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Models and sensory limits in chemotaxis of eukaryotic cells

When exposed to spatiotemporal variations in concentration of a specific chemical compound, several types of motile eukaryotic cells respond by orientating their movement towards the source of chemoattractant. The phenomenon of chemotaxis plays crucial role in numerous fundamental biological processes such as cellular immune response, cancer metastasis, wound healing, and embryonic development. Chemotaxis is mediated by chemoattractant receptors at the cell membrane, which transduce information about extracellular distribution of a chemoattractant to intracellular signaling networks that in turn regulate motile machinery of the cell. Research on chemotaxis of Dictyostelium cells, which utilize 3'-5'-cyclic adenosine monophosphate as a chemoattractant during aggregation, has contributed fundamentally to the present knowledge about this process. I will present most important facts known about chemotaxis in Dictyostelium cells, draw parallels to similar processes in other types of eukaryotic cells, and sketch the dominant biological models of intracellular signaling pathways involved in chemotaxis. Further, I will discuss the fundamental and practical limits to sensitivity of cells to weak external stimuli, and to accuracy of their directional orientation. Particular attention will be paid to the influence of noise, which is inherent to molecular signaling, on the sensory limits in chemotaxis. Finally, means at a cell’ s disposal to enhance its efficiency as a chemotactic sensor will be illustrated by the example of cell elongation.

Chemotaxis; Dictyostelium

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