A Novel Biomimetic Model for Studying Mechanics of Embryonic Morphogenesis and Differentiation

2010 ◽  
Author(s):  
Julia A. Henkels ◽  
Evan A. Zamir
Keyword(s):  
Epithelial To Mesenchymal Transition ◽  
Primitive Streak ◽  
Mitotic Cell ◽  
Embryonic Cells ◽  
Mesenchymal Transition ◽  
Genetics Research ◽  
Undifferentiated Cells ◽  
Organizing Center ◽  
Important Time ◽  
Anterior Posterior

Before the explosion of genetics research in the last century, embryonic development was largely studied from a mechanical perspective. Paired with genetic advances in understanding developmental signaling pathways and induction mechanisms, an important goal for understanding morphogenesis is to discover how the genome codes for changes in the mechanical movements of the embryonic cells. After formation of the zygote, a phase of rapid mitotic cell division is followed by epithelialization resulting in a cohesive sheet of cells termed the epiblast. During the next major phase of triploblastic development called gastrulation, a group of undifferentiated cells in the epiblast moves collectively to the embryonic midline and eventually gives rise to the three primary germ layers: endoderm, mesoderm, and ectoderm. At the primitive streak—the “organizing center” in amniotes (reptiles, birds, and mammals) which delineates anterior-posterior polarity—prospective endodermal and mesodermal precursors undergo epithelial-to-mesenchymal transition (EMT), internalization, and eventually organogenesis. “It is not birth, marriage, or death, but gastrulation which is truly the most important time in your life” (Lewis Wolpert, 1986).

scholarly journals BMP4-induced symmetry breaking in a 3D model of the human epiblast

2019 ◽  
Author(s):  
Mijo Simunovic ◽  
Ali H. Brivanlou ◽  
Eric D. Siggia
Keyword(s):  
Live Cell Imaging ◽  
3D Model ◽  
Epithelial To Mesenchymal Transition ◽  
Cell Imaging ◽  
Embryonic Stem ◽  
Primitive Streak ◽  
Mesenchymal Transition ◽  
Pluripotency Markers ◽  
Anterior Posterior

Abstract We describe the protocol of generating a 3D stem-cell-based model of the human pre-gastrulation epiblast by culturing human embryonic stem cells in a mix of hydrogel and Matrigel. Much like the epiblast of an in vitro attached day-10 human embryo, this model is an epithelial sphere with a cavity at its center, it is expressing key pluripotency markers, and it displays apico-basal polarity. The 3D colonies can further be differentiated with morphogens and in the case of intermediate concentrations of BMP4, they break the anterior-posterior symmetry characterized by an asymmetric expression of a primitive streak marker and showing signs of epithelial to mesenchymal transition. The protocol described here is suitable for immunofluorescence staining and for live-cell imaging.

scholarly journals Molecular mechanism of symmetry breaking in a 3D model of a human epiblast

2018 ◽  
Author(s):  
Mijo Simunovic ◽  
Jakob J. Metzger ◽  
Fred Etoc ◽  
Anna Yoney ◽  
Albert Ruzo ◽  
...  
Keyword(s):  
Symmetry Breaking ◽  
Axial Symmetry ◽  
3D Model ◽  
Epithelial To Mesenchymal Transition ◽  
Embryonic Stem ◽  
Primitive Streak ◽  
Molecular Evidence ◽  
Axis Formation ◽  
Mesenchymal Transition

ABSTRACTBreaking the anterior-posterior (AP) symmetry in mammals takes place at gastrulation. Much of the signaling network underlying this process has been elucidated in the mouse, however there is no direct molecular evidence of events driving axis formation in humans. Here, we use human embryonic stem cells to generate an in vitro 3D model of a human epiblast whose size, cell polarity, and gene expression are similar to a 10-day human epiblast. A defined dose of bone mor-phogenetic protein 4 (BMP4) spontaneously breaks axial symmetry, and induces markers of the primitive streak and epithelial to mesenchymal transition. By gene knockouts and live-cell imaging we show that, downstream of BMP4, WNT3 and its inhibitor DKK1 play key roles in this process. Our work demonstrates that a model human epiblast can break axial symmetry despite no asymmetry in the initial signal and in the absence of extraembryonic tissues or maternal cues. Our 3D model opens routes to capturing molecular events underlying axial symmetry breaking phenomena, which have largely been unexplored in model human systems.

scholarly journals Mouse primitive streak forms in situ by initiation of epithelial to mesenchymal transition without migration of a cell population

2011 ◽  
Vol 241 (2) ◽  
pp. 270-283 ◽  
Author(s):  
Margot Williams ◽  
Carol Burdsal ◽  
Ammasi Periasamy ◽  
Mark Lewandoski ◽  
Ann Sutherland
Keyword(s):  
Cell Population ◽  
Epithelial To Mesenchymal Transition ◽  
Primitive Streak ◽  
Mesenchymal Transition ◽  
A Cell

scholarly journals Self-organization of a functional human organizer by combined WNT and NODAL signalling

2017 ◽  
Author(s):  
I. Martyn ◽  
T.Y. Kanno ◽  
A. Ruzo ◽  
E.D. Siggia ◽  
A.H. Brivanlou
Keyword(s):  
Epithelial To Mesenchymal Transition ◽  
Embryonic Stem ◽  
Primitive Streak ◽  
Model Organisms ◽  
Detailed Characterization ◽  
Mesenchymal Transition ◽  
Neural Fate ◽  
Secondary Axis ◽  
Human Embryology ◽  
Emt Markers

In amniotes, the development of the primitive streak (PS) and its accompanying “organizer” define the first stages of gastrulation. Despite detailed characterization in model organisms, the analogous human structures remain a mystery. We have previously shown that when stimulated with BMP4, micropatterned colonies of human embryonic stem cells (hESCs) self-organize to generate early embryonic germ layers1. Here we show that in the same type of colonies WNT signalling is sufficient to induce a PS, and WNT with ACTIVIN is sufficient to induce an organizer, as characterized by embryo-like sharp boundary formation, epithelial-to-mesenchymal transition (EMT) markers, and expression of the organizer specific transcription factor GSC. Moreover, when grafted into chick embryos, WNT and ACTIVIN treated human cells induce and contribute autonomously to a secondary axis while inducing neural fate in the host. This fulfills the most stringent functional criteria for an organizer, and its discovery represents a major milestone in human embryology.

Conditional activation of RhoA suppresses the epithelial to mesenchymal transition at the primitive streak during mouse gastrulation

2004 ◽  
Vol 318 (3) ◽  
pp. 665-672 ◽  
Author(s):  
Toshimitsu Fuse ◽  
Yoshiakira Kanai ◽  
Masami Kanai-Azuma ◽  
Misao Suzuki ◽  
Kazuhiro Nakamura ◽  
...  
Keyword(s):  
Epithelial To Mesenchymal Transition ◽  
Primitive Streak ◽  
Mesenchymal Transition

scholarly journals Cadherin-11 is required for neural crest determination and survival

2020 ◽  
Author(s):  
Subrajaa Manohar ◽  
Alberto Camacho ◽  
Crystal D. Rogers
Keyword(s):  
Cell Migration ◽  
Neural Crest ◽  
Neural Tube ◽  
Epithelial To Mesenchymal Transition ◽  
Congenital Defects ◽  
Embryonic Cells ◽  
Developmental Defects ◽  
Mesenchymal Transition ◽  
Dorsal Neural Tube ◽  
And Migration

AbstractNeural crest (NC) cells are multipotent embryonic cells that form melanocytes, craniofacial bone and cartilage, and the peripheral nervous system in vertebrates. NC cells express many cadherin proteins, which control their specification, epithelial to mesenchymal transition (EMT), migration, and mesenchymal to epithelial transition. Abnormal NC development leads to congenital defects including craniofacial clefts as well as NC-derived cancers. Here, we identify the role of the type II cadherin protein, Cadherin-11 (CDH11), in early chicken NC development. CDH11 is crucial for NC cell migration in amphibian embryos and is linked to cell survival, proliferation, and migration in cancer cells. It has been linked to the complex neurocristopathy disorder, Elsahy‐Waters Syndrome, in humans. Using immunohistochemistry (IHC), we determined that CDH11 protein has dynamic expression that is first co-localized with neural progenitors in early embryos and subsequently upregulated specifically in NC cells as they are specified in the dorsal neural tube prior to migration. We identified that loss of CDH11 led to a reduction of bonafide NC cells in the dorsal neural tube combined with defects in cell migration and survival. Loss of CDH11 increased p53-mediated programmed-cell death, and blocking the p53 pathway rescued the NC phenotype. Our findings demonstrate an early requirement for CDH11 in NC development, and may increase our understanding of early cadherin-related NC developmental defects.SummaryChicken Cadherin-11 (CDH11), which is expressed in neural crest (NC) cells prior to NC cell migration, is necessary for the determination and survival of the premigratory NC population.

scholarly journals An asymmetry in the frequency and position of mitosis in the epiblast precedes gastrulation and suggests a role for mitotic rounding in cell delamination during primitive streak epithelial-mesenchymal transition

2020 ◽  
Author(s):  
Evangéline Despin-Guitard ◽  
Navrita Mathiah ◽  
Matthew Stower ◽  
Wallis Nahaboo ◽  
Elif Sema Eski ◽  
...  
Keyword(s):  
Epithelial Mesenchymal Transition ◽  
Primitive Streak ◽  
Time Lapse ◽  
Mitotic Cell ◽  
Mesenchymal Transition ◽  
Daughter Cells ◽  
Apical Side ◽  
Basal Pole ◽  
Cell Shapes ◽  
Time Lapse Imaging

ABSTRACTThe epiblast, a pseudostratified epithelium, is the precursor for the three main germ layers required for body shape and organogenesis: ectoderm, mesoderm, and endoderm. At gastrulation, a subpopulation of epiblast cells constitutes a transient posteriorly located structure called the primitive streak, where cells that undergo epithelial-mesenchymal transition make up the mesoderm and endoderm lineages.In order to observe the behavior of individual cells, epiblast cells were labeled ubiquitously or in a mosaic fashion using fluorescent membrane reporters. The cell shapes of individual cells and the packing and behaviour of neighbouring cells during primitive streak formation were recorded through live time-lapse imaging. Posterior epiblast displayed a higher frequency of rosettes, a signature of cell rearrangements, prior to primitive streak initiation. A third of rosettes were associated with a central cell undergoing mitosis. Interestingly, cells at the primitive streak, in particular delaminating cells, underwent mitosis twice more frequently than other epiblast cells, suggesting a role for cell division in epithelial-mesenchymal transition. Pseudostratified epithelia are characterized by interkinetic nuclear migration, where mitosis occurs at the apical side of the epithelium. However, we found that exclusively on the posterior side of the epiblast, mitosis was not restricted to the apical side. Non-apical mitosis was apparent as early as E5.75, just after the establishment of the anterior-posterior axis, and prior to initiation of epithelial-mesenchymal transition. Non-apical mitosis was associated with primitive streak morphogenesis, as it occurred specifically in the streak even when ectopically located. Most non-apical mitosis resulted in one or two daughter cells leaving the epiblast layer to become mesoderm. Furthermore, in contrast to what has been described in other pseudostratified epithelia such as neuroepithelium, the majority of cells dividing apically detached completely from the basal pole in the epiblast.Cell rearrangement associated with mitotic cell rounding in the posterior epiblast during gastrulation, in particular when it occurs on the basal side, might thus facilitate cell ingression through the PS and transition to a mesenchymal phenotype.GRAPHICAL ABSTRACT

scholarly journals A TgfβRI/Snai1-dependent developmental module at the core of vertebrate axial elongation

2020 ◽  
Author(s):  
André Dias ◽  
Anastasiia Lozovska ◽  
Filip J. Wymeersch ◽  
Ana Nóvoa ◽  
Anahi Binagui-Casas ◽  
...  
Keyword(s):  
Epithelial To Mesenchymal Transition ◽  
Primitive Streak ◽  
Body Axis ◽  
Tail Bud ◽  
Mesenchymal Transition ◽  
Axial Elongation ◽  
The Core ◽  
Primary Body ◽  
Transitory State

ABSTRACTFormation of the vertebrate postcranial body axis follows two sequential but distinct phases. The first phase generates pre-sacral structures (the so-called primary body) through the activity of the primitive streak (PS) on axial progenitors within the epiblast. The embryo then switches to generate the secondary body (post-sacral structures), which depends on axial progenitors in the tail bud. Here we show that the mammalian tail bud is generated through an independent developmental module, concurrent but functionally different to that generating the primary body. This module is triggered by convergent TgfβRI and Snai1 activities that promote an incomplete epithelial to mesenchymal transition (EMT) on a subset of epiblast axial progenitors. This EMT is functionally different to that coordinated by the PS, as it does not lead to mesodermal differentiation but brings axial progenitors into a transitory state, keeping their progenitor activity to drive further axial body extension.

scholarly journals Local cell interactions and self-amplifying individual cell ingression drive amniote gastrulation

eLife ◽  
2014 ◽  
Vol 3 ◽  
Author(s):  
Octavian Voiculescu ◽  
Lawrence Bodenstein ◽  
I-Jun Lau ◽  
Claudio D Stern
Keyword(s):  
Large Scale ◽  
Epithelial To Mesenchymal Transition ◽  
Primitive Streak ◽  
Cell Interactions ◽  
Mesenchymal Transition ◽  
Deep Layers ◽  
Single Sheet ◽  
Epithelial Sheet ◽  
Local Cell ◽  
Cell Intercalation

Gastrulation generates three layers of cells (ectoderm, mesoderm, endoderm) from a single sheet, while large scale cell movements occur across the entire embryo. In amniote (reptiles, birds, mammals) embryos, the deep layers arise by epithelial-to-mesenchymal transition (EMT) at a morphologically stable midline structure, the primitive streak (PS). We know very little about how these events are controlled or how the PS is maintained despite its continuously changing cellular composition. Using the chick, we show that isolated EMT events and ingression of individual cells start well before gastrulation. A Nodal-dependent ‘community effect’ then concentrates and amplifies EMT by positive feedback to form the PS as a zone of massive cell ingression. Computer simulations show that a combination of local cell interactions (EMT and cell intercalation) is sufficient to explain PS formation and the associated complex movements globally across a large epithelial sheet, without the need to invoke long-range signalling.

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