Fascin-induced actin protrusions are suppressed by dendritic networks in giant unilamellar vesicles.
Fascin-induced actin protrusions are suppressed by dendritic networks in giant unilamellar vesicles.
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DOI：
10.1091/mbc.e21-02-0080
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发表时间：
2021-08-19
影响因子：
3.3
通讯作者：
Liu AP
中科院分区：
文献类型：
--
作者：
Wubshet NH;Bashirzadeh Y;Liu AP
肌动蛋白网络和细胞膜之间的相互作用对真核细胞的功能非常重要，包括细胞形状的改变、运动、极性的建立和粘附。众所周知，肌动蛋白结合蛋白使用有限数量的肌动蛋白单体来形成不同的肌动蛋白网络。肌动蛋白捆绑蛋白束蛋白和肌动蛋白分支蛋白Arp2/3复合物如何竞争重塑膜尚不完全清楚。为了研究束状蛋白和arp2 /3介导的肌动蛋白网络重构，我们采用了一种重构方法，将束状和树突状肌动蛋白网络封装在巨大的单层囊泡（guv）中。独立重组的膜结合Arp2/3成核在guv中形成肌动蛋白皮层，而束状蛋白介导肌动蛋白束的形成，这些肌动蛋白束从guv中突出。无论树突网络是否被膜结合，将束蛋白和Arp2/3复合物包封都会导致极化的树突聚集体，并显著减少膜突起。然而，减少Arp2/3复合体而增加筋膜蛋白可恢复膜突出。这种网络组装的变化以及随后与膜的相互作用可归因于束状蛋白和Arp2/3复合物之间的竞争，以利用有限的肌动蛋白池。
The interactions between actin networks and cell membrane are immensely important for eukaryotic cell functions including cell shape changes, motility, polarity establishment, and adhesion. Actin-binding proteins are known to compete and cooperate using a finite amount of actin monomers to form distinct actin networks. How actin-bundling protein fascin and actin-branching protein Arp2/3 complex compete to remodel membranes is not entirely clear. To investigate fascin- and Arp2/3-mediated actin network remodeling, we applied a reconstitution approach encapsulating bundled and dendritic actin networks inside giant unilamellar vesicles (GUVs). Independently reconstituted, membrane-bound Arp2/3 nucleation forms an actin cortex in GUVs, whereas fascin mediates formation of actin bundles that protrude out of GUVs. Coencapsulating both fascin and Arp2/3 complex leads to polarized dendritic aggregates and significantly reduces membrane protrusions, irrespective of whether the dendritic network is membrane bound or not. However, reducing Arp2/3 complex while increasing fascin restores membrane protrusion. Such changes in network assembly and the subsequent interplay with membrane can be attributed to competition between fascin and Arp2/3 complex to utilize a finite pool of actin.