scholarly journals A biphasic role of non-canonical Wnt16 signaling during early anterior-posterior patterning and morphogenesis of the sea urchin embryo

Development ◽  
2019 ◽  
Vol 146 (24) ◽  
pp. dev168799 ◽  
Author(s):  
Marina Martínez-Bartolomé ◽  
Ryan C. Range
Keyword(s):  
Sea Urchin ◽  
Sea Urchin Embryo ◽  
Anterior Posterior

Autonomous and non-autonomous differentiation of ectoderm in different sea urchin species

Development ◽  
1995 ◽  
Vol 121 (5) ◽  
pp. 1497-1505 ◽  
Author(s):  
A.H. Wikramanayake ◽  
B.P. Brandhorst ◽  
W.H. Klein
Keyword(s):  
Sea Urchin ◽  
Strongylocentrotus Purpuratus ◽  
Protein A ◽  
Cellular Interactions ◽  
V Protein ◽  
Lytechinus Pictus ◽  
Sea Urchin Embryo ◽  
Oral Ectoderm ◽  
Temporal And Spatial

During early embryogenesis, the highly regulative sea urchin embryo relies extensively on cell-cell interactions for cellular specification. Here, the role of cellular interactions in the temporal and spatial expression of markers for oral and aboral ectoderm in Strongylocentrotus purpuratus and Lytechinus pictus was investigated. When pairs of mesomeres or animal caps, which are fated to give rise to ectoderm, were isolated and cultured they developed into ciliated embryoids that were morphologically polarized. In animal explants from S. purpuratus, the aboral ectoderm-specific Spec1 gene was activated at the same time as in control embryos and at relatively high levels. The Spec1 protein was restricted to the squamous epithelial cells in the embryoids suggesting that an oral-aboral axis formed and aboral ectoderm differentiation occurred correctly. However, the Ecto V protein, a marker for oral ectoderm differentiation, was detected throughout the embryoid and no stomodeum or ciliary band formed. These results indicated that animal explants from S. purpuratus were autonomous in their ability to form an oral-aboral axis and to differentiate aboral ectoderm, but other aspects of ectoderm differentiation require interaction with vegetal blastomeres. In contrast to S. purpuratus, aboral ectoderm-specific genes were not expressed in animal explants from L. pictus even though the resulting embryoids were morphologically very similar to those of S. purpuratus. Recombination of the explants with vegetal blastomeres or exposure to the vegetalizing agent LiCl restored activity of aboral ectoderm-specific genes, suggesting the requirement of a vegetal induction for differentiation of aboral ectoderm cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Specification of endoderm and mesoderm in the sea urchin

Zygote ◽  
1999 ◽  
Vol 8 (S1) ◽  
pp. S41-S41 ◽  
Author(s):  
David R. McClay
Keyword(s):  
Sea Urchin ◽  
Wnt Pathway ◽  
Special Significance ◽  
Nuclear Entry ◽  
Cell Stage ◽  
Animal Pole ◽  
Secondary Axis ◽  
Sea Urchin Embryo ◽  
Vegetal Pole

It has long been recognized that micromeres have special significance in early specification events in the sea urchin embryo. Micromeres have the ability to induce a secondary axis if transferred to the animal pole at the 16-cell stage of sea urchin embryos (Hörstadius, 1939). Without micromeres an isolated animal hemisphere develops into an ectodermal ball called a dauer blastula. Addition of micromeres to an animal half rescues a normal pluteus larva, including endoderm (Hörstadius, 1939). Despite these well-known experiments, however, neither the molecular basis of that induction nor the endogenous inductive role of micromeres in development was known. In recent experiments we learned that if one eliminates micromeres from the vegetal pole at the 16-cell stage the resulting embryo makes no secondary mesenchyme. Earlier it had been found that β-catenin is crucial for specification events that lead to mesoderm and endoderm (Wikra-manayake et al., 1998; Emily-Fenouil et al., 1998; Logan et al., 1999). We noticed that at the 16-cell stage β-catenin enters the nuclei of micromeres, then enters the nuclei of macromeres at the 32-cell stage (Logan et al., 1999). Since nuclear entry of β-catenin is known to be important for its signalling function in the Wnt pathway, we asked whether β-catenin functions in the micromere induction pathway.

Lim1-related homeobox gene (HpLim1) expressed in sea urchin embryo

Zygote ◽  
1999 ◽  
Vol 8 (S1) ◽  
pp. S71-S72
Author(s):  
Keiko Mitsunaga-Nakatsubo ◽  
Takahiko Kawasaki ◽  
Koichi Takeda ◽  
Koji Akasaka ◽  
Hiraku Shimada
Keyword(s):  
Sea Urchin ◽  
Expression Patterns ◽  
Homeobox Gene ◽  
Mesoderm Induction ◽  
Over Expression ◽  
Lim Domains ◽  
Sea Urchin Embryo ◽  
Cell Type Specific ◽  
Islet 1

A characteristic cysteine-rich motif, LIM domain, was first detected in three different transcription factors: lin-11, Islet-1 and mec-3. A feature shared by these genes is the presence of two LIM domains linked to a DNA-binding homeodomain (Sánchez-García et al., 1994). LIM homeodomain (LHX) proteins have been reported to be implicated in a variety of developmental processes (Dawid et al., 1998).Expression patterns of LHX genes have been analysed in a wide variety of organisms and reported to be cell-type specific (Dawid et al., 1998). In vertebrates, they are expressed in organiser equivalent regions at the gastrula stage, suggesting their involvement in mesoderm induction (Taira et al., 1992; Barnes et al., 1994; Toyama et al., 1995). Hrlim, an ascidian Lim3, zygotically expresses in the endoderm lineage before gastrulation, suggesting that it is involved in the endoderm determination (Wada et al., 1995).Here, cDNA cloning of the Lim1-related homeobox gene (HpLim1) of the sea urchin, Hemicentrotus pulcherrimus, is described together with the spatially as well as temporally regulated expression of HpLim1 during sea urchin development. A possible role of HpLiml in sea urchin development is also discussed based on its spatial pattern of expression and on the result of an over-expression study.

scholarly journals A dual role for Axin in establishing the anterior-posterior axis in the early sea urchin embryo

2020 ◽  
Author(s):  
Hongyan Sun ◽  
ChiehFu Jeff Peng ◽  
Lingyu Wang ◽  
Honglin Feng ◽  
Athula H. Wikramanayake
Keyword(s):  
Gene Expression ◽  
Sea Urchin ◽  
Glycogen Synthase ◽  
Negative Regulator ◽  
Cell Surface Receptor ◽  
Ligand Complex ◽  
Sea Urchin Embryo ◽  
Early Embryos ◽  
Gsk 3Β ◽  
Anterior Posterior

AbstractThe activation of Wnt/β-catenin (cWnt) signaling at the future posterior end of early embryos is a highly conserved mechanism for initiating pattern formation along the anterior-posterior (AP) axis in bilaterians. Moreover, in many bilaterian taxa, in addition, to activation of cWnt signaling at the posterior end, inhibition of cWnt signaling at the anterior end is required for normal development of anterior structures. In most cases, inhibition of cWnt signaling at the anterior end occurs around gastrulation and it is typically mediated by secreted factors that block signal transduction through the cWnt cell surface receptor-ligand complex. This phenomenon has been fairly well characterized, but the emerging role for intracellular inhibition of cWnt signaling in future anterior blastomeres—in cleavage stage embryos—to regulate correct AP patterning is less well understood. To investigate this process in an invertebrate deuterostome embryo we studied the function of Axin, a critical negative regulator of cWnt signaling, during early sea urchin embryogenesis. Sea urchin Axin is ubiquitously expressed in early embryos and by the blastula stage the expression of the gene becomes restricted to the posterior end of the embryo. Strikingly, knockdown of Axin protein levels using antisense Axin morpholinos (MO) led to ectopic nuclearization of β-catenin and activation of endomesoderm gene expression in anterior blastomeres in early embryos. These embryos developed a severely posteriorized phenotype that could be fully rescued by co-injection of Axin MO with wild-type Axin mRNA. Axin is known to negatively regulate cWnt by its role in mediating β-catenin stability within the destruction complex. Consistent with this function overexpression of Axin by mRNA injection led to the downregulation of nuclear β-catenin, inhibition of endomesoderm specification and a strong anteriorization of embryos. Axin has several well-defined domains that regulate its interaction with β-catenin and the key regulators of the destruction complex, Adenomatous Polyposis Coli (APC), Glycogen Synthase Kinase 3β(GSK-3β), and Dishevelled (Dvl). Using Axin constructs with single deletions of the binding sites for these proteins we showed that only the GSK-3βbinding site on Axin is required for its inhibition of cWnt in the sea urchin embryo. Strikingly, overexpression of the GSK-3β-binding domain alone led to embryos with elevated levels of endomesoderm gene expression and a strongly posteriorized phenotype. These results indicated that Axin has a critical global role in inhibiting cWnt signaling in the early sea urchin embryo, and moreover, that the interaction of Axin with GSK-3βis critical for this inhibition. These results also add to the growing body of evidence that Axin plays a global function in suppressing cWnt signaling in early embryos and indicates that modulation of Axin function may be a critical early step during patterning of the AP axis during bilaterian development

scholarly journals A precise regulation of presenilin expression is required for the sea urchin early development

2021 ◽  
Author(s):  
Odile Bronchain ◽  
Laetitia Philippe-Caraty ◽  
Vincent Anquetil ◽  
Brigitte Ciapa
Keyword(s):  
Sea Urchin ◽  
Crucial Role ◽  
Senile Plaques ◽  
Ciliated Cells ◽  
Cellular Functions ◽  
Aβ Peptides ◽  
Multiple Substrates ◽  
Sea Urchin Embryo ◽  
Secretase Activity

Presenilins or PSENs homologues are widely expressed across eukaryotes. Two PSEN are expressed in humans where they play a crucial role in Alzheimer's disease (AD). Each PSEN can be part of the γ-secretase complex that has multiple substrates such as Notch or the amyloid precursor protein (AβPP) which gives the Aβ peptides composing the senile plaques during AD. PSENs also interact with various proteins independently of their γ-secretase activity. They can then be involved in numerous cellular functions, which makes their role in a given cell and/or organism complex to decipher. We settled the sea urchin embryo as a new model to study the role of PSEN. PSEN is present in unduplicated form and highly similar to that of humans. Our results suggest that its expression must be precisely tuned to control the course of the first mitotic cycles and the associated Cai transients, gastrulation execution and, probably in association with ciliated cells, the establishment of the pluteus. We suggest that it would be relevant to study the role of PSEN within the GRN deciphered in the sea urchin.

The role of sea urchin embryo BMP-1 in skeleton assembly

1996 ◽  
Vol 15 (3) ◽  
pp. 150 ◽  
Author(s):  
L.G. Huggins ◽  
S-P. Hwang ◽  
W.J. Lennarz
Keyword(s):  
Sea Urchin ◽  
Sea Urchin Embryo

scholarly journals Role of serotonin in sea urchin embryo morphogenesis

2008 ◽  
Vol 319 (2) ◽  
pp. 520
Author(s):  
Kamali N. Carroll ◽  
Tara A. Scully ◽  
Erin S. Mateer ◽  
Ying Cheng ◽  
Meliha Dzirlo-Ayvaz ◽  
...  
Keyword(s):  
Sea Urchin ◽  
Sea Urchin Embryo

scholarly journals An early global role for Axin is required for correct patterning of the anterior-posterior axis in the sea urchin embryo

Development ◽  
2021 ◽  
pp. dev.191197
Author(s):  
Hongyan Sun ◽  
ChiehFu Jeff Peng ◽  
Lingyu Wang ◽  
Honglin Feng ◽  
Athula H. Wikramanayake
Keyword(s):  
Functional Analysis ◽  
Sea Urchin ◽  
Function Analysis ◽  
Cleavage Stage ◽  
Cell Fates ◽  
Sea Urchin Embryo ◽  
Early Embryos ◽  
Gsk 3Β ◽  
Intracellular Inhibition ◽  
Anterior Posterior

Activation of Wnt/β-catenin (cWnt) signaling at the future posterior end of early bilaterian embryos is a highly conserved mechanism for establishing the anterior-posterior (AP) axis. Moreover, inhibition of cWnt at the anterior end is required for development of anterior structures in many deuterostome taxa. This phenomenon, which occurs around the time of gastrulation, has been fairly well characterized but the significance of intracellular inhibition of cWnt signaling in cleavage-stage deuterostome embryos for normal AP patterning is less well understood. To investigate this process in an invertebrate deuterostome we defined Axin function in early sea urchin embryos. Axin is ubiquitously expressed at relatively high levels in early embryos and functional analysis revealed that Axin suppresses posterior cell fates in anterior blastomeres by blocking ectopic cWnt activation in these cells. Structure-function analysis of sea urchin Axin demonstrated that only its GSK-3β-binding domain is required for cWnt inhibition. These observations and results in other deuterostomes suggest that Axin plays a critical conserved role in embryonic AP patterning by preventing cWnt activation in multipotent early blastomeres, thus protecting them from assuming ectopic cell fates.

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