Myosin II and Arp2/3 cross-talk governs intracellular hydraulic pressure and lamellipodia formation.
Myosin II and Arp2/3 cross-talk governs intracellular hydraulic pressure and lamellipodia formation.
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DOI：
10.1091/mbc.e20-04-0227
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发表时间：
2021-04-01
影响因子：
3.3
通讯作者：
Petrie RJ
中科院分区：
文献类型：
--
作者：
Patel S;McKeon D;Sao K;Yang C;Naranjo NM;Svitkina TM;Petrie RJ
人成纤维细胞可以在二维表面和三维(3D)基质上的片状脂膜依赖和独立迁移机制之间切换。RhoA GTPase活性控制着从低压片状脂膜到高压叶状脂膜的转换，以响应3D基质的物理结构。抑制这些细胞的肌动球蛋白收缩能力可以降低细胞内的压力，并通过一种未知的机制将叶柄逆转为片状脂膜突起。为了验证高压在物理上防止片状脂血症形成的假设，我们通过激活RhoA或改变细胞外环境和成像细胞突起的渗透压来操纵压力。我们发现，RhoA活性通过两条不同的途径抑制了rac1介导的片状脂血症的形成。首先，RhoA通过增加肌动球蛋白的收缩能力和水的内流来增加细胞内的压力，但作用于rac1的上游以抑制片状脂血症的形成。渗透压的增加揭示了第二个RhoA途径，它通过非肌肉肌球蛋白II(NMII)作用于Rac1下游的片状脂蛋白并升高压力。有趣的是，Arp2/3抑制引发了依赖NMII的细胞内压力增加，并伴随着片状脂体的破坏。综上所述，这些结果表明，肌球蛋白的收缩能力和水内流是协调的，从而增加了细胞内的压力，而RhoA信号可以通过两条不同的途径抑制高压细胞中片状脂血症的形成。
Human fibroblasts can switch between lamellipodia-dependent and -independent migration mechanisms on two-dimensional surfaces and in three-dimensional (3D) matrices. RhoA GTPase activity governs the switch from low-pressure lamellipodia to high-pressure lobopodia in response to the physical structure of the 3D matrix. Inhibiting actomyosin contractility in these cells reduces intracellular pressure and reverts lobopodia to lamellipodial protrusions via an unknown mechanism. To test the hypothesis that high pressure physically prevents lamellipodia formation, we manipulated pressure by activating RhoA or changing the osmolarity of the extracellular environment and imaged cell protrusions. We find RhoA activity inhibits Rac1-mediated lamellipodia formation through two distinct pathways. First, RhoA boosts intracellular pressure by increasing actomyosin contractility and water influx but acts upstream of Rac1 to inhibit lamellipodia formation. Increasing osmotic pressure revealed a second RhoA pathway, which acts through nonmuscle myosin II (NMII) to disrupt lamellipodia downstream from Rac1 and elevate pressure. Interestingly, Arp2/3 inhibition triggered a NMII-dependent increase in intracellular pressure, along with lamellipodia disruption. Together, these results suggest that actomyosin contractility and water influx are coordinated to increase intracellular pressure, and RhoA signaling can inhibit lamellipodia formation via two distinct pathways in high-pressure cells.