HIV-1 Tat对小鼠脑微血管紧密连接蛋白claudin 5及Aβ转运蛋白的作用研究

Effect of HIV-1 Tat onmouse cerebral microvasculartight junction protein claudin 5 and Aβ transport protein

目的:探讨HIV-1反式转录激活因子(HIV-1 Tat)诱导小鼠脑微血管紧密连接蛋白整合膜蛋白5(claudin 5)及β淀粉样蛋白(Aβ)转运蛋白低密度脂蛋白受体相关蛋白1(LRP-1)、晚期糖基化终产物受体(RAGE)的表达变化及其相互关系。方法:将18只8周龄C57BL/6小鼠随机分成对照组和HIV-1 Tat组,每组9只。对照组静脉注射100μL生理盐水;HIV-1 Tat组静脉注射HIV-1 Tat(100μg/kg)100μL。组织匀浆法测定脑内伊文思蓝(EB)的泄漏量,行蛋白免疫印迹法(WB)及实时荧光定量聚合酶链反应(qPCR)检测小鼠脑微血管claudin 5、LRP-1和RAGE蛋白及mRNA表达。结果:与对照组相比,HIV-1 Tat组小鼠脑EB泄漏量显著增加(P<0.05);小鼠脑微血管claudin 5、LRP-1蛋白和mRNA水平显著下调(P<0.05),RAGE蛋白和mRNA水平上调(P<0.05);claudin 5与LRP-1蛋白水平呈正相关关系(r=0.886,P<0.05),而与RAGE蛋白水平呈负相关关系(r=-0.943,P<0.05)。结论:HIV-1 Tat通过下调claudin 5表达增加BBB通透性,而通过下调LRP-1表达减少Aβ从脑内向血液中转运及上调RAGE表达增加Aβ脑内转运。

Objective: To investigate the HIV-1 trans-activator of transcription(HIV-1 Tat)induced the changes in the expression of mouse cerebral microvascular tight junction protein claudin 5, Aβ transport protein low density lipoprotein receptor-related protein 1(LRP-1) and receptor for advanced glycation endproducts(RAGE)as well as their correlations. Methods: Eighteen 8-week-old C57 BL/6 mice were randomly divided into a control group(n=9) and an HIV-1 Tat group(n=9).100 μL of saline was intravenously injected into mice in the control group;100 μL of HIV-1 Tat(100 μg/kg) was intravenously injected into mice in the HIV-1 Tat group. The tissue homogenate method was used to determine the amount of Evans Blue(EB) leakage in the brain. Western blotting(WB)and real-time fluorescence quantitative polymerase chain reaction(qPCR) were used to detect the protein and mRNA expression of mouse cerebral microvascular claudin 5, LRP-1, and RAGE. Results:Comparedwiththe control group, in the HIV-1 Tat group,the brain EB leakage was increased significantly(P<0.05),the protein and mRNA expression levels of mouse cerebral microvascular claudin 5 and LRP-1 were significantly down-regulated(P<0.05), while RAGE protein and mRNA levels were up-regulated(P<0.05).Claudin 5 was positively correlated with LRP-1 protein level(r=0.886, P<0.05) and negatively correlated with RAGE protein level(r=-0.943, P<0.05). Conclusion: HIV-1 Tat increases BBB permeability by down-regulating claudin 5 expression,reduces Aβ transport from the brain to the blood by down-regulating LRP-1 expression, and increasesintracerebral Aβ transport by up-regulating RAGE expression.