Systems Dynamics Behind Cell Movement

Recent studies have shown that the interactions of various molecules are responsible for cell movement. Despite a consensus that systems of molecular interactions mediate the various dynamic properties of cells, it is still intuitively difficult to understand the 'systems dynamics' underlying cell movement. One way to visualize these dynamics is to use a systems-biological approach. The cause-result relationship between molecular interactions and cell movement can be understood as differential equations and their solution. Conceptual models, rather than detailed models, are often of greater use for extracting the essence of systems dynamics. In the first section, we review several mathematical conceptual models proposed for the analysis of cell polarity in migrating cells. The models are classified into four groups: the 'LEGI + MSNL system', the 'CTSP system', the 'MCRD system' and the 'Meinhardt system.' Chemotactic cells, even under normal conditions, do not always migrate with a stable front-back axis, but rather exhibit dynamic behaviors, depending on the conditions. In the second section, we show that MCRD systems composed of multiple species generate dynamic properties, which, in fact, can be observed in chemotaxing cells. The MCRD models with multiple species of molecules shed light on systems dynamics behind cell movement.