Tension regulates myosin dynamics during Drosophila embryonic wound repair

Abstract

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.

Regionalized tissue fluidization is required for epithelial gap closure during insect gastrulation

“…The order in which cells are evicted correlates with local myosin accumulation at each cable-forming edge. This is consistent with previous findings that myosin intensity correlates with tension in wound-healing cables 36 , 37 . Furthermore, it has been suggested that a non-uniform stepwise contractility of individual edges is necessary for efficient epithelial closure during wound healing in Drosophila embryos and neural tube closure in chordates 38 , 39 .…”

Tensile forces drive a reversible fibroblast-to-myofibroblast transition during tissue growth in engineered clefts

“…1 ), and the same effect can be induced by decreasing the cleft angle ( 18 ). This interpretation is in agreement with in vivo data because cytoskeletal tension was reported to up-regulate myosin dynamics during Drosophila embryonic wound repair ( 4 ), whereby myosin activity is regulated by RhoA/Rock. Also in agreement with the data, we found previously that FN fiber tension in early ECM is up-regulated in a RhoA-dependent manner ( 25 ).…”

Dissipation of contractile forces: the missing piece in cell mechanics

“…, 2011; Tojkander et al. , 2015), or from the turnover of myosin, which is reduced as tension increases (Kobb et al. , 2017).…”