Inhibition of FGF signaling converts dorsal mesoderm to ventral mesoderm in early Xenopus embryos

2011 ◽  
Vol 82 (2) ◽  
pp. 99-107 ◽  
Author(s):  
Sung-Young Lee ◽  
Soo-Kyung Lim ◽  
Sang-Wook Cha ◽  
Jaeho Yoon ◽  
Seung-Hwan Lee ◽  
...  
Keyword(s):  
Fgf Signaling ◽  
Xenopus Embryos ◽  
Dorsal Mesoderm

The origins of primitive blood in Xenopus: implications for axial patterning

Development ◽  
1999 ◽  
Vol 126 (3) ◽  
pp. 423-434 ◽  
Author(s):  
M.C. Lane ◽  
W.C. Smith
Keyword(s):  
Xenopus Laevis ◽  
Marginal Zone ◽  
Cell Stage ◽  
Axial Patterning ◽  
Xenopus Embryos ◽  
Spemann's Organizer ◽  
Dorsal Mesoderm

The marginal zone in Xenopus laevis is proposed to be patterned with dorsal mesoderm situated near the upper blastoporal lip and ventral mesoderm near the lower blastoporal lip. We determined the origins of the ventralmost mesoderm, primitive blood, and show it arises from all vegetal blastomeres at the 32-cell stage, including blastomere C1, a progenitor of Spemann's organizer. This demonstrates that cells located at the upper blastoporal lip become ventral mesoderm, not solely dorsal mesoderm as previously believed. Reassessment of extant fate maps shows dorsal mesoderm and dorsal endoderm descend from the animal region of the marginal zone, whereas ventral mesoderm descends from the vegetal region of the marginal zone, and ventral endoderm descends from cells located vegetal of the bottle cells. Thus, the orientation of the dorsal-ventral axis of the mesoderm and endoderm is rotated 90(degrees) from its current portrayal in fate maps. This reassessment leads us to propose revisions in the nomenclature of the marginal zone and the orientation of the axes in pre-gastrula Xenopus embryos.

scholarly journals Ectopic EphA4 Receptor Induces Posterior Protrusions via FGF Signaling in Xenopus Embryos

2004 ◽  
Vol 15 (4) ◽  
pp. 1647-1655 ◽  
Author(s):  
Eui Kyun Park ◽  
Neil Warner ◽  
Yong-Sik Bong ◽  
David Stapleton ◽  
Ryu Maeda ◽  
...  
Keyword(s):  
Tyrosine Kinases ◽  
Sh2 Domain ◽  
Binding Motif ◽  
Eph Receptors ◽  
Fgf Signaling ◽  
Wild Type ◽  
Sam Domain ◽  
Xenopus Embryos

The Eph family of receptor tyrosine kinases regulates numerous biological processes. To examine the biochemical and developmental contributions of specific structural motifs within Eph receptors, wild-type or mutant forms of the EphA4 receptor were ectopically expressed in developing Xenopus embryos. Wild-type EphA4 and a mutant lacking both the SAM domain and PDZ binding motif were constitutively tyrosine phosphorylated in vivo and catalytically active in vitro. EphA4 induced loss of cell adhesion, ventro-lateral protrusions, and severely expanded posterior structures in Xenopus embryos. Moreover, mutation of a conserved SAM domain tyrosine to phenylalanine (Y928F) enhanced the ability of EphA4 to induce these phenotypes, suggesting that the SAM domain may negatively regulate some aspects of EphA4 activity in Xenopus. Analysis of double mutants revealed that the Y928F EphA4 phenotypes were dependent on kinase activity; juxtamembrane sites of tyrosine phosphorylation and SH2 domain-binding were required for cell dissociation, but not for posterior protrusions. The induction of protrusions and expansion of posterior structures is similar to phenotypic effects observed in Xenopus embryos expressing activated FGFR1. Furthermore, the budding ectopic protrusions induced by EphA4 express FGF-8, FGFR1, and FGFR4a. In addition, antisense morpholino oligonucleotide-mediated loss of FGF-8 expression in vivo substantially reduced the phenotypic effects in EphA4Y928F expressing embryos, suggesting a connection between Eph and FGF signaling.

scholarly journals Kindlin2 regulates neural crest specification via integrin-independent regulation of the FGF signaling pathway

Development ◽  
2021 ◽  
Author(s):  
Hui Wang ◽  
Chengdong Wang ◽  
Qi Long ◽  
Yuan Zhang ◽  
Meiling Wang ◽  
...  
Keyword(s):  
Neural Crest ◽  
Signaling Pathway ◽  
Fgf Signaling ◽  
Loss Of Function ◽  
Integrin Activation ◽  
Fgf Receptor ◽  
Adhesion Protein ◽  
Xenopus Embryos ◽  
Focal Adhesion Protein ◽  
The Stability

The focal adhesion protein Kindlin2 is essential for integrin activation, a process that is fundamental to cell-extracellular matrix adhesion. Kindlin2 is widely expressed in mouse embryos, and its absence causes lethality at the peri-implantation stage due to the failure to trigger integrin activation. The function of kindlin2 during embryogenesis has not yet been fully elucidated as a result of this early embryonic lethality. Here, we showed that kindlin2 is essential for neural crest (NC) formation in Xenopus embryos. Loss-of-function assays performed with kindlin2-specific morpholino antisense oligos (MOs) or clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 techniques in Xenopus embryos severely inhibit the specification of NC. Moreover, integrin-binding deficient mutants of Kindlin2 rescued the phenotype caused by loss of kindlin2, suggesting that the function of kindlin2 during NC specification is independent of integrins. Mechanistically, we found that Kindlin2 regulates the fibroblast growth factor (FGF) pathway, and promotes the stability of FGF receptor 1. Our study reveals a novel function of Kindlin2 in regulating FGF signaling pathway and provides mechanistic insights into the function of Kindlin2 during NC specification.

Mutant Vg1 ligands disrupt endoderm and mesoderm formation in Xenopus embryos

Development ◽  
1998 ◽  
Vol 125 (14) ◽  
pp. 2677-2685 ◽  
Author(s):  
E.M. Joseph ◽  
D.A. Melton
Keyword(s):  
Gene Function ◽  
Ectopic Expression ◽  
Embryonic Cells ◽  
Xenopus Embryos ◽  
Maternal Mrna ◽  
Dorsal Mesoderm ◽  
Mesoderm Formation

The Xenopus Vg1 gene, a TGFbeta superfamily member, is expressed as a maternal mRNA localized to prospective endoderm, and mature Vg1 protein can induce both endodermal and mesodermal markers in embryonic cells. Most previous work on embryonic inducers, including activin, BMPs and Vg1, has relied on ectopic expression to assay for gene function. Here we employ a mutant ligand approach to block Vg1 signaling in developing embryos. The results indicate that Vg1 expression is essential for normal endodermal development and the induction of dorsal mesoderm in vivo.

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