miR-21通过PI3K/Akt通路抑制猪瘟病毒复制的机制的研究

为探索miR-21调控猪瘟病毒(CSFV)复制的分子机制,本实验采用猪瘟病毒感染体外培养的PK-15细胞,采用RT-PCR、western blot等方法检测miR-21表达、猪瘟病毒复制、PI3K/Akt通路变化及其三者之间的联系。结果表明,猪瘟病毒感染导致细胞miR-21表达水平下调,而PI3K/Akt通路相关因子磷酸化Akt蛋白表达显著上调。将miR-21类似物转染细胞后,猪瘟病毒滴度和RNA水平明显降低,而且PI3K/Akt通路受到阻遏。然而,采用阻断剂LY294002阻断细胞PI3K/Akt通路,结果显示,猪瘟病毒复制有所减弱,但作用不显著,而miR-21抑制猪瘟病毒复制的作用明显减弱。以上结果表明,miR-21可以通过PI3K/Akt通路抑制猪瘟病毒复制。     

禽呼肠孤病毒蛋白质启动PI3K/Akt信号通路的分析

旨在找出激活PI3K/Akt信号通路的禽呼肠孤病毒(ARV)蛋白质。选取ARV中潜在具有激活PI3K/Akt信号通路活性的σA、σNS、μA、μB和μNS蛋白作为研究对象,将这5个基因克隆到真核表达载体pcAGEN,成功构建重组质粒σA-pcAGEN、σNS-pcAGEN、μA-pcAGEN、μB-pcAGEN和μNS-pcAGEN。将构建的重组质粒转染Vero细胞,采用间接免疫荧光和Western blot检测目的蛋白质的表达,并通过流式细胞术和Western blot,检测转染后Vero细胞磷酸化Akt(P-Akt)的表达量。结果显示,5个目的蛋白质均得到表达。转染σA-pcAGEN或σNS-pcAGEN的Vero细胞,P-Akt的表达量明显升高,而使用PI3K特异性抑制剂LY294002则能抑制P-Akt的表达量明显升高。结果表明,ARV的σA蛋白和σNS蛋白能激活细胞的PI3K/Akt信号通路。     

禽呼肠孤病毒σA和σNS蛋白激活PI3K/Akt信号通路的研究

旨在探讨禽呼肠孤病毒(ARV)的σA和σNS蛋白是否是通过PXXP或YXXXM基序来激活PI3K/Akt信号通路的。作者采用重叠延伸PCR的方法,将σA和σNS基因的PXXP或YXXXM基序进行突变后构建了重组质粒,并在Vero细胞中进行了表达。通过流式细胞术和Western blot,检测转染后Vero细胞磷酸化Akt(P-Akt)的表达量,并与野生型σA和σNS蛋白激活的P-Akt表达量进行比较。结果显示,σA和σNS基因均得到了表达,σA基因的110—114和114—117位的PXXP基序突变后,Vero细胞P-Akt的表达量明显下降。可见,ARV的σA蛋白,是通过PXXP基序来激活PI3K/Akt信号通路的。本研究从细胞信号转导角度揭示了ARV与宿主相互作用的机制,也为寻找抗ARV药物作用靶标提供了新的思路。     

猪瘟病毒非结构蛋白NS4B与宿主蛋白相互作用的研究进展

猪瘟病毒(CSFV)是一种可感染猪只并引起典型或慢性猪瘟(CSF)的单链RNA包膜病毒,严重影响动物的健康和养猪业的经济发展。CSFV自身编码的结构蛋白和非结构蛋白可与宿主蛋白相互作用,促进病毒自身的复制、翻译和增殖,并影响病毒毒力和免疫反应等。CSFV的非结构蛋白NS4B在病毒生命周期中发挥重要作用,其自身结构上含有多种特定区域靶点,可与多种蛋白发生相互作用;其作为CSFV复制体碳价结构最重要的组成部分,还可被非结构蛋白NS3切割,在细胞内与CSFV自身蛋白或其他宿主蛋白,如核糖体蛋白侧柄亚基P1(RPLP1)、铁蛋白重链(FHC)、Rab蛋白22a(Rab22a)、脂肪酸合成酶(FASN)、线粒体抗病毒信号蛋白(MAVS)、肿瘤易感基因101(Tsg101)蛋白和猪指环蛋白114(pRNF114)等相互作用。本文对CSFV非结构蛋白NS4B的结构功能以及与宿主蛋白发生相互作用的研究进展进行概述,以期为CSFV致病机理研究和感染防控提供理论帮助。     

猪瘟病毒衣壳蛋白与宿主细胞核仁素蛋白相互作用

为鉴定猪瘟病毒(CSFV)衣壳蛋白(C)与宿主细胞核仁素(NCL)蛋白的相互作用,本研究将重组质粒p EGFP-CSFV-C转染至猪睾丸细胞(ST)中,采用GST pull-down和免疫共沉淀方法沉淀ST细胞中的NCL蛋白,通过共聚焦显微镜分析C蛋白和NCL蛋白的共定位情况。结果表明,CSFV C蛋白与NCL蛋白在核仁中存在共定位现象,并且在体外和转染细胞中均存在相互作用。NCL蛋白被抑制后,CSFV的复制能力下降。本研究为进一步分析C蛋白核转运机制以及在CSFV复制过程中的功能提供了实验依据。     

猪瘟病毒对ST细胞NF-κB信号通路炎性因子表达量的影响

探讨猪瘟病毒(CSFV)感染猪睾丸上皮细胞系(ST)对核因子-κB(NF-κB)信号通路相关炎性因子的表达。分别收集CSFV感染4、8、12、16、24、48 h的ST细胞,建立正常对照组和CSFV感染各试验组。荧光定量PCR(qPCR)法检测NF-кB通路相关炎性因子CHUK、IKBKB、NFKBIA、RelA基因mRNA表达量的变化,Western blot检测p65蛋白在核中的表达。NFKBIA、IKBKB基因的转录水平差异显著(P0.05);RelA基因的表达差异不显著(P0.05);CHUK基因在ST细胞感染CSFV后,转录水平差异显著(P0.05),Western blot试验显示,p65入核。CSFV感染ST细胞后,NF-κB的经典信号通路和非经典信号通路的均被激活,初步探索了机体感染CSFV对NF-κB通路上、下游的影响,为猪瘟的有效防控提供理论依据。     

猪瘟病毒亚基因复制子及其细胞系的构建

为探索猪瘟病毒(CSFV)的复制机理,本实验在前期CSFV流行株GD53全基因组测序的基础上,利用新霉素抗性基因(Neor)替换病毒结构蛋白基因以构建CSFV GD53株的亚基因组复制子(GD53-SGR)。首先构建含有T7-5'UTR-N~(pro)-Neor-EMCV/IRES-NS2-NS3-NS4A-NS4B-NS5A-NS5B-3'UTR的重组质粒pc DNA-GD53-SGR,将其利用T7 RNA聚合酶经体外转录制备的RNA转录本转染猪睾丸细胞系(ST)后,利用G418筛选含有GD53-SGR的ST细胞,构建ST-GD53-SGR细胞系。酶切鉴定及测序结果表明,重组质粒pc DNA-GD53-SGR构建正确,利用T7 RNA聚合酶体外转录后获得了与预期大小一致的GD53-SGR RNA。经RT-PCR和间接免疫荧光鉴定结果表明,获得了含有GD53-SGR的ST细胞系。本研究构建的CSFV ST-GD53-SGR细胞系有助于进一步了解CSFV非结构蛋白的功能,同时为CSFV的复制机制研究及抗病毒药物的研发奠定基础。     

猪瘟病毒与宿主蛋白相互作用的研究进展

猪瘟是一种高度传染性和致死性的病毒性疾病,给全球养猪业带来严重的经济损失。疫苗免疫是预防该病的主要手段,目前为止尚未研究出针对猪瘟病毒(CSFV)的特异性治疗药物。CSFV是一种专性细胞内寄生物,其复制严格依赖于宿主细胞,病毒与宿主细胞因子的相互作用关系决定了病毒感染、复制和致病的分子基础,因此设计针对相互作用的病毒蛋白或宿主蛋白的药物有可能治疗CSFV引起的疾病。本文对CSFV与宿主蛋白相互作用及其机制进行了综述,为猪瘟的预防及治疗提供理论依据。     

猪瘟病毒荧光定量PCR的建立及对病毒体外复制动态的研究

为了了解猪瘟病毒(CSFV)在PK-15细胞上的增殖规律。根据GenBank中CSFV Shimen毒株的NS5A基因保守区域序列,设计1对特异性引物,以CSFV总RNA为反转录模板,经优化反应条件,建立了基于实时荧光定量PCR技术的CSFV检测方法,并对其进行了敏感性、特异性、重复性试验,结果显示,该方法重复性好、特异性强,最低检测模板浓度为10拷贝/μL,并且CSFV的最低检测限为1 TCID_(50 )/mL。利用所建立的方法研究CSFV在PK-15细胞上清中的增殖动态,并与TCID_(50)方法绘制的复制动态曲线进行比较。结果显示,两种方法测定的CSFV在PK-15细胞上的复制动态具有一定的平行关系,该方法为研究猪瘟病毒的致病机理及利用体外细胞培养毒生产疫苗提供了试验依据。     

猪瘟病毒感染细胞中分子伴侣Jiv基因的表达检测与分析

Jiv蛋白是与猪瘟病毒(CSFV)细胞内复制密切相关的伴侣分子,为探究Jiv在CSFV感染细胞内的表达规律,应用实时荧光定量RT-PCR分别对3个猪源细胞株(SUVEC、PK-15、ST)在感染CSFV后不同时间Jiv和CSFV基因表达进行检测,分析两者的相关性。结果显示,3种猪源细胞株的Jiv和CSFV的基因在0~72h的表达逐步上调,72h~96h出现下降,二者变化趋势基本一致;此外,Jiv基因在0~48h上调幅度较其他时间段更为显著,ST细胞在不同时间段的Jiv表达均高于同时段的其他两种细胞,与ST细胞中CSFV复制趋势一致。结果表明,在CSFV感染细胞中Jiv基因的表达与CSFV复制呈正相关,即CSFV复制水平越高,Jiv基因表达水平也越高。本研究初步探明细胞Jiv蛋白在CSFV复制中的调节作用,为进一步明确Jiv蛋白参与CSFV复制的机制提供了新的资料。     

Inability of NS1 protein from an H5N1 influenza virus to activate PI3K/Akt signaling pathway correlates to the enhanced virus replication upon PI3K inhibition

Background

Phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway, activated during influenza A virus infection, can promote viral replication via multiple mechanisms. Direct binding of NS1 protein to p85β subunit of PI3K is required for activation of PI3K/Akt signaling. Binding and subsequent activation of PI3K is believed to be a conserved character of influenza A virus NS1 protein. Sequence variation of NS1 proteins in different influenza A viruses led us to investigate possible deviation from the conservativeness.

Results

In the present study, NS1 proteins from four different influenza A virus subtypes/strains were tested for their ability to bind p85β subunit of PI3K and to activate PI3K/Akt. All NS1 proteins efficiently bound to p85β and activated PI3K/Akt, with the exception of NS1 protein from an H5N1 virus (A/Chicken/Guangdong/1/05, abbreviated as GD05), which bound to p85β but failed to activate PI3K/Akt, implying that as-yet-unidentified domain(s) in NS1 may alternatively mediate the activation of PI3K. Moreover, PI3K inhibitor, {"type":"entrez-nucleotide","attrs":{"text":"LY294002","term_id":"1257998346","term_text":"LY294002"}}LY294002, did not suppress but significantly increased the replication of GD05 virus.

Conclusions

Our study indicates that activation of PI3K/Akt by NS1 protein is not highly conserved among influenza A viruses and inhibition of the PI3K/Akt pathway as an anti-influenza strategy may not work for all influenza A viruses.     

Ankyrin repeat and suppressor of cytokine signaling (SOCS) box-containing protein (ASB) 15 alters differentiation of mouse C2C12 myoblasts and phosphorylation of mitogen-activated protein kinase and Akt

Ankyrin repeat and suppressor of cytokine signaling box-containing protein (ASB) 15 is a novel ASB gene family member predominantly expressed in skeletal muscle. We have previously reported that overexpression of ASB15 delays differentiation and alters protein turnover in mouse C(2)C(12) myoblasts. However, the extent of ASB15 regulation of differentiation and molecular pathways underlying this activity are unknown. The extracellular signal-regulated kinase (Erk) 1/2 and phosphatidylinositol-3 kinase-Akt (PI3K/Akt; Akt is also known as protein kinase B) signaling pathways have a role in skeletal muscle growth. Activation (phosphorylation) of the Erk1/2 signaling pathway promotes proliferation, whereas activation of the PI3K/Akt signaling pathway promotes myoblast differentiation. Accordingly, we tested the hypothesis that ASB15 controls myoblast differentiation through its regulation of these kinases. Stably transfected myoblasts overexpressing ASB15 (ASB15+) demonstrated decreased differentiation, whereas attenuation of ASB15 expression (ASB15-) increased differentiation. However, ASB15+ cells had less abundance of the phosphorylated mitogen-activated protein kinase (active) form, despite decreased differentiation relative to control myoblasts (ASB15Con). The mitogen-activated protein kinase kinase inhibitor, U0126, effectively decreased mitogen-activated protein kinase phosphorylation and stimulated differentiation in ASB15- and ASB15Con cells. However, inhibition of the Erk1/2 pathway was unable to overcome the inhibitory effect of overexpressing ASB15 on differentiation (ASB15+), suggesting that the Erk1/2 pathway is likely not the predominant mediator of ASB15 activity on differentiation. Expression of ASB15 also altered phosphorylation of the PI3K/Akt pathway, as ASB15+ and ASB15- cells had decreased and increased Akt phosphorylation, respectively. These data were consistent with observed differences in differentiation. Administration of IGF-I, a PI3K/Akt activator, in ASB15+ was able to partially override the previously observed phenotype of delayed differentiation, whereas administration of the PI3K/ Akt inhibitor, LY294002, decreased phosphorylation of Akt and differentiation of all cell lines similar to the untreated ASB15+ myoblasts. These results provide initial evidence that ASB15 has a role in early myoblast differentiation and that its effects may be mediated in part by the PI3K/Akt signal transduction pathway.     

Biphasic activation of PI3K/Akt and MAPK/Erk1/2 signaling pathways in bovine herpesvirus type 1 infection of MDBK cells

ABSTRACT: Many viruses have been known to control key cellular signaling pathways to facilitate the virus infection. The possible involvement of signaling pathways in bovine herpesvirus type 1 (BoHV-1) infection is unknown. This study indicated that infection of MDBK cells with BoHV-1 induced an early-stage transient and a late-stage sustained activation of both phosphatidylinositol 3-kinase (PI3K)/Akt and mitogen activated protein kinases/extracellular signal-regulated kinase 1/2 (MAPK/Erk1/2) signaling pathways. Analysis with the stimulation of UV-irradiated virus indicated that the virus binding and/or entry process was enough to trigger the early phase activations, while the late phase activations were viral protein expression dependent. Biphasic activation of both pathways was suppressed by the selective inhibitor, Ly294002 for PI3K and U0126 for MAPK kinase (MEK1/2), respectively. Furthermore, treatment of MDBK cells with Ly294002 caused a 1.5-log reduction in virus titer, while U0126 had little effect on the virus production. In addition, the inhibition effect of Ly294002 mainly occurred at the post-entry stage of the virus replication cycle. This revealed for the first time that BoHV-1 actively induced both PI3K/Akt and MAPK/Erk1/2 signaling pathways, and the activation of PI3K was important for fully efficient replication, especially for the post-entry stage.     

PRV感染三叉神经节细胞对PI3K/Akt信号通路的影响及其调控凋亡

以小鼠三叉神经节(TG)原代细胞为基础,应用实时荧光定量PCR(q-PCR)、Western blot等方法检测伪狂犬病病毒(pseudorabies virus,PRV)(MOI=1)感染TG细胞后不同时间点PI3K、Akt基因的转录水平和蛋白表达情况.PRV感染TG细胞后,利用PI3K特异性抑制剂LY294002处...     

乳酸菌发酵饲料对SPF鸡免疫功能的影响

本试验旨在研究乳酸菌发酵饲料对SPF鸡免疫功能和磷脂酰肌醇三激酶/蛋白激酶B(PI3K/Akt)信号通路的影响。选取14日龄无特定病原体(SPF)雏鸡120羽,随机分为4组,每组5个重复,每个重复6羽。对照组饲喂基础饲料,发酵饲料组饲喂乳酸菌发酵饲料,基础阻断剂组为基础饲料加PI3K阻断剂组,乳酸菌阻断剂组为乳酸菌发酵饲料加PI3K阻断剂。试验期21 d。结果表明:发酵饲料组与对照组、乳酸菌阻断剂组与基础阻断剂组比较,乳酸菌发酵饲料可降低雏鸡耗料增重比(P<0.05),提高日增重、T淋巴细胞转化率、B淋巴细胞转化率、白细胞介素-2(IL-2)、白细胞介素-6(IL-6)、干扰素-α(IFN-α)、免疫球蛋白M(IgM)、免疫球蛋白A(IgA)和免疫球蛋白G(IgG)含量(P<0.05),提高雏鸡新城疫抗体(NDV-Ab)水平(P<0.05),提高雏鸡脾脏中PI3K、Akt mRNA和蛋白表达量(P<0.05);基础阻断剂组与对照组、乳酸菌阻断剂组与发酵饲料组比较,PI3K阻断剂可以提高雏鸡耗料增重比(P<0.05),降低日增重、T淋巴细胞转化率、B淋巴细胞转化率、IL-2、IL-6、IFN-α、IgM、IgA和IgG含量(P<0.05),降低雏鸡NDV-Ab水平(P<0.05),降低雏鸡脾脏中PI3K、Akt mRNA和蛋白表达量(P<0.05)。由此可见,乳酸菌发酵饲料可能是通过激活PI3K/Akt信号通路来提高SPF雏鸡的免疫功能。     

Inhibition of PI3K‐Akt‐mTOR signal pathway dismissed the stimulation of glucose on goose liver cell growth

In the formation of goose fatty liver induced by a high‐carbohydrate diet, it is characterized by the quick cell growth of liver. The carbohydrate is mostly digested and absorbed in the small intestine by the form of glucose. Recent studies have suggested a crucial role for PI3K‐Akt‐mTOR pathway in regulating cell proliferation, and then we speculate that PI3K‐Akt‐mTOR pathway may mediate glucose‐induced liver cell proliferation. Goose primary hepatocytes were isolated and incubated in either no addition as a control or glucose or PI3K‐Akt‐mTOR pathway inhibitors or cotreatment with glucose and PI3K‐Akt‐mTOR pathway inhibitors. The results firstly showed that 35 mmol/l glucose stimulated the mRNA level and protein content of factors involved in PI3K‐Akt‐mTOR signal pathway in goose primary hepatocytes. Secondly, 35 mmol/l glucose evidently changed the cell cycle PI index and protein expression of cyclin D1. Meanwhile, the upregulation of 35 mmol/l glucose on the DNA synthesis rate, cell cycle PI index, the mRNA expression, protein content and protein expression of factors involved in the cell proliferation was decreased significantly by the inhibitors of PI3K‐Akt‐mTOR pathway, LY294002, rapamycin or NVP‐BEZ235. In summary, glucose could stimulate the cell proliferation, and the PI3K‐Akt‐mTOR pathway inhibitors could dismiss glucose‐induced the upregulation of cell proliferation in goose primary hepatocyte.     

IGF-I retards proper development of acinar structures formed by bovine mammary epithelial cells via sustained activation of Akt kinase

Insulin-like growth factor-I is involved in mammary gland development, promoting proliferation and inhibiting apoptosis of mammary epithelial cells (MECs). Mitogenic actions of IGF-I are mainly mediated by the phosphatidylinositol-3 kinase (PI3K)/Akt signaling pathway. We have found that in the presence of IGF-I bovine BME-UV1 MECs cultured on reconstituted basement membrane form large spheroids with disrupted polarity and no cavity in the center. These cells showed enhanced phosphorylation of Akt, decreased level of cleaved caspase-3, and sustained proliferative activity throughout the 16-d period of 3-dimensional culture. Inhibition of the PI3K/Akt pathway by a specific inhibitor of PI3K, LY294002, resulted in the restoration of the normal acinar phenotype. However, this effect was noted only when LY294002 was added in the second week of 3-dimensional culture, which corresponded with the time of cell cycle arrest and polarity formation under control conditions. Normal development of acini was also obtained when BME-UV1 cells were treated simultaneously with IGF-I and 17β-estradiol. The addition of 17β-estradiol regulated Akt activation, enabling the subsequent initiation of polarization processes. 17β-Estradiol also increased the level of IGFBP-3 protein in MECs cultured on Matrigel in the presence of IGF-I. The presented results indicate important interactions between signaling pathways activated by estrogen and IGF-I, which regulate alveologenesis in bovine mammary gland.     

猪瘟病毒石门株NS3蛋白的原核表达及其抗体检测间接ELISA的建立

为配合猪瘟新型疫苗的研发,建立了猪瘟病毒NS3蛋白抗体检测间接ELISA,以期达到有效区分新型疫苗免疫猪与自然感染猪(包括常规疫苗接种猪)的目的。以接种猪瘟病毒(CSFV)石门株的PK-15细胞为模板提取总RNA,经特异性PCR扩增获得长度为2 049bp的CSFV NS3基因,将其克隆至插入了具有自聚集自切割功能短肽的原核表达载体pET-32a(+),在大肠埃希菌Rosetta(DE3)中优化表达CSFV石门株NS3基因。Western blot分析表明重组蛋白NS3具有反应原性。将纯化的重组蛋白NS3作为包被抗原建立检测CSFV NS3抗体的间接ELISA,以美国爱德士(Idexx)猪瘟病毒抗体检测试剂盒抗体检测结果为标准,对502份血清样品进行检测。结果表明,所建立方法的特异性为96.9%,敏感性为89.7%,总符合率为95.8%,为猪瘟新型疫苗的推广应用提供了血清学检测方法。     

Characterization of NS3, NS5A and NS5B of classical swine fever virus through mutation and complementation analysis

In order to get further insight into the organization of the pestiviral replication machinery, characterization of NS3, NS5A and NS5B of classical swine fever virus (CSFV) through mutation and complementation analysis was performed. Mutation analysis in genomic replicons and subgenomic replicons indicated importance of the GDD motif in NS5B, the DEYH motif in NS3 and the conserved sequence C2717-C2740-C2742-C2767 in the NS5A for CSFV recover and viral RNA synthesis. Complementation experiments were performed between subgenomic replicons, between RNA replicons or between RNA replicon and expressed nonstructural protein. Rescue of virus and recover of viral RNA synthesis were examined in these complementation experiments. Results showed that mutations within NS5A, neither NS5B nor NS3, can be trans-complemented, strongly suggesting that NS5B and NS3 function in cis mode for regulation of replication. We assumed that the necessary membrane association of CSFV NS5B and NS3 could occur only when they are being translated and originated from an identical translation template, with the exception of NS5A whose membrane association might occur post-translationally.