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Actin shells control buckling and wrinkling of biomembranes

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Global changes of cell shape under mechanical or osmotic external stresses are mostly controlled by the mechanics of the cortical actin cytoskeleton underlying the cell membrane. Some aspects of this process can be recapitulated in vitro on reconstituted actin-and-membrane systems. In this paper, we investigate how the mechanical properties of a branched actin network shell, polymerized at the surface of a liposome, control membrane shape when the volume is reduced. We observe a variety of membrane shapes depending on the actin thickness. Thin shells undergo buckling, characterized by a cup-shape deformation of the membrane that coincides with the one of the actin network. Thick shells produce membrane wrinkles, but do not deform their outer layer. For intermediate micrometer-thick shells, wrinkling of the membrane is observed, and the actin layer is slightly deformed. Confronting our experimental results with a theoretical description, we determine the transition between buckling and wrinkling, which depends on the thickness of the actin shell and the size of the liposome. We thus unveil the generic mechanism by which biomembranes are able to accommodate their shape against mechanical compression, through thickness adaptation of their cortical cytoskeleton.

Graphical abstract: Actin shells control buckling and wrinkling of biomembranes

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Publication details

The article was received on 20 Sep 2019, accepted on 31 Oct 2019 and first published on 06 Nov 2019

Article type: Paper
DOI: 10.1039/C9SM01902B
Soft Matter, 2019, Advance Article

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    Actin shells control buckling and wrinkling of biomembranes

    R. Kusters, C. Simon, R. Lopes Dos Santos, V. Caorsi, S. Wu, J. Joanny, P. Sens and C. Sykes, Soft Matter, 2019, Advance Article , DOI: 10.1039/C9SM01902B

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