MZF1在TRPV1通路介导的神经病理性疼痛中的作用及其分子机制

Neuropathy pain (NPP), one of serious public health problem , have no proper solution now. Ectopic discharges and alteration of ion channel expression in DRG neurons increases the excitability of the primary sensory neurons，which is an important peripheral mechanism of NPP. TRPV1 was mainly expressed in DRG small neurons, which is up-regulated in neuropathic pain condition,It was known that Kv channels and TRPV1 channels exhibit structural and functional similarities，form a signaling complex in DRG neurons. Our preliminary study found that MZF1 regulated Kv gene transcription and expression in DRG neurons. Nevertheless, it is still not clear that whether MZF1 could regulate the expression of TRPV1, then increase influx of Ca2+ and Na+ and inhibit K+ efflux, and finally affect the depolarization and repolarization process in DRG neurons.The present proposal will use multiple techniques including over-expression or knockdown MZF1 through DRG microinjection, immunohistochemistry, q-PCR, western blot, patch clamp ,chromatin immunoprecipitation assay and pain behavior test to investigate the mechanisms of MZF1 mediated TRPV1 regulation and its role in the development of NPP on a chronic neuropathic pain model induced by chronic constrictive injury (CCI) of the sciatic nerve . it might be hopeful for interventional treatment of NPP through MZF1 gene targets treatment.

神经病理性疼痛（NPP）是重大的公共卫生问题，尚无妥善解决方案。DRG神经元异位放电与离子通道表达变化致初级感觉神经元兴奋性异常，是NPP重要的外周机制。瞬时感受器电位香草酸受体1(TRPV1)主要分布于DRG小神经元，NPP时表达增高，研究证实：TRPV1和电压门控钾离子通道(Kv）的结构和发育过程相似，在DRG可形成信号复合体，我们发现，髓样锌指蛋白1(MZF-1)可调控Kv基因的转录和表达，但MZF-1是否参与TRPV1的转录和表达调控，介导Ca2+、Na+等内流增多，K+离子外流减少，影响DRG神经元的去极化和复极化过程，尚不清楚。本研究拟采用大鼠CCI模型，通过DRG显微注射，过表达和沉默MZF1基因，利用免疫组化、q-PCR、Western blot、膜片钳、染色质免疫共沉淀等技术，研究MZF1在TRPV1通路介导的神经病理性疼痛中的作用及分子机制，为NPP治疗探索新的靶点。

神经病理性疼痛(NP)是临床常见疾病，难以治愈，机制不明。我们既往研究发现，髓样锌指蛋白1(MZF1)可调控电压门控钾离子通道(Kv)的转录和表达参与NP的过程。瞬时感受器电位香草酸受体1(TRPV1)和Kv的结构和发育过程相似，在背根神经节(DRG)内可形成信号复合体，那么MZF1能否通过调控TRPV1表达介导NP的发生与维持，尚不清楚。我们在大鼠坐骨神经慢性压迫损伤模型（CCI）发现，L4/5 DRG中MZF1与TRPV1表达上调。ChIP结果证实，CCI促进MZF1与trpv1启动子区结合。抑制DRG中MZF1表达，可减轻CCI大鼠NP发生和维持阶段痛觉过敏，并下调TRPV1表达。而过表达DRG中MZF1可上调TRPV1表达并诱发正常大鼠痛觉过敏。上述结果证明，DRG中MZF1可通过调控TRPV1表达介导NP的发生与维持。随后我们又进行了MZF1在慢性炎性痛中的作用及机制研究。基质金属蛋白酶(MMPs)作为一类锌离子依赖性内肽酶可通过降解细胞外基质参与多种慢性疼痛的过程。其中，MMP-2/9在慢性炎性痛中发挥重要作用。另有研究证实MZF1通过调控MMP-2的表达抑制宫颈癌细胞的迁移和分化。但是，MZF1能否调控MMP-2/9的表达参与慢性炎性痛的发生和维持，目前尚无报道。通过足底皮下注射完全弗氏佐剂（CFA）制备慢性炎性痛模型，我们发现CFA诱发大鼠发生痛觉过敏及L4/5 DRG中MZF1和MMP-2/9表达上调。ChIP结果表明，CFA促进DRG中MZF1与mmp2/9启动子区结合。沉默DRG中MZF1可减轻慢性炎性痛的发生和维持阶段痛觉过敏，并下调MMP-2/9的表达。综上，MZF1可通过调控MMP-2/9表达参与慢性炎性痛的发生与维持阶段。上述两项研究提示通过DRG靶向治疗MZF1可能为临床上治疗慢性疼痛提供了新的靶点和思路。