Peroxiredoxin V保护HT22小鼠海马神经细胞抵抗NO诱导的细胞凋亡

Peroxiredoxin V(Prx V)是过氧化物酶peroxiredoxins家族中的一员,在神经细胞中含量丰富,具有通过清除细胞内活性氧(reactive oxygen species,ROS)和过氧亚硝酸盐抑制氧化应激诱导的细胞凋亡的作用。过量的一氧化氮(nitric oxide,NO)具有较强的神经毒性,可引起小胶质细胞炎性反应,诱导神经细胞凋亡从而引发神经退行性疾病,而且可诱导神经小胶质细胞Prx V的表达,参与小胶质细胞的活性调控过程。但是,NO诱导的海马神经细胞凋亡过程中Prx V的作用尚不清楚。该研究利用硝普化钠(sodium nitroprusside dihydrate,SNP)作为NO供体,检测了NO诱导的HT22小鼠海马神经细胞的凋亡及对Prx V蛋白表达的影响。结果显示,SNP诱导的HT22细胞凋亡呈现时间、浓度依赖性;并特异性地抑制了Prx V的表达,致使细胞内ROS水平升高,激活线粒体依赖的经典凋亡途径,导致HT22细胞的凋亡。该研究结果揭示,NO通过抑制细胞内Prx V的表达导致细胞内ROS水平升高,最终诱导HT22细胞发生凋亡的机制,为保护NO诱导的神经细胞凋亡提供了新的理论依据。     

过氧化物酶V在顺铂诱导HepG2肝癌细胞凋亡过程中的调控作用

过氧化物酶V(peroxiredoxin V, Prx V)是过氧化物酶家族(peroxiredoxins, Prxs)中的一员,具有清除细胞内活性氧(reactive oxygen species, ROS)的功能。该文主要阐明了Prx V在顺铂(cisplatin, CDDP)诱导Hep G2人肝癌细胞凋亡过程中的调控作用。该研究利用顺铂处理Hep G2肝癌细胞,通过荧光显微照相、流式细胞术、蛋白质免疫印迹分析等方法检测细胞内活性氧(ROS)水平、细胞凋亡情况以及凋亡相关蛋白水平。研究结果表明,顺铂可引起细胞内的ROS水平升高导致细胞凋亡,同时造成细胞内Prx V蛋白质表达水平下降。利用慢病毒载体过量表达Prx V基因后,顺铂诱导的Prx V过量表达型HepG2细胞凋亡率明显低于Mock组,同时促凋亡蛋白cleavage-Caspase-3、Bad、cleavage-PARP表达水平也明显被下调,说明Prx V在顺铂诱导HepG2细胞凋亡过程中具有一定的抑制作用。该研究初步探究了Prx V在顺铂诱导的HepG2肝癌细胞凋亡过程中的调控作用,为肝癌的治疗研究提供了新的思路和治疗靶点。     

氧化型胆固醇诱导血管细胞凋亡的机制

氧化型胆固醇（Ch—Ox）能诱导血管细胞凋亡,它是氧化低密度脂蛋白诱导细胞凋亡的主要活性成分之一,在动脉粥样硬化的形成过程中起重要作用。本文综合目前Ch—Ox的细胞毒性作用的研究进展,讨论了Ch-Ox诱导细胞凋亡的可能机制,并对凋亡的两种可能途径及信号转导进行分析,认为Ch-Ox通过线粒体途径诱导细胞凋亡已得到大量研究结果的证明;而通过死亡受体途径的可能性仍有待于进一步研究;胞内钙离子浓度的升高是Ch—Ox诱导细胞凋亡的早期信号转导事件;活性氧在Ch-Ox诱导细胞凋亡过程中也可能作为第二信使发挥重要作用。     

麦芽酚对活性氧损伤人神经瘤细胞的保护作用

以人神经瘤细胞株 (SH SY5Y)为材料 ,使用过氧化氢 (H2 O2 )产生过量活性氧诱导SH SY5Y细胞株进入氧化应激状态 .研究麦芽酚对过量活性氧造成的SH SY5Y细胞株氧化损伤的保护作用 .分析活性氧对细胞膜蛋白和DNA的损伤 ,细胞线粒体功能变化 ,白介素 6 (IL 6 )的表达变化以及细胞核因子κB(NF κB)的激活 .结果显示 ,2mmol L麦芽酚保护细胞 2h后 ,对细胞膜蛋白和DNA的损伤均有明显的保护作用 ,减少了膜蛋白的氧化和细胞DNA片段化的形成 ,细胞线粒体功能损伤减小 ,细胞表达的IL 6减少 ,被激活的NF κB水平同时降低 .结果证明 ,麦芽酚可以有效保护活性氧对神经细胞的氧化损伤 ,维持细胞的正常生理功能     

Sestrin2通过抑制砷化物诱导的氧化应激反应发挥拮抗细胞凋亡的保护性作用

目的:探讨Sestrin2在砷化物诱导细胞凋亡反应中的作用及机制。方法:体外培养人肝癌细胞HepG2,以砷化物为刺激源,用免疫印迹和RT-PCR方法检测Sestrin2在砷化物刺激HepG2细胞前后的表达水平差异;用流式细胞术检测敲低Sestrin2前后以及抑制氧化应激反应前后细胞凋亡水平变化情况;用活性氧(ROS)检测试剂盒分析敲低Sestrin2前后细胞在砷化物刺激后的氧化应激水平变化情况。结果:砷化物刺激HepG2细胞后Sestrin2表达水平显著上调;敲低HepG2细胞中Sestrin2表达水平后,细胞凋亡水平明显升高,说明Sestrin2的诱导表达是砷化物诱导细胞凋亡反应中的保护性事件;在敲低Sestrin2表达水平后,砷化物诱导的ROS产生效应和氧化应激反应程度明显加剧;抗氧化剂NAC能够显著逆转Sestrin2对细胞凋亡的保护性效应。结论:Sestrin2在砷化物诱导细胞凋亡反应中可通过抑制ROS产生而发挥拮抗细胞凋亡的保护性作用。     

活性氧对NF-κB活性及JNK信号通路的调节

活性氧（ROS）是生物体有氧代谢过程中产生的一类活性含氧化合物的总称,机体细胞可通过多种途径维持ROS产生与降解的动态平衡。研究表明,活性氧可作为第二信使调节与细胞增殖、分化、凋亡相关的信号转导通路。c-JunN端激酶（JNK）通路可以介导氧化应激、细胞因子、紫外照射等引起的细胞凋亡。另外,κ基因结合核因子（NF-κB）是氧化应激调节的靶因子之一,同样也能诱导促进细胞内的氧化应激反应,还可通过活性氧蓄积抑制JNK的激活。简要综述活性氧对NF-κB和JNK信号通路的调节。     

绞股蓝总皂苷对光老化人皮肤成纤维细胞凋亡及Caspase-3信号通路的影响

目的:探讨绞股蓝总皂苷(Gyp)对光老化人皮肤成纤维细胞(HSF细胞)凋亡以及Caspase-3信号通路的影响。方法:分别以80、160、320 mg/d剂量的Gyp生理盐水溶液灌胃大鼠7d后取血并分离血清,长波紫外线(UVA)照射方法(照射剂量36 J/cm3)构建光老化HSF细胞模型以得到低剂量组、中剂量组、高剂量组,同时以空白对照组(未照射细胞)、UVA模型组、正常组为对照。UVA诱导的细胞活性氧表达采用二氯荧光素(DCF)法测定,细胞凋亡情况采用TUNEL法测定,HSF细胞活性采用四甲基偶氮唑盐微量酶反应比色法(MTT法)测定,Bax、Bcl-2、Caspase-3基因和蛋白表达分别采用反转录-聚合酶链反应(RT-PCR)和Western-blotting方法进行测定。结果:与空白对照组比较,其余5组的OD值、HSF细胞凋亡数、活性氧(平均荧光强度)、活性氧水平、Bax、Bcl-2、Caspase-3 mRNA及蛋白表达水平差异具有统计学意义(P0.05);与UVA模型组和正常组比较,低、中、高剂量组OD值、HSF细胞凋亡数、活性氧(平均荧光强度)、活性氧水平、Bax、Bcl-2、Caspase-3 mRNA及蛋白表达水平差异具有统计学意义(P0.05);低、中、高剂量组随着剂量增加OD值、Bcl-2mRNA和蛋白表达水平逐渐升高,细胞凋亡数、活性氧(平均荧光强度)、活性氧水平、Bax、Caspase-3 mRNA和蛋白表达水平逐渐降低(P0.05)。结论:Gyp通过抑制细胞内活性氧的产生以及Bax的表达,以及激活Bcl-2、Caspase-3信号通路而逆转UVA诱导的HSF细胞凋亡,进而延缓HSF细胞的光老化现象。     

活性氧诱导细胞凋亡

细胞凋亡是细胞主动的衰老和死亡方式。细胞凋亡过程极其复杂,其生化机制还不十分清楚。用活性氧如H_2O_2、ONOO及脂质过氧化物等可直接诱导某些细胞发生凋亡,抗氧化剂对细胞凋亡有抑制作用。细胞内产生活性氧的部位主要是线粒体电子传递链、黄嘌呤—黄嘌呤氧化酶途径、磷脂酶A_2激活的花生四烯酸代谢途径及精氨酸-NO合成酶途径。外源性活性氧或通过内源性活性氧的生成,导致细胞内氧化还原状态的失衡,诱导某些基因的表达,引起凋亡。     

麻欠精油对脂多糖诱导的THP-1细胞氧化应激的影响

本研究主要探讨麻欠精油对脂多糖(LPS)诱导的THP-1细胞氧化应激的影响。溶剂对照、地塞米松或不同浓度的麻欠精油预处理THP-1细胞后,再用LPS培养24 h,用DCFH-DA荧光探针标记细胞后流式检测细胞内活性氧ROS;用FITC Annexin V/PI双染法流式检测细胞凋亡;用Griess试剂测定NO;用比色法检测总超氧化物歧化酶(SOD);用Western Blot法检测NADPH p47 phox的表达。结果发现麻欠精油处理组与溶剂对照组相比,LPS诱导的ROS和NO水平显著降低、SOD水平显著增加、NADPH p47 phox蛋白表达减低,细胞凋亡降低。以上实验结果表明麻欠精油对LPS诱导的THP-1细胞的氧化应激有明显抑制作用并对细胞凋亡有保护作用。     

活性氧:从毒性分子到信号分子--活性氧与细胞的增殖、分化和凋亡及其信号转导途径

活性氧(reactive oxygen species,ROS)是生物体有氧代谢产生的一类活性含氧化合物的总称,主要包括O2·-、H2O2、·OH等,机体细胞通过多种途径维持ROS产生与消解的动态平衡。近年的研究揭示ROS参与细胞正常的生理过程,与细胞的增殖、分化及凋亡密切相关。不同刺激诱导细胞产生的内源性ROS可作为第二信使,通过改变氧化还原状态调节增殖、分化和凋亡相关的信号转导通路中多种靶分子的活性,最终决定细胞的命运。     

Cytoprotective Effect of Ferritin H in Renal Ischemia Reperfusion Injury

Oxidative stress is a major contributor to kidney injury following ischemia reperfusion. Ferritin, a highly conserved iron-binding protein, is a key protein in the maintenance of cellular iron homeostasis and protection from oxidative stress. Ferritin mitigates oxidant stress by sequestering iron and preventing its participation in reactions that generate reactive oxygen species. Ferritin is composed of two subunit types, ferritin H and ferritin L. Using an in vivo model that enables conditional tissue-specific doxycycline-inducible expression of ferritin H in the mouse kidney, we tested the hypothesis that an increased level of H-rich ferritin is renoprotective in ischemic acute renal failure. Prior to induction of ischemia, doxycycline increased ferritin H in the kidneys of the transgenic mice nearly 6.5-fold. Following reperfusion for 24 hours, induction of neutrophil gelatinous-associated lipocalin (NGAL, a urine marker of renal dysfunction) was reduced in the ferritin H overexpressers compared to controls. Histopathologic examination following ischemia reperfusion revealed that ferritin H overexpression increased intact nuclei in renal tubules, reduced the frequency of tubular profiles with luminal cast materials, and reduced activated caspase-3 in the kidney. In addition, generation of 4-hydroxy 2-nonenal protein adducts, a measurement of oxidant stress, was decreased in ischemia-reperfused kidneys of ferritin H overexpressers. These studies demonstrate that ferritin H can inhibit apoptotic cell death, enhance tubular epithelial viability, and preserve renal function by limiting oxidative stress following ischemia reperfusion injury.     

The many faces of the octahedral ferritin protein

Iron is an essential trace nutrient required for the active sites of many enzymes, electron transfer and oxygen transport proteins. In contrast, to its important biological roles, iron is a catalyst for reactive oxygen species (ROS). Organisms must acquire iron but must protect against oxidative damage. Biology has evolved siderophores, hormones, membrane transporters, and iron transport and storage proteins to acquire sufficient iron but maintain iron levels at safe concentrations that prevent iron from catalyzing the formation of ROS. Ferritin is an important hub for iron metabolism because it sequesters iron during times of iron excess and releases iron during iron paucity. Ferritin is expressed in response to oxidative stress and is secreted into the extracellular matrix and into the serum. The iron sequestering ability of ferritin is believed to be the source of the anti-oxidant properties of ferritin. In fact, ferritin has been used as a biomarker for disease because it is synthesized in response to oxidative damage and inflammation. The function of serum ferritin is poorly understood, however serum ferritin concentrations seem to correlate with total iron stores. Under certain conditions, ferritin is also associated with pro-oxidant activity. The source of this switch from anti-oxidant to pro-oxidant has not been established but may be associated with unregulated iron release from ferritin. Recent reports demonstrate that ferritin is involved in other aspects of biology such as cell activation, development, immunity and angiogenesis. This review examines ferritin expression and secretion in correlation with anti-oxidant activity and with respect to these new functions. In addition, conditions that lead to pro-oxidant conditions are considered.     

Ferritin and ferritin isoforms II: protection against uncontrolled cellular proliferation, oxidative damage and inflammatory processes

Ferritin is a major iron storage protein involved in the regulation of iron availability. Each ferritin molecule comprises 24 subunits. Various combinations of H-subunits and L-subunits make up the 24-subunit protein structure and these ferritin isoforms differ in their H-subunit to L-subunit ratio, as well as in their metabolic properties. Ferritin is an acute-phase protein and its expression is up-regulated in conditions such as uncontrolled cellular proliferation, in any condition marked by excessive production of toxic oxygen radicals, and by infectious and inflammatory processes. Under such conditions ferritin up-regulation is predominantly stimulated by increased reactive oxygen radical production and by cytokines. The major function of ferritin in these conditions is to reduce the bio-availability of iron in order to stem uncontrolled cellular proliferation and excessive production of reactive oxygen radicals. Ferritin is not, however, indiscriminately up-regulated in these conditions as a marked shift towards a predominance in H-subunit rich ferritins occurs. Preliminary indications are that, while the L-subunit primarily fulfils the conventional iron storage role, the H-subunit functions primarily as rapid regulator of iron availability, and perhaps indirectly as regulator of other cellular processes. It is suggested that the optimum differential expression of the two subunits differ for different cells and under different conditions and that the expression of appropriate isoferritins offers protection against uncontrolled cellular proliferation, oxidative stress and against side effects of infectious and inflammatory conditions.     

Platycodin D protects cortical neurons against oxygen-glucose deprivation/reperfusion in neonatal hypoxic-ischemic encephalopathy

Neonatal hypoxic-ischemic encephalopathy is one of the leading causes of death in infants. Increasing evidence indicates that oxidative stress and apoptosis are major contributors to hypoxic-ischemic injury and can be used as particularly promising therapeutic targets. Platycodin D (PLD) is a triterpenoid saponin that exhibits antioxidant properties. The aim of this study was to evaluate the effects of PLD on hypoxic-ischemic injury in primary cortical neurons. We found that oxygen-glucose deprivation/reperfusion (OGD/R) induced inhibition of cell viability and cytotoxicity, which were attenuated by PLD treatment. PLD treatment inhibited oxidative stress induced by OGD/R, which was evidenced by the reduced level of reactive oxygen species and increased activities of catalase, superoxide dismutase, and glutathione peroxidase. Histone-DNA enzyme-linked immunosorbent assay revealed that apoptosis was significantly decreased after PLD treatment in OGD/R-treated cortical neurons. The increased bax expression and decreased bcl-2 expression induced by OGD/R were reversed by PLD treatment. Furthermore, PLD treatment caused the activation of the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) pathway in OGD/R-stimulated cortical neurons. Suppression of this pathway blocked the protective effects of PLD on OGD/R-induced cell injury. These findings suggested that PLD executes its protective effects on OGD/R-induced cell injury via regulating the PI3K/Akt/mTOR pathway in cortical neurons.