scholarly journals Interactions between Nodal and Wnt signalling Drive Robust Symmetry-Breaking and Axial Organisation in Gastruloids (Embryonic Organoids)

2016 ◽  
Author(s):  
D.A. Turner ◽  
C.R. Glodowski ◽  
L. Alonso-Crisostomo ◽  
P. Baillie-Johnson ◽  
P.C. Hayward ◽  
...  
Keyword(s):  
Pattern Formation ◽  
Symmetry Breaking ◽  
Cell Fate ◽  
Embryonic Stem ◽  
Early Embryo ◽  
Model System ◽  
Wnt Signalling ◽  
Signalling Pathways ◽  
Cell Fate Decisions ◽  
Three Body

AbstractGeneration of asymmetry within the early embryo is a critical step in the establishment of the three body axes, providing a reference for the patterning of the organism. To study the establishment of asymmetry and the development of the anteroposterior axis (AP) in culture, we utilised our ‘Gastruloid’ model system. ‘Gastruloids’, highly reproducible embryonic organoids formed from aggregates of mouse embryonic stem cells, display symmetry-breaking, polarised gene expression and axial development, mirroring the processes on a time-scale similar to that of the mouse embyro. Using Gastruloids formed from mouse ESCs containing reporters for Wnt, FGF and Nodal signalling, we were able to quantitatively assess the contribution of these signalling pathways to the establishment of asymmetry through single time-point and live-cell fluorescence microscopy.During the first 24-48h of culture, interactions between the Wnt/β-Catenin and Nodal/TGF/β signalling pathways promote the initial symmetry-breaking event, manifested through polarised Brachyury (T/Bra) expression. Neither BMP nor FGF signalling is required for the establishment of asymmetry, however Wnt signalling is essential for the amplification and stability of the initial patterning event. Additionally, low, endogenous levels of FGF (24-48h) has a role in the amplification of the established pattern at later time-points.Our results confirm that Gastruloids behave like epiblast cells in the embryo, leading us to translate the processes and signalling involved in pattern formation of Gastruloids in culture to the development of the embryo, firmly establishing Gastruloids as a highly reproducible, robust model system for studying cell fate decisions and early pattern formation in culture.

scholarly journals Self-organised symmetry breaking in zebrafish reveals feedback from morphogenesis to pattern formation

2019 ◽  
Author(s):  
Vikas Trivedi ◽  
Timothy Fulton ◽  
Andrea Attardi ◽  
Kerim Anlas ◽  
Chaitanya Dingare ◽  
...  
Keyword(s):  
Pattern Formation ◽  
Symmetry Breaking ◽  
Embryonic Stem ◽  
Break Symmetry ◽  
Early Embryo ◽  
Beta Catenin ◽  
Embryonic Cells ◽  
Convergence And Extension ◽  
Extensive Cell ◽  
Anterior Posterior

A fundamental question in developmental biology is how the early embryo breaks initial symmetry to establish the spatial coordinate system later important for the organisation of the embryonic body plan. In zebrafish, this is thought to depend on the inheritance of maternal mRNAs [1–3], cortical rotation to generate a dorsal pole of beta-catenin activity [4–8] and the release of Nodal signals from the yolk syncytial layer (YSL) [9–12]. Recent work aggregating mouse embryonic stem cells has shown that symmetry breaking can occur in the absence of extra-embryonic tissue [19,20]. To test whether this is also true in zebrafish, we separated embryonic cells from the yolk and allowed them to develop as aggregates. These aggregates break symmetry autonomously to form elongated structures with an anterior-posterior pattern. Extensive cell mixing shows that any pre-existing asymmetry is lost prior to the breaking morphological symmetry, revealing that the maternal pre-pattern is not strictly required for early embryo patterning. Following early signalling events after isolation of embryonic cells reveals that a pole of Nodal activity precedes and is required for elongation. The blocking of PCP-dependent convergence and extension movements disrupts the establishment of opposing poles of BMP and Wnt/TCF activity and the patterning of anterior-posterior neural tissue. These results lead us to suggest that convergence and extension plays a causal role in the establishment of morphogen gradients and pattern formation during zebrafish gastrulation.

Position dependent control of cell fate in the Fucus embryo: role of intercellular communication

Development ◽  
1998 ◽  
Vol 125 (11) ◽  
pp. 1999-2008 ◽  
Author(s):  
F.Y. Bouget ◽  
F. Berger ◽  
C. Brownlee
Keyword(s):  
Cell Wall ◽  
Pattern Formation ◽  
Cell Fate ◽  
Intercellular Communication ◽  
Cell Types ◽  
Early Embryo ◽  
Cell Contact ◽  
Dependent Manner ◽  
Intact Cells ◽  
Cell Fate Decisions

The early embryo of the brown alga Fucus comprises two cell types, i. e. rhizoid and thallus which are morphogically and cytologically distinguishable. Previous work has pointed to the cell wall as a source of position-dependent information required for polarisation and fate determination in the zygote and 2-celled embryo. In this study we have analysed the mechanism(s) of cell fate control and pattern formation at later embryonic stages using a combination of laser microsurgery and microinjection. The results indicate that the cell wall is required for maintenance of pre-existing polarity in isolated intact cells. However, all cell types ultimately have the capacity to re-differentiate or regenerate rhizoid cells in response to ablation of neighbouring cells. This regeneration is regulated in a position-dependent manner and is strongly influenced by intercellular communication, probably involving transport or diffusion of inhibitory signals which appear to be essential for regulation of cell fate decisions. This type of cell-to-cell communication does not involve symplastic transport or direct cell-cell contact inhibition. Apoplastic diffusible gradients appear to be involved in pattern formation in the multicellular embryo.

scholarly journals Early Cell Fate Decisions of Human Embryonic Stem Cells and Mouse Epiblast Stem Cells Are Controlled by the Same Signalling Pathways

PLoS ONE ◽  
2009 ◽  
Vol 4 (6) ◽  
pp. e6082 ◽  
Author(s):  
Ludovic Vallier ◽  
Thomas Touboul ◽  
Zhenzhi Chng ◽  
Minodora Brimpari ◽  
Nicholas Hannan ◽  
...  
Keyword(s):  
Stem Cells ◽  
Embryonic Stem Cells ◽  
Cell Fate ◽  
Human Embryonic Stem Cells ◽  
Embryonic Stem ◽  
Signalling Pathways ◽  
Cell Fate Decisions ◽  
Epiblast Stem Cells

scholarly journals Inhibition of Wnt signalling by Notch via two distinct mechanisms

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ahmet Acar ◽  
Ana Hidalgo-Sastre ◽  
Michael K. Leverentz ◽  
Christopher G. Mills ◽  
Simon Woodcock ◽  
...  
Keyword(s):  
Cell Fate ◽  
Membrane Fraction ◽  
Transcriptional Activity ◽  
Cell Types ◽  
Wnt Signalling ◽  
Signalling Pathways ◽  
Adult Tissue ◽  
Cell Fate Decisions ◽  
Dsl Ligands ◽  
Opposing Effects

AbstractNotch and Wnt are two essential signalling pathways that help to shape animals during development and to sustain adult tissue homeostasis. Although they are often active at the same time within a tissue, they typically have opposing effects on cell fate decisions. In fact, crosstalk between the two pathways is important in generating the great diversity of cell types that we find in metazoans. Several different mechanisms have been proposed that allow Notch to limit Wnt signalling, driving a Notch-ON/Wnt-OFF state. Here we explore these different mechanisms in human cells and demonstrate two distinct mechanisms by which Notch itself, can limit the transcriptional activity of β-catenin. At the membrane, independently of DSL ligands, Notch1 can antagonise β-catenin activity through an endocytic mechanism that requires its interaction with Deltex and sequesters β-catenin into the membrane fraction. Within the nucleus, the intracellular domain of Notch1 can also limit β-catenin induced transcription through the formation of a complex that requires its interaction with RBPjκ. We believe these mechanisms contribute to the robustness of cell-fate decisions by sharpening the distinction between opposing Notch/Wnt responses.

scholarly journals An interplay between extracellular signalling and the dynamics of the exit from pluripotency drives cell fate decisions in mouse ES cells

2013 ◽  
Author(s):  
David A Turner ◽  
Jamie Trott ◽  
Penelope Hayward ◽  
Pau Rué ◽  
Alfonso Martinez Arias
Keyword(s):  
Cell Fate ◽  
Neural Development ◽  
Es Cells ◽  
Initial Period ◽  
Embryonic Stem ◽  
Primitive Streak ◽  
Wnt Signalling ◽  
Dependent Manner ◽  
Cell Fate Decisions ◽  
Mouse Es Cells

Embryonic Stem cells derived from the epiblast tissue of the mammalian blastocyst retain the capability to differentiate into any adult cell type and are able to self-renew indefinitely under appropriate culture conditions. Despite the large amount of knowledge that we have accumulated to date about the regulation and control of self-renewal, efficient directed differentiation into specific tissues remains elusive. In this work, we have analysed in a systematic manner the interaction between the dynamics of loss of pluripotency and Activin/Nodal, BMP4 and Wnt signalling in fate assignment during the early stages of differentiation of mouse ES cells in culture. During the initial period of differentiation, cells exit from pluripotency and enter an Epi-like state. Following this transient stage, and under the influence of Activin/Nodal and BMP signalling, cells face a fate choice between differentiating into neuroectoderm and contributing to Primitive Streak fates. We find that Wnt signalling does not suppress neural development as previously thought and that it aids both fates in a context dependent manner. Our results suggest that as cells exit pluripotency they are endowed with a primary neuroectodermal fate and that the potency to become endomesodermal rises with time. We suggest that this situation translates into a ?race for fates? in which the neuroectodermal fate has an advantage.

scholarly journals Inhibition of Wnt signalling by Notch via two distinct mechanisms

2020 ◽  
Author(s):  
Ahmet Acar ◽  
Ana Hidalgo-Sastre ◽  
Michael K. Leverentz ◽  
Christopher G. Mills ◽  
Simon Woodcock ◽  
...  
Keyword(s):  
Cell Fate ◽  
Membrane Fraction ◽  
Transcriptional Activity ◽  
Cell Types ◽  
Wnt Signalling ◽  
Signalling Pathways ◽  
Adult Tissue ◽  
Cell Fate Decisions ◽  
Dsl Ligands ◽  
Opposing Effects

SummaryNotch and Wnt are two essential signalling pathways that help to shape animals during development and to sustain adult tissue homeostasis. Although, they are often active at the same time within a tissue, they typically have opposing effects on cell fate decisions. In fact, crosstalk between the two pathways is important in generating the great diversity of cell types that we find in metazoans. However, several different mechanisms have been proposed that allow Notch to limit Wnt signalling, driving a Notch-ON/Wnt-OFF state. Here we explore these different mechanisms in vertebrate cells and demonstrate two distinct mechanisms by which Notch itself, can limit the transcriptional activity of β-catenin. At the membrane, independently of DSL ligands, Notch1 can antagonise β-catenin activity through an endocytosis mediated mechanism that is dependent upon its interaction with Deltex and sequesters β-catenin into the membrane fraction. Within the nucleus, the intracellular domain of Notch1 can also limit β-catenin induced transcription through the formation of a complex that requires its interaction with RBPjκ. We believe these mechanisms contribute to the robustness of cell-fate decisions by sharpening the distinction between opposing Notch/Wnt responses.

scholarly journals Prediction and control of symmetry breaking in embryoid bodies by environment and signal integration

2018 ◽  
Author(s):  
Naor Sagy ◽  
Shaked Slovin ◽  
Maya Allalouf ◽  
Maayan Pour ◽  
Gaya Savyon ◽  
...  
Keyword(s):  
Symmetry Breaking ◽  
Cell Fate ◽  
Developmental Process ◽  
Primitive Streak ◽  
Early Embryo ◽  
Embryoid Bodies ◽  
Neighboring Cell ◽  
Contact Points

AbstractDuring early embryogenesis, mechanical signals, localized biochemical signals and neighboring cell layers interaction coordinate around anteroposterior axis determination and symmetry breaking. Deciphering their relative roles, which are hard to tease apart in vivo, will enhance our understanding of how these processes are driven. In recent years, in vitro 3D models of early mammalian development, such as embryoid bodies (EBs) and gastruloids, were successful in mimicking various aspects of the early embryo, providing high throughput accessible systems for studying the basic rules shaping cell fate and morphology during embryogenesis. Using Brachyury (Bry), a primitive streak and mesendoderm marker in EBs, we study how contact, biochemical and neighboring cell cues affect the positioning of a primitive streak-like locus, determining the AP axis. We show that a Bry-competent layer must be formed in the EB before Bry expression initiates, and that Bry onset locus selection depends on contact points of the EB with its surrounding. We can maneuver Bry onset to occur at a specific locus, a few loci, or in an isotropic peripheral pattern. By spatially separating contact and biochemical signal sources, we show these two modalities can be integrated by the EB to generate a single Bry locus. Finally, we show Foxa2+ cells are predictive of the future location of Bry onset, demonstrating an earlier symmetry-breaking event. By delineating the temporal signaling pathway dependencies of Bry and Foxa2, we were able to selectively abolish either, or spatially decouple the two cell types during EB differentiation. These findings demonstrate multiple inputs integration during an early developmental process, and may prove valuable in directing in vitro differentiation.

scholarly journals Gastruloids develop the three body axes in the absence of extraembryonic tissues and spatially localised signalling

2017 ◽  
Author(s):  
D.A. Turner ◽  
L. Alonso-Crisostomo ◽  
M. Girgin ◽  
P. Baillie-Johnson ◽  
C. R. Glodowski ◽  
...  
Keyword(s):  
Embryonic Stem ◽  
Model System ◽  
The Body ◽  
Genetic Studies ◽  
Animal Development ◽  
Embryonic Tissues ◽  
Bmp Signalling ◽  
Three Body ◽  
Extraembryonic Tissues

AbstractEstablishment of the three body axes is a critical step during animal development. In mammals, genetic studies have shown that a combination of precisely deployed signals from extraembryonic tissues position the anteroposterior axis (AP) within the embryo and lead to the emergence of the dorsoventral (DV) and left-right (LR) axes. We have used Gastruloids, embryonic organoids, as a model system to understand this process and find that they are able to develop AP, DV and LR axes as well as to undergo axial elongation in a manner that mirror embryos. The Gastruloids can be grown for 160 hours and form derivatives from ectoderm, mesoderm and endoderm. We focus on the AP axis and show that in the Gastruloids this axis is registered in the expression of T/Bra at one pole that corresponds to the tip of the elongation. We find that localisation of T/Bra expression depends on the combined activities of Wnt/β-Catenin and Nodal/Smad2,3 signalling, and that BMP signalling is dispensable for this process. Furthermore, AP axis specification occurs in the absence of both extraembryonic tissues and of localised sources of signalling. Our experiments show that Nodal, together with Wnt/β-Catenin signalling, is essential for the expression of T/Bra but that Wnt signalling has a separable activity in the elongation of the axis. The results lead us to suggest that, in the embryo, the role of the extraembryonic tissues might not be to induce the axes but to bias an intrinsic ability of the embryo to break its initial symmetry and organise its axes.One sentence summaryCulture of aggregates of defined number of Embryonic Stem cells leads to self-organised embryo-like structures which, in the absence of localised signalling from extra embryonic tissues and under the autonomous influence of Wnt and Nodal signalling, develop the three main axes of the body.

scholarly journals Regulated Fluctuations in Nanog Expression Mediate Cell Fate Decisions in Embryonic Stem Cells

PLoS Biology ◽  
2009 ◽  
Vol 7 (7) ◽  
pp. e1000149 ◽  
Author(s):  
Tibor Kalmar ◽  
Chea Lim ◽  
Penelope Hayward ◽  
Silvia Muñoz-Descalzo ◽  
Jennifer Nichols ◽  
...  
Keyword(s):  
Stem Cells ◽  
Embryonic Stem Cells ◽  
Cell Fate ◽  
Embryonic Stem ◽  
Cell Fate Decisions ◽  
Nanog Expression ◽  
Mediate Cell
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