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Formation of contractile networks and fibers in the medial cell cortex through myosin‐II turnover, contraction, and stress‐stabilization
Author(s) -
Nie Wei,
Wei MingTzo,
OuYang H. Daniel,
Jedlicka Sabrina S.,
Vavylonis Dimitrios
Publication year - 2015
Publication title -
cytoskeleton
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.95
H-Index - 86
eISSN - 1949-3592
pISSN - 1949-3584
DOI - 10.1002/cm.21207
Subject(s) - myosin , biophysics , biology , cytoskeleton , contraction (grammar) , cell cortex , molecular motor , stress fiber , microbiology and biotechnology , muscle contraction , actin , anatomy , cell , biochemistry , endocrinology
The morphology of adhered cells depends crucially on the formation of a contractile meshwork of parallel and cross‐linked fibers along the contacting surface. The motor activity and minifilament assembly of non‐muscle myosin‐II is an important component of cortical cytoskeletal remodeling during mechanosensing. We used experiments and computational modeling to study cortical myosin‐II dynamics in adhered cells. Confocal microscopy was used to image the medial cell cortex of HeLa cells stably expressing myosin regulatory light chain tagged with GFP (MRLC‐GFP). The distribution of MRLC‐GFP fibers and focal adhesions was classified into three types of network morphologies. Time‐lapse movies show: myosin foci appearance and disappearance; aligning and contraction; stabilization upon alignment. Addition of blebbistatin, which perturbs myosin motor activity, leads to a reorganization of the cortical networks and to a reduction of contractile motions. We quantified the kinetics of contraction, disassembly and reassembly of myosin networks using spatio‐temporal image correlation spectroscopy (STICS). Coarse‐grained numerical simulations include bipolar minifilaments that contract and align through specified interactions as basic elements. After assuming that minifilament turnover decreases with increasing contractile stress, the simulations reproduce stress‐dependent fiber formation in between focal adhesions above a threshold myosin concentration. The STICS correlation function in simulations matches the function measured in experiments. This study provides a framework to help interpret how different cortical myosin remodeling kinetics may contribute to different cell shape and rigidity depending on substrate stiffness. © 2015 Wiley Periodicals, Inc.