Hypotonicity activates a voltage-dependent membrane conductance in N2a neuroblastoma cells.
Hypotonicity activates a voltage-dependent membrane conductance in N2a neuroblastoma cells.
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DOI：
10.1016/j.bbrc.2017.01.118
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发表时间：
2017-03
影响因子：
3.1
通讯作者：
Akiyuki Taruno;Y. Marunaka
中科院分区：
文献类型：
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作者：
Akiyuki Taruno;Y. Marunaka
为了维持细胞和身体的稳态，细胞通过激活各种离子通道来响应包括渗透应激在内的细胞外刺激，这些离子通道与许多生理和病理生理条件有关。然而，细胞神经感觉机制仍然难以捉摸。在这里，我们报告了一种新的电压依赖性电流在N2a细胞激活暴露于低渗应力。在低渗激发后，N2a细胞依次产生两种不同的电流。体积调节阴离子通道（VRAC）电流首先出现，延迟后，激活先前未表征的强烈外向整流电流。后者，延迟电流（Id）对NPPB（一种Cl−通道的非特异性阻断剂）和细胞内Mg2+（抑制VRAC和肿胀激活的TRPM3和TRPM7通道）不敏感。用NMDG+替代细胞外Na+可降低内向尾电流，表明Idis由阳离子介导。最后，Id显示了具有缓慢激活动力学的电压依赖性激活和+76 mV下的半最大激活。这些药理学和生物物理学特性ofIdare不同于那些已知的渗透细胞溶胀激活离子通道。总之，我们的数据确定和表征一种新的神经激活，电压依赖性离子通道在N2a细胞。
To maintain cellular and bodily homeostasis, cells respond to extracellular stimuli including osmotic stress by activating various ion channels, which have been implicated in many physiological and pathophysiological conditions. However, cellular osmosensory mechanisms remain elusive. Here, we report a novel voltage-dependent current in N2a cells activated by exposure to hypotonic stress. After a hypotonic challenge, N2a cells sequentially develop two distinct currents. The volume-regulated anion channel (VRAC) current emerges first and, after a delay, activation of a previously uncharacterized strongly outwardly rectifying current follows. The latter, delayed current (Id) is insensitive to NPPB, a nonspecific blocker of Cl−channels, and intracellular Mg2+, which inhibits VRAC and swelling-activated TRPM3 and TRPM7 channels. Replacement of extracellular Na+with NMDG+reduces inward tail currents, suggesting thatIdis mediated by cations. Finally,Idshows voltage-dependent activation with slow activation kinetics and half-maximal activation at +76 mV. These pharmacological and biophysical characteristics ofIdare distinct from those of known osmotic cell swelling-activated ion channels. In conclusion, our data identify and characterize a novel osmotically-activated, voltage-dependent ion channel in N2a cells.