Myosin II Dynamics Are Regulated by Tension in Intercalating Cells

Abstract

Summary Axis elongation in Drosophila occurs through polarized cell rearrangements driven by actomyosin contractility. Myosin II promotes neighbor exchange through the contraction of single cell boundaries, while the contraction of myosin II structures spanning multiple pairs of cells leads to rosette formation. Here we show that actomyosin cables form at a higher frequency than expected by chance during elongation, indicating that cable assembly is an active process. Multicellular cables are sites of increased mechanical tension as measured by laser ablation. Fluorescence recovery after photobleaching experiments show that myosin II is stabilized at the cortex in regions of increased tension. Myosin II is recruited in response to an ectopic force and relieving tension leads to a rapid loss of myosin, indicating that tension is necessary and sufficient for cortical myosin localization. These results demonstrate that myosin II dynamics are regulated by tension in a positive feedback loop that leads to actomyosin cable formation and efficient tissue elongation.

Mitotic cell rounding and epithelial thinning regulate lumen growth and shape

“…5b,b 0 ,b 00 ; Supplementary Movie 8). We then estimated the initial recoil velocity of the F-actin cortex as a quantitative estimate of tension in the network [28][29][30] . The recoil velocity in the rounding cells was higher than that in the interphase cells (Fig.…”

Tissue Stiffness Dictates Development, Homeostasis, and Disease Progression

“…24 Tight junctions and adherens junctions mediate the forces exerted between cells to compartmentalize these developing tissues. Additionally, myosin II is enriched at sites of tension application on the surface of intercalating cells, 26 suggesting that anisotropy in the micromechanical environment contributes significantly to pattern formation. Later during gastrulation, tissue folding is initiated by a subset of cells that physically constrict their apical membranes and expand their basal domains along the ventral midline of the embryo, resulting in tissue invagination.…”

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