Models of convergent extension during morphogenesis

5 years ago

Models of convergent extension during morphogenesis

Asako Shindo

Convergent extension (CE) is a fundamental and conserved collective cell movement that forms elongated tissues during embryonic development. Thus far, studies have demonstrated two different mechanistic models of collective cell movements during CE. The first, termed the crawling mode, was discovered in the process of notochord formation in Xenopus laevis embryos, and has been the established model of CE for decades. The second model, known as the contraction mode, was originally reported in studies of germband extension in Drosophila melanogaster embryos and was recently demonstrated to be a conserved mechanism of CE among tissues and stages of development across species. This review summarizes the two modes of CE by focusing on the differences in cytoskeletal behaviors and relative expression of cell adhesion molecules. The upstream molecules regulating these machineries are also discussed. There are abundant studies of notochord formation in X. laevis embryos, as this was one of the pioneering model systems in this field. Therefore, the present review discusses these findings as an approach to the fundamental biological question of collective cell regulation. For further resources related to this article, please visit the WIREs website. This review discusses two modes of convergent extension (CE), the crawling and the contraction modes, and summarizes cell movements elicited by cytoskeleton dynamics, the participation of cell adhesion molecules, and the involvement of upstream regulatory molecules for each mode. Notochord formation in Xenopus laevis embryos has been one of the pioneering model systems of CE, thus the findings from the studies of X. laevis are mainly focused to approach the biological question of collective cell movement.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1002/wdev.293