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  南方医科大学学报  2018, Vol. 38Issue (5): 612-619  DOI: 10.3969/j.issn.1673-4254.2018.05.18.
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徐文明, 林建聪, 陈美姬, 张常然, 李延兵. 糖原合酶激酶-3β与内质网应激相互作用参与高糖引起的人脐静脉内皮细胞损伤[J]. 南方医科大学学报, 2018, 38(5): 612-619. DOI: 10.3969/j.issn.1673-4254.2018.05.18.
XU Wenming, LIN Jiancong, CHEN Meiji, ZHANG Changran, LI Yanbing. Interaction between glycogen synthase kinase-3β and endoplasmic reticulum stress is involved in high glucose-induced injury in human umbilical vein endothelial cells[J]. Journal of Southern Medical University, 2018, 38(5): 612-619. DOI: 10.3969/j.issn.1673-4254.2018.05.18.

基金项目

广州市科技惠民专项基金(1346000270)

作者简介

徐文明,副主任医师,E-mail: xwm920018@163.com

通信作者

李延兵,教授,博士导师,E-mail: easd04lyb@126.com

文章历史

收稿日期:2018-03-07
糖原合酶激酶-3β与内质网应激相互作用参与高糖引起的人脐静脉内皮细胞损伤
徐文明 1, 林建聪 1, 陈美姬 2, 张常然 1, 李延兵 3     
1. 中山大学附属第一医院东院 普通内科,广东 广州 510700;
2. 中山大学附属第一医院东院 儿科,广东 广州 510700;
3. 中山大学附属第一医院内分泌科,广东 广州 510080
摘要: 目的 糖原合酶激酶-3β(GSK-3β)与内质网应激(ERS)相互作用是否参与高糖引起的人脐静脉内皮细胞(HUVECs)损伤。方法 应用40 mmol/L葡萄糖作用HUVECs 24 h构建高糖血管内皮细胞损伤模型。应用Western blot法检测GSK-3β、糖调节蛋白78(GRP78)、CHOP和cleaved caspase-3蛋白的表达水平;CCK-8法检测细胞存活率;Hoechst 33258核染色荧光显微镜照相法测定细胞凋亡;DCFH-DA染色荧光显微镜照相法测定胞内活性氧(ROS)水平;罗丹明123(Rh123)染色荧光显微镜照相法测定线粒体膜电位(MMP)。结果 应用40 mmol/L葡萄糖处理HUVECs 3~24 h,磷酸化(p)-GSK-3β表达减少,与Con组比较,差异具有统计学意义(P < 0.05);用高糖处理HUVECs 1~24 h,对促进GRP78和CHOP蛋白表达呈显著的时间依赖性,与Con组比较,差异具有统计学意义(P < 0.05);氯化锂(LiCl,GSK-3β抑制剂)能减轻高糖引起的ERS,使GRP78和CHOP蛋白表达减少,与高糖组比较,差异具有统计学意义(P < 0.01);4-苯基丁酸(4-PBA,ERS抑制剂)减弱高糖对GSK-3β的激活作用,使p-GSK-3β表达增多,与高糖组比较,差异具有统计学意义(P < 0.01)。高糖处理HUVECs 24 h能引起细胞存活率降低、凋亡细胞、cleaved caspase-3表达和ROS生成增多及MMP丢失等损伤;在高糖作用前,应用LiCl或4-PBA预处理60 min均减轻高糖引起的上述损伤,与高糖组分别比较,差异均具有统计学意义(P < 0.01)。结论 在高糖损伤的HUVECs,存在GSK-3β与ERS的相互作用并参与高糖对HUVECs的损伤。
关键词: 糖原合酶激酶-3β    内质网应激    相互作用    人脐静脉内皮细胞    高糖    
Interaction between glycogen synthase kinase-3β and endoplasmic reticulum stress is involved in high glucose-induced injury in human umbilical vein endothelial cells
XU Wenming1, LIN Jiancong1, CHEN Meiji2, ZHANG Changran1, LI Yanbing3     
1. Department of Internal Medicine, Huangpu Division of First Affiliated Hospital of Sun Yat-sen University, Guangzhou 510700, China;
2. Department of Pediatrics, Huangpu Division of First Affiliated Hospital of Sun Yat-sen University, Guangzhou 510700, China;
3. Department of Endocrinology, First Affiliated Hospital of Sun Yat-sen University, Guangzhou 510080, China
Abstract: Objective To explore the role of the interaction between glycogen synthase kinase- 3β (GSK- 3β) and endoplasmic reticulum stress (ERS) in the high glucose (HG)-induced injury in human umbilical vein endothelial cells (HUVECs). Methods HUVECs treated with 40 mmol/L glucose for 24 h were examined for expression levels of GSK-3β, GRP78, CHOP and cleaved caspase-3 protein using Western blotting. The cell viability was examined using CCK-8 assay and cell apoptosis was detected with Hoechst 33258 nuclear staining and photofluorography. The intracellular level of reactive oxygen species (ROS) was measured with dichlorfluoresein staining and photofluorography. Mitochondrial membrane potential (MMP) was tested by rhodamine 123 (Rh123) staining and photofluorography. Results Treatment of HUVECs with 40 μmol/L glucose for 3-24 h activated GSK-3β in a time-dependent manner, leading to significantly down-regulated expression of phosphorylated (p)-GSK- 3β (P < 0.05). HG exposure of the cells for 1-24 h induced ERS, evidenced by time-dependently up-regulated expression of GRP78 and CHOP (P < 0.05). LiCl, an inhibitor of GSK-3β, attenuated HG-induced ERS and significantly lowered the expression levels of GRP78 and CHOP (P < 0.01). 4-PBA, an inhibitor of ERS, obviously ameliorated the activation of GSK-3β by HG as shown by the increase in p-GSK-3β expression level (P < 0.01). HG exposure for 24 h induced obvious injuries in HUVECs, which exhibited decreased cell viability, increased cell apoptosis, increased expression of cleaved caspase-3 and ROS generation, and loss of MMP. Pretreatment of the cells with LiCl or 4-PBA for 60 min before HG exposure significantly lessened the cell injuries (P < 0.01). Conclusion Interactions between GSK-3β and ERS occur in HUVECs exposed to HG and participate in HG-induced cell injuries.
Key words: glycogen synthase kinase-3β    endoplasmic reticulum stress    interaction    human umbilical vein endothelial cells    high glucose    

糖尿病是一种以高血糖为特征的代谢性疾病,而大血管并发症是其致死、致残最主要的原因[1]。高血糖引起血管内皮细胞(VECs)功能失调是血管病的始动因子[2-4]。探讨高血糖引起VEC损伤的病理生理机制对防治糖尿病血管病的发生极其重要。糖原合酶激酶-3(GSK-3)[5]及内质网应激(ERS)在糖尿病心血管并发症中的作用日益受到重视[6]

GSK-3是一种丝氨酸/苏氨酸激酶,被认为是多种细胞事件和信号通路的调节者,包括GSK-3α和GSK-3β两个成员。与大部分的蛋白激酶不同,GSK-3在磷酸化状态时是不活动的。GSK- 3α结构中的Ser21或GSK-3β中的Ser9去磷酸化导致它们被激活并对各种刺激产生反应[7-8]。糖尿病肾病大鼠肾组织的GSK-3β活性增强,GSK-3β抑制剂可抑制GSK-3β活性,减轻肾组织的病理改变及尿蛋白量[9]。高糖引起H9C2细胞凋亡及GSK-3β活性增强,小干扰RNA沉默GSK-3β后能保护心肌细胞对抗高糖引起的损伤[5]。在糖尿病大鼠,GSK- 3β抑制剂通过调控Nrf2/TrxR2信号通路保护肾脏对抗缺血再灌注引起的损伤[10]。有关GSK-3β在高糖损伤血管内皮细胞的作用及其机制尚未见相关研究。

内质网应激(ERS)是指某些因素使ER生理功能发生紊乱的一种亚细胞器病理状态。高浓度的葡萄糖能激活内皮细胞,但长期高血糖则导致持续的ERS[11]。适当程度的ERS对维持细胞的稳定是有利的,而长期的ERS则能引起细胞凋亡及发生许多疾病[12]。ERS在T2DM的VECs损伤中起着重要的作用[13-15]。高糖能引起人脐静脉内皮细胞(HUVECs)凋亡、ERS及内皮素-1生成增多;Mir-149-5P能通过抑制ERS(降低GRP78、CHOP表达)及增加抗凋亡蛋白(Bcl-2)表达等机制保护HUVECs对抗高糖引起的损伤[6]。在胰岛瘤细胞模型,ERS引起的凋亡与增加GSK-3β活性有关[16]。在脂多糖(LPS)诱发的肝损伤中,GSK-3β与促进ERS引起的凋亡有关[17]。因此,我们推测在高糖引起的VECs损伤中,可能存在GSK-3β与ERS相互作用,而且这种相互作用可能是高糖损伤VECs的一个重要的病理生理机制。

本研究拟建立高糖处理的HUVECs损伤模型,探讨GSK-3β与ERS是否存在相互作用;GSK-3β和ERS在高糖损伤血管内皮细胞中的多种作用,为深入阐明高糖对血管内皮细胞的损伤机制提供实验依据。

1 材料和方法 1.1 材料和试剂

抗GSK- 3β、抗磷酸化(p)-GSK-3β(Ser9)、抗GRP78、抗CHOP和抗cleaved caspase-3抗体购自Cell Signaling;双氯荧光素(DCFH-DA)、罗丹明123(Rh 123)、Hoechst 33258染料、氯化锂(LiCl,GSK-3β的抑制剂)、4-苯基丁酸(4-PBA,ERS的抑制剂)购自SigmaAldrich;特级胎牛血清(FBS)购自Gibco BRL;细胞计数试剂盒8(CCK-8)由Dojindo Lab(Japan)提供;DMEM培养基由Hyclone供应。HUVECs由中山大学实验动物中心细胞库供应。

1.2 细胞培养及实验分组

在含5% CO2的37 ℃恒温培养箱中、采用含10% FBS的DMEM培养HUVECs,当细胞生长至约80%的融合状态时可进行实验。实验分为6组:(1)Con组:DMEM培养基作用HUVECs 24 h;(2)高糖(HG)组:40 mmol/L葡萄糖作用HUVECs 24 h;(3)LiCl+ HG组:10 mmol/L LiCl预处理HUVECs 60 min,再予40 mmol/L葡萄糖作用24 h;(4)4-PBA+HG组:20 μmol/L 4-PBA预处理HUVECs 60 min,再予40 mmol/L葡萄糖作用24 h;(5)LiCl组:10 mmol/L LiCl预处理HUVECs 60 min,再予DMEM作用24 h;(6)4-PBA组:20 μmol/L 4-PBA预处理HUVECs 60 min,再予DMEM作用24 h。

1.3 GSK-3β、GRP78、CHOP和cleaved caspase-3蛋白水平测定

HUVECs在60 mm培养皿中生长至约80%融合度时,给予不同的处理后加入细胞裂解液作用30 min后,高速离心10 min后取上清液进行蛋白定量(BCA法)。等量蛋白经十二烷基硫酸钠聚丙烯酰胺凝胶(SDSPAGE)电泳分离后,转移至PVDF膜上,5%脱脂奶粉常温孵育1 h后加入Ⅰ抗稀释液[包括抗GSK-3β、抗pGSK-3β(Ser9)、抗cleaved caspase-3、抗GRP78、抗CHOP和GAPDH,浓度均为1:1000],4 ℃作用过夜后加入Ⅱ抗稀释液(浓度为1:3000)孵育1.5 h。ECL法使PVDF膜显色,暗室中曝光到X线片上,凝胶成像扫描系统分析结果。实验重复5次。

1.4 细胞存活率测定

在96孔板中培养HUVECs,当细胞生长至约80%的融合度时,按各分组处理后,吸去细胞培养液,PBS液冲洗3次,加入CCK-8溶液10 μL/孔,37 ℃恒温培养箱内孵育2.5 h,酶标仪上读取A 450 nm;细胞存活率按照以下公式计算:细胞存活率(%)=处理组A /对照组A× 100%。实验重复5次。

1.5 细胞凋亡检测

HUVECs在24孔板中生长至约80%的融合度时,按照分组给予不同处理后,4%的多聚甲醛固定10 min,加入用Hoechst 33258染料稀释液,37 ℃温箱中作用30 min,荧光显微镜下可观察到:正常的细胞呈弥散均匀的低密度荧光,凋亡细胞则表现为细胞核呈现浓缩致密的固缩形态或颗粒荧光,随机照片记录5个高倍镜视野(放大200倍,以下同)。应用Image J 1.47i软件计算平均荧光强度(MFI),对每组数据进行统计分析。实验重复5次。

1.6 细胞内ROS水平测定

HUVECs在24孔板中生长至融合度约80%时,经不同处理后,加入DCFH-DA染液后于37 ℃温箱中作用30 min,荧光显微镜(TE-2000 Nikon)下随机照片记录5个高倍镜视野,应用Image J 1.47i计算出绿色荧光的MFI(数值大小能间接反映ROS水平的高低),并对每组数据进行统计分析。实验重复5次。

1.7 线粒体膜电位(MMP)水平测定

HUVECs在24孔板中生长至约80%的融合度时,按照分组给予不同处理后,加入Rh 123染液,37 ℃温箱中作用30 min,荧光显微镜下随机照片记录5个高倍镜视野,应用图像分析软件计算绿色荧光的MFI(数值大小可反映MMP的高低),并对每组数据进行统计分析。实验重复5次。

1.8 统计学处理

利用SPSS 19.0软件进行数据分析,结果以均数±标准差表示,单因素方差分析用于多个样本均数间的比较,结果有统计学意义再采用SNK-q检验进行均数间的两两比较,P < 0.05为差异有统计学意义。

2 结果 2.1 高糖激活人脐静脉内皮细胞GSK-3β

40 mmol/L葡萄糖(HG)作用人脐静脉内皮细胞(HUVECs)1~24 h对磷酸化(p)-GSK-3β的影响(图 1AB)。当HG作用HUVECs 3 h可使p-GSK-3β的表达水平明显下降(反映GSK-3β被激活),与Con组比较,差异具有统计学意义(P < 0.05);随着作用时间的延长(6、9、12、24 h),呈显著的时间-剂量依赖关系,与Con组比较,差异具有统计学意义(P < 0.01)。在上述作用时间段,HG对HUVECs的GSK-3β表达水平无明显的影响。

图 1 高糖对HUVECs的GSK-3β的激活作用 Figure 1 Effect of high glucose (HG, 40 mmol/L) exposure for 24 h on activation of glycogen synthase kinase- 3β (GSK- 3β) in human umbilical vein endothelial cells (HUVECs). A: Expression levels of p-GSK-3β and GSK- 3βsemi- quantified by Western blot analysis; B, C: Densitometric analysis of p- GSK- 3β and GSK- 3β expression levels. *P < 0.05, **P < 0.01 vs control group (n=5)
2.2 高糖诱发人脐静脉内皮细胞ERS

HG作用HUVECs 1 h可明显地增加GRP78的表达水平,与Con组比较,差异具有统计学意义(P < 0.05,图 2AB)。随着作用时间的延长(3、6、9、12、24 h),HG对GRP78表达水平的促进作用呈显著的时间-剂量依赖关系,与Con组比较,差异具有统计学意义(P < 0.01);HG作用HUVECs 3 h开始引起CHOP蛋白表达显著增多,随着作用时间的延长,这种作用呈显著的时间-剂量依赖关系(P < 0.01,图 2AC)。

图 2 高糖引起HUVECs的ERS Figure 2 HG (40 mmol/L) exposure for 24 h induces endoplasmic reticulum stress (ERS) in HUVECs. A: Expression levels of GRP78 and CHOP semi-quantified by Western blot analysis; B, C: Densitometric analysis of GRP78 and CHOP expression levels. *P < 0.05, **P < 0.01 vs control group (n=5)
2.3 活化的GSK-3β参与高糖引起的人脐静脉内皮细胞的ERS

当HG作用HUVECs 24 h可明显地诱发ERS,GRP78和CHOP的表达水平明显升高(P < 0.01)。在HG产生作用前,应用10 mmol/L LiCl(GSK-3β抑制剂)预处理HUVECs 60 min,HG对GRP78和CHOP表达的促进作用明显减弱,与HG组比较,差异具有统计学意义(P < 0.01,图 3)。单独应用10 mmol/LLiCl处理HUVECs 60 min,HG对GRP78和CHOP表达水平影响不明显。

图 3 活化的GSK-3β介导HG引起的HUVECs ERS Figure 3 Activated GSK-3β mediates HG-induced ERS in HUVECs. HUVECs were pre-treated with 10 mmol/L LiCl for 60 min before exposure to 40 mmol/L glucose (HG) for 24 h. A: Expression levels of GRP78 and CHOP semi-quantified by Western blot analysis; B, C: Densitometric analysis of GRP78 and CHOP expression levels. **P < 0.01 vs control group; ##P < 0.01 vs HG-treated cels (n=5). HG: High glucose
2.4 ERS参与高糖对人脐静脉内皮细胞GSK-3β的激活作用

HG作用HUVECs 24 h可激活GSK-3β,p-GSK-3β表达水平明显降低,与Con组比较,差异具有统计学意义(P < 0.01,图 4AB)。在HG产生作用前,应用20 μmol/L 4-PBA(ERS抑制剂)预处理HUVECs 60 min,p-GSK- 3β表达水平升高,与单独HG组比较,差异具有统计学意义(P < 0.01)。单独20 μmol/L 4-PBA处理HUVECs 60 min,p-GSK-3β表达水平的影响不显著。

图 4 ERS参与高糖对HUVECs GSK-3β的激活作用 Figure 4 ERS is involved in HG-induced GSK-3β activation in HUVECs. HUVECs were pre-treated with 20 μmol/L 4-PBA for 60 min before exposure to 40 mmol/L glucose (HG) for 24 h. A: Expression levels of p- GSK- 3β and GSK-3βsemi-quantified by Western blot analysis. B, C: Densitometric analysis of p-GSK-3β and GSK-3β expression levels. **P < 0.01 vs control group; ##P < 0.01 vs HG-treated group (n=5). HG: High glucose
2.5 GSK-3β和ERS介导高糖引起的人脐静脉内皮细胞存活率降低

HG处理HUVECs 24 h可引起明显的细胞毒性作用,细胞存活率明显降低,与Con组比较,差异具有统计学意义(P < 0.01,图 5)。在HG处理前,应用10 mmol/L LiCl或20 μmol/L 4-PBA预处理HUVECs 60 min,可分别对抗HG引起的细胞毒性,使细胞存活率升高,与单独HG组比较,差异具有统计学意义(P < 0.01)。单独用10 mmol/L LiCl或20 μmol/L 4-PBA处理HUVECs 60 min,对细胞存活率影响不明显。

图 5 GSK-3β和ERS参与高糖引起的HUVECs存活率降低 Figure 5 GSK-3β and ERS are implicated in HG-induced decrease in HUVEC viability. HUVECs were treated with 40 mmol/L glucose for 24 h with or without pre- treatment with 10 mmol/L LiCl or 20 μmol/L 4-PBA for 60 min. Cell viability was detected using the Cell counting Kit-8 (CCK-8) assay. **P < 0.01 vs control group; ##P < 0.01 vs HG-treated group (n=5). HG: High glucose
2.6 GSK-3β和ERS介导高糖引起的人脐静脉内皮细胞凋亡

HG作用HUVECs 24 h可引起凋亡细胞数量显著增加,与Con组比较,差异具有统计学意义(P < 0.01,图 6AB)。在HG作用前,应用10 mmol/L LiCl或20 μmol/L 4-PBA预处理HUVECs 60 min,均能明显地减小凋亡细胞数量,与单独HG组比较,差异均具有统计学意义(P < 0.01)。用10 mmol/L LiCl或20 μmol/L 4-PBA处理HUVECs 60 min,对凋亡细胞数量无明显的影响。HG处理HUVECs 24 h引起cleaved caspase-3[为凋亡效应器)表达水平明显升高,与Con组比较,差异具有统计学意义(P < 0.01,图 6C~F)]。在HG处理前,应用10 mmol/L LiCl或20 μmmol/L 4-PBA预处理60 min,均能明显地减少cleaved caspase-3的表达水平,与HG处理组比较,差异均具有统计学意义(P < 0.01)。用10 m mmol/L LiCl或20 μmmol/L 4-PBA处理HUVECs 60 min,对cleaved caspase-3的表达水平无明显的影响。

图 6 GSK-3β和ERS参与高糖引起的HUVECs凋亡 Figure 6 GSK-3β and ERS participate in HG-induced apoptosis in HUVECs. HUVECs were treated with 40 mmol/L glucose for 24 h with or without pre-treatment with 10 mmol/L LiCl or 20 μmol/L 4-PBA for 60 min. A: Detection of cell apoptosis using Hoechst 33258 nuclear staining followed by fluorescence imaging; B: Percentage of apoptotic cells in different groups analyzed using Image J 1.47i software; C, E: Expression levels of cleaved caspase-3 semi-quantified by Western blot analysis; D, F: Densitometric analysis of cleaved caspase-3 expression levels. **P < 0.01 vs the control group; ##P < 0.01 vs HG-treated group (n=5). HG: High glucose
2.7 GSK-3β和ERS介导高糖引起的HUVECs的氧化应激

应用DCFH-DA染色法检测细胞内活性氧(ROS)水平。HG处理HUVECs 24 h,胞内DCFH-DA的MFI明显升高,与Con组比较,差异具有统计学意义(P < 0.01,图 7AB)。在HG处理前,应用10 mmol/L LiCl或20 μmol/L 4-PBA预处理HUVECs 60 min,均能降低胞内DCFH-DA的MFI,与HG组分别比较,差异均具有统计学意义(P < 0.01)。10 mmol/L LiCl或20 μmol/L 4- PBA处理HUVECs 60 min,对胞内ROS水平表达无明显影响。

图 7 GSK-3β和ERS参与高糖引起的HUVECs的氧化应激 Figure 7 GSK-3β and ERS are involved in HG- induced oxidative stress in HUVECs. HUVECs were treated with 40 mmol/Lglucose for 24 h with or without pre-treatment with 10 mmol/L LiCl or 20 μmol/L 4-PBA for 60 min. A: Intracellular ROS generation measured by 2'7-dichlorodihydrofluoresein diacetate (DCFHDA) staining followed by photofluorography; B: Quantitative analysis of the mean fluorescence intensity (MFI) using Image J 1.47i software. **P < 0.01 vs control group; ##P < 0.01 vs HG-treated group (n=5). HG: High glucose
2.8 GSK-3β和ERS介导高糖引起的人脐静脉内皮细胞线粒体膜电位丢失

HG处理HUVECs 24 h引起线粒体损伤,线粒体膜电位(MMP)丢失,即Rh123荧光染料的MFI降低,与Con组相比,差异具有统计学意义(P < 0.01,图 8AB)。在HG产生作用前,应用10 mmol/L LiCl或20 μmol/L4-PBA预处理HUVECs 60 min,均能拮抗HG引起的MMP丢失,与HG处理组分别比较,差异具有统计学意义(P < 0.01)。单独应用10 mmol/LLiCl或20 μmol/L4-PBA处理HUVECs 60 min,对MMP水平表达无明显影响。

图 8 GSK-3β和ERS参与高糖引起的人脐静脉内皮细胞MMP丢失 Figure 8 GSK-3β and ERS contribute to HG-induced dissipation of mitochondrial membrane potential in HUVECs. HUVECs were treated with 40 mmol/L glucose for 24 h with or without pre-treatment with 10 mmol/L LiCl or 20 μmol/L 4-PBA for 60 min. A: MMP detected using the fluorescent dye Rh123; B: Quantitative analysis of the mean fluorescence intensity (MFI) using Image J 1.47i software. **P < 0.01 vs control group; ##P < 0.01 vs HG-treated group (n=5). HG: High glucose
3 讨论

高血糖是引起糖尿病心血管并发症的最重要因素[17-19]。高血糖可通过引起细胞凋亡、细胞毒性、炎症、氧化应激、损伤线粒体等作用引起血管内皮细胞功能障碍[20-22]。内皮素-1[6]、氧化应激[21]、瘦素/瘦素受体通路[21]、JAK/STAT通路[22]及沉默信息调节子1[23]等参与高糖对血管内皮细胞的损伤。GSK-3(特别是GSK-3β)[5]及ERS[6]在糖尿病心血管并发症中的作用受到学者们的关注。

GSK-3β是导致胰岛素缺失和胰岛素抵抗的一个重要因素[24]。高糖引起H9C2心肌细胞GSK-3β活性增强,抑制GSK-3β能减轻高糖引起心肌细胞凋亡[5]。在高糖处理的HUVECs模型,GSK-3β活性增强、细胞凋亡增多、线粒体膜通透性丢失及细胞色素C释放增多[25]。该研究没有应用GSK-3β抑制剂或小干扰RNA沉默GSK-3β等方法进一步证实GSK-3β在高糖损伤HUVECs中的作用[25]。本研究观察到高糖能引起HUVECs多种损伤,表现为细胞存活率降低、凋亡细胞数量增多、ROS生成增多及MMP丢失;另外,高糖能增加HUVECs GSK-3β活性,这与Liu等人的报道相一致[25]。本研究应用GSK-3β抑制剂后,高糖引起的上述内皮细胞损伤明显减轻,提示GSK-3β参与高糖引起的细胞毒性、细胞凋亡、氧化应激及线粒体损伤,进一步证实了GSK-3β在高糖损伤血管内皮细胞中的作用[25]

抑制ERS能减轻2型糖尿病心肌梗塞[26]。高糖能引起HUVECs发生ERS和细胞凋亡[27]。本研究证实糖能在HUVECs诱发ERS,表现为GRP78和CHOP蛋白表达增多,这与高糖作为应激刺激激发ERS有关。4- PBA能保护血管内皮细胞对抗高糖引起的损伤,表现为细胞存活率升高,凋亡细胞数量、ROS生成及MMP丢失减少,提示ERS参与高糖引起的血管内皮细胞多种损伤[28-30],这为把ERS作为一个靶点来防治高糖引起的血管并发症提供了实验依据。

综上所述,在高糖处理的HUVECs,应用LiCl能抑制高糖引起的ERS,4-PBA能抑制高糖对GSK-3β的激活作用。这证明GSK-3β与ERS在高糖损伤HUVECs过程中,存在着相互作用,即激活的GSK-3β能加强ERS,ERS也能促进GSK-3β激活,这可能是高糖损伤血管内皮细胞的作用机制,为防治糖尿病血管并发症提供了一个新思路。

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