mGluR I诱导Kir通道下调参与视网膜Müller胶质细胞激活的分子机制研究

Gliosis is a common feature in the pathological alternations of the injuries and diseases of central nervous system (including retina). Reactivated glia may play a two-edged role, protecting the tissue from further damage and contributing to neurodegeneration. Therefore, the study on the mechanisms underlying glial cell gliosis is very important for understanding the neuronal injury mechanisms and the neuronal regeneration and remodeling. Glaucoma, the second leading cause of blindness worldwide, is a neurodegenerative disease characterized by apoptotic death of retinal ganglion cells and progressive visual field loss, which is often associated with high intraocular pressure (IOP). Our previous studies demonstrated that over-activation of mGluR I in retinal Müller cells by excessive extracellular glutamate in chronic ocular hypertension (COH) rats induced a downregulation of Kir currents, thus resulting in elevated expression of GFAP and contributing to Müller cell gliosis. Based on our previous findings, in the present project, we want to further explore the molecular mechanisms of Kir channel trafficking and the intracellular signaling pathways mediating the elevation of GFAP expression in the mGluR I induced Müller cell gliosis in a rat COH model and purified cultured Müller cells by using patch-clamp electrophysiological recordings, immunohistochemistry/immunocytochemistry, Western blot and molecular biology techniques. We also aimed to explore the possible pathways for inhibiting Müller cell gliosis and preventing retinal ganglion cell from glaucomatous injury.

胶质细胞激活是神经系统(包括视网膜)损伤和疾病病理过程中的共同特征，激活的胶质细胞发挥神经保护和加重神经损伤的双重作用。研究胶质细胞的激活机制，对理解神经细胞损伤的机制和神经再生、修复具有重要的意义。青光眼是位居第二的不可逆性神经致盲眼病，眼内压增高是其最重要的致病因素之一。我们先前的研究发现，在慢性高眼压青光眼大鼠模型，胞外过量聚集的谷氨酸作用于视网膜Müller胶质细胞的mGluR I受体，下调Kir通道电流，导致GFAP表达上调，即Müller细胞激活。本课题拟在慢性高眼压大鼠模型和纯化培养的Müller细胞，利用膜片钳电生理、免疫组织(细胞)化学、Western blot和分子生物学等多种技术，进一步深入研究mGluR I诱导Müller细胞激活过程中Kir通道trafficking的分子机制及GFAP表达上调的信号通路，探讨抑制Müller细胞激活，以及神经节细胞保护的可能途径。

胶质细胞激活是神经系统(包括视网膜)损伤和疾病病理过程中的共同特征，激活的胶质细胞发挥神经保护和加重神经损伤的双重作用，研究胶质细胞的激活机制，对理解神经细胞损伤的机制和神经再生、修复具有重要的意义。我们发现，用mGluR I特异的激动剂DHPG处理纯化培养的大鼠视网膜Müller细胞，导致Müller细胞Kir4.1蛋白的合成减少，并导致Kir4.1通道下膜；MEK/ERK-p38/CREB/c-fos信号通路参与Kir通道抑制诱导的视网膜Müller细胞GFAP表达上调；在编码Kir4.1的kcnj10基因上参与诱导Kir4.1下调的功能位点可能是Tyr9和Ser370。这些结果揭示了青光眼Müller细胞激活的分子机制，为有效抑制Müller细胞，进而减轻青光眼视网膜神经节细胞凋亡策略的制定奠定了基础。全面完成了预期目标，发表标注基金资助的论文7篇，其中SCI论文6篇。