Load adaptation by endocytic actin networks.
Load adaptation by endocytic actin networks.
复制标题
内吞肌动蛋白网络的负荷适应。
DOI：
10.1091/mbc.e21-11-0589
复制
发表时间：
2022-05-15
影响因子：
3.3
通讯作者：
Drubin, David G.
中科院分区：
文献类型：
--
作者：
Kaplan, Charlotte;Kenny, Sam J.;Chen, Xuyan;Schoeneberg, Johannes;Sitarska, Ewa;Diz-Munoz, Alba;Akamatsu, Matthew;Xu, Ke;Drubin, David G.
网格蛋白介导的内吞作用（CME）在膜张力升高下的稳健性通过肌动蛋白组装介导的力产生来维持。然而，是否有更多的肌动蛋白组装在内吞位点，以响应增加的负荷以前没有被调查。在这里，肌动蛋白网络超微结构在CME网站进行了检查，在低和高膜张力。肌动蛋白和N-WASP的空间组织表明，肌动蛋白聚合开始在网格蛋白包被的凹坑的基础上，然后网络远离质膜生长。肌动蛋白网络的高度在个别CME网站没有耦合到涂层形状，提高了可能性，局部差异的机械负荷反馈大会。通过操纵膜张力和Arp 2/3复合物的活性，我们测试的假设，肌动蛋白组件在CME网站增加响应于负荷升高。事实上，作为对膜张力升高的反应，肌动蛋白生长得更高，导致网格蛋白涂层的覆盖范围更大，CME减慢。当膜张力升高和Arp 2/3复合物被抑制，浅网格蛋白涂层坑积累，表明这种适应机制是特别重要的涂层曲率的产生。我们建议，肌动蛋白组件增加响应于增加的负载，以确保CME的鲁棒性在一个范围内的质膜张力。
Clathrin-mediated endocytosis (CME) robustness under elevated membrane tension is maintained by actin assembly–mediated force generation. However, whether more actin assembles at endocytic sites in response to increased load has not previously been investigated. Here actin network ultrastructure at CME sites was examined under low and high membrane tension. Actin and N-WASP spatial organization indicate that actin polymerization initiates at the base of clathrin-coated pits and that the network then grows away from the plasma membrane. Actin network height at individual CME sites was not coupled to coat shape, raising the possibility that local differences in mechanical load feed back on assembly. By manipulating membrane tension and Arp2/3 complex activity, we tested the hypothesis that actin assembly at CME sites increases in response to elevated load. Indeed, in response to elevated membrane tension, actin grew higher, resulting in greater coverage of the clathrin coat, and CME slowed. When membrane tension was elevated and the Arp2/3 complex was inhibited, shallow clathrin-coated pits accumulated, indicating that this adaptive mechanism is especially crucial for coat curvature generation. We propose that actin assembly increases in response to increased load to ensure CME robustness over a range of plasma membrane tensions.