高迁移率族蛋白B1介导内质网应激在脑缺血／再灌注损伤中的作用

The role of high mobility group protein 1 mediated the endoplasmic reticulum stress in cerebral ischemia/ reperfusion injury

目的以“缺血／再灌注-高迁移率族蛋白B1-内质网应激”（I／R—HMGB1-ERS）为切入点，探讨HMGB1参与脑I／R损伤中ERS的机制。方法取出生1～3d乳鼠脑组织，体外培养脑细胞，待细胞传代至第3代用于实验。将细胞分为两组：空白对照组细胞正常培养，不予任何处理；缺氧／复氧组以99．9％氮气培养细胞60min（缺氧），开放瓶口复氧120min模拟I／R模型。利用小干扰RNA（siRNA）沉默HMGB1基因（将siRNA和转染试剂Lipofectamine 2000混合物梯度转染至细胞中）作为HMGB1-siRNA转染组，并设空白对照组（未经任何处理）和阴性对照组（转染对照siRNA）。采用反转录-聚合酶链反应（RT—PCR）和蛋白质免疫印迹试验（Western Blot）检测细胞中HMGB1和ERS相关分子的mRNA及蛋白表达。结果①缺氧／复氧组细胞内HMGB1和ERS相关分子葡萄糖调节蛋白78（GRP78）、C／EBP同源蛋白（CHOP）、天冬氨酸特异性半胱氨酸蛋白酶12（caspase-12）的mRNA及蛋白表达均较空白对照组明显升高（以空白对照组数值为基数1，HMGB1 mRNA：3．19±0．48比1，t=2．183，P=0.008；GRP78 mRNA：2．07±0．33比1，t=3．292，P=0．016；CHOP mRNA：1．93±0．28比1，t=2．573，P=0．021；caspase-12 mRNA：2．42±0．42比1，t=2．261，P=0．027；HMGB1蛋白：2．28±0．36比1，t=2．042，P=0．009；GRP78蛋白：1．33±0．24比1，t=2．781，P=0．016；CHOP蛋白：1．67±0．34比1，t=2．174，P=0．021；caspase-12蛋白：1．36±0．44比1，t=3．192，P=0．008）。说明ERS相关分子参与了细胞缺氧／复氧过程。②siRNA沉默HMGB1基因后，缺氧／复氧模型细胞内HMGB1和ERS相关分子的mRNA及蛋白表达水平均较空白对照组和阴性对照组明显下调（以空白对照组数值为基数1，HMGB1 mRNA：0．27±0．12比1、1．02±0．04，GRP78 mRNA：0．16±0．13比1、0．96±0．04，CHOP mRNA：0．47±0．09比1、0．98±0．07，caspase-12 mRNA：0-31±0．11比1、1．05±0．02；HMGB1蛋白：0．23±0．04比1、1．08±0．01，GRP78蛋白：O．14±0．09比1、1．35±0．03，CHOP蛋白：0．32±0．10比1、0．93±0．06，caspase-12蛋白：0．27±0．09比1、0．97±0．08；P〈0．05或P〈0．01）。说明HMGB1参与ERS的过程可能与GPR78、CHOP、caspase-12等分子有关。结论缺氧，复氧脑细胞内HMGB1和ERS相关分子表达水平均显著上调，而沉默HMGB1基因可明显抑制上述分子的表达水平，“I／R—HMGB1-ERS”路径可能参与脑I／R损伤的发生机制。

Objective To explore the mechanism of high mobility group protein 1 （HMGB1） involved in endoplasmic reticulum stress （ERS） induced by brain ischemia/reperfusion （I/R）, based on I/R-HMGB1-ERS as the breakthrough point. Methods The brain of rats birthed 1-3 days was harvested, and the brain cells were cultured in vitro, which were used in the experiment when the cells were in the third passage. The cells were divided into two groups： cells in blank control group were cultured under the normal conditions without any treatment, and the cells in hypoxia/reoxygenation group were cultured with 99.9% nitrogen for 60 minutes （hypoxia） followed by opening the bottle neck for reoxygenation 120 minutes to simulate I/R model. The HMGB1 gene was silenced by using small interfering RNA （siRNA, siRNA and transfection reagent Lipofectamine 2000 mixture gradient was transfected into the cultured cells） as HMGBI-siRNA transfection group, and blank control （without any treatment） and negative control group （transfected with control siRNA） served as controls. The ＂mRNA and protein expressions of HMGB1 and ERS related molecules were determined by real-time reverse transcription-polymerase chain reaction （RT-PCR） and Western Blot. Results ① In cells of hypoxia/reoxygenation group, the mRNA and protein expressions of HMGB1 and ESR related proteins, including glucose regulating protein 78 （GRP78）, C/EBP homologous protein （CHOP） and caspase-12, were significantly higher than those of blank control group with statistical difference （the value in blank control group was served as baseline 1, HMGB1 mRNA： 3.19±0.48 vs. 1, t = 2.183, P = 0.008; GRP78 mRNA： 2.07 ±0.33 vs. 1, t = 3.292, P = 0.016; CHOP mRNA： 1.93±0.28 vs. 1, t = 2.573, P = 0.021; caspase-12 mRNA： 2.42±0.42 vs. 1, t = 2.261, P = 0.027; HMGB1 protein： 2.28±0.36 vs. 1, t = 2.042, P = 0.009; GRP78 protein： 1.33±0.24 vs. 1, t = 2.781, P = 0.016; CHOP protein： 1.67±0.34 vs. 1, t = 2.174, P = 0.021; caspase-12 protein： 1.36±0.44 vs. 1, t = 3.192, P = 0.008）. It was indicated that ERS related molecules involved in cell hypoxia/reoxygenation process. ② After HMGB1 gene was silenced by siRNA, the cells after hypoxia/reoxygenation showed a decrease in the mRNA and protein expressions of HMGB1 and ERS related moleculars as compared with those of blank control group and negative control group （served the value in blank control group as baseline 1, HMGB1 mRNA： 0.27±0.12 vs. 1, 1.02±0.04; GRP78 mRNA： 0.16±0.13 vs. 1, 0.96±0.04; CHOP mRNA： 0.47 ± 0.09 vs. 1, 0.98± 0.07; easpase-12 mRNA： 0.31±0.11 vs. 1, 1.05 ± 0.02; HMGB 1 protein： 0.23 ± 0.04 vs. 1, 1.08 ± 0.01; GRP78 protein： 0.14 ±0.09 vs. 1, 1.35±0.03; CHOP protein： 0.32±0.10 vs. 1, 0.93±0.06; caspase-12 protein： 0.27±0.09 vs. 1, 0.97±0.08; P 〈 0.05 or P 〈 0.01）. It was indicated that HMGB1 involved in ERS related with GPR7, CHOP, caspase-12. Conclusion Hypoxia/reoxygenation brain intracellular HMGB1 and ERS related molecules expression levels were significantly up-regulated, and silencing HMGB 1 gene can significantly inhibit the expression levels of these molecules, and ＂I/R-HMGB1-ERS＂ pathway may participate in the mechanism of brain I/R injury.