1 Department of Neurology, Yale University School of Medicine, New Haven, CT, USA.
2 Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT, USA.
Mol Pain. 2018 Jan-Dec;14:1744806918788638. doi: 10.1177/1744806918788638. Epub 2018 Jun 29.
Sodium channels play pivotal roles in health and diseases due to their ability to control cellular excitability. The pore-forming α-subunits (sodium channel alpha subunits) of the voltage-sensitive channels (i.e., Na1.1-1.9) and the nonvoltage-dependent channel (i.e., Na) share a common structural motif and selectivity for sodium ions. We hypothesized that the actin-based nonmuscle myosin II motor proteins, nonmuscle myosin heavy chain-IIA/myh9, and nonmuscle myosin heavy chain-IIB/myh10 might interact with sodium channel alpha subunits to play an important role in their transport, trafficking, and/or function. Immunochemical and electrophysiological assays were conducted using rodent nervous (brain and dorsal root ganglia) tissues and ND7/23 cells coexpressing Na subunits and recombinant myosins. Immunoprecipitation of myh9 and myh10 from rodent brain tissues led to the coimmunoprecipitation of Na, Na1.2, and Na1.3 subunits, but not Na1.1 and Na1.6 subunits, expressed there. Similarly, immunoprecipitation of myh9 and myh10 from rodent dorsal root ganglia tissues led to the coimmunoprecipitation of Na1.7 and Na1.8 subunits, but not Na1.9 subunits, expressed there. The functional implication of one of these interactions was assessed by coexpressing myh10 along with Na1.8 subunits in ND7/23 cells. Myh10 overexpression led to three-fold increase ( P < 0.01) in the current density of Na1.8 channels expressed in ND7/23 cells. Myh10 coexpression also hyperpolarized voltage-dependent activation and steady-state fast inactivation of Na1.8 channels. In addition, coexpression of myh10 reduced ( P < 0.01) the offset of fast inactivation and the amplitude of the ramp currents of Na1.8 channels. These results indicate that nonmuscle myosin heavy chain-IIs interact with sodium channel alpha subunits subunits in an isoform-dependent manner and influence their functional properties.
钠通道在健康和疾病中起着关键作用，因为它们能够控制细胞的兴奋性。电压敏感通道（即 Na1.1-1.9）和非电压依赖性通道（即 Na）的孔形成α亚基（钠通道α亚基）具有共同的结构基序和对钠离子的选择性。我们假设基于肌动蛋白的非肌肉肌球蛋白 II 运动蛋白，非肌肉肌球蛋白重链-IIA/myh9 和非肌肉肌球蛋白重链-IIB/myh10 可能与钠通道 α 亚基相互作用，在其运输、运输和/或功能中发挥重要作用。使用啮齿动物神经（大脑和背根神经节）组织和共表达 Na 亚基和重组肌球蛋白的 ND7/23 细胞进行免疫化学和电生理学测定。从啮齿动物脑组织中免疫沉淀 myh9 和 myh10 导致共免疫沉淀表达的 Na、Na1.2 和 Na1.3 亚基，但不沉淀表达的 Na1.1 和 Na1.6 亚基。同样，从啮齿动物背根神经节组织中免疫沉淀 myh9 和 myh10 导致共免疫沉淀表达的 Na1.7 和 Na1.8 亚基，但不沉淀表达的 Na1.9 亚基。这些相互作用之一的功能意义通过在 ND7/23 细胞中与 Na1.8 亚基共表达 myh10 来评估。myh10 的过表达导致在 ND7/23 细胞中表达的 Na1.8 通道的电流密度增加三倍（P<0.01）。myh10 共表达还使 Na1.8 通道的电压依赖性激活和稳态快速失活超极化。此外，myh10 的共表达减少（P<0.01）Na1.8 通道的快速失活偏移和斜坡电流幅度。这些结果表明，非肌肉肌球蛋白重链-II 以依赖于亚型的方式与钠通道α 亚基相互作用，并影响它们的功能特性。
