Regulation of Kv3.1 by MiRPs in Auditory Neurons

描述(申请人提供)：离子通道是神经元中快速和多样化的电信号的基础，使复杂的生物体能够以高度复杂的方式感知和反应环境、移动、学习、交流和解决问题。在大脑中表达的不同范围的电压门控钾(Kv)电流对于神经元电路中的信号处理和整合是必不可少的。听觉神经元的高频、时间精确放电需要KV3.1形成的钾通道，其特征是快速门控并在相对去极化的电位下激活。KV3.1基因敲除小鼠的听神经元无法跟随高频刺激，高频刺激是人类高频范围内听力损失的模型。对KV3.1电流特性的动态调节被认为是为了调节听神经元对不同刺激频率的放电频率。我们最近发现，KV3.1在哺乳动物脑中与单个跨膜结构域通道辅助亚单位MiRP2形成复合体。此外，MiRP2及其相关亚基mink和miRP1可以改变KV3.1的门控特性，减缓它们的激活和失活，并改变电压依赖性、电流密度和失活。我们现在建议研究MIRP是否与听神经元上的KV3.1通道有关，MIRP是否调控KV3.1的运输，以及MIRP调控KV3.1的哪些方面可能导致听神经元中KV3.1电流的异质性，从而导致宽频听觉知觉。 我们的具体目标是： 1.测定水貂、MiRP1和MiRP2与听神经元KV3.1α亚基形成复合体的能力。 2.测定水貂、MiRP1和MiRP2对动力蛋白依赖的KV3.1α亚基内化的调节能力。 3.采用异源共表达实验和计算机模拟相结合的方法，检验MIRP对Kv3.1、Kv3.3和Kv3.1-Kv3.3通道的MIRP调制在听神经元中的预测效果。

DESCRIPTION (provided by applicant): Ion channels underlie the rapid and diverse electrical signaling in neurons that enables complex organisms to sense and react to their environment, move, learn, communicate and problem-solve in a highly sophisticated manner. The diverse range of voltage-gated potassium (Kv) currents expressed in the brain is essential for signal processing and integration in neuronal circuits. High frequency, temporally precise firing in auditory neurons requires potassium channels formed by Kv3.1, characterized by rapid gating and activation at relatively depolarized potentials. Auditory neurons of Kv3.1 knockout mice are unable to follow high frequency stimulation, a model for hearing loss in the high-frequency range in humans. Dynamic regulation of Kv3.1 current properties is thought to modulate the firing frequency of auditory neurons in response to different stimulus frequencies. We recently found that Kv3.1 forms complexes with MiRP2, a single transmembrane domain channel ancillary subunit, in mammalian brain. Further, MiRP2 and related subunits MinK and MiRP1 modify Kv3.1 gating properties, slowing their activation and deactivation and altering voltage dependence, current density and inactivation. We now propose to investigate whether MiRPs can associate with Kv3.1 channels in auditory neurons, whether MiRPs regulate Kv3.1 trafficking, and which aspects of Kv3.1 regulation by MiRPs could underlie Kv3.1 current heterogeneity in auditory neurons, and thus wide-frequency auditory perception. Our Specific Aims are: 1. Determine the ability of MinK, MiRP1 and MiRP2 to form complexes with Kv3.1 alpha subunits in auditory neurons. 2. Determine the ability of MinK, MiRP1 and MiRP2 to mediate dynamin-dependent internalization of Kv3.1 alpha subunits. 3. Examine the predicted effects in auditory neurons of MiRP modulation of Kv3.1, Kv3.3 and Kv3.1-Kv3.3 channels using a combination of heterologous coexpression experiments and computer simulations.