摘要目的 观察短链酰基辅酶A脱氢酶(SCAD)在人脐静脉内皮细胞(HUVEC)凋亡中的变化,探讨其与细胞凋亡的关系.方法 取正常培养2～3 d的HUVEC,采用叔丁基过氧化氢(tBHP)刺激HUVEC建立细胞凋亡模型,分别用0、10、20、30、40、50 μmol/L的tBHP干预HUVEC 12 h,用50 μmol/L的tBHP干预HUVEC 0、3、6、9、12 h,通过四甲基偶氮唑盐(MTT)比色法检测细胞活性、实时荧光定量聚合酶链反应(PCR)和蛋白质免疫印迹试验(Western Blot)分别检测SCAD的mRNA及蛋白表达,以筛选tBHP干预HUVEC的最佳浓度和时间.用小干扰RNA(siRNA)干扰HUVEC的SCAD基因(siRNA274、siRNA414、siRNA679),通过检测SCAD mRNA和蛋白表达及SCAD酶活性,以筛选siRNA最佳干扰序列.然后以最佳干扰序列及tBHP同时干预HUVEC,通过检测细胞活性、细胞凋亡率、SCAD酶活性、SCAD mRNA和蛋白表达、活性氧(ROS)含量、三磷酸腺苷(ATP)含量和游离脂肪酸(FFA)含量,观察SCAD对HUVEC细胞凋亡的影响.结果 ① 随tBHP浓度增加及干预时间延长,细胞活性及SCAD mRNA和蛋白表达均逐渐降低,呈浓度和时间依赖性,以50 μmol/L tBHP干预HUVEC 12 h各指标下降最为显著.② 在siRNA274、siRNA414、siRNA679 3条干扰序列中,siRNA679转染在降低SCAD mRNA和蛋白表达及酶活性方面最为显著.③ 与空白对照组相比,siRNA679干扰后细胞活性明显下降(A值:0.48±0.09 比1.00±0.09,P＜0.01),细胞凋亡率明显增加〔(29.96±2.09)% 比(2.90±1.90)%, P＜0.01〕,HUVEC中SCAD mRNA和蛋白表达、SCAD酶活性及ATP含量均显著下降〔SCAD mRNA(2-ΔΔCt):0.50±0.16 比 1.34±0.12, SCAD/α-Tubulin :0.67±0.11 比 1.00±0.06,SCAD 酶 活 性(kU/g):0.38±0.04 比0.53±0.04,ATP含量(μmol/g):0.14±0.02比0.19±0.01,均P＜0.05〕,FFA及ROS含量显著增加〔FFA(nmol/g):0.84±0.07比0.47±0.04, ROS(平均荧光强度):647.5±23.7比434.2±46.5,均P＜0.01〕.siRNA转染组各指标与tBHP诱导的HUVEC凋亡趋势一致.结论 SCAD表达失调可能参与HUVEC细胞凋亡过程,上调SCAD可能成为干预细胞凋亡的重要环节之一.

abstractsObjective To observe the changes of short-chain acyl-CoA dehydrogenase (SCAD) expression on human umbilical vein endothelial cell (HUVEC) apoptosis and investigate its relationship with apoptosis. Methods The HUVEC was cultured normally for 2-3 days. The apoptotic model of HUVEC was established by tert-butyl hydrogen peroxide (tBHP). The HUVEC was treated by different concentrations of tBHP (0, 10, 20, 30, 40, 50 μmol/L) for 12 hours and different time (0, 3, 6, 9, 12 hours) with 50 μmol/L tBHP to establish the apoptotic model of HUVEC. The cell viability was detected by methyl thiazolyl tetrazolium (MTT), the mRNA expression of SCAD was determined by real-time polymerase chain reaction (PCR), the protein expression of SCAD was achieved by Western Blot. The best concentrate and time were determined to interfere the HUVEC to achieve the apoptotic model of HUVEC. The SCAD gene of HUVEC was knocked down by RNA interference sequence (siRNA274, siRNA414, siRNA679). The mRNA expression of SCAD, the protein expression of SCAD and the activity of SCAD enzyme were detected to achieve the best RNA interference sequence. The HUVEC was intervened by the best RNA interference sequence and tBHP. The cell activity and apoptosis rate, the enzyme activity of SCAD, the mRNA and protein expression of SCAD, the contents of reactive oxygen species (ROS), aderosine triphosphate (ATP) and free fatty acid (FFA) were detected to observe the effect of SCAD on apoptosis of HUVEC. Results ① The cell viability, the mRNA expression and the protein expression of SCAD were decreased gradually in a concentration and time dependent manner with the increase of tBHP concentration and the prolongation of intervention time. The decline was most significant in the group of the 50 μmol/L tBHP to interfere HUVEC for 12 hours. ② The siRNA679 transfection was the most significant in reducing SCAD mRNA and protein expressions among the three interference sequences (siRNA274, siRNA414, siRNA679). ③ Compare with blank control group, the cell viability was significantly decreased in the siRNA679 group (A value: 0.48±0.09 vs. 1.00±0.09, P < 0.01), the apoptotic rate of HUVEC was significantly increased [(29.96±2.09)% vs. (2.90±1.90)%, P < 0.01], the expression of SCAD mRNA and SCAD protein, the activity of SCAD enzyme and the content of ATP were significantly decreased [SCAD mRNA (2-ΔΔCt): 0.50±0.16 vs. 1.34±0.12, SCAD/α-Tubulin: 0.67±0.11 vs. 1.00±0.06, the activity of SCAD enzyme (kU/g): 0.38±0.04 vs. 0.53±0.04, the content of ATP (μmol/g): 0.14±0.02 vs. 0.19±0.01, all P < 0.05], the contents of FFA and ROS were significantly increased [FFA (nmol/g): 0.84±0.07 vs. 0.47±0.04, ROS (average fluorescence intensity): 647.5±23.7 vs. 434.2±46.5, both P < 0.01]. Meanwhile, SCAD siRNA treatment triggered the same apoptosis as HUVEC treated with tBHP. Conclusions Down-regulation of SCAD may play an important role in HUVEC apoptosis. Increase in the expression of SCAD may become an important part in intervening HUVEC apoptosis.