Best5: a novel interferon-inducible gene expressed during bone formation

Unexpected regulatory functions of cyprinid Viperin on inflammation and metabolism

BACKGROUND

Viperin, also known as radical S-adenosyl-methionine domain containing protein 2 (RSAD2), is an interferon-inducible protein that is involved in the innate immune response against a wide array of viruses. In mammals, Viperin exerts its antiviral function through enzymatic conversion of cytidine triphosphate (CTP) into its antiviral analog ddhCTP as well as through interactions with host proteins involved in innate immune signaling and in metabolic pathways exploited by viruses during their life cycle. However, how Viperin modulates the antiviral response in fish remains largely unknown.

RESULTS

For this purpose, we developed a fathead minnow (Pimephales promelas) clonal cell line in which the unique viperin gene has been knocked out by CRISPR/Cas9 genome-editing. In order to decipher the contribution of fish Viperin to the antiviral response and its regulatory role beyond the scope of the innate immune response, we performed a comparative RNA-seq analysis of viperin-/- and wildtype cell lines upon stimulation with recombinant fathead minnow type I interferon.

CONCLUSIONS

Our results revealed that Viperin does not exert positive feedback on the canonical type I IFN but acts as a negative regulator of the inflammatory response by downregulating specific pro-inflammatory genes and upregulating repressors of the NF-κB pathway. It also appeared to play a role in regulating metabolic processes, including one carbon metabolism, bone formation, extracellular matrix organization and cell adhesion.

Network pharmacology combined with GEO database identifying the mechanisms and molecular targets of Polygoni Cuspidati Rhizoma on Peri-implants

Peri-implants is a chronic disease leads to the bone resorption and loss of implants. Polygoni Cuspidati Rhizoma (PCRER), a traditional Chinese herbal has been used to treat diseases of bone metabolism. However, its mechanism of anti-bone absorption still remains unknown. We aimed to identify its molecular target and the mechanism involved in PCRER potential treatment theory to Peri-implants by network pharmacology. The active ingredients of PCRER and potential disease-related targets were retrieved from TCMSP, Swiss Target Prediction, SEA databases and then combined with the Peri-implants disease differential genes obtained in the GEO microarray database. The crossed genes were used to protein–protein interaction (PPI) construction and Gene Ontology (GO) and KEGG enrichment analysis. Using STRING database and Cytoscape plug-in to build protein interaction network and screen the hub genes and verified through molecular docking by AutoDock vina software. A total of 13 active compounds and 90 cross targets of PCRER were selected for analysis. The GO and KEGG enrichment analysis indicated that the anti-Peri-implants targets of PCRER mainly play a role in the response in IL-17 signaling, Calcium signaling pathway, Toll-like receptor signaling pathway, TNF signaling pathway among others. And CytoHubba screened ten hub genes (MMP9, IL6, MPO, IL1B, SELL, IFNG, CXCL8, CXCL2, PTPRC, PECAM1). Finally, the molecular docking results indicated the good binding ability with active compounds and hub genes. PCRER’s core components are expected to be effective drugs to treat Peri-implants by anti-inflammation, promotes bone metabolism. Our study provides new thoughts into the development of natural medicine for the prevention and treatment of Peri-implants.

Viperin Reveals Its True Function

Most cells respond to viral infections by activating innate immune pathways that lead to the induction of antiviral restriction factors. One such factor, viperin, was discovered almost two decades ago based on its induction during viral infection. Since then, viperin has been shown to possess activity against numerous viruses via multiple proposed mechanisms. Most recently, however, viperin was demonstrated to catalyze the conversion of cytidine triphosphate (CTP) to 3'-deoxy-3',4'-didehydro-CTP (ddhCTP), a previously unknown ribonucleotide. Incorporation of ddhCTP causes premature termination of RNA synthesis by the RNA-dependent RNA polymerase of some viruses. To date, production of ddhCTP by viperin represents the only activity of viperin that links its enzymatic activity directly to an antiviral mechanism in human cells. This review examines the multiple antiviral mechanisms and biological functions attributed to viperin.

Integrative Analyses of Genes Associated With Osteoporosis in CD16+ Monocyte

BACKGROUND

Osteoporosis is a metabolic bone disease characterized by decreased bone mineral density and abnormal bone quality. Monocytes can secret cytokines for bone resorption, resulting in bone mass loss. However, the mechanism by which monocytes subpopulations lead to osteoporosis remains unclear. The aim of this study was to identify genes associated with osteoporosis in monocytes subsets.

METHODS

Three microarray datasets including GSE7158 (transcription of low/high-peak bone mass), GSE101489 (transcription of CD16+/CD16- monocyte) and GSE93883 (miRNA expression profile of primary osteoporosis) were derived from the Gene Expression Omnibus (GEO) database and analyzed with GEO2R tool to identify differentially expressed genes (DEGs). Functional enrichment was analyzed using Metascape database and GSEA software. STRING was utilized for the Protein-Protein Interaction Network construct. The hub genes were screened out using the Cytoscape software. Related miRNAs were predicted in miRWalk, miRDB, and TargetScan databases.

RESULTS

Total 368 DEGs from GSE7158 were screened out, which were mostly enriched in signaling, positive regulation of biological process and immune system process. The hub genes were clustered into two modules by PPI network analysis. We identified 15 overlapping DGEs between GSE101489 and GSE7158 microarray datasets. Moreover, all of them were up-regulated genes in both datasets. Then, nine key genes were screened out from above 15 overlapping DEGs using Cytoscape software. It is a remarkable fact that the nine genes were all in one hub gene module of GSE7158. Additionally, 183 target miRNAs were predicted according to the above nine DEGs. After cross-verification with miRNA express profile dataset for osteoporosis (GSE93883), 12 DEmiRNAs were selected. Finally, a miRNA-mRNA network was constructed with the nine key genes and 12 miRNAs, which were involved in osteoporosis.

CONCLUSION

Our analysis results constructed a gene expression framework in monocyte subsets for osteoporosis. This approach could provide a novel insight into osteoporosis.

The antiviral protein viperin regulates chondrogenic differentiation via CXCL10 protein secretion

Viperin (also known as radical SAM domain–containing 2 (RSAD2)) is an interferon-inducible and evolutionary conserved protein that participates in the cell's innate immune response against a number of viruses. Viperin mRNA is a substrate for endoribonucleolytic cleavage by RNase mitochondrial RNA processing (MRP) and mutations in the RNase MRP small nucleolar RNA (snoRNA) subunit of the RNase MRP complex cause cartilage-hair hypoplasia (CHH), a human developmental condition characterized by metaphyseal chondrodysplasia and severe dwarfism. It is unknown how CHH-pathogenic mutations in RNase MRP snoRNA interfere with skeletal development, and aberrant processing of RNase MRP substrate RNAs is thought to be involved. We hypothesized that viperin plays a role in chondrogenic differentiation. Using immunohistochemistry, real-time quantitative PCR, immunoblotting, ELISA, siRNA-mediated gene silencing, plasmid-mediated gene overexpression, label-free MS proteomics, and promoter reporter bioluminescence assays, we discovered here that viperin is expressed in differentiating chondrocytic cells and regulates their protein secretion and the outcome of chondrogenic differentiation by influencing transforming growth factor β (TGF-β)/SMAD family 2/3 (SMAD2/3) activity via C-X-C motif chemokine ligand 10 (CXCL10). Of note, we observed disturbances in this viperin–CXCL10–TGF-β/SMAD2/3 axis in CHH chondrocytic cells. Our results indicate that the antiviral protein viperin controls chondrogenic differentiation by influencing secretion of soluble proteins and identify a molecular route that may explain impaired chondrogenic differentiation of cells from individuals with CHH.

Cardiac remodeling in response to embryonic crude oil exposure involves unconventional NKX family members and innate immunity genes

Cardiac remodeling results from both physiological and pathological stimuli. Compared to mammals, fish hearts show a broader array of remodeling changes in response to environmental influences, providing exceptional models for dissecting the molecular and cellular bases of cardiac remodeling. We recently characterized a form of pathological remodeling in juvenile pink salmon (Oncorhynchus gorbuscha) in response to crude oil exposure during embryonic cardiogenesis. In the absence of overt pathology (cardiomyocyte death or inflammatory infiltrate), cardiac ventricles in exposed fish showed altered shape, reduced thickness of compact myocardium, and hypertrophic changes in spongy, trabeculated myocardium. Here we used RNA sequencing to characterize molecular pathways underlying these defects. In juvenile ventricular cardiomyocytes, antecedent embryonic oil exposure led to dose-dependent up-regulation of genes involved in innate immunity and two NKX homeobox transcription factors not previously associated with cardiomyocytes, nkx2.3 and nkx3.3. Absent from mammalian genomes, the latter is largely uncharacterized. In zebrafish embryos nkx3.3 demonstrated a potent effect on cardiac morphogenesis, equivalent to nkx2.5, the primary transcription factor associated with ventricular cardiomyocyte identity. The role of nkx3.3 in heart growth is potentially linked to the unique regenerative capacity of fish and amphibians. Moreover, these findings support a cardiomyocyte-intrinsic role for innate immune response genes in pathological hypertrophy. This study demonstrates how an expanding mechanistic understanding of environmental pollution impacts – i.e., the chemical perturbation of biological systems – can ultimately yield new insights into fundamental biological processes.

Identification and functional characterization of viperin of amphioxus Branchiostoma japonicum: Implications for ancient origin of viperin-mediated antiviral response

Viperin, an antiviral protein, has been shown to be active against a wide range of DNA and RNA viruses, but no information is available regarding functional characterization of viperin in invertebrate species. In this study, we clearly demonstrate that amphioxus (Branchiostoma japonicum) viperin, BjVip, has features in common with those of vertebrate viperin, including the presence of the SAM superfamily domain with the characteristic CNYKCGFC motif, syntenic conservation, and predicted 3D structure. Bjvip exhibits a tissue-specific expression with abundant levels in the hepatic cecum, hind-gut, gill and muscle, and following challenge with the viral mimic poly I:C, its expression is significantly up-regulated, suggesting an involvement of BjVip in immune response of amphioxus against viral infection. Importantly, we show that the cells transfected with Bjvip is able to kill LCDV or inhibiting its propagation, and co-incubation of rBjVip with WSSV markedly attenuates its infectivity. Thus, we provide the first evidences that amphioxus viperin, like that of vertebrates, is capable of promoting resistance against viral infection in vitro and in vivo, indicating that viperin-mediated antiviral response already emerged in the primitive chordate. We also prove that amphioxus viperin has evolved under positive selection.

Differential Expression Profile of Chicken Embryo Fibroblast DF-1 Cells Infected with Cell-Adapted Infectious Bursal Disease Virus

RNA-Seq was used to unveil the transcriptional profile of DF-1 cells at the early stage of caIBDV infection. Total RNAs were extracted from virus-infected cells at 0, 6 and 12 hpi. RNA-Seq datasets of respective samples mapped to 56.5–57.6% of isoforms in the reference genome Galgal4.73. At 6 hpi, 23 isoforms underwent an elevated expression, while 128 isoforms were up-regulated and 5 were down-regulated at 12 hpi in the virus-infected group. Besides, 10 isoforms were exclusively expressed in the virus-infected cells. Though no significant change was detected in cytokine and interferon expression levels at the first 12 hours of infection, modulations of the upstream regulators were observed. In addition to the reported regulatory factors including EIF2AK2, MX, OAS*A, GBP7 and IFIT, IBDV infection also triggered a IFIT5-IRF1/3-RSAD5 pathway in the DF-1 cells which potentially restricted the viral replication cycle in the early infection stage. Over-expression of LIPA and CH25H, together with the suppression of STARD4, LSS and AACS genes implied a modulation of membrane fluidity and lipid raft arrangement in the infected cells. Alternative splicing of the EFR3 homolog A gene was also through to be involved in the lipid membrane regulation, and these cumulative responses projected an inhibition of viral endocytosis. Recognition of viral RNA genomes and intermediates was presumably enhanced by the elevated levels of IFIH1, DHX58 and TRIM25 genes which possess properties on detecting viral dsRNA. On the other hand, the caIBDV arrested the host's apoptotic process by inducing the expression of apoptosis inhibitors including NFKBIA/Z, TNFAIP2/3 and ITA at the first 12 hours of infection. In conclusion, the differential expression landscape demonstrated with RNA-Seq provides a comprehensive picture on the molecular interactions between host cells and virus at the early stage of infection.

SDF-1/CXCR4 axis in Tie2-lineage cells including endothelial progenitor cells contributes to bone fracture healing

CXC chemokine receptor 4 (CXCR4) is a specific receptor for stromal-derived-factor 1 (SDF-1). SDF-1/CXCR4 interaction is reported to play an important role in vascular development. On the other hand, the therapeutic potential of endothelial progenitor cells (EPCs) in fracture healing has been demonstrated with mechanistic insight of vasculogenesis/angiogenesis and osteogenesis enhancement at sites of fracture. The purpose of this study was to investigate the influence of the SDF-1/CXCR4 pathway in Tie2-lineage cells (including EPCs) in bone formation. We created CXCR4 gene conditional knockout mice using the Cre/loxP system and set two groups of mice: Tie2-Cre(ER) CXCR4 knockout mice (CXCR4(-/-) ) and wild-type mice (WT). We report here that in vitro, EPCs derived from of CXCR4(-/-) mouse bone marrow demonstrated severe reduction of migration activity and EPC colony-forming activity when compared with those derived from WT mouse bone marrow. In vivo, radiological and morphological examinations showed fracture healing delayed in the CXCR4(-/-) group and the relative callus area at weeks 2 and 3 was significantly smaller in CXCR4(-/-) group mice. Quantitative analysis of capillary density at perifracture sites also showed a significant decrease in the CXCR4(-/-) group. Especially, CXCR4(-/-) group mice demonstrated significant early reduction of blood flow recovery at fracture sites compared with the WT group in laser Doppler perfusion imaging analysis. Real-time RT-PCR analysis showed that the gene expressions of angiogenic markers (CD31, VE-cadherin, vascular endothelial growth factor [VEGF]) and osteogenic markers (osteocalcin, collagen 1A1, bone morphogenetic protein 2 [BMP2]) were lower in the CXCR4(-/-) group. In the gain-of-function study, the fracture in the SDF-1 intraperitoneally injected WT group healed significantly faster with enough callus formation compared with the SDF-1 injected CXCR4(-/-) group. We demonstrated that an EPC SDF-1/CXCR4 axis plays an important role in bone fracture healing using Tie2-Cre(ER) CXCR4 conditional knockout mice.

Fish viperin exerts a conserved antiviral function through RLR-triggered IFN signaling pathway

Mammalian viperin is a typical interferon (IFN)-induced antiviral protein. Fish have viperin homologs; however, little is known about the expression regulation of fish viperins. In this study, we report the expression regulation and antiviral function of a fish viperin from crucian carp Carassius auratus during IFN response. Crucian carp viperin is induced at mRNA and protein levels by fish IFNs and IFN stimuli such as poly(I:C). Consistently, this gene promoter contains multiple transcription factor binding sites including IFN-stimulated response elements (ISRE) and IFN gamma activation sequences (GAS), and is activated by two types of fish IFNs and also by the intracellular and extracellular poly(I:C). Activation of crucian carp viperin promoter by the intracellular poly(I:C) is mediated by retinoic acid-inducing gene I (RIG-I)-like receptors (RLR)-triggered IFN signaling pathway, which is further verified by the findings that each signaling molecule of RLR pathway is able to induce the expression of crucian carp viperin at mRNA and protein levels. Finally, overexpression of crucian carp viperin in cultured fish cells confers significant protection against infection of grass carp reovirus (GCRV). These data suggest that similar to mammalian homologs, crucian carp viperin exerts a conserved function through RLR-triggered IFN signaling pathway.

Safety Evaluation of Hypoallergenic Wheat Flour by Using a DNA Microarray

The effect of the consumption of hypoallergenic wheat flour (HWF) on the expression of a wide spectrum of genes was analyzed by using a DNA microarray. Gene expression profiles in the liver and intestines of rats fed on a diet composed mainly of HWF were compared with those of rats fed on a normal flour-based diet. Among the eight thousand transcripts represented on the GeneChip microarray, no more than 30 genes exhibited up- or down-regulation of two-fold or more after one week or two months of HWF consumption. No adverse effects were apparent. Up-regulation of some of the genes known to respond to the interferon-gamma signal was apparent in the one-week experiment, which may be related to possible oral immunotolerance resulting from HWF feeding. This DNA microarray technology presents an efficient method for evaluating the safety of foods.

Viperin, a key player in the antiviral response

Viperin is an antiviral protein that is induced by different viruses, type I interferon, poly(I:C) and lipopolysaccharide, which is localized to the endoplasmic reticulum and lipid droplets. Recently, our knowledge on the mechanism by which viperin inhibits viral replication has strongly increased. Interestingly, it also became clear that viperin can be used by viruses to increase their infectivity. Here, our current knowledge on the induction of viperin and its effect on virus replication will be reviewed.

Early antiviral response and virus-induced genes in fish

In fish as in mammals, virus infections induce changes in the expression of many host genes. Studies conducted during the last fifteen years revealed a major contribution of the interferon system in fish antiviral response. This review describes the screening methods applied to compare the impact of virus infections on the transcriptome in different fish species. These approaches identified a "core" set of genes that are strongly induced in most viral infections. The "core" interferon-induced genes (ISGs) are generally conserved in vertebrates, some of them inhibiting a wide range of viruses in mammals. A selection of ISGs -PKR, vig-1/viperin, Mx, ISG15 and finTRIMs - is further analyzed here to illustrate the diversity and complexity of the mechanisms involved in establishing an antiviral state. Most of the ISG-based pathways remain to be directly determined in fish. Fish ISGs are often duplicated and the functional specialization of multigenic families will be of particular interest for future studies.

Tympanic membrane wound healing in rats assessed by transcriptome profiling

OBJECTIVES/HYPOTHESIS

The aim of this study is to elucidate transcriptional changes that occur in response to tympanic membrane (TM) perforation in rats and to infer key genes and molecular events in the healing process.

STUDY DESIGN

A prospective cohort study of 393 male Sprague-Dawley (Rattus norvegicus) rats.

METHODS

Sprague-Dawley rats were randomly allocated into either control or perforation groups spanning a 7-day time period. Perforation groups consisted of 12-hour, 24-hour, 36-hour, 2-day, 3-day, 4-day, 5-day, six-day, and 7-day time points. The left TMs of all perforation groups were perforated and the RNA extracted at the specified time point postperforation. Subsequent analysis was performed using Agilent's 4 × 44 k whole rat genome arrays (40 in total) to assess wound-healing gene expression over a 7-day time period.

RESULTS

Over a 7-day time course and at nine time points that encompassed the wounding and progression of healing, a total of 3,262 genes were differentially expressed. In this study the transcripts most upregulated occurred at 12 hours. These were Stefin A2 (344-fold), Stefin 2 (143-fold), and Natriuretic peptide precursor type B (222-fold). Those most downregulated also occurred at 12 hours. These were alcohol dehydrogenase 7 (13.1-fold) and gamma-butyrobetaine hydroxylase (10.4-fold). Results were validated by quantitative real-time polymerase chain reaction.

CONCLUSIONS

The findings of this study provide a baseline against which to identify disease-related molecular signatures, biomarkers, and to develop new treatments for TM conditions based on molecular evidence.

Interferon-γ plays a role in bone formation in vivo and rescues osteoporosis in ovariectomized mice

Interferon γ (IFN-γ) is a cytokine produced locally in the bone microenvironment by cells of immune origin as well as mesenchymal stem cells. However, its role in normal bone remodeling is still poorly understood. In this study we first examined the consequences of IFN-γ ablation in vivo in C57BL/6 mice expressing the IFN-γ receptor knockout phenotype (IFNγR1(-/-)). Compared with their wild-type littermates (IFNγR1(+/+)), IFNγR1(-/-) mice exhibit a reduction in bone volume associated with significant changes in cortical and trabecular structural parameters characteristic of an osteoporotic phenotype. Bone histomorphometry of IFNγR1(-/-) mice showed a low-bone-turnover pattern with a decrease in bone formation, a significant reduction in osteoblast and osteoclast numbers, and a reduction in circulating levels of bone-formation and bone-resorption markers. Furthermore, administration of IFN-γ (2000 and 10,000 units) to wild-type C57BL/6 sham-operated (SHAM) and ovariectomized (OVX) female mice significantly improved bone mass and microarchitecture, mechanical properties of bone, and the ratio between bone formation and bone resorption in SHAM mice and rescued osteoporosis in OVX mice. These data therefore support an important physiologic role for IFN-γ signaling as a potential new anabolic therapeutic target for osteoporosis.

Maternal antioxidant supplementation prevents adiposity in the offspring of Western diet-fed rats

OBJECTIVE

Obesity in pregnancy significantly increases the risk of the offspring developing obesity after birth. The aims of this study were to test the hypothesis that maternal obesity increases oxidative stress during fetal development, and to determine whether administration of an antioxidant supplement to pregnant Western diet-fed rats would prevent the development of adiposity in the offspring.

RESEARCH DESIGN AND METHODS

Female Sprague Dawley rats were started on the designated diet at 4 weeks of age. Four groups of animals were studied: control chow (control); control + antioxidants (control+Aox); Western diet (Western); and Western diet + antioxidants (Western+Aox). The rats were mated at 12 to 14 weeks of age, and all pups were weaned onto control diet.

RESULTS

Offspring from dams fed the Western diet had significantly increased adiposity as early as 2 weeks of age as well as impaired glucose tolerance compared with offspring of dams fed a control diet. Inflammation and oxidative stress were increased in preimplantation embryos, fetuses, and newborns of Western diet-fed rats. Gene expression of proadipogenic and lipogenic genes was altered in fat tissue of rats at 2 weeks and 2 months of age. The addition of an antioxidant supplement decreased adiposity and normalized glucose tolerance. CONCLUSIONS; Inflammation and oxidative stress appear to play a key role in the development of increased adiposity in the offspring of Western diet-fed pregnant dams. Restoration of the antioxidant balance during pregnancy in the Western diet-fed dam is associated with decreased adiposity in offspring.

Viperin mRNA is a novel target for the human RNase MRP/RNase P endoribonuclease

RNase MRP is a conserved endoribonuclease, in humans consisting of a 267-nucleotide RNA associated with 7–10 proteins. Mutations in its RNA component lead to several autosomal recessive skeletal dysplasias, including cartilage-hair hypoplasia (CHH). Because the known substrates of mammalian RNase MRP, pre-ribosomal RNA, and RNA involved in mitochondrial DNA replication are not likely involved in CHH, we analyzed the effects of RNase MRP (and the structurally related RNase P) depletion on mRNAs using DNA microarrays. We confirmed the upregulation of the interferon-inducible viperin mRNA by RNAi experiments and this appeared to be independent of the interferon response. We detected two cleavage sites for RNase MRP/RNase P in the coding sequence of viperin mRNA. This is the first study providing direct evidence for the cleavage of a mRNA by RNase MRP/RNase P in human cells. Implications for the involvement in the pathophysiology of CHH are discussed.

n-3 Polyunsaturated fatty acids modulate carcinogen-directed non-coding microRNA signatures in rat colon

We have hypothesized that dietary modulation of intestinal non-coding RNA [microRNA (miRNA)] expression may contribute to the chemoprotective effects of nutritional bioactives (fish oil and pectin). To fully understand the effects of these agents on the expression of miRNAs, Sprague-Dawley rats were fed diets containing corn oil or fish oil with pectin or cellulose and injected with azoxymethane (AOM, a colon-specific carcinogen) or saline (control). Real-time polymerase chain reaction using miRNA-specific primers and Taq Man probes was carried out to quantify effects on miRNA expression in colonic mucosa. From 368 mature miRNAs assayed, at an early stage of cancer progression (10 week post AOM injection), let-7d, miR-15b, miR-107, miR-191 and miR-324-5p were significantly (P < 0.05) affected by diet x carcinogen interactions. Overall, fish oil fed animals exhibited the smallest number of differentially expressed miRNAs (AOM versus saline treatment). With respect to the tumor stage (34 week post AOM injection), 46 miRNAs were dysregulated in adenocarcinomas compared with normal mucosa from saline-injected animals. Of the 27 miRNAs expressed at higher (P < 0.05) levels in tumors, miR-34a, 132, 223 and 224 were overexpressed at >10-fold. In contrast, the expression levels of miR-192, 194, 215 and 375 were dramatically reduced (< or = 0.32-fold) in adenocarcinomas. These results demonstrate for the first time the utility of the rat AOM model and the novel role of fish oil in protecting the colon from carcinogen-induced miRNA dysregulation.

Identification of actively translated mRNA transcripts in a rat model of early-stage colon carcinogenesis

With respect to functional mapping of gene expression signatures, the steady-state mRNA expression level does not always accurately reflect the status of critical signaling proteins. In these cases, control is exerted at the epigenetic level of recruitment of mRNAs to polysomes, the factories of ribosomes that mediate efficient translation of many cellular messages. However, to date, a genome-wide perspective of the effect of carcinogen and chemoprotective bioactive diets on actively translated (polysomal) mRNA populations has not been done. Therefore, we used an established colon cancer model, i.e., the azoxymethane (AOM)-treated rat, in combination with a chemoprotective diet extensively studied in our laboratory, i.e., n-3 polyunsaturated fatty acids, to characterize the molecular processes underlying the transformation of normal colonic epithelium. The number of genes affected by AOM treatment 10 weeks after carcinogen injection was significantly greater in the polysome RNA fraction compared with the total RNA fraction as determined using a high-density microarray platform. In particular, polysomal loading patterns of mRNAs associated with the Wnt-beta catenin, phospholipase A(2)-eicosanoid and the mitogen-activated protein kinase signaling axes were significantly upregulated at a very early period of tumor development in the colon. These data indicate that translational alterations are far more extensive relative to transcriptional alterations in mediating malignant transformation. In contrast, transcriptional alterations were found to be more extensive relative to translational alterations in mediating the effects of diet. Therefore, during early stage colonic neoplasia, diet and carcinogen seem to predominantly regulate gene expression at multiple levels via unique mechanisms.

Development of an improved protocol to analyse gene expression in temporomandibular joint condylar cartilage of rats using DNA microarrays

PURPOSE

During recent years, gene expression analyses based on DNA chip technologies have allowed for the genome-wide identification of genes potentially associated with growth processes in a variety of organs. The present study aims to identify genes differentially expressed in the growing temporomandibular joint cartilage by means of transcriptome analyses.

MATERIAL AND METHODS

In total, the condylar cartilage of 32 rats comprising 4 age groups (newborn, 10 days, 21 days, 8 weeks) were used for analysis. Transcriptome analyses were carried out using Affymetrix Expression Arrays (Rat Genome 230 2.0 Arrays). The availability of high-quality RNA preparations from homogeneous tissue samples is a fundamental precondition of successful transcriptome analyses using DNA arrays. An optimised preparation protocol allowed RNA isolation of sufficient quality which was validated using capillary electrophoresis. RNA collected from 8 test animals of the 4 age groups respectively was mixed in equimolar RNA pools which served for the transcriptome analyses using Affymetrix arrays.

RESULTS

Statistical analysis of the gene expression data indicated the existence of genes differentially regulated in the growing temporomandibular cartilage. This evidence, however, requires validation by RT-PCR using individual animals' RNA. Preliminary candidate genes belong, among others, to the groups of matrix-degrading proteases, protease inhibitors and genes involved in cell growth, apoptosis and bone remodelling.

CONCLUSION

These differentially expressed genes in TMJ growth identified using DNA array technology may possibly contribute to a better understanding of growth biology and provide an approach to necessary therapy.

The Radical SAM Superfamily

The radical S-adenosylmethionine (SAM) superfamily currently comprises more than 2800 proteins with the amino acid sequence motif CxxxCxxC unaccompanied by a fourth conserved cysteine. The charcteristic three-cysteine motif nucleates a [4Fe-4S] cluster, which binds SAM as a ligand to the unique Fe not ligated to a cysteine residue. The members participate in more than 40 distinct biochemical transformations, and most members have not been biochemically characterized. A handful of the members of this superfamily have been purified and at least partially characterized. Significant mechanistic and structural information is available for lysine 2,3-aminomutase, pyruvate formate-lyase, coproporphyrinogen III oxidase, and MoaA required for molybdopterin biosynthesis. Biochemical information is available for spore photoproduct lyase, anaerobic ribonucleotide reductase activation subunit, lipoyl synthase, and MiaB involved in methylthiolation of isopentenyladenine-37 in tRNA. The radical SAM enzymes biochemically characterized to date have in common the cleavage of the [4Fe-4S](1 +) -SAM complex to [4Fe-4S](2 +)-Met and the 5' -deoxyadenosyl radical, which abstracts a hydrogen atom from the substrate to initiate a radical mechanism.

Differential effects of Th1, monocyte/macrophage and Th2 cytokine mixtures on early gene expression for glial and neural-related molecules in central nervous system mixed glial cell cultures: neurotrophins, growth factors and structural proteins

Background

In multiple sclerosis, inflammatory cells are found in both active and chronic lesions, and it is increasingly clear that cytokines are involved directly and indirectly in both formation and inhibition of lesions. We propose that cytokine mixtures typical of Th1 or Th2 lymphocytes, or monocyte/macrophages each induce unique molecular changes in glial cells.

Methods

To examine changes in gene expression that might occur in glial cells exposed to the secreted products of immune cells, we have used gene array analysis to assess the early effects of different cytokine mixtures on mixed CNS glia in culture. We compared the effects of cytokines typical of Th1 and Th2 lymphocytes and monocyte/macrophages (M/M) on CNS glia after 6 hours of treatment.

Results

In this paper we focus on changes with potential relevance for neuroprotection and axon/glial interactions. Each mixture of cytokines induced a unique pattern of changes in genes for neurotrophins, growth and maturation factors and related receptors; most notably an alternatively spliced form of trkC was markedly downregulated by Th1 and M/M cytokines, while Th2 cytokines upregulated BDNF. Genes for molecules of potential importance in axon/glial interactions, including cell adhesion molecules, connexins, and some molecules traditionally associated with neurons showed significant changes, while no genes for myelin-associated genes were regulated at this early time point. Unexpectedly, changes occurred in several genes for proteins initially associated with retina, cancer or bone development, and not previously reported in glial cells.

Conclusion

Each of the three cytokine mixtures induced specific changes in gene expression that could be altered by pharmacologic strategies to promote protection of the central nervous system.

The interferon-inducible protein viperin inhibits influenza virus release by perturbing lipid rafts

Interferons initiate the host antiviral response by inducing a number of genes, most with no defined antiviral function. Here we show that the interferon-induced protein viperin inhibits influenza A virus release from the plasma membrane of infected cells. Viperin expression altered plasma membrane fluidity by affecting the formation of lipid rafts, which are detergent-resistant membrane microdomains known to be the sites of influenza virus budding. Intracellular interaction of viperin with farnesyl diphosphate synthase (FPPS), an enzyme essential for isoprenoid biosynthesis, decreased the activity of the enzyme. Overexpression of FPPS reversed viperin-mediated inhibition of virus production and restored normal membrane fluidity, and reduction of FPPS levels by siRNA inhibited virus release and replication, indicating that the FPPS interaction underlies viperin's effects. These findings suggest that targeting the release stage of the life cycle may affect the replication of many enveloped viruses. Furthermore, FPPS may be an attractive target for antiviral therapy.

Chitosan monomer accelerates alkaline phosphatase activity on human osteoblastic cells under hypofunctional conditions

Chitosan is a natural polyaminosaccharide that is extensively applied as an antitumor and antirheumatic drug. However, there are few reports about its effects on hypofunctional osteoblasts in vitro. We investigated the biological characteristics of a human osteoblastic cell line (NOS-1 cells) that was cultured with a chitosan monomer-containing medium under simulated microgravity conditions. After 7 days of cell incubation under the conventional conditions, the flasks were transferred to a microgravity simulator for 3 days. In the 0.005% chitosan monomer supplemented group, the marker enzyme of biological mineralization, the alkaline phosphatase (ALP) activity, was significantly higher compared with the control group (p<0.05). A cDNA microarray was performed to investigate the effects on the mRNA level by chitosan monomer, and the fluorescent signal was analyzed. The interferon gamma (IFN-gamma) receptor gene was detected with a signal ration of 2.2. The slight increase of IFN-gamma receptor expression was confirmed after 3 days of incubation according to RT-PCR analysis. Western blot analysis also showed the increased expression of IFN-gamma receptor. These results suggest that a supra-low concentration of chitosan monomer may increase the ALP activity of osteoblastic cells through the IFN-gamma receptor at the early phase of cell culture and recover the activity for biological mineralization under the hypofunctional condition.

Arthritis suppression by NADPH activation operates through an interferon-beta pathway

BACKGROUND

A polymorphism in the activating component of the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase complex, neutrophil cytosolic factor 1 (NCF1), has previously been identified as a regulator of arthritis severity in mice and rats. This discovery resulted in a search for NADPH oxidase-activating substances as a potential new approach to treat autoimmune disorders such as rheumatoid arthritis (RA). We have recently shown that compounds inducing NCF1-dependent oxidative burst, e.g. phytol, have a strong ameliorating effect on arthritis in rats. However, the underlying molecular mechanism is still not clearly understood. The aim of this study was to use gene-expression profiling to understand the protective effect against arthritis of activation of NADPH oxidase in the immune system.

RESULTS

Subcutaneous administration of phytol leads to an accumulation of the compound in the inguinal lymph nodes, with peak levels being reached approximately 10 days after administration. Hence, global gene-expression profiling on inguinal lymph nodes was performed 10 days after the induction of pristane-induced arthritis (PIA) and phytol administration. The differentially expressed genes could be divided into two pathways, consisting of genes regulated by different interferons. IFN-gamma regulated the pathway associated with arthritis development, whereas IFN-beta regulated the pathway associated with disease protection through phytol. Importantly, these two molecular pathways were also confirmed to differentiate between the arthritis-susceptible dark agouti (DA) rat, (with an Ncf-1DA allele that allows only low oxidative burst), and the arthritis-protected DA.Ncf-1E3 rat (with an Ncf1E3 allele that allows a stronger oxidative burst).

CONCLUSION

Naturally occurring genetic polymorphisms in the Ncf-1 gene modulate the activity of the NADPH oxidase complex, which strongly regulates the severity of arthritis. We now show that the Ncf-1 allele that enhances oxidative burst and protects against arthritis is operating through an IFN-beta-associated pathway, whereas the arthritis-driving allele operates through an IFN-gamma-associated pathway. Treatment of arthritis-susceptible rats with an NADPH oxidase-activating substance, phytol, protects against arthritis. Interestingly, the treatment led to a restoration of the oxidative-burst effect and induction of a strikingly similar IFN-beta-dependent pathway, as seen with the disease-protective Ncf1 polymorphism.

Effects of Interferon-Gamma on Bone Remodeling during Experimental Tooth Movement

Objective: To determine the effects of interferon-gamma (IFN-γ) on bone remodeling during orthodontic tooth movement.

Materials and Methods: Thirty adult male Sprague Dawley rats were randomly categorized into five groups. IFN-γ was administered in three different doses (0.01, 0.02, and 0.05 μg/20 μL) and the remaining two groups served as control. Mandibular first molars were moved mesially by means of Ni-Ti closed coil springs in all groups. The results were evaluated histomorphometrically, and parameters of trabecular bone volume (BV/TV), trabecular bone number (Tr.N), and trabecular separation (Tr.Sep) were observed at the interradicular bone area of the mandibular first molars.

Results: Increases in BV/TV and Tr.N and decreases in Tr.Sep revealed the antiosteoclastic activity of IFN-γ.

Conclusion: IFN-γ administration may be useful clinically for anchorage control.

Effect of interferon-alpha-2b on porcine mesenchymal stem cells

PURPOSE

Patients undergoing enucleation and adjuvant interferon therapy for giant cell jaw tumors have been observed to exhibit exuberant bone formation in the resultant defects. We hypothesize that interferon promotes bone formation by enhancing mesenchymal stem cell (MSC) differentiation and by stimulating osteoblasts. This is a preliminary study to determine the effects of interferon on porcine mesenchymal stem cells (pMSCs) in culture.

MATERIALS AND METHODS

Isolated pMSCs were grown under the following conditions: 1) MSCs alone (negative control); 2) MSCs + osteogenic supplements (positive control); and 3) MSCs + interferon (experimental). Cell cultures were evaluated morphologically, by quantitative DNA analysis, and quantitative and qualitative alkaline phosphatase analysis.

RESULTS

Cells treated with interferon exhibited a slower but constant proliferation rate, did not clump, and produced more alkaline phosphatase as compared with the negative control.

CONCLUSION

The data indicate that interferon may act to differentiate MSCs into osteoblasts and to stimulate metabolic activity while not increasing the proliferation rate.

Characterization of ischemia/reperfusion-induced gene expression in experimental pancreas transplantation

BACKGROUND

The aim of this study was to identify genes that are differentially expressed in the early period after pancreatic cold ischemia/reperfusion (I/R) injury.

METHODS

Grafts of isogeneic rat pancreaticoduodenal transplantation were subjected to different preservation solutions and cold ischemia times (CITs): University of Wisconsin (UW), 6-hour CIT; UW, 18-hour CIT; and physiologic saline solution, 6-hour CIT. Animals that did not receive transplants served as controls. At 2-hour reperfusion, grafts were removed and pancreatic RNA was isolated, pooled, and hybridized to Affymetrix RG-U34A arrays. Quantitative reverse-transcription polymerase chain reaction was used to confirm the results of microarray technology.

RESULTS

A total of 49 genes were consistently upregulated (more than threefold) in all three groups of transplant recipient animals. Prominent genes include transcription factors; cytoskeletal factors; heat-shock proteins (e.g. Hsp27, Hsp90); molecules involved in inflammation (e.g. PAPIII), immunology, signal transduction, and translation; and genes that have not been associated with I/R injury so far (e.g. Best5). Messenger RNA levels of some genes were exclusively downregulated in response to the different conditions applied to the pancreatic grafts: Cybb, Reg3a, Per2, BMAL1, MAP, and Isl2.

CONCLUSIONS

These results provide new insight in I/R-induced gene expression after experimental pancreas transplantation. The reported upregulation of heat shock proteins, Best5, and PAPIII may play a pathologic role in pancreatic cold I/R injury and could therefore provide a promising perspective for further investigations.

Gastric inflammation, metaplasia, and tumor development in gastrin-deficient mice

BACKGROUND & AIMS

Gastrin deficiency and proton pump inhibitor treatment cause achlorhydria, which predisposes to disease. To elucidate the underlying molecular biology, we examined the changes in gastric gene expression in both types of achlorhydria. We also explored the associated changes in the gastric microflora and the long-term consequences of gastrin-deficient achlorhydria.

METHODS

Expression profiles were generated from gastric RNA from wild-type mice, gastrin knockout (KO) mice, gastrin KO mice after 1 week of gastrin infusion, and wild-type mice treated for 1 month with a proton pump inhibitor. The results were confirmed using real-time polymerase chain reaction and immunohistochemistry. Selective media were used to characterize the gastric microflora.

RESULTS

The number of gastric bacteria was increased in both gastrin KO and PPI-treated mice. The expression profiles revealed activation of immune defense genes, interferon-regulated response genes, and intestinal metaplasia of the gastric mucosa. In young gastrin-deficient mice, gastrin infusions reversed the changes. Over time, the changes accumulated, became irreversible, and progressed into metaplasia and polyp development. Finally, the study showed that gastrin regulated the expression of genes encoding extracellular matrix proteins.

CONCLUSIONS

Independently of gastrin, achlorhydria is associated with gastric bacterial overgrowth and intestinal gene expression patterns and is associated with predisposition to disease. Gastrin is therefore essential for prevention of gastric disease, mainly through control of acid secretion but to a lesser extent also through control of gastric gene expression. The gastrin-deficient mouse serves as a useful new model for gastric metaplasia and neoplasia.

Differential gene expression profiling in whole blood during acute systemic inflammation in lipopolysaccharide-treated rats

Microarrays have been used to evaluate the expression of thousands of genes in various tissues. However, few studies have investigated the change in gene expression profiles in one of the most easily accessible tissues, whole blood. We utilized an acute inflammation model to investigate the possibility of using a cDNA microarray to measure the gene expression profile in the cells of whole blood. Blood was collected from male Sprague-Dawley rats at 2 and 6 h after treatment with 5 mg/kg (ip) LPS. Hematology showed marked neutrophilia accompanied by lymphopenia at both time points. TNF-alpha and IL-6 levels were markedly elevated at 2 h, indicating acute inflammation, but by 6 h the levels had declined. Total RNA was isolated from whole blood and hybridized to the National Institute of Environmental Health Sciences Rat Chip v.3.0. LPS treatment caused 226 and 180 genes to be differentially expressed at 2 and 6 h, respectively. Many of the differentially expressed genes are involved in inflammation and the acute phase response, but differential expression was also noted in genes involved in the cytoskeleton, cell adhesion, oxidative respiration, and transcription. Real-time RT-PCR confirmed the differential regulation of a representative subset of genes. Principal component analysis of gene expression discriminated between the acute inflammatory response apparent at 2 h and the observed recovery underway at 6 h. These studies indicate that, in whole blood, changes in gene expression profiles can be detected that are reflective of inflammation, despite the adaptive shifts in leukocyte populations that accompany such inflammatory processes.

Early high expression of IP-10 in F344 rats resistant to Sendai virus-induced airway injury

Weanling F344 and BN rats differ markedly in their susceptibility to Sendai virus-induced airway injury. Early gene expression that controls their differences in susceptibility remains poorly understood. In this study we combined suppressive subtractive hybridization and cDNA library array hybridization to identify genes differentially expressed in virus-susceptible BN and virus-resistant F344 rats during the first 3 days after inoculation. Differential expression of selected clones was further verified by quantitative RT-PCR. Seven virus-induced gene segments were identified. Of them, interferon-gamma-inducible protein 10 (IP-10), Mx1, and guanylate-binding protein-2 mRNA abundance in infected F344 rats was 201.5, 188.2, and 281.7% higher, respectively, than that of infected BN rats at 2 days after inoculation. In situ hybridization indicated that virus-induced IP-10 was expressed mainly in airway epithelial cells of F344 rats. Sendai virus infection can directly induce IP-10 expression in rat tracheal epithelial cells in vitro. IP-10 early high expression might contribute to the resistance to virus-induced airway disease in F344 rats by promoting Th1 responses and increasing antiviral activity.

Cloning and characterization of osteoactivin, a novel cDNA expressed in osteoblasts

Osteoblast development is a complex process involving the expression of specific growth factors and regulatory proteins that control cell proliferation, differentiation, and maturation. In this study, we used the rat mutation, osteopetrosis (op), to examine differences in skeletal gene expression between mutant op and normal littermates. Total RNA isolated from long bone and calvaria was used as a template for mRNA differential display. One of many cDNAs that were selectively expressed in either normal or mutant bone was cloned and sequenced and found to share some homology to the human nmb and Pmel 17 genes. This novel cDNA was named osteoactivin. Osteoactivin has an open reading frame of 1716 bp that encodes a protein of 572 amino acids with a predicted molecular weight of 63.8 kD. Protein sequence analysis revealed the presence of a signal peptide and a cleavage site at position 23. The protein also has thirteen predicted N-linked glycosylation sites and a potential RGD integrin recognition site at position 556. Northern blot analysis confirmed that osteoactivin was 3- to 4-fold overexpressed in op versus normal bone. RT-PCR analysis showed that osteoactivin is most highly expressed in bone compared with any of the other non-osseous tissues examined. In situ hybridization analysis of osteoactivin in normal bone revealed that it is primarily expressed in osteoblasts actively engaged in bone matrix production and mineralization. In primary rat osteoblast cultures, osteoactivin showed a temporal pattern of expression being expressed at highest levels during the later stages of matrix maturation and mineralization and correlated with the expression of alkaline phosphatase and osteocalcin. Our findings show that osteoactivin expression in bone is osteoblast-specific and suggest that it may play an important role in osteoblast differentiation and matrix mineralization. Furthermore, osteoactivin overexpression in op mutant bone may be secondary to the uncoupling of bone resorption and formation resulting in abnormalities in osteoblast gene expression and function.

Viperin (cig5), an IFN-inducible antiviral protein directly induced by human cytomegalovirus

Little is known about the mechanism by which IFNs inhibit human cytomegalovirus (HCMV) replication. Indeed, infection of fibroblasts with HCMV initiates the expression of a subset of type I IFN-inducible genes whose role in the infectious process is unclear. We describe here the identification of a cytoplasmic antiviral protein that is induced by IFNs, by HCMV infection, and by the HCMV envelope protein, glycoprotein B (gB). Stable expression of the protein in fibroblasts inhibits productive HCMV infection, down-regulating several HCMV structural proteins (gB, pp28, and pp65) known to be indispensable for viral assembly and maturation. We have named the protein viperin (for virus inhibitory protein, endoplasmic reticulum-associated, interferon-inducible). HCMV infection causes the redistribution of the induced viperin from its normal endoplasmic reticulum association, first to the Golgi apparatus and then to cytoplasmic vacuoles containing gB and pp28. Expression before HCMV infection reduces viperin redistribution from the endoplasmic reticulum to the Golgi apparatus and prevents vacuolar localization, perhaps reflecting the mechanism used by HCMV to evade the antiviral function.

Radical SAM, a novel protein superfamily linking unresolved steps in familiar biosynthetic pathways with radical mechanisms: functional characterization using new analysis and information visualization methods

A novel protein superfamily with over 600 members was discovered by iterative profile searches and analyzed with powerful bioinformatics and information visualization methods. Evidence exists that these proteins generate a radical species by reductive cleavage of S:-adenosylmethionine (SAM) through an unusual Fe-S center. The superfamily (named here Radical SAM) provides evidence that radical-based catalysis is important in a number of previously well- studied but unresolved biochemical pathways and reflects an ancient conserved mechanistic approach to difficult chemistries. Radical SAM proteins catalyze diverse reactions, including unusual methylations, isomerization, sulfur insertion, ring formation, anaerobic oxidation and protein radical formation. They function in DNA precursor, vitamin, cofactor, antibiotic and herbicide biosynthesis and in biodegradation pathways. One eukaryotic member is interferon-inducible and is considered a candidate drug target for osteoporosis; another is observed to bind the neuronal Cdk5 activator protein. Five defining members not previously recognized as homologs are lysine 2,3-aminomutase, biotin synthase, lipoic acid synthase and the activating enzymes for pyruvate formate-lyase and anaerobic ribonucleotide reductase. Two functional predictions for unknown proteins are made based on integrating other data types such as motif, domain, operon and biochemical pathway into an organized view of similarity relationships.

Subtractive hybridization--genetic takeaways and the search for meaning

Gene expression profiling relies on mRNA extraction from defined cell systems, which in the case of pathological processes necessarily results in the use of small quantities of tissues, sometimes as little as a few cells. This obviates the use of many systems of gene expression profiling and is best carried out using cDNA amplified by poly(A) reverse transcription polymerase chain reaction, which is capable of generating material representative of all the expressed genes in samples as small as one cell. Analysis of this material using subtractive hybridization compares the genes expressed at different stages of a biological/pathological process allowing identification of the all the genes upregulated during the process. The identification of the genes present is not dependent on their prior description or on the choice of genes used in a screen and as such the method is ideal for identifying novel genes or unsuspected genes. We have used the method to identify genes involved in normal osteoblastic differentiation and in Paget's disease of bone and it has been widely used to study normal differentiation and pathological processes in a number of systems. The method, its applications and its relationship with the other methods of gene expression profiling are reviewed.

Massive parallel gene expression profiling of RINm5F pancreatic islet beta-cells stimulated with interleukin-1beta

Interleukin 1 (IL-1) is a pleiotropic cytokine with the potential to kill pancreatic beta-cells, and this unique property is thought to be involved in the pathogenesis of type I diabetes mellitus. We therefore determined the quantitative expression of 24,000 mRNAs of RINm5F, an insulinoma cell line derived from rat pancreatic beta-cells, before and after challenge with 30 and 1,000 pg/ml of recombinant human IL-1beta. The highest concentration resulted in decreased insulin production and cell death over a period of 4 days. Using three different time points, 2, 4 and 24 hours after challenge, we found that 146 full-length genes and a large number of expressed sequence tags were differentially regulated 3-fold or more. Most of the differentially regulated transcripts have not previously been described to be regulated by IL-1beta in beta-cells. We have analysed the expression data and sorted the genes into groups according to functional relations on the basis of knowledge of the structure or function ascribed to the individual genes. Many of the differentially regulated genes are known to play a role in immune- and stress-related pathways as well as in insulin secretion and vesicle trafficking, e.g. alpha-endosulfine and K+ channel Kir6.2 are differentially regulated. A number of transcripts in the biosynthesis pathway for cholesterol are also differentially regulated.

Vesicular stomatitis virus and pseudorabies virus induce a vig1/cig5 homologue in mouse dendritic cells via different pathways

The homologous genes vig1 and cig5 were identified by differential display PCR as virus-induced genes in rainbow trout and humans, respectively. These genes are significantly related to sequences required for the biosynthesis of metal cofactors, but their function remains unknown. In this study, it is shown that the mouse homologue of vig1/cig5 was induced by vesicular stomatitis virus (VSV) and pseudorabies virus (PrV) in mouse spleen cells. Among a collection of cell lines from dendritic, myeloid, lymphoid or fibroblast lineages, only the dendritic cell line, D2SC1, showed expression of mvig after virus infection. This dendritic restriction was confirmed by our finding that mvig was also induced by both VSV and PrV in CD11c(++) spleen cells, separated by magnetic purification or derived from bone marrow precursor cells. Similar to the fish rhabdovirus viral haemorrhagic septicaemia virus in trout cells, VSV directly induced mvig in the dendritic cell line D2SC1, but the PrV-mediated induction required the integrity of the interferon pathway. This result indicates that mvig is interferon-inducible like its fish and human homologues. Furthermore, mvig was also induced by LPS in bone marrow-derived cells. Thus, mvig expression seems to correlate with an activated state of dendritic cells subjected to different pathogen-associated stimuli.