Amoeboid cells are fundamental to animal biology and broadly distributed across animal diversity, but their evolutionary origin is unclear. The closest living relatives of animals, the choanoflagellates, display a polarized cell architecture (with an apical flagellum encircled by microvilli) that closely resembles that of epithelial cells and suggests homology, but this architecture differs strikingly from the deformable phenotype of animal amoeboid cells. Here, we show that choanoflagellates subjected to confinement differentiate into an amoeboid form by retracting their flagella and activating myosin-based motility. This switch allows escape from confinement and is conserved across choanoflagellate diversity. The conservation of the amoeboid cell phenotype across animals and choanoflagellates, together with the conserved role of myosin, is consistent with the homology of amoeboid motility in both lineages. We hypothesize that the differentiation between animal epithelial and crawling cells might have evolved from a stress-induced phenotypic switch between flagellate and amoeboid forms in their single-celled ancestors.
All data generated or analysed during this study are included in the manuscript and supporting files.
- Nicole King
- Thibaut Brunet
- Thibaut Brunet
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
- Iñaki Ruiz-Trillo, CSIC-Universitat Pompeu Fabra, Spain
© 2021, Brunet et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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