检测不同毒力结核分枝杆菌感染对巨噬细胞凋亡的影响及其Caspase-3和Bcl-2的表达

该文为探讨不同毒力的结核分枝杆菌感染对巨噬细胞凋亡的调控作用及其机制。实验用结核分枝杆菌国际标准强毒株H37Rv株和卡介苗BCG分别感染巨噬细胞RAW264.7株,同时设空白对照组,在感染后1,6,12,24 h,用流式细胞技术检测各组巨噬细胞的凋亡率,应用Western blot检测细胞Caspase-3和Bcl-2蛋白表达。结果发现,结核分枝杆菌感染组的凋亡率显著高于对照组,差异具有统计学意义(P<0.05);BCG感染组凋亡率高于H37Rv感染组,在感染后1,12,24 h凋亡率显著升高,差异具有统计学意义(P<0.05)。巨噬细胞感染结核分枝杆菌后其Caspase-3蛋白表达增高,结核分枝杆菌感染组的Caspase-3蛋白表达高于对照组:对照组相似文献   

An Oligopeptide Transporter Gene Family in Arabidopsis

We have identified nine oligopeptide transporter (OPT) orthologs (AtOPT1 to AtOPT9) in Arabidopsis. These proteins show significant sequence similarity to OPTs of Candida albicans (CaOpt1p), Schizosaccharomyces pombe (Isp4p), and Saccharomyces cerevisiae (Opt1p and Opt2p). Hydrophilicity plots of the OPTs suggest that they are integral membrane proteins with 12 to 14 transmembrane domains. Sequence comparisons showed that the AtOPTs form a distinct subfamily when compared with the fungal OPTs. Two highly conserved motifs (NPG and KIPPR) were found among all OPT members. The identification of multiple OPTs in Arabidopsis suggests that they may play different functional roles. This idea is supported by the fact that AtOPTs have a distinct, tissue-specific expression pattern. The cDNAs encoding seven of the AtOPTs were cloned into a yeast vector under the control of a constitutive promoter. AtOPT4 expressed in S. cerevisiae mediated the uptake of KLG-[3H]L. Similarly, expression of five of the seven AtOPT proteins expressed in yeast conferred the ability to uptake tetra- and pentapeptides as measured by growth. This study provides new evidence for multiple peptide transporter systems in Arabidopsis, suggesting an important physiological role for small peptides in plants.     

Modern Lineages of Mycobacterium tuberculosis Exhibit Lineage-Specific Patterns of Growth and Cytokine Induction in Human Monocyte-Derived Macrophages

Background

Strains of Mycobacterium tuberculosis vary in virulence. Strains that have caused outbreaks in the United States and United Kingdom have been shown to subvert the innate immune response as a potential immune evasion mechanism. There is, however, little information available as to whether these patterns of immune subversion are features of individual strains or characteristic of broad clonal lineages of M. tuberculosis.

Methods

Strains from two major modern lineages (lineage 2 [East-Asian] and lineage 4 [Euro-American]) circulating in the Western Cape in South Africa as well as a comparator modern lineage (lineage 3 [CAS/Delhi]) were identified. We assessed two virulence associated characteristics: mycobacterial growth (in liquid broth and monocyte derived macrophages) and early pro-inflammatory cytokine induction.

Results

In liquid culture, Lineage 4 strains grew more rapidly and reached higher plateau levels than other strains (lineage 4 vs. lineage 2 p = 0.0024; lineage 4 vs. lineage 3 p = 0.0005). Lineage 3 strains were characterized by low and early plateau levels, while lineage 2 strains showed an intermediate growth phenotype. In monocyte-derived macrophages, lineage 2 strains grew faster than lineage 3 strains (p<0.01) with lineage 4 strains having an intermediate phenotype. Lineage 2 strains induced the lowest levels of pro-inflammatory TNF and IL-12p40 as compared to other lineages (lineage 2: median TNF 362 pg/ml, IL-12p40 91 pg/ml; lineage 3: median TNF 1818 pg/ml, IL-12p40 123 pg/ml; lineage 4: median TNF 1207 pg/ml, IL-12p40 205 pg/ml;). In contrast, lineage 4 strains induced high levels of IL-12p40 and intermediate level of TNF. Lineage 3 strains induced high levels of TNF and intermediate levels of IL-12p40.

Conclusions

Strains of M. tuberculosis from the three major modern strain lineages possess distinct patterns of growth and cytokine induction. Rapid growth and immune subversion may be key characteristics to the success of these strains in different human populations.     

结核分枝杆菌与巨噬细胞相互作用的研究进展

结核分枝杆菌（Mycobacterium tuberculosis,MTB）是一种典型的胞内致病菌,巨噬细胞是MTB在体内的主要宿主细胞。巨噬细胞具有强大的吞噬功能,在机体固有免疫和适应性免疫中均发挥着重要作用,可有效保护宿主免受结核分枝杆菌的感染。MTB在与宿主巨噬细胞的长期相互作用过程中,逐渐形成多种逃避杀灭的有效策略,得以在宿主体内存活并增殖。该文从巨噬细胞抗MTB感染及MTB逃避巨噬细胞杀灭两个方面综述国内外的研究进展。     

Evolution of the Oligopeptide Transporter Family

The oligopeptide transporter (OPT) family of peptide and iron-siderophore transporters includes members from both prokaryotes and eukaryotes but with restricted distribution in the latter domain. Eukaryotic members were found only in fungi and plants with a single slime mold homologue clustering with the fungal proteins. All functionally characterized eukaryotic peptide transporters segregate from the known iron-siderophore transporters on a phylogenetic tree. Prokaryotic members are widespread, deriving from many different phyla. Although they belong only to the iron-siderophore subdivision, genome context analyses suggest that many of them are peptide transporters. OPT family proteins have 16 or occasionally 17 transmembrane-spanning α-helical segments (TMSs). We provide statistical evidence that the 16-TMS topology arose via three sequential duplication events followed by a gene-fusion event for proteins with a seventeenth TMS. The proposed pathway is as follows: 2 TMSs → 4 TMSs → 8 TMSs → 16 TMSs → 17 TMSs. The seventeenth C-terminal TMS, which probably arose just once, is found in just one phylogenetic group of these homologues. Analyses for orthology revealed that a few phylogenetic clusters consist exclusively of orthologues but most have undergone intermixing, suggestive of horizontal transfer. It appears that in this family horizontal gene transfer was frequent among prokaryotes, rare among eukaryotes and largely absent between prokaryotes and eukaryotes as well as between plants and fungi. These observations provide guides for future structural and functional analyses of OPT family members.     

Mannose Receptor 1 Restricts HIV Particle Release from Infected Macrophages

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The Balance of Apoptotic and Necrotic Cell Death in Mycobacterium tuberculosis Infected Macrophages Is Not Dependent on Bacterial Virulence

Background

An important mechanism of Mycobacterium tuberculosis pathogenesis is the ability to control cell death pathways in infected macrophages: apoptotic cell death is bactericidal, whereas necrotic cell death may facilitate bacterial dissemination and transmission.

Methods

We examine M.tuberculosis control of spontaneous and chemically induced macrophage cell death using automated confocal fluorescence microscopy, image analysis, flow cytometry, plate-reader based vitality assays, and M.tuberculosis strains including H37Rv, and isogenic virulent and avirulent strains of the Beijing lineage isolate GC1237.

Results

We show that bacterial virulence influences the dynamics of caspase activation and the total level of cytotoxicity. We show that the powerful ability of M.tuberculosis to inhibit exogenously stimulated apoptosis is abrogated by loss of virulence. However, loss of virulence did not influence the balance of macrophage apoptosis and necrosis – both virulent and avirulent isogenic strains of GC1237 induced predominantly necrotic cell death compared to H37Rv which induced a higher relative level of apoptosis.

Conclusions

This reveals that macrophage necrosis and apoptosis are independently regulated during M. tuberculosis infection of macrophages. Virulence affects the level of host cell death and ability to inhibit apoptosis but other strain-specific characteristics influence the ultimate mode of host cell death and alter the balance of apoptosis and necrosis.     

细胞因子和microRNA与结核分枝杆菌感染的研究进展

细胞因子是由免疫细胞和某些非免疫细胞经刺激而合成、分泌的一类具有广泛生物学活性的小分子蛋白质,其作为细胞间信号传递分子,主要参与调节免疫应答、免疫细胞分化发育、组织修复、介导炎症反应、刺激造血功能等。micro RNA(mi RNA)是存在于真核细胞内的一种非编码小RNA,可以调控基因转录后的表达,同时还可作为不同生理和病理状态的分子标记。许多研究表明,细胞因子相关基因的多态性与结核感染、肺结核发病易感性密切相关,而mi RNA在肺部疾病的正负调节功能与肺部疾病感染的发生、发展、转化与治疗有关。我们简要叙述了细胞因子、mi RNA与结核分枝杆菌感染三者之间的关联,以期有利于及时筛查潜伏结核感染和肺结核患者,降低结核感染率和发病率。     

巨噬细胞凋亡对结核分枝杆菌感染的机制研究进展

结核病是一种严重危害人类健康的慢性传染性疾病,主要由结核分枝杆菌感染导致,结核分枝杆菌进入人体后,与免疫防御的第一道屏障—巨噬细胞发生反应,部分菌株在细胞内长期生存、繁殖,是导致结核病转归的决定性因素。感染早期,结核分枝杆菌的繁殖受到巨噬细胞凋亡的抑制,随着高效价、高毒力菌株繁殖速度的增加,抗巨噬细胞凋亡作用不断增强,使自身繁殖得到有效保护,为菌株的生长提供了充足、适宜的胞内环境。因此,调控结核分枝杆菌对巨噬细胞凋亡进程的抑制作用,是预防和治疗结核病的关键。     

The Cellular Prion Protein Negatively Regulates Phagocytosis and Cytokine Expression in Murine Bone Marrow-Derived Macrophages

The cellular prion protein (PrP^C) is a glycosylphosphatidylinositol (GPI)-anchored glycoprotein on the cell surface. Previous studies have demonstrated contradictory roles for PrP^C in connection with the phagocytic ability of macrophages. In the present work, we investigated the function of PrP^C in phagocytosis and cytokine expression in bone marrow-derived macrophages infected with Escherichia coli. E. coli infection induced an increase in the PRNP mRNA level. Knockout of PrP^C promoted bacterial uptake; upregulated Rab5, Rab7, and Eea1 mRNA expression; and increased the recruitment of lysosomal-associated membrane protein-2 to phagosomes, suggesting enhanced microbicidal activity. Remarkably, knockout of PrP^C suppressed the proliferation of internalized bacteria and increased the expression of cytokines such as interleukin-1β. Collectively, our data reveal an important role of PrP^C as a negative regulator for phagocytosis, phagosome maturation, cytokine expression, and macrophage microbicidal activity.     

乙酰化修饰调控结核杆菌异柠檬酸裂合酶的研究

目的:探索结核杆菌异柠檬酸裂合酶(ICL)蛋白322位点赖氨酸(Lys322)的乙酰化修饰对蛋白功能的调控作用。方法:构建结核杆菌ICL蛋白原核表达载体p ET28a-icl,并对Lys322位点进行定点突变为精氨酸(Arg,R)和谷氨酰胺(Glu,Q),体外表达纯化获得重组蛋白ICLWT、ICL322R和ICL322Q。通过Western blotting和酶活性测定来揭示Lys322位点突变前后对蛋白的乙酰化修饰水平及蛋白功能的影响。结果:Western blotting检测发现大肠杆菌表达体系获得的ICLWT、ICL322R和ICL322Q蛋白均有较高水平的蛋白赖氨酸乙酰化修饰信号,较ICLWT,ICL322R和ICL322Q突变蛋白的酶活性分别下降了大约50%和70%。结论:在大肠杆菌的表达体系中,ICL蛋白可以获得乙酰化修饰。ICL322Q突变蛋白酶活性的显著下降,揭示Lys322位点乙酰化修饰对ICL蛋白的功能存在负向调控。为未来深入探索赖氨酸乙酰化修饰对结核杆菌代谢,潜伏感染的调控作用奠定了基础。     

寡肽转运蛋白PepT2及其药物转运

PepT2（peptide transporter 2）是一种高亲和力、低容量的转运载体.它在人体中分布广泛,不仅能转运二、三肽,也可以识别和转运许多仿肽类药物,如β-内酰胺抗生素、血管紧张素转换酶抑制剂、贝他定等.研究表明,PepT2的转运机制不同于氨基酸的吸收机制,其底物的仿肽结构特征影响其转运速率. 本文综述了PepT2与药物相互作用的研究以及PepT2转运药物底物结构特征的研究进展.