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Sci. Signal., 14 December 2010
Vol. 3, Issue 152, p. ra89
Cells that migrate up a gradient of chemoattractant, a process known as chemotaxis, do so by producing membrane protrusions called pseudopods. Various models have been proposed to describe how pseudopods form and drive cell movement and navigation. Otsuji et al. performed simulations of migrating cells and observed cells undergoing chemotaxis, enabling them to develop a conceptual model to explain pseudopod formation. Their model is based on two interacting molecules, "A" and "B," such that A promotes membrane protrusion (and pseudopod formation), whereas B promotes membrane retraction. A and B cycle between the membrane and the cytosol, and they have diffusion rates that are slower in the membrane than in the cytosol. Instabilities in the model, based on differential diffusion, combine to promote competition between potential pseudopods, such that one is favored; such instabilities also lead to the periodic splitting of a pseudopod into two "peaks," only one of which persists. The surviving pseudopods often exhibit an alternating left-right pattern that aids migration. Although the environment through which a cell migrates is likely more complex than the model assumes, this general model suggests a simple explanation for pseudopod formation and cell migration.
Citation: M. Otsuji, Y. Terashima, S. Ishihara, S. Kuroda, K. Matsushima, A Conceptual Molecular Network for Chemotactic Behaviors Characterized by Feedback of Molecules Cycling Between the Membrane and the Cytosol. Sci. Signal.3, ra89 (2010).