Mechanosensitivity of N-type calcium channel currents
Mechanosensitivity of N-type calcium channel currents
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DOI：
10.1016/s0006-3495(02)75267-3
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发表时间：
2002-11-01
影响因子：
3.4
通讯作者：
Morris, CE
中科院分区：
文献类型：
--
作者：
Calabrese, B;Tabarean, IV;Morris, CE
电压门控钙通道中的机械敏感性可能是健康细胞中钙信号传导的资产，也可能是创伤期间的负债。HEK细胞中表达的重组N型通道揭示了一系列机械响应。当在全细胞钳下用静水压力使细胞膨胀时，电容不变，但峰值电流可逆地增加了约1.5倍，与膨胀有关，而与施加的压力无关。此外，拉伸瞬时增加了开放状态的失活率，不可逆地增加了关闭状态的失活率，并左移失活，而不影响激活曲线或速率。不可逆的机械反应被证明是机械加速组件的运行，他们是不明显的细胞附着的记录，然而，可逆的拉伸诱导的峰值电流持续增加。T型通道（仅α（1b）亚基）在单独表达或与N型通道（α（1B）和两个辅助亚基）共表达时对机械不敏感，并与增加N型电流的拉伸共刺激。沿着细胞附着的结果，这种差异效应表明N型机械敏感性不依赖于记录情况。T-型电流对牵拉的不敏感性表明N-型机械响应可能来自初级/辅助亚基相互作用。然而，在单通道记录中，无论α（1B）亚基单独表达还是与辅助亚基一起表达，N型电流都表现出可逆的牵张诱导的NPo增加。这些发现为钙电流机械敏感性的分子解剖奠定了基础。
Mechanosensitivity in voltage-gated calcium channels could be an asset to calcium signaling in healthy cells or a liability during trauma. Recombinant N-type channels expressed in HEK cells revealed a spectrum of mechano-responses. When hydrostatic pressure inflated cells under whole-cell clamp, capacitance was unchanged, but peak current reversibly increased similar to1.5-fold, correlating with inflation, not applied pressure. Additionally, stretch transiently increased the open-state inactivation rate, irreversibly increased the closed-state inactivation rate, and left-shifted inactivation without affecting the activation curve or rate. Irreversible mechano-responses proved to be mechanically accelerated components of run-down; they were not evident in cell-attached recordings where, however, reversible stretch-induced increases in peak current persisted. T-type channels (alpha(1b) subunit only) were mechano-insensitive when expressed alone or when coexpressed with N-type channels (alpha(1B) and two auxiliary subunits) and costimulated with stretch that augmented N-type current. Along with the cell-attached results, this differential effect indicates that N-type mechanosensitivity did not depend on the recording situation. The insensitivity of T-type currents to stretch suggested that N-type mechano-responses might arise from primary/auxiliary subunit interactions. However, in single-channel recordings, N-type currents exhibited reversible stretch-induced increases in NPo whether the alpha(1B) subunit was expressed alone or with auxiliary subunits. These findings set the stage for the molecular dissection of calcium current mechanosensitivity.