益生菌联合白藜芦醇对小鼠慢性酒精性肝损伤的改善作用及机制研究

利用C57BL/6J小鼠构建慢性酒精性肝损伤模型,探究益生菌联合白藜芦醇对慢性酒精性肝损伤的保护作用及可能机制。小鼠被随机分为空白对照组（Con组)和酒精模型组(Mod组）,三组益生菌分别联合白藜芦醇（Resveratrol,Res）干预组（Lactobacillus paracasei J5+Res（J5+Res）、Lactobacillus casei YRL577+Res（YRL577+Res）、Bifidobacterium animalis F1-7+Res（F1-7+Res））和阳性药物硫普罗宁组（LP组）。实验结束后,通过分析小鼠肝脏脂质含量、酒精代谢酶活性、氧化应激水平等指标,对益生菌联合白藜芦醇的作用效果进行评价。为了进一步探究联合作用机制,对肝脏中氧化应激相关基因CYP2E1、核因子 E2 相关因子 2（Nuclear factor erythroid-2-related factor 2, Nrf2）、血红素加氧酶1（Heme oxygenase-1,HO-1）的mRNA表达进行分析。结果表明,相较于Mod组,益生菌联合白藜芦醇能够显著降低小鼠肝脏中甘油三脂、总胆固醇含量、血清谷草转氨酶和谷丙转氨酶活力（P<0.05）,提高肝脏乙醇脱氢酶、乙醛脱氢酶活性并抑制肝脏CYP2E1活性及其mRNA表达,显著提高肝脏还原型谷胱甘肽含量和超氧化物歧化酶、过氧化氢酶活性（P<0.05）,并能有效激活Nrf2/HO-1通路,其中,Nrf2 mRNA表达量在J5+Res、YRL577+Res、F1-7+Res三组益生菌联合干预组中分别被上调了2.6、3.7和2.7倍,HO-1 mRNA表达量被上调了2.0、6.2和4.0倍。因此,益生菌联合白藜芦醇可能通过激活Nrf2/HO-1途径预防慢性酒精性肝损伤。     

白藜芦醇对不同时间高糖诱导HepG2细胞氧化损伤的保护作用

研究白藜芦醇对不同时间高糖诱导HepG2氧化损伤的保护作用。33 mmol/L高糖作为诱导剂,与不同浓度白藜芦醇(0.1、1、10μmol/L)共同孵育24、48、72 h,采用MTT法检测其对损伤细胞存活率的影响,DCFH-DA荧光探针法检测细胞自由基水平,测定细胞超氧化物歧化酶(SOD)、丙二醛(MDA)、谷胱甘肽过氧化物酶(GSH-PX)、总抗氧化能力(T-AOC)水平,Real-time PCR测定Nrf2、HO-1 mRNA表达水平,探讨白藜芦醇对高糖损伤细胞的保护作用及可能机制。结果表明,白藜芦醇与高糖共同作用48 h以上时,各浓度组均能显著提高损伤细胞存活率,显著降低细胞自由基水平(p0.05);各浓度组均能改善模型氧化还原状态,其中10μmol/L白藜芦醇作用48 h时效果极显著(p0.01);10μmol/L白藜芦醇作用48 h时,极显著上调Nrf2、HO-1mRNA表达水平(p0.01)。因此,白藜芦醇能通过清除细胞自由基、改善细胞氧化还原状态、上调抗氧化通路相关基因表达,抑制高糖诱导HepG2细胞的损伤。     

白藜芦醇对晚期糖基化终末产物诱导INS-1细胞损伤的保护作用及机制

目的:研究白藜芦醇(RSV)对晚期糖基化终末产物(AGEs)诱导大鼠胰岛素瘤细胞(INS-1)损伤的保护作用及其抗炎抗氧化应激机制。方法:本实验使用含AGEs的糖化血清(GS)建立INS-1细胞损伤模型。实验分对照组、20% GS模型组、20% GS+不同浓度RSV组。检测各组细胞增殖率、细胞内超氧化物歧化酶(SOD)活性、还原型谷胱甘肽(GSH)含量、培养液上清一氧化氮(NO)和细胞内活性氧(ROS)、丙二醛(MDA)含量以及培养液上清肿瘤坏死因子(TNF-α)含量。结果:与对照组比较,模型组INS-1细胞增殖率、SOD活性和GSH的含量极显著降低(p<0.01),NO和ROS含量极显著升高(p<0.01),MDA含量显著升高(p<0.05),TNF-α含量极显著降低(p<0.01)。与模型组比较,25和50 μmol/L的RSV组INS-1细胞增殖率均极显著提高(p<0.01),同时SOD活力和GSH含量极显著升高(p<0.01),NO的水平极显著降低(p<0.01)。此外,50 μmol/L的RSV组ROS含量显著降低(p<0.05),25 μmol/L的RSV组MDA含量显著降低(p<0.05),25和50 μmol/L的RSV组的TNF-α水平极显著降低(p<0.01)。结论:RSV对AGEs损伤的INS-1细胞有显著的保护作用,其作用机制可能是通过提高INS-1细胞的抗氧化应激能力和抗炎症反应能力实现的。     

Assembly interdependence among the S. cerevisiae bud neck ring proteins Elm1p,Hsl1p and Cdc12p

In Saccharomyces cerevisiae, a complex comprising more than 20 different polypeptides assembles in a ring at the neck between the mother cell and the bud. This complex functions to coordinate cell morphology with cell division. Relatively little is known about this control system, including the physical relationships between the components of the neck ring. This study addressed the assembly interactions of three components of the ring, specifically the protein kinases Elm1p and Hsl1p and the septin Cdc12p. Specific amino acid substitutions in each of these three proteins were identified that either cause or suppress a characteristic phenotype of abnormally elongated cells and delay in the G(2)-M transition. Each protein was fused to green fluorescent protein, and its ability to localize at the neck was monitored in vivo in cells of various genotypes. Localization of Hsl1p to the neck requires Elm1p function. Elm1p localized normally in the absence of Hsl1p, although a specific point mutation in Hsl1p clearly affected Elm1p localization. The cdc12-122 mutation prevented assembly of Elm1p or Hsl1p into the neck ring. Normal assembly of Cdc12p at the neck was dependent upon Elm1p and also, to a smaller extent, on Hsl1p. Ectopic localization of Cdc12p at the bud tip was observed frequently in elm1 mutants and also, to a lesser extent, in hsl1 mutants. Thus, Elm1p is a key factor in the assembly and/or maintenance of Hsl1p, as well as at least one septin, into the bud neck ring.     

Resveratrol Preserves Mitochondrial Function,Stimulates Mitochondrial Biogenesis,and Attenuates Oxidative Stress in Regulatory T Cells of Mice Fed a High‐Fat Diet

Consumption of high‐fat diet (HFD) is related with increased oxidative stress and dysfunctional mitochondria in many organs. The effects of resveratrol (trans‐3,5,4′‐trihydroxystilbene) that can protect T lymphocytes in various disease conditions on the HFD‐induced apoptosis of CD4⁺CD25⁺CD127^low/? regulatory T cells (Tregs) were studied, and the possible mechanism was postulated. Resveratrol significantly decreased Tregs death induced by 20‐wk HFD, being associated with the reduction of reactive oxygen species production and the alleviation of HFD‐induced loss of mitochondrial membrane potential (Δψm) in Tregs. Furthermore, resveratrol increased the expression of factors that regulated mitochondrial biogenesis in Tregs. Finally, resveratrol recovered the HFD‐induced activation of apoptotic markers in Tregs. Resveratrol protected Tregs against HFD‐induced apoptosis by reducing oxidative stress, restoring mitochondrial functional activities, and stimulating mitochondrial biogenesis.     

Role of Tea1p, Tea3p and Pom1p in the determination of cell ends in Schizosaccharomyces pombe

Schizosaccharomyces pombe cells are rod-shaped and grow along a single axis from their two ends. Microtubules extend from the cell centre terminating at the cell ends. The ERM(ezrin/radixin/moesin)-like proteins Tea1p and Tea3p, and the Dyrk-like kinase Pom1p are cell end markers involved in the regulation of growth and microtubular dynamics at the cell ends. We have analysed the relative contribution of these three proteins to the determination of cell ends as sites both for cell growth and for microtubular termination. Pom1Delta, in combination with Tea1Delta or Tea3Delta, has the greatest difficulty in relocalizing actin to the cell ends following actin depolymerization and generates the most defective growth pattern. Tea1Delta, in combination with Pom1Delta or Tea3Delta, displays the highest number of microtubules bending round the cell ends. Tea1DeltaPom1Delta, which has the most defective growth pattern and microtubules, also displays the highest number of branched cells. We show that Tea1p, Tea3p and Pom1p all contribute, to different extents, to the determination of cell ends, as sites for both cell growth and microtubular termination. We also show that the fission yeast cell relies on both the positioning of landmarks and a properly organized microtubule cytoskeleton to direct cell growth.     

Methionine supply alters mammary gland antioxidant gene networks via phosphorylation of nuclear factor erythroid 2-like 2 (NFE2L2) protein in dairy cows during the periparturient period

The periparturient period is the most critical period during the lactation cycle of dairy cows and is characterized by increased oxidative stress status. The objective of this experiment was to evaluate the effect of supplementing rumen-protected methionine on nuclear factor erythroid 2-like 2 (NFE2L2, formerly NRF2) protein and target gene expression in the mammary gland during the early postpartal period. Multiparous Holstein cows were used in a block design experiment with 30 cows per treatment. Treatments consisting of a basal control diet (control) or the basal diet plus rumen-protected methionine (methionine) were fed from d ?28 to 60 relative to parturition. Mammary tissue biopsies were harvested on d 21 postpartum from 5 cows per treatment. Compared with control, methionine increased dry matter intake, milk yield, and milk protein content. Among plasma parameters measured, methionine led to greater methionine and lower reactive oxygen metabolites. Compared with control, methionine supply resulted in greater mRNA abundance of the NFE2L2 target genes glutamate-cysteine ligase catalytic subunit (GCLC), glutamate-cysteine ligase modifier subunit (GCLM), glutathione reductase (GSR), glutathione peroxidase 1 (GPX1), malic enzyme 1 (ME1), ferrochelatase (FECH), ferritin heavy chain 1 (FTH1), and NAD(P) H quinone dehydrogenase 1 (NQO1) in the mammary tissue. In addition, methionine upregulated the mRNA abundance of NFE2L2, NFKB1, MAPK14 and downregulated KEAP1. The ratio of phosphorylated NFE2L2 to total NFE2L2 protein, and total heme oxygenase 1 (HMOX1) protein were markedly greater in response to methionine supply. In contrast, total protein abundance of Kelch-like ECH-associated protein 1 (KEAP1), which sequesters NFE2L2 in the cytosol and reduces its activity, was lower with methionine. Besides the consistent positive effect of methionine supply on systemic inflammation and oxidative stress status, the present data indicate a positive effect also on antioxidant mechanisms within the mammary gland, which are regulated, at least in part, via phosphorylation of NFE2L2 and its target genes. The exact mechanisms for these responses merit further study.     

白藜芦醇通过降低LYRM1 mRNA表达抑制3T3-L1前脂肪细胞增殖

目的：观察白藜芦醇（resveratrol,Res）对3T3-L1前脂肪细胞增殖活性的影响,并探讨其机制。方法：对3T3-L1前脂肪细胞进行培养,分别设置对照组以及25、50、75、100 μmol/L的Res干预组,噻唑蓝比色法观察不同剂量干预对细胞增殖活性的影响;实时荧光定量聚合酶链反应检测细胞中LYR Motif containing 1（LYRM1）基因mRNA的表达情况;Western blotting实验检测细胞中促凋亡蛋白Bak和抑凋亡蛋白Bcl-2的表达水平。结果：Res干预可使3T3-L1前脂肪细胞增殖活性降低;细胞中LYRM1 mRNA水平降低,Bak蛋白表达含量升高,Bcl-2蛋白表达含量降低,均具有剂量依赖效应。结论：Res可以抑制3T3-L1前脂肪细胞增殖,这可能与Res降低细胞内LYRM1 mRNA表达,影响线粒体功能并启动凋亡程序有关。     

真菌中氧胁迫调控因子AP-1研究进展

氧化应激是细胞应激反应的一种,在所有生物中都是保守进化的。应激反应的调控包括转录、翻译和翻译后修饰,决定生物体是否适应、存活、或者死亡。酵母中b-ZIP型激活蛋白(Yap)家族包括8个成员,Yap1是酵母Yap家族中首先发现的成员,具有DNA结合结构域和转录激活活性,在细胞的氧化应激中发挥着必不可少的作用。在氧化压力下,Yap1的活性增加。本文对近年来AP-1转录因子在真菌中的主要研究进展进行了综述,重点介绍了AP-1作为主要的氧化应激调节器参与的生物学应激反应、致病性及产生真菌毒素等,并介绍了AP-1在铁代谢、钴毒性、DNA损伤、耐药性中的功能。     

The centromere-binding factor Cbf1p from Candida albicans complements the methionine auxotrophic phenotype of Saccharomyces cerevisiae

A gene encoding the centromere binding factor 1 (Cbf1p) of the human pathogenic yeast Candida albicans was cloned and characterized. An open reading-frame was detected which encoded a 223 amino acid protein with a calculated molecular weight of 25.8 kDa and a relative isoelectric point of 5.55. It shares 39% overall amino acid sequence identity with Saccharomyces cerevisiae Cbf1p. We localized the CaCBF1 gene on chromosome 4. Southern analysis indicated that CaCBF1 is probably present as a single copy gene per haploid genome. The CaCBF1 gene under the control of its own promoter was able to complement the methionine auxotrophic growth, the increased mitotic instability of CEN plasmids and the slow growth of a Saccharomyces cerevisiae cbf1Delta mutant strain.     

Nuclear factor erythroid 2-related factor 2 antioxidant response element pathways protect bovine mammary epithelial cells against H2O2-induced oxidative damage in vitro

The experiment was conducted to determine the role of nuclear factor (erythroid-derived 2)-like factor 2 (NFE2L2, formerly Nrf2) antioxidant response element (ARE) pathway in protecting bovine mammary epithelial cells (BMEC) against H₂O₂-induced oxidative stress injury. An NFE2L2 small interfering RNA (siRNA) interference or a pCMV6-XL5-NFE2L2 plasmid fragment was transfected to independently downregulate or upregulate expression of NFE2L2. Isolated BMEC in triplicate were exposed to H₂O₂ (600 μM) for 6 h to induce oxidative stress before transient transfection with scrambled siRNA, NFE2L2-siRNA, pCMV6-XL5, and pCMV6-XL5-NFE2L2. Cell proliferation, apoptosis and necrosis rates, antioxidant enzyme activities, reactive oxygen species (ROS) and malondialdehyde (MDA) production, protein and mRNA expression of NFE2L2 and downstream target genes, and fluorescence activity of ARE were measured. The results revealed that compared with the control, BMEC transfected with NFE2L2-siRNA3 had proliferation rates that were 9 or 65% lower without or with H₂O₂, respectively. These cells also had apoptosis and necrosis rates that were 27 and 3.5 times greater with H₂O₂ compared with the control group, respectively. In contrast, transfected pCMV6-XL5-NFE2L2 had proliferation rates that were 64.3% greater or 17% lower without or with H₂O₂ compared with the control group, respectively. Apoptosis rates were 1.8 times lower with H₂O₂ compared with the control. In addition, compared with the control, production of ROS and MDA and activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase (CAT), and glutathione-S-transferase (GST) increased markedly in cells transfected with pCMV6-XL5-NFE2L2 and without H₂O₂. However, compared with the control, production of ROS and MDA and activity of CAT and GSH-Px increased markedly, whereas activities of SOD and GST decreased in cells transfected with pCMV6-XL5-NFE2L2 and incubated with H₂O₂. Compared with the control, cells transfected with NFE2L2-siRNA3 with or without H₂O₂ had lower production of ROS and MDA and activity of SOD, CAT, GSH-Px, and GST. Cells transfected with pCMV6-XL5-NFE2L2 with or without H₂O₂ had markedly higher protein and mRNA expression of NFE2L2, heme oxygenase-1 (HMOX-1), NADH quinone oxidoreductase 1, glutamate cysteine ligase catalytic subunit, and glutamyl cystine ligase modulatory subunit compared with the control incubations. Cells transfected with NFE2L2-siRNA3 without or with H₂O₂ had markedly lower protein and mRNA expression of NFE2L2, HMOX-1, NADH quinone oxidoreductase 1, glutamyl cystine ligase modulatory subunit, and glutamate-cysteine ligase catalytic subunit compared with the control incubations. In addition, expression of HMOX-1 was 5.3-fold greater with H₂O₂ compared with the control. Overall, results indicate that NFE2L2 plays an important role in the NFE2L2-ARE pathway via the control of HMOX-1. The relevant mechanisms in vivo merit further study.     

Proteolytic processing of certain CaaX motifs can occur in the absence of the Rce1p and Ste24p CaaX proteases

The CaaX motif directs C‐terminal protein modifications that include isoprenylation, proteolysis and carboxylmethylation. Proteolysis is generally believed to require either Rce1p or Ste24p. While investigating the substrate specificity of these proteases, using the yeast a‐factor mating pheromone as a reporter, we observed Rce1p‐ and Ste24p‐independent mating (RSM) when the CKQQ CaaX motif was used in lieu of the natural a‐factor CVIA motif. Uncharged or negatively charged amino acid substitutions at the a₁ position of the CKQQ motif prevented RSM. Alanine substitutions at the a₂ and X positions enhanced RSM. Random mutagenesis of the CaaX motif provided evidence that RSM occurs with approximately 1% of all possible CaaX motif permutations. Combined mutational and genetic data indicate that RSM‐promoting motifs have a positively charged amino acid at the a₁ position. Two of nine naturally occurring yeast CaaX motifs conforming to this pattern promoted RSM. The activity of the isoprenylcysteine carboxyl methyltransferase Ste14p was required for RSM, indicating that RSM‐promoting CaaX motifs are indeed proteolysed. RSM was enhanced by the overexpression of Axl1p or Ste23p, suggesting a role for these M16A subfamily metalloproteases in this process. We have also determined that an N‐terminal extension of the a‐factor precursor, which is typically removed by the yeast M16A enzymes, is required for optimal RSM. These observations suggest a model that involves targeting of the a‐factor precursor to the peptidosome cavity of M16A enzymes where subsequent interactions between RSM‐promoting CaaX motifs and the active site of the M16A enzyme lead to proteolytic cleavage. Copyright © 2009 John Wiley & Sons, Ltd.