The Amino Acid Region 248–382 of the Epstein–Barr Virus Nuclear Protein 2 (EBNA2) is Responsible for the EBNA2-Induced EBV Reactivation

We showed previously that Epstein–Barr virus (EBV) latency is disrupted and the virus-replicative cycle is activated after expression of EBNA2 in the Burkitt's lymphoma-derived Akata cells. Here, an EBNA2 deletion mutant lacking the amino acid residues 248–382, including the region responsible for association with RBP-J , was generated and tested for its ability to activate EBV replication in Akata cells. This mutant was shown clearly deficient in inducing the EBV-replicative cycle, suggesting that association with RBP-J is necessary for the EBV activating function of EBNA2. It is thus likely that EBV activation by EBNA2, seemingly in conflict with its involvement in lymphocyte immortalization, is nevertheless based on the standard mechanism of transactivation by the protein.     

BAMHI DNA Fragment H-Polymorphism of Epstein–Barr Virus is Associated with the Mutations Present in an 89 BP Sequence Localized in EBNA2 Gene

To characterize the genotypes of Epstein-Barr virus (EBV) isolate present in North Africa, viruses were isolated from B-lymphoblastoid cell lines established from the saliva of both Algerian Nasopharyngeal Carcinoma (NPC) patients and EBV-positive normal individuals, Algerian Burkitt's lymphoma cell lines, and NPC biopsies. By nucleotide sequence analysis, we showed that there were two specific missense mutations in an 89 bp region of EBNA2 gene at position 49390-49479 of the EBV genome: a mutation at 49449 (C-->A) and another mutation at 49444 (T-->C), changing their amino acid sequence. The first mutation was found in all B cell lines established from the saliva and 50% of BL cell lines, as well as the W91 cell line, while the second mutation was found in EBV isolates from NPC biopsies, BL cell lines and the M-ABA isolate. A PCR-RFLP analysis on the BamHI DNA fragment H showed that the Hl-H2-polymorphism was specifically associated with M-ABA-like mutation, while H-polymorphism was linked with W91-like mutation. The latter was not identified in NPC biopsies, but was found rather in saliva from NPC patients, normal individuals and BL cell lines. The M-ABA-like mutation, on the other hand, was found in 100% of NPC biopsies and some BL cell lines. This suggests that EBV with H1-H2-polymorphism is tightly implicated in NPC development in North Africa rather than EBV with H-polymorphism.     

EB病毒基因LMP1和EBNA2对支气管上皮细胞的转化

目的 观察Ｅｐｓｔｅｉｎ－Ｂａｒｒ病毒（ＥＢＶ）对支气管上皮细胞的转化作用。方法 用ＥＢＮＡ２和ＬＭＰＩ的真核表达质粒同时转染永生化人胚支气管上皮细胞系ＴＲ,经潮霉素Ｂ筛选得到稳定转化细胞ＴＲ／ＬＭＰＩ－ＥＢＮＡ２。结果 原位杂效和Ｗｅｓｔｅｍ ｂｌｏｔ证实ＴＲ／ＬＭＰＩ－ＥＢＮＡ２有ＥＢＮＡ２和ＬＭＰＩ的ｍＲＮＡ和蛋白表达。生长曲线,ＭＴＴ显示细胞增殖能力增强,软琼脂集落形成率ＴＲ／ＬＭＰＩ－Ｅ     

α2-Antiplasmin Is Associated with the Progression of Fibrosis

Systemic sclerosis results in tissue fibrosis due to the activation of fibroblasts and the ensuing overproduction of the extracellular matrix. We previously reported that the absence of α2-antiplasmin (α2AP) attenuated the process of dermal fibrosis; however, the detailed mechanism of how α2AP affects the progression of fibrosis remained unclear. The goal of the present study was to examine the role of α2AP in fibrotic change. We observed significantly higher levels of α2AP expression in the skin of bleomycin-injected systemic sclerosis model mice in comparison with the levels seen in control mice. We also demonstrated that α2AP induced myofibroblast differentiation, and the absence of α2AP attenuated the induction of myofibroblast differentiation. Moreover, we found that connective tissue growth factor induced the expression of α2AP through both the extracellular signal-regulated kinase 1/2 (ERK1/2) and c-Jun N-terminal kinase (JNK) pathways in fibroblasts. Interestingly, α2AP also induced transforming growth factor-β expression through the same pathways, and the inhibition of ERK1/2 and JNK slowed the progression of bleomycin-induced fibrosis. Our findings suggest that α2AP is associated with the progression of fibrosis, and regulation of α2AP expression by the ERK1/2 and JNK pathways may be an effective antifibrotic therapy for the treatment of systemic sclerosis.Systemic sclerosis (SSc) affects the skin and the internal organs, resulting in tissue fibrosis. Although the disease process involves immunological mechanisms, vascular damage, and activation of fibroblasts, the pathogenesis of SSc remains to be further elucidated. Fibrotic diseases are characterized by excessive scarring due to excessive production, deposition, and contraction of the extracellular matrix (ECM). This process usually occurs over many months and years, and can lead to organ dysfunction or death. Connective tissue growth factor (CTGF) is constitutively overexpressed in fibrotic lesions such as in scleroderma,¹ liver,² renal,^3,4 lung,⁵ and pancreatic fibrosis.⁵ CTGF acts as a downstream effecter of at least some of the profibrotic effects of transforming growth factor-β (TGF-ß),⁶ and promotes fibroblast proliferation, myofibroblasts differentiation, matrix production, and granulation tissue formation.^7,8Human and murine α2-antiplasmin (α2AP) are serpins (serine protease inhibitors) with a molecular weight of 65 to 70 kd,⁹ which rapidly inactivate plasmin, resulting in the formation of a stable inactive complex, plasmin-α2AP.¹⁰ Tissue fibrosis is generally considered to arise due to a failure of the normal wound healing response to terminate.¹¹ Previous our studies show that α2AP is associated with the wound healing and the fibrosis.^12,13 In addition, it has been reported that the level of plasmin-α2AP complex in plasma is elevated in SSc patients.¹⁴ These findings suggest that α2AP may be associated with the progression of fibrotic disease, but the physiological roles of α2AP are not precisely understood. We herein report that α2AP plays an important role in the progression of fibrosis.     

Does the dual-specificity MAPK phosphatase Pyst2-L lead a monogamous relationship with the Erk2 protein?

The dual-specificity phosphatase Pyst2-L was found to be highly expressed in leukocytes derived from AML and ALL patients as well as in certain other solid tumors and lymphoblastoid cell lines. Recently, by use of the 5'-RNA ligation-mediated rapid amplification of cDNA ends (5'-RLM-RACE) technique, we sequenced and cloned the entire open reading frame (ORF) of Pyst2-L. In the present study we determined the effect of exogenous overexpression on Erk1/2 phosphorylation. It was demonstrated that overexpression of this phosphatase in HEK293 cells reduced the basal levels of phospho-Erk1/2 as compared to the same cells transfected with the wild-type vector. This reduction was concomitant with a growth retardation of the Pyst2-L-transfected cells. Treating Pyst2-L transfected cells with known activators of the MAPK signaling cascade such as TPA or stimulating them by serum, it was demonstrated that the up regulation of phospho-Erk1/2, caused by these activators, was only partially suppressed by the over expression of the Pyst2-L phosphatase in these cells. These results together with our previous ones showing that the TPA-induced up regulation of Pyst2-L mRNA was only partially inhibited by the use of a specific Mek1/2 inhibitor, lead us to ask whether the Pyst2-L phosphatase has a monogamous relationship with the Erk2 protein. To answer this question, we employed the pull-down method and showed that in addition to phospho-Erk1/2, recombinant Pyst2-L binds the phospho-JNK protein. These findings may raise new perspectives regarding the role played by this phosphatase in malignant cells and in activation processes.     

Epstein－Barr病毒核抗原Ⅱ（EBNA2）基因免疫的初步研究

利用基因免疫技术，将重组质粒ＰＳＧ５－ＥＢＮＡ２注入Ｂａｌｂ／Ｃ小鼠肌肉中，于第２、４、８周检测鼠血清中抗－ＥＢ病毒核蛋白抗原Ⅱ的特异抗体，结果表明，８３％（５／６）的免疫小鼠产生特异抗体，且抗体滴度随时间变化增高。     

Eostein—Barr病毒核抗原Ⅱ（EBNA2）基因免疫的初…

利用基因免疫技术，将重组质粒ｐＳＧ５－ＥＢＮＡ２注入Ｂａｌｂ／Ｃ小鼠肌肉中，于第２、４、８周检测鼠血清中抗－ＥＢ病毒核蛋白抗原Ⅱ的特异抗体，结果表明，８３％的免疫小鼠产生特异抗体，且抗体滴度随时间变化增高。     

EBNA1在鼻咽癌发生中细胞免疫应答的研究

EB病毒核心抗原1（EB nuclear antigen1,EBNA1）是唯一一个在EB病毒（Epstein-Barr Virus,EBV）潜伏感染和活化状态中均表达的抗原,也是在鼻咽癌（Nasopharyngealcarcinoma,NPC）组织中表达的几个EB病毒抗原之一.早期研究显示EBNA1为DNA结合蛋白,在促进细胞转化、EBV基因组稳定、复制、基因的表达方面起着重要的作用,并可以诱导体液免疫应答.近来研究表明在EBNAI的C末端含有CD4＋T细胞表位,在诱导细胞免疫应答方面起着重要作用,鉴此,本文对EBNA1在NPC发生中细胞免疫应答方面的研究做一综述.     

"Go with the flow": how Krüppel-like factor 2 regulates the vasoprotective effects of shear stress

Laminar shear stress is known to confer potent anti-inflammatory, antithrombotic, and antiadhesive effects by differentially regulating endothelial gene expression. The identification of Krüppel-like factor 2 as a flow-responsive molecule has greatly advanced our understanding of molecular mechanisms governing vascular homeostasis. This review summarizes the current understanding of Krüppel-like factor 2 action in endothelial gene expression and function.     

Serum IgG2 Concentration Is Associated with Gm-Allotypes of IgG2 But Not with the R131H Polymorphism of Human Fcγ Receptor Type IIa

Serum concentrations of immunoglobulins IgG, IgG1, and IgG2 were determined in 62 Finnish subjects who were also typed for Gm(n) allele of IgG2 and R131 and H131 alleles of the Fc receptor IIa. Statistically significant G2m-allotype-associated differences in serum concentrations of IgG2 were found; the mean concentration of IgG2 was high in Gm(n)-positive homozygotes (3.9 g/liter) and low in Gm(n)-negative individuals (2.6 g/liter; P = 0.0036), which is in accordance with previous reports. Contrary to an earlier report, no statistically significant R131/H131-allotype-associated differences were found in serum concentrations of IgG2, not even in the case where the IgG2 concentration was calculated relative to the IgG1 or IgG concentration (IgG2/IgG1 or IgG2/IgG). The gene frequencies of R131 and H131 alleles were 0.516 and 0.484, respectively, which did not differ significantly from those reported earlier for Finnish or other Caucasian populations.     

The properties of the Kir6.1–6.2 tandem channel co-expressed with SUR2A

Functional ATP-sensitive K (KATP) channels have an octameric subunit structure with four pore-forming subunits (Kir6.x) and four sulfonylurea receptors (SURx). In the present study, the properties of the heteromeric KATP channel whose pore subunits are composed of Kir6.1 and Kir6.2 were examined using a heterologous expression system. In COS7 cells co-transfected with Kir6.1, Kir6.2 and SUR2A at a ratio of 1:1:2, KATP channels showed various unitary conductances between those of Kir6.1/SUR2A (33.6+/-4.2 pS) and Kir6.2/ SUR2A (67.1+/-1.6 pS). Kir6.1-6.2 tandem protein, constructed by fusing the C-terminus of Kir6.1 to the N-terminus of Kir6.2 with a ten glutamine linker sequence, also formed a channel with an intermediate conductance (58.9+/-1.5 pS). Kir6.2 and Kir6.1-6.2 showed similar sensitivity to ATP4-: half-maximal inhibition (IC50) was obtained at 14.1+/-12.8 microM and 17.6+/-9.6 microM, respectively. In the presence of Mg2+, Kir6. 1-6.2 was significantly less sensitive than Kir6.2 to MgATP (IC50=95.5+/-49.6 microM versus 18.9+/-5.0 microM). These results suggest that Kir6.1 and Kir6.2 are endowed with the potential to form a heteromeric KATP channel, which has a low sensitivity to MgATP.     

Association of HYPA haplotype in the mannose-binding lectin gene-2 with Behçet's disease

Behcet's disease (BD) is a multisystemic, recurrent inflammatory disease caused by the combinations of multiple genetic and environmental factors. Moreover, the MBL2 gene single-nucleotide polymorphisms and haplotypes are known to increase the susceptibility to inflammatory disease and to alter the serum levels of mannose-binding lectin (MBL. We postulated that the haplotypes of the MBL2 gene influence therapeutic response in BD, thus affecting the clinical symptoms in 282 BD patients. The promoter region, MBL2-550*C/*C (L/L) homozygote was found to have a lower frequency in BD patients than that in controls. No difference was observed in the allele frequencies of G-221C (Y/X), C+4T (P/Q) or Gly54Asp (A/B) of the MBL2 gene in BD patients and in controls. The HYPA haplotype contributed to BD occurrence, whereas the LYPA haplotype was negatively associated with BD. BD patients with several symptoms and with an earlier disease-onset age had a higher HYPA haplotype frequency. BD patients showing poor response (S) to therapy had a higher HYPA frequency than those showing good response (M). It seems that possessing HYPA increases the risk of BD and that the MBL2 HYPA haplotype plays a role in MBL levels and increases the susceptibility to BD.     

Can the pentitol-hexitol theory explain the clinical observations made with xylitol?

The natural dietary carbohydrate xylitol has been used as a source of energy in infusion therapy and found to act curatively in certain clinical situations. Xylitol has also been used as a sweetener in the diabetic diet and as a non- or anticariogenic agent. Xylitol is a sugar alcohol (polyhydric alcohol) of the pentitol type. The various advantageous clinical effects associated with enteral and parenteral administration of xylitol can be considered to result from the five-carbon (pentitol) nature of the molecule and from the molecule's special configuration even when compared with other pentitols. Such effects may be regarded as simple consequences of evolutionary expediency in a situation where human nutrition and man's significant energy-yielding metabolic pathways are associated with the six-carbon nature of D-glucose and the close derivatives and polymers of D-glucose and related sugars, and the physiologic involvement of the five-carbon xylitol in several ancillary pathways. Consequently, most clinical effects occasioned by xylitol cannot be expected to be caused by six-carbon hexitols such as D-mannitol and D-glucitol. A simple pentitol-hexitol theory seems to explain most of the clinical effects associated with the administration of xylitol. This theory is in congruence with the general evolutionary development in which the metabolism of C(6)-based carbohydrates is often inhibited by C(5)-based ones (as manifested in certain bacterial infections in man), or where the presence of the C(5)-based xylitol forwards therapeutically significant metabolic pathways (as observed in parenteral nutrition and treatment of certain enzyme deficiencies). The validity of the theory can be verified in controlled clinical trials.     

Is the alpha-2A adrenergic receptor gene (ADRA2A) associated with attention-deficit/hyperactivity disorder?

Attention-Deficit/Hyperactivity Disorder (ADHD) is a complex childhood-onset psychiatric disorder characterized by marked symptoms of inattention, hyperactivity, and impulsivity. The role of genetic factors in its etiology is strongly supported by family, adoption, and twin studies. Although most of the molecular studies have investigated the dopamine D4 receptor gene (DRD4) and the dopamine transporter gene (DAT1) genes in its etiology, pharmacological and brain imaging evidences seem to indicate that genes of the adrenergic system could also be attractive for association studies. We investigated a sample of 96 Brazilian ADHD children and adolescents and their parents for the ADRA2A MspI polymorphism. Although no association with either MspI allele was observed through the haplotype relative risk (HRR) analysis, effects of the ADRA2A gene on inattention and combined (inattention + hyperactivity/impulsivity) symptom scores were detected (U = 222.5, z = 2.19, P = 0.03; and U = 208.5, z = 2.32, P = 0.02, respectively). Our results suggest that the ADRA2A gene might have a small effect on ADHD susceptibility or that this gene might modulate the severity of the disorder. They are also consistent with the noradrenergic theories of ADHD, suggesting a role for the alpha2A adrenergic receptors in the disorder.