Spring 2016
Seminars are held at 11:30AM in Cullimore Hall, Room 611, unless noted otherwise. For questions about the seminar schedule, please contact Casey Diekman.
Date: March 22, 2016
Speaker: Dietmar Oelz
Courant Institute of Mathematical Sciences,
New York University
Title: "Force Generation and Contraction of Random Actomyosin Bundles"
Abstract:
Cytokinetic rings and stress fibers generate effective contraction, but how respective actomyosin arrays are organized and and how semi-random actomyosin bundles generate contraction is not clear. We investigate computationally the self-organization and contraction of an actomyosin ring that is completely disorganized initially. To this end, we formulate a detailed agent-based model for a 1D chain of cross-linked actin filaments forming a closed ring interspersed with myosin-II motor proteins.
The result of our numerical experiments is that in order to contract, 1) actin filaments in the ring have to turn over, 2) myosin motors have to be processive, and 3) filaments have to be sufficiently crosslinked. Our simulations predict, in agreement with experimental observations, that the rate of contraction is constant and the time of contraction is invariant with respect to the original ring size.
Moreover, the model demonstrates that with time, a pattern formation takes place in the ring worsening the contractile process. The more random actin dynamics are, the longer the actomyosin ring stays disorganized and the higher the contractile force and rate it generates.
Finally we derive a continuum model as a short filament limit of the agent based model. The model features highly nontrivial pattern formation and traveling wave solutions and explains the aggregation of actin and myosin predicted by the microscopic model.