endothelin-1 and Craniofacial-Abnormalities

The shaping of the vertebrate head results from highly dynamic integrated processes involving the growth and exchange of signals between the ectoderm, the endoderm, the mesoderm and Cephalic Neural Crest Cells (CNCCs). During embryonic development, these tissues change their shape and relative position rapidly and come transiently in contact with each other. Molecular signals exchanged in restricted regions of tissue interaction are crucial in providing positional identity to the mesenchymes which will form the different skeletal and muscular components of the head. Slight spatio-temporal modifications of these signalling maps can result in profound changes in craniofacial development and might have contributed to the evolution of facial diversity. Abnormal signalling patterns could also be at the origin of congenital craniofacial malformations. This review brings into perspective recent work on spatial and temporal aspects of facial morphogenesis with particular focus on the molecular mechanisms of jaw specification.

Topics: Animals; Body Patterning; Craniofacial Abnormalities; Ectoderm; Endoderm; Endothelin-1; Gene Expression Regulation, Developmental; Humans; Jaw; Mesoderm; Models, Biological; Neural Crest; Signal Transduction; Time Factors; Tretinoin

Topics: Animals; Branchial Region; Cardiovascular Abnormalities; Cardiovascular System; Craniofacial Abnormalities; Endothelin-1; Hirschsprung Disease; Humans; Mice; Mice, Knockout; Neural Crest; Phenotype; Receptor, Endothelin A; Signal Transduction

Forward genetic analyses can reveal important developmental regulatory genes and how they function to pattern morphology. This is because a mutated gene can produce a novel, sometimes beautiful, phenotype that, like the normal phenotype, immediately seems worth understanding. Generally the loss-of-function mutant phenotype is simplified from the wild-type one, and often the nature of the pattern simplification allows one to deduce how the wild-type gene contributes to patterning the normal, more complex, morphology. This truism seems no less valid for the vertebrate head skeleton than for other and simpler cases of patterning in multicellular plants and animals. To show this, we review selected zebrafish craniofacial mutants. "Midline group" mutations, in genes functioning in one of at least three signal transduction pathways, lead to neurocranial pattern truncations that are primarily along the mediolateral axis. Mutation of lazarus/pbx4, encoding a hox gene partner, and mutation of valentino/kreisler, a hox gene regulator, produce anterior-posterior axis disruptions of pharyngeal cartilages. Dorsoventral axis patterning of the same cartilages is disrupted in sucker/endothelin-1 mutants. We infer that different signal transduction pathways pattern cartilage development along these three separate axes. Patterning of at least the anterior-posterior and dorsoventral axes have been broadly conserved, e.g., reduced Endothelin-1 signaling similarly perturbs cartilage specification in chick, mouse, and zebrafish. We hypothesize that Endothelin-1 also is an upstream organizer of the patterns of cellular interactions during cartilage morphogenesis.

Topics: Animals; Body Patterning; Bone Development; Cartilage; Craniofacial Abnormalities; Endothelin-1; Genes, Homeobox; Head; Larva; Morphogenesis; Mutation; Signal Transduction; Zebrafish

A series of gene targeting research have revealed novel roles of endothelins (ETs), peptides with potent vasoconstrictive and proliferative activities, in neural crest development in mammals. The phenotype of mice lacking the ET-1/ET-A receptor-mediated signalling affects cranial/cardiac neural crest-derived structures including the branchial arches and great vessels, and is highly similar to a set of the phenotypes of the avian neural crest ablation model. In contrast, mice lacking the ET-3/ET-B receptor-mediated signalling have defects in enteric neurons and melanocytes derived from trunk/vagal neural crest, resulting in megacolon and coat color spotting. Thus, both distinct pathways of the ET system seem to participate in the normal development of different neural crest lineages. Moreover, mutations in the human ET-3 and ET-B receptor genes have been identified in patients with Hirschsprung disease. As for the mechanisms involving the ET system in neural crest development, HANDs and Goosecoid, transcriptional factors essential for embryogenesis, have been suggested as key molecules downstream to the ET-mediated signalling in cranial/cardiac neural crest.

Topics: Animals; Cardiovascular Diseases; Craniofacial Abnormalities; Endothelin-1; Endothelin-3; Endothelins; Gene Expression Regulation, Developmental; Hirschsprung Disease; Humans; Mice; Mice, Knockout; Neural Crest; Receptor, Endothelin A; Receptor, Endothelin B; Receptors, Endothelin

Inborn errors of cholesterol metabolism occur as a result of mutations in the cholesterol synthesis pathway (CSP). Although mutations in the CSP cause a multiple congenital anomaly syndrome, craniofacial abnormalities are a hallmark phenotype associated with these disorders. Previous studies have established that mutation of the zebrafish hmgcs1 gene (Vu57 allele), which encodes the first enzyme in the CSP, causes defects in craniofacial development and abnormal neural crest cell (NCC) differentiation. However, the molecular mechanisms by which the products of the CSP disrupt NCC differentiation are not completely known. Cholesterol is known to regulate the activity of WNT signaling, an established regulator of NCC differentiation. We hypothesized that defects in cholesterol synthesis are associated with reduced WNT signaling, consequently resulting in abnormal craniofacial development. To test our hypothesis we performed a combination of pharmaceutical inhibition, gene expression assays, and targeted rescue experiments to understand the function of the CSP and WNT signaling during craniofacial development. We demonstrate reduced expression of four canonical WNT downstream target genes in homozygous carriers of the Vu57 allele and reduced axin2 expression, a known WNT target gene, in larvae treated with Ro-48-8071, an inhibitor of cholesterol synthesis. Moreover, activation of WNT signaling via treatment with WNT agonist I completely restored the craniofacial defects present in a subset of animals carrying the Vu57 allele. Collectively, these data suggest interplay between the CSP and WNT signaling during craniofacial development.

Topics: Alleles; Animals; Axin Protein; Cell Differentiation; Cholesterol; Collagen Type II; Craniofacial Abnormalities; Cyclin D1; Down-Regulation; Embryo, Nonmammalian; Endothelin-1; Face; Female; Gene Expression Regulation, Developmental; Genotype; Male; Mutation; Neural Crest; Phenotype; SOXE Transcription Factors; Transcription Factors; Wnt Signaling Pathway; Zebrafish; Zebrafish Proteins

Jaw morphogenesis is a complex event mediated by inductive signals that establish and maintain the distinct developmental domains required for formation of hinged jaws, the defining feature of gnathostomes. The mandibular portion of pharyngeal arch 1 is patterned dorsally by Jagged-Notch signaling and ventrally by endothelin receptor A (EDNRA) signaling. Loss of EDNRA signaling disrupts normal ventral gene expression, the result of which is homeotic transformation of the mandible into a maxilla-like structure. However, loss of Jagged-Notch signaling does not result in significant changes in maxillary development. Here we show in mouse that the transcription factor SIX1 regulates dorsal arch development not only by inducing dorsal

Topics: Animals; Body Patterning; Branchial Region; Craniofacial Abnormalities; Embryo, Mammalian; Endothelin-1; Gene Expression Regulation, Developmental; Homeodomain Proteins; Integrases; Maxilla; Mice; Models, Biological; Neural Crest; Receptor, Endothelin A; Receptors, Notch; Serrate-Jagged Proteins; Signal Transduction; Sp7 Transcription Factor; Transcription Factors; Up-Regulation; Zygoma

Interferon Regulatory Factor 6 (IRF6) and TWIST1 are transcription factors necessary for craniofacial development. Human genetic studies showed that mutations in IRF6 lead to cleft lip and palate and mandibular abnormalities. In the mouse, we found that loss of Irf6 causes craniosynostosis and mandibular hypoplasia. Similarly, mutations in TWIST1 cause craniosynostosis, mandibular hypoplasia and cleft palate. Based on this phenotypic overlap, we asked if Irf6 and Twist1 interact genetically during craniofacial formation. While single heterozygous mice are normal, double heterozygous embryos (Irf6

Topics: Alleles; Animals; Apoptosis; Cell Death; Cell Line; Cell Proliferation; Craniofacial Abnormalities; Endothelin-1; Enhancer Elements, Genetic; Epistasis, Genetic; Facial Bones; Female; Fluorescent Antibody Technique; Gene Dosage; Gene Expression Regulation, Developmental; Genotype; Humans; Interferon Regulatory Factors; Male; Mandible; Mice; Mice, Knockout; Mutation; Nuclear Proteins; Organ Specificity; Organogenesis; Phenotype; Protein Binding; Skull; Twist-Related Protein 1

The purpose of the present study was to identify the potential effect of prenatal vitamin B12 administration on retinoic acid (RA)-induced early craniofacial abnormalities in mice and to investigate the possible mechanisms by which vitamin B12 reduces malformations.. In our study, whole embryo culture was used to explore the effect of vitamin B12 on mouse embryos during the critical period of organogenesis. All embryos were exposed to 0.4 µM RA and different concentrations of vitamin B12 and scored for their growth in the branchial region at the end of a 48-hour culture period. The endothelin-1 (ET-1)/dHAND protein expression levels in the first branchial arch were investigated using an immunohistochemical method.. In the whole embryo culture, 100 and 10 µM vitamin B12 dose-dependently prevented branchial region malformations and decreased craniofacial defects by 90.5% and 77.3%, respectively. ET-1 and dHAND protein levels were significantly increased in vitamin B12-supplemented embryos compared to the RA-exposed group in embryonic branchial region.. These results suggest that vitamin B12 may prevent RA-induced craniofacial abnormalities via prevention of an RA-induced decrease of ET-1 and dHAND protein levels in the branchial region during the organogenic period. This study may shed new light on preventing craniofacial abnormalities.

Topics: Animals; Basic Helix-Loop-Helix Transcription Factors; Branchial Region; Craniofacial Abnormalities; Dose-Response Relationship, Drug; Embryo Culture Techniques; Embryonic Development; Endothelin-1; Facial Bones; Female; Male; Mice; Mice, Inbred ICR; Microcephaly; Neural Tube Defects; Tretinoin; Vitamin B 12; Vitamin B Complex

The endothelin (Edn) system comprises three ligands (Edn1, Edn2 and Edn3) and their G-protein-coupled type A (Ednra) and type B (Ednrb) receptors. During embryogenesis, the Edn1/Ednra signaling is thought to regulate the dorsoventral axis patterning of pharyngeal arches via Dlx5/Dlx6 upregulation. To further clarify the underlying mechanism, we have established mice in which gene cassettes can be efficiently knocked-in into the Ednra locus using recombinase-mediated cassette exchange (RMCE) based on the Cre-lox system. The first homologous recombination introducing mutant lox-flanked Neo resulted in homeotic transformation of the lower jaw to an upper jaw, as expected. Subsequent RMCE-mediated knock-in of lacZ targeted its expression to the cranial/cardiac neural crest derivatives as well as in mesoderm-derived head mesenchyme. Knock-in of Ednra cDNA resulted in a complete rescue of craniofacial defects of Ednra-null mutants. By contrast, Ednrb cDNA could not rescue them except for the most distal pharyngeal structures. At early stages, the expression of Dlx5, Dlx6 and their downstream genes was downregulated and apoptotic cells distributed distally in the mandible of Ednrb-knock-in embryos. These results, together with similarity in craniofacial defects between Ednrb-knock-in mice and neural-crest-specific Galpha(q)/Galpha(11)-deficient mice, indicate that the dorsoventral axis patterning of pharyngeal arches is regulated by the Ednra-selective, G(q)/G(11)-dependent signaling, while the formation of the distal pharyngeal region is under the control of a G(q)/G(11)-independent signaling, which can be substituted by Ednrb. This RMCE-mediated knock-in system can serve as a useful tool for studies on gene functions in craniofacial development.

Topics: Animals; beta-Galactosidase; Branchial Region; Craniofacial Abnormalities; DNA, Complementary; Embryo, Mammalian; Embryonic Development; Endothelin-1; Gene Expression Regulation, Developmental; GTP-Binding Protein alpha Subunits, Gq-G11; Mesoderm; Mice; Mice, Inbred C57BL; Models, Biological; Muscle, Skeletal; Mutagenesis, Insertional; Neural Crest; Phenotype; Receptor, Endothelin A; Receptor, Endothelin B; Recombinases; Signal Transduction

Intake of retinoic acid (RA) or of its precursor, vitamin A, during early pregnancy is associated with increased incidence of craniofacial lesions. The origin of these teratogenic effects remains enigmatic as in cranial neural crest cells (CNCCs), which largely contribute to craniofacial structures, the RA-transduction pathway is not active. Recent results suggest that RA could act on the endoderm of the first pharyngeal arch (1stPA), through a RARbeta-dependent mechanism.. Here we show that RA provokes dramatically different craniofacial malformations when administered at slightly different developmental times within a narrow temporal interval corresponding to the colonization of the 1(st) PA by CNCCs. We provide evidence showing that RA acts on the signalling epithelium of the 1(st) PA, gradually reducing the expression of endothelin-1 and Fgf8. These two molecular signals are instrumental in activating Dlx genes in incoming CNCCs, thereby triggering the morphogenetic programs, which specify different jaw elements.. The anatomical series induced by RA-treatments at different developmental times parallels, at least in some instances, the supposed origin of modern jaws (e.g., the fate of the incus). Our results might provide a conceptual framework for the rise of jaw morphotypes characteristic of gnathostomes.

Topics: Animals; Craniofacial Abnormalities; Early Growth Response Protein 2; Embryo, Mammalian; Endothelin-1; Female; Gene Expression Regulation, Developmental; Homeodomain Proteins; In Situ Hybridization; Jaw; Keratolytic Agents; Mice; Mice, Transgenic; Molecular Dynamics Simulation; Neural Crest; Pregnancy; Receptors, Retinoic Acid; Signal Transduction; Tretinoin

Craniofacial birth defects result from defects in cranial neural crest (NC) patterning and morphogenesis. The vertebrate craniofacial skeleton is derived from cranial NC cells and the patterning of these cells occurs within the pharyngeal arches. Substantial efforts have led to the identification of several genes required for craniofacial skeletal development such as the endothelin-1 (edn1) signaling pathway that is required for lower jaw formation. However, many essential genes required for craniofacial development remain to be identified.. Through screening a collection of insertional zebrafish mutants containing approximately 25% of the genes essential for embryonic development, we present the identification of 15 essential genes that are required for craniofacial development. We identified 3 genes required for hyomandibular development. We also identified zebrafish models for Campomelic Dysplasia and Ehlers-Danlos syndrome. To further demonstrate the utility of this method, we include a characterization of the wdr68 gene. We show that wdr68 acts upstream of the edn1 pathway and is also required for formation of the upper jaw equivalent, the palatoquadrate. We also present evidence that the level of wdr68 activity required for edn1 pathway function differs between the 1st and 2nd arches. Wdr68 interacts with two minibrain-related kinases, Dyrk1a and Dyrk1b, required for embryonic growth and myotube differentiation, respectively. We show that a GFP-Wdr68 fusion protein localizes to the nucleus with Dyrk1a in contrast to an engineered loss of function mutation Wdr68-T284F that no longer accumulated in the cell nucleus and failed to rescue wdr68 mutant animals. Wdr68 homologs appear to exist in all eukaryotic genomes. Notably, we found that the Drosophila wdr68 homolog CG14614 could substitute for the vertebrate wdr68 gene even though insects lack the NC cell lineage.. This work represents a systematic identification of approximately 25% of the essential genes required for craniofacial development. The identification of zebrafish models for two human disease syndromes indicates that homologs to the other genes are likely to also be relevant for human craniofacial development. The initial characterization of wdr68 suggests an important role in craniofacial development for the highly conserved Wdr68-Dyrk1 protein complexes.

Topics: Animals; Body Patterning; Conserved Sequence; Craniofacial Abnormalities; Endothelin-1; Gene Expression; Mutation; Neural Crest; Nuclear Proteins; Zebrafish; Zebrafish Proteins

Prevention of retinoic acid-induced craniofacial abnormalities by folinic acid, and endothelin-1 (ET-1)/dHAND protein and mRNA expression were investigated in mouse embryos using the whole embryo culture, streptavidin-biotin peroxidase complex method, and whole-mount in situ hybridization. In the whole embryo culture, 1.0 and 0.1 mm-folinic acid dose dependently prevented branchial region malformations and decreased defects by 93 % and 77 %, respectively. Folinic acid at concentrations of 1.0 and 0.1 mm significantly increased ET-1 and dHAND protein expression levels compared to retinoic acid-exposed values in embryonic branchial areas. Folinic acid also increased ET-1 and dHAND mRNA levels in the same region. The present results suggest that folinic acid may prevent retinoic acid-induced craniofacial abnormalities via increasing ET-1 and dHAND levels in the branchial region during the organogenic period.

Topics: Animals; Basic Helix-Loop-Helix Transcription Factors; Brain; Branchial Region; Craniofacial Abnormalities; Embryo Culture Techniques; Embryo, Mammalian; Endothelin-1; Female; Gene Expression Regulation; Immunohistochemistry; In Situ Hybridization; Leucovorin; Male; Mice; RNA, Messenger; Teratogens; Tretinoin; Vitamin B Complex

Neural crest cells arise in the dorsal aspect of the neural tube and migrate extensively to differentiate into a variety of neural and non-neural tissues. While interactions between neural crest cells and their local environments are required for the proper development of these tissues, little information is available about the molecular nature of the cell-cell interactions in cephalic neural crest development. Here we demonstrate that mice deficient for one type of endothelin receptor, ETA, mimic the human conditions collectively termed CATCH 22 or velocardiofacial syndrome, which include severe craniofacial deformities and defects in the cardiovascular outflow tract. We show that ETA receptor mRNA is expressed by the neural crest-derived ectomesenchymal cells of pharyngeal arches and cardiac outflow tissues, whereas ET-1 ligand mRNA is expressed by arch epithelium, paraxial mesoderm-derived arch core and the arch vessel endothelium. This suggests that paracrine interaction between neural crest-derived cells and both ectoderm and mesoderm is essential in forming the skeleton and connective tissue of the head. Further, we find that pharyngeal arch expression of goosecoid is absent in ETA receptor-deficient mice, placing the transcription factor as one of the possible downstream signals triggered by activation of the ETA receptor. These observations define a novel genetic pathway for inductive communication between cephalic neural crest cells and their environmental counterparts.

Topics: Animals; Animals, Newborn; Base Sequence; Brain; Branchial Region; Craniofacial Abnormalities; DNA Primers; DNA-Binding Proteins; Endothelin-1; Female; Gene Expression Regulation, Developmental; Goosecoid Protein; Heart Defects, Congenital; Homeodomain Proteins; Humans; In Situ Hybridization; Mice; Mice, Knockout; Neural Crest; Polymerase Chain Reaction; Pregnancy; Receptor, Endothelin A; Receptors, Endothelin; Repressor Proteins; RNA, Messenger; Signal Transduction; Transcription Factors