半胱天冬氨酸蛋白酶-12小干扰RNA对小鼠肝细胞凋亡的阻抑

目的观察小鼠半胱天冬氨酸蛋白酶-12（caspase-12）基因特异性小干扰RNA（siRNA）构建的表达载体pRNAT-casp12对caspase-12基因的抑制及其对内质网应激介导的小鼠肝细胞凋亡的影响。方法以小鼠肝细胞株Hepa1-6为靶细胞，利用脂质体与重组质粒pRNAT-casp-2共转染，分别在转染24、48和72h后收集细胞，采用实时荧光定量PCR分析和Western印迹检测caspase-12的表达；利用毒胡萝b素（TG）诱导细胞，建立内质网应激介导的细胞凋亡模型，通过DNA梯带凝胶电泳检测，选出适合的诱导时间；TG诱导已转染了pRNAT—casp12的干扰组细胞后，以空质粒转染组为对照，利用Western印迹检测caspase-12蛋白表达水平的变化，通过DNA梯带凝胶电泳、流式细胞仪、Hoechst33258染色等方法检测细胞凋亡，观察caspase-12siRNA对细胞凋亡的影响。结果pRNAT—casp12转染细胞24、48和72h后，caspase-12mRNA的水平分别下降了45．6％、72．5％和59．5％；caspase-12蛋白表达下降了17．1％、37．3％和60．1％；2μmol／L TG处理细胞30h后，成功诱导细胞凋亡；与对照组相比，干扰组细胞经TG诱导后，caspase-12蛋白表达水平下降了54．6％，流式细胞仪检测发现早期调亡率下调了51．4％（P〈0．01）。结论小鼠caspase-12siRNA对Hepa1—6细胞caspase-12基因的表达具有显著的抑制作用，能够明显阻抑内质网应激介导的凋亡，有望发展成为新一代抗凋亡药物。     

The inhibition of human T cell proliferation by the caspase inhibitor z-VAD-FMK is mediated through oxidative stress

The caspase inhibitor benzyloxycarbony (Cbz)-l-Val-Ala-Asp (OMe)-fluoromethylketone (z-VAD-FMK) has recently been shown to inhibit T cell proliferation without blocking caspase-8 and caspase-3 activation in primary T cells. We showed in this study that z-VAD-FMK treatment leads to a decrease in intracellular glutathione (GSH) with a concomitant increase in reactive oxygen species (ROS) levels in activated T cells. The inhibition of anti-CD3-mediated T cell proliferation induced by z-VAD-FMK was abolished by the presence of low molecular weight thiols such as GSH, N-acetylcysteine (NAC) and l-cysteine, whereas d-cysteine which cannot be metabolised to GSH has no effect. These results suggest that the depletion of intracellular GSH is the underlying cause of z-VAD-FMK-mediated inhibition of T cell activation and proliferation. The presence of exogenous GSH also attenuated the inhibition of anti-CD3-induced CD25 and CD69 expression mediated by z-VAD-FMK. However, none of the low molecular weight thiols were able to restore the caspase-inhibitory properties of z-VAD-FMK in activated T cells where caspase-8 and caspase-3 remain activated and processed into their respective subunits in the presence of the caspase inhibitor. This suggests that the inhibition of T cell proliferation can be uncoupled from the caspase-inhibitory properties of z-VAD-FMK. Taken together, the immunosuppressive effects in primary T cells mediated by z-VAD-FMK are due to oxidative stress via the depletion of GSH.     

Zinc inhibits ethanol-induced HepG2 cell apoptosis

Alcohol consumption produces a variety of metabolic alterations in liver cells, associated with ethanol oxidation and with nonoxidative metabolism of ethanol, among others apoptosis of hepatocytes. As zinc is known as a potent antioxidant and an inhibitor of cell apoptosis, the aim of this paper was to investigate whether zinc supplementation could inhibit ethanol-induced HepG2 apoptosis, and whether this inhibition was connected with attenuation of oxidative stress and modulation of FasR/FasL system expression. The results indicated that zinc supplementation significantly inhibited ethanol-induced HepG2 cell apoptosis (measured by cytochrome c release from mitochondria and caspase-3 activation) by attenuation of reactive oxygen species (ROS) production, increase in the cellular level of GSH, inhibition of ethanol-induced sFasR and FasL overexpression and caspase-8 activation. These results indicate that zinc can inhibit ethanol-induced hepatocyte apoptosis by several independent mechanisms, among others by an indirect antioxidative effect and probably by inhibition of caspase-8 and caspase-9 activation.     

Inhibition of mitochondrial permeability transition prevents mitochondrial dysfunction,cytochrome c release and apoptosis induced by heart ischemia

Ischemia/reperfusion of heart causes contractile dysfunction, necrosis and/or apoptosis and is a major cause of human death, but the molecular mechanisms are unclear. We show that ischemia alone (without reperfusion) is sufficient to induce apoptosis and mitochondrial dysfunction, and we have investigated the mechanism responsible; 30 and 60 min stop-flow ischemia in Langendorff-perfused rat hearts induced progressive (a). release of cytochrome c from mitochondria to cytosol, (b). inhibition of the mitochondrial respiratory functions, (c). activation of caspase-3-like protease activity and (d). DNA strand breaks (however, only 2% of myocyte nuclei were TUNEL positive at 60 min). Fifteen minutes pre-perfusion of hearts with cyclosporin A, an inhibitor of mitochondrial-permeability transition (MPT), largely prevented all these ischemic changes. Pre-perfusion of hearts with FK506, an inhibitor of calcineurin, caused no protection. Pre-perfusion with DEVD-CHO, an inhibitor of caspase-3-like proteases, completely prevented ischemia-induced DNA strand breaks, but only partially blocked cytochrome c release and mitochondrial respiratory inhibition. Reperfusion of hearts after 30 min ischemia further stimulated caspase activity and nuclear apoptosis. We conclude that ischemia-induced MPT causes release of cytochrome c, which then activates the caspases that execute apoptosis and feedback to cause further cytochrome c release. The MPT-induced cytochrome c release is also largely responsible for the ischemic respiratory inhibition, which might contribute to contractile dysfunction or necrosis at reperfusion.     

告达庭增强TRAIL诱导的HepG2细胞凋亡

目的:研究C21甾体苷元告达庭对肿瘤坏死因子凋亡诱导配体(TRAIL)诱导的Hep G2肝癌细胞增殖和凋亡的影响,并进一步明确其作用机制。方法:采用MTT法和细胞集落形成实验检测告达庭与TRAIL联合对细胞增殖的影响;TUNEL染色法检测细胞凋亡的变化;免疫印迹实验分析蛋白的表达水平。结果:告达庭与TRAIL联合作用Hep G2细胞24 h后,细胞活力明显下降,细胞增殖受到抑制;同时,两者联用后细胞凋亡数目明显增加,显著高于告达庭和TRAIL单用诱导的细胞凋亡率;与对照相比,告达庭与TRAIL联用促进了caspase-3、caspase-7、caspase-9和PARP的活性切割,而凋亡抑制蛋白survivin的表达则下调。结论:告达庭能够增强TRAIL诱导Hep G2细胞凋亡,其机制可能与激活caspase家族因子的活性切割和抑制survivin的表达相关。     

复方甘草酸苷对小鼠暴发性肝功能衰竭保护作用及机制研究

目的　探讨复方甘草酸苷(SNMC)对小鼠暴发性肝功能衰竭(FLF)的保护作用及可能机制。方法　用D- 氨基半乳糖和脂多糖腹腔注射构建肝功能衰竭的小鼠模型,同时用SNMC对治疗组小鼠进行保护,观察各组小鼠存活率、肝功能、各种炎症因子及肝脏病理变化;电镜下观察线粒体结构的改变;应用末端转移酶标记技术(TUNEL)检测肝细胞原位凋亡的情况;应用免疫组化法分别检测肝组织中细胞色素C和天冬氨酸半胱氨酸蛋白酶3(caspase 3)的表达。结果　D 氨基半乳糖和脂多糖可以构建FLF模型,SNMC不同剂量组及不同给药时间组在降低酶学指标及血浆肿瘤坏死因子(TNF)- α、NO、内皮素(ET) -1、白细胞介素(IL) 6 水平,改善肝组织的损伤程度方面与模型组比较(多组间方差分析)差异均有统计学意义(P<0.01)。不同剂量和不同给药时间之间差异无统计学意义(P>0.05)。模型组和保护组之间的存活率差异有统计学意义(P<0.01)。同时给药小剂量组随着SNMC治疗时间的延长,凋亡指数逐渐降低,由6- h的32.3%降至7 d的5%(P<0.05);细胞色素C和caspase 3随治疗时间延长表达逐渐减少;电镜可见典型的肝细胞凋亡随治疗时间的延长明显改善。结论　SNMC对小鼠FLF有明显的保护作用,其机制可能是抑制各种因素所介导的炎症反应及通过稳定线粒体膜抑制细胞色素     

Expressions of apoptosis-regulating factors in bovine retained placenta

The aim of the present study was to evaluate the relationship between the retention of fetal membranes (RFM) and apoptosis of the cells in fetal membranes. The present study investigated mRNA and protein expressions of apoptosis-regulating factors: FAS, cellular FLICE-like inhibiting protein (cFLIP), BAX, BCL2, caspase-8 (CASP8), and CASP3 in fetal membranes. Placentomes were manually collected from the uterus immediately after parturition and classified into two groups (RFM; n = 8 and non-RFM; n = 8) according to whether placental membranes were expelled or not within 12 h after delivery. FAS mRNA expression in maternal placental tissue was less in RFM cows than in non-RFM cows (P < 0.05). cFLIP mRNA expression in maternal and fetal placental tissue was greater in RFM cows than in non-RFM cows (P < 0.05). CASP3 mRNA expression in maternal placental tissue was greater in RFM cows than in non-RFM cows (P < 0.05). However, the protein expressions of FAS, cFLIP and cleaved CASP3 were not significantly different between the two groups. mRNA and protein expressions of BAX, BCL2 and CASP8 were also not significantly different between the two groups. In the immunohistochemical study, single-stranded DNA, which appears specifically in the apoptotic cells, was mainly found in the maternal placenta of non-RFM cows. Together these results suggest that RFM occurs at least in part due to a dysfunctional apoptotic process caused by the inhibition of FAS expression in the maternal placenta, and the increase of cFLIP expression in the maternal and fetal placenta.     

尿多酸肽通过调节caspase家族诱导多发性骨髓瘤细胞U266凋亡的实验研究

目的探讨尿多酸肽抑制多发性骨髓瘤（MM）细胞株U266增值及其机制。 方法采用四甲基偶氮唑（MTT）比色法计算不同尿多酸肽浓度（1.0、2.0、3.0、4.0、5.0 mg/g）对U266细胞生长的抑制率,Hoechst33258染色观察尿多酸肽作用后的细胞凋亡情况,Annexin-V/碘化丙啶（PI）检测尿多酸肽作用6、12、24 h后与对照组细胞（加细胞未加药物）的细胞凋亡率。使用Western-blotting法检测caspase 8、caspase 3及其激活物在U266细胞株经尿多酸肽（4 mg/g）作用6、12、24 h后的表达改变。 结果随着尿多酸肽浓度提高,U266细胞抑制率显著上升（F= 17.276,P< 0.001）。经尿多酸肽作用后,Hoechst33258荧光染色提示细胞核浓集及出现凋亡小体。Annexin-V/PI分析显示,尿多酸肽处理6、12、24 h后细胞凋亡率显著高于对照组细胞[（5.53 ± 0.28）%、（9.43 ± 1.78）%、（21.50 ± 2.45）%、（3.03 ± 0.11）%,F= 12.242,P<0.001]。同时,随着尿多酸肽作用时间延长,pro-caspase 8、pro-caspase 3表达明显下降（F= 18.241,P<0.001;F= 4.924,P= 0.005）,而active-caspase 8、active-caspase 3表达明显上升（F= 22.322,P<0.001;F= 6.213,P= 0.002）。 结论尿多酸肽可抑制U266细胞增殖,且可能通过caspase凋亡途径在其中起主要作用。     

丙戊酸钠诱导K562细胞凋亡的机制探讨

目的 探讨丙戊酸钠(VPA)诱导K562细胞凋亡的可能机制.方法 将K562细胞分为经VPA 2.0mmol/L处理的实验组(A组)和正常对照组(B组),分别培养24、48、72 h.流式细胞术检测细胞凋亡率和线粒体膜电位改变,分光光度法检测半胱氨酸天门冬氨酸蛋白酶(Caspase)8、Caspase-9蛋白活性.结果 A组细胞凋亡率、细胞线粒体跨膜电位破坏率呈时问依赖性地增加,且明显高于B组(P<0.05);与B组相比,A组不同时间的Caspase-8、Caspase-9活性均上调(P<0.05).结论 VPA诱导K562细胞凋亡的机制可能与线粒体跨膜电位崩溃或死亡途径有关.     

原花青素对大鼠脑缺血再灌注损伤Caspase-3表达和神经元凋亡的影响

目的探讨原花青素（PC）对脑缺血再灌注损伤大鼠Caspase-3表达和神经元凋亡的影响。方法40只大鼠随机分为假手术组、缺血再灌注组、PC低剂量治疗组和PC高剂量治疗组,线栓法建立局灶性脑缺血再灌注模型。各组于缺血90min再灌注24h用免疫组化法观察大鼠额顶部皮质Caspase-3蛋白表达,采用TUNEL法检测神经细胞凋亡,并进行TTC染色和HE染色观察脑梗死体积及病理形态学变化。结果缺血再灌注组与假手术组比较,Caspase-3表达增加,凋亡细胞明显增加;PC治疗组与缺血再灌注组比较均显著减少Caspase-3表达,减少凋亡细胞,高、低剂量组之间差异有统计学意义（P〈0．05）。PC治疗组脑组织缺血损伤病理学改变均明显轻于缺血再灌注组,PC高剂量治疗组缺血改变亦轻于低剂量治疗组。PC治疗组脑梗死体积均较缺血再灌注组减小,且高、低剂量组之间差异具有统计学意义（P〈0．05）。结论PC对缺血再灌注脑损伤具有保护作用,其机制可能与通过减少Caspase-3表达,抗凋亡有关。