RESUMO
Secreted Wnt morphogens are signaling molecules essential for embryogenesis, pathogenesis, and regeneration and require distinct modifications for secretion, gradient formation, and activity. Whether Wnt proteins can be posttranslationally inactivated during development and homeostasis is unknown. Here we identify, through functional cDNA screening, a transmembrane protein Tiki1 that is expressed specifically in the dorsal Spemann-Mangold Organizer and is required for anterior development during Xenopus embryogenesis. Tiki1 antagonizes Wnt function in embryos and human cells via a TIKI homology domain that is conserved from bacteria to mammals and acts likely as a protease to cleave eight amino-terminal residues of a Wnt protein, resulting in oxidized Wnt oligomers that exhibit normal secretion but minimized receptor-binding capability. Our findings identify a Wnt-specific protease that controls head formation, reveal a mechanism for morphogen inactivation through proteolysis-induced oxidation-oligomerization, and suggest a role of the Wnt amino terminus in evasion of oxidizing inactivation. TIKI proteins may represent potential therapeutic targets.
Assuntos
Padronização Corporal , Cabeça/embriologia , Proteínas de Membrana/metabolismo , Metaloproteases/metabolismo , Via de Sinalização Wnt , Proteínas de Xenopus/metabolismo , Xenopus/embriologia , Sequência de Aminoácidos , Animais , Embrião não Mamífero/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Células HEK293 , Células HeLa , Humanos , Proteínas de Membrana/genética , Metaloproteases/genética , Dados de Sequência Molecular , Organizadores Embrionários/metabolismo , Alinhamento de Sequência , Xenopus/metabolismo , Proteínas de Xenopus/genéticaRESUMO
This paper introduces a single-cell atlas for pivotal developmental stages in Xenopus, encompassing gastrulation, neurulation, and early tailbud. Notably surpassing its predecessors, the new atlas enhances gene mapping, read counts, and gene/cell type nomenclature. Leveraging the latest Xenopus tropicalis genome version, alongside advanced alignment pipelines and machine learning for cell type assignment, this release maintains consistency with previous cell type annotations while rectifying nomenclature issues. Employing an unbiased approach for cell type assignment proves especially apt for embryonic contexts, given the considerable number of non-terminally differentiated cell types. An alternative cell type attribution here adopts a fuzzy, non-deterministic stance, capturing the transient nature of early embryo progenitor cells by presenting an ensemble of types in superposition. The value of the new resource is emphasized through numerous examples, with a focus on previously unexplored germ cell populations where we uncover novel transcription onset features. Offering interactive exploration via a user-friendly web portal and facilitating complete data downloads, this atlas serves as a comprehensive and accessible reference.
Assuntos
Xenopus , Animais , Xenopus/embriologia , Xenopus/genética , Gastrulação , Embrião não Mamífero/citologia , Neurulação/genética , Neurulação/fisiologia , Análise de Célula Única/métodos , Regulação da Expressão Gênica no DesenvolvimentoRESUMO
During vertebrate gastrulation, mesoderm is induced in pluripotent cells, concomitant with dorsal-ventral patterning and establishing of the dorsal axis. We applied single-cell chromatin accessibility and transcriptome analyses to explore the emergence of cellular heterogeneity during gastrulation in Xenopus tropicalis. Transcriptionally inactive lineage-restricted genes exhibit relatively open chromatin in animal caps, whereas chromatin accessibility in dorsal marginal zone cells more closely reflects transcriptional activity. We characterized single-cell trajectories and identified head and trunk organizer cell clusters in early gastrulae. By integrating chromatin accessibility and transcriptome data, we inferred the activity of transcription factors in single-cell clusters and tested the activity of organizer-expressed transcription factors in animal caps, alone or in combination. The expression profile induced by a combination of Foxb1 and Eomes most closely resembles that observed in the head organizer. Genes induced by Eomes, Otx2, or the Irx3-Otx2 combination are enriched for maternally regulated H3K4me3 modifications, whereas Lhx8-induced genes are marked more frequently by zygotically controlled H3K4me3. Taken together, our results show that transcription factors cooperate in a combinatorial fashion in generally open chromatin to orchestrate zygotic gene expression.
Assuntos
Cromatina/genética , Análise de Célula Única/métodos , Fatores de Transcrição/metabolismo , Proteínas de Xenopus/genética , Xenopus/embriologia , Animais , Padronização Corporal , Cromatina/metabolismo , Gastrulação , Perfilação da Expressão Gênica , Regulação da Expressão Gênica no Desenvolvimento , Análise de Sequência de RNA , Xenopus/genética , Proteínas de Xenopus/metabolismoRESUMO
The size of the nucleus varies among different cell types, species, and disease states, but mechanisms of nuclear size regulation are poorly understood. We investigated nuclear scaling in the pseudotetraploid frog Xenopus laevis and its smaller diploid relative Xenopus tropicalis, which contains smaller cells and nuclei. Nuclear scaling was recapitulated in vitro using egg extracts, demonstrating that titratable cytoplasmic factors determine nuclear size to a greater extent than DNA content. Nuclear import rates correlated with nuclear size, and varying the concentrations of two transport factors, importin α and Ntf2, was sufficient to account for nuclear scaling between the two species. Both factors modulated lamin B3 import, with importin α increasing overall import rates and Ntf2 reducing import based on cargo size. Importin α also contributes to nuclear size changes during early X. laevis development. Thus, nuclear transport mechanisms are physiological regulators of both interspecies and developmental nuclear scaling.
Assuntos
Núcleo Celular , Proteínas de Transporte Nucleocitoplasmático/metabolismo , Proteínas de Xenopus/metabolismo , Xenopus laevis/metabolismo , Xenopus/metabolismo , alfa Carioferinas/metabolismo , Transporte Ativo do Núcleo Celular , Animais , Lamina Tipo B/metabolismo , Xenopus/embriologia , Xenopus laevis/embriologiaRESUMO
Understanding the mechanisms of embryonic cell cycles is a central goal of developmental biology, as the regulation of the cell cycle must be closely coordinated with other events during early embryogenesis. Quantitative imaging approaches have recently begun to reveal how the cell cycle oscillator is controlled in space and time, and how it is integrated with mechanical signals to drive morphogenesis. Here, we discuss how the Drosophila embryo has served as an excellent model for addressing the molecular and physical mechanisms of embryonic cell cycles, with comparisons to other model systems to highlight conserved and species-specific mechanisms. We describe how the rapid cleavage divisions characteristic of most metazoan embryos require chemical waves and cytoplasmic flows to coordinate morphogenesis across the large expanse of the embryo. We also outline how, in the late cleavage divisions, the cell cycle is inter-regulated with the activation of gene expression to ensure a reliable maternal-to-zygotic transition. Finally, we discuss how precise transcriptional regulation of the timing of mitosis ensures that tissue morphogenesis and cell proliferation are tightly controlled during gastrulation.
Assuntos
Pontos de Checagem do Ciclo Celular/fisiologia , Drosophila/embriologia , Desenvolvimento Embrionário/fisiologia , Animais , Proteína Quinase CDC2 , Ciclo Celular/genética , Proteínas de Drosophila , Embrião de Mamíferos , Embrião não Mamífero/metabolismo , Desenvolvimento Embrionário/genética , Regulação da Expressão Gênica no Desenvolvimento , Mitose , Morfogênese , Xenopus/embriologia , Zigoto/metabolismoRESUMO
Mutations in the RNA helicase DDX3 have emerged as a frequent cause of intellectual disability in humans. Because many individuals carrying DDX3 mutations have additional defects in craniofacial structures and other tissues containing neural crest (NC)-derived cells, we hypothesized that DDX3 is also important for NC development. Using Xenopus tropicalis as a model, we show that DDX3 is required for normal NC induction and craniofacial morphogenesis by regulating AKT kinase activity. Depletion of DDX3 decreases AKT activity and AKT-dependent inhibitory phosphorylation of GSK3ß, leading to reduced levels of ß-catenin and Snai1: two GSK3ß substrates that are crucial for NC induction. DDX3 function in regulating these downstream signaling events during NC induction is likely mediated by RAC1, a small GTPase whose translation depends on the RNA helicase activity of DDX3. These results suggest an evolutionarily conserved role of DDX3 in NC development by promoting AKT activity, and provide a potential mechanism for the NC-related birth defects displayed by individuals harboring mutations in DDX3 and its downstream effectors in this signaling cascade.
Assuntos
RNA Helicases DEAD-box/metabolismo , Crista Neural/embriologia , Crista Neural/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Proteínas de Xenopus/metabolismo , Xenopus/embriologia , Xenopus/metabolismo , Animais , Cartilagem/embriologia , Cartilagem/metabolismo , Embrião não Mamífero/metabolismo , Face/embriologia , Regulação da Expressão Gênica no Desenvolvimento , Glicogênio Sintase Quinase 3 beta/metabolismo , Morfogênese/genética , Fosforilação , Estabilidade Proteica , Crânio/embriologia , Crânio/metabolismo , Fatores de Transcrição da Família Snail/metabolismo , Via de Sinalização Wnt , Xenopus/genética , beta Catenina/metabolismo , Proteínas rac1 de Ligação ao GTP/metabolismoRESUMO
DYRK1A [dual specificity tyrosine-(Y)-phosphorylation-regulated kinase 1 A] is a high-confidence autism risk gene that encodes a conserved kinase. In addition to autism, individuals with putative loss-of-function variants in DYRK1A exhibit microcephaly, intellectual disability, developmental delay and/or congenital anomalies of the kidney and urinary tract. DYRK1A is also located within the critical region for Down syndrome; therefore, understanding the role of DYRK1A in brain development is crucial for understanding the pathobiology of multiple developmental disorders. To characterize the function of this gene, we used the diploid frog Xenopus tropicalis We discover that Dyrk1a is expressed in ciliated tissues, localizes to ciliary axonemes and basal bodies, and is required for ciliogenesis. We also demonstrate that Dyrk1a localizes to mitotic spindles and that its inhibition leads to decreased forebrain size, abnormal cell cycle progression and cell death during brain development. These findings provide hypotheses about potential mechanisms of pathobiology and underscore the utility of X. tropicalis as a model system for understanding neurodevelopmental disorders.
Assuntos
Encéfalo/anatomia & histologia , Cílios/metabolismo , Embrião não Mamífero/anatomia & histologia , Transtornos do Neurodesenvolvimento/genética , Organogênese/genética , Proteínas Serina-Treonina Quinases/genética , Proteínas Tirosina Quinases/genética , Proteínas de Xenopus/genética , Xenopus/embriologia , Xenopus/genética , Animais , Encéfalo/embriologia , Ciclo Celular/genética , Sobrevivência Celular , Regulação da Expressão Gênica no Desenvolvimento , Predisposição Genética para Doença , Tamanho do Órgão , Fenótipo , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas Tirosina Quinases/metabolismo , Fatores de Risco , Fuso Acromático/metabolismo , Telencéfalo/anatomia & histologia , Proteínas de Xenopus/metabolismoRESUMO
Among its multiple functions, p53 is a critical regulator of TGF-beta responses. Sasai et al. (2008) now identify a new p53 inhibitory protein, XFDL156. During embryonic development, this factor is expressed in the ectoderm germ layer and maintains the pluripotency of ectodermal cells by inhibiting TGF-beta target genes that promote mesoderm specification.
Assuntos
Diferenciação Celular , Fator de Crescimento Transformador beta/metabolismo , Proteína Supressora de Tumor p53/metabolismo , Xenopus/embriologia , Animais , Ectoderma/citologia , Ectoderma/metabolismo , Mesoderma/citologia , Mesoderma/metabolismo , Xenopus/metabolismoRESUMO
In this issue, Inomata et al. (2008) report that the scaffold protein Olfactomedin 1 (ONT1) recruits the Tolloid proteases to their substrate Chordin, an antagonist of bone morphogenetic proteins (BMPs), during development of the frog embryo. Consequently, ONT1 expression in the organizer of the late gastrula stabilizes the gradient of BMP signaling that is essential for dorsoventral patterning.
Assuntos
Proteínas da Matriz Extracelular/metabolismo , Glicoproteínas/metabolismo , Peptídeos e Proteínas de Sinalização Intercelular/metabolismo , Proteínas de Xenopus/metabolismo , Xenopus/embriologia , Animais , Padronização Corporal , Proteínas Morfogenéticas Ósseas/metabolismo , Embrião não Mamífero/metabolismoRESUMO
Two new studies reveal the role of microtubule polarity in the asymmetric localization of mRNAs. In this issue of Cell, Zimyanin et al. (2008) show that the asymmetric localization of oskar mRNA in fruit fly oocytes results from a slight bias in the direction of its transport. Meanwhile, Messitt et al. (2008) reporting in Developmental Cell find a subpopulation of microtubules that is critical for the asymmetric distribution of Vg1 mRNA in frog oocytes.
Assuntos
Microtúbulos/metabolismo , Oócitos/metabolismo , Transporte de RNA , RNA Mensageiro/metabolismo , Animais , Drosophila/embriologia , Proteínas de Drosophila/genética , Humanos , Oócitos/química , RNA Mensageiro/análise , Fator de Crescimento Transformador beta/genética , Xenopus/embriologia , Proteínas de Xenopus/genéticaRESUMO
Idiopathic hypocalcemia in Thoroughbred (TB) foals causes tetany and seizures and is invariably fatal. Based upon the similarity of this disease with human familial hypoparathyroidism and occurrence only in the TB breed, we conducted a genetic investigation on two affected TB foals. Familial hypoparathyroidism was identified, and pedigree analysis suggested an autosomal recessive (AR) mode of inheritance. We performed whole-genome sequencing of the two foals, their unaffected dams and four unaffected, unrelated TB horses. Both homozygosity mapping and an association analysis were used to prioritize potential genetic variants. Of the 2,808 variants that significantly associated with the phenotype using an AR mode of inheritance (P<0.02) and located within a region of homozygosity, 1,507 (54%) were located in a 9.7 Mb region on chr4 (44.9-54.6 Mb). Within this region, a nonsense variant (RAPGEF5 c.2624C>A,p.Ser875*) was significantly associated with the hypoparathyroid phenotype (Pallelic = 0.008). Affected foals were homozygous for the variant, with two additional affected foals subsequently confirmed in 2019. Necropsies of all affected foals failed to identify any histologically normal parathyroid glands. Because the nonsense mutation in RAPGEF5 was near the C-terminal end of the protein, the impact on protein function was unclear. Therefore, we tested the variant in our Xenopus overexpression model and demonstrated RAPGEF5 loss-of-function. This RAPGEF5 variant represents the first genetic variant for hypoparathyroidism identified in any domestic animal species.
Assuntos
Códon sem Sentido , Doenças dos Cavalos/genética , Hipocalcemia/veterinária , Hipoparatireoidismo/veterinária , Fatores ras de Troca de Nucleotídeo Guanina/genética , Fatores ras de Troca de Nucleotídeo Guanina/metabolismo , Animais , Embrião não Mamífero , Feminino , Homozigoto , Doenças dos Cavalos/etiologia , Cavalos , Hipocalcemia/genética , Hipocalcemia/patologia , Hipoparatireoidismo/genética , Hipoparatireoidismo/patologia , Masculino , Linhagem , Sequenciamento Completo do Genoma , Xenopus/embriologia , Fatores ras de Troca de Nucleotídeo Guanina/químicaRESUMO
Ciliopathies affect a variety of tissues during development including the heart, kidneys, respiratory tract, and retina. Though an increasing number of monogenic causes of ciliopathies have been described, many remain unexplained. Recently, recessive variants in NUP93 and NUP205 encoding two proteins of the inner ring of the nuclear pore complex were implicated as causes of steroid resistant nephrotic syndrome. In addition, we previously found that the inner ring nucleoporins NUP93 and NUP188 function in proper left-right patterning in developing embryos via a role at the cilium. Here, we describe the role of an additional inner ring nucleoporin NUP205 in cilia biology and establishment of normal organ situs. Using knockdown in Xenopus, we show that Nup205 depletion results in loss of cilia and abnormal cardiac morphology. Furthermore, by transmission electron microscopy, we observe a loss of cilia and mispositioning of intracellular ciliary structures such as basal bodies and rootlets upon depleting inner ring nucleoporins. We describe a model wherein NUP93 interacting with either NUP188 or NUP205 is necessary for cilia. We thus provide evidence that dysregulation of inner ring nucleoporin genes that have been identified in patients may contribute to pathogenesis through cilia dysfunction.
Assuntos
Cílios/fisiologia , Complexo de Proteínas Formadoras de Poros Nucleares/fisiologia , Proteínas de Xenopus/fisiologia , Animais , Padronização Corporal , Cílios/ultraestrutura , Epiderme/embriologia , Epiderme/ultraestrutura , Técnicas de Silenciamento de Genes , Cardiopatias Congênitas/genética , Humanos , Complexo de Proteínas Formadoras de Poros Nucleares/genética , Pronefro/ultraestrutura , Xenopus/embriologia , Proteínas de Xenopus/genéticaRESUMO
Xenopus tadpoles are a unique model for regeneration in that they exhibit two distinct phases of age-specific regenerative competence. In Xenopus laevis, young tadpoles fully regenerate following major injuries such as tail transection, then transiently lose regenerative competence during the "refractory period" from stages 45-47. Regenerative competence is then regained in older tadpoles before being permanently lost during metamorphosis. Here we show that a similar refractory period exists in X. tropicalis. Notably, tadpoles lose regenerative competence gradually in X. tropicalis, with full regenerative competence lost at stage 47. We find that the refractory period coincides closely with depletion of maternal yolk stores and the onset of independent feeding, and so we hypothesized that it might be caused in part by nutrient stress. In support of this hypothesis, we find that cell proliferation declines throughout the tail as the refractory period approaches. When we block nutrient mobilization by inhibiting mTOR signaling, we find that tadpole growth and regeneration are reduced, while yolk stores persist. Finally, we are able to restore regenerative competence and cell proliferation during the refractory period by abundantly feeding tadpoles. Our study argues that nutrient stress contributes to lack of regenerative competence and introduces the X. tropicalis refractory period as a valuable new model for interrogating how metabolic constraints inform regeneration.
Assuntos
Regeneração/fisiologia , Cauda/fisiologia , Xenopus/embriologia , Animais , Proliferação de Células , Gema de Ovo , Larva/metabolismo , Metamorfose Biológica/fisiologia , Nutrientes , Transdução de Sinais , Xenopus/metabolismo , Proteínas de Xenopus/metabolismoRESUMO
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.
Assuntos
Anormalidades Múltiplas/enzimologia , Face/anormalidades , Doenças Hematológicas/enzimologia , Histona-Lisina N-Metiltransferase/genética , Histona-Lisina N-Metiltransferase/metabolismo , Crista Neural/metabolismo , Doenças Vestibulares/enzimologia , Proteínas de Xenopus/genética , Proteínas de Xenopus/metabolismo , Anormalidades Múltiplas/genética , Anormalidades Múltiplas/metabolismo , Anormalidades Múltiplas/patologia , Acetilação , Animais , Movimento Celular/genética , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Face/patologia , Doenças Hematológicas/genética , Doenças Hematológicas/metabolismo , Doenças Hematológicas/patologia , Histonas/metabolismo , Mutação com Perda de Função , Metilação , Mutação , Proteínas de Neoplasias/genética , Proteínas de Neoplasias/metabolismo , Crista Neural/enzimologia , Crista Neural/patologia , Placa Neural/crescimento & desenvolvimento , Placa Neural/metabolismo , Placa Neural/patologia , Semaforinas/genética , Semaforinas/metabolismo , Doenças Vestibulares/genética , Doenças Vestibulares/metabolismo , Doenças Vestibulares/patologia , Xenopus/embriologia , Xenopus/genética , Xenopus/metabolismo , Proteínas de Xenopus/fisiologiaRESUMO
Primary ciliary dyskinesia (PCD) is a genetic disorder in which impaired ciliary function leads to chronic airway disease. Exome sequencing of a PCD subject identified an apparent homozygous frameshift variant, c.887_890delTAAG (p.Val296Glyfs∗13), in exon 5; this frameshift introduces a stop codon in amino acid 308 of the growth arrest-specific protein 2-like 2 (GAS2L2). Further genetic screening of unrelated PCD subjects identified a second proband with a compound heterozygous variant carrying the identical frameshift variant and a large deletion (c.867_∗343+1207del; p.?) starting in exon 5. Both individuals had clinical features of PCD but normal ciliary axoneme structure. In this research, using human nasal cells, mouse models, and X.laevis embryos, we show that GAS2L2 is abundant at the apical surface of ciliated cells, where it localizes with basal bodies, basal feet, rootlets, and actin filaments. Cultured GAS2L2-deficient nasal epithelial cells from one of the affected individuals showed defects in ciliary orientation and had an asynchronous and hyperkinetic (GAS2L2-deficient = 19.8 Hz versus control = 15.8 Hz) ciliary-beat pattern. These results were recapitulated in Gas2l2-/- mouse tracheal epithelial cell (mTEC) cultures and in X. laevis embryos treated with Gas2l2 morpholinos. In mice, the absence of Gas2l2 caused neonatal death, and the conditional deletion of Gas2l2 impaired mucociliary clearance (MCC) and led to mucus accumulation. These results show that a pathogenic variant in GAS2L2 causes a genetic defect in ciliary orientation and impairs MCC and results in PCD.
Assuntos
Cílios/patologia , Transtornos da Motilidade Ciliar/genética , Transtornos da Motilidade Ciliar/fisiopatologia , Proteínas dos Microfilamentos/deficiência , Proteínas Associadas aos Microtúbulos/deficiência , Proteínas de Xenopus/deficiência , Animais , Transtornos da Motilidade Ciliar/patologia , Modelos Animais de Doenças , Éxons/genética , Feminino , Deleção de Genes , Genes Letais , Humanos , Masculino , Camundongos , Camundongos Knockout , Proteínas dos Microfilamentos/genética , Proteínas Associadas aos Microtúbulos/genética , Fenótipo , Rotação , Xenopus/embriologia , Xenopus/genética , Proteínas de Xenopus/genéticaRESUMO
SOX4, together with SOX11 and SOX12, forms group C of SRY-related (SOX) transcription factors. They play key roles, often in redundancy, in multiple developmental pathways, including neurogenesis and skeletogenesis. De novo SOX11 heterozygous mutations have been shown to cause intellectual disability, growth deficiency, and dysmorphic features compatible with mild Coffin-Siris syndrome. Using trio-based exome sequencing, we here identify de novo SOX4 heterozygous missense variants in four children who share developmental delay, intellectual disability, and mild facial and digital morphological abnormalities. SOX4 is highly expressed in areas of active neurogenesis in human fetuses, and sox4 knockdown in Xenopus embryos diminishes brain and whole-body size. The SOX4 variants cluster in the highly conserved, SOX family-specific HMG domain, but each alters a different residue. In silico tools predict that each variant affects a distinct structural feature of this DNA-binding domain, and functional assays demonstrate that these SOX4 proteins carrying these variants are unable to bind DNA in vitro and transactivate SOX reporter genes in cultured cells. These variants are not found in the gnomAD database of individuals with presumably normal development, but 12 other SOX4 HMG-domain missense variants are recorded and all demonstrate partial to full activity in the reporter assay. Taken together, these findings point to specific SOX4 HMG-domain missense variants as the cause of a characteristic human neurodevelopmental disorder associated with mild facial and digital dysmorphism.
Assuntos
Anormalidades Múltiplas/genética , Mutação de Sentido Incorreto/genética , Transtornos do Neurodesenvolvimento/genética , Fatores de Transcrição SOXC/genética , Sequência de Aminoácidos , Animais , Criança , Pré-Escolar , Síndrome de Coffin-Lowry/genética , Estudos de Coortes , Sequência Conservada , DNA/genética , DNA/metabolismo , Feminino , Domínios HMG-Box/genética , Heterozigoto , Humanos , Masculino , Fatores de Transcrição SOX/química , Fatores de Transcrição SOX/genética , Fatores de Transcrição SOXC/química , Fatores de Transcrição SOXC/metabolismo , Ativação Transcricional , Xenopus/anatomia & histologia , Xenopus/embriologia , Xenopus/genética , Proteínas de Xenopus/química , Proteínas de Xenopus/genéticaAssuntos
Fenômenos Biomecânicos , Biologia do Desenvolvimento , Vida , Morfogênese/fisiologia , Adulto , Animais , Membrana Basal , Encéfalo/anatomia & histologia , Encéfalo/citologia , Encéfalo/embriologia , Drosophila melanogaster/citologia , Drosophila melanogaster/embriologia , Embrião de Mamíferos/citologia , Embrião de Mamíferos/embriologia , Embrião de Mamíferos/metabolismo , Fertilização in vitro , Coração/anatomia & histologia , Coração/embriologia , Humanos , Camundongos , Morfogênese/genética , Miosina Tipo II/metabolismo , Organogênese/genética , Pressão , Neoplasias Cutâneas/irrigação sanguínea , Neoplasias Cutâneas/genética , Neoplasias Cutâneas/patologia , Neoplasias Cutâneas/fisiopatologia , Xenopus/anatomia & histologia , Xenopus/embriologia , Peixe-Zebra/anatomia & histologia , Peixe-Zebra/embriologia , Peixe-Zebra/crescimento & desenvolvimentoRESUMO
Xenopus oocytes can epigenetically reprogram mouse somatic cells toward totipotency. In this issue, Jullien et al. (2014) now describe rapid, interdependent molecular events that facilitate this reprogramming.
Assuntos
Reprogramação Celular/genética , Cromatina/metabolismo , Histonas/fisiologia , Oócitos/metabolismo , Xenopus/embriologia , AnimaisRESUMO
Nuclear transfer to oocytes is an efficient way to transcriptionally reprogram somatic nuclei, but its mechanisms remain unclear. Here, we identify a sequence of molecular events that leads to rapid transcriptional reprogramming of somatic nuclei after transplantation to Xenopus oocytes. RNA-seq analyses reveal that reprogramming by oocytes results in a selective switch in transcription toward an oocyte rather than pluripotent type, without requiring new protein synthesis. Time-course analyses at the single-nucleus level show that transcriptional reprogramming is induced in most transplanted nuclei in a highly hierarchical manner. We demonstrate that an extensive exchange of somatic- for oocyte-specific factors mediates reprogramming and leads to robust oocyte RNA polymerase II binding and phosphorylation on transplanted chromatin. Moreover, genome-wide binding of oocyte-specific linker histone B4 supports its role in transcriptional reprogramming. Thus, our study reveals the rapid, abundant, and stepwise loading of oocyte-specific factors onto somatic chromatin as important determinants for successful reprogramming.
Assuntos
Reprogramação Celular/genética , Cromatina/metabolismo , Histonas/fisiologia , Oócitos/metabolismo , Xenopus/embriologia , Animais , Células Cultivadas , Reprogramação Celular/fisiologia , Genoma , Camundongos , Técnicas de Transferência Nuclear , Especificidade de Órgãos , RNA/genética , Análise de Sequência de RNA , Xenopus/genéticaRESUMO
DNA methylation is a major epigenetic modification; however, the precise role of DNA methylation in vertebrate development is still not fully understood. Here, we show that DNA methylation is essential for the establishment of the left-right (LR) asymmetric body plan during vertebrate embryogenesis. Perturbation of DNA methylation by depletion of DNA methyltransferase 1 (dnmt1) or dnmt3bb.1 in zebrafish embryos leads to defects in dorsal forerunner cell (DFC) specification or collective migration, laterality organ malformation, and disruption of LR patterning. Knockdown of dnmt1 in Xenopus embryos also causes similar defects. Mechanistically, loss of dnmt1 function induces hypomethylation of the lefty2 gene enhancer and promotes lefty2 expression, which consequently represses Nodal signaling in zebrafish embryos. We also show that Dnmt3bb.1 regulates collective DFC migration through cadherin 1 (Cdh1). Taken together, our data uncover dynamic DNA methylation as an epigenetic mechanism to control LR determination during early embryogenesis in vertebrates.