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DY: Fachverband Dynamik und Statistische Physik

DY 54: Statistical Physics of Biological Systems I (joint session BP/DY)

DY 54.5: Vortrag

Donnerstag, 15. März 2018, 10:30–10:45, H 2013

Cell polarization in elliptical geometry: how does C. Elegans determine its first axis? — •Raphaela Geßele, Jacob Halatek, and Erwin Frey — Department of Physics, Ludwig-Maximilians-Universität München, 80333 Munich, Germany

Cell polarity defines axes that guide cell differentiation and division. In the single cell state of the Caenorhabditis Elegans embryo, PAR protein patterns determine the anterior-posterior axis which further guides the first cleavage. Experiment and theory have indicated that mutual binding inhibition of (anterior) aPAR and (posterior) pPAR proteins is the key mechanism of polarity maintenance by the PAR reaction-diffusion network. Strikingly, our analysis of the reaction-diffusion dynamics in (elliptical) cellular geometry shows that mutual inhibition alone does not lead to a stable polarity along the long (anterior-posterior) axis of the cell but generically favors polarity by aPAR and pPAR protein domains aligned with the short axis. We find that the geometry adaption of the patterning process depends on an intricate interplay between attachment-detachment dynamics on the one hand, and cytosolic reactivation on the other hand. Our findings show that the local ratio of membrane surface to cytosolic bulk volume is the main geometric cue to which patterns adapt. Furthermore, an inactive phase after membrane detachment can switch the preferred polarity axis - The decisive parameter for switching is the diffusion length of the inactive phase. In conclusion, our studies reveal the crucial role of geometry for self-organized pattern formation. Geometry should be explicitly considered in models for intracellular pattern formation.