敲低mGluR5通过激活PI3K/AKT信号通路减轻阿尔茨海默病相关病变  

mGluR5 knockdown attenuates Alzheimer disease-related pathology by activating PI3K/AKT signaling pathway

作　　者：魏雪敏 陈秋旋 陈玉钊 张一霖 吴美建 张珂珂 魏伟[1] WEI Xue-min;CHEN Qiu-xuan;CHEN Yu-zhao;ZHANG Yi-lin;WU Mei-jian;ZHANG Ke-ke;WEI Wei(Department of Pathophysiology,School of Medicine,Laboratory of Pathophysiology,National Administration of Tradi-tional Chinese Medicine,Jinan University,Guangzhou 510632,China;Translational Medicine Center,The Second Affili-ated Hospital,Guangzhou Medical University,Guangzhou 510260,China)

机构地区：[1]暨南大学基础医学与公共卫生学院病理生理学系,国家中医药管理局病理生理科研实验室,广东广州510632 [2]广州医科大学附属第二医院转化医学中心,广东广州510260

出　　处：《中国病理生理杂志》2022年第6期961-969,共9页Chinese Journal of Pathophysiology

基　　金：国家自然科学基金资助项目(No.81100944);广东省自然科学基金资助项目(No.2018A030313565);广州市科技计划项目(No.201904010040)。

摘　　要：目的:探讨敲低代谢型谷氨酸受体5(metabotropic gultamate receptor 5,mGluR5)对6月龄5xFAD小鼠β-淀粉样蛋白(amyloidβ-protein,Aβ)病变、突触结构和神经炎症的影响及其潜在机制。方法:选取2、6和12月龄的野生型(wild-type,WT)和5xFAD小鼠,用Western blot检测不同阶段小鼠海马组织中mGluR5蛋白的表达情况。取6月龄的WT、5xFAD、mGluR5^(+/-)和5xFAD/mGluR5^(+/-)小鼠脑组织,免疫荧光染色检测Aβ斑块的聚集,Western blot检测海马组织中淀粉样前体蛋白(amyloid precursor protein,APP)和p-APP蛋白水平,海马组织透射电子显微镜观察突触的超微结构,Western blot检测海马组织中突触蛋白、炎症因子和mGluR5下游磷脂酰肌醇3-激酶(phosphati⁃dylinositol 3-kinase,PI3K)/AKT信号通路相关蛋白的表达。结果:(1)随着月龄的增加,5xFAD小鼠海马组织中mGluR5的表达显著增加(P<0.01);(2)敲低mGluR5减少了5xFAD小鼠海马区Aβ斑块,降低了APP和p-APP蛋白水平(P<0.05);(3)敲低mGluR5减轻了5xFAD小鼠海马的突触结构损伤,5xFAD/mGluR5^(+/-)小鼠突触前标志物突触小泡蛋白(synaptophysin,SYP)和突触后标志物突触后致密蛋白95(postsynaptic density protein 95,PSD95)表达显著高于5xFAD小鼠(P<0.05),而树突标志物微管相关蛋白2(microtubule-associated protein 2,MAP2)和神经元标志物神经元核抗原(neuronal nuclear antigen,NeuN)表达无显著差异;(4)敲低mGluR5可降低5xFAD小鼠的神经炎症反应,减少炎症因子的释放;(5)5xFAD小鼠敲低mGluR5可通过激活PI3K/AKT信号通路发挥神经保护作用,还通过抑制糖原合成酶激酶3β(glycogen synthetase kinase-3β,GSK-3β)/κB抑制因子激酶(inhibitor ofκB kinase,IKK)/核因子κB(nuclear factor-κB,NF-κB)炎症信号通路减轻神经炎症反应。结论:敲低mGluR5可以减轻6月龄5xFAD小鼠的Aβ病变、突触结构损伤和神经炎症,其机制可能与PI3K/AKT及其下游GSK-3β/IKK/NF-κB信号通路有关。AIM:To explore the effects of metabotropic glutamate receptor 5(mGluR5)knockdown on amy⁃loidβ-protein(Aβ)pathology,synaptic structure and neuroinflammation in 6-month-old 5xFAD mice and its underlying mechanism.METHODS:Wild-type(WT)and 5xFAD mice aged 2,6 and 12 months were selected to detect the expres⁃sion of mGluR5 protein in the hippocampus by Western blot.Six-month-old WT,5xFAD,mGluR5^(+/-)and 5xFAD/mGluR5^(+/-)mice were selected to explore the role of mGluR5 in Alzheimer disease-related pathology.The expression and aggregation of Aβplaques were detected by immunofluorescence.The protein levels of amyloid precursor protein(APP)and p-APP in hippocampus were detected by Western blot.The ultrastructure of the synapse was observed by transmission electron microscopy.The expression levels of synaptic proteins,inflammatory factors and phosphatidylinositol 3-kinase(PI3K)/AKT signaling pathway-related proteins in hippocampus were detected by Western blot.RESULTS:(1)The ex⁃pression of mGluR5 in the hippocampus of 5xFAD mice increased with age(P<0.01).(2)Knockdown of mGluR5 re⁃duced Aβplaques(P<0.01),and decreased the protein levels of APP and p-APP in the hippocampus of 5xFAD mice(P<0.05).(3)Knockdown of mGluR5 attenuated synaptic structural damage in the hippocampus of 5xFAD mice.The expres⁃sion levels of presynaptic marker synaptophysin(SYP)and postsynaptic marker postsynaptic density protein 95(PSD95)in 5xFAD/mGluR5^(+/-)mice were significantly higher than those in 5xFAD mice(P<0.05),while the expression of dendritic marker microtubule-associated protein 2(MAP2)and neuron marker neuronal nuclear antigen(NeuN)had no statistically significant difference.(4)Knockdown of mGluR5 reduced neuroinflammation in 5xFAD mice.(5)Knockdown of mGluR5 in 5xFAD mice exerted neuroprotective effect by activating PI3K/AKT signaling pathway,and reduced neuroin⁃flammation by inhibiting glycogen synthetase kinase-3β(GSK-3β)/inhibitor ofκB kinase(IKK)/nuclear factor-κB(NF-κB)signaling pathway.CONCLUSION:Knockdown of

关 键 词：阿尔茨海默病 代谢型谷氨酸受体5 Β-淀粉样蛋白 神经炎症 突触 

分 类 号：R749.16[医药卫生—神经病学与精神病学] R363[医药卫生—临床医学]