Regulation and Function of PlexinA2 Forward Signaling in Persistent Pain

PlexinA2 正向信号在持续性疼痛中的调节和功能

• 批准号: 10669302
• 负责人: Kimberly Stephens
• 金额: $ 30.24万
• 依托单位: ARKANSAS CHILDREN'S HOSPITAL RES INST
• 依托单位国家: 美国
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-07-11 至 2027-06-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10669302
• 关键词: Action Potentials; Affect; Afferent Neurons; Axon; Binding; Cell model; Centers of Research Excellence; Childhood; Chromatin; Chronic; Collection; Complex; Cues; Development; Disease; Distal; Doctor of Philosophy; Elderly; Environment; Epigenetic Process; Family; Gene Expression; Gene Expression Regulation; Genes; Genetic Transcription; Health; Heterodimerization; In Vitro; Individual; Inflammation; Intrathecal Injections; Life; Ligation; Maps; Measures; Modeling; Morphology; Motor; Neurites; Neuroglia; Neurons; Nociception; Nociceptors; Nucleic Acid Regulatory Sequences; Outcome; Pain; Pathway interactions; Pediatric Research; Peripheral Nervous System; Peripheral nerve injury; Persistent pain; Phenotype; Play; Population; Predisposition; Prevention; Process; Proteomics; Refractory; Regulation; Research Project Grants; Resources; Role; Semaphorins; Sensory; Signal Transduction; Spinal Cord; Spinal Ganglia; Stimulus; Structure; Study models; Testing; axon guidance; cell type; chronic pain; differential expression; early life stress; epigenetic regulation; epigenomics; in vivo; in vivo Model; inflammatory pain; knock-down; member; multiple omics; nerve injury; neural; neuron development; neuronal cell body; overexpression; pain behavior; painful neuropathy; plexin; proteogenomics; receptor; receptor binding; regenerative; sciatic nerve; surgical pain; therapeutic target; transcription factor; transcriptome sequencing

Summary Persistent pain develops following nerve injury when primary sensory neurons show complex, activity- dependent plasticity and ectopic discharges. It is often refractory to existing treatments and associated with adverse health outcomes. The dorsal root ganglion (DRG) is a collection of several types of sensory neuronal cell bodies and satellite glia which acts as the initial point of modulation of action potentials from potentially noxious stimuli to second order spinal cord neurons. Epigenetic variability is known to cause dysregulation of gene transcription which may modulate nociception to alter an individual’s susceptibility for persistent pain. Chromatin accessibility regulates transcription factor binding to cis-regulatory regions and subsequent changes in gene expression. Therefore, understanding how changes in chromatin accessibility at these regulatory regions modulate transcription factor binding in chronic pain states would help to identify regulatory loci in the DRG. Following peripheral nerve injury, regenerative mechanisms are activated to recover lost motor, sensory, and autonomic functions. Neuropathic pain develops when these mechanisms promote maladaptive neural connectivity that becomes electrically hyperexcitable and generates spontaneous and evoked action potentials. How these processes become activated to promote pain in the absence of nerve injury is unknown. We have completed the first comprehensive map of changes in chromatin accessibility with matching RNA- seq in the DRG using two well-studied models of persistent pain – surgical ligation of the sciatic nerve (CCI) and hind paw inflammation (CFA). We identified differential expression of members of the plexin-semaphorin pathway with changes in chromatin accessibility at their putative cis-regulatory regions. This pathway generates attractive or repulsive cues to reunite with its distal, denervated segment. PlexinA2 is a member of a large family of receptors that bind to semaphorin, which then heterodimerizes with Nrp1 to form a functional neuronal receptor that activates Rnd1. The role of PlexinA2, Nrp1 and Rnd1 in persistent pain remains unclear. However, altered Plxna2 expression during development disrupts normal peripheral nervous system morphology. We hypothesize that altered epigenetic regulation of Plxna2, Nrp1 and Rnd1 expression in sensory neurons plays a functional role in axon guidance and promotes persistent pain states. In addition, we hypothesize that changes to the sensory environment during neuronal development may epigenetically prime nociceptors to promote altered nociceptive thresholds later in life. We will pursue the following Specific Aims to test our hypotheses: (1) To determine how chromatin topology affects Plxna2 expression and genes involved in its forward signaling in DRG neurons in neuropathic and inflammatory pain conditions, (2) To understand how modulation of the Plxna2-Nrp1- Rnd1 axis in DRG neurons alters neurite structure and pain behaviors, (3) To determine the effects of early-life stress on Plxna2 signaling in the dorsal root ganglion following nerve injury in later life.

总结 当初级感觉神经元表现出复杂的活动时，神经损伤后会产生持续性疼痛- 依赖性可塑性和异位放电。它通常对现有的治疗是难治的，并且与 不良健康后果。背根神经节（DRG）是一个集合的几种类型的感觉神经元 细胞体和卫星神经胶质细胞，作为潜在的动作电位调制的起始点， 脊髓二级神经元的伤害性刺激。已知表观遗传变异性会导致 可能调节伤害感受以改变个体对持续性疼痛的易感性的基因转录。 染色质可及性调节转录因子与顺式调控区的结合及随后的变化 in gene基因expression表达.因此，了解这些调控区域的染色质可及性的变化 在慢性疼痛状态中调节转录因子结合将有助于鉴定DRG中的调节位点。 在周围神经损伤后，再生机制被激活以恢复失去的运动、感觉和神经功能。 自主功能当这些机制促进适应不良的神经 连接变得电超兴奋并产生自发和诱发的动作电位。 在没有神经损伤的情况下，这些过程如何被激活以促进疼痛尚不清楚。 我们已经完成了第一个全面的染色质可及性变化与匹配RNA的地图- 使用两种充分研究的持续性疼痛模型-坐骨神经手术结扎（CCI）和 后爪炎症（CFA）。我们确定了丛蛋白-信号蛋白成员的差异表达， 在其推定的顺式调节区域的染色质可及性的变化的途径。这种途径产生 吸引或排斥的线索与其远端去神经节团聚。丛蛋白A2是一个大家族的成员 与脑信号蛋白结合的受体，然后与Nrp 1异源二聚化形成功能性神经元受体 激活Rnd 1。PlexinA 2、Nrp 1和Rnd 1在持续性疼痛中的作用尚不清楚。然而，改变 plxna 2在发育过程中的表达破坏了正常的周围神经系统形态。我们假设 感觉神经元中Plxna 2、Nrp 1和Rnd 1表达的表观遗传调节改变在感觉神经元中起着功能性作用， 在轴突引导中的作用，并促进持续性疼痛状态。此外，我们假设， 神经元发育过程中的感觉环境可能在表观遗传学上引发伤害感受器， 伤害性阈值的变化我们将追求以下具体目标来验证我们的假设：（1） 确定染色质拓扑结构如何影响Plxna 2表达和参与DRG正向信号传导的基因 神经病理性和炎症性疼痛条件下的神经元，（2）为了了解Plxna 2-Nrp 1- DRG神经元Rnd 1轴改变神经突起结构和痛行为。（3）研究早期生活对大鼠痛行为的影响 在以后的生活中神经损伤后背根神经节中对Plxna 2信号传导的应激。