Shaw and Shal voltage-gated potassium channels mediate circadian changes in Drosophila clock neuron excitability
Shaw and Shal voltage-gated potassium channels mediate circadian changes in Drosophila clock neuron excitability
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DOI：
10.1113/jp278826
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发表时间：
2019-11-13
影响因子：
5.5
通讯作者：
Hodge, James J. L.
中科院分区：
文献类型：
--
作者：
Smith, Philip;Buhl, Edgar;Hodge, James J. L.
与哺乳动物一样，果蝇生物钟神经元在白天表现出较高的动作电位放电率和更积极的静息膜电位的活动节律。这种节律性兴奋性已被广泛观察到，但重要的是，它的调节仍未得到解决。我们对侧腹侧时钟神经元 (LNvs) 中这些电活动节律的变化进行了表征和建模。我们发现，由电压门控钾通道 Shaw (Kv3) 和 Shal (Kv4) 介导的电流以昼夜节律方式振荡。显性失活 (DN) 亚基的表达破坏这些通道，会导致昼夜节律运动活动的变化并缩短寿命。 LNv 全细胞记录显示，Shaw 和 Shal 电流的变化驱动动作电位放电率的变化，并且当昼夜节律分子钟停止时，这些节律被废除。使用霍奇金-赫胥黎方程的全细胞生物物理模型可以概括电活动的这些变化。基于该模型，通过使用动态钳直接操纵时钟神经元，我们可以挽救Shaw和Shal的药理阻断，恢复放电节律，从而证明Shaw和Shal的至关重要性。总之，这些发现指出了 Shaw 和 Shal 在控制时钟神经元昼夜节律放电方面的关键作用，并表明时钟神经元电流的变化可以解释这一点。此外，通过动态钳位，我们可以在早晨和晚上的电活动状态之间切换 LNv。我们得出结论，Shaw 和 Shal 的变化是 LNv 发射率每日振荡的基础。
As in mammals, Drosophila circadian clock neurons display rhythms of activity with higher action potential firing rates and more positive resting membrane potentials during the day. This rhythmic excitability has been widely observed but, critically, its regulation remains unresolved. We have characterized and modelled the changes underlying these electrical activity rhythms in the lateral ventral clock neurons (LNvs). We show that currents mediated by the voltage-gated potassium channels Shaw (Kv3) and Shal (Kv4) oscillate in a circadian manner. Disruption of these channels, by expression of dominant negative (DN) subunits, leads to changes in circadian locomotor activity and shortens lifespan. LNv whole-cell recordings then show that changes in Shaw and Shal currents drive changes in action potential firing rate and that these rhythms are abolished when the circadian molecular clock is stopped. A whole-cell biophysical model using Hodgkin-Huxley equations can recapitulate these changes in electrical activity. Based on this model and by using dynamic clamp to manipulate clock neurons directly, we can rescue the pharmacological block of Shaw and Shal, restore the firing rhythm, and thus demonstrate the critical importance of Shaw and Shal. Together, these findings point to a key role for Shaw and Shal in controlling circadian firing of clock neurons and show that changes in clock neuron currents can account for this. Moreover, with dynamic clamp we can switch the LNvs between morning-like and evening-like states of electrical activity. We conclude that changes in Shaw and Shal underlie the daily oscillation in LNv firing rate.