内质网应激与动脉粥样硬化的研究进展

内质网应激是指细胞在缺血、氧化应激、钙稳态紊乱、蛋白质折叠错误或正常蛋白质表达增强等条件下发生的一系列适应性的保护反应。越来越多的研究表明,内质网应激在动脉粥样硬化发展的所有阶段均具有重要作用。该文主要综述了动脉管壁不同类型的细胞中内质网应激和细胞凋亡在动脉粥样硬化发展中的作用,并总结了目前调节这些途径的靶向分子以及它们在动脉粥样硬化治疗中的潜在疗效。     

核糖体相关质量控制与核糖体自噬研究进展

细胞中蛋白质处于不断合成和降解的动态更新过程中,其稳态与细胞功能密切相关。细胞中存在多种蛋白质质量控制（protein quality control,PQC）机制来监测蛋白质合成和降解过程的异常,以确保蛋白质组的完整性和细胞适应性。核糖体是细胞内数量最多的细胞器,系细胞内蛋白质合成的主要场所。现已明确,核糖体相关质量控制（ribosome-associated quality control,RQC）与核糖体自噬能通过溶酶体依赖和非依赖途径调节细胞内核糖体数量及功能以维持蛋白质稳态,从而增强细胞在应激状态下的适应能力。RQC失调、核糖体自噬障碍则参与多种疾病的发生及发展过程,靶向RQC和核糖体自噬可能成为防治多种疾病的有效手段。本综述聚焦核糖体相关的PQC途径,并进一步讨论了它们在蛋白质稳态维持中的重要地位及其在人类疾病发生发展中的潜在作用。     

血红素对人脐静脉内皮细胞氧化应激损伤的保护作用

采用过氧化氢作用于人脐静脉内皮细胞 ,成功地制作了氧化应激损伤的细胞模型 ,将培养的细胞分为 3组 :正常对照组 ,损伤组 (给予过氧化氢 )和血红素组 (同损伤组的制备 ,预先加入血红素 ) .观察各组细胞在光、电镜下形态学和蛋白质电泳的改变 ,用MTT法检测了各组细胞的生长状态 .结果表明 :在血红素组 ,细胞生长状态、MTT水平和蛋白质电泳结果与损伤组相比有明显好转且差异显著 ,证明血红素对人脐静脉内皮细胞氧化应激损伤有明显的保护作用 .     

免疫系统防御强，遇到缺氧HIF帮

缺氧诱导因子（hypoxia-inducible factor,HIF）是一类受氧调控的转录因子。其α亚基是氧敏感性亚基,包括HIF-1α、HIF-2α和HIF-3α,与β亚基形成异源二聚体,活化目标基因的表达以调节细胞对低氧的反应。HIF本身受到精细调节,包括转录组水平的调节,以及通过蛋白质翻译后修饰所进行的蛋白质水平的调节,以确保细胞对低氧压力产生适当反应。免疫应答常伴随局部组织的低氧状况,HIF是低氧环境中先天免疫和适应性免疫应答的重要调节因子。在天然免疫系统,HIF激活一系列与代谢相关的基因表达,调节中性粒细胞、巨噬细胞和树突状细胞的发育、极化和功能。对于适应性免疫,近年来的研究确立了HIF在CD4⁺T细胞分化和功能中的重要作用。本综述将重点讨论近年来有关HIF调节机制,及其在免疫细胞功能研究的进展。     

蛋白质的泛素化修饰在细胞应激反应中的作用

泛素是真核细胞内广泛存在的一种高度保守的蛋白质。在特定泛素化酶催化下实现的蛋白质泛素化修饰反应能够高选择性地降解细胞中的特定信号蛋白质,对维持细胞正常的生理功能具有非常重要的作用。另外,某些泛素化修饰反应也能够实现与蛋白质降解无关的功能调控作用。p53、NF-κB和GADD45α是在细胞应激损伤反应中具有广泛调控作用的信号蛋白,发生在这些分子上的泛素化修饰反应是它们发挥相关分子机制的重要基础。     

免疫系统防御强,遇到缺氧HIF帮（英文）

缺氧诱导因子(hypoxia-inducible factor,HIF)是一类受氧调控的转录因子。其α亚基是氧敏感性亚基,包括HIF-1α、HIF-2α和HIF-3α,与β亚基形成异源二聚体,活化目标基因的表达以调节细胞对低氧的反应。HIF本身受到精细调节,包括转录组水平的调节,以及通过蛋白质翻译后修饰所进行的蛋白质水平的调节,以确保细胞对低氧压力产生适当反应。免疫应答常伴随局部组织的低氧状况,HIF是低氧环境中先天免疫和适应性免疫应答的重要调节因子。在天然免疫系统,HIF激活一系列与代谢相关的基因表达,调节中性粒细胞、巨噬细胞和树突状细胞的发育、极化和功能。对于适应性免疫,近年来的研究确立了HIF在CD4+T细胞分化和功能中的重要作用。本综述将重点讨论近年来有关HIF调节机制,及其在免疫细胞功能研究的进展。     

乳酸菌源有机硒对肝损伤小鼠脾脏脂质过氧化和NK细胞活性的保护效应研究

本文通过研究乳酸菌源有机硒干预CCl_4致肝损伤小鼠脾脏NK细胞活性和脂质过氧化反应的变化,探讨该有机硒在抗损伤保护过程中的效应及其机制。分别选用60只健康成年小鼠,雌雄对半,随机分成对照组(C组),有机硒组(Se组),CCl_4组、CCl_4-有机硒保护组(CCl_4-Se组),每组15只。通过腹腔注射CCl_4诱发肝损伤后,分别在第2、4周检测脾脏NK细胞活性及其组织匀浆GSH-Px、CAT、SOD活性和MDA含量变化、结果显示,在整个实验期内,C组、Se组和CCl_4-Se组脾组织匀浆GSH—Px、CAT和SOD活性均高于或明显高于CCl_4组,Se和CCl_4-Se组与C组比较除SOD活性在第4周有明显升高外均差异不显著;CCl_4组小鼠脾脏MDA含量均显著高于C组、Se组和CCl_4-Se组,而CCl_4-Se组与C组接近,Se组较CCl_4-Se组和C组低;Se组NK细胞活性最高,第4周明显高于C组,CCl_4组最低且低于或明显低于CCl_4-Se、Se和C组,CCl_4-Se组与C组无明显差异。结果提示,乳酸菌源有机硒能够提高正常机体抗氧化能力,在干预肝损伤过程中,可以通过改善和提高脾组织抗氧化酶活性及NK细胞活性发挥积极有效的作用。     

乳酸菌酸胁迫反应机制研究进展

乳酸菌可发酵糖类产生乳酸,并广泛应用于食品、药物和饲料等工业。由于有机酸的积累,乳酸菌大部分的生长代谢都在低pH的酸性环境中进行,具有酸胁迫反应。pH的自我平衡、ATR反应机制、对大分子的保护和修复作用及细胞膜的变化等是乳酸菌酸胁迫反应的主要机制,其中,pH自我平衡包括F0F1-ATPase质子泵、精氨酸脱氨酶途径(ADI)和谷氨酸脱羧酶途径(GAD)等。由此可见,乳酸菌酸胁迫反应机制涉及到基因和蛋白的表达调控等,是非常复杂的网络调控体系。     

乳酸菌蛋白质分泌表达研究进展

食品级乳酸菌不仅是食品或消化道中传递异源蛋白质的合适的候选菌,在工业发酵中还可用于生产蛋白质。在过去20多年中,人们设计了许多乳酸菌蛋白质表达和标记系统,这些系统已用在乳酸菌工程菌的细胞内或细胞外生产各种细菌、病毒和真核生物来源的蛋白质。在目的蛋白生产和发酵中,分泌表达由于可持续培养和简化纯化步骤并使目的蛋白与其靶位相互作用而优于细胞质表达。目前只有少数研究报道了目的蛋白在乳酸菌细胞内或分泌表达产量的比较,研究表明分泌表达比细胞质表达更优越。     

猪源A组轮状病毒重组质粒pW425et-Vp7在乳酸菌中的表达及免疫原性分析

[目的]在乳酸菌中表达猪源A组轮状病毒重组质粒pW425et-Vp7,并检测其抗原性,为进一步制备猪轮状病毒乳酸菌疫苗奠定基础.[方法]摸索电转化条件,将已构建的重组质粒pW425et-Vp7转化至thyA基因缺陷型的嗜酸乳杆菌中.筛选阳性克隆,采用SDS-PAGE和Westernblot检测其表达情况.并将BALB/c小鼠口服免疫该重组菌,间接ELISA检测其免疫原性.另外,给免疫后小鼠攻以纯化的猪轮状病毒(蛋白含量15 mg/mL),初步检测该重组菌的免疫保护作用.[结果]Vp7基因在乳酸菌中获得表达,大小约40.77 kDa,且该蛋白可与猪轮状病毒抗体反应,具有反应原性.ELISA检测小鼠肠黏膜样品结果显示免疫后小鼠能产生明显的抗轮状病毒SIgA抗体,表明该重组菌具有较好的免疫原性.且攻毒后,免疫组仅23%的小鼠发生腹泻,初步证明该重组菌对猪轮状病毒的攻击具有较好的保护作用.[结论]在乳酸菌中成功地表达了猪轮状病毒Vp7基因,制备了猪轮状病毒Vp7重组乳酸菌,该重组菌具有较好的抗原性,初步证明其作为疫苗的可行性.     

Lactobacillus,Bifidobacterium and Lactococcus response to environmental stress: Mechanisms and application of cross-protection to improve resistance against freeze-drying

The review deals with lactic acid bacteria in characterizing the stress adaptation with cross-protection effects, mainly associated with Lactobacillus, Bifidobacterium and Lactococcus. It focuses on adaptation and cross-protection in Lactobacillus, Bifidobacterium and Lactococcus, including heat shocking, cold stress, acid stress, osmotic stress, starvation effect, etc. Web of Science, Google Scholar, Science Direct, and PubMed databases were used for the systematic search of literature up to the year 2020. The literature suggests that a lower survival rate during freeze-drying is linked to environmental stress. Protective pretreatment under various mild stresses can be applied to lactic acid bacteria which may enhance resistance in a strain-dependent manner. We investigate the mechanism of damage and adaptation under various stresses including heat, cold, acidic, osmotic, starvation, oxidative and bile stress. Adaptive mechanisms include synthesis of stress-induced proteins, adjusting the composition of cell membrane fatty acids, accumulating compatible substances, etc. Next, we reveal the cross-protective effect of specific stress on the other environmental stresses. Freeze-drying is discussed from three perspectives including the regulation of membrane, accumulation of compatible solutes and the production of chaperones and stress-responsive proteases. The resistance of lactic acid bacteria against technological stress can be enhanced via cross-protection, which improves industrial efficiency concerning the survival of probiotics. However, the adaptive responses and cross-protection are strain-dependent and should be optimized case by case.     

应用双向荧光差异凝胶技术解析干酪乳杆菌Lactobacillus casei Zhang驯化菌株耐酸胁迫机制

以干酪乳杆菌Lactobacillus casei Zhang为出发菌株,通过适应性进化获得了干酪乳杆菌酸胁迫抗性驯化菌株.对细胞内微环境的检测发现,驯化菌株在酸胁迫过程中能够维持较高的磷酸烯醇式丙酮酸-糖转移酶系统活力,并具有较高的H+ -ATPase活性以及胞内ATP浓度.蛋白质组学分析结果表明,酸胁迫引发了细胞蛋白表达的变化,与原始菌株相比,驯化菌株保持了更高的代谢活性;同时,驯化菌株通过大量诱导应激蛋白如分子伴侣GroEL、GrpE,冷/热应激蛋白CspC、DnaK等维持了细胞的生理活性,有效提高了细胞对酸胁迫的抵御能力.本研究为进一步揭示酸胁迫下乳酸菌细胞的生理应答机制,探寻促进乳酸菌酸胁迫性能提升的最优策略,进而改善其在生产中的应用性能提供了可借鉴的思路.     

Microbes versus microbes: immune signals generated by probiotic lactobacilli and their role in protection against microbial pathogens

Probiotic lactic acid bacteria can signal the immune system through innate cell surface pattern recognition receptors or via direct lymphoid cell activation. In some cases, this action has been shown to be sufficient to modulate local- and systemic-level in vivo immune responses. Practical applications of probiotics include their use in anti-tumour and anti-allergy immunotherapy, but there is also increasing evidence that some probiotics can stimulate a protective immune response sufficiently to enhance resistance to microbial pathogens. This review outlines the experimental and clinical evidence for enhanced anti-microbial immune protection by probiotic lactic acid bacteria, focussing on those studies where a correlative or suggestive link has been shown between immune modulation and enhanced protection.     

Lactococcus lactis and stress

It is now generally recognized that cell growth conditions in nature are often suboptimal compared to controlled conditions provided in the laboratory. Natural stresses like starvation and acidity are generated by cell growth itself. Other stresses like temperature or osmotic shock, or oxygen, are imposed by the environment. It is now clear that defense mechanisms to withstand different stresses must be present in all organisms. The exploration of stress responses in lactic acid bacteria has just begun. Several stress response genes have been revealed through homologies with known genes in other organisms. While stress response genes appear to be highly conserved, however, their regulation may not be. Thus, search of the regulation of stress response in lactic acid bacteria may reveal new regulatory circuits. The first part of this report addresses the available information on stress response in Lactococcus lactis.Acid stress response may be particularly important in lactic acid bacteria, whose growth and transition to stationary phase is accompanied by the production of lactic acid, which results in acidification of the media, arrest of cell multiplication, and possible cell death. The second part of this report will focus on progress made in acid stress response, particularly in L. lactis and on factors which may affect its regulation. Acid tolerance is presently under study in L. lactis. Our results with strain MG1363 show that it survives a lethal challenge at pH 4.0 if adapted briefly (5 to 15 minutes) at a pH between 4.5 and 6.5. Adaptation requires protein synthesis, indicating that acid conditions induce expression of newly synthesized genes. These results show that L. lactis possesses an inducible response to acid stress in exponential phase.To identify possible regulatory genes involved in acid stress response, we determined low pH conditions in which MG1363 is unable to grow, and selected at 37°C for transposition insertional mutants which were able to survive. About thirty mutants resistant to low pH conditions were characterized. The interrupted genes were identified by sequence homology with known genes. One insertion interrupts ahrC, the putative regulator of arginine metabolism; possibly, increased arginine catabolism in the mutant produces metabolites which increase the pH. Several other mutations putatively map at some step in the pathway of (p)ppGpp synthesis. Our results suggest that the stringent response pathway, which is involved in starvation and stationary phase survival, may also be implicated in acid pH tolerance.     

Priming and memory of stress responses in organisms lacking a nervous system

Experience and memory of environmental stimuli that indicate future stress can prepare (prime) organismic stress responses even in species lacking a nervous system. The process through which such organisms prepare their phenotype for an improved response to future stress has been termed ‘priming’. However, other terms are also used for this phenomenon, especially when considering priming in different types of organisms and when referring to different stressors. Here we propose a conceptual framework for priming of stress responses in bacteria, fungi and plants which allows comparison of priming with other terms, e.g. adaptation, acclimation, induction, acquired resistance and cross protection. We address spatial and temporal aspects of priming and highlight current knowledge about the mechanisms necessary for information storage which range from epigenetic marks to the accumulation of (dormant) signalling molecules. Furthermore, we outline possible patterns of primed stress responses. Finally, we link the ability of organisms to become primed for stress responses (their ‘primability’) with evolutionary ecology aspects and discuss which properties of an organism and its environment may favour the evolution of priming of stress responses.     

Study of intraspecific variations of the bacterium Lactococcus lactis in adaptation to high acidity of the medium

This paper reports on the study of acid tolerance of lactic acid bacteria as a property of cells, determining their ability to divide efficiently and retain viability under conditions of increased nutrient medium acidity during bacterial growth. The bacteria of the strain TV2, isolated from a self-soured curd, similar to the bacteria of the strain STE05 (Russian National Collection of Industrial Microorganisms), were assigned to the species Lactococcus lactis according to their G+C composition (36.7-36.5 mol %) and the high level of DNA-DNA hybridization (93%). However, these strains were essentially different in the number and size of the plasmids and the chromosomal DNA restriction fragments, as well as in the sensitivity to phages of lactic acid bacteria. It was found that bacteria of the strain TV2 were stable (i.e., they divided efficiently at a pH as low as 5.3) and tolerant to the lactic acid that they produced while growing (i.e., they retained viability at pH 4.4). Bacteria of the strain STE05 lacked acid tolerance (at pH below 6.5, growth was retarded, and pH 5.0 was the lowest value at which the cells remained viable). The acid tolerance and phage resistance of TV2 bacteria are likely to characterize their higher adaptive capacity in comparison with STE05 bacteria. Acid tolerance is inherited in a stable manner and retained by the segregants of TV2 strain obtained in the course of long-term storage of the bacteria. Specifically, the strains TV29, TV13, and TV 229, which displayed this property, had altered physiological and biochemical characteristics (accumulation of biomass and fermentation of lactose) in spite of their genetic identity to the original strain (pulsed-field gel electrophoresis of chromosomal DNA restriction fragments).     

乳酸菌渗透胁迫相关相容性溶质及其转运机制研究进展

渗透胁迫严重影响乳酸菌的生理功能, 制约着相关产品开发。近年来相容性溶质作为响应乳酸菌渗透胁迫的重要功能物质受到广泛关注。本文综述了国内外与乳酸菌响应渗透胁迫相关相容性物质的种类和特性, 在此基础上进一步介绍了其转运机制, 并对后续研究进行展望。