In recent years, adenosine tri-phosphate （ATP） has been reported to exist in apoplasts of plant cells as a signal molecule. Extracellular ATP （eATP） plays important roles in plant growth, development, and stress t...In recent years, adenosine tri-phosphate （ATP） has been reported to exist in apoplasts of plant cells as a signal molecule. Extracellular ATP （eATP） plays important roles in plant growth, development, and stress tolerance. Here, extra- cellular ATP was found to promote stomatal opening of Arabidopsis thaliana in light and darkness. ADP, GTP, and weakly hydrolyzable ATP analogs （ATPγS, Bz-ATP, and 2meATP） showed similar effects, whereas AMP and adenosine did not affect stomatal movement. Apyrase inhibited stomatal opening. ATP-promoted stomatal opening was blocked by an NADPH oxidase inhibitor （diphenylene iodonium） or deoxidizer （dithiothreitol）, and was impaired in null mutant of NADPH ox- idase （atrbohD/F）. Added ATP triggered ROS generation in guard cells via NADPH oxidase. ATP also induced Ca^2＋ influx and H ＋ efflux in guard cells. In atrbohD/F, ATP-induced ion flux was strongly suppressed. In null mutants of the heterotrimeric G protein α subunit, ATP-promoted stomatal opening, cytoplasmic ROS generation, Ca^2＋ influx, and ^H＋ efflux were all sup- pressed. These results indicated that eATP-promoted stomatal opening possibly involves the heterotrimeric G protein, ROS, cytosolic Ca^2＋, and plasma membrane H＋-ATPase.展开更多
Accumulative evidence has shown the adverse effects of a geomagnetic field shielded condition, so called a hypomagnetic field （HMF）, on the metabolic processes and oxidative stress in animals and cells. However, the...Accumulative evidence has shown the adverse effects of a geomagnetic field shielded condition, so called a hypomagnetic field （HMF）, on the metabolic processes and oxidative stress in animals and cells. However, the underlying mechanism remains unclear. In this study, we evaluate the role of HMF on the regulation of cellular reactive oxygen species （ROS） in human neuroblastoma SH-SY5Y cells. We found that HMF exposure led to ROS decrease, and that restoring the decrease by additional H2O2 rescued the HMF-enhanced cell proliferation. The measurements on ROS related indexes, including total anti-oxidant capacity, H2O2 and superoxide anion levels, and superoxide dismutase （SOD） activity and expres- sion, indicated that the HMF reduced H2O2 production and inhibited the activity of CuZn-SOD. Moreover, the HMF accelerated the denaturation of CuZn-SOD as well as enhanced aggregation of CuZn-SOD protein, in vitro. Our findings indicate that CuZn-SOD is able to response to the HMF stress and suggest it a mediator of the HMF effect.展开更多
In plants, the chloroplast is the main reactive oxygen species （ROS） producing site under high light stress. Catalase （CAT）, which decomposes hydrogen peroxide （H2O2）, is one of the controlling enzymes that main...In plants, the chloroplast is the main reactive oxygen species （ROS） producing site under high light stress. Catalase （CAT）, which decomposes hydrogen peroxide （H2O2）, is one of the controlling enzymes that maintains leaf redox homeostasis. The catalase mutants with reduced leaf catalase activity from different plant species exhibit an H2O2-induced leaf cell death phenotype. This phenotype was differently affected by light intensity or photoperiod, which may be caused by plant species, leaf redox status or growth conditions. In the rice CAT mutant nitric oxide excess 1 （noe1）, higher H2O2 levels induced the generation of nitric oxide （NO） and higher S-nitrosothiol （SNO） levels, suggesting that NO acts as an important endogenous mediator in H2O2-induced leaf cell death. As a free radical, NO could also react with other intracellular and extracellular targets and form a series of related molecules, collectively called reactive nitrogen species （RNS）. Recent studies have revealed that both RNS and ROS are important partners in plant leaf cell death. Here, we summarize the recent progress on H2O2-induced leaf cell death and the crosstalk of RNS and ROS signals in the plant hypersensitive response （HR）, leaf senescence, and other forms of leaf cell death triggered by diverse environmental conditions.展开更多
Abstract Objective To investigate the toxic effects of decabromodiphenyl ethane （DBDPE）, used as an alternative to decabromodiphenyl ether in vitro. Methods HepG2 cells were cultured in the presence of DBDPE at vari...Abstract Objective To investigate the toxic effects of decabromodiphenyl ethane （DBDPE）, used as an alternative to decabromodiphenyl ether in vitro. Methods HepG2 cells were cultured in the presence of DBDPE at various concentrations （3.125-100.0 mg/L） for 24, 48, and 72 h respectively and the toxic effect of DBDPE was studied. Results As evaluated by the 3-（4,5-dimethylthiazol-2-yl）-2,5-diphenyl tetrazolium bromide and lactate dehydrogenase assays and nuclear morphological changes, DBDPE inhibited HepG2 viability in a time- and dose-dependent manner within a range of 12.5 mg/L to 100 mg/L and for 48 h and 72 h. Induction of apoptosis was detected at 12.5-100 mg/L at 48 h and 72 h by propidium iodide staining, accompanied with overproduction of reactive oxygen species （ROS）. Furthermore, N-acetyI-L-cysteine, a widely used ROS scavenger, significantly reduced DBDPE-induced ROS levels and increased HepG2 cells viability. Conclusion DBDPE has cytotoxic and anti-proliferation effect and can induce apoptosis in which ROS plays an important role展开更多
Using forward and reverse genetics and global gene expression analyses, we explored the crosstalk between the IKB kinase β （IKKβ） and the transforming growth factor β （TGFβ） signaling pathways. We show that in...Using forward and reverse genetics and global gene expression analyses, we explored the crosstalk between the IKB kinase β （IKKβ） and the transforming growth factor β （TGFβ） signaling pathways. We show that in vitro ablation of Ikkβ in fibroblasts led to progressive ROS accumulation and TGFβ activation, and ultimately accelerated cell migration, fibroblast-myofibroblast transformation and senescence. Mechanistically, the basal IKKβ activity was required for anti-oxidant gene expression and redox homeostasis. Lacking this activity, IKKβ-null cells showed ROS accumulation and activation of stress-sensitive transcription factor AP-1/c- Jun. AP-1/c-Jun activation led to up-regulation of the Tgfβ2 promoter, which in turn further potentiated intracellular ROS through the induction of NADPH oxidase （NOX）. These data suggest that by blocking the autocrine amplification of a ROS-TGFβ loop IKKβ plays a crucial role in the prevention of fibroblast-myofibroblast transformation and senescence.展开更多
Cellular and mitochondrial damage can be caused by labile iron pool (LIP) and mediated by reactive oxygen species (ROS). Livers of the thalassemias have highly increased levels of LIP and ROS. Green tea extract (GTE) ...Cellular and mitochondrial damage can be caused by labile iron pool (LIP) and mediated by reactive oxygen species (ROS). Livers of the thalassemias have highly increased levels of LIP and ROS. Green tea extract (GTE) and epigallocatechin 3-gallatte (EGCG) can potentially protect liver inflammation, fibrosis and cancer due to their anti-oxidative and iron-chelating activities. We studied the effects of GTE and EGCG on intracellular LIP and ROS, and mitochondrial membrane potential (ΔΨm) in mouse hepatocyte and HepG2 cell cultures using specific fluorescent techniques. Treatment with GTE (12.5 - 25 mg/dl) and EGCG (25 - 50 μM) significantly lowered levels of ΔΨm in the mouse hepatocytes;however, combined treatment of 25 μM DFP with GTE and EGCG did not enhance the decrease of hepatic ΔΨm. The results showed that GTE and EGCG effectively removed the intracellular LIP and ROS, and relieved the mitochondria membrane collapse of the liver cells, suggesting a hepatoprotective effect of green tea extract and EGCG in the hepatocytes with iron overload. Their actions might be related to iron-chelating and free radical-scavenging capacities. Whether the effects can improve iron overload and oxidative stress in thalassemia patients remains to be seen upon further examination.展开更多
Magnesium-aluminum layered double hydroxide （Mg/ALLDH） nanoparticles have strong potential application as drug delivery systems because of their low toxicity and suitable biocompatibility. However, few studies have ...Magnesium-aluminum layered double hydroxide （Mg/ALLDH） nanoparticles have strong potential application as drug delivery systems because of their low toxicity and suitable biocompatibility. However, few studies have described the morphological effects of these hydroxides on nerve cells. The present study compares the oxidative stress induced by different concentrations （i.e., 0, 50, 100, 200, 400, and 800 μg/mL） of sand flower and flake nano-Mg/ AI-LDHs in mouse neuroblastoma cells （N2a） when these cells were exposed for 24 and 48 h. Cell viability was detected by MTT assay, and production of reactive oxygen species （ROS）, glutathione （GSH）, and malondialdehyde （MDA） were monitored to evaluate oxidative damage. Results suggested that sand flower nano-LDHs, at the appropriate concentrations （less than 200 μg/mL）, especially those of about 100-200 nm in size, induce no harmful effects on N2a cells.展开更多
The growth of seedlings of Townsville sytlo (Stylosanthes humilis H.B.K.) is inhibited by aluminium (Al) ions, their elongation being re-covered with sodium selenate at 1.0 μM. Methyl viologen and hydrogen peroxide, ...The growth of seedlings of Townsville sytlo (Stylosanthes humilis H.B.K.) is inhibited by aluminium (Al) ions, their elongation being re-covered with sodium selenate at 1.0 μM. Methyl viologen and hydrogen peroxide, reactive oxy-gen species (ROS)-generating compounds, also inhibited seedling elongation and again growth was relieved by selenate. Selenate, thus, seemed to be operating as a ROS quencher, since N-acetylcysteine (NAC), an antioxidant com-pound, also stimulated largely the growth of Al-inhibited seedlings. At a higher concentra-tion (0.1 mM), however, selenate inhibited seed-ling growth and elongation was recovered by NAC. Ethylene production by selenate plus NAC-treated seedlings was very higher and thus the gaseous hormone was not responsible for the seedling growth inhibition caused by sele-nate. Hence, it seems that at high levels sele-nate operates as a ROS-generating compound whose effects were counteracted by NAC. It can be deduced that, at low concentration, sele-nates behave as a ROS quencher and at high level as a ROS-promoting species.展开更多
Objective： This work aimed to study the inhibitory effect and the related mechanism of metformin （MET） on the proliferation of human hepatoma HepG2 cells. Methods： Human hepatoma HepG2 cells were treated with MET ...Objective： This work aimed to study the inhibitory effect and the related mechanism of metformin （MET） on the proliferation of human hepatoma HepG2 cells. Methods： Human hepatoma HepG2 cells were treated with MET （0, 2, 10, and 50 mM）. The inhibitory effect of MET on the proliferation of HepG2 cells was determined by MTT method. The apoptosis of HepG2 cells was detected by flow cytornetry. The expression of cyclin D1 in HepG2 cells was examined by Western blot. ROS-DHE fluorescence probe was used to stain the reactive oxygen species （ROS） generated by HepG2 cells after treat- ment. Results： MET could inhibit the proliferation of HepG2 cells in a dose and time dependent manner. MET promoted the apoptosis of HepG2 cells. In addition, MET suppressed the expression of cell cycle protein cyclin D1 and induced the produc- tion of ROS in HepG2 cells. Conclusion： MET can inhibit the proliferation of human hepatoma HepG2 cells and induce cell apoptosis. Meanwhile, MET has the ability to decrease the expression of cyclin D1 and induce ROS generation, which may be involved in the mechanism of inhibiting hepatoma cells proliferation.展开更多
背景:血管内皮细胞衰老、凋亡与再生的平衡对正常血管的功能维持具有极其重要的作用。而线粒体是机体细胞内的重要细胞器,除了合成 ATP 为细胞提供能量外,还控制细胞程序性死亡、以及衰老等多种病理生理的代谢过程。目的:通过检测脐静...背景:血管内皮细胞衰老、凋亡与再生的平衡对正常血管的功能维持具有极其重要的作用。而线粒体是机体细胞内的重要细胞器,除了合成 ATP 为细胞提供能量外,还控制细胞程序性死亡、以及衰老等多种病理生理的代谢过程。目的:通过检测脐静脉内皮细胞传代过程中线粒体膜电位与活性氧的改变及其相互关系,从而探讨细胞衰老过程中所产生的功能障碍。方法:体外培养人脐静脉内皮细胞,选取传代过程中的第 2,4,6,8 代细胞,采用流式细胞术检测细胞线粒体膜电位及活性氧变化。选取第 2,8 代细胞行透射电镜检查,观察正常及衰老细胞超微结构的改变。结果与结论:传代衰老过程中,血管内皮细胞线粒体膜电位逐代降低,而胞内活性氧则出现由增加转而降低的过程。传代后期血管内皮细胞同早期内皮细胞相比,线粒体及内质网明显减少。说明内皮细胞在传代导致的复制性衰老过程中,线粒体膜电位降低,线粒体受损。而在早期传代过程中线粒体轻度受损,而活性氧产生增加,但在线粒体严重受损、功能严重退化过程中,活性氧产生降低。展开更多
基金This work was supported by the National Science Foundation of China，the Program for New Century Excellent Talents in University，the State Key Laboratory of Plant Cell and Chromosome Engineering，No conflict of interest declared
文摘In recent years, adenosine tri-phosphate （ATP） has been reported to exist in apoplasts of plant cells as a signal molecule. Extracellular ATP （eATP） plays important roles in plant growth, development, and stress tolerance. Here, extra- cellular ATP was found to promote stomatal opening of Arabidopsis thaliana in light and darkness. ADP, GTP, and weakly hydrolyzable ATP analogs （ATPγS, Bz-ATP, and 2meATP） showed similar effects, whereas AMP and adenosine did not affect stomatal movement. Apyrase inhibited stomatal opening. ATP-promoted stomatal opening was blocked by an NADPH oxidase inhibitor （diphenylene iodonium） or deoxidizer （dithiothreitol）, and was impaired in null mutant of NADPH ox- idase （atrbohD/F）. Added ATP triggered ROS generation in guard cells via NADPH oxidase. ATP also induced Ca^2＋ influx and H ＋ efflux in guard cells. In atrbohD/F, ATP-induced ion flux was strongly suppressed. In null mutants of the heterotrimeric G protein α subunit, ATP-promoted stomatal opening, cytoplasmic ROS generation, Ca^2＋ influx, and ^H＋ efflux were all sup- pressed. These results indicated that eATP-promoted stomatal opening possibly involves the heterotrimeric G protein, ROS, cytosolic Ca^2＋, and plasma membrane H＋-ATPase.
文摘Accumulative evidence has shown the adverse effects of a geomagnetic field shielded condition, so called a hypomagnetic field （HMF）, on the metabolic processes and oxidative stress in animals and cells. However, the underlying mechanism remains unclear. In this study, we evaluate the role of HMF on the regulation of cellular reactive oxygen species （ROS） in human neuroblastoma SH-SY5Y cells. We found that HMF exposure led to ROS decrease, and that restoring the decrease by additional H2O2 rescued the HMF-enhanced cell proliferation. The measurements on ROS related indexes, including total anti-oxidant capacity, H2O2 and superoxide anion levels, and superoxide dismutase （SOD） activity and expres- sion, indicated that the HMF reduced H2O2 production and inhibited the activity of CuZn-SOD. Moreover, the HMF accelerated the denaturation of CuZn-SOD as well as enhanced aggregation of CuZn-SOD protein, in vitro. Our findings indicate that CuZn-SOD is able to response to the HMF stress and suggest it a mediator of the HMF effect.
基金supported by grants from the National Natural Science Foundation of China (31171514, 30600407)the Ministry of Science and Technology of China (2009CB118506)+2 种基金an international exchange grant provided by the National Natural Science Foundation of Chinathe Royal Society of Edinburgh (30811130222)supported by a BBSRC grant BB/D0118091/1
文摘In plants, the chloroplast is the main reactive oxygen species （ROS） producing site under high light stress. Catalase （CAT）, which decomposes hydrogen peroxide （H2O2）, is one of the controlling enzymes that maintains leaf redox homeostasis. The catalase mutants with reduced leaf catalase activity from different plant species exhibit an H2O2-induced leaf cell death phenotype. This phenotype was differently affected by light intensity or photoperiod, which may be caused by plant species, leaf redox status or growth conditions. In the rice CAT mutant nitric oxide excess 1 （noe1）, higher H2O2 levels induced the generation of nitric oxide （NO） and higher S-nitrosothiol （SNO） levels, suggesting that NO acts as an important endogenous mediator in H2O2-induced leaf cell death. As a free radical, NO could also react with other intracellular and extracellular targets and form a series of related molecules, collectively called reactive nitrogen species （RNS）. Recent studies have revealed that both RNS and ROS are important partners in plant leaf cell death. Here, we summarize the recent progress on H2O2-induced leaf cell death and the crosstalk of RNS and ROS signals in the plant hypersensitive response （HR）, leaf senescence, and other forms of leaf cell death triggered by diverse environmental conditions.
基金supported by the NSFC(No.20877102)"973"project(No.2010CB933904)
文摘Abstract Objective To investigate the toxic effects of decabromodiphenyl ethane （DBDPE）, used as an alternative to decabromodiphenyl ether in vitro. Methods HepG2 cells were cultured in the presence of DBDPE at various concentrations （3.125-100.0 mg/L） for 24, 48, and 72 h respectively and the toxic effect of DBDPE was studied. Results As evaluated by the 3-（4,5-dimethylthiazol-2-yl）-2,5-diphenyl tetrazolium bromide and lactate dehydrogenase assays and nuclear morphological changes, DBDPE inhibited HepG2 viability in a time- and dose-dependent manner within a range of 12.5 mg/L to 100 mg/L and for 48 h and 72 h. Induction of apoptosis was detected at 12.5-100 mg/L at 48 h and 72 h by propidium iodide staining, accompanied with overproduction of reactive oxygen species （ROS）. Furthermore, N-acetyI-L-cysteine, a widely used ROS scavenger, significantly reduced DBDPE-induced ROS levels and increased HepG2 cells viability. Conclusion DBDPE has cytotoxic and anti-proliferation effect and can induce apoptosis in which ROS plays an important role
文摘Using forward and reverse genetics and global gene expression analyses, we explored the crosstalk between the IKB kinase β （IKKβ） and the transforming growth factor β （TGFβ） signaling pathways. We show that in vitro ablation of Ikkβ in fibroblasts led to progressive ROS accumulation and TGFβ activation, and ultimately accelerated cell migration, fibroblast-myofibroblast transformation and senescence. Mechanistically, the basal IKKβ activity was required for anti-oxidant gene expression and redox homeostasis. Lacking this activity, IKKβ-null cells showed ROS accumulation and activation of stress-sensitive transcription factor AP-1/c- Jun. AP-1/c-Jun activation led to up-regulation of the Tgfβ2 promoter, which in turn further potentiated intracellular ROS through the induction of NADPH oxidase （NOX）. These data suggest that by blocking the autocrine amplification of a ROS-TGFβ loop IKKβ plays a crucial role in the prevention of fibroblast-myofibroblast transformation and senescence.
文摘Cellular and mitochondrial damage can be caused by labile iron pool (LIP) and mediated by reactive oxygen species (ROS). Livers of the thalassemias have highly increased levels of LIP and ROS. Green tea extract (GTE) and epigallocatechin 3-gallatte (EGCG) can potentially protect liver inflammation, fibrosis and cancer due to their anti-oxidative and iron-chelating activities. We studied the effects of GTE and EGCG on intracellular LIP and ROS, and mitochondrial membrane potential (ΔΨm) in mouse hepatocyte and HepG2 cell cultures using specific fluorescent techniques. Treatment with GTE (12.5 - 25 mg/dl) and EGCG (25 - 50 μM) significantly lowered levels of ΔΨm in the mouse hepatocytes;however, combined treatment of 25 μM DFP with GTE and EGCG did not enhance the decrease of hepatic ΔΨm. The results showed that GTE and EGCG effectively removed the intracellular LIP and ROS, and relieved the mitochondria membrane collapse of the liver cells, suggesting a hepatoprotective effect of green tea extract and EGCG in the hepatocytes with iron overload. Their actions might be related to iron-chelating and free radical-scavenging capacities. Whether the effects can improve iron overload and oxidative stress in thalassemia patients remains to be seen upon further examination.
基金This work was supported by the National Natural Science Foundation of China （Grant No. 51136002） and the 12th Five- Year Key Program for Science and Technology Development of China （No. 2012BAJ02B0301）.
文摘Magnesium-aluminum layered double hydroxide （Mg/ALLDH） nanoparticles have strong potential application as drug delivery systems because of their low toxicity and suitable biocompatibility. However, few studies have described the morphological effects of these hydroxides on nerve cells. The present study compares the oxidative stress induced by different concentrations （i.e., 0, 50, 100, 200, 400, and 800 μg/mL） of sand flower and flake nano-Mg/ AI-LDHs in mouse neuroblastoma cells （N2a） when these cells were exposed for 24 and 48 h. Cell viability was detected by MTT assay, and production of reactive oxygen species （ROS）, glutathione （GSH）, and malondialdehyde （MDA） were monitored to evaluate oxidative damage. Results suggested that sand flower nano-LDHs, at the appropriate concentrations （less than 200 μg/mL）, especially those of about 100-200 nm in size, induce no harmful effects on N2a cells.
文摘The growth of seedlings of Townsville sytlo (Stylosanthes humilis H.B.K.) is inhibited by aluminium (Al) ions, their elongation being re-covered with sodium selenate at 1.0 μM. Methyl viologen and hydrogen peroxide, reactive oxy-gen species (ROS)-generating compounds, also inhibited seedling elongation and again growth was relieved by selenate. Selenate, thus, seemed to be operating as a ROS quencher, since N-acetylcysteine (NAC), an antioxidant com-pound, also stimulated largely the growth of Al-inhibited seedlings. At a higher concentra-tion (0.1 mM), however, selenate inhibited seed-ling growth and elongation was recovered by NAC. Ethylene production by selenate plus NAC-treated seedlings was very higher and thus the gaseous hormone was not responsible for the seedling growth inhibition caused by sele-nate. Hence, it seems that at high levels sele-nate operates as a ROS-generating compound whose effects were counteracted by NAC. It can be deduced that, at low concentration, sele-nates behave as a ROS quencher and at high level as a ROS-promoting species.
文摘Objective： This work aimed to study the inhibitory effect and the related mechanism of metformin （MET） on the proliferation of human hepatoma HepG2 cells. Methods： Human hepatoma HepG2 cells were treated with MET （0, 2, 10, and 50 mM）. The inhibitory effect of MET on the proliferation of HepG2 cells was determined by MTT method. The apoptosis of HepG2 cells was detected by flow cytornetry. The expression of cyclin D1 in HepG2 cells was examined by Western blot. ROS-DHE fluorescence probe was used to stain the reactive oxygen species （ROS） generated by HepG2 cells after treat- ment. Results： MET could inhibit the proliferation of HepG2 cells in a dose and time dependent manner. MET promoted the apoptosis of HepG2 cells. In addition, MET suppressed the expression of cell cycle protein cyclin D1 and induced the produc- tion of ROS in HepG2 cells. Conclusion： MET can inhibit the proliferation of human hepatoma HepG2 cells and induce cell apoptosis. Meanwhile, MET has the ability to decrease the expression of cyclin D1 and induce ROS generation, which may be involved in the mechanism of inhibiting hepatoma cells proliferation.
