Long-range self-organization of cytoskeletal myosin II filament stacks. Nature Cell Biology, February 2017.

By Shiqiong Hu1, Kinjal Dasbiswas2,3, Zhenhuan Guo1, Yee-Han Tee1, Visalatchi Thiagarajan1, Pascal Hersen1,4, Teng-Leong Chew5, Samuel A. Safran2, Ronen Zaidel-Bar1, Alexander D. Bershadsky1,6

Nature Cell Biology. February 2017. 19(2). 133-141. doi: 10.1038/ncb3466.

Abstract

Although myosin II filaments are known to exist in non-muscle cells, their dynamics and organization are incompletely understood. Here, we combined structured illumination microscopy with pharmacological and genetic perturbations, to study the process of actomyosin cytoskeleton self-organization into arcs and stress fibres. A striking feature of the myosin II filament organization was their ‘registered’ alignment into stacks, spanning up to several micrometres in the direction orthogonal to the parallel actin bundles. While turnover of individual myosin II filaments was fast (characteristic half-life time 60 s) and independent of actin filament turnover, the process of stack formation lasted a longer time (in the range of several minutes) and required myosin II contractility, as well as actin filament assembly/disassembly and crosslinking (dependent on formin Fmnl3, cofilin1 and α-actinin-4). Furthermore, myosin filament stack formation involved long-range movements of individual myosin filaments towards each other suggesting the existence of attractive forces between myosin II filaments. These forces, possibly transmitted via mechanical deformations of the intervening actin filament network, may in turn remodel the actomyosin cytoskeleton and drive its self-organization.

 

1Mechanobiology Institute, National University of Singapore, Singapore 117411, Singapore.
2Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot 76100, Israel.
3James Franck Institute, University of Chicago, Chicago, Illinois 60637, USA.
4Laboratoire Matire et Systèmes Complexes, UMR 7057 CNRS &Université Paris Diderot, Paris 75013, France.
5Advanced Imaging Center, HHMI Janelia Research Campus, Ashburn, Virginia 20147, USA.
6Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel.