FHF2A and FHF2B in sensory neurons: potential regulators of resurgent currents

感觉神经元中的 FHF2A 和 FHF2B：复苏电流的潜在调节因子

• 批准号: 8837263
• 负责人: Cindy Barbosa Nunez
• 金额: $ 2.69万
• 依托单位: INDIANA UNIV-PURDUE UNIV AT INDIANAPOLIS
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-03-17 至 2017-03-16
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8837263
• 关键词: Action Potentials; Acute; Address; Adverse effects; Afferent Neurons; Antibodies; Binding; Caring; Dependence; Development; Esthesia; Family; Fellowship; Fibroblast Growth Factor; Frequencies; Generations; Health; Knowledge; Measures; Mediating; Medical; Modeling; Molecular; Molecular Profiling; Mutation; National Research Service Awards; Neurons; Pain; Pain Disorder; Pattern; Peripheral; Persistent pain; Physiological; Physiology; Play; Population; Property; Protein Isoforms; Proteins; Research Proposals; Role; Sea Anemones; Sodium; Sodium Channel; Spinal Ganglia; Stimulus; Testing; Therapeutic; Toxin; Variant; base; biophysical properties; inflammatory neuropathic pain; inflammatory pain; novel; novel strategies; overexpression; oxaliplatin; painful neuropathy; prevent; protein expression; public health relevance; therapy development; voltage

 DESCRIPTION (provided by applicant): Pain is one of the most prevalent reasons people in the US seek medical care. Although it is well known that hyperexcitability of dorsal root ganglion (DRG) sensory neurons can contribute to neuropathic and inflammatory pain, the cellular and molecular changes that underlie this hyperexcitability are not fully understood. This lack of knowledge has hindered the development of better therapeutics. One mechanism that clearly contributes to pain is increased electrical activity in DRG containing peripheral sensory neurons. Voltage gated sodium channels (VGSC) contribute to the excitability of sensory neurons, as they are essential for the upstroke of the action potential. A unique type of VGSC current, resurgent current, generates an inward current at repolarizing voltages through an alternate mechanism of inactivation termed open channel block. Resurgent currents are thought to contribute to spontaneous firing, hyperexcitability and the initiation of pain sensations in DRG sensory neurons. Increased resurgent currents in sensory neurons have been implicated in Paroxysmal Extreme Pain Disorder (PEPD), sea-anemone toxin ATX-II induced pain, and oxaliplatin acute- cooling aggravated painful neuropathy. Unfortunately, our understanding of the molecular mechanisms that underlie resurgent currents, especially in DRG neurons, is poor. We propose that Fibroblast Growth Factor Homologous Factors (FHF) 2 that bind the C-terminus of VGSC can substantially modulate resurgent currents in sensory neurons. Specifically, we hypothesize that FHF2A limits resurgent current generation in sensory neurons by mediating long-term inactivation and that FHF2B enhances resurgent currents generation by modulating the voltage dependence of inactivation. Therefore in this NRSA fellowship the applicant will: 1) knockdown FHF2A protein expression and use an antibody targeted to the N-terminus of FHF2A to determine the functional effect on resurgent current generation, 2) overexpress FHF2A to determine if increasing FHF2A activity reduces resurgent currents and 3) knockdown FHF2B protein expression and overexpress FHF2B to determine if modulation this variant enhances resurgent currents. We will also measure endogenous levels of FHF2A and FHF2B in DRG neurons tested for resurgent current to assess correlations between expression profiles and resurgent current properties. The results of this proposal should help us identify novel approaches for the study of hyperexcitability associated with increased resurgent currents, and aid the development of treatments for painful conditions such as PEPD, acute oxaliplatin-induced painful neuropathy and possibly inflammatory pain.

 描述（由申请人提供）：疼痛是美国人寻求医疗护理的最常见原因之一。尽管背根神经节（DRG）感觉神经元的过度兴奋可导致神经病理性疼痛和炎性疼痛是众所周知的，但是作为这种过度兴奋的基础的细胞和分子变化尚未完全理解。这种知识的缺乏阻碍了更好的治疗方法的发展。一种明显导致疼痛的机制是含有外周感觉神经元的DRG中的电活动增加。电压门控钠通道（VGSC）有助于感觉神经元的兴奋性，因为它们对于动作电位的上行是必不可少的。一种独特类型的VGSC电流，复苏电流，通过称为开放通道阻滞的另一种失活机制在复极化电压下产生内向电流。复苏电流被认为有助于DRG感觉神经元的自发放电、过度兴奋和疼痛感觉的起始。感觉神经元中增加的复苏电流与阵发性极端疼痛障碍（PEPD）、海葵毒素ATX-II诱导的疼痛和奥沙利铂急性冷却加重疼痛性神经病有关。不幸的是，我们对复活电流的分子机制的理解，特别是在DRG神经元中，是穷人。我们提出，成纤维细胞生长因子同源性因子（FHF）2，结合VGSC的C-末端，可以大大调节感觉神经元的复苏电流。具体来说，我们假设FHF 2A限制再生电流产生的感觉神经元介导的长期失活和FHF 2B增强再生电流产生的电压依赖性的失活调制。因此，在该NRSA研究中，申请人将：1）敲低FHF 2A蛋白表达并使用靶向FHF 2A N末端的抗体来确定对再生电流产生的功能效应，2）过表达FHF 2A以确定增加FHF 2A活性是否减少再生电流，以及3）敲低FHF 2B蛋白表达并过表达FHF 2B以确定调节该变体是否增强再生电流。我们还将测量用于复苏电流测试的DRG神经元中FHF 2A和FHF 2B的内源性水平，以评估表达谱和复苏电流性质之间的相关性。该提案的结果应有助于我们确定与复活电流增加相关的过度兴奋研究的新方法，并有助于开发疼痛性疾病（如PEPD、急性奥沙利铂诱导的疼痛性神经病变和可能的炎性疼痛）的治疗方法。