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Proceedings of the National Academy of... May 2008ATP-dependent chromatin remodeling complexes are a notable group of epigenetic modifiers that use the energy of ATP hydrolysis to change the structure of chromatin,...
ATP-dependent chromatin remodeling complexes are a notable group of epigenetic modifiers that use the energy of ATP hydrolysis to change the structure of chromatin, thereby altering its accessibility to nuclear factors. BAF250a (ARID1a) is a unique and defining subunit of the BAF chromatin remodeling complex with the potential to facilitate chromosome alterations critical during development. Our studies show that ablation of BAF250a in early mouse embryos results in developmental arrest (about embryonic day 6.5) and absence of the mesodermal layer, indicating its critical role in early germ-layer formation. Moreover, BAF250a deficiency compromises ES cell pluripotency, severely inhibits self-renewal, and promotes differentiation into primitive endoderm-like cells under normal feeder-free culture conditions. Interestingly, this phenotype can be partially rescued by the presence of embryonic fibroblast cells. DNA microarray, immunostaining, and RNA analyses revealed that BAF250a-mediated chromatin remodeling contributes to the proper expression of numerous genes involved in ES cell self-renewal, including Sox2, Utf1, and Oct4. Furthermore, the pluripotency defects in BAF250a mutant ES cells appear to be cell lineage-specific. For example, embryoid body-based analyses demonstrated that BAF250a-ablated stem cells are defective in differentiating into fully functional mesoderm-derived cardiomyocytes and adipocytes but are capable of differentiating into ectoderm-derived neurons. Our results suggest that BAF250a is a key component of the gene regulatory machinery in ES cells controlling self-renewal, differentiation, and cell lineage decisions.
Topics: Adipocytes; Animals; Cell Differentiation; Cell Line; Cell Lineage; Cell Proliferation; Chromatin Assembly and Disassembly; Chromosomal Proteins, Non-Histone; DNA-Binding Proteins; Embryo, Mammalian; Embryonic Development; Embryonic Stem Cells; Female; Genes, Developmental; Germ Layers; Male; Mice; Mice, Knockout; Muscle, Skeletal; Myocytes, Cardiac; Nuclear Proteins; Pluripotent Stem Cells; Transcription Factors
PubMed: 18448678
DOI: 10.1073/pnas.0801802105 -
Developmental Biology Aug 2009Amphibian holoblastic cleavage in which all blastomeres contribute to any one of the three primary germ layers has been widely thought to be a developmental pattern in...
Amphibian holoblastic cleavage in which all blastomeres contribute to any one of the three primary germ layers has been widely thought to be a developmental pattern in the stem lineage of vertebrates, and meroblastic cleavage to have evolved independently in each vertebrate lineage. In extant primitive vertebrates, agnathan lamprey and basal bony fishes also undergo holoblastic cleavage, and their vegetal blastomeres have been generally thought to contribute to embryonic endoderm. However, the present marker analyses in basal ray-finned fish bichir and agnathan lamprey embryos indicated that their mesoderm and endoderm develop in the equatorial marginal zone, and their vegetal cell mass is extraembryonic nutritive yolk cells, having non-cell autonomous meso-endoderm inducing activity. Eomesodermin (eomes), but not VegT, orthologs are expressed maternally in these animals, suggesting that VegT is a maternal factor for endoderm differentiation only in amphibian. The study raises the viewpoint that the lamprey/bichir type holoblastic development would have been ancestral to extant vertebrates and retained in their stem lineage; amphibian-type holoblastic development would have been acquired secondarily, accompanied by the exploitation of new molecular machinery such as maternal VegT.
Topics: Animals; Biological Evolution; Body Patterning; Embryo, Nonmammalian; Endoderm; Fishes; Gene Expression Regulation, Developmental; Germ Layers; Lampreys; Larva; Mesoderm; Models, Biological; Phylogeny; Reverse Transcriptase Polymerase Chain Reaction
PubMed: 19433081
DOI: 10.1016/j.ydbio.2009.05.543 -
Developmental Dynamics : An Official... Oct 2015Kruppel-like factors (Klfs) are a family of transcription factors consisting of 17 members in mammals, Klf1-Klf17, which are involved in fundamental cellular...
BACKGROUND
Kruppel-like factors (Klfs) are a family of transcription factors consisting of 17 members in mammals, Klf1-Klf17, which are involved in fundamental cellular physiological procedures, such as cell proliferation, differentiation, and apoptosis. However, their functions in embryonic development have been poorly understood. Our previous study has demonstrated that the pluripotency factor Klf4 participates in germ layer formation and axis patterning of Xenopus embryos by means of the regulation of key developmental signals. In the present study, we further investigated comprehensively the expression and functions of the klf family genes, klf2, klf5, klf6, klf7, klf8, klf11, klf15, and klf17, during the embryogenesis of Xenopus laevis.
RESULTS
Spatio-temporal expression analyses demonstrate that these genes are transcribed both maternally and zygotically in Xenopus embryos, and during organogenesis and tissue differentiation, they are localized to a variety of placodes and tissues. Gain and loss of function studies manifest that Klf factors play different roles in germ layer formation and body axis patterning. Moreover, each Klf factor exhibits distinct regulatory effects on the expression of genes that are essential for germ layer formation and body axis patterning.
CONCLUSIONS
These results suggest that Klf factors are involved in the fine-tuning of these genes during early embryogenesis.
Topics: Animals; Body Patterning; Embryo, Nonmammalian; Embryonic Development; Gene Expression; Gene Knockdown Techniques; Germ Layers; Kruppel-Like Transcription Factors; Multigene Family; Xenopus
PubMed: 26198170
DOI: 10.1002/dvdy.24310 -
Mechanisms of Development Sep 2020During mouse embryonic development a mass of pluripotent epiblast tissue is transformed during gastrulation to generate the three definitive germ layers: endoderm,... (Review)
Review
During mouse embryonic development a mass of pluripotent epiblast tissue is transformed during gastrulation to generate the three definitive germ layers: endoderm, mesoderm, and ectoderm. During gastrulation, a spatiotemporally controlled sequence of events results in the generation of organ progenitors and positions them in a stereotypical fashion throughout the embryo. Key to the correct specification and differentiation of these cell fates is the establishment of an axial coordinate system along with the integration of multiple signals by individual epiblast cells to produce distinct outcomes. These signaling domains evolve as the anterior-posterior axis is established and the embryo grows in size. Gastrulation is initiated at the posteriorly positioned primitive streak, from which nascent mesoderm and endoderm progenitors ingress and begin to diversify. Advances in technology have facilitated the elaboration of landmark findings that originally described the epiblast fate map and signaling pathways required to execute those fates. Here we will discuss the current state of the field and reflect on how our understanding has shifted in recent years.
Topics: Animals; Body Patterning; Cell Differentiation; Cell Lineage; Ectoderm; Embryonic Development; Endoderm; Female; Gastrula; Gastrulation; Germ Layers; Mesoderm; Mice; Organ Specificity; Pregnancy
PubMed: 32473204
DOI: 10.1016/j.mod.2020.103617 -
Mechanisms of Development Apr 2017In most mammals, embryonic development and growth proceed in the maternal uterus. Mouse late blastocyst embryos implant on the uterine epithelium around embryonic day... (Review)
Review
In most mammals, embryonic development and growth proceed in the maternal uterus. Mouse late blastocyst embryos implant on the uterine epithelium around embryonic day (E)4.5, and immediately afterward the whole embryo's shape is dynamically changed from a bowl-like shape to an elongated egg-cylinder until E5.5. Concurrently, mouse anterior-posterior (A-P) axis polarization occurs by the emergence of distal visceral endoderm (DVE) cells at the cellular and molecular levels as the proximal-distal (P-D) axis. The embryonic growth and axis polarization are considered to be controlled primarily by multiple growth factors' signaling. However, the precise cellular mechanisms of DVE formation in which this signaling is involved have been unclear. We recently identified that local breaching of the basement membrane (BM) between the epiblast and the visceral endoderm (VE) at the distal tip allows inner epiblast cells to transmigrate into the outer VE layer as the emergence of DVE cells. More importantly, the local BM loss in the distal region appears to be triggered by mechanical forces exerted from maternal tissues on embryos and embryonic growth itself. Our data suggest a fascinating hypothesis concerning mouse A-P axis polarization mediated by the whole embryo's shape change through mechanical stress between the embryo and the uterine epithelium. Our mechanical model provides a unique insight into why the first axis polarity of the implanted mouse embryo is established in the P-D direction initially and not in the future A-P direction. We also discuss whether the local breaching of the BM mediated by mechanical cues is essential to mouse A-P axis polarization in in vitro culture.
Topics: Animals; Basement Membrane; Body Patterning; Embryo Implantation; Embryo, Mammalian; Female; Gene Expression Regulation, Developmental; Germ Layers; Intercellular Signaling Peptides and Proteins; Mechanotransduction, Cellular; Mice; Pregnancy; Stress, Mechanical; Time Factors; Uterus
PubMed: 27697519
DOI: 10.1016/j.mod.2016.09.002 -
Development (Cambridge, England) Sep 2014The hedgehog (HH) pathway is well known for its mitogenic and morphogenic functions during development, and HH signaling continues in discrete populations of cells... (Review)
Review
The hedgehog (HH) pathway is well known for its mitogenic and morphogenic functions during development, and HH signaling continues in discrete populations of cells within many adult mammalian tissues. Growing evidence indicates that HH regulates diverse quiescent stem cell populations, but the exact roles that HH signaling plays in adult organ homeostasis and regeneration remain poorly understood. Here, we review recently identified functions of HH in modulating the behavior of tissue-specific adult stem and progenitor cells during homeostasis, regeneration and disease. We conclude that HH signaling is a key factor in the regulation of adult tissue homeostasis and repair, acting via multiple different routes to regulate distinct cellular outcomes, including maintenance of plasticity, in a context-dependent manner.
Topics: Adult; Adult Stem Cells; Germ Layers; Hedgehog Proteins; Homeostasis; Humans; Models, Biological; Signal Transduction
PubMed: 25183867
DOI: 10.1242/dev.083691 -
Rif1 Regulates Self-Renewal and Impedes Mesendodermal Differentiation of Mouse Embryonic Stem Cells.Stem Cell Reviews and Reports Jul 2023RAP1 interacting factor 1 (Rif1) is highly expressed in mice embryos and mouse embryonic stem cells (mESCs). It plays critical roles in telomere length homeostasis, DNA...
BACKGROUND
RAP1 interacting factor 1 (Rif1) is highly expressed in mice embryos and mouse embryonic stem cells (mESCs). It plays critical roles in telomere length homeostasis, DNA damage, DNA replication timing and ERV silencing. However, whether Rif1 regulates early differentiation of mESC is still unclear.
METHODS
In this study, we generated a Rif1 conditional knockout mouse embryonic stem (ES) cell line based on Cre-loxP system. Western blot, flow cytometry, quantitative real-time polymerase chain reaction (qRT-PCR), RNA high-throughput sequencing (RNA-Seq), chromatin immunoprecipitation followed high-throughput sequencing (ChIP-Seq), chromatin immunoprecipitation quantitative PCR (ChIP-qPCR), immunofluorescence, and immunoprecipitation were employed for phenotype and molecular mechanism assessment.
RESULTS
Rif1 plays important roles in self-renewal and pluripotency of mESCs and loss of Rif1 promotes mESC differentiation toward the mesendodermal germ layers. We further show that Rif1 interacts with histone H3K27 methyltransferase EZH2, a subunit of PRC2, and regulates the expression of developmental genes by directly binding to their promoters. Rif1 deficiency reduces the occupancy of EZH2 and H3K27me3 on mesendodermal gene promoters and activates ERK1/2 activities.
CONCLUSION
Rif1 is a key factor in regulating the pluripotency, self-renewal, and lineage specification of mESCs. Our research provides new insights into the key roles of Rif1 in connecting epigenetic regulations and signaling pathways for cell fate determination and lineage specification of mESCs.
Topics: Animals; Mice; Mouse Embryonic Stem Cells; Fibrinogen; Cell Differentiation; Cell Line; Germ Layers; Telomere-Binding Proteins
PubMed: 36971904
DOI: 10.1007/s12015-023-10525-1 -
Genes & Development Dec 2012Tight control over the segregation of endoderm, mesoderm, and ectoderm is essential for normal embryonic development of all species, yet how neighboring embryonic...
Tight control over the segregation of endoderm, mesoderm, and ectoderm is essential for normal embryonic development of all species, yet how neighboring embryonic blastomeres can contribute to different germ layers has never been fully explained. We postulated that microRNAs, which fine-tune many biological processes, might modulate the response of embryonic blastomeres to growth factors and other signals that govern germ layer fate. A systematic screen of a whole-genome microRNA library revealed that the let-7 and miR-18 families increase mesoderm at the expense of endoderm in mouse embryonic stem cells. Both families are expressed in ectoderm and mesoderm, but not endoderm, as these tissues become distinct during mouse and frog embryogenesis. Blocking let-7 function in vivo dramatically affected cell fate, diverting presumptive mesoderm and ectoderm into endoderm. siRNA knockdown of computationally predicted targets followed by mutational analyses revealed that let-7 and miR-18 down-regulate Acvr1b and Smad2, respectively, to attenuate Nodal responsiveness and bias blastomeres to ectoderm and mesoderm fates. These findings suggest a crucial role for the let-7 and miR-18 families in germ layer specification and reveal a remarkable conservation of function from amphibians to mammals.
Topics: Animals; Cells, Cultured; DNA Mutational Analysis; Embryonic Development; Embryonic Stem Cells; Gene Expression Regulation, Developmental; Gene Knockdown Techniques; Genome; Germ Layers; Mice; MicroRNAs; Xenopus laevis
PubMed: 23152446
DOI: 10.1101/gad.200758.112 -
Journal of Biomechanics Jan 2010Multicellular organisms are generated by coordinated cell movements during morphogenesis. Convergent extension is a key tissue movement that organizes mesoderm,... (Review)
Review
Multicellular organisms are generated by coordinated cell movements during morphogenesis. Convergent extension is a key tissue movement that organizes mesoderm, ectoderm, and endoderm in vertebrate embryos. The goals of researchers studying convergent extension, and morphogenesis in general, include understanding the molecular pathways that control cell identity, establish fields of cell types, and regulate cell behaviors. Cell identity, the size and boundaries of tissues, and the behaviors exhibited by those cells shape the developing embryo; however, there is a fundamental gap between understanding the molecular pathways that control processes within single cells and understanding how cells work together to assemble multicellular structures. Theoretical and experimental biomechanics of embryonic tissues are increasingly being used to bridge that gap. The efforts to map molecular pathways and the mechanical processes underlying morphogenesis are crucial to understanding: (1) the source of birth defects, (2) the formation of tumors and progression of cancer, and (3) basic principles of tissue engineering. In this paper, we first review the process of tissue convergent extension of the vertebrate axis and then review models used to study the self-organizing movements from a mechanical perspective. We conclude by presenting a relatively simple "wedge-model" that exhibits key emergent properties of convergent extension such as the coupling between tissue stiffness, cell intercalation forces, and tissue elongation forces.
Topics: Animals; Biomechanical Phenomena; Body Patterning; Cell Differentiation; Ectoderm; Embryo, Nonmammalian; Embryonic Development; Germ Layers; Mesoderm; Morphogenesis; Xenopus laevis
PubMed: 19815213
DOI: 10.1016/j.jbiomech.2009.09.010 -
Aging May 2011Aging-associated diseases are often caused by progressive loss or dysfunction of cells that ultimately affect the overall function of tissues and organs. Successful... (Review)
Review
Aging-associated diseases are often caused by progressive loss or dysfunction of cells that ultimately affect the overall function of tissues and organs. Successful treatment of these diseases could benefit from cell-based therapy that would regenerate lost cells or otherwise restore tissue function. Human embryonic stem cells (hESCs) promise to be an important therapeutic candidate in treating aging-associated diseases due to their unique capacity for self-renewal and pluripotency. To date, there are numerous hESC lines that have been developed and characterized. We will discuss how hESC lines are derived, their molecular and cellular properties, and how their ability to differentiate into all three embryonic germ layers is determined. We will also outline the methods currently employed to direct their differentiation into populations of tissue-specific, functional cells. Finally, we will highlight the general challenges that must be overcome and the strategies being developed to generate highly-purified hESC-derived cell populations that can safely be used for clinical applications.
Topics: Aging; Cell Differentiation; Disease; Embryonic Stem Cells; Germ Layers; Humans; Stem Cell Transplantation; Teratoma
PubMed: 21566262
DOI: 10.18632/aging.100328