Activated ephrinA3/EphA4 forward signaling induces retinal ganglion cell apoptosis in experimental glaucoma
Activated ephrinA3/EphA4 forward signaling induces retinal ganglion cell apoptosis in experimental glaucoma
复制标题
激活的 ephrinA3/EphA4 前向信号诱导实验性青光眼视网膜神经节细胞凋亡
DOI：
10.1016/j.neuropharm.2020.108228
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发表时间：
2020-11-01
影响因子：
4.7
通讯作者：
Wang，Zhongfeng
中科院分区：
文献类型：
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作者：
Xu，Lin-Jie;Gao，Feng;Wang，Zhongfeng
已有研究表明EphA4参与神经元损伤，并且ephrinA3与EphA4之间存在较强的相互作用。在本研究中，我们发现在大鼠慢性高眼压（COH）实验性青光眼模型中，视网膜细胞包括视网膜神经节细胞（RGCs）和网膜ller细胞中EphA4和ephrinA3蛋白的表达增加，这可能导致RGCs上ephrinA3/EphA4正向信号激活，p-EphA4/EphA4比值升高。玻璃体内注射ephrinA3-Fc （EphA4的激活剂），模拟COH对p-EphA4/EphA4的影响，诱导正常视网膜中tunel阳性信号增加，并伴有RGCs的树突脊柱收缩和更薄的树突。此外，玻璃体内注射ephrinA3-Fc增加磷酸化src和GluA2的水平（p-src和p-GluA2）。共免疫沉淀实验显示EphA4、p-src和GluA2之间存在相互作用。玻璃体内注射ephrinA3-Fc可降低正常视网膜细胞表面GluA2蛋白的表达，而玻璃体内注射src家族酪氨酸激酶抑制剂PP2可阻止这种表达。预注射PP2或Ca2+渗透性glua2缺乏AMPA受体抑制剂Naspm显著和部分减少了ephrina3 - fc注射和COH视网膜中tunel阳性rgc的数量。我们的研究结果表明，活化的ephrinA3/EphA4正向信号通路促进了GluA2的内吞作用，导致RGC的树突脊柱内缩，从而促进了COH大鼠RGC的凋亡。适当降低ephrinA/EphA信号强度可能是防止青光眼RGCs丢失的有效途径。
Previous studies have demonstrated that EphA4 participates in neuronal injury, and there is a strong interaction between ephrinA3 and EphA4. In this study, we showed that in a rat chronic ocular hypertension (COH) experimental glaucoma model, expression of EphA4 and ephrinA3 proteins was increased in retinal cells, including retinal ganglion cells (RGCs) and Müller cells, which may result in ephrinA3/EphA4 forward signaling activation on RGCs, as evidenced by increased p-EphA4/EphA4 ratio. Intravitreal injection of ephrinA3-Fc, an activator of EphA4, mimicked the effect of COH on p-EphA4/EphA4 and induced an increase in TUNEL-positive signals in normal retinas, which was accompanied by dendritic spine retraction and thinner dendrites in RGCs. Furthermore, Intravitreal injection of ephrinA3-Fc increased the levels of phosphorylated src and GluA2 (p-src and p-GluA2). Co-immunoprecipitation assay demonstrated interactions between EphA4, p-src and GluA2. Intravitreal injection of ephrinA3-Fc reduced the expression of GluA2 proteins on the surface of normal retinal cells, which was prevented by intravitreal injection of PP2, an inhibitor of src-family tyrosine kinases. Pre-injection of PP2 or the Ca2+-permeable GluA2-lacking AMPA receptor inhibitor Naspm significantly and partially reduced the number of TUNEL-positive RGCs in the ephrinA3-Fc-injected and COH retinas. Our results suggest that activated ephrinA3/EphA4 forward signaling promoted GluA2 endocytosis, then resulted in dendritic spine retraction of RGCs, thus contributing to RGC apoptosis in COH rats. Attenuation of the strength of ephrinA/EphA signaling in an appropriate manner may be an effective way for preventing the loss of RGCs in glaucoma.