Impact of the carbazole derivative wiskostatin on mechanical stability and dynamics of motile cells
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Many essential functions in eukaryotic cells like phagocytosis, division, and motility rely on the dynamical properties of the actin cytoskeleton. A central player in the actin system is the Arp2/3 complex. Its activity is controlled by members of the WASP (Wiskott–Aldrich syndrome protein) family. In this work, we investigated the effect of the carbazole derivative wiskostatin, a recently identified N-WASP inhibitor, on actin-driven processes in motile cells of the social ameba Dictyostelium discoideum. Drug-treated cells exhibited an altered morphology and strongly reduced pseudopod formation. However, TIRF microscopy images revealed that the overall cortical network structure remained intact. We probed the mechanical stability of wiskostatin-treated cells using a microfluidic device. While the total amount of F-actin in the cells remained constant, their stiffness was strongly reduced. Furthermore, wiskostatin treatment enhanced the resistance to fluid shear stress, while spontaneous motility as well as chemotactic motion in gradients of cAMP were reduced. Our results suggest that wiskostatin affects the mechanical integrity of the actin cortex so that its rigidity is reduced and actin-driven force generation is impaired.
KeywordsActin dynamics Wiskostatin Dictyostelium discoideum
We thank Achim Quaas for assistance with the MATLAB algorithms, Christian Fiedler for support on the F-actin assay, Kirsten Krüger for assistance in cell culture, and Douwe Veltman for discussions. We thank Prof. Bernd Walz for generous access to his Zeiss LSM 710 confocal microscope and Prof. Otto Baumann for continuous help in operating the microscope. Financial support by the Deutsche Forschungsgemeinschaft (DFG BE 3978/3-1) is gratefully acknowledged.
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