New Kv7 modulators to stop sensitized overexcitation of neurons - Summary This R21 aims to create a robust empirical basis for the development of pain therapies by targeting the regulation of neuronal Kv7 channels. In the US, approximately 50 million adults suffer from chronic pain, and 17 million peoples experience high-impact chronic pain. Neuronal Kv7 channels are a class of low-voltage gated potassium channels that generate the M-currents, which counteract generating action potentials at or near the resting potential. M-current suppression induced by some inflammatory mediators and neurotransmitters transiently increases neuronal excitability and exacerbates pain. Thus, preventing M-current suppression may provide a potent novel approach to mitigate sensitized pain. In fact, our prior study using mutant Kv7.2 knock-in mice, which showed reduced M-current suppression, demonstrated a reduction in inflammatory pain. Based on this insight, we developed a novel in silico screening process identifying compounds that enhance stability of binding between Kv7 channels and the essential co-factor phosphatidyl- inositol 4,5-bisphosphate (PIP2), which plays a critical role for M-current suppression. Aligned with this idea, we have identified that the endogenous hormone DHEAS attenuates M-current suppression and mitigates inflammatory pain. In addition, our very recent preliminary study has indicated some Kv7 modulators of this class caused a hyperpolarizing shift of activation voltage in addition to attenuation of receptor-induced Kv7.2 current suppression. This R21 investigates the overall hypothesis that a new type of Kv7 channel modifiers, which stabilizes the Kv7-PIP2 conformation, can effectively alleviate pain. We will test our hypothesis by two cohesive aims. Aim 1-1 will utilize a novel screening process to identify potent compounds for this class of Kv7 modifiers. Aim 1-2 will functionally verify candidate compounds by electrophysiological experiments for attenuation of Kv7/M-current suppression and change in activation voltage. Aim1-3 focuses on identifying crucial interactions that mediate the pharmacological effects by combining mutation analysis and computational simulation. Aim 2 will evaluate the behavioral impacts of new Kv7 modulators identified in Aim 1 on mice, including sedation and pain responses. This R21 is entirely innovative because no drugs have been developed to this drug binding site in the Kv7 channel. This mechanism of action will overcome the limitation of existing Kv7 channel openers. We believe that this R21 is important both biologically and clinically because data obtained will not only establish the foundation for a novel class of Kv7 channel modifiers but also provide insights into their therapeutic potentials for chronic pain.
