调控神经发育和再生的ephrinB-EphB受体信号与慢性疼痛：细胞和分子机制的深入研究及小分子干预化合物的筛选

Treating chronic pain, particularly neuropathic pain, is a major challenge for pain scientists and clinicians in the field. The underlying mechanisms of chronic pain remain elusive and methods of treating are very limited. We have recently hypothesized, based on our solid research findings in the past 5-8 years, that ephrinB-EphB receptor signaling, molecules that are important in development of nervous systems and nerve injury and regeneration, play a critical role in the development of chronic pain including the neuropathic pain. Our research have been recently (2008-2011) published in the internationally well recognized core journals including Cancer Research, J Neuroscience, FASEB J, Pain, etc. This proposal is an extension and deep-going of these exciting new concept underlying mechanisms of chronic pain. The major questions include four folds. 1) How do the forward- and reverse signaling of ephrinB-EphB receptor work in development of neuropathic pain? 2) What is the binding site of the extracellular region of EphB1 and NR1 receptor? 3) What is the targeting site of phosphorylation of the intracellular region of EphB1 receptor? 4) Searching for molecules that can reduce neuropathic pain via binding with the ephrinB-EphB receptor signaling. This study will provide new evidence that demonstrate, for the first time, the critical roles of ephrinB-EphB receptor forward- and reverse-signaling in development of neuropathic pain, thus open a new avenue of understanding mechanisms of neuropathic pain. Further, this study will find molecules that could effectively treat chronic pain including the neuropathic pain in laboratory animals with potential in future-patients.

慢性疼痛的治疗是极具挑战的理论和临床课题。其发生发展机制还不清楚，临床缺乏有效的治疗措施。申请人首先提出并论证了一个崭新的假说：神经损伤激活了在神经发育过程中发挥重要作用的蛋白质分子ephrinB-EphB受体信号，这一信号在神经损伤所致的病理性疼痛中起着关键作用。论文发表在Cancer Res, J Neurosci,等国际核心期刊上。本课题是这一研究的继续和深入，将主要解决四个方面的重大问题：（1）ephrinB-EphB受体正向和反向信号通路在慢性疼痛中的作用及机制；（2）EphB1受体胞外段和NR1受体作用的结合位点；（3）EphB1受体胞内段的特异性激活位点；（4）筛选作用于ephrinB-EphB受体信号的特异性小分子化合物。研究成果将在理论上阐明ephrinB-EphB受体信号在慢性疼痛发生发展中的机制；在实际应用上为进一步研究提供独特的工具药和临床药物开发奠定基础。

本项目的系列研究，揭示了ephrinB-EphB1受体信号通路在慢性疼痛, 包含神经病理性、癌性和糖尿病性疼痛中的重要关键作用及其作用机制。初步阐明了EphrinB-EphB受体信号通路活动及其与NMDA受体NR1亚型以及胞内信号转导相关通路的关系；证明了EphrinB-EphB受体信号通路通过胶质细胞的TLR4－白细胞介素机制调控癌性疼痛的发生和发展过程；阐明了EphrinB-EphB与Wnt信号通路在神经病理性疼痛和癌性疼痛发生发展中的重要作用及其相互作用。特别是转录因子YAP/TAZ可能是Wnt和EphrinB-EphB信号通路在细胞核水平的控制总开关，决定了两个信号通路激活后是否可以引起脊髓中枢敏华和痛觉过敏。另外，还发现EphrinB-EphB受体信号在糖尿病性神经病理性疼痛的维持过程中发挥至关重要的作用，但是不参与糖尿病性疼痛的启动诱导过程。这一研究首次指出：糖尿病性疼痛的发生与神经损伤所致病理性疼痛和癌性疼痛有截然不同的机制。在初级感觉神经元水平，EphrinB-EphB受体与NMDAR相互作用，对神经元兴奋性具有显著的调节作用。依据这一思想，我们初步发现一个作用于EphrinB-EphB信号通路的特异性小分子化合物对痛觉的脊髓中枢敏化有非常明显的抑制作用，也有很好的镇痛作用，有望为进一步研发有关镇痛药提供依据和参考、甚至这个小分子本身可能也是一个较好的候选镇痛药。本研究在我们之前初步意见基础上确定了EphrinB-EphB信号路在神经病理性和癌性疼痛发生发展中的重要作用，特别是对疼痛的启动发挥非常关键的作用；论证了有关慢性疼痛发生发展机制的一个崭新的概念：在神经发育过程中发挥重要作用的蛋白质分子EphrinB-EphB受体信号在慢性疼痛中重新被激活进而在疼痛的发生发展中发挥关键作用。这是一个全新的思路和概念，将为最终阐明慢性疼痛的机制和寻找有效的治疗措施提供新的思想和靶标。.