Bashirzadeh Yashar, Wubshet Nadab H, Liu Allen P
Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI, United States.
Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States.
Front Mol Biosci. 2020 Nov 9;7:610277. doi: 10.3389/fmolb.2020.610277. eCollection 2020.
Depending on the physical and biochemical properties of actin-binding proteins, actin networks form different types of membrane protrusions at the cell periphery. Actin crosslinkers, which facilitate the interaction of actin filaments with one another, are pivotal in determining the mechanical properties and protrusive behavior of actin networks. Short crosslinkers such as fascin bundle F-actin to form rigid spiky filopodial protrusions. By encapsulation of fascin and actin in giant unilamellar vesicles (GUVs), we show that fascin-actin bundles cause various GUV shape changes by forming bundle networks or straight single bundles depending on GUV size and fascin concentration. We also show that the presence of a long crosslinker, α-actinin, impacts fascin-induced GUV shape changes and significantly impairs the formation of filopodia-like protrusions. Actin bundle-induced GUV shape changes are confirmed by light-induced disassembly of actin bundles leading to the reversal of GUV shape. Our study contributes to advancing the design of shape-changing minimal cells for better characterization of the interaction between lipid bilayer membranes and actin cytoskeleton.
根据肌动蛋白结合蛋白的物理和生化特性，肌动蛋白网络在细胞周边形成不同类型的膜突出物。肌动蛋白交联剂促进肌动蛋白丝之间的相互作用，在决定肌动蛋白网络的机械性能和突出行为方面起着关键作用。像丝束蛋白这样的短交联剂将F-肌动蛋白束在一起，形成刚性的刺状丝状伪足突出物。通过将丝束蛋白和肌动蛋白包裹在巨型单层囊泡（GUVs）中，我们发现丝束蛋白-肌动蛋白束根据GUV大小和丝束蛋白浓度形成束网络或直的单束，从而导致各种GUV形状变化。我们还表明，长交联剂α-辅肌动蛋白的存在会影响丝束蛋白诱导的GUV形状变化，并显著损害丝状伪足样突出物的形成。肌动蛋白束诱导的GUV形状变化通过光诱导肌动蛋白束的解体导致GUV形状的逆转得到证实。我们的研究有助于推进形状变化最小细胞的设计，以便更好地表征脂质双分子层膜与肌动蛋白细胞骨架之间的相互作用。
