Cytoplasmic and nuclear virus-specific proteins in influenza virus-infected MDCK cells

Four virus-specific proteins were identified in nuclei purified from influenza virusinfected cells: the nucleocapsid protein (NP); two nonstructural proteins of 24,500 daltons (NS₁) and 11,000 daltons (NS₂) molecular weight; and the largest virion protein, protein P. The nucleocapsid protein was found to be distributed approximately equally between the nucleoplasmic and nucleolar fractions, whereas most of the other virus-specific proteins were associated with the nucleolar fraction. In the nucleoplasm, most, if not all, of the nucleocapsid protein was in the form of viral ribonucleoproteins.In addition to being in the nucleus, NS₁ has been found concentrated in cytoplasmic fractions containing polyribosomes and ribosomes (Pons, 1972; Compans, 1973). This suggested that NS₁ might be associated with ribosomes as a structural ribosomal protein and that, therefore, NS₁ was in the nucleolus for the purpose of being incorporated into newly assembled ribosomal subunits. Our studies show that in cytoplasmic extracts of infected cells, NS₁ was actually associated with ribosomes, but not as a structural protein; it was simply adsorbed to both the large and the small ribosomal subunits by salt-dissociable bonds. Consequently, NS₁ in the nucleolus is not serving as precursor to a ribosomal structural protein.     

Artificially controlled aggregation of proteins and targeting in hematopoietic cells

The targeting mechanisms for granule proteins in hematopoietic cells are largely unknown. Aggregation is believed to be important for protein sorting-for-entry and sorting-by-retention in endocrine and neuroendocrine cells. We asked whether artificially induced multimerization/aggregation of chimeric proteins could affect their sorting in hematopoietic cells. A system was used that permits ligand-controlled intracellular oligomerization of hybrid proteins containing the FK506-binding protein (FKBP). The hybrid proteins ELA-(FKBP)3 with neutrophil elastase (ELA) and (FKBP*)4-FCS-hGH with a furin cleavage site (FCS) and human growth hormone (hGH) were expressed in the myeloblastic 32D and the rat basophilic leukemia (RBL-1) hematopoietic cell lines. ELA alone is normally targeted to secretory lysosomes. However, the hybrid proteins and ligand-induced aggregates of them were constitutively secreted and not targeted. The hGH that was released at the FCS in (FKBP*)4-FCS-hGH was also constitutively secreted. We conclude that protein multimerization/aggregation per se is not enough to facilitate sorting-for-entry to secretory lysosomes in hematopoietic cells and that improperly folded proteins may be eliminated from sorting by constitutive secretion.     

Single nucleotide polymorphisms of TRAF2 and TRAF5 gene in ankylosing spondylitis: a case–control study

Clinical and Experimental Medicine - Objective To investigate the role of eight locus polymorphisms of tumor necrosis factor receptor-associated factor 2 (TRAF2) and TRAF5 gene and their...     

TRAF2 differentially regulates the canonical and noncanonical pathways of NF-kappaB activation in mature B cells

To examine the role of the TNF-R superfamily signaling protein TRAF2 in mature B cell development and NF-kappaB activation, conditionally TRAF2-deficient mice were produced. B cells lacking TRAF2 expression in these mice possessed a selective survival advantage, accumulated in the lymph nodes and splenic marginal zone, were larger in size, and expressed increased levels of CD21/35. These TRAF2-deficient B cells could not proliferate or activate the canonical NF-kappaB pathway in response to CD40 ligation. By contrast, noncanonical NF-kappaB activation was constitutively hyperactive, with TRAF2-deficient B cells exhibiting close to maximal processing of NF-kappaB2 from p100 to p52 and high levels of constitutive p52 and RelB DNA binding activity. These findings establish TRAF2 as a multifunctional regulator of NF-kappaB activation that mediates activation of the canonical pathway but acts as a negative regulator of the noncanonical pathway. This dual functionality explains the contrasting roles of TRAF2 in B cell maturation and activation.     

TRAF2在B淋巴细胞AP-1信号传导系统中的作用

目的利用人B细胞株模型探讨TRAF2在调控AP-1信号系统中的作用。方法将融合有黄色荧光素(YFP)的野生型(WT-TRAF2)或功能缺失型(DN-TRAF2)TRAF2质粒,以及小干扰RNA-TRAF2质粒转染至人类B淋巴细胞株,过夜培养后经流式细胞仪或抗生素G418筛选阳性转染细胞,通过Western blot、ELISA等方法研究TRAF2对AP-1通路中ERK、JNK、P38磷酸化和AP-1亚单位的细胞核内转移等的影响。结果B细胞过度表达WT-TRAF2可增加ERK和P38的磷酸化水平以及C-FOS的核内转录,而过度表达DN-TRAF2或转染小干扰RNA-TRAF2则减少ERK和P38的磷酸化水平以及C-FOS的核内转录。结论TRAF2可选择性地作用于人B淋巴细胞AP-1信号传导系统中的部分激酶,对B细胞AP-1信号系统的活化有重要作用。     

TRAF2 and TRAF3 signal adapters act cooperatively to control the maturation and survival signals delivered to B cells by the BAFF receptor

Tumor necrosis factor receptor-associated factors 2 and 3 (TRAF2 and TRAF3) were shown to function in a cooperative and nonredundant manner to suppress nuclear factor-kappaB2 (NF-kappaB2) activation, gene expression, and survival in mature B cells. In the absence of this suppressive activity, B cells developed independently of the obligatory B cell survival factor, BAFF (B cell-activating factor of the tumor necrosis factor family). However, deletion of either TRAF2 or TRAF3 from the T cell lineage did not promote T cell survival, despite causing extensive NF-kappaB2 activation. This constitutive, lineage-specific suppression of B cell survival by TRAF2 and TRAF3 determines the requirement for BAFF to sustain B cell development in vivo. Binding of BAFF to BAFF receptor reversed TRAF2-TRAF3-mediated suppression of B cell survival by triggering the depletion of TRAF3 protein. This process was TRAF2 dependent, revealing dual roles for TRAF2 in regulating B cell homeostasis.     

构架蛋白TRAF对CD154诱导转录因子NF-κB活化的影响

目的　研究构架蛋白TRAF1-6在CD154诱导NF-κB活化信号通路中的作用机制。方法通过流式细胞仪分析TRAF蛋白在Ramos B细胞中的基础表达,转染野生型或显性失活TRAF判断TRAF对NF-κB活化的影响,并研究CD154刺激可诱导哪些TRAF蛋白与CD40免疫共沉淀。结果TRAF1、2、3、5和TRAF6在Ramos B细胞中均有基础表达,转染野生型TRAF6较其他TRAF可更显著诱导NF-κB活化,而转染显性失活质粒对CD154诱导NF-κB活化的抑制作用TRAF6>TRAF5>TRAF2> TRAF3。CD154刺激诱导TRAF2、6与CD40共沉淀。结论TRAF6在CD154诱导NF-κB活化中作用最重要;CD154刺激诱导TRAF2、6与CD40形成免疫复合物。     

Caspase-mediated cleavage of TRAF3 in FasL-stimulated Jurkat-T cells

The tumor necrosis factor receptor (TNFR)-associated factor (TRAF) proteins play a central role in the early steps of signal transduction by TNFR superfamily proteins, which induce various cellular responses, including apoptosis. Influences of TRAF proteins on the regulation of cell death and physical interactions between TRAFs and caspases have been reported. In this study, we demonstrate that TRAF3 is proteolyzed during cell death in a caspase-dependent manner. TRAF3 was found to be cleaved by incubation with caspase3 in vitro and by Fas- or CD3-triggering in Jurkat-T cells. The Fas- or CD3-induced cleavage of TRAF3 was blocked by caspase inhibitors and by introduction of alanine substitutions for D347 and D367 residues. Furthermore, the amino-terminal fragment of TRAF3 showed a different intracellular localization from the full-length TRAF3 with preferential distribution to particulate fractions and the nucleus. These findings suggest that TRAF3 may be regulated by caspases during apoptosis of T cells.     

Roles of tumor necrosis factor receptor associated factor 3 (TRAF3) and TRAF5 in immune cell functions

A large and diverse group of receptors utilizes the family of cytoplasmic signaling proteins known as tumor necrosis factor receptor (TNFR)-associated factors (TRAFs). In recent years, there has been a resurgence of interest and exploration of the roles played by TRAF3 and TRAF5 in cellular regulation, particularly in cells of the immune system, the cell types of focus in this review. This work has revealed that TRAF3 and TRAF5 can play diverse roles for different receptors even in the same cell type, as well as distinct roles in different cell types. Evidence indicates that TRAF3 and TRAF5 play important roles beyond the TNFR-superfamily (SF) and viral mimics of its members, mediating certain innate immune receptor and cytokine receptor signals, and most recently, signals delivered by the T-cell receptor (TCR) signaling complex. Additionally, much research has demonstrated the importance of TRAF3-mediated cellular regulation via its cytoplasmic interactions with additional signaling proteins. In particular, we discuss below evidence for the participation by TRAF3 in a number of the regulatory post-translational modifications involving ubiquitin that are important in various signaling pathways.     

MicroRNA-146b-5p suppresses cholangiocarcinoma cells by targeting TRAF6 and modulating p53 translocation

BackgroundIn view of the poor prognosis and high mortality of cholangiocarcinoma, there is a need for new therapeutic strategies. This study aims to reveal the biological function of miR-146b-5p in cholangiocarcinoma cell and its possible mechanism.MethodsThe expression level and prognostic information on miR-146b-5p in cholangiocarcinoma were obtained in TCGA database. The biological function of miR-146b-5p on proliferation and vitality of cholangiocarcinoma cell HUCCT-1 was examined by EdU and MTT assay, and the apoptosis of HUCCT-1 cells transfected with miR-146b-5p mimic, mimic control, inhibitor, inhibitor control was detected by flow cytometry analysis. The western blot was done to evaluate the effect of miR-146b-5p targeting substrate and the expression of p53 in whole-cell protein and mitochondria fractions.ResultsOur finding revealed that miR-146b-5p expression in patients with CHOL was lower than the normal group(p＜0.001). MiR-146b-5p expression was down-regulated in human cholangiocarcinoma HUCCT-1 and RBE cells compared to normal control HIBEC and other cancer cells. The miR-146b-5p mimic could inhibit HUCCT-1 cell proliferation (p＜0.05) and promote HUCCT-1 cell apoptosis significantly (p＜0.05). The results of western blot showed that miR-146b-5p mimic could directly target TRAF6 3′UTR region and up-regulate the expression of p53 in mitochondria and miR-146b-5p inhibitor could down-regulated the level of p53 in mitochondria.ConclusionMiR-146b-5p is a cholangiocarcinoma suppressor by inhibiting cell proliferation and promoting cell apoptosis with targeting TRAF6, possibly via modulating p53 translocation to mitochondria.     

Cytoplasmic Ca2+ gradients evoked by acetylcholine and peptides in pancreatic acinar cells of the guinea-pig

 Cytoplasmic Ca²⁺ levels ([Ca²⁺]_i) in guinea-pig pancreatic acinar cells stimulated with acetylcholine (ACh) as well as cholecystokinin octapeptide (CCK-8), its analogue CCK-JMV-180, bombesin and substance P (SP) have been compared by confocal Ca²⁺ imaging. We found that at intermediate and high concentrations all agonists evoked [Ca²⁺]_i waves emanating from the secretory pole of the cell. The [Ca²⁺]_i gradients evoked by ACh and SP were often unidirectional whereas CCK-8- and bombesin-elicited [Ca²⁺]_i responses consisting of [Ca²⁺]_i waves were normally followed by a secondary phase with reversed [Ca²⁺]_i gradients. At low agonist concentrations the [Ca²⁺]_i responses appeared diffuse or localized to the granular part of the cells. The lag times to the [Ca²⁺]_i rises were shorter in response to ACh and SP than for other peptides. Thus, we found that agonists induced different spatio-temporal patterns of Ca²⁺ waves in pancreatic acinar cells of the guinea-pig. The reactions evoked by SP and bombesin resembled those evoked by ACh and CCK-8, respectively. Received: 29 August 1996 / Received after revision and accepted: 18 October 1996     

Vascular endothelial growth factor (VEGF) is expressed by neoplastic Hodgkin-Reed-Sternberg cells in Hodgkin's disease

Vascular endothelial growth factor (VEGF) is involved in tumour angiogenesis, an important process for the growth and metastatic potential of solid tumours. Numerous studies have demonstrated up-regulation of VEGF at both mRNA and protein level in various tumours and a correlation with advanced stage and prognosis has been demonstrated in some cases. Limited information exists about its role in lymphoid malignancies and in particular, Hodgkin's disease. The present study examined the immunohistochemical expression of VEGF using the monoclonal antibody VG1 in a series of 61 cases of Hodgkin's disease, including both classical Hodgkin's disease and the nodular lymphocyte predominance variant, and correlated these results with microvessel density, using an anti-CD31 monoclonal antibody. In 41 cases (70.6%) of classical Hodgkin's disease and one of the three cases of nodular lymphocyte predominance Hodgkin's disease, the neoplastic Reed-Sternberg and Hodgkin cells expressed VEGF. The staining observed was cytoplasmic, either diffuse or with a focal paranuclear distribution. Macrophages were always positive, while reactive lymphocytes showed occasional positivity. A variable amount of strong extracellular staining was also observed in the tissue stroma and intravascular plasma staining was prominent. There was no statistically significant relationship between VEGF expression and the subtype of Hodgkin's disease or microvessel density. In vitro studies using the Reed-Sternberg cell lines L428 and KM-H2 were also performed in both normoxia and hypoxia and VEGF protein production was assessed by flow cytometry (FACS), immunoassay of cell culture supernatant, and RT-PCR. Analysis by FACS demonstrated a subset of cells in both cell lines reacting with VG1 and analysis of secreted VEGF (pg/ml per 1x10(6) cells) in cell culture supernatant confirmed the normoxic production in both cell lines and significant hypoxic induction (p<0.005). Additionally, both cell lines expressed VEGF mRNA, as demonstrated using the RT-PCR method. In conclusion, neoplastic cells express VEGF in Hodgkin's disease, as is the case in solid tumours, and this expression may be induced by hypoxia. The presence of VEGF in reactive macrophages and in the extracellular matrix might facilitate tumour progression.     

蓝舌病毒两外壳蛋白VP2和VP5在昆虫细胞中的表达 …

目的 研究蓝舌病毒（ＢＴＶ）ＶＰ２与ＶＰ５的免疫学特性,为ＢＴＶ基因工程疫苗研究和病毒样颗粒装配打下基础。方法 将ＢＴＶ１０ ＶＰ２和ＶＰ５基因分别插入杆状病毒表达载体ｐＦａｓｔＢａｃ１,转染昆虫细胞获得重组杆状病毒。用ＳＤＳ－ＰＡＧＥ和Ｗｅｓｔｅｒｎ ｂｌｏｔ检测重组杆状病毒对ＶＰ２和ＶＰ５的表达,运用组织培养中和试验和直接血凝试验检测表达产物的生物学活性。     

Nonredundant and complementary functions of TRAF2 and TRAF3 in a ubiquitination cascade that activates NIK-dependent alternative NF-kappaB signaling

The adaptor and signaling proteins TRAF2, TRAF3, cIAP1 and cIAP2 may inhibit alternative nuclear factor-kappaB (NF-kappaB) signaling in resting cells by targeting NF-kappaB-inducing kinase (NIK) for ubiquitin-dependent degradation, thus preventing processing of the NF-kappaB2 precursor protein p100 to release p52. However, the respective functions of TRAF2 and TRAF3 in NIK degradation and activation of alternative NF-kappaB signaling have remained elusive. We now show that CD40 or BAFF receptor activation result in TRAF3 degradation in a cIAP1-cIAP2- and TRAF2-dependent way owing to enhanced cIAP1, cIAP2 TRAF3-directed ubiquitin ligase activity. Receptor-induced activation of cIAP1 and cIAP2 correlated with their K63-linked ubiquitination by TRAF2. Degradation of TRAF3 prevented association of NIK with the cIAP1-cIAP2-TRAF2 ubiquitin ligase complex, which resulted in NIK stabilization and NF-kappaB2-p100 processing. Constitutive activation of this pathway causes perinatal lethality and lymphoid defects.