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流行病学数据显示,急性心肌梗死仍然是当前世界上主要的致死性疾病之一。及时的血管内溶栓和支架成形术等再灌注手段来开通罪犯血管对于缓解心肌缺血、减少梗死面积是非常重要的[1]。然而,过往有研究[2]表明冠脉再通后的再灌注过程可引起缺血区域心肌细胞的二次打击,这种现象被称为“缺血/再灌注损伤”。因此,对于急性心肌梗死的治疗而言,缓解缺血/再灌注损伤是必不可少的[3]。
研究[4]显示,缺血/再灌注损伤的发生发展与多种病理生理机制有关,内质网应激在其中发挥着重要作用。内质网应激相关通路活化可诱导下游的凋亡途径激活,进而促进心肌组织中的缺血/再灌注损伤进展[5-6]。以往研究[7-8]证实心肌细胞在缺血再灌注环境中高表达内质网应激相关的信号蛋白,如活化转录因子6(ATF6)、C/EBP同源蛋白(CHOP)、葡萄糖调节蛋白78(GRP78)等,且抑制内质网应激信号转导可有效降低细胞凋亡率。
在生理条件下,Nrf2通过与Keap1结合而锚定于胞质中。一旦受到应激作用,Nrf2与Keap1分离,转入核内并调控下游靶基因如HO-1的表达,它们可显著抑制细胞内凋亡级联反应的活化[9-10]。有研究[11]表明,Nrf2/HO-1通路表达上调对缺血再灌注环境中的心肌细胞有明显的保护作用,但是其中的潜在机制尚未完全阐明。本研究探讨Nrf2/HO-1抗心肌缺血再灌注损伤的可能机制。
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cTnⅠ和α-横纹肌肌动蛋白均在所提取的细胞中高表达(见图 1)。Nrf-2 rAAV9和HO-1 rAAV9处理细胞后,胞内Nrf-2和HO-1 mRNA表达量上升(P < 0.01和P < 0.05);HO-1 siRNA处理细胞后,胞内HO-1 mRNA表达量下调(P < 0.05)(见表 1)。
分组 n Nrf2 mRNA HO-1 mRNA 对照组 3 0.95±0.04 1.04±0.05 过表达组 3 2.63±0.44 3.25±0.31* 沉默组 3 — 0.38±0.08* F — 6.59△ 193.67 P — < 0.01 < 0.01 MS组内 — — 0.035 △示t′值; q检验: 与对照组比较*P < 0.05 表 1 各组目的基因表达情况(x±s)
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Nrf2或HO-1高表达可抑制缺氧/复氧诱导的心肌细胞活性的下降(P < 0.05);HO-1基因沉默后,Nrf2过表达对心肌细胞活性无明显影响(P>0.05)(见表 2)。
分组 n OD值 F P MS组内 对照组 5 1.01±0.09 27.75 < 0.01 0.007 模型组 5 0.51±0.09* Nrf2过表达组 5 0.71±0.06*# HO-1过表达组 5 0.72±0.08*# HO-1沉默+Nrf2过表达组 5 0.56±0.09*▲△ q检验: 与对照组比较*P < 0.05;与模型组比较#P < 0.05;与Nrf2过表达组比较▲P < 0.05;与HO-1过表达组比较△P < 0.05 表 2 各组心肌细胞活性比较(x±s)
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TUNEL染色结果显示,缺氧/复氧组心肌细胞凋亡率高于对照组(P < 0.05),Nrf2或HO-1过表达可有效抑制缺氧/复氧处理诱导的细胞凋亡(P < 0.05),HO-1表达下调减弱了Nrf2上调的抗凋亡效果(P < 0.05)(见图 2、表 3)。Nrf2或HO-1过表达降低了缺氧/复氧引起的心肌细胞cTnⅠ及CK-MB释放量(P < 0.05)(见表 3)。
分组 n 细胞凋亡率/% cTnⅠ /(pg/mL) CK-MB /(U/L) 对照组 4 10.13±3.11 42.98±13.52 20.89±11.06 模型组 4 59.78±9.16* 452.30± 47.44* 93.16±7.56* Nrf2过表达组 4 41.78±4.1*# 344.50±52.93*# 64.94±13.80*# HO-1过表达组 4 40.21±4.98*# 312.20±46.07*# 61.52±9.05*# HO-1沉默+Nrf2过表达组 4 58.15±8.01*▲△ 450.00± 43.69*▲△ 89.14±8.06*▲△ F — 40.03 45.05 24.16 P — < 0.01 < 0.01 < 0.01 MS组内 — 39.870 2 022.489 103.321 q检验: 与对照组比较*P < 0.05;与模型组比较#P < 0.05;与Nrf2过表达组比较▲P < 0.05;与HO-1过表达组比较△P < 0.05 表 3 各组细胞凋亡率及细胞培养上清中cTnⅠ和CK-MB含量比较(x±s)
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缺氧/复氧组心肌细胞的GRP78和ATF6的mRNA表达量高于对照组(P < 0.05);Nrf2或HO-1过表达降低了GRP78和ATF6的表达量(P < 0.05);当HO-1表达受抑时,Nrf2过表达对缺氧/复氧诱导的GRP78和ATF6表达无明显影响(P>0.05);Nrf2或HO-1过表达可抑制缺氧/复氧诱导的CHOP及Caspase-3表达(P < 0.05)(见表 4)。
分组 n GRP78 ATF6 CHOP Caspase-3 对照组 3 1.06±0.21 0.98±0.12 1.11±0.14 1.09±0.20 模型组 3 2.51±0.30* 2.14±0.28* 3.28±0.26* 2.56±0.20* Nrf2过表达组 3 1.72±0.14*# 1.57±0.15*# 2.10±0.29*# 1.80±0.11*# HO-1过表达组 3 1.79±0.22*# 1.51±0.17*# 1.80±0.21*# 1.64±0.09*# HO-1沉默+Nrf2过表达组 3 2.30±0.20*▲△ 2.00±0.1*▲△ 2.99±0.23*▲△ 2.24±0.17*▲△ F — 19.82 20.55 43.75 37.68 P — < 0.01 < 0.01 < 0.01 < 0.01 MS组内 — 0.048 0.031 0.053 0.026 q检验: 与对照组比较*P < 0.05;与模型组比较#P < 0.05;与Nrf2过表达组比较▲P < 0.05;与HO-1过表达组比较△P < 0.05 表 4 各组心肌细胞内GRP78、ATF6、CHOP及Caspase-3 mRNA的相对表达水平比较(x±s)
Nrf2/HO-1通路通过调控内质网应激改善小鼠心肌细胞缺氧/复氧损伤的作用研究
Nrf2/HO-1 pathway improves anoxia/reoxygenation-induced injury in murine cardiomyocytes via regulating endoplasmic reticulum stress
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摘要:
目的探讨Nrf2/HO-1信号上调对小鼠心肌细胞缺氧/复氧损伤的改善作用及相关机制。 方法小鼠原代心肌细胞分为正常培养处理和缺氧/复氧处理,其中缺氧/复氧处理的心肌细胞分为模型组、Nrf2过表达组、HO-1过表达组、HO-1沉默+Nrf2过表达组。采用MTT法检测细胞活性,TUNEL染色检测细胞凋亡,ELISA法检测细胞培养上清中心肌肌钙蛋白Ⅰ(cTnⅠ)及肌酸激酶同工酶(CK-MB)含量,荧光定量PCR检测内质网应激相关分子水平。 结果小鼠心肌细胞缺氧/复氧处理后,心肌细胞活性降低、细胞凋亡增加及细胞培养上清中cTnⅠ和CK-MB含量升高(P < 0.05)。Nrf2或HO-1过表达可有效减轻缺氧/复氧诱导的心肌细胞损伤(P < 0.05)。给予HO-1基因沉默预处理后,Nrf2过表达产生的细胞保护作用明显减弱(P < 0.05)。此外,缺氧/复氧处理后,心肌细胞内GRP78、ATF6、CHOP和Caspase-3的mRNA表达量升高(P < 0.05)。Nrf2或HO-1过表达引起GRP78、ATF6、CHOP和Caspase-3表达水平下调(P < 0.05),而下调HO-1水平可使Nrf2过表达对内质网应激信号转导的抑制作用减弱(P < 0.05)。 结论Nrf2/HO-1通路表达上调可有效改善缺氧/复氧诱导的心肌细胞损伤,其机制可能在于抑制内质网应激以及下游的细胞凋亡通路信号转导。 -
关键词:
- 急性心肌梗死 /
- 缺氧/复氧损伤 /
- 内质网应激 /
- Nrf2/HO-1通路
Abstract:ObjectiveTo discuss the effect of Nrf2/HO-1 up-regulation on improving anoxia/reoxygenation-induced injury in murine cardiomyocytes and its related mechanism. MethodsThe primary murine cardiomyocytes were divided into normal culture treatment and anoxia/reoxygenation treatment, and the anoxia/reoxygenation treated cardiomyocytes were divided into model group, Nrf2 overexpression group, HO-1 overexpression group, HO-1 silence+Nrf2 overexpression group.Cell viability was detected by MTT assay, apoptosis was analyzed by TUNEL staining, cardiac troponin Ⅰ(cTnⅠ) and creatine kinase isoenzyme MB(CK-MB) contents in cell culture supernatant were determined by ELISA, and levels of endoplasmic reticulum stress-related molecules were measured by fluorescence quantitative PCR. ResultsAfter anoxia/reoxygenation treatment, the activity decreased, apoptosis increased, and the contents of cTnⅠ and CK-MB in cell culture supernatant of murine cardiomyocytes increased(P < 0.05).Overexpression of Nrf2 or HO-1 could effectively alleviate anoxia/reoxygenation-induced injury in murine cardiomyocytes(P < 0.05).After pretreatment with HO-1 gene silencing, the protection effect of Nrf2 overexpression was significantly weakened(P < 0.05).In addition, after anoxia/reoxygenation treatment, the mRNA expressions of GRP78, ATF6, CHOP and Caspase-3 in cardiomyocytes increased(P < 0.05).Overexpression of Nrf2 or HO-1 resulted in down-regulation of the expression levels of GRP78, ATF6, CHOP and Caspase-3(P < 0.05), while down-regulation of HO-1 level reduced the inhibitory effect of Nrf2 overexpression on endoplasmic reticulum stress signal transduction(P < 0.05). ConclusionsThe up-regulation of Nrf2/HO-1 pathway can effectively improve anoxia/reoxygenation-induced injury in cardiomyocytes, which may be related to the suppression of endoplasmic reticulum stress and its downstream apoptosis signaling transduction. -
表 1 各组目的基因表达情况(x±s)
分组 n Nrf2 mRNA HO-1 mRNA 对照组 3 0.95±0.04 1.04±0.05 过表达组 3 2.63±0.44 3.25±0.31* 沉默组 3 — 0.38±0.08* F — 6.59△ 193.67 P — < 0.01 < 0.01 MS组内 — — 0.035 △示t′值; q检验: 与对照组比较*P < 0.05 表 2 各组心肌细胞活性比较(x±s)
分组 n OD值 F P MS组内 对照组 5 1.01±0.09 27.75 < 0.01 0.007 模型组 5 0.51±0.09* Nrf2过表达组 5 0.71±0.06*# HO-1过表达组 5 0.72±0.08*# HO-1沉默+Nrf2过表达组 5 0.56±0.09*▲△ q检验: 与对照组比较*P < 0.05;与模型组比较#P < 0.05;与Nrf2过表达组比较▲P < 0.05;与HO-1过表达组比较△P < 0.05 表 3 各组细胞凋亡率及细胞培养上清中cTnⅠ和CK-MB含量比较(x±s)
分组 n 细胞凋亡率/% cTnⅠ /(pg/mL) CK-MB /(U/L) 对照组 4 10.13±3.11 42.98±13.52 20.89±11.06 模型组 4 59.78±9.16* 452.30± 47.44* 93.16±7.56* Nrf2过表达组 4 41.78±4.1*# 344.50±52.93*# 64.94±13.80*# HO-1过表达组 4 40.21±4.98*# 312.20±46.07*# 61.52±9.05*# HO-1沉默+Nrf2过表达组 4 58.15±8.01*▲△ 450.00± 43.69*▲△ 89.14±8.06*▲△ F — 40.03 45.05 24.16 P — < 0.01 < 0.01 < 0.01 MS组内 — 39.870 2 022.489 103.321 q检验: 与对照组比较*P < 0.05;与模型组比较#P < 0.05;与Nrf2过表达组比较▲P < 0.05;与HO-1过表达组比较△P < 0.05 表 4 各组心肌细胞内GRP78、ATF6、CHOP及Caspase-3 mRNA的相对表达水平比较(x±s)
分组 n GRP78 ATF6 CHOP Caspase-3 对照组 3 1.06±0.21 0.98±0.12 1.11±0.14 1.09±0.20 模型组 3 2.51±0.30* 2.14±0.28* 3.28±0.26* 2.56±0.20* Nrf2过表达组 3 1.72±0.14*# 1.57±0.15*# 2.10±0.29*# 1.80±0.11*# HO-1过表达组 3 1.79±0.22*# 1.51±0.17*# 1.80±0.21*# 1.64±0.09*# HO-1沉默+Nrf2过表达组 3 2.30±0.20*▲△ 2.00±0.1*▲△ 2.99±0.23*▲△ 2.24±0.17*▲△ F — 19.82 20.55 43.75 37.68 P — < 0.01 < 0.01 < 0.01 < 0.01 MS组内 — 0.048 0.031 0.053 0.026 q检验: 与对照组比较*P < 0.05;与模型组比较#P < 0.05;与Nrf2过表达组比较▲P < 0.05;与HO-1过表达组比较△P < 0.05 -
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