Drosophila dorsal closure: An orchestra of forces to zip shut the embryo

- Dorsal closure is a tissue fusion event involving several force generating and tissue remodeling mechanisms.
- Tissue contraction, supracellular actin cable formation and protrusion mediated epithelial zipping drive dorsal closure.
- Acto---myosin machinery, adhesion and apoptosis act as key mechanical players in the process.
- Biophysical models have been developed to describe the interplay between the different forces and single cell behavior.

Dorsal closure, a late-embryogenesis process, consists in the sealing of an epidermal gap on the dorsal side of the Drosophila embryo. Because of its similarities with wound healing and neural tube closure in humans, it has been extensively studied in the last twenty years. The process requires the coordination of several force generating mechanisms, that together will zip shut the epidermis. Recent works have provided a precise description of the cellular behavior at the origin of these forces and proposed quantitative models of the process. In this review, we will describe the different forces acting in dorsal closure. We will present our current knowledge on the mechanisms generating and regulating these forces and report on the different quantitative mathematical models proposed so far.