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Mechanisms of Development Sep 2020Among the basally branching metazoans, cnidarians display well-defined gastrulation processes leading to a diploblastic body plan, consisting of an endodermal and an... (Review)
Review
Among the basally branching metazoans, cnidarians display well-defined gastrulation processes leading to a diploblastic body plan, consisting of an endodermal and an ectodermal cell layer. As the outgroup to all Bilateria, cnidarians are an interesting group to investigate ancestral developmental mechanisms. Interestingly, all known gastrulation mechanisms known in Bilateria are already found in different species of Cnidaria. Here I review the morphogenetic processes found in different Cnidaria and focus on the investigation of the cellular and molecular mechanisms in the sea anemone Nematostella vectensis, which has been a major model organism among cnidarians for evolutionary developmental biology. Many of the genes involved in germ layer specification and morphogenetic processes in Bilateria are also found active during gastrulation of Nematostella and other cnidarians, suggesting an ancestral role of this process. The molecular analyses indicate a tight link between gastrulation and axis patterning processes by Wnt and FGF signaling. Interestingly, the endodermal layer displays many features of the mesodermal layer in Bilateria, while the pharyngeal ectoderm has an endodermal expression profile. Comparative analyses as well as experimental studies using embryonic aggregates suggest that minor differences in the gene regulatory networks allow the embryo to transition relatively easily from one mode of gastrulation to another.
Topics: Animals; Body Patterning; Cnidaria; Ectoderm; Embryo, Nonmammalian; Endoderm; Gastrulation; Gene Expression Regulation, Developmental; Gene Regulatory Networks; Germ Layers; Mesoderm; Sea Anemones; Signal Transduction
PubMed: 32603823
DOI: 10.1016/j.mod.2020.103628 -
Experimental Hematology Sep 2005Embryonic stem (ES) cells have the potential to develop into all cell types of the adult body. This capability provides the basis for considering the ES cell system as a... (Review)
Review
Embryonic stem (ES) cells have the potential to develop into all cell types of the adult body. This capability provides the basis for considering the ES cell system as a novel and unlimited source of cells for replacement therapies for the treatment of a wide range of diseases. Before the cell-based therapy potential of ES cells can be realized, a better understanding of the pathways regulating lineage-specific differentiation is required. Current studies suggest that the bone morphogenic protein, transforming growth factor-beta, Wnt, and fibroblast growth factor pathways that are required for gastrulation and germ layer induction in the embryo are also essential for differentiation of ES cells in culture. The current understanding of how these factors influence germ layer induction in both the embryo and in the ES cell differentiation system is addressed in this review.
Topics: Animals; Embryonic Development; Embryonic Induction; Germ Layers; Growth Substances; Mice; Signal Transduction; Stem Cells
PubMed: 16140142
DOI: 10.1016/j.exphem.2005.06.009 -
Biochemical Society Transactions Dec 2022The interplay of signalling input and downstream transcriptional activity is the key molecular attribute driving the differentiation of germ layer tissue and the... (Review)
Review
The interplay of signalling input and downstream transcriptional activity is the key molecular attribute driving the differentiation of germ layer tissue and the specification of cell lineages within each germ layer during gastrulation. This review delves into the current understanding of signalling and transcriptional control of lineage development in the germ layers of mouse embryo and non-human primate embryos during gastrulation and highlights the inter-species conservation and divergence of the cellular and molecular mechanisms of germ layer development in the human embryo.
Topics: Mice; Animals; Gastrulation; Cell Lineage; Germ Layers; Cell Differentiation; Embryo, Mammalian; Mammals
PubMed: 36398790
DOI: 10.1042/BST20220256 -
Medical Oncology (Northwood, London,... Sep 2022Cancer signaling pathways defining cell fates are related to differentiation. During the developmental process, three germ layers (endoderm, mesoderm, and ectoderm) are...
Cancer signaling pathways defining cell fates are related to differentiation. During the developmental process, three germ layers (endoderm, mesoderm, and ectoderm) are formed during embryonic development that differentiate into organs via the epigenetic regulation of specific genes. To examine the relationship, the specificities of cancer gene mutations that depend on the germ layers are studied. The major organs affected by cancer were determined based on statistics from the National Cancer Information Center of Korea, and were grouped according to their germ layer origins. Then, the gene mutation frequencies were evaluated to identify any bias based on the differentiation group using the Catalogue of Somatic Mutations in Cancer (COSMIC) database. The chi-square test showed that the p-value of 152 of 166 genes was less than 0.05, and 151 genes showed p-values of less than 0.05 even after adjusting for the false discovery rate (FDR). The germ layer-specific genes were evaluated using visualization based on basic statistics, and the results matched the top ranking genes depending on organs in the COSMIC database.The current study confirmed the germ layer specificity of major cancer genes. The germ layer specificity of mutated driver genes is possibly important in cancer treatments because each mutated gene may react differently depending on the germ layer of origin. By understanding the mechanism of gene mutation in the development and progression of cancer in the context of cell-fate pathways, a more effective therapeutic strategy for cancer can be established.
Topics: Databases, Factual; Epigenesis, Genetic; Female; Genes, Neoplasm; Germ Layers; Humans; Mutation; Neoplasms; Pregnancy
PubMed: 36175592
DOI: 10.1007/s12032-022-01823-8 -
Science China. Life Sciences Apr 2015The African clawed frog, Xenopus laevis, has long been a model animal for the studies in the fields of animal cloning, developmental biology, biochemistry, cell biology,... (Review)
Review
The African clawed frog, Xenopus laevis, has long been a model animal for the studies in the fields of animal cloning, developmental biology, biochemistry, cell biology, and physiology. With the aid of Xenopus, major molecular mechanisms that are involved in embryonic development have been understood. Germ layer formation is the first event of embryonic cellular differentiation, which is induced by a few key maternal factors and subsequently by zygotic signals. Meanwhile, another type of signals, the pluripotency factors in ES cells, which maintain the undifferentiated state, are also present during early embryonic cells. In this review, the functions of the pluripotency factors during Xenopus germ layer formation and the regulatory relationship between the signals that promote differentiation and pluripotency factors are discussed.
Topics: Animals; Cell Differentiation; Embryonic Development; Germ Layers; Pluripotent Stem Cells; Xenopus laevis
PubMed: 25862657
DOI: 10.1007/s11427-015-4799-2 -
Behavioural Neurology 2021Peripheral nerve injuries (PNIs) are some of the most common types of traumatic lesions affecting the nervous system. Although the peripheral nervous system has a higher... (Review)
Review
Peripheral nerve injuries (PNIs) are some of the most common types of traumatic lesions affecting the nervous system. Although the peripheral nervous system has a higher regenerative ability than the central nervous system, delayed treatment is associated with disturbances in both distal sensory and functional abilities. Over the past decades, adult stem cell-based therapies for peripheral nerve injuries have drawn attention from researchers. This is because various stem cells can promote regeneration after peripheral nerve injuries by differentiating into neural-line cells, secreting various neurotrophic factors, and regulating the activity of Schwann cells (SCs). This article reviewed research from the past 10 years on the role of stem cells in the repair of PNIs. We concluded that adult stem cell-based therapies promote the regeneration of PNI in various ways.
Topics: Adult Stem Cells; Germ Layers; Humans; Nerve Regeneration; Peripheral Nerve Injuries; Schwann Cells
PubMed: 34539934
DOI: 10.1155/2021/5586523 -
Cell Stem Cell Jun 2023The emergence of the three germ layers and the lineage-specific precursor cells orchestrating organogenesis represent fundamental milestones during early embryonic...
The emergence of the three germ layers and the lineage-specific precursor cells orchestrating organogenesis represent fundamental milestones during early embryonic development. We analyzed the transcriptional profiles of over 400,000 cells from 14 human samples collected from post-conceptional weeks (PCW) 3 to 12 to delineate the dynamic molecular and cellular landscape of early gastrulation and nervous system development. We described the diversification of cell types, the spatial patterning of neural tube cells, and the signaling pathways likely involved in transforming epiblast cells into neuroepithelial cells and then into radial glia. We resolved 24 clusters of radial glial cells along the neural tube and outlined differentiation trajectories for the main classes of neurons. Lastly, we identified conserved and distinctive features across species by comparing early embryonic single-cell transcriptomic profiles between humans and mice. This comprehensive atlas sheds light on the molecular mechanisms underlying gastrulation and early human brain development.
Topics: Humans; Mice; Animals; Gastrulation; Germ Layers; Cell Differentiation; Organogenesis; Brain
PubMed: 37192616
DOI: 10.1016/j.stem.2023.04.016 -
Development, Growth & Differentiation Sep 2021Germ layer formation is driven by embryonic cell sorting during the early developmental stages. Starfish (Patiria pectinifera) embryos have a connected endoderm and...
Germ layer formation is driven by embryonic cell sorting during the early developmental stages. Starfish (Patiria pectinifera) embryos have a connected endoderm and ectoderm, albeit with few contact surfaces between the epithelia. To better understand the association between cell sorting and germ layer formation, we reconstructed P. pectinifera embryos and examined their germ layer formation. Initial observations showed that the presumptive endodermal (pEN) and presumptive ectodermal (pEC) portions of the embryonic body at the late-blastula stage were preserved throughout development. Based on this, cells that were dissociated from each dermal fragment were mixed in a reconstruction experiment. Our results showed that the pEN and pEC cells were located inside and outside the reaggregates, respectively, to form an embryonic body containing two epithelial layers, separated by a blastocoel. During this process, the pEN cells were motile and shifted from smaller clumps to form a large clump. In contrast, in reaggregates formed in separate cultures, the pEN cells showed strong adhesion abilities, whereas the pEC cells underwent epithelialization. Unlike that in pEN cells, the reaggregation of pEC cells preceded cadherin expression. Filamentous actin was similarly observed in both reaggregates. These results suggest that during the reconstruction of starfish embryos, germ layer formation occurs via the sorting of pEN and pEC cells, depending on their adhesiveness, motility, and epithelialization. In vivo, these properties might embody the physiological significance of cell adhesion in the germ layers constituting the epithelial monolayer.
Topics: Animals; Cell Adhesion; Ectoderm; Endoderm; Germ Layers; Starfish
PubMed: 34480340
DOI: 10.1111/dgd.12749 -
Cell Stem Cell Jan 2022Human organoid model systems lack important cell types that, in the embryo, are incorporated into organ tissues during development. We developed an organoid assembly...
Human organoid model systems lack important cell types that, in the embryo, are incorporated into organ tissues during development. We developed an organoid assembly approach starting with cells from the three primary germ layers-enteric neuroglial, mesenchymal, and epithelial precursors-that were derived separately from human pluripotent stem cells (PSCs). From these three cell types, we generated human antral and fundic gastric tissue containing differentiated glands surrounded by layers of smooth muscle containing functional enteric neurons that controlled contractions of the engineered antral tissue. Using this experimental system, we show that human enteric neural crest cells (ENCCs) promote mesenchyme development and glandular morphogenesis of antral stomach organoids. Moreover, ENCCs can act directly on the foregut to promote a posterior fate, resulting in organoids with a Brunner's gland phenotype. Thus, germ layer components that are derived separately from PSCs can be used for tissue engineering to generate complex human organoids.
Topics: Cell Differentiation; Endoderm; Humans; Neural Crest; Organoids; Pluripotent Stem Cells
PubMed: 34856121
DOI: 10.1016/j.stem.2021.10.010 -
Methods in Molecular Biology (Clifton,... 2022Human pluripotent stem cells have a wide variety of potential applications, ranging from clinical translation to in vitro disease modeling. However, there is significant...
Human pluripotent stem cells have a wide variety of potential applications, ranging from clinical translation to in vitro disease modeling. However, there is significant variation in the potential of individual cell lines to differentiate towards each of the three germ layers as a result of (epi)genetic background, culture conditions, and other factors. We describe here in detail a methodology to evaluate this bias using short directed differentiation towards neuroectoderm, mesendoderm, and definitive endoderm in combination with quantification by RT-qPCR and immunofluorescent stains.
Topics: Cell Differentiation; Endoderm; Germ Layers; Humans; Neural Plate; Pluripotent Stem Cells
PubMed: 35507155
DOI: 10.1007/978-1-0716-1979-7_5