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1.
转染E1B55K基因提高Hep2细胞包装肠腺病毒Ad41的能力   总被引:2,自引:0,他引:2  
人F组腺病毒Ad40、Ad41难以在体外培养的细胞中传代,被称为难养腺病毒(Fastidious adenovirus).本研究观察了在Hep2细胞表达Ad41 E1B55K基因对Ad41复制的促进作用.从Ad41阳性粪便标本中用PCR的方法获得E1B55K基因,构建真核表达载体,转染Hep2细胞,筛选单克隆,用RT-PCR检测了E1B55K基因的表达.用引起293细胞完全CPE比较产毒量的方法对所得细胞克隆进行初步筛选,获得一株产毒相对较强的细胞Hep2-E1B#4.与对照细胞Hep2、Hep2-DNA3相比,等量Ad41接种Hep2-E1B#4产生的细胞病变效应(CPE)程度明显加深.用免疫细胞化学的方法测定产毒的感染滴度,等量Ad41接种后,Hep2-E1B#4产生的子代腺病毒滴度大于对照的9倍;半定量PCR测得Hep2-E1B#4子代病毒基因组拷贝数约为对照细胞的4倍.结果说明转染E1B55K基因促进了Ad41在Hep2细胞的复制,获得的Hep2-E1B#4细胞株可用于Ad41的分离、培养和体外扩增.  相似文献   

2.
Cdc55, a regulatory B subunit of the protein phosphatase 2A (PP2A) complex, plays various functions during mitosis. Sequestration of Cdc55 from the nucleus by Zds1 and Zds2 is important for robust activation of mitotic Cdk1 and mitotic progression in budding yeast. However, Zds1-family proteins are found only in fungi but not in higher eukaryotes. In animal cells, highly conserved ENSA/ARPP-19 family proteins bind and inhibit PP2A–B55 activity for mitotic entry.

In this study, we compared the relative contribution of Zds1/Zds2 and ENSA-family proteins Igo1/Igo2 on Cdc55 functions in budding yeast mitosis. We confirmed that Igo1/Igo2 can inhibit Cdc55 in early mitosis, but their contribution to Cdc55 regulation is relatively minor compared with the role of Zds1/Zds2. In contrast to Zds1, which primarily localized to the sites of cell polarity and in the cytoplasm, Igo1 is localized in the nucleus, suggesting that Igo1/Igo2 inhibit Cdc55 in a manner distinct from Zds1/Zds2.

Our analysis confirmed an evolutionarily conserved function of ENSA-family proteins in inhibiting PP2A-Cdc55, and we propose that Zds1-dependent sequestration of PP2A-Cdc55 from the nucleus is uniquely evolved to facilitate closed mitosis in fungal species.  相似文献   


3.
The directional migration of neutrophils towards inflammatory mediators, such as chemokines and cannabinoids, occurs via the activation of seven transmembrane G protein coupled receptors (7TM/GPCRs) and is a highly organized process. A crucial role for controlling neutrophil migration has been ascribed to the cannabinoid CB(2) receptor (CB(2)R), but additional modulatory sites distinct from CB(2)R have recently been suggested to impact CB(2)R-mediated effector functions in neutrophils. Here, we provide evidence that the recently de-orphanized 7TM/GPCR GPR55 potently modulates CB(2)R-mediated responses. We show that GPR55 is expressed in human blood neutrophils and its activation augments the migratory response towards the CB(2)R agonist 2-arachidonoylglycerol (2-AG), while inhibiting neutrophil degranulation and reactive oxygen species (ROS) production. Using HEK293 and HL60 cell lines, along with primary neutrophils, we show that GPR55 and CB(2)R interfere with each other's signaling pathways at the level of small GTPases, such as Rac2 and Cdc42. This ultimately leads to cellular polarization and efficient migration as well as abrogation of degranulation and ROS formation in neutrophils. Therefore, GPR55 limits the tissue-injuring inflammatory responses mediated by CB(2)R, while it synergizes with CB(2)R in recruiting neutrophils to sites of inflammation.  相似文献   

4.
PPP2R2C encodes a gamma isoform of the subunit B55 subfamily, which is a regulatory subunit of Protein phosphatase type 2A (PP2A). Our study shows that PPP2R2C is downregulated in glioma cells and human brain cancer patient samples. Overexpression of PPP2R2C inhibited cancer cell proliferation both in vitro and in vivo through the suppression of the activity of S6K in the mTOR pathway. Moreover, exogenous expression of PPP2R2C promoted the formation of a complex with the PP2A-C subunit to further enhance the binding of PP2A-C with S6K. Our results suggest that PPP2R2C is a potential tumor suppressor gene in human brain cancers. This study will provide novel insight into the development of therapeutic strategies in the treatment of human brain tumors.  相似文献   

5.
Recovery from DNA damage is critical for cell survival. However, serious damage cannot be repaired, leading to cell death for prevention of abnormal cell growth. Previously, we demonstrated that 4N-DNA accumulates via the initiation of an abnormal interphase without cytokinesis and that re-replication occurs during a prolonged recovery period in the presence of severe DNA damage in mitotic cells. Mitotic phosphorylated Plk1 is typically degraded during mitotic exit. However, Plk1 has unusually found to be dephosphorylated in mitotic slippage without cytokinesis during recovery from mitotic DNA damage. Here, we investigated how Plk1 dephosphorylation is established during recovery from mitotic DNA damage. Mitotic DNA damage activated ATM and Chk1/2 and repressed Cdk1 and Greatwall protein kinase, followed by PP2A activation through the dissociation of ENSA and PP2A-B55. Interaction between Plk1 and PP2A-B55α or PP2A-B55δ was strongly induced during recovery from mitotic DNA damage. Moreover, the depletion of PP2A-B55α and/or PP2A-B55δ by siRNA transfection led to the recovery of Plk1 phosphorylation and progression of the cell cycle into the G1 phase. Therefore, to adapt to severe DNA damage, the activated Greatwall/ENSA signaling pathway was repressed by ATM/Chk1/2, even in mitotic cells. Activation of the PP2A-B55 holoenzyme complex induced the dephosphorylation of Plk1 and Cdk1, and finally, mitotic slippage occurred without normal chromosome segregation and cytokinesis.  相似文献   

6.
7.
The possibility of using radiolabeled divalent cations to visualize nerve cell degeneration in the brain was investigated after intoxication with neurotoxins. At different survival times after the intracerebral injection of kainic acid or 6-hydroxydopamine, autoradiographs were made from brain sections of rats that had received 45CaCl2 intravenously 24 h before death. Brain sections, adjacent to those used for autoradiography, of the 6-hydroxydopamine-treated rats were used for histofluorescence of catecholamines to check the neurochemical effect of the treatment. These experiments show that radioactive Ca accumulates in brain tissue during a particular phase of degeneration. Not only could degenerating cell bodies be traced by 45Ca autoradiography, but also degenerating nerve terminals in the striato-nigral and nigro-striatal projection systems. In positron emission tomography (PET) studies, 55CoCl2 was used as a marker for Ca2+. Unilateral lesions of the cat forebrain, produced by kainic acid, could be imaged in vivo by PET with 55CoCl2. PET with this radiolabel may provide diagnostic potentials for human neurodegenerative disorders.  相似文献   

8.
Cancer stem cells are supposed to be resistant to apoptosis, but information for this is quite limited. Cancer stem cells are usually isolated as dye-effluxing cells with Hoechst 33342 staining, called side-population (SP) cells. Because Hoechst 33342 dye itself induces apoptosis, the SP cells isolated by such method are not suitable for evaluation of apoptosis. For accurate assessment, SP cells must be isolated without Hoechst 33342. Here, we found that CD55 was highly expressed in SP cells of two mammary gland carcinoma cell lines. Then, the high expression of CD55 was used for isolation of cancer stem cells among mammary carcinoma cell lines as a surrogate character. Cells expressing high level of CD55 (CD55(hi)) were resistant to apoptosis induced by serum depletion as in the case of SP cells. In ceramide-inducing apoptosis, CD55(hi) cells showed high tolerance. Anti-apoptotic molecules such as Bcl-2 were abundantly expressed in both SP cells and CD55(hi) cells. These findings indicated that SP cells as revealed to be CD55(hi) cells were tolerant to apoptosis. The high expression of CD55 may be a useful character for SP cells in evaluating their functions.  相似文献   

9.
Mantovani  G.  Macciò  A.  Lai  P.  Turnu  E.  Del Giacco  G. S. 《Cell biochemistry and biophysics》1994,24(1-3):301-305
The aim of the study was to evaluate the subset distribution and the IL-2 R p55–p75 subunit expression on unstimulated and phytohemagglutinin (PHA)-stimulated (at 3-d) peripheral blood mononuclear cells (PBMC), of patients with solid cancers of different sites. Indeed the expression of the two subunits of IL-2R is an essential prerequisite for The action of the IL-2 on CD8+, CD16+ lymphocytes as effectors in antitumor activity (LAK-cells). The subset distribution (CD3, CD4, CD8, CD16, DR) was assessed by cytofluorometry with specific monoclonal antibodies (MAbs); the p55 (CD25) and p75 subunit expression was evaluated by specific MAb (OKT26a and anti-p75). Ninety patients with advanced cancer (mainly non-small cell lung cancer [NSCLC], head and neck cancer, and gynecological cancer; mean age 55 yr; range 27–80) were studied. Thirty-five age- and sex-matched healthy subjects were studied as controls. Our data show that there is no significant difference in the subset distribution between cancer patients and controls. Furthermore, no difference has been found in the expression of p55 subunits on unstimulated PBMC between cancer patients and controls. No difference has been found in the expression of both p55 and p75 subunits on PHA-stimulated PBMC between cancer patients and controls. Our results can support the rationale for further clinical trials with IL-2 in solid malignancies.  相似文献   

10.
Although the importance of the extracellular signal-regulated kinase (ERK) pathway in regulating the transition from G1 to S has been extensively studied, its role during the G2/M transition is less well understood. Previous reports have shown that inhibition of the ERK pathway in mammalian cells delays entry as well as progression through mitosis, suggesting the existence of molecular targets of this pathway in M phase. In this report we employed 2-DE and MS to survey proteins and PTMs in the presence versus absence of MKK1/2 inhibitor. Targets of the ERK pathway in G2/M were identified as elongation factor 2 (EF2) and nuclear matrix protein, 55 kDa (Nmt55). Phosphorylation of each protein increased under conditions of ERK pathway inhibition, suggesting indirect control of these targets; regulation of EF2 was ascribed to phosphorylation and inactivation of upstream EF2 kinase, whereas regulation of Nmt55 was ascribed to a delay in normal mitotic phosphorylation and dephosphorylation. 2-DE Western blots probed using anti-phospho-Thr-Pro antibody demonstrated that the effect of ERK inhibition is not to delay the onset of phosphorylation controlled by cdc2 and other mitotic kinases, but rather to regulate a small subset of targets in M phase in a nonoverlapping manner with cdc2.  相似文献   

11.
The murine IL-3-dependent myeloid cell line 32D undergoes a rapid death when deprived of interleukin-3 (IL-3), a process that is suppressed or delayed by the constitutive expression of Bcl-2 or the Bcl-2-related Bcl-xL survival protein. The adenovirus type 5 E1B region encodes an E1B 55K protein, that has been reported to bind and inactivate the p53 protein that plays an important role in the induction of apoptosis. In order to explore the potential effect of the E1B 55K protein on IL-3 deprival-induced cell death, we have established 32D cell lines overexpressing the adenovirus E1B 55K protein and compared its ability to modulate the cell death with that of the human Bcl-2 protein. We observed that E1B 55K, as Bcl-2, delays the cell death caused by either IL-3-deprivation or DNA damage induced by gamma-irradiation. Cell-cycle analysis after IL-3 deprivation indicated that surviving Bcl-2 transfectants accumulate predominantly in the G0/G1 phase of the cell cycle, while E1B 55K transfectants survive in both G0/G1 and the S and G2/M phases of the cell cycle. zVAD-fmk, a broad caspase inhibitor, prevented chromatin condensation and fragmentation, but not cell death, suggesting that IL-3 deprivation induces a cell death program in which the caspases are dispensable. In contrast, both E1B 55K and Bcl-2 allowed cell survival and prevented the typical features of programmed cell death, such as phosphatidyl-serine exposure, loss of mitochondrial membrane potential, and chromatin condensation and fragmentation. Our findings indicate that the adenovirus 5 E1B 55K protein has the capability to act as a survival factor, and suggest that E1B 55K exerts its effect upstream of the activation of effector caspases, by preventing the loss of mitochondrial membrane potential induced by IL-3 deprivation.  相似文献   

12.
摘要 目的:探讨乳腺癌改良根治术患者术后复发转移的危险因素及血清糖类抗原125(CA125)、环加氧酶-2(COX-2)、可溶性肿瘤坏死因子受体P55(sTNFR-P55)的预测价值。方法:对2014年1月至2016年12月新疆医科大学第一附属医院收治的109例行乳腺癌改良根治术的乳腺癌患者进行前瞻性研究,所有患者术后均随访5年,其中2例失访,107例完成随访。根据5年内患者复发转移情况将其分为复发转移组(n=31)和未复发转移组(n=76)。收集患者入院时的临床病理资料,采用电化学发光法检测术前血清CA125,采用酶联免疫吸附法检测术前血清COX-2、sTNFR-P55。采用logistic回归模型分析患者术后复发转移的影响因素,绘制受试者工作特征(ROC)曲线评估血清CA125、COX-2、sTNFR-P55对术后复发转移的预测价值。结果:复发转移组肿瘤直径>5 cm、浸润性非特殊癌、脉管癌栓、雌激素受体(ER)/孕激素受体(PR)阴性、无内分泌治疗构成比、TNM分期IIIA期、腋窝淋巴结转移数量4~9个构成比高于未复发转移组(P<0.05)。复发转移组血清CA125、COX-2、sTNFR-P55水平高于未复发转移组(P<0.05)。多因素logistic回归分析结果显示,肿瘤直径>5 cm、浸润性非特殊癌、TNM分期IIIA期、脉管癌栓、腋窝淋巴结转移数量4~9个、CA125升高、COX-2升高、sTNFR-P55升高是乳腺癌改良根治术患者术后5年内复发转移的独立危险因素(OR=1.318、1.213、1.223、1.137、1.257、1.241、1.313、1.351,P<0.05)。血清CA125、COX-2、sTNFR-P55均可有效预测乳腺癌术后复发转移,曲线下面积(AUC)分别为0.803、0.749、0.761,三指标联合预测术后复发转移的AUC为0.915,灵敏度和特异度分别为0.94、0.83。结论:肿瘤直径、浸润性非特殊癌、TNM分期、脉管癌栓、腋窝淋巴结转移数量以及术前血清CA125、COX-2、sTNFR-P55异常升高是乳腺癌改良根治术患者术后5年内复发转移的危险因素,术前血清CA125、COX-2、sTNFR-P55联合检测可预测乳腺癌改良根治术后的复发转移风险。  相似文献   

13.
Friend spleen focus-forming virus (F-SFFV) is a replication-defective acutely leukemogenic mouse retrovirus and encodes an envelope protein (Env)-like membrane glycoprotein (gp55) in its defective env gene, which is responsible for the early stage of the viral leukemogenesis. Gp55 is a modified Env protein and contains a polytropic mink cell focus-inducing (MCF) murine leukemia virus (MuLV) Env gp70-derived sequence in its amino-terminal region. To evaluate the possibility that the presumed binding of gp55 to an MCF MuLV receptor protein has some role in leukemogenesis, we examined the biological activities of a mutant gp55 (XE gp55), which has a xenotropic MuLV Env gp70 amino-terminal region. XE gp55 displayed almost the same biological activities as the wild-type gp55, excluding the above possibility.  相似文献   

14.
Interaction of nucleoredoxin with protein phosphatase 2A   总被引:1,自引:0,他引:1  
A trimeric protein phosphatase 2A (PP2A(T55)) composed of the catalytic (PP2Ac), structural (PR65/A), and regulatory (PR55/B) subunits was isolated from rabbit skeletal muscle by thiophosphorylase affinity chromatography, and contained two additional proteins of 54 and 55 kDa, respectively. The 54 kDa protein was identified as eukaryotic translation termination factor 1 (eRF1) and as a PP2A interacting protein. The 55 kDa protein is now identified as nucleoredoxin (NRX). The formation of a complex between GST-NRX, PP2A(C) and PP2A(D) was demonstrated by pull-down experiments with purified forms of PP2A, and by immunoprecipitation of HA-tagged NRX expressed in HEK293 cells complexed endogenous PP2A subunits. Analysis of PP2A activity in the presence of GST-NRX showed that NRX competed with polycations for both stimulatory and inhibitory effects on different forms of PP2A.  相似文献   

15.
Polypeptide chain fragments of recombinant transthyretin (TTR) with leucine-55 substituted by proline (L55P), which are involved in abnormal fibrillogenesis of this protein, were studied. No fibrils were produced in purified preparations of TTR(L55P) under the optimum conditions for fibrillogenesis but in absence of protease inhibitors. The ability of TTR for fibrillogenesis was lost because of a limited proteolysis resulting in detachment of the TTR polypeptide chain C-terminal fragment of approximately 18 amino acid residues in length. This proteolysis seemed to occur with involvement of a bacterial serine endopeptidase sohB (EC 3.4.21), which was identified in TTR preparations by the MALDI-TOF method. The presence of the C-terminal fragment of the TTR polypeptide chain seems to be crucial for production of abnormal fibrils.  相似文献   

16.
The role of glia maturation factor (GMF) in myelin oligodendrocyte glycoprotein (MOG) 35-55 peptide-induced experimental autoimmune encephalomyelitis (EAE) was investigated using GMF-deficient (GMF-KO) mice. We demonstrate that GMF-KO mice were resistant to the MOG 35-55 peptide-induced EAE as compared to wild type (Wt) mice (two in eight versus 10 in 10). Next, we examined the effect of administration of recombinant human GMF (rGMF) on MOG 35-55 peptide-induced EAE in mice. Daily administration of rGMF, staring days 1-14, resulted in significant exacerbation of clinical symptoms. Following rGMF injections, both GMF-KO (six in eight) and Wt mice (eight in eight) developed severe EAE (maximal clinical score of 3.5-4.0) with high frequency. The histological examination revealed severe infiltration of inflammatory cells in the spinal cord of MOG-immunized Wt mice while the resistance to EAE in GMF-KO mice was characterized by the absence of inflammatory cells. Administration of rGMF in Wt mice and GMF-KO mice resulted in a significant increase in infiltrating cells in the spinal cord following MOG-immunizations. We also evaluated cytokines and chemokines production as parameters of severity of inflammation in the spinal cord of Wt versus GMF-KO mice with and without GMF-reconstitution following MOG-immunizations. Cytokines (TNF-α, IFN-γ, IL-1β, IL-6) and chemokines (CCL2, CCL3, CXCL10, GM-CSF) production were significantly greater in Wt mice than in GMF-KO mice following MOG-immunization. Furthermore, the reconstitution experiment with rGMF showed that the administration of rGMF in both, Wt mice and GMF-KO mice produced significant increase in the GMF-mediated cytokine/chemokine production.  相似文献   

17.
Undecaprenyl phosphate (C55-P) acts as carrier lipid in the synthesis of peptidoglycan, which is de novo synthesized from dephosphorylation of undecaprenyl pyrophosphate (C55-PP). The phosphatidylglycerol phosphate phosphatase B (PgpB) catalyzes the dephosphorylation of C55-PP and forms C55-P. As no structural study has been made regarding the binding of C55-PP to PgpB, in the current study, in silico molecular docking, followed by 150 ns molecular dynamics simulation of the putative binding complex in membrane/solvent environment has been performed to understand conformational dynamics. Results are compared with simulated apo form and PE inhibitor-bound form. Analysis of correlated residual fluctuation network in apo form, C55-PP bound and PE inhibitor-bound form suggests that difference in dynamic coupling between TM domain and α2 and α3 helix of periplasmic domain provides ligand binding to facilitate catalysis or to show inhibitory activity. Distance distribution in catalytic residual pair, H207-R104; H207-R201 and H207-D211 which stabilizes phosphate-enzyme intermediate shows a narrow peak in 2.4–3.6 Å in substrate-bound compared to apo form. Binding interactions and binding free energy analyses complement the partial inhibition of PE where PE has less binding free energy compared to the C55-PP substrate as well as the difference in binding interaction with catalytic pocket. Thus, the present study provides how substrate binding couples the movement in TM domain and periplasmic domain which might help in the understanding of active site communication in PgpB. C55-PP phosphatase interactions with a catalytic pocket of PgpB provide new insight for designing drugs against bacterial infection.  相似文献   

18.
Zhang ZL  Zou WG  Luo CX  Li BH  Wang JH  Sun LY  Qian QJ  Liu XY 《Cell research》2003,13(6):481-489
ONYX-015 is an attractive therapeutic adenovirus for cancer because it can selectively replicate in tumor cells and kill them. To date, clinical trials of this adenovirus have demonstrated marked safety but not potent enough when it was used alone. In this paper, we put forward a novel concept of Gene-ViroTherapy strategy and in this way, we constructed an armed therapeutic oncolytic adenovirus system, ZD55-gene, which is not only deleted of E1B 55-kD gene similar to ONYX-015, but also armed with foreign antitumor gene. ZD55-gene exhibited similar cytopathic effects and replication kinetics to that of ONYX-015 in vitro. Importantly, the carried gene is expressed and the expression level can increase with the replication of virus. Consequently, a significant antitumoral efficacy was observed when ZD55-CD/5-FU was used as an example in nude mice with subcutaneous human SW620 colon cancer. Our data demonstrated that ZD55-gene, which utilizing the Gene-Viro Therapy strategy, is more efficacious than each individual component in vivo.  相似文献   

19.
Entry into mitosis is mediated by the phosphorylation of key cell cycle regulators by cyclin-dependent kinase 1 (Cdk1). In Xenopus embryos, the M-phase-promoting activity of Cdk1 is antagonized by protein phosphatase PP2A-B55. Hence, to ensure robust cell cycle transitions, Cdk1 and PP2A-B55 must be regulated so that their activities are mutually exclusive. The mechanism underlying PP2A-B55 inactivation at mitotic entry is well understood: Cdk1-activated Greatwall (Gwl) kinase phosphorylates Ensa/Arpp19, thereby enabling them to bind to and inhibit PP2A-B55. However, the re-activation of PP2A-B55 during mitotic exit, which is essential for cell cycle progression, is less well understood. Here, we identify protein phosphatase PP1 as an essential component of the PP2A-B55 re-activation pathway in Xenopus embryo extracts. PP1 initiates the re-activation of PP2A-B55 by dephosphorylating Gwl. We provide evidence that PP1 targets the auto-phosphorylation site of Gwl, resulting in efficient Gwl inactivation. This step is necessary to facilitate subsequent complete dephosphorylation of Gwl by PP2A-B55. Thus, by identifying PP1 as the phosphatase initiating Gwl inactivation, our study provides the molecular explanation for how Cdk1 inactivation is coupled to PP2A-B55 re-activation at mitotic exit.  相似文献   

20.
目的:探讨人腺病毒55型感染肺部病变与外周血淋巴细胞改变的关系及致病意义。方法:以50例经胸部CT证实为腺病毒肺炎的患者为研究对象(肺炎组),调查其外周血细胞及T淋巴细胞亚群变化情况,并与同期腺病毒55型感染未出现肺部病变的患者30例(非肺炎组)对照;亚组分析50例肺炎组中多肺叶病变与单肺叶病变患者之间T淋巴细胞变化的差异。结果:与非肺炎组患者相比,肺炎组患者急性期外周血淋巴细胞比例明显降低、单核细胞比例明显升高(P0.01);肺炎组CD3+T淋巴细胞比例、CD3+CD4+T淋巴细胞比例及CD4/CD8比值较非肺炎组均有明显降低(P0.01)。亚组分析显示,肺炎组患者肺部病变范围不同,T淋巴细胞亚群的变化亦有差异,多肺叶病变组患者CD3+CD8+T淋巴细胞比例较单肺叶病变组明显升高、CD4/CD8比值较单肺叶病变组明显降低(P0.05)。结论:HAdv-55感染引起肺炎病变时,宿主存在明显的细胞免疫功能受损,且与肺部病变程度有一定正相关。  相似文献   

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