Embryos repair epithelial wounds rapidly in a process driven by collective cell movements. Upon wounding, actin and the molecular motor non-muscle myosin II are redistributed in the cells adjacent to the wound, forming a supracellular purse string around the lesion. Purse string contraction coordinates cell movements and drives rapid wound closure. By using fluorescence recovery after photobleaching in Drosophila embryos, we found that myosin turns over as the purse string contracts. Myosin turnover at the purse string was slower than in other actomyosin networks that had a lower level of contractility. Mathematical modelling suggested that myosin assembly and disassembly rates were both reduced by tension at the wound edge. We used laser ablation to show that tension at the purse string increased as wound closure progressed, and that the increase in tension was associated with reduced myosin turnover. Reducing purse string tension by laser-mediated severing resulted in increased turnover and loss of myosin. Finally, myosin motor activity was necessary for its stabilization around the wound and for rapid wound closure. Our results indicate that mechanical forces regulate myosin dynamics during embryonic wound repair.
The authors declare no competing or financial interests.
A.B.K. and R.F.-G. conceived the study, designed the experiments, analysed the results and wrote the manuscript. A.B.K. and T.Z.-C. conducted the experiments.
This research was supported by the Ontario Ministry of Economic Development and Innovation (ER14-10-170 to R.F.-G., and Trillium Scholarship to T.Z.-C.), the Natural Sciences and Engineering Research Council of Canada (418438-13), the Canada Foundation for Innovation (30279), the Delta Kappa Gamma Society International (World Fellowship to T.Z.-C.), and University of Toronto, Institute of Biomaterials and Biomedical Engineering Wildcat and International Scholarships (to A.B.K.).
Supplementary information available online at http://jcs.biologists.org/lookup/doi/10.1242/jcs.196139.supplemental
- Received August 4, 2016.
- Accepted January 3, 2017.
- © 2017. Published by The Company of Biologists Ltd