Molecular motors robustly drive active gels to a critically connected state
By J. Alvarado, M. Sheinman, Abhinav Sharma, F. MacKintosh, G. Koenderink. Nature Physics, 2013
220 citations recorded by the source corpus.
Living systems naturally exhibit internal driving: active, molecular processes drive non-equilibrium phenomena such as metabolism or migration. Active gels constitute a fascinating class of internally driven matter, in which molecular motors exert localized stresses inside polymer networks. There is evidence that network crosslinking is required to allow motors to induce macroscopic contraction. Yet a quantitative understanding of how network connectivity enables contraction is lacking. Here we show experimentally that myosin motors contract crosslinked actin polymer networks to clusters with a scale-free size distribution. This critical behaviour occurs over an unexpectedly broad range of crosslink concentrations. To understand this robustness, we developed a quantitative model of contractile networks that takes into account network restructuring: motors reduce connectivity by forcing crosslinks to unbind. Paradoxically, to coordinate global contractions, motor activity should be low. Otherwise, motors drive initially well-connected networks to a critical state where ruptures form across the entire network. A study of an actomyosin active gel now demonstrates the importance of the crosslinking density of actin polymers in enabling myosin motors to internally drive contraction and rupture the network into clusters. These results could help us to better understand the role of the cytoskeleton in cell division and tissue morphogenesis.
Subfields: Cell Biology, Condensed Matter Physics, Physiology
View Paper: https://www.semanticscholar.org/paper/46d060c021b2729d0ab59858b76e9296469a7012
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Citations in the corpus
- Colloquium: Criticality and dynamical scaling in living systems (2017, background): “…oscillators such as circadian clocks (Garcia-Ojalvo et al., 2004); (ii) percolation transitions of fibers in connective tissues such as collagen (Alvarado et al., 2013; Forgacs et al., 1991; Newman et al., 2004), (iii) melting phase transition in DNA strands (Li and Retzloff, 2006; Poland and…”
- Modeling semiflexible polymer networks (2014, background): “Recently, however, several groups have begun to study networks in which molecular motors drive the system to effectively lower connectivity (Köhler et al., 2011; Murrell and Gardel, 2012; Soares e Silva et al., 2011), and even to a state resembling a critical point (Alvarado et al., 2013).”