Stress downregulates hippocampal expression of the adhesion molecules NCAM and CHL1 in mice by mechanisms independent of DNA methylation of their promoters

Stress is an important physiological regulator of brain function in young and adult mammals. The mechanisms underlying regulation of the consequences of stress, and in particular severe chronic stress, are thus important to investigate. These consequences most likely involve changes in synaptic function of brain areas being part of neural networks that regulate responses to stress. Cell adhesion molecules have been shown to regulate synaptic function in the adult and we were thus interested to investigate a regulatory mechanism that could influence expression of three adhesion molecules of the immunoglobulin superfamily (NCAM, L1 and CHL1) after exposure of early postnatal and adult mice to repeated stress. We hypothesized that reduction of adhesion molecule expression after chronic stress, as observed previously in vivo, could be due to gene silencing of the three molecules by DNA methylation. Although adhesion molecule expression was reduced after exposure of C57BL/6 mice to stress, thus validating our stress paradigm as imposing changes in adhesion molecule expression, we did not observe differences in methylation of CpG islands in the promoter regions of NCAM, L1 and CHL1, nor in the promoter region of the glucocorticoid receptor in the hippocampus, the expression of which at the protein level was also reduced after stress. We must therefore infer that severe stress in mice of the C57BL/6 strain downregulates adhesion molecule levels by mechanisms that do not relate to DNA methylation.Key words: stress, immunoglobulin superfamily, adhesion molecules, promoter, DNA methylation, hippocampus, glucocorticoid receptor     

Epigenetic DNA methylation in the promoters of the Igf1 receptor and insulin receptor genes in db/db mice

We have investigated promoter methylation of the Insr, Igf1 and Igf1r genes in skeletal and cardiac muscles of normal and diabetic db/db mice. No differences in Insr promoter methylation were found in the heart and skeletal muscles and no methylation was detected in the Igf1 promoter in skeletal muscle. In skeletal muscle, db/db males exhibited a 7.4-fold increase in Igf1r promoter methylation, which was accompanied by a 1.8-fold decrease in Igf1r mRNA levels, compared with controls. More than 50% of the detected methylation events were concentrated within an 18 bp sequence that includes one of the Sp1 binding sites. We conclude that the methylation level and pattern of the Igf1r promoter in skeletal muscle is related to gender and the diabetic state.     

Pin1促进肿瘤发展相关机制的研究进展

脯氨酰顺反异构酶1(peptidyl-prolyl cis-trans isomerase NIMA-interacting 1,Pin1)为细胞内主要起信号传导作用的小分子蛋白。Pin1在肿瘤中的异常表达和信号调控促进肿瘤的发展,包括诱导耐药、辅助致肿瘤性病毒感染、参与肿瘤的缺氧代谢和其它信号调控等。本文对于Pin1的促肿瘤发展特点进行简要总结。     

细菌感染对家蚕DNA甲基化与组蛋白乙酰化相关基因表达的影响

【目的】探讨DNA甲基化及组蛋白乙酰化是否参与家蚕 Bombyx mori 免疫反应的调控。【方法】对家蚕与其他生物的DNA甲基转移酶 (DNMT)、组蛋白去乙酰化酶（HDAC）与组蛋白乙酰转移酶（HAT）的蛋白序列进行系统进化分析;利用定量PCR检测家蚕5龄第3天幼虫感染病原菌绿脓杆菌 Pseudomonas aeruginosa 和金黄色葡萄球菌 Staphylococcus aureus 后 BmDNMT 1, BmHDACI-1, BmHDACI-2和 BmHAT 1在家蚕脂肪体组织中的表达变化;给家蚕5龄第2天幼虫注射DNMT, HDAC和HAT抑制剂,观察它们对家蚕感染细菌后的存活率的影响。【结果】系统进化分析显示,BmDNMT1在进化上呈现特殊性,独立于其他昆虫DNMT1的进化,而BmHDACs和BmHAT在进化上相对保守。定量PCR检测表明,在两种细菌感染后,BmDNMT1, BmHDACs 和 BmHAT1 在家蚕幼虫脂肪体中的表达水平均有不同程度的上升。然而,DNMT, HDAC和HAT抑制剂对家蚕幼虫感染细菌后的存活率并无明显影响。【结论】本研究发现感染绿脓杆菌和金黄色葡萄球菌后,家蚕幼虫脂肪体中 BmDNMT1, BmHDACs 和 BmHAT1 的表达水平有不同程度的上调,推测DNA甲基化和组蛋白乙酰化/去乙酰化可能参与家蚕免疫反应的调控。     

Effect of trichloroethylene on DNA methylation and expression of early-intermediate protooncogenes in the liver of B6C3F1 mice.

Trichloroethylene (TCE) is a multimedia environmental pollution that is carcinogenic in mouse liver. The ability of TCE to modulate DNA methylation and the expression of immediate-early protooncogenes was evaluated. Female B6C3F1 mice were administered 1000 mg/kg TCE by gavage 5 days/week and killed after 5, 12, or 33 days of exposure. Methylation of DNA as 5-methylcytosine was decreased by 5 days of treatment with TCE and remained reduced for 33 days. TCE also decreased the methylation of the promoter regions for the protooncogenes, c-jun and c-myc. The expression of the mRNA for the two protooncogenes was increased between 60 and 120 minutes after administering the last dose of TCE and returned to control level by 24 hours. The expression of the mRNA for c-fos remained undetectable after administering TCE. Hence, TCE decreased the methylation both of total DNA and the promoters for the c-jun and c-myc genes and increased the expression of their mRNA. The decreased methylation and increased expression of the two immediate-early protooncogenes might be associated with TCE-induced increase in cell proliferation and promotion of tumors.     

Comparison of influenza outbreaks in the Republic of Kazakhstan and Russia induced by 2009 yearly new variant of A(H1N1) influenza virus

The aim of the work is the comparison of the epidemiology of influenza and acute respiratory virus infections(ARVI)in the Republic of Kazakhstan with the corresponding influenza epidemic in Russia induced by influenza pandemic virus A/California/07/2009 in 2009. Data on influenza and ARVI from the Republic of Kazakhstan and Federal Center of influenza was collected and investigated over the course of several weeks from hospitalized patients with the same diagnosis among all population and in age groups on 16 territories of Kazakhstan and in 49 major cities of Russia. The epidemic in Kazakhstan resembled the Russian epidemic in terms of its abnormally early beginning,expression of monoaetiology,the spread of the epidemic into all territories and start of the epidemics among adult population. High percentage of hospitalized people and lethal outcome were registered in this epidemic. Similarity of epidemic process character in corresponding border-line territories of both countries was found out.     

Segregation of viral double-stranded and single-stranded DNA molecules in nuclei of adenovirus infected cells as revealed by electron microscope in situ hybridization.

Formation of progeny viruses in the nuclei of HeLa cells infected with adenovirus type 5 was studied at the ultrastructural level by in situ hybridization techniques allowing specific detection of either viral double-stranded DNA (dsDNA) or single-stranded DNA (ssDNA). Prior to the initiation of replication of viral genomes, infective DNA molecules which entered the nucleus of the target cell were randomly distributed among host chromatin fibers including nucleolus-associated chromatin. They were double-stranded, that is, without single-strand breaks. Such association of viral DNA with host condensed chromatin also occurred in mitosis. The initiation of viral genome replication occurred simultaneously with the appearance in the nucleoplasm of small fibrillar regions containing intermingled viral dsDNA and ssDNA. Later, at the intermediate stage of nuclear transformation, viral dsDNA and ssDNA molecules were almost entirely separated into two contiguous substructures. At this stage, viruses were observed occasionally in the vicinity of viral ssDNA accumulation sites. Still later, an additional substructure developed in the centre of the nucleus which consisted of large quantities of viral dsDNA, traces of viral ssDNA and abundant viruses. Portions of viral ssDNA were attached to some viruses even at late stage of nuclear transformation, an association which strongly suggests the occurrence of encapsidation of at least some of the viral genomes while they are still engaged in replication.     

Regulation of MMP-3 expression and secretion by the chemokine eotaxin-1 in human chondrocytes

Background  

Osteoarthritis (OA) is characterized by the degradation of articular cartilage, marked by the breakdown of matrix proteins. Studies demonstrated the involvement of chemokines in this process, and some may potentially serve as diagnostic markers and therapeutic targets; however, the underlying signal transductions are not well understood.     

The downregulation of FLOWERING LOCUS C (FLC) expression in plants with low levels of DNA methylation and by vernalization occurs by distinct mechanisms

FLOWERING LOCUS C (FLC), a repressor of flowering, is a major determinant of flowering time in Arabidopsis. FLC expression is repressed by vernalization and in plants with low levels of DNA methylation, resulting in early flowering. This repression is not associated with changes of DNA methylation within the FLC locus in either vernalized plants or plants with low levels of DNA methylation. In both cases, there is a reduction of histone H3 trimethyl-lysine 4 (K4) and acetylation of both histones H3 and H4 around the promoter-translation start of FLC. The expression of the two genes flanking FLC is also repressed in both conditions and repression is associated with decreased histone H3 acetylation. The changes in histone modifications at the FLC gene cluster, which are similar in vernalized plants and in plants with reduced DNA methylation, must arise by different mechanisms. VERNALIZATION 1, VERNALIZATION 2 and VERNALIZATION INSENSITIVE 3 modulate FLC expression in vernalized plants; these proteins play no role in the downregulation of FLC in plants with low levels of DNA methylation. Chimeric FLC::GUS transgenes respond to vernalization but these same transgenes show a position-dependent response to low levels of DNA methylation. In plants with reduced DNA methylation, expression of the five MADS AFFECTING FLOWERING (MAF) genes is repressed, suggesting that DNA methylation alters the expression of a trans-acting regulator common to FLC and members of the related MAF gene family. Our observations suggest that DNA methylation is not part of the vernalization pathway.     

Induction of humoral and cellular immune responses in mice by a recombinant fowlpox virus expressing the E2 protein of bovine viral diarrhea virus

A recombinant fowlpox virus (rFPV/E2) expressing the E2 protein of bovine viral diarrhea virus (BVDV) was constructed and characterized. Mice were immunized with recombinant virus and both humoral and cellular immune responses were studied. rFPV/E2 induced BVDV-specific antibodies which were detected by ELISA. In addition, mouse sera were shown to neutralize BVDV. A cytokine ELISA assay revealed that mice vaccinated with rFPV/E2 induced 7-fold more interferon-gamma than parental fowlpox virus.     

Induction of Th1 type response by DNA vaccinations with N, M, and E genes against SARS-CoV in mice

Vaccination against the SARS-CoV infection is an attractive means to control the spread of viruses in public. In this study, we employed a DNA vaccine technology with the levamisole, our newly discovered chemical adjuvant, to generate Th1 type of response. To avoid the enhancement antibody issue, genes encoding the nucleocapsid, membrane, and envelope protein of SARS-CoV were cloned and their expressions in mammalian cells were determined. After the intramuscular introduction into animals, we observed that the constructs of the E, M, and N genes could induce high levels of specific antibodies, T cell proliferations, IFN-gamma, DTH responses, and in vivo cytotoxic T cells activities specifically against SARS-CoV antigens. The highest immune responses were generated by the construct encoding the nucleocapsid protein. The results suggest that the N, M, and E genes could be used as the targets to prevent SARS-CoV infection in the DNA vaccine development.     

二乙基亚硝胺诱导大鼠肝癌组织CLDN1基因表达及其甲基化

目的探讨二乙基亚硝胺（diethylnitrosamine,DEN）诱导大鼠肝癌发生中肝癌组织CLDN1基因表达及其启动子甲基化的规律。方法65只雄性Wistar大鼠随机选择40只作为模型组,其余作为正常组。模型组在1-12周饮用含DEN80mg／L的饮水以诱癌（每日8mg／kg）,各组在造模过程的第4周、8周、12周、16周随机5只取肝,第20周剩余大鼠取肝,应用RT-PCR方法检测肝组织CLDN1mRNA的表达,应用MSP法检测肝组织CLDN1启动子甲基化和非甲基化。结果模型大鼠病死率为10％（4／40）,正常组无死亡。至第20周,成瘤率达到100％。RT—PCR显示,与正常组比较,模型组在16周和20周CLDN1 mRNA表达下调（P〈0．05）,其他各周两组差异不显著。MSP结果表明,模型组肝组织CLDN1甲基化率达77．78％,而正常肝组织甲基化率为24％,两者比较差异有显著性（P〈0．01）。结论CLDN1启动子甲基化及CLDN1基因表达下调与大鼠肝癌病变相关,对其机制值得进一步深入研究。     

Decreased DMT1 and increased ferroportin 1 expression is the mechanisms of reduced iron retention in macrophages by erythropoietin in rats

Recycled iron from reticuloendothelial macrophages to erythroid precursors is important to maintain the iron homeostasis. However, the molecular mechanisms underlying iron homeostasis in macrophages are poorly understood. In this study, male Sprague-Dawley rats were treated with recombinant human erythropoietin (rHuEpo, 500 IU/day, s.c.) for 3 days. At the fifth day, peritoneal exudate macrophages were harvested, and then (55)Fe uptake and release were measured by liquid scintillation counting method. The expression of divalent metal transporter 1 (DMT1) and ferroportin 1 (FPN1) in peritoneal exudate macrophages was detected by RT-PCR and Western blot. In order to exclude the direct effect of rHuEpo on macrophages, the parallel experiments were performed with incubation normal peritoneal exudate macrophages with rHuEpo (2 IU/ml). Our results showed rHuEpo injection reduced the peritoneal exudate macrophages iron retention. The uptake of Fe(II) was decreased via the suppression of DMT1 (+IRE) expression and the release of Fe(II) was increased with increasing the expression of FPN1 in macrophages. Moreover, the expression of HAMP mRNA was four times lower in rHuEpo-treated liver of rats than control group (CG). HAMP mRNA expression was increased; the synthesis of DMT1 had no significant change, whereas the FPN1 was decreased in normal peritoneal exudate macrophages after treatment with rHuEpo in vitro. We conclude that hepcidin may play a major, causative role in the change of FPN1 synthesis and that decreased the iron retention in macrophages of rHuEpo-treated rats.