Biophysical basis for Kv1.3 regulation of membrane potential changes induced by P2X4-mediated calcium entry in microglia.
Biophysical basis for Kv1.3 regulation of membrane potential changes induced by P2X4-mediated calcium entry in microglia.
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作者：
Nguyen HM;di Lucente J;Chen YJ;Cui Y;Ibrahim RH;Pennington MW;Jin LW;Maezawa I;Wulff H
小胶质细胞介导的炎症在缺血性中风和阿尔茨海默病(AD)等神经退行性疾病中产生不利影响。电压门控性钾通道Kv1.3的表达是小胶质细胞激活所必需的。Kv1.3基因缺失和药物抑制均能有效减少小胶质细胞的激活和相关的炎症反应，并改善AD和缺血性卒中动物模型的神经预后。在这里，我们试图阐明Kv1.3抑制治疗作用的分子机制，这些机制仍然不完全清楚。结合全细胞电压钳电生理和定量聚合酶链式反应(QPCR)，我们首次在体外和体内研究了Kv1.3和主要的ATP门控阳离子通道P2X4的刺激依赖性差异表达模式。然后，我们通过全细胞电流钳实验证明，Kv1.3通道不仅有助于设置静息膜电位，而且在对抗去极化电流注入引起的膜电位过度变化中发挥重要作用。同样，Kv1.3通道的存在使小胶质细胞对ATP介导的P2X4受体激活产生的去极化具有更强的抵抗力。用ShK-223抑制Kv1.3通道后，Kv1.3使膜电位变化正常化的能力完全丧失，导致过度去极化，减少了通过P2X4受体的钙瞬变。因此，我们的报告将Kv1.3的功能与P2X4受体介导的信号转导联系起来，这是Kv1.3阻断减少小胶质细胞介导的炎症的潜在机制之一。虽然我们可以证实之前报道的男性和女性之间在小胶质细胞P2X4表达上的差异，但在体外和体内，小胶质细胞Kv1.3的表达没有性别差异。电压门控性K+通道Kv1.3调节小胶质细胞膜电位。抑制Kv1.3可使小胶质细胞去极化，并通过驱散钙离子的电化学驱动力，减少由P2X4受体介导的钙离子内流。电压门控性K+通道Kv1.3调节小胶质细胞膜电位。抑制Kv1.3可使小胶质细胞去极化，并通过驱散钙离子的电化学驱动力，减少由P2X4受体介导的钙离子内流。
Microglia‐mediated inflammation exerts adverse effects in ischemic stroke and in neurodegenerative disorders such as Alzheimer's disease (AD). Expression of the voltage‐gated potassium channel Kv1.3 is required for microglia activation. Both genetic deletion and pharmacological inhibition of Kv1.3 are effective in reducing microglia activation and the associated inflammatory responses, as well as in improving neurological outcomes in animal models of AD and ischemic stroke. Here we sought to elucidate the molecular mechanisms underlying the therapeutic effects of Kv1.3 inhibition, which remain incompletely understood. Using a combination of whole‐cell voltage‐clamp electrophysiology and quantitative PCR (qPCR), we first characterized a stimulus‐dependent differential expression pattern for Kv1.3 and P2X4, a major ATP‐gated cationic channel, both in vitro and in vivo. We then demonstrated by whole‐cell current‐clamp experiments that Kv1.3 channels contribute not only to setting the resting membrane potential but also play an important role in counteracting excessive membrane potential changes evoked by depolarizing current injections. Similarly, the presence of Kv1.3 channels renders microglia more resistant to depolarization produced by ATP‐mediated P2X4 receptor activation. Inhibiting Kv1.3 channels with ShK‐223 completely nullified the ability of Kv1.3 to normalize membrane potential changes, resulting in excessive depolarization and reduced calcium transients through P2X4 receptors. Our report thus links Kv1.3 function to P2X4 receptor‐mediated signaling as one of the underlying mechanisms by which Kv1.3 blockade reduces microglia‐mediated inflammation. While we could confirm previously reported differences between males and females in microglial P2X4 expression, microglial Kv1.3 expression exhibited no gender differences in vitro or in vivo. The voltage‐gated K+ channel Kv1.3 regulates microglial membrane potential. Inhibition of Kv1.3 depolarizes microglia and reduces calcium entry mediated by P2X4 receptors by dissipating the electrochemical driving force for calcium. The voltage‐gated K+ channel Kv1.3 regulates microglial membrane potential. Inhibition of Kv1.3 depolarizes microglia and reduces calcium entry mediated by P2X4 receptors by dissipating the electrochemical driving force for calcium.
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影响因子：
6.3
作者：
Chen, Yi-Je;Nguyen, Hai M.;Wulff, Heike
通讯作者：
Wulff, Heike
影响因子：
5.3
作者：
Jung, S;Aliberti, J;Littman, DR
通讯作者：
Littman, DR
影响因子：
2.5
作者：
Chung, S;Jung, W;Lee, MY
通讯作者：
Lee, MY
影响因子：
6.3
作者：
Chen, Yi-Je;Raman, Girija;Wulff, Heike
通讯作者：
Wulff, Heike
影响因子：
5.3
作者：
Chakravarty, S;Herkenham, M
通讯作者：
Herkenham, M