SapM诱导的自噬体-溶酶体融合阻断依赖于SapM和Rab7的相互作用

目的研究Rab7在结核分枝杆菌毒力因子分泌性酸性磷酸酶(SapM)诱导的自噬体-溶酶体融合阻断中的作用。方法采用Rab7小干扰RNA(si Rab7)转染Raw264.7细胞,Western blot法检测P62蛋白水平。m Cherry-SapM转染Raw264.7细胞后免疫荧光检测SapM与Rab7共定位情况,免疫共沉淀分析SapM与Rab7的关系。用3种SapM的突变体SapM△ARCA,SapM△FRED和SapM△CT转染Raw264.7细胞,分析SapM的不同突变体与Rab7的关系。结果 si Rab7处理后,细胞P62水平显著增高;免疫组织化学染色结果显示SapM与Rab7在胞内共定位;免疫共沉淀分析显示SapM与Rab7可相互沉淀;3种不同突变形式的SapM中,只有SapM△CT不能与Rab7相互作用。结论 SapM诱导的自噬体-溶酶体融合阻断依赖于SapM与Rab7的相互作用。     

RNA干扰对宫颈癌细胞中E6AP基因的影响及其意义

目的 探讨RNA干扰(RNAi)对宫颈癌细胞系HeLa细胞E6AP基因表达及细胞增殖和凋亡的影响.方法 实验分为3组:空白对照组(未经转染的HeLa细胞)、转染阴性对照的小干扰RNA(siRNA)组及转染特异性E6AP siRNA组.采用半定量RT-PCR技术、Western blot方法 检测E6AP mRNA、蛋白表达水平,用四甲基偶氮唑蓝比色(MTT)法检测细胞增殖状况,用流式细胞术检测细胞凋亡.结果 转染E6AP siRNA 24、48、72 h后,E6AP siRNA组E6AP mRNA表达水平与对照siRNA组比较下降33%、72%、70%.Western blot结果 显示,在转染48及72 h,E6AP蛋白表达下降38%、59%.MTT法检测显示,转染HeLa细胞24、48、72、96 h后细胞生长速度明显降低,E6AP siRNA组与空白对照组(F=101.38,P＜0.05)、对照siRNA组(F=38.64,P＜0.05)比较,差异均有统计学意义.E6AP siRNA作用24、48、72 h后E6AP siRNA组凋亡率明显高于对照siRNA组(F=41.48,P＜0.05)和空白对照组(F=86.36,P＜0.05),差异有统计学意义.结论 体外合成的siRNA能有效封闭宫颈癌细胞中E6AP基因的表达,抑制细胞增殖,促进细胞的凋亡,为宫颈癌的基因治疗提供理论依据.     

利用CRISPR / Cas9 技术构建Fbxw7 敲低的Raw264-7 稳定细胞株及其生理功能检测

目的:应用CRISPR/Cas9技术构建Fbxw7表达抑制的Raw264.7稳定巨噬细胞株,并检测其生理功能。方法:转染Fbxw7_Cas9KO质粒到Raw264.7细胞,用含嘌呤霉素的培养基培养,挑取单克隆并筛选带荧光标记的细胞进一步培养;然后采用qRT-PCR和Western blot分别检测Fbxw7基因与蛋白表达水平;Confocal进一步检测Fbxw7蛋白表达分布;测序分析基因突变情况;CCK-8和流式细胞术分别检测Fbxw7基因敲低后Raw264.7细胞增殖能力与凋亡率。结果:Fbxw7敲低组的mRNA和蛋白表达水平较正常Raw264.7细胞显著降低,Confocal观察发现敲低组Raw264.7细胞中Fbxw7蛋白表达微弱;测序结果显示Fbxw7敲低组存在多位点突变;Fbxw7敲低后Raw264.7细胞增殖能力明显降低,凋亡率增加。结论:利用CRISPR/Cas9技术可以实现Fbxw7基因在Raw264.7细胞稳定低表达,所筛选出的稳定细胞株可用于后续细胞水平的实验研究。     

P38 MAPK激活在高血糖致大鼠微血管通透性增高过程中的作用

目的研究P38 MAPK信号传导通路在糖尿病大鼠微血管内皮细胞通透性增高中的作用机制。方法SD雄性大鼠,腹腔注射链脲佐菌素(STZ 55 mg/kg)制备糖尿病模型。分正常组、糖尿病组、溶剂对照组、MKK6b(A)组和MKK6b(E)组。溶剂组:给予相同容量的柠檬酸缓冲液;MKK6b(A)组:在糖尿病模型基础上,实验前24 h尾静脉注射MKK6b(A)2.5 mL/kg;MKK6b(E)组:在实验前24 h给正常大鼠尾静脉注射MKK6b(E)2.5 mL/kg。用荧光强度检测微血管通透性;用荧光染色法观察微血管内皮细胞骨架蛋白的形态。结果糖尿病大鼠的微血管通透性明显高于正常组;注射MKK6b(E)可以增高大鼠微血管的通透性,而注射MKK6b(A)后微静脉的高通透性则被抑制。结论P38 MAPK信号转导系统参与介导了糖尿病微血管通透性增高的反应过程。     

JNK的激活在MPP诱导SHSY5Y细胞凋亡的信号转导中的作用

目的:探讨MPP⁺诱导SHSY5Y细胞凋亡的可能信号转导途径。方法:用吖啶橙-溴化乙锭染色观察SHSY5Y细胞凋亡率,Westernblot法检测JNK激酶的活性,用JNK反义寡核苷酸转染SHSY5Y细胞抑制JNK激酶的活性。结果:MPP⁺可诱导SHSY5Y细胞凋亡,在凋亡过程中JNK激酶活性增强,用NAC预处理或用JNK反义寡核苷酸转染后MPP⁺诱导的SHSY5Y细胞凋亡减少,同时JNK激酶活性增强可被抑制,裂解的caspase3阳性细胞数减少。结论:MPP⁺诱导SHSY5Y细胞凋亡,其可能的信号转导途径是通过JNK激酶的激活从而激活caspase3。     

脂多糖通过介导MFN1泛素化调控小鼠Raw264.7巨噬细胞线粒体稳态失衡和焦亡

目的探讨线粒体融合蛋白1(mitofusin 1, MFN1)对脂多糖(lipopolysaccharide, LPS)诱导的小鼠Raw264.7巨噬细胞焦亡的调控作用, 为预防巨噬细胞功能障碍导致的炎症和纤维化提供新的研究靶点和理论参考。方法体外培养小鼠单核巨噬细胞Raw264.7, 构建LPS诱导的细胞焦亡模型。CCK-8、PI染色、LDH释放、Western blot等验证LPS诱导Raw264.7细胞发生焦亡;Western blot筛选异常表达的线粒体相关蛋白MFN1;DCFH-DA探针检测细胞总活性氧生成情况、Mito-SOX探针检测线粒体活性氧水平、JC-1线粒体膜电位荧光探针检测线粒体膜电位变化以反映线粒体受损情况;利用Ubibrowser数据库预测出MFN1蛋白可与多种E3泛素连接酶结合, 通过免疫荧光、免疫共沉淀(co-immunoprecipitation, CO-IP)试验等验证MFN1蛋白是否受泛素化调控;采用Lipofectamine2000试剂转染MFN1过表达质粒检测MFN1蛋白对细胞焦亡和线粒体功能的影响。结果 LPS诱导Raw264.7细胞发生线粒体...     

α-硫辛酸降低脂多糖诱导的Raw264.7细胞TNF-α的分泌

目的观察α-硫辛酸(ALA)对脂多糖(LPS)在体外诱导的Raw264.7细胞TNF-α释放及机制。方法用ALA或者ALA联合ERK或NF-κB的抑制剂或者激活剂预处理2 h,再用LPS(1 mg/L)体外刺激巨噬细胞Raw264.7;采用MTT法检测ALA对Raw264.7细胞活力影响,利用ELISA方法对Raw264.7释放在培养上清中的细胞因子肿瘤坏死因子(TNF-α)的浓度,及用Western blot方法检测T-p ERK、p ERK和NF-κB的表达。结果 ALA可抑制LPS诱导的Raw264.7细胞TNF-α表达(P0.05),用ALA联合ERK或NF-κB的激活剂预处理后可减弱ALA产生的抑制效果(P0.05)。同时ALA抑制LPS诱导的Raw264.7细胞p ERK和NF-κB的表达(P0.05),用ALA联合ERK或NF-κB的抑制剂预处理后可加强ALA产生的抑制效果(P0.05)。结论 ALA可能通过抑制LPS诱导的Raw264.7细胞的ERK和NF-κB信号通路来抑制TNF-α释放。     

HPV 16 E6E7基因修饰树突状细胞疫苗诱导CTL致CaSki细胞凋亡体外实验研究

目的:采用人乳头状瘤-16(HPV-16)E6E7重组腺病毒(pAd-E6E7)转染树突状细胞(Dendritic cell,DC),观察基因修饰的DC疫苗诱导细胞毒性T淋巴细胞(Cytotoxic Tlymphocyte,CTL)致使CaSki细胞凋亡的效果。方法:将pAd-E6E7转染体外培养的小鼠未成熟树突状细胞制备DC疫苗,激光共聚焦显微镜观察转染的小鼠未成熟树突状细胞绿色荧光蛋白表达,流式细胞术检测转染前后小鼠树突状细胞表面标志物(CD40、CD86、MHCⅡ和CD11C)。DC疫苗诱导产生特异性细胞毒性T淋巴细胞,与CaSki细胞共培养后,采用DAPI、TUNEL及流式细胞术检测CaSki细胞凋亡情况。结果:pAd-E6E7成功转染体外培养的小鼠未成熟树突状细胞,体外转染效率约为40%～50%,成功制备了HPV16 E6E7基因修饰树突状细胞疫苗,诱导产生细胞毒性T淋巴细胞,经DAPI、TUNEL及流式细胞术检测证明CaSki出现凋亡。结论:以带有HPV16 E6E7基因的重组腺病毒载体转染DC制备基因修饰的DC疫苗,诱导CTL致使CaSki细胞出现凋亡。     

短发夹状RNA基因沉默补体受体C5aR及抑制LPS诱导的肾脏上皮细胞凋亡

目的:探讨短发夹状RNA基因沉默补体受体C5aR及抑制LPS诱导的肾脏上皮细胞凋亡的作用效果。方法:构建针对大鼠补体受体C5aR基因编码区的短发夹状RNA(shRNA)真核表达载体质粒pRNAT-U6.1-C5aR shRNA,采用电穿孔的方法转染RK3E细胞,经G418筛选后,形成稳定的表达C5aR shRNA的细胞系。实验分为3组,①正常对照组:未转染的RK3E细胞;②阴性对照组:转染空载体pRNAT-U6.1的RK3E细胞系;③实验组:转染C5aR shRNA的RK3E细胞系。经脂多糖(LPS)孵育12小时后,流式细胞仪检测各组细胞凋亡率,RT-PCR检测mRNA的表达,γ计数仪测定125I标记的C5a与RK3E的结合情况。结果:与正常对照组和阴性对照组相比,实验组的细胞凋亡率显著降低(P0.01),C5aR mRNA水平显著降低(P0.01),125I标记的C5a与RK3E结合活性显著下降。结论:针对C5aR的特异性短发夹RNA可以明显引起靶基因的沉默,进而抑制LPS诱导的肾脏上皮细胞凋亡的发生。     

RNAi介导Caspase-3基因及其抑制LPS诱导肾脏上皮细胞凋亡的研究

目的：探讨RNA干扰Caspase-3基因及抑制LPS诱导的肾脏上皮细胞凋亡的作用效果。方法：构建针对大鼠Caspase-3基因编码区的短发夹状RNA（shRNA）真核表达载体质粒pRNAT—U6．1-Caspase-3shRNA，用电穿孔法转染RK3E细胞，经G418筛选后，形成稳定的表达Caspase-3shRNA的细胞系。实验分为3组：①正常对照组：未转染的RK3E细胞；②阴性对照组：转染空载体pRNAT-U6．1的RK3E细胞系；③实验组：转染Caspase-3shRNA的RK3E细胞系。经脂多糖（LPS）孵育12小时后，流式细胞仪检测各组细胞凋亡率，RT-PCR检测mRNA的表达，以及各组Caspase-8蛋白的活性。结果：与正常对照组和阴性对照组相比，实验组的细胞凋亡率显著降低（P〈0．01），Caspase-3的mRNA水平和蛋白活性显著降低（P〈0．01）。结论：针对Caspase-3的特异性短发夹RNA可以明显引起靶基因的沉默，进而抑制LPS诱导的肾脏上皮细胞凋亡的发生。     

Activation of the RON receptor tyrosine kinase protects murine macrophages from apoptotic death induced by bacterial lipopolysaccharide

RON is a receptor tyrosine kinase activated by macrophage-stimulating protein. We demonstrate here that RON activation inhibits LPS-induced apoptosis of mouse peritoneal macrophages and Raw264.7 cells expressing RON or a constitutively active RON mutant. The antiapoptotic effect of RON was accompanied with the inhibition of LPS-induced production of nitric oxide (NO), a molecule responsible for LPS-induced cell apoptosis. This conclusion is supported by experiments using a chemical NO donor GSNO, in which RON activation directly blocked GSNO-induced apoptotic death of Raw264.7 cells and inhibited LPS-induced p53 accumulation. Furthermore, we showed that treatment of cells with wortmannin, which inhibits phosphatidylinositol (PI)-3 kinase, prevents the inhibitory effect of RON on LPS-induced macrophage apoptosis. These results were confirmed further by expression of a dominant inhibitory PI-3 kinase p85 subunit. These data suggest that by activating PI-3 kinase and inhibiting p53 accumulation, RON protects macrophage from apoptosis induced by LPS and NO. The antiapoptotic effect of RON might represent a novel mechanism for the survival of activated macrophages during inflammation.     

Mechanism of p38 MAP kinase activation in vivo

The p38 mitogen-activated protein kinase (MAPK) is activated in vitro by three different protein kinases: MKK3, MKK4, and MKK6. To examine the relative roles of these protein kinases in the mechanism of p38 MAP kinase activation in vivo, we examined the effect of disruption of the murine Mkk3, Mkk4, and Mkk6 genes on the p38 MAPK signaling pathway. We show that MKK3 and MKK6are essential for tumor necrosis factor-stimulated p38 MAPK activation. In contrast, ultraviolet radiation-stimulated p38 MAPK activation was mediated by MKK3, MKK4, and MKK6. Loss of p38 MAPK activation in the mutant cells was associated with defects in growth arrest and increased tumorigenesis. These data indicate that p38 MAPK is regulated by the coordinated and selective actions of three different protein kinases in response to cytokines and exposure to environmental stress.     

Caveolin-1 confers antiinflammatory effects in murine macrophages via the MKK3/p38 MAPK pathway

Caveolin-1 has been reported to regulate apoptosis, lipid metabolism, and endocytosis in macrophages. In the present study, we demonstrate that caveolin-1 can act as a potent immunomodulatory molecule. We first observed caveolin-1 expression in murine alveolar macrophages by Western blotting and immunofluorescence microscopy. Loss-of-function experiments using small interfering RNA showed that down regulating caveolin-1 expression in murine alveolar and peritoneal macrophages increased LPS-induced proinflammatory cytokine TNF-alpha and IL-6 production but decreased anti-inflammatory cytokine IL-10 production. Gain-of-function experiments demonstrated that overexpression of caveolin-1 in RAW264.7 cells decreased LPS-induced TNF-alpha and IL-6 production and augmented IL-10 production. p38 mitogen-activated protein kinase (MAPK) phosphorylation was increased by overexpressing caveolin-1 in RAW264.7 cells, whereas c-Jun N-terminal kinase, extracellular signal-regulated kinase MAPK, and Akt phosphorylation were inhibited. The antiinflammatory modulation of LPS-induced cytokine production by caveolin-1 was significantly abrogated by the administration of p38 inhibitor SB203580 in RAW264.7 cells. Peritoneal macrophages isolated from MKK3 null mice did not demonstrate any modulation of LPS-induced cytokine production by caveolin-1. LPS-induced activation of NF-kappaB and AP-1 determined by electrophoretic mobility shift assay were significantly reduced by overexpressing caveolin-1 in RAW264.7 cells. The reductions were attenuated by the administration of p38 inhibitor SB203580. Taken together, our data suggest that caveolin-1 acts as a potent immunomodulatory effector molecule in immune cells and that the regulation of LPS-induced cytokine production by caveolin-1 involves the MKK3/p38 MAPK pathway.     

Trps1 plays a pivotal role downstream of Gdf5 signaling in promoting chondrogenesis and apoptosis of ATDC5 cells

Tricho-rhino-phalangeal syndrome (TRPS) is an autosomal dominant skeletal disorder caused by mutations of TRPS1 . Based on the similar expression patterns of Trps1 and Gdf5, we hypothesized a possible functional interaction between these two molecules. Using a chondrogenic cell line (ATDC5), we investigated the association of Gdf5-mediated signaling pathways with Trps1 and the phenotypic changes of ATDC5 cells due to over-expression or suppression of Trps1. Treatment of cells with Gdf5 enhanced Trps1 protein levels and phosphorylation of p38 mitogen-activated protein kinase (MAPK) in a dose-dependent manner. Nuclear translocation of Trps1 was also induced by Gdf5. These effects were blocked by a dominant negative form of activin-linked kinase 6 (dn-Alk6) and by SB203580, an inhibitor of the p38 MAPK pathway. Conversely, Gdf5 expression was suppressed by the over-expression of Trps1. Trps1-overexpressing ATDC5 (O/E) cells differentiated into chondrocytes more quickly than mock-infected control cells, whereas cells transfected with dn-Alk6 showed slower differentiation. On the other hand, O/E cells showed an increase of apoptosis along with the up-regulation of cleaved caspase 3 and down-regulation of Bcl-2, whereas dn-Alk6 cells showed suppression of apoptosis. In conclusion, Trps1 acts downstream of the Gdf5 signaling pathway and promotes the differentiation and apoptosis of ATDC5 cells.     

Induction of inducible nitric oxide synthase-NO* by lipoarabinomannan of Mycobacterium tuberculosis is mediated by MEK1-ERK, MKK7-JNK, and NF-kappaB signaling pathways

Nitric oxide (NO*) expression by inducible nitric oxide synthase (iNOS) is an important host defense mechanism against Mycobacterium tuberculosis in mononuclear phagocytes. The objective of this investigation was to examine the role of mitogen-activated protein (MAP) kinase (MAPK) and nuclear factor kappaB (NF-kappaB) signaling pathways in the regulation of iNOS and NO* by a mycobacterial cell wall lipoglycan known as mannose-capped lipoarabinomannan (ManLAM). Specific pharmacologic inhibition of the extracellular-signal-regulated kinase (ERK) or NF-kappaB pathway revealed that both these signaling cascades were required in gamma interferon (IFN-gamma)-ManLAM-induced iNOS protein and NO2- expression in mouse macrophages. Transient cotransfection of dominant-negative protein mutants of the c-Jun NH2-terminal kinase (JNK) pathway revealed that the MAP kinase kinase 7 (MKK7)-JNK cascade also mediated IFN-gamma-ManLAM induction of iNOS promoter activity whereas MKK4 did not. Overexpression of null mutant IkappaBalpha, a potent inhibitor of NF-kappaB activation, confirmed that the IkappaBalpha kinase (IKK)-NF-kappaB signaling pathway enhanced IFN-gamma-ManLAM-induced iNOS promoter activity. By contrast, activated p38mapk inhibited iNOS induction. These results indicate that combined IFN-gamma and ManLAM stimulation induced iNOS and NO. expression and that MEK1-ERK, MKK7-JNK, IKK-NF-kappaB, and p38mapk signaling pathways play important regulatory roles.     

Rab7负向调控巨噬细胞中CpG诱导的细胞因子的表达

目的:研究Rab7过表达及失活突变(Rab7T22N)对CpG刺激的RAW264.7巨噬细胞中分泌细胞因子的影响。方法:采用RT-PCR和Real-time PCR检测RAW264.7细胞中Rab7在CpG刺激下表达模式。将Rab7真核表达质粒及失活突变质粒Rab7T22N通过脂质体法转染RAW264.7细胞,G418稳定筛选,Western法鉴定表达效果。用CpG刺激稳定表达Rab7的RAW264.7细胞系,RT-PCR和Real-time PCR检测细胞因子IL-6、IL-1β、IFN-β的表达量变化。结果:CpG刺激RAW264.7后,Rab7 mRNA表达水平逐渐增高,在8小时达到高峰,表达增高近4倍。Rab7过表达后,CpG刺激后产生的IL-6、IL-1β、IFN-β显著降低。巨噬细胞中Rab7失活突变后,在CpG刺激后IL-6、IL-1β、IFN-β的表达又显著增加。结论:CpG促进RAW264.7巨噬细胞中Rab7 mRNA的表达,Rab7抑制了CpG刺激的巨噬细胞中IL-6、IL-1β、IFN-β的表达,该抑制作用的发挥与其酶活性的GTP结合有关。该研究为进一步阐明Rab7在CpG/TLR9信号通路中的作用奠定了基础。     

Dissociated ROS production and ceramide generation in sulfasalazine-induced cell death in Raw 264.7 cells

Sulfasalazine (SSZ) is a drug used in inflammatory bowel disease, whose precise mechanism of action remains to be clarified. Here, we report that incubation of Raw 264.7 cells with SSZ but not salicylates [acetylsalicylic acid (ASA), 4-aminosalicylic acid (4-ASA), and 5-ASA] causes a mixed apoptotic and necrotic form of cell death. In contrast to its metabolites, sulfapyridine and 5-ASA, SSZ exposure in Raw 264.7 cells resulted in a threefold increase in ceramide generation, as well as a robust production of reactive oxygen species (ROS). However, inhibition of ceramide production by fumonisin B1 failed to attenuate cell death. Preincubation with catalase, cyclosporin A (CsA), and bongkrekic acid attenuated ROS production. When dead cells were quantified for apoptotic versus necrotic cell death, catalase and N-acetylcysteine reproducibly attenuated apoptosis, whereas CsA, in addition to reducing apoptosis, was observed to dramatically enhance necrosis. In conclusion, the cell-death response induced by SSZ in Raw 264.7 cells involves ROS in the apoptotic limb but is independent of ceramide formation.     

MAPK通路在晚期糖基化终产物诱导人脐静脉内皮细胞骨架结构改变中的作用

目的：探讨晚期糖基化终产物通过MAPK信号转导通路引起人脐静脉内皮细胞骨架结构改变的作用机制。方法：用胰酶消化法分离培养人脐静脉内皮细胞，以不同浓度的晚期糖基化终产物修饰的人血清白蛋白（AGE-HSA）与之作用不同时间，并选用不同的试剂以及主导激活或抑制的腺病毒突变体以阻断或激活MAPK通路，与对照组进行比较，采用免疫荧光染色法显示细胞骨架肌动蛋白F-actin的结构改变。结果：AGE-HSA以剂量和时间依赖的方式引起内皮细胞骨架蛋白F-actin结构的改变，未经修饰的HSA无此作用;p38通路的特异性抑制剂SB203580和ERK通路的特异性抑制剂PD98059均可抑制AGEs对细胞骨架的作用，而JNK通路抑制剂SP600125则无此作用；MKK6b、 MEK1结构活性型突变体的重组腺病毒可明显诱导细胞骨架改变，MKK7活性型则无此作用;且MKK6b、 MEK1无活性型突变体可明显抑制AGEs对细胞骨架的作用；p38α亚型的无活性突变体可阻断MKK6b结构活性型突变体诱导的细胞骨架改变。结论：AGE修饰蛋白通过MAPK家族中的p38和ERK信号转导通路引起内皮细胞骨架肌动蛋白F-actin的重组和再分布。