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目的探讨炎症诱导胆固醇调节元件结合蛋白裂解激活蛋白(sterol regulatory element binding proteins cleavage-activating protein,SCAP)功能失调促进ApoE~(-/-)小鼠动脉粥样硬化形成的分子机制。方法 24只8周龄雄性ApoE~(-/-)小鼠(C57BL/6遗传背景,体质量18~24 g)随机分组为高胆固醇饮食组(n=12,对照组)和高胆固醇饮食+炎症组(n=12,炎症组)。炎症组小鼠给予隔日皮下注射10%酪蛋白,非炎症组小鼠给予隔日皮下注射生理盐水,共14周。双抗夹心ELISA法检测ApoE~(-/-)小鼠血清炎症指标(serum amyloid A,SAA)和TNF-α水平,HE染色观察ApoE~(-/-)小鼠主动脉结构及局部炎症细胞浸润情况,油红O染色观察ApoE~(-/-)小鼠主动脉斑块形成情况,Real-time PCR法与免疫组织化学法检测ApoE~(-/-)小鼠主动脉LDLr、SREBP2、SCAP、α-甘露糖苷酶Ⅰ及α-甘露糖苷酶ⅡmRNA与蛋白表达。结果炎症组小鼠血清SAA[(529±23)ng/m L]与TNF-α[(37 900±3 100)ng/m L]水平显著高于对照组小鼠血清SAA[(248±27)ng/m L]与TNF-α[(1 789±219)ng/m L]水平(P<0.01),表明ApoE~(-/-)小鼠炎症模型建立成功。炎症组小鼠较对照组小鼠主动脉粥样硬化性病变更为严重(P<0.01),其LDLr、SCAP及α-甘露糖苷酶ⅡmRNA及蛋白表达、细胞核内NSREBP2水平明显高于对照组(P<0.05)。结论炎症通过增加血管壁细胞内胆固醇敏感器SCAP的表达,并通过增强高尔基体α-甘露糖苷酶Ⅱ对SCAP的糖基化修饰,促进ApoE~(-/-)小鼠动脉粥样硬化的发生和发展。
Objective To investigate the molecular mechanism of inflammation-induced sterol regulatory element binding proteins cleavage-activating protein (SCAP) dysfunction in atherosclerosis in ApoE ~ (- / -) mice. Methods Twenty - four male ApoE ~ (- / -) mice of 8 weeks old (C57BL / 6 genetic background, body weight 18-24 g) were randomly divided into high cholesterol diet group (n = 12) and high cholesterol diet + Inflammation group (n = 12, inflammation group). Inflammation mice were given subcutaneous injection of 10% casein on alternate days. Non-inflamed mice were injected subcutaneously with normal saline every other day for 14 weeks. The levels of serum amyloid A (SAA) and TNF-α in ApoE ~ (- / -) mice were detected by double-antibody sandwich ELISA. The aorta structure and local inflammatory cells in ApoE ~ (- Infiltration and oil red O staining were used to observe the formation of aortic plaque in ApoE ~ (- / -) mice. Real-time PCR and immunohistochemistry were used to detect the expression of LDLr and SREBP2 in ApoE ~ (- SCAP, α-mannosidase Ⅰ and α-mannosidase Ⅱ mRNA and protein expression. Results Serum levels of SAA (529 ± 23) ng / m L and TNF-α [(37 900 ± 3 100) ng / m L] in the inflammation group were significantly higher than those in the control group ) ng / m L] and TNF-α [(1789 ± 219) ng / m L] (P <0.01), indicating that the inflammatory model of ApoE ~ (- / -) mice was established successfully. Compared with the control group, mice in the inflammation group showed more severe aortic atherosclerosis (P <0.01). The expression of LDLr, SCAP, α-mannosidase Ⅱ mRNA and protein and the level of NSREBP2 in the nucleus were significantly higher than those in the control group <0.05). Conclusion Inflammation can promote the development of atherosclerosis in ApoE ~ (- / -) mice by increasing the expression of intracellular cholesterol sensor SCAP and enhancing the glycosylation of SCAP by Golgi α-mannosidase Ⅱ And development.