Gastrulation leads to the formation of the embryonic germ layers, ectoderm, mesoderm and endoderm, and is the first key morphogenetic process that occurs in development. Gastrulation provides a unique developmental assay system in which to study cellular movements and rearrangements in vivo.
The different cell movements occurring during gastrulation take place in a highly coordinated spatial and temporal manner, indicating that they must be controlled by a complex interplay of morphogenetic and inductive events. Generally, cell movement constitutes a highly integrated program of different cellular behaviors including sensing, polarization, cytoskeletal reorganization, and changes in adhesion and cell shape. During migration, these different behaviors require a continuous regulation and feedback control to direct and coordinate them.
In this work, we analyze the cellular and molecular mechanisms underlying the different types of cell behaviors during gastrulation in zebrafish. Specifically, we focus on the role of the adhesive and mechanical properties of germ layer progenitors in the regulation of gastrulation movements. In the first part of the project, we investigated the role of the adhesive and mechanical properties of the different germ layer progenitor cell types for germ layer separation and stratification. In the second part of this study, we applied the same methodology to determine the function of germ layer progenitor cell adhesion in collective cell migration.
Tissue organization is thought to depend on the adhesive and mechanical properties of the constituent cells. However, it has been difficult to determine the precise contribution of these different properties due to the lack of tools to measure them. Here we use atomic force microscopy (AFM) to quantify the adhesive and mechanical properties of the different germ layer progenitor cell types. Applying this methodology, we demonstrate that mesoderm and endoderm progenitors are more adhesive than ectoderm cells and that E-cadherin is the main adhesion molecule regulating this differential adhesion. In contrast, ectoderm progenitors exhibit a higher actomyosin-dependent cell cortex tension than mesoderm and endoderm progenitors. Combining these data with tissue self-assembly in vitro and in vivo, we provide evidence that the combinatorial activities of cell adhesion and cell cortex tension direct germ layer separation and stratification.
It has been hypothesized that the directionality of cell movement during collective migration results from a collective property. Using a single cell transplantation assay, we show that individual progenitor cells are capable of normal directed migration when moving as single cells, but require cell-cell adhesion to participate in coordinated and directed migration when moving collectively.
These findings contribute to the understanding of the gastrulation process. Cell-cell adhesion is required for collective germ layer progenitor cell migration, and cell cortex tension is critical for germ layer separation and stratification. However, many questions still have to be solved. Future studies will have to explore the interaction between the adhesive and mechanical progenitor cell properties, as well as the role of these properties for cell protrusion formation, cell polarization, interaction with extracellular matrix, and their regulation by different signaling pathways.
| Identifer | oai:union.ndltd.org:DRESDEN/oai:qucosa:de:qucosa:25271 |
| Date | 25 March 2010 |
| Creators | Arboleda-Estudillo, Yoana |
| Contributors | Heisenberg, Carl-Philipp, Müller, Daniel, Navascués-Martinez, Julio, Technische Universität Dresden |
| Publisher | Max-Planck-Institut für Molekulare Zellbiologie und Genetik |
| Source Sets | Hochschulschriftenserver (HSSS) der SLUB Dresden |
| Language | English |
| Detected Language | English |
| Type | doc-type:doctoralThesis, info:eu-repo/semantics/doctoralThesis, doc-type:Text |
| Rights | info:eu-repo/semantics/openAccess |
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