Vitriol Eric A, Quintanilla Melissa A, Tidei Joseph J, Troughton Lee D, Cody Abigail, Cisterna Bruno A, Jane Makenzie L, Oakes Patrick W, Beach Jordan R
Department of Neuroscience and Regenerative Medicine, Augusta University, Augusta, GA.
Department of Cell and Molecular Physiology, Stritch School of Medicine, Loyola University Chicago, Maywood, IL.
bioRxiv. 2023 Feb 26:2023.02.24.529920. doi: 10.1101/2023.02.24.529920.
Directed transport of cellular components is often dependent on the processive movements of cytoskeletal motors. Myosin 2 motors predominantly engage actin filaments of opposing orientation to drive contractile events, and are therefore not traditionally viewed as processive. However, recent experiments with purified non-muscle myosin 2 (NM2) demonstrated myosin 2 filaments could move processively. Here, we establish processivity as a cellular property of NM2. Processive runs in central nervous system-derived CAD cells are most apparent as processive movements on bundled actin in protrusions that terminate at the leading edge. We find that processive velocities are consistent with measurements. NM2 makes these processive runs in its filamentous form against lamellipodia retrograde flow, though anterograde movement can still occur in the absence of actin dynamics. Comparing the processivity of NM2 isoforms, we find that NM2A moves slightly faster than NM2B. Finally, we demonstrate that this is not a cell-specific property, as we observe processive-like movements of NM2 in the lamella and subnuclear stress fibers of fibroblasts. Collectively, these observations further broaden NM2 functionality and the biological processes in which the already ubiquitous motor can contribute.
细胞成分的定向运输通常依赖于细胞骨架马达的持续运动。肌球蛋白2马达主要与相反方向的肌动蛋白丝结合以驱动收缩事件,因此传统上不被视为具有持续性。然而,最近对纯化的非肌肉肌球蛋白2(NM2)进行的实验表明,肌球蛋白2丝可以持续移动。在这里,我们确定持续性是NM2的一种细胞特性。在源自中枢神经系统的CAD细胞中的持续运行最明显地表现为在终止于前沿的突起中束状肌动蛋白上的持续运动。我们发现持续速度与测量结果一致。NM2以其丝状形式逆着片状伪足的逆行流进行这些持续运行,尽管在没有肌动蛋白动力学的情况下仍可发生顺行运动。比较NM2亚型的持续性,我们发现NM2A的移动速度比NM2B略快。最后,我们证明这不是细胞特异性特性,因为我们在成纤维细胞的片层和核下应力纤维中观察到了NM2的类似持续运动。总的来说,这些观察结果进一步拓宽了NM2的功能以及这种已经无处不在的马达可能参与的生物学过程。