Crawling locomotion of eukaryotic cells is achieved by a process dependent on the actin cytoskeleton1: protrusion of the leading edge requires assembly of a network of actin filaments2, which must be disassembled at the cell rear for sustained motility. Although ADF/cofilin proteins have been shown to contribute to actin disassembly3, it is not clear how activity of these locally acting proteins could be coordinated over the distance scale of the whole cell. Here we show that non-muscle myosin II has a direct role in actin network disassembly in crawling cells. In fish keratocytes undergoing motility, myosin II is concentrated in regions at the rear with high rates of network disassembly. Activation of myosin II by ATP in detergent-extracted cytoskeletons results in rear-localized disassembly of the actin network. Inhibition of myosin II activity and stabilization of actin filaments synergistically impede cell motility, suggesting the existence of two disassembly pathways, one of which requires myosin II activity. Our results establish the importance of myosin II as an enzyme for actin network disassembly; we propose that gradual formation and reorganization of an actomyosin network provides an intrinsic destruction timer, enabling long-range coordination of actin network treadmilling in motile cells.
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- Supplementary Information (5.4M)
This file contains Supplementary Notes 1-3, Supplementary Figures 1-6 with legends, captions for Supplementary Movies 1-4 and References.
- Supplementary Movie 1 (20.3M)
This movie shows that myosin II inhibition alters actin network Ô¨Çow (see Supplementary Information file for full caption).
- Supplementary Movie 2 (8.4M)
This movie shows that inward traction force generation requires myosin II activity (see Supplementary Information file for full caption).
- Supplementary Movie 3 (15.3M)
This movie shows that jasplakinolide halts actin dynamics of cells in which myosin II is inhibited (see Supplementary Information file for full caption).
- Supplementary Movie 4 (424K)
This movie shows that actin network disassembly in the rear of detergent-extracted keratocyte cytoskeletons is ATP-dependent and blebbistatin-sensitive (see Supplementary Information file for full caption).