a three-staged approach to conduct cross-disease meta-analysis of GWAS for NB and CMM (2101 NB cases and 4202 controls; 12 874 CMM cases and 23 203 controls) to identify shared loci. Findings were replicated in 1403 NB cases and 1403 controls of European ancestry and in 636 NB, 508 CMM cases and 2066 controls of Italian origin. We found a cross-association at locus 1p13.2 (rs2153977, odds ratio = 0.91, P = 5.36 × 10-8). We also detected a suggestive (P < 10-7) NB-CMM cross-association at 2q37.1 with opposite effect on cancer risk. Pathway analysis of 110 NB-CMM risk loci with P < 10-4 demonstrated enrichment of biological processes such as cell migration, cell cycle, metabolism and immune response, which are essential of human NCC development, underlying both tumors. In vitro and in silico analyses indicated that the rs2153977-T protective allele, located in an NB and CMM enhancer, decreased expression of SLC16A1 via long-range loop formation and altered a T-box protein binding site. Upon depletion of SLC16A1, we observed a decrease of cellular proliferation and invasion in both NB and CMM cell lines, suggesting its role as oncogene. This is the largest study to date examining pleiotropy across two NC cell-derived tumors identifying 1p13.2 as common susceptibility locus for NB and CMM risk. We demonstrate that combining genome-wide association studies results across cancers with same origins can identify new loci common to neuroblastoma and melanoma arising from tissues which originate from neural crest cells. Our results also show 1p13.2 confer risk to neuroblastoma and melanoma by regulating SLC16A1.

Noncoding Microdeletion in Mouse Hgf Disrupts Neural Crest Migration into the Stria Vascularis, Reduces the Endocochlear Potential, and Suggests the Neuropathology for Human Nonsyndromic Deafness DFNB39

Hepatocyte growth factor (HGF) is a multifunctional protein that signals through the MET receptor. HGF stimulates cell proliferation, cell dispersion, neuronal survival, and wound healing. In the inner ear, levels of HGF must be fine-tuned for normal hearing. In mice, a deficiency of HGF expression limited to the auditory system, or an overexpression of HGF, causes neurosensory deafness. In humans, noncoding variants in HGF are associated with nonsyndromic deafness DFNB39 However, the mechanism by which these noncoding variants causes deafness was unknown. Here, we reveal the cause of this deafness using a mouse model engineered with a noncoding intronic 10 bp deletion (del10) in Hgf Male and female mice homozygous for del10 exhibit moderate-to-profound hearing loss at 4 weeks of age as measured by tone burst auditory brainstem responses. The wild type (WT) 80 mV endocochlear potential was significantly reduced in homozygous del10 mice compared with WT littermates. In normal cochlea, endocochlear potentials are dependent on ion homeostasis mediated by the stria vascularis (SV). Previous studies showed that developmental incorporation of neural crest cells into the SV depends on signaling from HGF/MET. We show by immunohistochemistry that, in del10 homozygotes, neural crest cells fail to infiltrate the developing SV intermediate layer. Phenotyping and RNAseq analyses reveal no other significant abnormalities in other tissues. We conclude that, in the inner ear, the noncoding del10 mutation in Hgf leads to developmental defects of the SV and consequently dysfunctional ion homeostasis and a reduction in the EP, recapitulating human DFNB39 nonsyndromic deafness.SIGNIFICANCE STATEMENT Hereditary deafness is a common, clinically and genetically heterogeneous neurosensory disorder. Previously, we reported that human deafness DFNB39 is associated with noncoding variants in the 3'UTR of a short isoform of HGF encoding hepatocyte growth factor. For normal hearing, HGF levels must be fine-tuned as an excess or deficiency of HGF cause deafness in mouse. Using a Hgf mutant mouse with a small 10 bp deletion recapitulating a human DFNB39 noncoding variant, we demonstrate that neural crest cells fail to migrate into the stria vascularis intermediate layer, resulting in a significantly reduced endocochlear potential, the driving force for sound transduction by inner ear hair cells. HGF-associated deafness is a neurocristopathy but, unlike many other neurocristopathies, it is not syndromic.

A Balanced Translocation in Kallmann Syndrome Implicates a Long Noncoding RNA, RMST, as a GnRH Neuronal Regulator

CONTEXT

Kallmann syndrome (KS) is a rare, genetically heterogeneous Mendelian disorder. Structural defects in KS patients have helped define the genetic architecture of gonadotropin-releasing hormone (GnRH) neuronal development in this condition.

OBJECTIVE

Examine the functional role a novel structural defect affecting a long noncoding RNA (lncRNA), RMST, found in a KS patient.

DESIGN

Whole genome sequencing, induced pluripotent stem cells and derived neural crest cells (NCC) from the KS patient were contrasted with controls.

SETTING

The Harvard Reproductive Sciences Center, Massachusetts General Hospital Center for Genomic Medicine, and Singapore Genome Institute.

PATIENT

A KS patient with a unique translocation, t(7;12)(q22;q24).

INTERVENTIONS/MAIN OUTCOME MEASURE/RESULTS

A novel translocation was detected affecting the lncRNA, RMST, on chromosome 12 in the absence of any other KS mutations. Compared with controls, the patient's induced pluripotent stem cells and NCC provided functional information regarding RMST. Whereas RMST expression increased during NCC differentiation in controls, it was substantially reduced in the KS patient's NCC coincident with abrogated NCC morphological development and abnormal expression of several "downstream" genes essential for GnRH ontogeny (SOX2, PAX3, CHD7, TUBB3, and MKRN3). Additionally, an intronic single nucleotide polymorphism in RMST was significantly implicated in a genome-wide association study associated with age of menarche.

CONCLUSIONS

A novel deletion in RMST implicates the loss of function of a lncRNA as a unique cause of KS and suggests it plays a critical role in the ontogeny of GnRH neurons and puberty.

The histone methyltransferase KMT2D, mutated in Kabuki syndrome patients, is required for neural crest cell formation and migration

Kabuki syndrome is an autosomal dominant developmental disorder with high similarities to CHARGE syndrome. It is characterized by a typical facial gestalt in combination with short stature, intellectual disability, skeletal findings and additional features like cardiac and urogenital malformations, cleft palate, hearing loss and ophthalmological anomalies. The major cause of Kabuki syndrome are mutations in KMT2D, a gene encoding a histone H3 lysine 4 (H3K4) methyltransferase belonging to the group of chromatin modifiers. Here we provide evidence that Kabuki syndrome is a neurocrestopathy, by showing that Kmt2d loss-of-function inhibits specific steps of neural crest (NC) development. Using the Xenopus model system, we find that Kmt2d loss-of-function recapitulates major features of Kabuki syndrome including severe craniofacial malformations. A detailed marker analysis revealed defects in NC formation as well as migration. Transplantation experiments confirm that Kmt2d function is required in NC cells. Furthermore, analyzing in vivo and in vitro NC migration behavior demonstrates that Kmt2d is necessary for cell dispersion but not protrusion formation of migrating NC cells. Importantly, Kmt2d knockdown correlates with a decrease in H3K4 monomethylation and H3K27 acetylation supporting a role of Kmt2d in the transcriptional activation of target genes. Consistently, using a candidate approach, we find that Kmt2d loss-of-function inhibits Xenopus Sema3F expression, and overexpression of Sema3F can partially rescue Kmt2d loss-of-function defects. Taken together, our data reveal novel functions of Kmt2d in multiple steps of NC development and support the hypothesis that major features of Kabuki syndrome are caused by defects in NC development.

Thalidomide leads to mandible hypoplasia through inhibiting angiogenesis and secondary hemorrhage in the fetal craniofacial region in rabbits

The effect of thalidomide on mandibular development is unclear. In this study, thalidomide was delivered to pregnant rabbits from the 8th to 14th day of gestation. Then, embryos were harvested for examination on the 16th day (GD16), 20th day (GD20) and 24th day (GD24) of gestation. The results showed obvious hemorrhage and hematoma on one side of the craniofacial region in 50 % of the thalidomide-treated embryos and obvious hemorrhage and hematoma on both sides of the craniofacial region in 50 % of the thalidomide-treated embryos at GD16. Histological examination showed soft tissues and mandible defects on the affected side of the maxillofacial region. The expression of Vegf-α, Ki67 and Sox9 on the affected side was significantly down-regulated in comparison to their expression on the unaffected side at GD20. There was also an obvious defect in the affected mandible, and the density of the skull and mandible was decreased compared to the unaffected side or the control group at GD24. These findings demonstrated that thalidomide may lead to hemorrhage and hematoma in the craniofacial region by inhibiting angiogenesis, resulting in the abnormal development of cranial neural crest cells that are involved in the normal development of the mandible in rabbits.

Perturbed development of cranial neural crest cells in association with reduced sonic hedgehog signaling underlies the pathogenesis of retinoic-acid-induced cleft palate

Cleft palate (CP) is one of the most common congenital craniofacial anomalies in humans and can be caused by either single or multiple genetic and environmental factor(s). With respect to environmental factors, excessive intake of vitamin A during early pregnancy is associated with increased incidence of CP in offspring both in humans and in animal models. Vitamin A is metabolized to retinoic acid (RA); however, the pathogenetic mechanism of CP caused by altered RA signaling during early embryogenesis is not fully understood. To investigate the detailed cellular and molecular mechanism of RA-induced CP, we administered all-trans RA to pregnant mice at embryonic day (E)8.5. In the RA-treated group, we observed altered expression of Sox10, which marks cranial neural crest cells (CNCCs). Disruption of Sox10 expression was also observed at E10.5 in the maxillary component of the first branchial arch, which gives rise to secondary palatal shelves. Moreover, we found significant elevation of CNCC apoptosis in RA-treated embryos. RNA-sequencing comparisons of RA-treated embryos compared to controls revealed alterations in Sonic hedgehog (Shh) signaling. More specifically, the expression of Shh and its downstream genes Ptch1 and Gli1 was spatiotemporally downregulated in the developing face of RA-treated embryos. Consistent with these findings, the incidence of CP in association with excessive RA signaling was reduced by administration of the Shh signaling agonist SAG (Smoothened agonist). Altogether, our results uncovered a novel mechanistic association between RA-induced CP with decreased Shh signaling and elevated CNCC apoptosis.

Exploring Shared Susceptibility between Two Neural Crest Cells Originating Conditions: Neuroblastoma and Congenital Heart Disease

In the past years, genome wide association studies (GWAS) have provided evidence that inter-individual susceptibility to diverse pathological conditions can reveal a common genetic architecture. Through the analysis of congenital heart disease (CHD) and neuroblastoma (NB) GWAS data, we aimed to dissect the genetic susceptibility shared between these conditions, which are known to arise from neural crest cell (NCC) migration or development abnormalities, via identification and functional characterization of common regions of association. Two loci (2q35 and 3q25.32) harbor single nucleotide polymorphisms (SNPs) that are associated at a p-value < 10^-3 with conotruncal malformations and ventricular septal defect respectively, as well as with NB. In addition, the lead SNP in 4p16.2 for atrial septal defect and the lead SNP in 3q25.32 for tetralogy of Fallot are less than 250 Kb distant from the lead SNPs for NB at the same genomic regions. Some of these shared susceptibility loci regulate the expression of relevant genes involved in NCC formation and developmental processes (such as BARD1, MSX1, and SHOX2) and are enriched in several epigenetic markers from NB and fetal heart cell lines. Although the clinical correlation between NB and CHD is unclear, our exploration of a possible common genetic basis between NB and a subset of cardiac malformations can help shed light on their shared embryological origin and pathogenetic mechanisms.

Alcohol-mediated calcium signals dysregulate pro-survival Snai2/PUMA/Bcl2 networks to promote p53-mediated apoptosis in avian neural crest progenitors

BACKGROUND

Prenatal alcohol exposure causes distinctive craniofacial anomalies that arise, in part, from the apoptotic elimination of neural crest (NC) progenitors that form the face. This vulnerability of NC to alcohol is puzzling as they normally express the transcriptional repressor Snail1/2 (in chick Snai2), which suppresses apoptosis and promotes their migration. Here, we investigate alcohol's impact upon Snai2 function.

METHODS

Chick cranial NC cells were treated with acute alcohol (52 mM, 2 hr). We evaluated NC migration, gene expression, proliferation, and apoptosis thereafter.

RESULTS

Transient alcohol exposure induced Snai2 (191% ± 23%; p = .003) and stimulated NC migration (p = .0092). An alcohol-induced calcium transient mediated this Snai2 induction, and BAPTA-AM blocked whereas ionomycin mimicked these pro-migratory effects. Alcohol suppressed CyclinD1 protein content (59.1 ± 12%, p = .007) and NC proliferation (19.7 ± 5.8%, p < .001), but these Snai2-enriched cells still apoptosed in response to alcohol. This was explained because alcohol induced p53 (198 ± 29%, p = .023), and the p53 antagonist pifithrin-α prevented their apoptosis. Moreover, alcohol counteracted Snai2's pro-survival signals, and Bcl2 was repressed (68.5 ± 6.0% of controls, p = .016) and PUMA was not induced, while ATM (1.32-fold, p = .01) and PTEN (1.30-fold, p = .028) were elevated.

CONCLUSIONS

Alcohol's calcium transient uncouples the Snai2/p53 regulatory loop that normally prevents apoptosis during EMT. This represents a novel pathway in alcohol's neurotoxicity, and complements demonstrations that alcohol suppresses PUMA in mouse NC. We propose that the NCs migratory behavior, and their requirement for Snai2/p53 co-expression, makes them vulnerable to stressors that dysregulate Snai2/p53 interactions, such as alcohol.

The Spatiotemporal Pattern and Intensity of p53 Activation Dictates Phenotypic Diversity in p53-Driven Developmental Syndromes

Inappropriate activation of the p53 transcription factor contributes to numerous developmental syndromes characterized by distinct constellations of phenotypes. How p53 drives exquisitely specific sets of symptoms in diverse syndromes, however, remains enigmatic. Here, we deconvolute the basis of p53-driven developmental syndromes by leveraging an array of mouse strains to modulate the spatial expression pattern, temporal profile, and magnitude of p53 activation during embryogenesis. We demonstrate that inappropriate p53 activation in the neural crest, facial ectoderm, anterior heart field, and endothelium induces distinct spectra of phenotypes. Moreover, altering the timing and degree of p53 hyperactivation substantially affects the phenotypic outcomes. Phenotypes are associated with p53-driven cell-cycle arrest or apoptosis, depending on the cell type, with gene expression programs, rather than extent of mitochondrial priming, largely governing the specific response. Together, our findings provide a critical framework for decoding the role of p53 as a mediator of diverse developmental syndromes.

High Oct4 expression: implications in the pathogenesis of neuroblastic tumours

BACKGROUND

Neuroblastic tumours (NBTs) are paediatric solid tumours derived from embryonic neural crest cells which harbour their own cancer stem cells (CSC). There is evidence indicating that CSC may be responsible for tumour progression, chemotherapy resistance and recurrence in NBTs. Oct4 is a transcription factor which plays a key role in mammal embryonic development and stem cell fate regulation. The aim of the study is to elucidate the clinical significance of Oct4 in NBTs.

METHODS

We studied Oct4 expression in 563 primary NBTs using digital image quantification. Chi-square test was applied to analyse the correlation between histopathology and the Oct4+ cell percentage. Survival analysis was carried out with Kaplan-Meier curves and log-rank test. Additionally, a multivariate Cox regression analysis with the stepwise backwards (Wald) method was undertaken to calculate the impact of Oct4 expression level on survival.

RESULTS

We found that tumours with a high proportion of cells expressing Oct4 correlated statistically with undifferentiated and poorly differentiated neuroblastoma / nodular ganglioneuroblastoma, and that Oct4 expression was not present in ganglioneuroma (p < 0.05). Statistical analysis also indicated a relationship between high Oct4 expression levels, high-risk patients according to the International Neuroblastoma Risk Group pre-treatment classification parameters, larger blood vessels and low survival rates.

CONCLUSIONS

These results suggest that the Oct4 gene may regulate NBT pathogenic differentiation pathways, and should thus be considered as a target for knockdown when developing novel therapies for high-risk NBT patients.

Overexpression of Fgfr2c causes craniofacial bone hypoplasia and ameliorates craniosynostosis in the Crouzon mouse

FGFR2c regulates many aspects of craniofacial and skeletal development. Mutations in the FGFR2 gene are causative of multiple forms of syndromic craniosynostosis, including Crouzon syndrome. Paradoxically, mouse studies have shown that the activation (Fgfr2cC342Y; a mouse model for human Crouzon syndrome), as well as the removal (Fgfr2cnull), of the FGFR2c isoform can drive suture abolishment. This study aims to address the downstream effects of pathogenic FGFR2c signalling by studying the effects of Fgfr2c overexpression. Conditional overexpression of Fgfr2c (R26RFgfr2c;βact) results in craniofacial hypoplasia as well as microtia and cleft palate. Contrary to Fgfr2cnull and Fgfr2cC342Y, Fgfr2c overexpression is insufficient to drive onset of craniosynostosis. Examination of the MAPK/ERK pathway in the embryonic sutures of Fgfr2cC342Y and R26RFgfr2c;βact mice reveals that both mutants have increased pERK expression. The contrasting phenotypes between Fgfr2cC342Y and R26RFgfr2c;βact mice prompted us to assess the impact of the Fgfr2c overexpression allele on the Crouzon mouse (Fgfr2cC342Y), in particular its effects on the coronal suture. Our results demonstrate that Fgfr2c overexpression is sufficient to partially rescue craniosynostosis through increased proliferation and reduced osteogenic activity in E18.5 Fgfr2cC342Y embryos. This study demonstrates the intricate balance of FGF signalling required for correct calvarial bone and suture morphogenesis, and that increasing the expression of the wild-type FGFR2c isoform could be a way to prevent or delay craniosynostosis progression.

Epigenetic and Transcriptomic Profiling of Mammary Gland Development and Tumor Models Disclose Regulators of Cell State Plasticity

Cell state reprogramming during tumor progression complicates accurate diagnosis, compromises therapeutic effectiveness, and fuels metastatic dissemination. We used chromatin accessibility assays and transcriptional profiling during mammary development as an agnostic approach to identify factors that mediate cancer cell state interconversions. We show that fetal and adult basal cells share epigenetic features consistent with multi-lineage differentiation potential. We find that DNA-binding motifs for SOX transcription factors are enriched in chromatin that is accessible in stem/progenitor cells and inaccessible in differentiated cells. In both mouse and human tumors, SOX10 expression correlates with stem/progenitor identity, dedifferentiation, and invasive characteristics. Strikingly, we demonstrate that SOX10 binds to genes that regulate neural crest cell identity, and that SOX10-positive tumor cells exhibit neural crest cell features.

Advillin Is Expressed in All Adult Neural Crest-Derived Neurons

Promoter-based genetic recombination (via, e.g., Cre-lox) is most useful when all cells of interest express a particular gene. The discovery that the actin-binding protein advillin is expressed in all somatic sensory neurons has been exploited repeatedly to drive DNA recombination therein, yet specificity of expression has not been well demonstrated. Here, we characterize advillin expression amongst sensory neurons and in several other neural and non-neural tissues. We first validate an advillin antibody against advillin knock-out tissue, advillin promoter-driven EGFP, and advillin mRNA expression. In the dorsal root ganglion (DRG), advillin is enriched in non-peptidergic nociceptors. We also show that advillin expression, and advillin promotor-driven EGFP and Cre-recombinase expression, occurs in multiple tissues including the dorsal habenula of the epithalamus, endocrine cells of the gut, Merkel cells in the skin, and most strikingly, throughout the autonomic nervous system (sympathetic, parasympathetic, and enteric neurons) in mice, rats, and non-human primates. In the mouse pelvic ganglion, advillin immunoreactivity is most intense in pairs of small neurons, and concentrated in spine-like structures on the axon initial segment contacted by sympathetic preganglionic axons. In autonomic targets (iris and blood vessels), advillin is distributed along cholinergic parasympathetic axons and in sympathetic varicosities. Developmentally, advillin expression is absent from sympathetics at postnatal day 4 but begins to emerge by day 7, accounting for previous reports (based on embryonic expression) of advillin's specificity to sensory neurons. These results indicate that caution is warranted in interpreting previous studies in which advillin-driven genomic editing is either constitutive or performed after postnatal day 4.

Cerebral Vein Malformations Result from Loss of Twist1 Expression and BMP Signaling from Skull Progenitor Cells and Dura

Dural cerebral veins (CV) are required for cerebrospinal fluid reabsorption and brain homeostasis, but mechanisms that regulate their growth and remodeling are unknown. We report molecular and cellular processes that regulate dural CV development in mammals and describe venous malformations in humans with craniosynostosis and TWIST1 mutations that are recapitulated in mouse models. Surprisingly, Twist1 is dispensable in endothelial cells but required for specification of osteoprogenitor cells that differentiate into preosteoblasts that produce bone morphogenetic proteins (BMPs). Inactivation of Bmp2 and Bmp4 in preosteoblasts and periosteal dura causes skull and CV malformations, similar to humans harboring TWIST1 mutations. Notably, arterial development appears normal, suggesting that morphogens from the skull and dura establish optimal venous networks independent from arterial influences. Collectively, our work establishes a paradigm whereby CV malformations result from primary or secondary loss of paracrine BMP signaling from preosteoblasts and dura, highlighting unique cellular interactions that influence tissue-specific angiogenesis in mammals.

Overexpression of DNMT3b target genes during Enteric Nervous System development contribute to the onset of Hirschsprung disease

Hirschsprung disease (HSCR) is attributed to a failure of neural crest cells (NCCs) to migrate, proliferate, differentiate and/or survive in the bowel wall during embryonic Enteric Nervous System (ENS) development. ENS formation is the result from a specific gene expression pattern regulated by epigenetic events, such DNA methylation by the DNA methyltransferases (DNMTs), among other mechanisms. Specifically, DNMT3b de novo methyltransferase is associated with NCCs development and has been shown to be implicated in ENS formation and in HSCR. Aiming to elucidate the specific mechanism underlying the DNMT3b role in such processes, we have performed a chromatin immunoprecipitation coupled with massively parallel sequencing analysis to identify the DNMT3B target genes in enteric precursor cells (EPCs) from mice. Moreover, the expression patterns of those target genes have been analyzed in human EPCs from HSCR patients in comparison with controls. Additionally, we have carried out a search of rare variants in those genes in a HSCR series. Through this approach we found 9 genes showing a significantly different expression level in both groups. Therefore, those genes may have a role in the proper human ENS formation and a failure in their expression pattern might contribute to this pathology.

Functional analysis of the zebrafish ortholog of HMGCS1 reveals independent functions for cholesterol and isoprenoids in craniofacial development

There are 8 different human syndromes caused by mutations in the cholesterol synthesis pathway. A subset of these disorders such as Smith-Lemli-Opitz disorder, are associated with facial dysmorphia. However, the molecular and cellular mechanisms underlying such facial deficits are not fully understood, primarily because of the diverse functions associated with the cholesterol synthesis pathway. Recent evidence has demonstrated that mutation of the zebrafish ortholog of HMGCR results in orofacial clefts. Here we sought to expand upon these data, by deciphering the cholesterol dependent functions of the cholesterol synthesis pathway from the cholesterol independent functions. Moreover, we utilized loss of function analysis and pharmacological inhibition to determine the extent of sonic hedgehog (Shh) signaling in animals with aberrant cholesterol and/or isoprenoid synthesis. Our analysis confirmed that mutation of hmgcs1, which encodes the first enzyme in the cholesterol synthesis pathway, results in craniofacial abnormalities via defects in cranial neural crest cell differentiation. Furthermore targeted pharmacological inhibition of the cholesterol synthesis pathway revealed a novel function for isoprenoid synthesis during vertebrate craniofacial development. Mutation of hmgcs1 had no effect on Shh signaling at 2 and 3 days post fertilization (dpf), but did result in a decrease in the expression of gli1, a known Shh target gene, at 4 dpf, after morphological deficits in craniofacial development and chondrocyte differentiation were observed in hmgcs1 mutants. These data raise the possibility that deficiencies in cholesterol modulate chondrocyte differentiation by a combination of Shh independent and Shh dependent mechanisms. Moreover, our results describe a novel function for isoprenoids in facial development and collectively suggest that cholesterol regulates craniofacial development through versatile mechanisms.

Intercellular crosstalk in human malignant melanoma

Incidence of malignant melanoma is increasing globally. While the initial stages of tumors can be easily treated by a simple surgery, the therapy of advanced stages is rather limited. Melanoma cells spread rapidly through the body of a patient to form multiple metastases. Consequently, the survival rate is poor. Therefore, emphasis in melanoma research is given on early diagnosis and development of novel and more potent therapeutic options. The malignant melanoma is arising from melanocytes, cells protecting mitotically active keratinocytes against damage caused by UV light irradiation. The melanocytes originate in the neural crest and consequently migrate to the epidermis. The relationship between the melanoma cells, the melanocytes, and neural crest stem cells manifests when the melanoma cells are implanted to an early embryo: they use similar migratory routes as the normal neural crest cells. Moreover, malignant potential of these melanoma cells is overdriven in this experimental model, probably due to microenvironmental reprogramming. This observation demonstrates the crucial role of the microenvironment in melanoma biology. Indeed, malignant tumors in general represent complex ecosystems, where multiple cell types influence the growth of genetically mutated cancer cells. This concept is directly applicable to the malignant melanoma. Our review article focuses on possible strategies to modify the intercellular crosstalk in melanoma that can be employed for therapeutic purposes.

Exploring the developmental mechanisms underlying Wolf-Hirschhorn Syndrome: Evidence for defects in neural crest cell migration

Wolf-Hirschhorn Syndrome (WHS) is a neurodevelopmental disorder characterized by mental retardation, craniofacial malformation, and defects in skeletal and heart development. The syndrome is associated with irregularities on the short arm of chromosome 4, including deletions of varying sizes and microduplications. Many of these genotypic aberrations in humans have been correlated with the classic WHS phenotype, and animal models have provided a context for mapping these genetic irregularities to specific phenotypes; however, there remains a significant knowledge gap concerning the cell biological mechanisms underlying these phenotypes. This review summarizes literature that has made recent contributions to this topic, drawing from the vast body of knowledge detailing the genetic particularities of the disorder and the more limited pool of information on its cell biology. Finally, we propose a novel characterization for WHS as a pathophysiology owing in part to defects in neural crest cell motility and migration during development.

Rescue of neural crest-derived phenotypes in a zebrafish CHARGE model by Sox10 downregulation

CHD7 mutations are implicated in a majority of cases of the congenital disorder, CHARGE syndrome. CHARGE, an autosomal dominant syndrome, is known to affect multiple tissues including eye, heart, ear, craniofacial nerves and skeleton and genital organs. Using a morpholino-antisense-oligonucleotide-based zebrafish model for CHARGE syndrome, we uncover a complex spectrum of abnormalities in the neural crest and the crest-derived cell types. We report for the first time, defects in myelinating Schwann cells, enteric neurons and pigment cells in a CHARGE model. We also observe defects in the specification of peripheral neurons and the craniofacial skeleton as previously reported. Chd7 morphants have impaired migration of neural crest cells and deregulation of sox10 expression from the early stages. Knocking down Sox10 in the zebrafish CHARGE model rescued the defects in Schwann cells and craniofacial cartilage. Our zebrafish CHARGE model thus reveals important regulatory roles for Chd7 at multiple points of neural crest development viz., migration, fate choice and differentiation and we suggest that sox10 deregulation is an important driver of the neural crest-derived aspects of Chd7 dependent CHARGE syndrome.

Imidacloprid Exposure Suppresses Neural Crest Cells Generation during Early Chick Embryo Development

Imidacloprid is a neonicotinoid pesticide that is widely used in the control pests found on crops and fleas on pets. However, it is still unclear whether imidacloprid exposure could affect early embryo development-despite some studies having been conducted on the gametes. In this study, we demonstrated that imidacloprid exposure could lead to abnormal craniofacial osteogenesis in the developing chick embryo. Cranial neural crest cells (NCCs) are the progenitor cells of the chick cranial skull. We found that the imidacloprid exposure retards the development of gastrulating chick embryos. HNK-1, PAX7, and Ap-2α immunohistological stainings indicated that cranial NCCs generation was inhibited after imidacloprid exposure. Double immunofluorescent staining (Ap-2α and PHIS3 or PAX7 and c-Caspase3) revealed that imidacloprid exposure inhibited both NCC proliferation and apoptosis. In addition, it inhibited NCCs production by repressing Msx1 and BMP4 expression in the developing neural tube and by altering expression of EMT-related adhesion molecules (Cad6B, E-Cadherin, and N-cadherin) in the developing neural crests. We also determined that imidacloprid exposure suppressed cranial NCCs migration and their ability to differentiate. In sum, we have provided experimental evidence that imidacloprid exposure during embryogenesis disrupts NCCs development, which in turn causes defective cranial bone development.

Accessory cells for β-cell transplantation

Despite recent advances, insulin therapy remains a treatment, not a cure, for diabetes mellitus with persistent risk of glycaemic alterations and life-threatening complications. Restoration of the endogenous β-cell mass through regeneration or transplantation offers an attractive alternative. Unfortunately, signals that drive β-cell regeneration remain enigmatic and β-cell replacement therapy still faces major hurdles that prevent its widespread application. Co-transplantation of accessory non-islet cells with islet cells has been shown to improve the outcome of experimental islet transplantation. This review will highlight current travails in β-cell therapy and focuses on the potential benefits of accessory cells for islet transplantation in diabetes.

The chick embryo as a model for the effects of prenatal exposure to alcohol on craniofacial development

Prenatal exposure to ethanol results in fetal alcohol spectrum disorder (FASD), a syndrome characterised by a broad range of clinical manifestations including craniofacial dysmorphologies and neurological defects. The characterisation of the mechanisms by which ethanol exerts its teratogenic effects is difficult due to the pleiotropic nature of its actions. Different experimental model systems have been employed to investigate the aetiology of FASD. Here, I will review studies using these different model organisms that have helped to elucidate how ethanol causes the craniofacial abnormalities characteristic of FASD. In these studies, ethanol was found to impair the prechordal plate-an important embryonic signalling centre-during gastrulation and to negatively affect the induction, migration and survival of the neural crest, a cell population that generates the cartilage and most of the bones of the skull. At the cellular level, ethanol appears to inhibit Sonic hedgehog signalling, alter levels of retionoic acid activity, trigger a Ca(2+)-CamKII-dependent pathway that antagonises WNT signalling, affect cytoskeletal dynamics and increase oxidative stress. Embryos of the domestic chick Gallus gallus domesticus have played a central role in developing a working model for the effects of ethanol on craniofacial development because they are easily accessible and because key steps in craniofacial development are particularly well established in the avian embryo. I will finish this review by highlighting some potential future avenues of fetal alcohol research.

A collagen VI-dependent pathogenic mechanism for Hirschsprung's disease

Hirschsprung's disease (HSCR) is a severe congenital anomaly of the enteric nervous system (ENS) characterized by functional intestinal obstruction due to a lack of intrinsic innervation in the distal bowel. Distal innervation deficiency results from incomplete colonization of the bowel by enteric neural crest cells (eNCCs), the ENS precursors. Here, we report the generation of a mouse model for HSCR--named Holstein--that contains an untargeted transgenic insertion upstream of the collagen-6α4 (Col6a4) gene. This insertion induces eNCC-specific upregulation of Col6a4 expression that increases total collagen VI protein levels in the extracellular matrix (ECM) surrounding both the developing and the postnatal ENS. Increased collagen VI levels during development mainly result in slower migration of eNCCs. This appears to be due to the fact that collagen VI is a poor substratum for supporting eNCC migration and can even interfere with the migration-promoting effects of fibronectin. Importantly, for a majority of patients in a HSCR cohort, the myenteric ganglia from the ganglionated region are also specifically surrounded by abundant collagen VI microfibrils, an outcome accentuated by Down syndrome. Collectively, our data thus unveil a clinically relevant pathogenic mechanism for HSCR that involves cell-autonomous changes in ECM composition surrounding eNCCs. Moreover, as COL6A1 and COL6A2 are on human Chr.21q, this mechanism is highly relevant to the predisposition of patients with Down syndrome to HSCR.

Using the avian mutant talpid2 as a disease model for understanding the oral-facial phenotypes of oral-facial-digital syndrome

Oral-facial-digital syndrome (OFD) is a ciliopathy that is characterized by oral-facial abnormalities, including cleft lip and/or palate, broad nasal root, dental anomalies, micrognathia and glossal defects. In addition, these individuals have several other characteristic abnormalities that are typical of a ciliopathy, including polysyndactyly, polycystic kidneys and hypoplasia of the cerebellum. Recently, a subset of OFD cases in humans has been linked to mutations in the centriolar protein C2 Ca(2+)-dependent domain-containing 3 (C2CD3). Our previous work identified mutations in C2CD3 as the causal genetic lesion for the avian talpid(2) mutant. Based on this common genetic etiology, we re-examined the talpid(2) mutant biochemically and phenotypically for characteristics of OFD. We found that, as in OFD-affected individuals, protein-protein interactions between C2CD3 and oral-facial-digital syndrome 1 protein (OFD1) are reduced in talpid(2) cells. Furthermore, we found that all common phenotypes were conserved between OFD-affected individuals and avian talpid(2) mutants. In light of these findings, we utilized the talpid(2) model to examine the cellular basis for the oral-facial phenotypes present in OFD. Specifically, we examined the development and differentiation of cranial neural crest cells (CNCCs) when C2CD3-dependent ciliogenesis was impaired. Our studies suggest that although disruptions of C2CD3-dependent ciliogenesis do not affect CNCC specification or proliferation, CNCC migration and differentiation are disrupted. Loss of C2CD3-dependent ciliogenesis affects the dispersion and directional persistence of migratory CNCCs. Furthermore, loss of C2CD3-dependent ciliogenesis results in dysmorphic and enlarged CNCC-derived facial cartilages. Thus, these findings suggest that aberrant CNCC migration and differentiation could contribute to the pathology of oral-facial defects in OFD.

A probabilistic assessment of the diagnosis of paraganglioma/pheochromocytoma based on clinical criteria and biochemical/imaging findings

Paragangliomas (PGL) and pheochromocytomas (P) are rare neural-crest-derived neoplasms. Very recently guidelines on diagnosis and treatment of PGL/P have been presented by the US Endocrine Society. In the following overview we assessed the implementation of these guidelines with probabilistic reasoning (calculating with Fagan nomograms the post-test probability of PGL/P for a given pre-test probability).

CONCLUSION

Biochemical evaluation of PGL/P showed excellent diagnostic characteristics with post-test probabilities that are very different from the pre-test probabilities, thus a positive biochemical test is usually indicative of disease whereas a negative one usually rules out disease. The post-test probabilities of anatomical and functional imaging modalities (i.e. in nuclear medicine) were different from the pre-test probabilities but to a lesser degree than the biochemical tests; furthermore in biochemically-proven PGL/P a negative imaging modality is not useful, while a positive one may indicate only one of multiple foci of metastatic/extra-adrenal disease. Thus, regarding imaging modalities, they should be combined in order to get the most of their characteristics for the localization of PGL/P.

Waardenburg syndrome type 2: an orthodontic perspective

Waardenburg syndrome is a rare form of neurocristopathy. It is a disorder in the development of neural crest cells, caused by an altered cellular migration during the embryonic phase. That alteration causes an association of different abnormalities such as pigmentary disturbances of the hair, iris, skin, stria vascularis of the cochlea, dystopia canthorum and sensorineural hearing loss. We report a case of a 14-year-old Romanian male, with a family history of Waardenburg syndrome (mother) and Usher syndrome (father - congenitally sensorineural hearing loss and retinal degeneration). The case particularities are: the correlation between malocclusion and Waardenburg syndrome due to hypoplastic alae nasi and also factors that produced hearing loss, which could be Waardenburg syndrome, Usher syndrome or the presence of the connexin 26 (W24X) gene mutation.

Neuroendocrine tumor arising de novo in the left upper thigh: a case report

Neuroendocrine tumors (NETs) originate in the neuroendocrine cells of the neural crest (Kulchitsky cells). If neuroendocrine tumors arising in the digestive tract or lung may occasionally result in skin metastases, primary soft tissue or skin NETs are infrequent. The current paper presents the case of an elderly woman patient with neuroendocrine tumors arising de novo in the left upper thigh, accompanied by lymph nodes metastases in the left groin and in the left pelvic sidewall, in close vicinity of the iliac vessels. The diagnosis of NET was performed based on immunohistochemical tests. Such tumors show a slow growth and, generally, have a good prognosis. It is emphasized that complete surgical excision, in some cases associated with adjuvant external radiotherapy is the optimal therapeutic modality in dealing with such lesions.

Leucophores are similar to xanthophores in their specification and differentiation processes in medaka

Animal body color is generated primarily by neural crest-derived pigment cells in the skin. Mammals and birds have only melanocytes on the surface of their bodies; however, fish have a variety of pigment cell types or chromatophores, including melanophores, xanthophores, and iridophores. The medaka has a unique chromatophore type called the leucophore. The genetic basis of chromatophore diversity remains poorly understood. Here, we report that three loci in medaka, namely, leucophore free (lf), lf-2, and white leucophore (wl), which affect leucophore and xanthophore differentiation, encode solute carrier family 2, member 15b (slc2a15b), paired box gene 7a (pax7a), and solute carrier family 2 facilitated glucose transporter, member 11b (slc2a11b), respectively. Because lf-2, a loss-of-function mutant for pax7a, causes defects in the formation of xanthophore and leucophore precursor cells, pax7a is critical for the development of the chromatophores. This genetic evidence implies that leucophores are similar to xanthophores, although it was previously thought that leucophores were related to iridophores, as these chromatophores have purine-dependent light reflection. Our identification of slc2a15b and slc2a11b as genes critical for the differentiation of leucophores and xanthophores in medaka led to a further finding that the existence of these two genes in the genome coincides with the presence of xanthophores in nonmammalian vertebrates: birds have yellow-pigmented irises with xanthophore-like intracellular organelles. Our findings provide clues for revealing diverse evolutionary mechanisms of pigment cell formation in animals.

Dilation of the inferior colliculus and hypersensitivity to sound in Wnt1-cre and Wnt1-GAL4 double-transgenic mice

The processing of sound information is mediated by the cochlea and the central auditory system. Among the central auditory system, the inferior colliculus (IC) has leading roles in the acoustic processing. In a previous study, we demonstrated psychiatric disorder-related behavioral abnormalities in a genetically modified animal of Wnt1-cre and Wnt1-GAL4 double-transgenic (dTg) mouse. Here we report an abnormal morphology of the IC and dysacusis in the dTg mice. The IC in the brain of the dTg mice is dilated in appearance and histologic analysis revealed a high cell-density in the IC. Also, the dTg mice showed high scores in a startle response test using a click box that emits a 20-kHz sound. Auditory brainstem response (ABR) test revealed lower ABR thresholds of the dTg mice at a test-stimulus frequency of 32kHz, but not at 4-16kHz. These findings suggest that the dTg mice could be a useful animal model for studying the physiologic function of the IC and the pathophysiology of psychiatric disorder-related dysacusis.

The prenatal origins of cancer

The concept that some childhood malignancies arise from postnatally persistent embryonal cells has a long history. Recent research has strengthened the links between driver mutations and embryonal and early postnatal development. This evidence, coupled with much greater detail on the cell of origin and the initial steps in embryonal cancer initiation, has identified important therapeutic targets and provided renewed interest in strategies for the early detection and prevention of childhood cancer.

Abnormal neural crest innervation in Sox10-Venus mice with all-trans retinoic acid-induced anorectal malformations

BACKGROUND/PURPOSE

Despite technical advances in the surgical/medical care of anorectal malformation (ARM), persistent unsatisfactory postoperative bowel habit has been attributed to histopathologic abnormalities of the distal rectum/pouch (DRP) and hypoplasia of anal sphincter muscles (ASM). We used Sox10-Venus mice with ARM induced by all-trans retinoic acid (ATRA) to investigate neural crest cell (NCC) innervation in the DRP and ASM.

METHOD

Pregnant Sox10-Venus mice were administered single doses of 50, 70, or 100 mg/kg of ATRA on embryonic day 8.5 (E8.5) then sacrificed on either E16.5 or E19.5. Bowel specimens comprising the anorectum were examined using fluorescence microscopy without immunohistochemical staining (FMIS). Anti-PGP9.5 was used to delineate ganglion cells and anti-SMA for smooth muscles.

RESULTS

The appropriate dose of ATRA for inducing ARM was 50 mg/kg. Under FMIS, all ARM embryos (n = 5; all high type; 3 male:2 female) had less NCC innervation with thick Venus-positive nerve fibers in the DRP compared with normal embryos (n = 8); there was abnormal NCC innervation in the DRP and absent ASM in ARM mice.

CONCLUSION

We are the first to delineate abnormal enteric nervous system innervation in the DRP of ARM mice without using immunohistochemical staining techniques thus allowing specimens to be examined without any distortion.

Beta-actin is required for proper mouse neural crest ontogeny

The mouse genome consists of six functional actin genes of which the expression patterns are temporally and spatially regulated during development and in the adult organism. Deletion of beta-actin in mouse is lethal during embryonic development, although there is compensatory expression of other actin isoforms. This suggests different isoform specific functions and, more in particular, an important function for beta-actin during early mammalian development. We here report a role for beta-actin during neural crest ontogeny. Although beta-actin null neural crest cells show expression of neural crest markers, less cells delaminate and their migration arrests shortly after. These phenotypes were associated with elevated apoptosis levels in neural crest cells, whereas proliferation levels were unchanged. Specifically the pre-migratory neural crest cells displayed higher levels of apoptosis, suggesting increased apoptosis in the neural tube accounts for the decreased amount of migrating neural crest cells seen in the beta-actin null embryos. These cells additionally displayed a lack of membrane bound N-cadherin and dramatic decrease in cadherin-11 expression which was more pronounced in the pre-migratory neural crest population, potentially indicating linkage between the cadherin-11 expression and apoptosis. By inhibiting ROCK ex vivo, the knockout neural crest cells regained migratory capacity and cadherin-11 expression was upregulated. We conclude that the presence of beta-actin is vital for survival, specifically of pre-migratory neural crest cells, their proper emigration from the neural tube and their subsequent migration. Furthermore, the absence of beta-actin affects cadherin-11 and N-cadherin function, which could partly be alleviated by ROCK inhibition, situating the Rho-ROCK signaling in a feedback loop with cadherin-11.

A pre-clinical murine model of oral implant osseointegration

Many of our assumptions concerning oral implant osseointegration are extrapolated from experimental models studying skeletal tissue repair in long bones. This disconnect between clinical practice and experimental research hampers our understanding of bone formation around oral implants and how this process can be improved. We postulated that oral implant osseointegration would be fundamentally equivalent to implant osseointegration elsewhere in the body. Mice underwent implant placement in the edentulous ridge anterior to the first molar and peri-implant tissues were evaluated at various timepoints after surgery. Our hypothesis was disproven; oral implant osseointegration is substantially different from osseointegration in long bones. For example, in the maxilla peri-implant pre-osteoblasts are derived from cranial neural crest whereas in the tibia peri-implant osteoblasts are derived from mesoderm. In the maxilla, new osteoid arises from periostea of the maxillary bone but in the tibia the new osteoid arises from the marrow space. Cellular and molecular analyses indicate that osteoblast activity and mineralization proceeds from the surfaces of the native bone and osteoclastic activity is responsible for extensive remodeling of the new peri-implant bone. In addition to histologic features of implant osseointegration, molecular and cellular assays conducted in a murine model provide new insights into the sequelae of implant placement and the process by which bone is generated around implants.