RT Journal Article
SR Electronic
T1 Polarity sorting drives remodeling of actin-myosin networks
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 314484
DO 10.1101/314484
A1 Viktoria Wollrab
A1 Julio M. Belmonte
A1 Maria Leptin
A1 François Nédeléc
A1 Gijsje H. Koenderink
YR 2018
UL http://biorxiv.org/content/early/2018/05/04/314484.abstract
AB Cytoskeletal networks of actin filaments and myosin motors drive many dynamic cell processes. A key characteristic of these networks is their contractility. Despite intense experimental and theoretical efforts, it is not clear what mechanism favors network contraction over expansion. Recent work points to a dominant role for the nonlinear mechanical response of actin filaments, which can withstand stretching but buckle upon compression. Here we present an alternative mechanism. We study how interactions between actin and myosin-2 at the single filament level translate into contraction at the network scale by performing time-lapse imaging on reconstituted quasi-2D-networks mimicking the cell cortex. We observe myosin end-dwelling after it runs processively along actin filaments. This leads to transport and clustering of actin filament ends and the formation of transiently stable bipolar structures. Further we show that myosin-driven polarity sorting leads to polar actin aster formation, which act as contractile nodes that drive contraction in crosslinked networks. Computer simulations comparing the roles of the end-dwelling mechanism and a buckling-dependent mechanism show that the relative contribution of end-dwelling contraction increases as the network mesh-size decreases.