Herpes simplex virus ICP27 is required for virus-induced stabilization of the ARE-containing IEX-1 mRNA encoded by the human IER3 gene

Herpes simplex virus (HSV) stifles cellular gene expression during productive infection of permissive cells, thereby diminishing host responses to infection. Host shutoff is achieved largely through the complementary actions of two viral proteins, ICP27 and virion host shutoff (vhs), that inhibit cellular mRNA biogenesis and trigger global mRNA decay, respectively. Although most cellular mRNAs are thus depleted, some instead increase in abundance after infection; perhaps surprisingly, some of these contain AU-rich instability elements (AREs) in their 3'-untranslated regions. ARE-containing mRNAs normally undergo rapid decay; however, their stability can increase in response to signals such as cytokines and virus infection that activate the p38/MK2 mitogen-activated protein kinase (MAPK) pathway. We and others have shown that HSV infection stabilizes the ARE mRNA encoding the stress-inducible IEX-1 mRNA, and a previous report from another laboratory has suggested vhs is responsible for this effect. However, we now report that ICP27 is essential for IEX-1 mRNA stabilization whereas vhs plays little if any role. A recent report has documented that ICP27 activates the p38 MAPK pathway, and we detected a strong correlation between this activity and stabilization of IEX-1 mRNA by using a panel of HSV type 1 (HSV-1) isolates bearing an array of previously characterized ICP27 mutations. Furthermore, IEX-1 mRNA stabilization was abrogated by the p38 inhibitor SB203580. Taken together, these data indicate that the HSV-1 immediate-early protein ICP27 alters turnover of the ARE-containing message IEX-1 by activating p38. As many ARE mRNAs encode proinflammatory cytokines or other immediate-early response proteins, some of which may limit viral replication, it will be of great interest to determine if ICP27 mediates stabilization of many or all ARE-containing mRNAs.     

Gene expression profiles in chondrosarcoma cells subjected to cyclic stretching and hydrostatic pressure. A cDNA array study

Mechanical forces have a profound effect on cartilage tissue and chondrocyte metabolism. Strenuous loading inhibits the cellular metabolism, while optimal level of loading at correct frequency raises an anabolic response in chondrocytes. In this study, we used Atlas Human Cancer cDNA array to investigate mRNA expression profiles in human chondrosarcoma cells stretched 8% for 6 hours at a frequency of 0.5 Hz. In addition, cultures were exposed to continuous and cyclic (0.5 Hz) 5 MPa hydrostatic pressure. Cyclic stretch had a more profound effect on the gene expression profiles than 5 MPa hydrostatic pressure. Several genes involved with the regulation of cell cycle were increased in stretched cells, as well as mRNAs for PDGF-B, glucose-1-phosphate uridylyltransferase, Tiam1, cdc37 homolog, Gem, integrin alpha6, and matrix metalloproteinase-3. Among down-regulated genes were plakoglobin, TGF-alpha, retinoic acid receptor-alpha and Wnt8b. A smaller number of changes was detected after pressure treatments. Plakoglobin was increased under cyclic and continuous 5 MPa hydrostatic pressure, while mitogen-activated protein kinase-9, proliferating cell nuclear antigen, Rad6, CD9 antigen, integrins alphaE and beta8, and vimentin were decreased. Cyclic and continuous pressurization induces a number of specific changes. In conclusion, a different set of genes were affected by three different types of mechanical stimuli applied on chondrosarcoma cells.     

Altered cellular mRNA levels in human cytomegalovirus-infected fibroblasts: viral block to the accumulation of antiviral mRNAs.

The effect of human cytomegalovirus (HCMV) infection on cellular mRNA accumulation was analyzed by gene chip technology. During a 48-h time course after infection of human diploid fibroblasts, 1,425 cellular mRNAs were found to be up-regulated or down-regulated by threefold or greater in at least two consecutive time points. Several classes of genes were prominently affected, including interferon response genes, cell cycle regulators, apoptosis regulators, inflammatory pathway genes, and immune regulators. The number of mRNAs that were up-regulated or down-regulated were roughly equal over the complete time course. However, for the first 8 h after infection, the number of up-regulated mRNAs was significantly less than the number of down-regulated mRNAs. By analyzing the mRNA expression profile of cells infected in the presence of cycloheximide, it was found that a minimum of 25 mRNAs were modulated by HCMV in the absence of protein synthesis. These included mRNAs encoded by a small number of interferon-responsive genes, as well as beta interferon itself. Cellular mRNA levels in cytomegalovirus-infected cells were compared to the levels in cells infected with UV-inactivated virus. The inactivated virus caused the up-regulation of a much greater number of mRNAs, many of which encoded proteins with antiviral roles, such as interferon-responsive genes and proinflammatory cytokines. These data argue that one or more newly synthesized viral gene products block the induction of antiviral pathways that are triggered by HCMV binding and entry.     

Genome-wide transcriptional orchestration of circadian rhythms in Drosophila

Circadian rhythms govern the behavior, physiology, and metabolism of living organisms. Recent studies have revealed the role of several genes in the clock mechanism both in Drosophila and in mammals. To study how gene expression is globally regulated by the clock mechanism, we used a high density oligonucleotide probe array (GeneChip) to profile gene expression patterns in Drosophila under light-dark and constant dark conditions. We found 712 genes showing a daily fluctuation in mRNA levels under light-dark conditions, and among these the expression of 115 genes was still cycling in constant darkness, i.e. under free-running conditions. Unexpectedly the expression of a large number of genes cycled exclusively under constant darkness. We found that cycling in most of these genes was lost in the arrhythmic Clock (Clk) mutant under light-dark conditions. Expression of periodically regulated genes is coordinated locally on chromosomes where small clusters of genes are regulated jointly. Our findings reveal that many genes involved in diverse functions are under circadian control and reveal the complexity of circadian gene expression in Drosophila.     

RASSF6 Expression in Adipocytes Is Down-Regulated by Interaction with Macrophages

Macrophage infiltration into adipose tissue is associated with obesity and the crosstalk between adipocytes and infiltrated macrophages has been investigated as an important pathological phenomenon during adipose tissue inflammation. Here, we sought to identify adipocyte mRNAs that are regulated by interaction with infiltrated macrophages in vivo. An anti-inflammatory vitamin, vitamin B6, suppressed macrophage infiltration into white adipose tissue and altered mRNA expression. We identified >3500 genes whose expression is significantly altered during the development of obesity in db/db mice, and compared them to the adipose tissue mRNA expression profile of mice supplemented with vitamin B6. We identified PTX3 and MMP3 as candidate genes regulated by macrophage infiltration. PTX3 and MMP3 mRNA expression in 3T3-L1 adipocytes was up-regulated by activated RAW264.7 cells and these mRNA levels were positively correlated with macrophage number in adipose tissue in vivo. Next, we screened adipose genes down-regulated by the interaction with macrophages, and isolated RASSF6 (Ras association domain family 6). RASSF6 mRNA in adipocytes was decreased by culture medium conditioned by activated RAW264.7 cells, and RASSF6 mRNA level was negatively correlated with macrophage number in adipose tissue, suggesting that adipocyte RASSF6 mRNA expression is down-regulated by infiltrated macrophages in vivo. Finally, this study also showed that decreased RASSF6 expression up-regulates mRNA expression of several genes, such as CD44 and high mobility group protein HMGA2. These data provide novel insights into the biological significance of interactions between adipocytes and macrophages in adipose tissue during the development of obesity.     

Expression changes in mRNAs and mitochondrial damage in lens epithelial cells with selenite

An overdose of sodium selenite induces cataracts in young rats. The mid-stage events producing the cataract include calpain-induced hydrolysis and precipitation of lens proteins. Apoptosis in lens epithelial cells has been suggested as an initial event in selenite cataracts. Expression levels of two genes associated with apoptosis were altered in lens epithelial cells from selenite-injected rats. The purpose of the present experiment was to perform a more comprehensive search for changes in expression of mRNAs in lens epithelial cells in order to more fully delineate the early events in selenite-induced cataracts. Lens epithelial cells were harvested at 1 and 2 days after a single subcutaneous injection of sodium selenite (30 mumol/kg body weight) into 12-day-old rats. Gene expression was analyzed using a commercial DNA array (Rat Genome U34A GeneChip array, Affymetrix). Of approximately 8000 genes assayed by hybridization, 13 genes were decreased and 27 genes were increased in the rat lens epithelial cells after injection of selenite. Some of the up-regulated genes included apoptosis-related genes, and a majority of the down-regulated genes were mitochondrial genes. Previously observed changes in expression of EGR-1 mRNA were also confirmed. Changes in the expression patterns of mRNAs were also confirmed by RT-PCR. To determine the mechanism for damage of lens epithelial cells (alpha TN4 cell) by culture in selenite, leakage of cytochrome c from mitochondria was measured. Selenite caused significant leakage of cytochrome c into the cytosol of alpha TN4 cells. Our data suggested that the loss of integrity of lens epithelial cells by selenite might be caused by preferential down-regulation of mitochondrial RNAs, release of cytochrome c, and impaired mitochondrial function. Up-regulation of mRNAs involved in maintenance of DNA, regulation of metabolism, and induction of apoptosis may also play roles.     

人呼吸道合胞病毒感染的A549细胞中长链非编码RNA表达谱研究

目的:探讨人呼吸道合胞体病毒(human respiratory syncytial virus,RSV)感染A549细胞的长链非编码RNA(long non-coding RNAs,lncRNA)表达谱的差异,更好地了解宿主与RSV之间的相互作用的可能分子机制.方法:1 MOI RSV感染A549细胞,24h后提取R...