Department of Health Sciences, Boston University, Boston, MA, USA.
CSIR-Institute of Himalayan Bioresource Technology, Palampur, India.
J Cell Mol Med. 2021 Mar;25(5):2471-2483. doi: 10.1111/jcmm.16170. Epub 2021 Feb 6.
Non-muscle myosin II (NMII) plays a role in many fundamental cellular processes including cell adhesion, migration, and cytokinesis. However, its role in mammalian vascular function is not well understood. Here, we investigated the function of NMII in the biomechanical and signalling properties of mouse aorta. We found that blebbistatin, an inhibitor of NMII, decreases agonist-induced aortic stress and stiffness in a dose-dependent manner. We also specifically demonstrate that in freshly isolated, contractile, aortic smooth muscle cells, the non-muscle myosin IIA (NMIIA) isoform is associated with contractile filaments in the core of the cell as well as those in the non-muscle cell cortex. However, the non-muscle myosin IIB (NMIIB) isoform is excluded from the cell cortex and colocalizes only with contractile filaments. Furthermore, both siRNA knockdown of NMIIA and NMIIB isoforms in the differentiated A7r5 smooth muscle cell line and blebbistatin-mediated inhibition of NM myosin II suppress agonist-activated increases in phosphorylation of the focal adhesion proteins FAK Y925 and paxillin Y118. Thus, we show in the present study, for the first time that NMII regulates aortic stiffness and stress and that this regulation is mediated through the tension-dependent phosphorylation of the focal adhesion proteins FAK and paxillin.
非肌肉肌球蛋白 II（NMII）在许多基本的细胞过程中发挥作用，包括细胞黏附、迁移和胞质分裂。然而，其在哺乳动物血管功能中的作用尚不清楚。在这里，我们研究了 NMII 在小鼠主动脉的生物力学和信号特性中的功能。我们发现，NMII 的抑制剂 blebbistatin 以剂量依赖的方式降低激动剂诱导的主动脉张力和僵硬。我们还特别证明，在新鲜分离的、收缩的、主动脉平滑肌细胞中，非肌肉肌球蛋白 IIA（NMIIA）同工型与细胞核心中的收缩纤维以及非肌肉细胞皮质中的收缩纤维相关。然而，非肌肉肌球蛋白 IIB（NMIIB）同工型被排除在细胞皮质之外，仅与收缩纤维共定位。此外，在分化的 A7r5 平滑肌细胞系中，NMIIA 和 NMIIB 同工型的 siRNA 敲低以及 blebbistatin 介导的 NM 肌球蛋白 II 抑制，均可抑制激动剂激活后粘着斑蛋白 FAK Y925 和桩蛋白 Y118 的磷酸化增加。因此，我们在本研究中首次表明，NMII 调节主动脉僵硬和张力，这种调节是通过粘着斑蛋白 FAK 和桩蛋白 Y118 的张力依赖性磷酸化介导的。
