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The cell cortex plays many critical roles, including interpreting and responding to internal and external signals. One behavior which supports a cell’s ability to respond to both internal and externally-derived signaling is cortical excitability, wherein coupled positive and negative feedback loops generate waves of actin polymerization and depolymerization at the cortex. Cortical excitability is a highly conserved behavior, having been demonstrated in many cell types and organisms. One system well-suited to studying cortical excitability isXenopus laevis, in which cortical excitability is easily monitored for many hours after fertilization. Indeed, recent investigations usingX. laevishave furthered our understanding of the circuitry underlying cortical excitability and how it contributes to cytokinesis. Here, we describe the impact of wounding, which represents both a chemical and a physical signal, on cortical excitability. In early embryos (zygotes to early blastulae), we find that wounding results in a transient cessation (“freezing”) of wave propagation followed by transport of frozen waves toward the wound site. We also find that wounding near cell-cell junctions results in the formation of an F-actin (actin filament)-based structure that pulls the junction toward the wound; at least part of this structure is based on frozen waves. In later embryos (late blastulae to gastrulae), we find that cortical excitability diminishes and is progressively replaced by epithelial excitability, a process in which wounded cells communicate with other cells via wave-like increases of calcium and apical F-actin. While the F-actin waves closely follow the calcium waves in space and time, under some conditions the actin wave can be uncoupled from the calcium wave, suggesting that they may be independently regulated by a common upstream signal. We conclude that as cortical excitability disappears from the level of the individual cell within the embryo, it is replaced by excitability at the level of the embryonic epithelium itself.
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Cell cycle and developmental control of cortical excitability in Xenopus laevis
Here we combine imaging with computational analysis to describe previously unnoticed changes in cortical excitability that respond to both cell cycle and developmental state. We also report two spatially segregated populations of waves: pan-cortical waves that are present throughout the cell cycle and F-actin waves confined to the cleavage furrow.
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- Award ID(s):
- 2132606
- PAR ID:
- 10654927
- Editor(s):
- Wallingford, John
- Publisher / Repository:
- American Society for Cell Biology
- Date Published:
- Journal Name:
- Molecular Biology of the Cell
- Volume:
- 33
- Issue:
- 8
- ISSN:
- 1059-1524
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1091/mbc.E22-01-0025
