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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 63: Cytoskeletal filaments (Joint session BP, CPP)

CPP 63.7: Invited Talk

Thursday, March 19, 2015, 11:30–12:00, H 1028

Cellular chirality arising from the self-organization of the actin cytoskeleton — •Alexander Bershadsky — Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel — Mechanobiology Institute, National University of Singapore, Singapore 117411, Singapore

Cellular mechanisms underlying the development of left-right asymmetry in tissues and embryos remain obscure. Here, the development of a chiral pattern of actomyosin was revealed by studying actin cytoskeleton self-organization in cells with isotropic circular shape. A radially symmetrical system of actin bundles consisting of α-actinin-enriched radial fibers (RFs) and myosin-IIA-enriched transverse fibers (TFs) evolved spontaneously into the chiral system as a result of the unidirectional tilting of all RFs, which was accompanied by a tangential shift in the retrograde movement of TFs. We showed that myosin IIA-dependent contractile stresses within TFs drive their movement along RFs, which grow centripetally in a formin-dependent fashion. The handedness of the chiral pattern was shown to be regulated by α-actinin-1. Computational modeling demonstrated that the dynamics of radial-transverse fiber system can explain the pattern transition from radial to chiral. Thus, actin cytoskeleton self-organization provides built-in machinery that potentially allows cells to develop left-right asymmetry.