Regulation of Kv3.1 by MiRPs in Auditory Neurons

描述（由申请人提供）：离子通道是神经元中快速和多样化电信号的基础，使复杂生物体能够以高度复杂的方式感知和对环境做出反应，移动，学习，交流和解决问题。在大脑中表达的电压门控钾（Kv）电流的不同范围对于信号处理和神经元电路的整合是必不可少的。听觉神经元的高频、短时精确放电需要Kv3.1形成的钾通道，其特征是快速门控和在相对去极化电位下激活。Kv3.1基因敲除小鼠的听觉神经元无法跟随高频刺激，这是人类高频范围听力损失的一个模型。Kv3.1电流特性的动态调节被认为可以调节听觉神经元在不同刺激频率下的放电频率。我们最近发现，在哺乳动物大脑中，Kv3.1与MiRP2形成复合物，MiRP2是一种单一的跨膜结构域通道辅助亚基。此外，MiRP2和相关亚基MinK和MiRP1修饰Kv3.1的门控特性，减缓它们的激活和失活，改变电压依赖性、电流密度和失活。我们现在提议研究MiRPs是否与听觉神经元中的Kv3.1通道相关，MiRPs是否调节Kv3.1的运输，以及MiRPs调节Kv3.1的哪些方面可能是听觉神经元中Kv3.1电流异质性的基础，从而导致宽频听觉感知。

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.