Berlin 2012 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 6: Physics of Cells II
BP 6.7: Vortrag
Montag, 26. März 2012, 16:45–17:00, H 1028
A theory of sarcomeric pattern formation by actin cluster coalescence — •Benjamin M Friedrich1,3, Elisabeth Fischer-Friedrich2,3, Nir S Gov2, and Samuel A Safran1 — 1Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot, Israel — 2Department of Chemical Physics, Weizmann Institute of Science, Rehovot, Israel — 3Current address: Max-Planck Institute for the Physics of Complex Systems, Dresden, Germany
Contractile function of striated muscle cells depends crucially on the almost crystalline order of actin and myosin filaments in myofibrils, but the physical mechanisms of myofibril assembly remains ill-defined. Passive diffusive sorting of actin filaments into sarcomeric order is kinetically impossible, suggesting a pivotal role of active processes in sarcomeric pattern formation. Using a computational model, we show that actin filament treadmilling in the presence of processive plus-end crosslinking provides a simple and robust mechanism for the polarity sorting of actin filaments. We propose that the coalescence of crosslinked actin clusters could be key for sarcomeric pattern formation. In our simulations, sarcomere spacing is set by filament length prompting tight length control already at early stages of pattern formation. The proposed mechanism could be generic and apply both to premyofibrils and nascent myofibrils in developing muscle cells as well as possibly to striated stress-fibers in non-muscle cells.