RESUMEN
Mesendoderm cells are key intermediate progenitors that form at the early primitive streak (PrS) and give rise to mesoderm and endoderm in the gastrulating embryo. We have identified an interaction between CNOT3 and the cell cycle kinase Aurora B that requires sequences in the NOT box domain of CNOT3 and regulates MAPK/ERK signaling during mesendoderm differentiation. Aurora B phosphorylates CNOT3 at two sites located close to a nuclear localization signal and promotes localization of CNOT3 to the nuclei of mouse embryonic stem cells (ESCs) and metastatic lung cancer cells. ESCs that have both sites mutated give rise to embryoid bodies that are largely devoid of mesoderm and endoderm and are composed mainly of cells with ectodermal characteristics. The mutant ESCs are also compromised in their ability to differentiate into mesendoderm in response to FGF2, BMP4, and Wnt3 due to reduced survival and proliferation of differentiating mesendoderm cells. We also show that the double mutation alters the balance of interaction of CNOT3 with Aurora B and with ERK and reduces phosphorylation of ERK in response to FGF2. Our results identify a potential adaptor function for CNOT3 that regulates the Ras/MEK/ERK pathway during embryogenesis.
Asunto(s)
Aurora Quinasa B/metabolismo , Quinasas MAP Reguladas por Señal Extracelular/metabolismo , Células Madre Embrionarias de Ratones/citología , Factores de Transcripción/metabolismo , Células A549 , Animales , Aurora Quinasa B/genética , Diferenciación Celular/fisiología , Supervivencia Celular , Células Cultivadas , Endodermo/citología , Endodermo/fisiología , Quinasas MAP Reguladas por Señal Extracelular/genética , Femenino , Humanos , Mesodermo/citología , Ratones , Células Madre Embrionarias de Ratones/fisiología , Mutación , Fosforilación , Factores de Transcripción/genéticaRESUMEN
It is generally accepted that epiblast cells ingress into the primitive streak by epithelial-to-mesenchymal transition (EMT) to give rise to the mesoderm; however, it is less clear how the endoderm acquires an epithelial fate. Here, we used embryonic stem cell and mouse embryo knock-in reporter systems to combine time-resolved lineage labelling with high-resolution single-cell transcriptomics. This allowed us to resolve the morphogenetic programs that segregate the mesoderm from the endoderm germ layer. Strikingly, while the mesoderm is formed by classical EMT, the endoderm is formed independent of the key EMT transcription factor Snail1 by mechanisms of epithelial cell plasticity. Importantly, forkhead box transcription factor A2 (Foxa2) acts as an epithelial gatekeeper and EMT suppressor to shield the endoderm from undergoing a mesenchymal transition. Altogether, these results not only establish the morphogenetic details of germ layer formation, but also have broader implications for stem cell differentiation and cancer metastasis.
Asunto(s)
Blastocisto/fisiología , Plasticidad de la Célula , Endodermo/fisiología , Células Epiteliales/fisiología , Transición Epitelial-Mesenquimal , Gastrulación , Células Madre Embrionarias de Ratones/fisiología , Animales , Blastocisto/citología , Blastocisto/metabolismo , Diferenciación Celular , Línea Celular , Endodermo/citología , Endodermo/metabolismo , Células Epiteliales/metabolismo , Regulación del Desarrollo de la Expresión Génica , Edad Gestacional , Factor Nuclear 3-beta del Hepatocito/genética , Factor Nuclear 3-beta del Hepatocito/metabolismo , Ratones , Ratones Transgénicos , Células Madre Embrionarias de Ratones/metabolismo , Fenotipo , Factores de Transcripción de la Familia Snail/genética , Factores de Transcripción de la Familia Snail/metabolismo , Factores de TiempoRESUMEN
We identified a human embryonic stem cell subline that fails to respond to the differentiation cues needed to obtain endoderm derivatives, differentiating instead into extra-embryonic mesoderm. RNA-sequencing analysis showed that the subline has hyperactivation of the WNT and BMP4 signalling. Modulation of these pathways with small molecules confirmed them as the cause of the differentiation impairment. While activation of WNT and BMP4 in control cells resulted in a loss of endoderm differentiation and induction of extra-embryonic mesoderm markers, inhibition of these pathways in the subline restored its ability to differentiate. Karyotyping and exome sequencing analysis did not identify any changes in the genome that could account for the pathway deregulation. These findings add to the increasing evidence that different responses of stem cell lines to differentiation protocols are based on genetic and epigenetic factors, inherent to the line or acquired during cell culture.
Asunto(s)
Proteína Morfogenética Ósea 4/genética , Diferenciación Celular/genética , Células Madre Embrionarias Humanas/fisiología , Proteínas Wnt/genética , Proteína Morfogenética Ósea 4/metabolismo , Células Cultivadas , Endodermo/citología , Endodermo/fisiología , Membranas Extraembrionarias/citología , Membranas Extraembrionarias/metabolismo , Perfilación de la Expresión Génica , Regulación del Desarrollo de la Expresión Génica , Células Madre Embrionarias Humanas/metabolismo , Humanos , Mesodermo/citología , Mesodermo/fisiología , Transducción de Señal/genética , Transcriptoma , Proteínas Wnt/metabolismoRESUMEN
During Xenopus gastrulation, leading edge mesendoderm (LEM) advances animally as a wedge-shaped cell mass over the vegetally moving blastocoel roof (BCR). We show that close contact across the BCR-LEM interface correlates with attenuated net advance of the LEM, which is pulled forward by tip cells while the remaining LEM frequently separates from the BCR. Nevertheless, lamellipodia persist on the detached LEM surface. They attach to adjacent LEM cells and depend on PDGF-A, cell-surface fibronectin and cadherin. We argue that active cell motility on the LEM surface prevents adverse capillary effects in the liquid LEM tissue as it moves by being pulled. It counters tissue surface-tension effects with oriented cell movement and bulges the LEM surface out to keep it close to the curved BCR without attaching to it. Proximity to the BCR is necessary, in turn, for the maintenance and orientation of lamellipodia that permit mass cell movement with minimal substratum contact. Together with a similar process in epithelial invagination, vertical telescoping, the cell movement at the LEM surface defines a novel type of cell rearrangement: vertical shearing.
Asunto(s)
Movimiento Celular/fisiología , Gastrulación/fisiología , Mesodermo/fisiología , Xenopus laevis/fisiología , Animales , Cadherinas/metabolismo , Acción Capilar , Adhesión Celular/fisiología , Endodermo/metabolismo , Endodermo/fisiología , Fibronectinas/metabolismo , Gástrula/metabolismo , Gástrula/fisiología , Mesodermo/metabolismo , Seudópodos/metabolismo , Seudópodos/fisiología , Xenopus laevis/metabolismoRESUMEN
Roots vary their permeability to aid radial transport of solutes towards xylem vessels in response to nutritional cues. Nitrogen (N) depletion was previously shown to induce early suberization of endodermal cell walls and reduce hydraulic conductivity of barley roots suggesting reduced apoplastic transport of ions (Armand et al., 2019). Suberization may also limit transcellular ion movement by blocking access to transporters (Barberon et al., 2016). The aim of this study was to confirm that N depletion induced suberization in the roots of barley and demonstrate that this was a specific effect in response to NO3- depletion. Furthermore, in roots with early and enhanced suberization, we assessed their ability for transporter-mediated NO3- influx. N depletion induced lateral root elongation and early and enhanced endodermal suberization of the seminal root of each genotype. Both root to shoot NO3- translocation and net N uptake was half that of plants supplied with steady-state NO3-. Genes with predicted functions in suberin synthesis (HvHORST) and NO3- transport (HvNRT2.2) were induced under N-deplete conditions. N-deplete roots had a higher capacity for high-affinity NO3- influx in early suberized roots than under optimal NO3-. In conclusion, NO3- depletion induced early and enhanced suberization in the roots of barley, however, suberization did not restrict transcellular NO3- transport.
Asunto(s)
Endodermo/fisiología , Hordeum/metabolismo , Lípidos/fisiología , Nitratos/metabolismo , Nitrógeno/metabolismo , Transporte Biológico , Raíces de Plantas/metabolismoRESUMEN
Biophysical cues synergize with biochemical cues to drive differentiation of pluripotent stem cells through specific phenotypic trajectory. Tools to manipulate the cell biophysical environment and identify the influence of specific environment perturbation in the presence of combinatorial inputs will be critical to control the development trajectory. Here we describe the procedure to perturb biophysical environment of pluripotent stem cells while maintaining them in 3D culture configuration. We also discuss a high-throughput platform for combinatorial perturbation of the cell microenvironment, and detail a statistical procedure to extract dominant environmental influences.
Asunto(s)
Diferenciación Celular , Linaje de la Célula , Endodermo/fisiología , Técnica del Anticuerpo Fluorescente , Mecanotransducción Celular , Microscopía Fluorescente , Células Madre Pluripotentes/fisiología , Nicho de Células Madre , Ingeniería de Tejidos , Alginatos/química , Técnicas de Cultivo de Célula , Células Cultivadas , Endodermo/citología , Regulación del Desarrollo de la Expresión Génica , Humanos , Modelos Estadísticos , Fenotipo , Factores de TiempoRESUMEN
We previously identified the protein Lbh as necessary for cranial neural crest (CNC) cell migration in Xenopus through the use of morpholinos. However, Lbh is a maternally deposited protein and morpholinos achieve knockdowns through prevention of translation. In order to investigate the role of Lbh in earlier embryonic events, we employed the new technique "Trim-Away" to degrade this maternally deposited protein. Trim-Away utilizes the E3 ubiquitin ligase trim21 to degrade proteins targeted with an antibody and was developed in mammalian systems. Our results show that Xenopus is amenable to the Trim-Away technique. We also show that early knockdown of Lbh in Xenopus results in defects in gastrulation that present with a decrease in fibronectin matrix assembly, an increased in mesodermal cell migration and decrease in endodermal cell cohesion. We further show that the technique is also effective on a second abundant maternal protein PACSIN2. We discuss potential advantages and limit of the technique in Xenopus embryos as well as the mechanism of gastrulation inhibition.
Asunto(s)
Gastrulación , Proteínas de Xenopus/fisiología , Xenopus laevis/embriología , Proteínas Adaptadoras Transductoras de Señales/inmunología , Proteínas Adaptadoras Transductoras de Señales/metabolismo , Animales , Anticuerpos Monoclonales/inmunología , Movimiento Celular , Ectodermo/citología , Ectodermo/embriología , Ectodermo/patología , Inducción Embrionaria , Endodermo/citología , Endodermo/embriología , Endodermo/fisiología , Fibronectinas/metabolismo , Mesodermo/citología , Mesodermo/embriología , Mesodermo/fisiología , Morfolinos , Cresta Neural/citología , Cresta Neural/embriología , Proteolisis , Ribonucleoproteínas/genética , Ribonucleoproteínas/metabolismo , Proteínas de Xenopus/genética , Proteínas de Xenopus/inmunología , Proteínas de Xenopus/metabolismoRESUMEN
TBX1 is a major disease gene of 22q11.2 deletion syndrome (22q11.2DS). It is expressed in all three germ layers of pharyngeal apparatus to control the complicated morphogenesis. The haploinsufficiency of pharyngeal endodermal or ectodermal, but not mesodermal Tbx1 causes aortic arch patterning defect. However, the mesodermal deletion of Tbx1 causes much severer pharyngeal and cardiovascular defect than either pharyngeal endodermal or ectodermal Tbx1 deletion does. It is inconsistent with the conventional thought that the invagination of pharyngeal epithelia drives pharyngeal segmentation. Therefore, we asked whether pharyngeal ectodermal and ectodermal Tbx1 can compensate the loss of each other. Here we carefully characterized pharyngeal epithelia-specific Fgf15Cre and Fgf15HspCre lines and used them to perform pharyngeal epithelia-specific deletion. Our data showed that the percentage of E18.5 Fgf15Cre;Tbx1flox/+ embryos with aortic arch patterning defects was similar to that of E10.5 Fgf15Cre;Tbx1flox/+ embryos with the 4th pharyngeal arch artery (PAA) defect, indicating that there is no significant recovery from the initial PAA defect, in contrast to germ line haploinsufficiency. Fgf15Cre;Tbx1flox/flox embryos had hypoplastic caudal pharyngeal arch and defective derivatives, but cardiac OFT development was not affected. The phenotypic spectrum of simultaneous Tbx1 deletion in both pharyngeal ectoderm and endoderm is strikingly similar to what presents with single pharyngeal endoderm or ectoderm-specific deletion of Tbx1. The absence of synergistic effect indicates intimate topographic interactions among pharyngeal endoderm and ectoderm, through which deletion of a gene in one tissue may disrupt the development of adjacent tissues and thereby lead to similar morphological phenotypes in either tissue-specific deletion.
Asunto(s)
Región Branquial/anomalías , Cardiopatías Congénitas/genética , Proteínas de Dominio T Box/genética , Animales , Ectodermo/fisiología , Endodermo/fisiología , Epitelio/fisiología , Eliminación de Gen , Regulación del Desarrollo de la Expresión Génica , Haploinsuficiencia/genética , Integrasas/genética , Ratones Endogámicos C57BL , Ratones Mutantes , Ratones Transgénicos , Proteínas de Dominio T Box/metabolismoRESUMEN
In several model animals, the earliest phases of embryogenesis are regulated by lineage-specific genes, such as Drosophila bicoid Sea urchin (echinoid) embryogenesis is initiated by zygotic expression of pmar1, a paired-class homeobox gene that has been considered to be present only in the lineage of modern urchins (euechinoids). In euechinoids, Pmar1 promotes endomesoderm specification by repressing the hairy and enhancer of split C (hesC) gene. Here, we have identified the basal echinoid (cidaroid) pmar1 gene, which also promotes endomesoderm specification but not by repressing hesC A further search for related genes demonstrated that other echinoderms have pmar1-related genes named phb Functional analyses of starfish Phb proteins indicated that, similar to cidaroid Pmar1, they promote activation of endomesoderm regulatory gene orthologs via an unknown repressor that is not HesC. Based on these results, we propose that Pmar1 may have recapitulated the regulatory function of Phb during the early diversification of echinoids and that the additional repressor HesC was placed under the control of Pmar1 in the euechinoid lineage. This case provides an exceptional model for understanding how early developmental processes diverge.
Asunto(s)
Endodermo/fisiología , Proteínas de Homeodominio/fisiología , Mesodermo/fisiología , Erizos de Mar/embriología , Animales , Diferenciación Celular , Linaje de la Célula , Desarrollo Embrionario , Perfilación de la Expresión Génica , Regulación del Desarrollo de la Expresión Génica , Redes Reguladoras de Genes , Larva/fisiología , Fenotipo , Filogenia , Receptores Notch/fisiología , Erizos de Mar/genéticaRESUMEN
The Mexican salamander, Ambystoma mexicanum (Axolotl), is an excellent vertebrate model system to understand development and regeneration. Studies in axolotl embryos have provided important insights into taste bud development. Taste bud specification and determination occur in the oropharyngeal endoderm of axolotl embryos during gastrulation and neurulation, respectively, whereas taste bud innervation and taste cell differentiation occur later in development. Axolotl embryos are amenable to microsurgery, and tissue explants develop readily in vitro. We performed RNA-seq analysis to investigate the differential expression of genes in oropharyngeal explants at several stages of taste cell differentiation. Since the axolotl genome has only recently been sequenced, we used a Trinity pipeline to perform de novo assembly of sequencing reads. Linear models for RNA-seq data were used to identify differentially expressed genes. We found 1234 unique genes differentially expressed during taste cell differentiation stages. We validated four of these genes using RTqPCR and performed GO functional analysis. The differential expression of these genes suggests that they may play a role in taste cell differentiation in axolotls.
Asunto(s)
Ambystoma mexicanum/genética , Ambystoma mexicanum/fisiología , Diferenciación Celular/fisiología , Orofaringe/fisiología , Papilas Gustativas/fisiología , Transcriptoma/genética , Animales , Endodermo/fisiología , Perfilación de la Expresión Génica/métodos , Regeneración/genética , Regeneración/fisiologíaRESUMEN
Tunicates are a diverse group of invertebrate marine chordates that includes the larvaceans, thaliaceans, and ascidians. Because of their unique evolutionary position as the sister group of the vertebrates, tunicates are invaluable as a comparative model and hold the promise of revealing both conserved and derived features of chordate gastrulation. Descriptive studies in a broad range of tunicates have revealed several important unifying traits that make them unique among the chordates, including invariant cell lineages through gastrula stages and an overall morphological simplicity. Gastrulation has only been studied in detail in ascidians such as Ciona and Phallusia, where it involves a simple cup-shaped gastrula driven primarily by endoderm invagination. This appears to differ significantly from vertebrate models, such as Xenopus, in which mesoderm convergent extension and epidermal epiboly are major contributors to involution. These differences may reflect the cellular simplicity of the ascidian embryo.
Asunto(s)
Tipificación del Cuerpo , Embrión no Mamífero/fisiología , Endodermo/fisiología , Gástrula/fisiología , Gastrulación , Regulación del Desarrollo de la Expresión Génica , Urocordados/fisiología , Animales , Linaje de la Célula , Embrión no Mamífero/citología , Evolución Molecular , Gástrula/citología , Morfogénesis , Urocordados/embriologíaRESUMEN
Mesoderm and endoderm internalization in the Xenopus embryo are based on a number of region-specific morphogenetic processes that co-act in the vegetal half of the gastrula. In the multilayered wall surrounding the blastocoel, the apical layer engages in bottle cell formation and associated invagination and involution movements, and in cell intercalation in the plane of the layer. Of these epithelial-type processes, only bottle cell formation has been analyzed mechanistically. In the deep layers of the blastocoel wall, cell-on-cell migration drives the internalization of mesoderm by various forms of involution and of the endodermal cell mass by vegetal rotation. In the mesoderm, cells migrate in a mesenchymal mode with the aid of locomotory protrusions, whereas cells of the vegetal cell mass resemble free bottle cells that engage in ingression-type amoeboid migration. Cells rearrange by differential migration leading to parallel or orthogonal forms of intercalation and respective types of convergent extension. The interaction of the various apical and deep layer processes gives rise to dorsal multilayer invagination, ventrolateral internal involution, peak involution and orthogonal convergent extension of the dorsal posterior mesoderm, vegetal rotation, and blastopore constriction. It is speculated how these multilayer gastrulation movements could be derived from mechanisms in invertebrate single-epithelium gastrulae.
Asunto(s)
Embrión no Mamífero/fisiología , Endodermo/fisiología , Regulación del Desarrollo de la Expresión Génica , Mesodermo/fisiología , Morfogénesis , Proteínas de Xenopus/metabolismo , Xenopus laevis/fisiología , Animales , Movimiento Celular , Embrión no Mamífero/citología , Endodermo/citología , Mesodermo/citología , Transducción de Señal , Proteínas de Xenopus/genética , Xenopus laevis/embriologíaRESUMEN
In birds as in all amniotes, the site of gastrulation is a midline structure, the primitive streak. This appears as cells in the one cell-thick epiblast undergo epithelial-to-mesenchymal transition to ingress and form definitive mesoderm and endoderm. Global movements involving tens of thousands of cells in the embryonic epiblast precede gastrulation. They position the primitive streak precursors from a marginal position (equivalent to the situation in anamniotes) along the future antero-posterior axis (typical for amniotes). These epithelial movements continue in modified form during gastrulation, when they are accompanied by collective movements of different class in the forming mesoderm and endoderm. Here I discuss the nature of these collective cell movements shaping the embryo, their interplay with signaling events controlling fate specification and significance in an evolutionary perspective.
Asunto(s)
Pollos/fisiología , Endodermo/fisiología , Gástrula/fisiología , Gastrulación , Regulación del Desarrollo de la Expresión Génica , Mesodermo/fisiología , Proteínas de Pez Cebra/metabolismo , Animales , Movimiento Celular , Embrión de Pollo , Endodermo/citología , Gástrula/citología , Mesodermo/citología , Transducción de Señal , Proteínas de Pez Cebra/genética , Cigoto/fisiologíaRESUMEN
Gastrulation is a central process in mammalian development in which a spatiotemporally coordinated series of events driven by cross-talk between adjacent embryonic and extra-embryonic tissues results in stereotypical morphogenetic cell behaviors, massive cell proliferation and the acquisition of distinct cell identities. Gastrulation provides the blueprint of the body plan of the embryo, as well as generating extra-embryonic cell types of the embryo to make a connection with its mother. Gastrulation involves the specification of mesoderm and definitive endoderm from pluripotent epiblast, concomitant with a highly ordered elongation of tissue along the anterior-posterior (AP) axis. Interestingly, cells with an endoderm identity arise twice during mouse development. Cells with a primitive endoderm identity are specified in the preimplantation blastocyst, and which at gastrulation intercalate with the emergent definitive endoderm to form a mosaic tissue, referred to as the gut endoderm. The gut endoderm gives rise to the gut tube, which will subsequently become patterned along its AP axis into domains possessing unique visceral organ identities, such as thyroid, lung, liver and pancreas. In this way, proper endoderm development is essential for vital organismal functions, including the absorption of nutrients, gas exchange, detoxification and glucose homeostasis.
Asunto(s)
Embrión de Mamíferos/fisiología , Endodermo/fisiología , Tracto Gastrointestinal/fisiología , Gastrulación , Estratos Germinativos/fisiología , Mesodermo/fisiología , Morfogénesis , Animales , Embrión de Mamíferos/citología , Endodermo/citología , Tracto Gastrointestinal/citología , Estratos Germinativos/citología , Mesodermo/citología , RatonesRESUMEN
The first lineage specification of pluripotent mouse epiblast segregates neuroectoderm (NE) from mesoderm and definitive endoderm (ME) by mechanisms that are not well understood. Here we demonstrate that the induction of ME gene programs critically relies on the T-box transcription factors Eomesodermin (also known as Eomes) and Brachyury, which concomitantly repress pluripotency and NE gene programs. Cells deficient in these T-box transcription factors retain pluripotency and differentiate to NE lineages despite the presence of ME-inducing signals transforming growth factor ß (TGF-ß)/Nodal and Wnt. Pluripotency and NE gene networks are additionally repressed by ME factors downstream of T-box factor induction, demonstrating a redundancy in program regulation to safeguard mutually exclusive lineage specification. Analyses of chromatin revealed that accessibility of ME enhancers depends on T-box factor binding, whereas NE enhancers are accessible and already activation primed at pluripotency. This asymmetry of the chromatin landscape thus explains the default differentiation of pluripotent cells to NE in the absence of ME induction that depends on activating and repressive functions of Eomes and Brachyury.
Asunto(s)
Cromatina/genética , Proteínas Fetales/genética , Estratos Germinativos/fisiología , Células Madre Pluripotentes/fisiología , Proteínas de Dominio T Box/genética , Animales , Diferenciación Celular/genética , Línea Celular , Separación Celular/métodos , Endodermo/fisiología , Femenino , Regulación del Desarrollo de la Expresión Génica/genética , Masculino , Ratones , Placa Neural/fisiología , Factor de Crecimiento Transformador beta/genéticaRESUMEN
Development of treatments for vocal dysphonia has been inhibited by lack of human vocal fold (VF) mucosa models because of difficulty in procuring VF epithelial cells, epithelial cells' limited proliferative capacity and absence of cell lines. Here we report development of engineered VF mucosae from hiPSC, transfected via TALEN constructs for green fluorescent protein, that mimic development of VF epithelial cells in utero. Modulation of FGF signaling achieves stratified squamous epithelium from definitive and anterior foregut derived cultures. Robust culturing of these cells on collagen-fibroblast constructs produces three-dimensional models comparable to in vivo VF mucosa. Furthermore, we demonstrate mucosal inflammation upon exposure of these constructs to 5% cigarette smoke extract. Upregulation of pro-inflammatory genes in epithelium and fibroblasts leads to aberrant VF mucosa remodeling. Collectively, our results demonstrate that hiPSC-derived VF mucosa is a versatile tool for future investigation of genetic and molecular mechanisms underlying epithelium-fibroblasts interactions in health and disease.
Asunto(s)
Células Madre Pluripotentes Inducidas/citología , Membrana Mucosa/crecimiento & desarrollo , Fumar/efectos adversos , Pliegues Vocales/crecimiento & desarrollo , Diferenciación Celular , Línea Celular , Células Cultivadas , Endodermo/fisiología , Factores de Crecimiento de Fibroblastos/metabolismo , Regulación de la Expresión Génica , Genes Reporteros , Genoma , Proteínas Fluorescentes Verdes/metabolismo , Humanos , Células Madre Pluripotentes Inducidas/metabolismo , Inflamación/genética , Inflamación/patología , ARN Mensajero/genética , ARN Mensajero/metabolismo , Transducción de Señal , Ingeniería de TejidosRESUMEN
The endoderm is a progenitor tissue that, in humans, gives rise to the majority of internal organs. Over the past few decades, genetic studies have identified many of the upstream signals specifying endoderm identity in different model systems, revealing them to be divergent from invertebrates to vertebrates. However, more recent studies of the cell behaviours driving endodermal morphogenesis have revealed a surprising number of shared features, including cells undergoing epithelial-to-mesenchymal transitions (EMTs), collective cell migration, and mesenchymal-to-epithelial transitions (METs). In this Review, we highlight how cross-organismal studies of endoderm morphogenesis provide a useful perspective that can move our understanding of this fascinating tissue forward.
Asunto(s)
Linaje de la Célula/fisiología , Endodermo/embriología , Endodermo/fisiología , Morfogénesis/fisiología , Animales , Evolución Biológica , Diferenciación Celular/fisiología , Movimiento Celular/fisiología , Endodermo/citología , Transición Epitelial-Mesenquimal/fisiología , Humanos , Transducción de Señal , Vertebrados/embriologíaRESUMEN
Hydra is a cnidarian polyp with an anatomically simple neuromuscular system that can offer evolutionary insights on the functional design of animal body plans. Using calcium imaging to map the activity of the entire epitheliomuscular system of behaving Hydra, we find seven basic spatiotemporal patterns of muscle activity. Patterns include global and local activation events with widely varying kinetics of initiation and wave-like propagation. The orthogonally oriented endodermal and ectodermal muscle fibers are jointly activated during longitudinal contractions. Individual epitheliomuscular cells can participate in multiple patterns, even with very different kinetics. This cellular multifunctionality could enable the structurally simple epitheliomuscular tissue of basal metazoans to implement a diverse behavioral output.
Asunto(s)
Hydra/fisiología , Animales , Ectodermo/fisiología , Endodermo/fisiología , Músculos/fisiologíaRESUMEN
Following fertilization, totipotent cells undergo asymmetric cell divisions, resulting in three distinct cell types in the late pre-implantation blastocyst: epiblast (Epi), primitive endoderm (PrE), and trophectoderm (TE). Here, we aim to understand whether these three cell types can be induced from fibroblasts by one combination of transcription factors. By utilizing a sophisticated fluorescent knockin reporter system, we identified a combination of five transcription factors, Gata3, Eomes, Tfap2c, Myc, and Esrrb, that can reprogram fibroblasts into induced pluripotent stem cells (iPSCs), induced trophoblast stem cells (iTSCs), and induced extraembryonic endoderm stem cells (iXENs), concomitantly. In-depth transcriptomic, chromatin, and epigenetic analyses provide insights into the molecular mechanisms that underlie the reprogramming process toward the three cell types. Mechanistically, we show that the interplay between Esrrb and Eomes during the reprogramming process determines cell fate, where high levels of Esrrb induce a XEN-like state that drives pluripotency and high levels of Eomes drive trophectodermal fate.
Asunto(s)
Blastocisto/fisiología , Endodermo/fisiología , Fibroblastos/fisiología , Células Madre Pluripotentes Inducidas/fisiología , Trofoblastos/fisiología , Animales , Diferenciación Celular , Linaje de la Célula , Células Cultivadas , Reprogramación Celular , Implantación del Embrión , Ratones , Receptores de Estrógenos/genética , Receptores de Estrógenos/metabolismo , Proteínas de Dominio T Box/genética , Proteínas de Dominio T Box/metabolismo , Factores de Transcripción/metabolismoRESUMEN
The essential roles played by Nodal and Bmp signalling during early mouse development have been extensively documented. Here we use conditional deletion strategies to investigate functional contributions made by Nodal, Bmp and Smad downstream effectors during primordial germ cell (PGC) development. We demonstrate that Nodal and its target gene Eomes provide early instructions during formation of the PGC lineage. We discover that Smad2 inactivation in the visceral endoderm results in increased numbers of PGCs due to an expansion of the PGC niche. Smad1 is required for specification, whereas in contrast Smad4 controls the maintenance and migration of PGCs. Additionally we find that beside Blimp1, down-regulated phospho-Smad159 levels also distinguishes PGCs from their somatic neighbours so that emerging PGCs become refractory to Bmp signalling that otherwise promotes mesodermal development in the posterior epiblast. Thus balanced Nodal/Bmp signalling cues regulate germ cell versus somatic cell fate decisions in the early posterior epiblast.