Induction And Migration Of Cranial Neural Crest Cells
Neural Crest Cells are specific for vertebrate animals. They develop at the border between neural plate and ectoderm. Cranial Neural Crest (CNC) cells are a good model for investigating migratory behaviour of cells which is an important process during development and tumour metastasis.
We focus on the induction and the regulation of migration of CNC cells and the involvement of cell adhesion in this process. The cell-cell adhesion molecules of Cadherins are mostly down-regulated with onset of CNC migration, thus leading to a reduction of cell-cell adhesion and the ability to migrate, but a classical type II- cadherin, Cadherin-11, instead is up-regulated (Fig. 1a). Cadherins form a super gene family of calcium dependent transmembrane proteins serving as cell adhesion molecules via homophilic binding sites. Classic cadherins, as one type of earliest found and more important ones consist of five extracellular repeats (EC1-5). Classic type I cadherins are characterized by the presence of conserved sequence motifs, such as HAV tripeptide which is most probably directly involved in the homopholic interaction, whereas this kind of tripeptide is replaced by a QAV or QAI motif in type II cadherins (Fig. 1b).
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Fig. 1A: Xcadherin-11 is expressed in the migrating cranial neural crest cells. Fig. 1B: Structure of Xcadherin-11: The protein consists of 5 extracellular domains that are involved in homophilic binding of cadherins of the same type. The cytoplasmic tail has binding sides for -catenin and p120 that can be involved in intracellular signalling events. |
Although the characterization of type I cadherins have been well known in a number of species, much less data are reported for the type II cadherins. Cadherin-11 (OB-Cadherin), as the most prominent cadherin was first detected in mesenchymal tissues in mouse and human, and is involved in osteoblast formation. The Xenopus homologue of cadherin-11 (Xcad-11) was isolated in our group and found to be involved in neural crest (NC) cell migration.
During overexpression studies of the oncogene c-myc, which is one of the earliest inducers for neural crest, we found an induction of Xcadherin-11 (Fig.2).
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Fig 2: Overespression of c-myc induces an enhanced formation of Xcadherin-11 positive cells. A: injected side, B: dorsal view, C: not injected side, D: horizontal section through the head region. The asterix marks the injected side. |
We have shown earlier that overexpression of Cadherin-11 leads to a reduced migration of CNC cells. Deletion mutants indicate that the cytoplasmic tail of Cadherin-11 is responsible for this action, possibly via capturing cytosolic β-catenin, since this molecule is able to rescue the phenotype. Knock-down of Cadherin-11 with Morpholino oligonucleotides leads to gastrulation defects as well as to reduced migration of CNC cells (Fig. 3) and an increase in dorsally located cells.
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Fig. 3: A reduction of Xcadherin-11 protein by use of morpholino oligonucleotides results in the loss of migration of cranial neural crest cells as seen by in situ hybridization for the CNC marker gene twist.. Mainly the hyoidal and branchial arches are affected. A: not injected side, B: dorsal view, C: injected side. The asterix marks the injected side. |
To further examine this phenotype we perform transplantation assays that offer the possibility to study in vivo cell migration of CNC cells in Xenopus embryos. A donor is labelled with a fluorescent dye and the CNC cells are then transplanted into an unlabelled host. The migrating cells can then be followed by microscopy (Fig. 4).
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Fig. 4: Scheme of transplantation assay for in vivo imaging of CNC migration. Labelled donor cells are transplanted to an unlabelled host. For further characterization between the different arches cells can be used from differently labelled donors. |
Publications
- Koehler A., Schlupf J., Schneider M., Kraft B., Winter C., Kashef J. (2013)
Loss of Xenopus cadherin-11 leads to increased Wnt/β-catenin signaling and up-regulation of target genes c-myc and cyclin D1 in neural crest
Original Research Article Dev. Biol. 2013, In Press http://dx.doi.org/10.1016/j.ydbio.2013.08.007 - Alexander Körner, Christina Deichmann, Fernanda F. Rossetti, Almut Köhler, Oleg V. Konovalov, Doris Wedlich, Motomu Tanaka.
Cell Differentiation of Pluripotent Tissue Sheets Immobilized on Supported Membranes Displaying Cadherin-11. PLoS ONE02/2013; 8(2):e54749 - Jubin Kashef, Almut Köhler, Sei Kuriyama, Dominique Alfandari, Roberto Mayor, and Doris Wedlich. Cadherin-11 regulates protrusive activity in Xenopus cranial neural crest cells upstream of Trio and the small GTPases. Genes Dev. 2009; 23: 1393-1398
- Jubin Kashef, Almut Köhler, Doris Wedlich. Die Routenplaner der Neuralleistenzellen. Biospektrum, 2007, 3, 242- 245
- Almut Köhler, Alexandra Schambony and Doris Wedlich. Cell migration under control of Wnt-signaling in the vertebrate embryo. In: S. Sokol, ed. Wnt Signaling in Embryonic Development. Advances in Developmental Biology, 2007, 17, 159-202
- Ruan G, Wedlich D, Koehler A. Xenopus cadherin-6 regulates growth and epithelial development of the retina. Mech Dev. 2006; 123(12):881-892
- Koebernick K, Kashef J, Pieler T, Wedlich D. Xenopus Teashirt1 regulates posterior identity in brain and cranial neural crest. Dev Biol. 2006;298(1):312-26
- Gui Ruan, Doris Wedlich, and Almut Kohler. How Cell-Cell Adhesion Contributes to Early Embryonic Development. In: H. Grunz, ed. The Vertebrate Organizer. Berlin: Springer, 2004;201-218
- Grossmann R, Jurkevich A, Kohler A. Sex dimorphism in the avian arginine vasotocin system with special emphasis to the bed nucleus of the stria terminalis. Comp Biochem Physiol A Mol Integr Physiol. 2002; 131(4):833-783
- Jurkevich A, Barth SW, Kuenzel WJ, Kohler A, Grossmann R. Development of sexually dimorphic vasotocinergic system in the bed nucleus of stria terminalis in chickens.J Comp Neurol. 1999; 408(1):46-60
The people
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Dr. Almut Köhler
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and formerly Christine van Lishout
