The 2-5A system in viral infection and apoptosis

Effect of cannabidiol on apoptosis and cellular interferon and interferon-stimulated gene responses to the SARS-CoV-2 genes ORF8, ORF10 and M protein

AIMS

To study effects on cellular innate immune responses to ORF8, ORF10, and Membrane protein (M protein) from the Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that causes COVID-19, in combination with cannabidiol (CBD).

MAIN METHODS

HEK293 cells transfected with plasmids expressing control vector, ORF8, ORF10, or M protein were assayed for cell number and markers of apoptosis at 24 h, and interferon and interferon-stimulated gene expression at 14 h, with or without CBD. Cells transfected with polyinosinic:polycytidylic acid (Poly (I:C)) were also studied as a general model of RNA-type viral infection.

KEY FINDINGS

Reduced cell number and increased early and late apoptosis were found when expression of viral genes was combined with 1-2 μM CBD treatment, but not in control-transfected cells treated with CBD, or in cells expressing viral genes but treated only with vehicle. In cells expressing viral genes, CBD augmented expression of IFNγ, IFNλ1 and IFNλ2/3, as well as the 2'-5'-oligoadenylate synthetase (OAS) family members OAS1, OAS2, OAS3, and OASL. CBD also augmented expression of these genes in control cells not expressing viral genes, but without enhancing apoptosis. CBD similarly enhanced the cellular anti-viral response to Poly (I:C).

SIGNIFICANCE

Our results demonstrate a poor ability of HEK293 cells to respond to SARS-CoV-2 genes alone, but an augmented innate anti-viral response to these genes in the presence of CBD. Thus, CBD may prime components of the innate immune system, increasing readiness to respond to RNA-type viral infection without activating apoptosis, and could be studied for potential in prophylaxis.

African Swine Fever Virus CD2v Protein Induces β-Interferon Expression and Apoptosis in Swine Peripheral Blood Mononuclear Cells

African swine fever (ASF) is a hemorrhagic disease of swine characterized by massive lymphocyte depletion in lymphoid tissues due to the apoptosis of B and T cells, a process likely triggered by factors released or secreted by infected macrophages. ASFV CD2v (EP402R) has been implicated in viral virulence and immunomodulation in vitro; however, its actual function(s) remains unknown. We found that CD2v expression in swine PK15 cells induces NF-κB-dependent IFN-β and ISGs transcription and an antiviral state. Similar results were observed for CD2v protein treated swine PBMCs and macrophages, the major ASFV target cell. Notably, treatment of swine PBMCs and macrophages with CD2v protein induced apoptosis. Immunoprecipitation and colocalization studies revealed that CD2v interacts with CD58, the natural host CD2 ligand. Additionally, CD58 knockdown in cells or treatment of cells with an NF-κB inhibitor significantly reduced CD2v-mediated NF-κB activation and IFN-β induction. Further, antibodies directed against CD2v inhibited CD2v-induced NF-κB activation and IFN-β transcription in cells. Overall, results indicate that ASFV CD2v activates NF-κB, which induces IFN signaling and apoptosis in swine lymphocytes/macrophages. We propose that CD2v released from infected macrophages may be a significant factor in lymphocyte apoptosis observed in lymphoid tissue during ASFV infection in pigs.

ADAR1: "Editor-in-Chief" of Cytoplasmic Innate Immunity

Specialized receptors that recognize molecular patterns such as double stranded RNA duplexes-indicative of viral replication-are potent triggers of the innate immune system. Although their activation is beneficial during viral infection, RNA transcribed from endogenous mobile genetic elements may also act as ligands potentially causing autoimmunity. Recent advances indicate that the adenosine deaminase ADAR1 through RNA editing is involved in dampening the canonical antiviral RIG-I-like receptor-, PKR-, and OAS-RNAse L pathways to prevent autoimmunity. However, this inhibitory effect must be overcome during viral infections. In this review we discuss ADAR1's critical role in balancing immune activation and self-tolerance.

Interferon-Stimulated Genes-Mediators of the Innate Immune Response during Canine Distemper Virus Infection

The demyelinating canine distemper virus (CDV)-leukoencephalitis represents a translational animal model for multiple sclerosis. The present study investigated the expression of type I interferon (IFN-I) pathway members in CDV-induced cerebellar lesions to gain an insight into their role in lesion development. Gene expression of 110 manually selected genes in acute, subacute and chronic lesions was analyzed using pre-existing microarray data. Interferon regulatory factor (IRF) 3, IRF7, signal transducer and activator of transcription (STAT) 1, STAT2, MX protein, protein kinase R (PKR), 2'-5'-oligoadenylate synthetase (OAS) 1 and interferon-stimulated gene (ISG) 15 expression were also evaluated using immunohistochemistry. Cellular origin of STAT1, STAT2, MX and PKR were determined using immunofluorescence. CDV infection caused an increased expression of the antiviral effector proteins MX, PKR, OAS1 and ISG15, which probably contributed to a restricted viral replication, particularly in neurons and oligodendrocytes. This increase might be partly mediated by IRF-dependent pathways due to the lack of changes in IFN-I levels and absence of STAT2 in astrocytes. Nevertheless, activated microglia/macrophages showed a strong expression of STAT1, STAT2 and MX proteins in later stages of the disease, indicating a strong activation of the IFN-I signaling cascade, which might be involved in the aggravation of bystander demyelination.

OAS1, OAS2 and OAS3 restrict intracellular M. tb replication and enhance cytokine secretion

The 2',5' (OASs) are known as mediators of the antiviral response system through activation of the RNA cleavage pathway. Interestingly, we observe OAS1, OAS2 and OAS3 upregulation in a number of gene expression signatures which discriminate active TB from latent TB infection, however their biological role during bacterial infection has not yet been elucidated. We observed that the expression of these genes was associated with pathogenicity and virulence of mycobacteria as infection with Mycobacterium bovis BCG failed to significantly induce OAS expression. Further, we observed that after silencing of these genes, M. tb CFU counts increased significantly 96h post-infection in comparison to the respective controls. Luminex revealed that OAS silencing significantly decreased IL-1β, TNF-α and MCP-1 and had no effect of IL-10 secretion. We show for the first time that OAS1, 2 and 3 restrict intracellular pathogenic mycobacterial replication and enhance pro-inflammatory cytokine secretion.

ADAR1 and PKR, interferon stimulated genes with clashing effects on HIV-1 replication

The induction of hundreds of Interferon Stimulated Genes (ISGs) subsequent to virus infection generates an antiviral state that functions to restrict virus growth at multiple steps of their replication cycles. In the context of Human Immunodeficiency Virus-1 (HIV-1), ISGs also possess antiviral functions, but some ISGs show proapoptotic or proviral activity. One of the most studied ISGs, the RNA activated Protein Kinase (PKR), shuts down the viral protein synthesis upon activation. HIV-1 has evolved to evade its inhibition by PKR through viral and cellular mechanisms. One of the cellular mechanisms is the induction of another ISG, the Adenosine Deaminase acting on RNA 1 (ADAR1). ADAR1 promotes viral replication by acting as an RNA sensing inhibitor, by editing viral RNA and by inhibiting PKR. This review challenges the orthodox dogma of ISGs as antiviral proteins, by demonstrating that two ISGs have opposing and clashing effects on viral replication.

Efficacy of novel antibody-based drugs against rhinovirus infection: In vitro and in vivo results

Rhinoviruses (RVs) cause the common cold and are associated with exacerbations of chronic inflammatory respiratory diseases, especially asthma and chronic obstructive pulmonary disease (COPD). We have assessed the antiviral drugs Anaferon for Children (AC) and Ergoferon (containing AC as one of the active pharmaceutical ingredients) in in vitro and in vivo experimental models, in order to evaluate their anti-rhinoviral and immunomodulatory potential. HeLa cells were pretreated with AC, and levels of the interferon-stimulated gene (ISG), 2'-5'-oligoadenylate synthetase 1 (OAS1-A) and viral replication were analyzed. In a mouse model of RV-induced exacerbation of allergic airway inflammation we administered Ergoferon and analyzed its effect on type I (IFN-β), type II (IFN-γ) and type III (IFN-λ) IFNs induction, cell counts in bronchoalveolar lavage (BAL), cytokine (interleukin (IL)-4; IL-6) and chemokine (CXCL10/IP-10; CXCL1/KC) levels. It was shown that AC increased OAS1-А production and significantly decreased viral replication in vitro. Increased IFNs expression together with reduced neutrophils/lymphocytes recruitment and correlated IL-4/IL-6 declination was demonstrated for Ergoferon in vivo. However, there was no effect on examined chemokines. We conclude that AC and Ergoferon possess effects against RV infection and may have potential as novel therapies against RV-induced exacerbations of asthma.

Activation of RNase L by Murine Coronavirus in Myeloid Cells Is Dependent on Basal Oas Gene Expression and Independent of Virus-Induced Interferon

The oligoadenylate synthetase (OAS)-RNase L pathway is a potent interferon (IFN)-induced antiviral activity. Upon sensing double-stranded RNA, OAS produces 2',5'-oligoadenylates (2-5A), which activate RNase L. Murine coronavirus (mouse hepatitis virus [MHV]) nonstructural protein 2 (ns2) is a 2',5'-phosphodiesterase (PDE) that cleaves 2-5A, thereby antagonizing RNase L activation. PDE activity is required for robust replication in myeloid cells, as a mutant of MHV (ns2(H126R)) encoding an inactive PDE fails to antagonize RNase L activation and replicates poorly in bone marrow-derived macrophages (BMM), while ns2(H126R) replicates to high titer in several types of nonmyeloid cells, as well as in IFN receptor-deficient (Ifnar1(-/-)) BMM. We reported previously that myeloid cells express significantly higher basal levels of OAS transcripts than nonmyeloid cells. Here, we investigated the contributions of Oas gene expression, basal IFN signaling, and virus-induced IFN to RNase L activation. Infection with ns2(H126R) activated RNase L in Ifih1(-/-) BMM to a similar extent as in wild-type (WT) BMM, despite the lack of IFN induction in the absence of MDA5 expression. However, ns2(H126R) failed to induce RNase L activation in BMM treated with IFNAR1-blocking antibody, as well as in Ifnar1(-/-) BMM, both expressing low basal levels of Oas genes. Thus, activation of RNase L does not require virus-induced IFN but rather correlates with adequate levels of basal Oas gene expression, maintained by basal IFN signaling. Finally, overexpression of RNase L is not sufficient to compensate for inadequate basal OAS levels.

IMPORTANCE

The oligoadenylate synthetase (OAS)-RNase L pathway is a potent antiviral activity. Activation of RNase L during murine coronavirus (mouse hepatitis virus [MHV]) infection of myeloid cells correlates with high basal Oas gene expression and is independent of virus-induced interferon secretion. Thus, our data suggest that cells with high basal Oas gene expression levels can activate RNase L and thereby inhibit virus replication early in infection upon exposure to viral double-stranded RNA (dsRNA) before the induction of interferon and prior to transcription of interferon-stimulated antiviral genes. These findings challenge the notion that activation of the OAS-RNase L pathway requires virus to induce type I IFN, which in turn upregulates OAS gene expression, as well as to provide dsRNA to activate OAS. Our data further suggest that myeloid cells may serve as sentinels to restrict viral replication, thus protecting other cell types from infection.

Dengue Virus Control of Type I IFN Responses: A History of Manipulation and Control

The arthropod-borne diseases caused by dengue virus (DENV) are a major and emerging problem of public health worldwide. Infection with DENV causes a series of clinical manifestations ranging from mild flu syndrome to severe diseases that include hemorrhage and shock. It has been demonstrated that the innate immune response plays a key role in DENV pathogenesis. However, in recent years, it was shown that DENV evades the innate immune response by blocking type I interferon (IFN-I). It has been demonstrated that DENV can inhibit both the production and the signaling of IFN-I. The viral proteins, NS2A and NS3, inhibit IFN-I production by degrading cellular signaling molecules. In addition, the viral proteins, NS2A, NS4A, NS4B, and NS5, can inhibit IFN-I signaling by blocking the phosphorylation of the STAT1 and STAT2 molecules. Finally, NS5 mediates the degradation of STAT2 using the proteasome machinery. In this study, we briefly review the most recent insights regarding the IFN-I response to DENV infection and its implication for pathogenesis.

Late multiple organ surge in interferon-regulated target genes characterizes staphylococcal enterotoxin B lethality

Background

Bacterial superantigens are virulence factors that cause toxic shock syndrome. Here, the genome-wide, temporal response of mice to lethal intranasal staphylococcal enterotoxin B (SEB) challenge was investigated in six tissues.

Results

The earliest responses and largest number of affected genes occurred in peripheral blood mononuclear cells (PBMC), spleen, and lung tissues with the highest content of both T-cells and monocyte/macrophages, the direct cellular targets of SEB. In contrast, the response of liver, kidney, and heart was delayed and involved fewer genes, but revealed a dominant genetic program that was seen in all 6 tissues. Many of the 85 uniquely annotated transcripts participating in this shared genomic response have not been previously linked to SEB. Nine of the 85 genes were subsequently confirmed by RT-PCR in every tissue/organ at 24 h. These 85 transcripts, up-regulated in all tissues, annotated to the interferon (IFN)/antiviral-response and included genes belonging to the DNA/RNA sensing system, DNA damage repair, the immunoproteasome, and the ER/metabolic stress-response and apoptosis pathways. Overall, this shared program was identified as a type I and II interferon (IFN)-response and the promoters of these genes were highly enriched for IFN regulatory matrices. Several genes whose secreted products induce the IFN pathway were up-regulated at early time points in PBMCs, spleen, and/or lung. Furthermore, IFN regulatory factors including Irf1, Irf7 and Irf8, and Zbp1, a DNA sensor/transcription factor that can directly elicit an IFN innate immune response, participated in this host-wide SEB signature.

Conclusion

Global gene-expression changes across multiple organs implicated a host-wide IFN-response in SEB-induced death. Therapies aimed at IFN-associated innate immunity may improve outcome in toxic shock syndromes.

HCV-induced miR-21 contributes to evasion of host immune system by targeting MyD88 and IRAK1

Upon recognition of viral components by pattern recognition receptors, such as the toll-like receptors (TLRs) and retinoic acid-inducible gene I (RIG-I)-like helicases, cells are activated to produce type I interferon (IFN) and proinflammatory cytokines. These pathways are tightly regulated by the host to prevent an inappropriate cellular response, but viruses can modulate these pathways to proliferate and spread. In this study, we revealed a novel mechanism in which hepatitis C virus (HCV) evades the immune surveillance system to proliferate by activating microRNA-21 (miR-21). We demonstrated that HCV infection upregulates miR-21, which in turn suppresses HCV-triggered type I IFN production, thus promoting HCV replication. Furthermore, we demonstrated that miR-21 targets two important factors in the TLR signaling pathway, myeloid differentiation factor 88 (MyD88) and interleukin-1 receptor-associated kinase 1 (IRAK1), which are involved in HCV-induced type I IFN production. HCV-mediated activation of miR-21 expression requires viral proteins and several signaling components. Moreover, we identified a transcription factor, activating protein-1 (AP-1), which is partly responsible for miR-21 induction in response to HCV infection through PKCε/JNK/c-Jun and PKCα/ERK/c-Fos cascades. Taken together, our results indicate that miR-21 is upregulated during HCV infection and negatively regulates IFN-α signaling through MyD88 and IRAK1 and may be a potential therapeutic target for antiviral intervention.

Hepatitis C virus (HCV), a major cause of chronic hepatitis, end-stage cirrhosis, and hepatocellular carcinoma, has chronically infected 200 million people worldwide and 3–4 million more each year. When triggered by viral infection, host cells produce type I interferon (IFN) and proinflammatory cytokines to antagonize the virus. Despite extensive research, the mechanism underlying HCV immune system evasion remains elusive. Our results provided the first direct evidence that microRNA-21 (miR-21) feedback inhibits type I IFN signaling when cells are challenged with HCV, thus promoting the infection. MicroRNA is a kind of endogenous non-coding small RNA that regulates a wide range of biological processes and participate in innate and adaptive immune responses through complementarily pairing with target mRNA, which can regulate its expression or translation. Currently, miRNAs have intrigued many scientists as potent targets or therapeutic agents for diseases. In our study, the targets of miR-21, myeloid differentiation factor 88 (MyD88) and interleukin-1 receptor-associated kinase 1 (IRAK1), which are important for HCV-induced type I IFN production, have also been found. Moreover, we identified a transcription factor, AP-1, which is partly responsible for miR-21 induction in response to HCV infection. Taken together, our research has provided new insights into understanding the effects of miRNA on host-virus interactions, and revealed a potential therapeutic target for antiviral intervention.

A single nucleotide polymorphism in inflammatory gene RNASEL predicts outcome after radiation therapy for localized prostate cancer

PURPOSE

To study associations between single nucleotide polymorphisms (SNP) in Ribonuclease L (RNASEL), a gene implicated in inflammation and prostate cancer risk, and outcomes after radiation therapy.

EXPERIMENTAL DESIGN

We followed participants in the prospective US Health Professionals Follow-Up Study treated with radiation therapy for early-stage prostate cancer. Three SNPs were genotyped based on previously determined functional and biological significance. We used multivariable Cox proportional hazards models to assess per-allele associations with the primary outcome defined as time to a composite endpoint including development of lethal prostate cancer or biochemical recurrence.

RESULTS

We followed 434 patients treated with radiation therapy for a median of 9 years. On multivariate analysis, the rs12757998 variant allele was associated with significantly decreased risk of the composite endpoint [HR: 0.65; 95% confidence interval (CI), 0.45-0.94%; P = 0.02] driven by decreased biochemical recurrence (HR: 0.60; 95% CI, 0.40-0.89%; P = 0.01) and men treated with external beam (HR: 0.58; 95% CI, 0.36-0.93%; P = 0.02). In contrast, in 516 men from the same cohort treated with radical prostatectomy, we found no significant impact of this variant on outcome. Furthermore, the rs12757998 variant allele significantly modified the association between androgen deprivation therapy and outcomes after radiation therapy (p-interaction = 0.02).

CONCLUSION

We show an association between RNASEL SNP rs12757998 and outcome after radiation therapy for prostate cancer. This SNP is associated with increased circulating C-reactive protein and interleukin-6, suggesting a potential role for inflammation in the response to radiation. If validated, genetic predictors of outcome may help inform prostate cancer management.

Identification and functional characterization of tRNA-derived RNA fragments (tRFs) in respiratory syncytial virus infection

The discovery of small noncoding RNAs (sncRNAs) with regulatory functions is a recent breakthrough in biology. Among sncRNAs, microRNA (miRNA), derived from host or virus, has emerged as elements with high importance in control of viral replication and host responses. However, the expression pattern and functional aspects of other types of sncRNAs, following viral infection, are unexplored. In order to define expression patterns of sncRNAs, as well as to discover novel regulatory sncRNAs in response to viral infection, we applied deep sequencing to cells infected with human respiratory syncytial virus (RSV), the most common cause of bronchiolitis and pneumonia in babies. RSV infection leads to abundant production of transfer RNA (tRNA)-derived RNA Fragments (tRFs) that are ~30 nucleotides (nts) long and correspond to the 5'-half of mature tRNAs. At least one tRF, which is derived from tRNA-Glu-CTC, represses target mRNA in the cytoplasm and promotes RSV replication. This demonstrates that this tRF is not a random by-product of tRNA degradation but a functional molecule. The biogenesis of this tRF is also specific, as it is mediated by the endonuclease angiogenin (ANG), not by other nucleases. In summary, our study presents novel information on the induction of a functional tRF by viral infection.

Inflammatory gene variants and the risk of biliary tract cancers and stones: a population-based study in China

Background

Genetic variants in inflammation-related genes have been associated with biliary stones and biliary tract cancers in previous studies.

Methods

To follow-up on these findings, we examined 35 single nucleotide polymorphism (SNPs) in 5 genes related to inflammation (IL8, NFKBIL, RNASEL, TNF, and VEGFA) in 456 participants with incident biliary tract cancer cases (262 gallbladder, 141 extrahepatic bile duct, 53 ampulla of Vater), 982 participants with biliary stones, and 860 healthy controls in a population–based case–control study in Shanghai, China.

Results

Suggestive associations were observed for SNPs in VEGFA with biliary stones, IL8 with gallbladder and ampulla of Vater cancers, and RNASEL with ampulla of Vater cancer (false discovery rate≤0.2).

Conclusion

These findings provide additional support for the role of inflammation in biliary stones and biliary tract cancer risk and need further validation.

Characterization of human phosphodiesterase 12 and identification of a novel 2'-5' oligoadenylate nuclease - The ectonucleotide pyrophosphatase/phosphodiesterase 1

The vertebrate 2-5A system is part of the innate immune response and central to cellular antiviral activities. Upon activation by viral double-stranded RNA, 5'-triphosphorylated, 2'-5'-linked oligoadenylate polyribonucleotides (2-5As) are synthesized by one of several 2'-5' oligoadenylate synthetases. The 2-5As bind and activate RNase L, an unspecific endoribonuclease, resulting in viral and cellular RNA decay. Given that most endogenous RNAs are degraded by RNase L, continued enzyme activity will eventually lead to cell growth arrest and cell death. This is averted, when 2-5As and their 5'-dephosphorylated forms, the so-called 2-5A core molecules, are cleaved and thus inactivated by 2'-5'-specific nuclease(s), e.g. phosphodiesterase 12, thereby turning RNase L into its latent form. In this study, we have characterized the human phosphodiesterase 12 in vitro focusing on its ability to degrade 2-5As and 2-5A core molecules. We have found that the enzyme activity is distributive and is influenced by temperature, pH and divalent cations. This allowed us to determine V(max) and K(m) kinetic parameters for the enzyme. We have also identified a novel 2'-5'-oligoadenylate nuclease; the human plasma membrane-bound ectonucleotide pyrophosphatase/phosphodiesterase 1, suggesting that 2-5A catabolism may be a multienzyme-regulated process.

Hepatitis B virus induces a novel inflammation network involving three inflammatory factors, IL-29, IL-8, and cyclooxygenase-2

Chronic inflammation induced by hepatitis B virus (HBV) is a major causative factor associated with the development of cirrhosis and hepatocellular carcinoma. In this study, we investigated the roles of three inflammatory factors, IL-8, IL-29 (or IFN-λ1), and cyclooxygenase-2 (COX-2), in HBV infection. We showed that the expression of IL-29, IL-8, and COX-2 genes was enhanced in HBV-infected patients or in HBV-expressing cells. In HBV-transfected human lymphocytes and hepatocytes, IL-29 activates the production of IL-8, which in turn enhances the expression of COX-2. In addition, COX-2 decreases the production of IL-8, which in turn attenuates the expression of IL-29. Thus, we proposed that HBV infection induces a novel inflammation cytokine network involving three inflammatory factors that regulate each other in the order IL-29/IL-8/COX-2, which involves positive regulation and negative feedback. In addition, we also demonstrated that COX-2 expression activated by IL-8 was mediated through CREB and C/EBP, which maintains the inflammatory environment associated with HBV infection. Finally, we showed that the ERK and the JNK signaling pathways were cooperatively involved in the regulation of COX-2. We also demonstrated that IL-29 inhibits HBV replication and that IL-8 attenuates the expression of IL-10R2 and the anti-HBV activity of IL-29, which favors the establishment of persistent viral infection. These new findings provide insights for our understanding of the mechanism by which inflammatory factors regulate each other in response to HBV infection.

Immune activation and target organ damage are consequences of hydrodynamic treatment but not delivery of naked siRNAs in mice

Short-interfering RNAs (siRNAs), key mediators of RNA interference comprise a promising therapeutic tool, although side effects such as interferon (IFN) response are still not perfectly understood. Further, delivery to target organs is a major challenge, possibly associated with side effects including immune activation or organ damage. We investigated whether immune activation as a consequence of double-stranded RNA induced IFN response (Jak/STAT pathway activation or cytokine production) or target organ damage is induced by in vivo low-volume (LV) or high-volume (HV) hydrodynamic delivery or treatment with naked siRNA. NMRI mice were injected with naked siRNAs or saline by hydrodynamic injection (HDI) and positive control mice received polyinosinic-polycytidilic acid (poly I:C). LV (1 mL/mouse) and HV (10% of body weight) HDI were compared. After LV HDI, STAT1 and OAS1 gene expression inflammatory cytokine plasma levels and target organ injury were assessed. LV HDI induced slight alanine aminotransferase elevation and mild hepatocyte injury, whereas HV HDI resulted in high ALAT level and extensive hepatocyte necrosis. STAT1 or OAS1 was not induced by LV siRNA; however, HV saline led to a time-dependent slight increase in gene expression. Inflammatory cytokine plasma level and organ histology and functional parameters demonstrated no damage following LV HDI with or without siRNA. Our data demonstrate that naked siRNAs may be harnessed, without the induction of IFN response or immune activation, and that LV HDI is preferable, because HV HDI may cause organ damage.

Arg462Gln and Asp541Glu polymorphisms in ribonuclease L and prostate cancer risk: a meta-analysis

Objective

The association between ribonuclease L (RNASEL) gene polymorphisms and prostate cancer risk has been widely reported, but the results of these studies remained controversial and underpowered. We performed a meta-analysis of 28 studies to evaluate the association between Arg462Gln and Asp541Glu polymorphisms in the RNASEL gene and prostate cancer risk.

Methods

Odds ratios (ORs) with 95% confidence intervals (CIs) were estimated to assess the association between RNASEL polymorphisms and prostate cancer risk.

Results

A significantly increased prostate cancer risk was found for the Arg462Gln polymorphism in Africans (Gln/Gln vs Arg/Arg: OR = 2.50, 95%CI = 1.28-4.87; Gln/Gln vs Gln/Arg + Arg/Arg: OR = 2.54, 95%CI = 1.30-4.95), but not in Europeans and Asians. Additionally, the Asp541Glu polymorphism was associated with increased total prostate cancer risk (Glu-allele vs Asp-allele: OR = 1.04, 95%CI = 1.01-1.07; Glu/Glu vs Asp/Asp: OR = 1.22, 95%CI = 1.03-1.46; Glu/Glu vs Glu/Asp + Asp/Asp: OR = 1.09, 95%CI = 1.02-1.16). In the stratified analysis for the Asp541Glu polymorphism, there was a significantly increased prostate cancer risk in Africans and Europeans, and in hospital-based prostate cancer cases.

Conclusion

The meta-analysis results showed evidence that RNASEL Arg462Gln and Asp541Glu polymorphisms are associated with prostate cancer risk and could be low-penetrance prostate cancer susceptibility biomarkers.

Identification of cellular genes induced in human cells after activation of the OAS/RNaseL pathway by vaccinia virus recombinants expressing these antiviral enzymes

Interferon (IFN) type I induces the expression of antiviral proteins such as 2',5'-oligoadenylate synthetases (OAS). The enzyme OAS is activated by dsRNA to produce 5'-phosphorylated, 2-5-linked oligoadenylates (2-5A) that activate RNaseL which, in turn, triggers RNA breakdown, leading to multiple biological functions. Although RNaseL is required for IFN antiviral function, there are many aspects of the molecular mechanisms that remain obscure. Here, we have used microarray analyses from human HeLa cells infected with vaccinia virus (VACV) recombinants expressing OAS-RNaseL enzymes (referred as 2-5A system) with the aim to identify host genes that are up- or down-regulated in the course of infection by the activation of this antiviral pathway. We found that activation of the 2-5A system from VACV recombinants produces a remarkable stimulation of transcription for genes that regulate many cellular processes, like those that promote cell growth arrest, GADD45B and KCTD11, apoptosis as CUL2, PDCD6, and TNFAIP8L2, IFN-stimulated genes as IFI6, and related to tumor suppression as PLA2G2A. The 2-5A system activation produces down-regulation of transcription of some genes that promote cell growth as RUNX2 and ESR2 and of genes in charge to maintain mitochondria homeostasis as MIPEP and COX5A. These results reveal new genes induced in response to the activation of the 2-5A system with roles in apoptosis, translational control, cell growth arrest, and tumor suppression.

Polymorphism of OAS-1 determines liver fibrosis progression in hepatitis C by reduced ability to inhibit viral replication

BACKGROUND

Progression of disease after hepatitis C virus (HCV) infection differs among individuals, indicating a possibility of participation of host genetic factors. 2'-5'-oligoadenylate synthetase 1 (OAS-1), an important component of the innate immune system, has an antiviral function, and may therefore have a certain relationship with progression of disease.

AIM

To evaluate single nucleotide polymorphisms (SNPs) of OAS-1 and its relationship with the disease status of HCV infection.

METHODS

Six SNPs of OAS-1 were selected and examined in 409 Japanese patients with chronic HCV infection using the TaqMan PCR genotyping method. The relationship of SNP genotypes and clinical manifestations of patients was analysed. Then, a pair of OAS-1-expression plasmids mimicking the clinical-related SNPs were created and transfected into liver cells carrying the HCV subgenomic replicon or the full-length genome, JFH1, and HCV replication after transfection was compared.

RESULTS

Patients with genotypes A/A, A/G and G/G of an SNP of OAS-1 at the exon 3 of its coding sequence were at gradient increased risks of suffering from higher serum alanine aminotransferase (P<0.001) and aspartate aminotransferase (P=0.001), higher degree of liver fibrosis (P=0.010) and higher presence of liver cirrhosis (P=0.001). By multivariate logistic regression analysis, genotype G/G was an independent factor associated with cirrhosis (P=0.013, odds ratio 3.11, 95% confidence interval 1.27-7.63). In liver cells, OAS-1 with the G allele showed lower ability to inhibit virus replication than OAS-1 with the A allele (P=0.004).

CONCLUSIONS

The SNP of OAS-1 at the exon 3 of its coding sequence was associated with progression of disease in Japanese patients with HCV infection.

Combination chemotherapy employing bispecific antisense oligonucleotides having binding sites directed against an autocrine regulated growth pathway and bcl-2 for the treatment of prostate tumors

In previous studies we demonstrated that antisense oligonucleotides (oligos) against transforming growth factor-alpha (TGF-alpha [MR1]), its binding site the epidermal growth factor receptor (EGFR [MR2]), and the anti-apoptosis protein bcl-2 (MR4) are efficacious against prostate tumors. In recent reports we also describe how two of these mRNA directed binding sites can be synthesized sequentially within a single linear complementary strand and administered either in the presence or absence of additional therapeutic agents. In these continuing experiments "bispecific" oligo pairs were further evaluated in the presence or absence of Cytoxan, Taxol, or DES. One oligo pair recognized the binding sites for TGF-alpha and EGFR mRNA (TGF-alpha/EGFR [MR12] and EGFR/TGF-alpha [MR21]); another pair recognized binding sites for EGFR and bcl-2 (EGFR/bcl-2 [MR24] and bcl-2/EGFR [MR42]). Oligo pairs differ in their linear 5' to 3' binding site orientations, and were tested in vitro against PC-3 and LNCaP prostate tumor cell lines. Following cell attachment, incubations were for 2 days with the agents followed by 2 days in their absence. When tested against PC-3 cells and combined with LD50 Cytoxan, MR2, MR4, MR24, MR42 significantly inhibited 47.3, 45.7, 68.3, and 64.9%; with LD50 Taxol MR2, MR4, MR24, MR42 significantly inhibited 49.8, 45.8, 64.1, and 59.2%; and with LD50 DES MR2, MR4, MR24, MR42 significantly inhibited 66.6, 67.6, 64.3, and 67.2% respectively. Each agent significantly increased the inhibition produced by either oligo alone.LNCaP cells were also incubated with mono- and bispecific oligos in either the presence or absence of chemotherapeutics. MR2, MR4, MR24, MR42 produced significant inhibitions of 57.4, 58.4, 69.4, and 68.6% with LD50 Cytoxan; 70.4, 70.1, 73.6, and 74.0% with LD50 Taxol; and 49.8, 50.1, 59.6, and 53.9%, respectively with LD50 DES.A complete PC-3 experiment compared MR1, MR2, MR4, MR12, MR21, MR24 and MR42, in the presence of LD50 Cytoxan. Each oligo combined with Cytoxan significantly inhibited: MR1 by 51.0, MR2 by 55.0, MR4 by 58.0; MR12 by 56.0; MR21 by 61.1, MR24 by 65.5 and MR42 by 66.0%. Bispecifics directed against two different pathways, MR24, and MR42 were the most effective.A complete LNCaP experiment compared the same series of oligos also in the presence of LD50 Cytoxan. Each oligo combined with Cytoxan significantly inhibited: MR1 by 49.0, MR2 by 50.0, MR4 by 53.0; MR12 by 52.0; MR21 by 58.6, MR24 by 53.9 and MR42 by 58.0%.

Physiology and molecular biology of petal senescence

Petal senescence is reviewed, with the main emphasis on gene expression in relation to physiological functions. Autophagy seems to be the major mechanism for large-scale degradation of macromolecules, but it is still unclear if it contributes to cell death. Depending on the species, petal senescence is controlled by ethylene or is independent of this hormone. EIN3-like (EIL) transcription factors are crucial in ethylene-regulated senescence. The presence of adequate sugar levels in the cell delays senescence and prevents an increase in the levels of EIL mRNA and the subsequent up-regulation of numerous senescence-associated genes. A range of other transcription factors and regulators are differentially expressed in ethylene-sensitive and ethylene-insensitive petal senescence. Ethylene-independent senescence is often delayed by cytokinins, but it is still unknown whether these are natural regulators. A role for caspase-like enzymes or metacaspases has as yet not been established in petal senescence, and a role for proteins released by organelles such as the mitochondrion has not been shown. The synthesis of sugars, amino acids, and fatty acids, and the degradation of nucleic acids, proteins, lipids, fatty acids, and cell wall components are discussed. It is claimed that there is not enough experimental support for the widely held view that a gradual increase in cell leakiness, resulting from gradual plasma membrane degradation, is an important event in petal senescence. Rather, rupture of the vacuolar membrane and subsequent rapid, complete degradation of the plasma membrane seems to occur. This review recommends that more detailed analysis be carried out at the level of cells and organelles rather than at that of whole petals.

Association of RNASEL variants with prostate cancer risk in Hispanic Caucasians and African Americans

PURPOSE

The RNASEL gene at 1q25 has been identified as a hereditary prostate cancer susceptibility gene, but to date, no study has investigated the role of RNASEL variants in Hispanic Caucasian men with prostate cancer.

EXPERIMENTAL DESIGN

Two RNASEL common variants, located at amino acids 462 and 541, were genotyped in non-Hispanic Caucasian, Hispanic Caucasian, and African American prostate cancer cases and controls.

RESULTS

The RNASEL 462 AA genotype was found to increase prostate cancer risk over 4-fold in Hispanic Caucasians [odds ratio (OR), 4.43; 95% confidence interval (95% CI), 1.68-11.68; P = 0.003] and over 10-fold in African Americans (OR, 10.41; 95% CI, 2.62-41.40; P = 0.001) when compared with the GG genotype. Analysis of the RNASEL 541 variant showed that Hispanic Caucasian patients with the GG genotype had a statistically significant increase in their risk for developing prostate cancer when compared with the TT and GT genotypes (OR, 1.91; 95% CI, 1.16-3.14; P = 0.01). A common G-T haplotype for the combination of the RNASEL 462 and 541 variants was found to occur more frequently in controls compared with cases in African Americans (P = 0.04) but not in non-Hispanic Caucasians or Hispanic Caucasians.

CONCLUSIONS

This is the first study that investigates the association of prostate cancer risk with RNASEL variants in Hispanic men. Our data support the role of RNASEL as a predisposition gene for prostate cancer and showed a significant association between the RNASEL 462 variant and prostate cancer risk in African Americans and Hispanic Caucasians.

Treatment of MCF-7 breast cancer cells employing mono- and bispecific antisense oligonucleotides having binding specificity toward proteins associated with autocrine regulated growth and BCL-2

Antisense oligonucleotides (oligos) against transforming growth factor-alpha (TGF-alpha) (MR1) and its binding site, the epidermal growth factor receptor (EGFR) (MR2), are efficacious against the UACC 897 breast, PC-3 and LNCaP prostate, and T98G glioblastoma tumor lines in both in vitro and in vivo studies. Oligos against the anti-apoptosis protein bcl-2 (MR4) are also efficient against PC-3 and LNCaP tumors in similar in vitro experiments. To enhance activity, and also to introduce a derivative type of multifunctional oligo into this field, "bispecifics" were constructed containing two truncated complementary DNA sequences (from either MR1 or MR2) designed to bind targeted mRNA about their respective AUG initiation codons, and/or a similar sequence adjacent to the AUG site of mRNA encoding bcl-2. Tandem pairs of bispecifics were constructed: The first had complementary sequences for TGF-alpha and EGFR mRNA, but differed in 5' to 3' tandem orientation (TGF-alpha/EGFR [MR12] and EGFR/TGF-alpha [MR21] sequences); a second pair had binding sites associated with EGFR and bcl-2, also differing in orientation (EGFR/bcl-2 [MR24] and bcl-2/EGFR [MR42]). In studies targeting PC-3 and LNCaP cells, bispecifics demonstrated significant in vitro activity, and the second pair was significantly better than the original monospecifics. These studies are now extended to the MCF-7 breast cancer model in order to determine whether these particular bispecifics have similar anti-breast cancer activity and if they are significantly better than monospecific oligos from which they were derived. We conclude that bispecific oligos significantly inhibit MCF-7 growth, however, in contrast to results obtained with PC-3 and LNCaP, the monospecific oligos directed against EGFR and bcl-2 have significantly greater activity than the bispecifics targeting a combination of TGF-alpha, EGFR, or bcl-2. These data suggest that the relative activities of oligos, whether mono- or bispecific, change with tumor type. Bispecific oligos which target different proteins, possibly those which regulate estrogen utilization, may be more effective against MCF-7 cells and warrant additional investigation, particularly if co-administered with traditional chemotherapeutics.

Transcriptional activation of interferon-stimulated genes but not of cytokine genes after primary infection of rhesus macaques with dengue virus type 1

Macaques are the only animal model used to test dengue virus (DENV) vaccine candidates. Nevertheless, the pathogenesis of DENV in macaques is not well understood. In this work, by using Affymetrix oligonucleotide microarrays, we studied the broad transcriptional modifications and cytokine expression profile after infecting rhesus macaques with DENV serotype 1. Five days after infection, these animals produced a potent, innate antiviral immune response by inducing the transcription of signature genes from the interferon (IFN) pathway with demonstrated antiviral activity, such as myxoprotein, 2',5'-oligoadenylate synthetase, phospholipid scramblase 1, and viperin. Also, IFN regulatory element 7, IFN-stimulated gene 15, and protein ligases linked to the ISGylation process were up-regulated. Unexpectedly, no up-regulation of IFN-alpha, -beta, or -gamma genes was detected. Transcription of the genes of interleukin-10 (IL-10), IL-8, IL-6, and tumor necrosis factor alpha was neither up-regulated nor down-regulated. Results were confirmed by real-time PCR and by multiplex cytokine detection in serum samples.

ICP0 prevents RNase L-independent rRNA cleavage in herpes simplex virus type 1-infected cells

The classical interferon (IFN)-dependent antiviral response to viral infection involves the regulation of IFN-stimulated genes (ISGs), one being the gene encoding cellular endoribonuclease RNase L, which arrests protein synthesis and induces apoptosis by nonspecifically cleaving rRNA. Recently, the herpes simplex virus type 1 (HSV-1) protein ICP0 has been shown to block the induction of ISGs by subverting the IFN pathway upstream of the 2'-5'-oligoadenylate synthetase (OAS)/RNase L pathway. We report that ICP0 also prevents rRNA degradation at late stages of HSV-1 infection, independent of its E3 ubiquitin ligase activity, and that the resultant rRNA degradation is independent of the classical RNase L antiviral pathway. Moreover, the degradation is independent of the viral RNase vhs and is independent of IFN response factor 3. These studies indicate the existence of another, previously unidentified, RNase that is part of the host antiviral response to viral infection.

Inhibition of HIV type 1 replication in CD4+ and CD14+ cells purified from HIV type 1-infected individuals by the 2-5A agonist immunomodulator, 2-5A(N6B)

Two major interferon (IFN)-mediated antiviral defense enzymes are double-stranded (ds)RNA-dependent 2',5'-oligoadenylate (2-5A) synthetase (2-5OAS) and p68 kinase (PKR). When activated by dsRNA, 2-5OAS synthesizes 2-5A, which binds to and activates RNase L. Activated RNase L hydrolyzes single-stranded viral RNA, thereby inhibiting viral protein synthesis. HIV-1 inhibits the IFN-mediated intracellular antiviral pathways. We have reported the synthesis and characterization of a nuclease-resistant 2-5A agonist (2-5A(N6B)) that overcomes the HIV-1 induced blockades by restoring the 2-5OAS/RNase L antiviral pathway (Homan JW, et al., J Acquir Immune Defic Syndr 2002;30:9-20). The objective of this study was to test the effect of 2-5A(N6B) on chronically infected CD4(+) T lymphocytes and CD14(+) monocytes derived from HIV-1-seropositive individuals. Wild-type HIV-1 replication was effectively inhibited by 2-5A(N6B) in CD4(+) T lymphocytes and CD14(+) monocytes purified from HIV-1 seropositive individuals (n = 18) compared to untreated cells. We also assessed the cytotoxicity of 2-5A(N6B) and report that 2-5A(N6B) exerts its anti-HIV-1 activity with no evidence of cytotoxicity (IC(90) > 100,000 nM). Furthermore, 2-5A(N6B) did not alter the cellular RNA profile, affect CCR5 or CXCR4 coreceptor expression, or activate caspase-dependent apoptosis. Evidence is also provided to show that 2-5A(N6B), and naturally occurring 2-5A(4), act as ligands to activate human Toll-like receptor 4. These results indicate that the 2-5A agonist 2-5A(N6B) has the potential to enhance host cell innate and acquired immune defense mechanisms against HIV-1 infection.

Transcriptional profiles of chicken embryo cell cultures following infection with infectious bursal disease virus

Infectious bursal disease virus (IBDV) is the causative agent of infectious bursal disease in chickens and causes a significant economic loss for the poultry industry. Little is understood about the mechanism involved in the host responses to IBDV infection. For better understanding the IBDV-host interaction, we measured steady-state levels of transcripts from 28 cellular genes of chicken embryo (CE) cell cultures infected with IBDV vaccine stain Bursine-2 during a 7-day infection course by use of the quantitative real-time RT-PCR SYBR green method. Of the genes tested, 21 genes (IRF-1, IFN 1-2 promoter, IFNAR-1, IRF-10, IFN-gamma, 2',5'-OAS, IAP-1, caspase 8, TRAIL-like, STAT-3, IL-6, IL-8, MIP-3 alpha, MHC-I, MHC-II, TVB, GLVR-1, OTF, IL-13R alpha, ST3GAL-VI and PGK) showed an increased expression. The remaining seven genes (IFNAR-2, IFN-alpha, NF-kappaB subunit p65, BLRcp38, DDX1, G6PDH and UB) showed a constant expression or only slight alteration. Apparently, the host genes involved in pro-inflammatory response and apoptosis, interferon-regulated proteins, and the cellular immune response were affected by IBDV infection, indicating involvement in the complex signaling pathways of host responses to the infection. This study thus contributes to the understanding of the pathogenesis of IBD and provides an insight into the virus-host interaction.

The double-stranded RNA-induced apoptosis pathway is involved in the cytopathogenicity of cytopathogenic Bovine viral diarrhea virus

Bovine viral diarrhea virus (BVDV), which is classified in the genus Pestivirus, family Flaviviridae, can be divided into two biotypes according to its ability to induce a cytopathic effect in tissue culture cells. The mechanisms through which cytopathogenic (cp) BVDV induces cell death and non-cytopathogenic (ncp) BVDV causes persistent infection without producing cell death remain unclear. Here, it was found that the overexpression of four apoptosis-related cellular mRNAs in cells infected with cpBVDV could also be caused by synthetic dsRNA. In fact, it was found that the amount of dsRNA produced by cpBVDV considerably exceeded the amount yielded by ncpBVDV. To evaluate the possible involvement of dsRNA in the induction of apoptosis, this study examined whether RNAi-mediated depletion of two dsRNA-reactive cellular factors, dsRNA-dependent protein kinase and 2′,5′-oligoadenylate synthetase 1, resulted in the prevention of cpBVDV-induced apoptosis. Although the induction of apoptosis was reduced after the suppression of either factor alone, the simultaneous silencing of both factors resulted in an almost complete inhibition of apoptosis without affecting viral titre. These results showed that dsRNA is the main trigger of apoptosis in cpBVDV-infected cells and that the cytopathogenicity of BVDV depends on the yield potential of dsRNA. In contrast, ncpBVDV yielded minimal levels of dsRNA, thereby establishing a persistent infection without inducing apoptosis. This report supports the significance of viral dsRNA as a trigger of innate immune responses.

Cracking the egg: molecular dynamics and evolutionary aspects of the transition from the fully grown oocyte to embryo

Fully grown oocytes (FGOs) contain all the necessary transcripts to activate molecular pathways underlying the oocyte-to-embryo transition (OET). To elucidate this critical period of development, an extensive survey of the FGO transcriptome was performed by analyzing 19,000 expressed sequence tags of the Mus musculus FGO cDNA library. Expression of 5400 genes and transposable elements is reported. For a majority of genes expressed in mouse FGOs, homologs transcribed in eggs of Xenopus laevis or Ciona intestinalis were found, pinpointing evolutionary conservation of most regulatory cascades underlying the OET in chordates. A large proportion of identified genes belongs to several gene families with oocyte-restricted expression, a likely result of lineage-specific genomic duplications. Gene loss by mutation and expression in female germline of retrotransposed genes specific to M. musculus is documented. These findings indicate rapid diversification of genes involved in female reproduction. Comparison of the FGO and two-cell embryo transcriptomes demarcated the processes important for oogenesis from those involved in OET and identified novel motifs in maternal mRNAs associated with transcript stability. Discovery of oocyte-specific eukaryotic translation initiation factor 4E distinguishes a novel system of translational regulation. These results implicate conserved pathways underlying transition from oogenesis to initiation of development and illustrate how genes acquire and lose reproductive functions during evolution, a potential mechanism for reproductive isolation.

Role of mitochondria in apoptosis induced by the 2-5A system and mechanisms involved

The 2-5A system (2-5OAS/RNaseL) is composed of the 2',5'oligoadenylate synthetase 1 (2-5OAS1) and 2-5A-dependent RNase (RNaseL), enzymes that play a key role in antiviral defence mechanisms. Activation of the 2-5A system by double stranded RNA (dsRNA) induces degradation of ribosomal RNAs and apoptosis in mammalian cells. To obtain further information into the molecular mechanisms by which RNaseL induces apoptosis, we expressed human RNaseL and 2-5OAS in HeLa cells using recombinant vaccinia viruses as vectors and we analysed in detail different biochemical markers of apoptosis. In this expression virus-cell system the activation of RNaseL, as index of rRNA degradation, is an upstream event of apoptosis induction. RNaseL induces apoptosis in a caspase-dependent manner (caspases 8, 9 and 2). At the beginning of apoptosis RNaseL and 2-5OAS are localized in the mitochondria and cytosol fractions, while at the onset of apoptosis both enzymes are largely in mitochondria. The 2-5A system induces the release of Cytochrome c from mitochondria to cytosol in a caspase dependent manner. The onset of apoptosis elicits the disruption of mitochondrial membrane potential (delta psi m), as well as the generation of reactive oxygen species (ROS). Moreover, the activation of RNaseL induces morphological alterations in the mitochondria. Apoptosis induced by the 2-5A system involves mitochondrial proteins, such as the human anti-apoptotic protein Bcl-2, which blocks both the apoptosis and the change of delta psi m induced by the activation of RNaseL. These findings provide new insights into the molecular mechanisms of apoptosis induction by the 2-5A system, demonstrating the importance of mitochondria in 2-5OAS/RNaseL-induced apoptosis.

Decreased expression of eukaryotic initiation factor 3f deregulates translation and apoptosis in tumor cells

The eukaryotic initiation factor 3f (eIF3f) is the p47 subunit of the multi-subunit eIF3 complex. eIF3 plays an important role in translation initiation. In the present study, we investigate the biological function of eIF3f in translation and apoptosis in tumor cells. We demonstrated for the first time that eIF3f is downregulated in most human tumors using a cancer profiling array and confirmed by real-time reverse transcription PCR in melanoma and pancreatic cancer. Overexpression of eIF3f inhibits cell proliferation and induces apoptosis in melanoma and pancreatic cancer cells. Silencing of eIF3f protects melanoma cells from apoptosis. We further investigated the biological function of eIF3f. In vitro translation studies indicate that eIF3f is a negative regulator of translation and that the region between amino acids 170 and 248 of eIF3f is required for its translation regulatory function. Ectopic expression of eIF3f inhibits translation and overall cellular protein synthesis. Ribosome profile and ribosomal RNA (rRNA) fragmentation assays revealed that eIF3f reduces ribosomes, which may be associated with rRNA degradation. We propose that eIF3f may play a role in ribosome degradation during apoptosis. These data provide critical insights into the cellular function of eIF3f and in linking translation initiation and apoptosis.

Vaccination with a Sindbis virus-based DNA vaccine expressing antigen 85B induces protective immunity against Mycobacterium tuberculosis

To improve DNA vaccination against Mycobacterium tuberculosis, we evaluated the effectiveness of a Sindbis virus-based DNA construct expressing the tuberculosis antigen 85B (Sin85B). The protective efficacy of Sin85B was initially assessed by aerogenically challenging immunized C57BL/6 mice with virulent Mycobacterium tuberculosis. At 1 and 7 months postinfection, the lung bacterial burdens were considerably reduced and the lung pathology was improved in vaccinated mice compared to naive controls. Furthermore, the mean survival period for Sin85B-immunized mice (305 +/- 9 days) after the tuberculous challenge was extended 102 days relative to the naive mice (203 +/- 13 days) and was essentially equivalent to the survival time of Mycobacterium bovis BCG-vaccinated mice (294 +/- 15 days). The essential role of gamma interferon (IFN-gamma) in Sin85B-mediated protection was established by showing that significantly increased levels of IFN-gamma mRNA were present postinfection in lung cells from vaccinated mice relative to control mice and by demonstrating that IFN-gamma depletion prior to challenge abolished the vaccine-induced protection. The substantial antituberculosis protective responses induced by Sin85B immunization of CD4-/- mice strongly suggested that CD8 cells partially mediate Sin85B-induced protective immunity. Interestingly, Sin85B vaccination did not protect RNase L-/- (a key enzyme in the innate antiviral response) mice while significant protection was detected in RNase L-/- mice immunized with either BCG or a conventional DNA plasmid expressing antigen 85B. These data show that immunization with Sin85B offers protection similar to BCG in a murine model of pulmonary tuberculosis and suggest that Sin85B-induced protection is dependent upon both innate and acquired immune mechanisms.

Rhinovirus induces airway epithelial gene expression through double-stranded RNA and IFN-dependent pathways

Rhinovirus (RV) infection is the major cause of common colds and of asthma exacerbations. Because the epithelial cell layer is the primary target of RV infection, we hypothesize that RV-induced airway disease is associated with the perturbation of airway epithelial gene expression. In this study, well differentiated primary human airway epithelial cells were infected with either RV16 (major group) or RV1B (minor group). Transcriptional gene profiles from RV-infected and mock-infected control cells were analyzed by Affymetrix Genechip, and changes of the gene expression were confirmed by real-time RT-PCR analysis. At 24 h after infection, 48 genes induced by both viruses were identified. Most of these genes are related to the IFN pathway, and have been documented to have antiviral functions. Indeed, a significant stimulation of IFN-beta secretion was detected after RV16 infection. Neutralizing antibody specific to IFN-beta and a specific inhibitor of the Janus kinase pathway both significantly blocked the induction of RV-inducible genes. Further studies demonstrated that 2-aminopurine, a specific inhibitor double-stranded RNA-dependent protein kinase, could block both IFN-beta production and RV-induced gene expression. Thus, IFN-beta-dependent pathway is a part of the double-stranded RNA-initiated pathway that is responsible for RV-induced gene expression. Consistent with its indispensable role in the induction of antiviral genes, deactivation of this signaling pathway significantly enhanced viral production. Because increase of viral yield is associated with the severity of RV-induced airway illness, the discovery of an epithelial antiviral signaling pathway in this study will contribute to our understanding of the pathogenesis of RV-induced colds and asthma exacerbations.

Critical role for the oligoadenylate synthetase/RNase L pathway in response to IFN-beta during acute ocular herpes simplex virus type 1 infection

We previously demonstrated that IFN-beta transgene treatment protects mouse trigeminal ganglia (TG) cells from acute HSV-1 infection in vitro. However, IFN-alpha6 transgene treatment does not provide protection against acute HSV-1 infection in vitro, even though equivalent levels of IFN are expressed with both transgene treatments. In the present study we show that IFN-beta transgene treatment before acute ocular HSV-1 infection protects mice from HSV-1-mediated mortality, whereas IFN-alpha6 transgene treatment does not reduce mortality. Treatment with the IFN-beta and IFN-alpha6 transgenes was associated with increased expression of oligoadenylate synthetase (OAS)1a mRNA in the eye. However, protein kinase R mRNA was not up-regulated in the eye. In TG, only IFN-beta transgene treatment reduced infectious virus levels. Furthermore, in the absence of a functional OAS pathway, corneal HSV-1 Ag expression was more widespread, and the ability of IFN-beta transgene treatment to reduce infectious HSV-1 in eyes and TG was lost. Along with selective up-regulation of OAS1a mRNA expression in TG from IFN-beta transgene-treated mice, we found increased levels of phospho-STAT1. Likewise, p38 MAPK phosphorylation was increased in TG from IFN-beta transgene-treated mice, compared with both IFN-alpha6 and vector-treated mice. We also observed a time-dependent increase in JNK phosphorylation in TG from IFN-beta transgene-treated vs IFN-alpha6 and vector-treated mice. Our results demonstrate that IFN-beta is a potent antiviral cytokine that exerts protection against ocular HSV-1 infection via selective up-regulation of OAS1a mRNA in TG and by altering the phosphorylation of proteins in antiviral signaling cascades.

Mapping of candidate tumor suppressor genes on chromosome 12 in adenoid cystic carcinoma

Adenoid cystic carcinoma (ACC) is a common malignancy of salivary glands, for which the underlying genetic mechanisms of tumorigenesis are poorly understood. Prior studies in ACC have identified deletions in chromosome 12. To further characterize these changes, we performed an extensive LOH analysis in 58 ACC using a panel of 28 microsatellite markers. Results show 66% overall genetic loss. Three markers (D12S1713, D12S2196, D12S398) are contiguous and define a 6.84 Mb region of deletion at 12q13.11-q13.13. Two other markers (D12S2078, D12S1628) are also contiguous and define a 4.5 Mb region of deletion at 12q24.32-q24.33. The three remaining markers, D12S1056 at 12q14.1, D12S1051 at 12q23.1 and D12S1636 at 12q23.3 define smaller regions of deletion. An analysis of microarray gene expression profiling data available for ACC shows several genes with significant transcriptional downregulation that map to these areas of genetic deletion. This combined genetic and genomic analysis provides several candidate genes to test for functional tumor suppressor activity in ACC.

Involvement of Noxa in Cellular Apoptotic Responses to Interferon, Double-stranded RNA, and Virus Infection

Double-stranded RNA (dsRNA) accumulates in virally infected cells, leading to induction of genes encoding proteins involved in signaling, apoptosis, protein synthesis/processing, and cell metabolism. Noxa is a BH3-containing mitochondrial protein that contributes to apoptosis by disrupting mitochondrial outer membrane integrity. Here we demonstrate potent induction of Noxa expression by exposure of cells to dsRNA, interferon (IFN), and virus. Noxa induction was confirmed by using reverse transcriptase-PCR and immunoblot analyses in multiple human tumor cell lines. Importantly, Noxa regulation by IFN and dsRNA was independent of p53, thereby identifying a novel mechanism of Noxa induction. Ectopic expression of Noxa in HT1080 fibrosarcoma cells enhanced cellular sensitivity to viral or dsRNA/actinomycin D-induced apoptosis, typified by enhanced cytochrome c release from the mitochondrial to the cytosolic fraction and increased cleavage of caspases 3 and 9. Point and deletion mutations of Noxa confirmed that both the BH3 domain and the mitochondrial-targeting domain were necessary for enhanced cellular apoptotic responses to dsRNA, IFN, or virus. Treatment of cells with dsRNA or virus, but not etoposide, induced interaction between Noxa and Bax that required an intact Noxa BH3 domain. Interestingly, the Noxa mitochondrial-targeting domain deletion mutant interacted with Bax in a dsRNA-dependent manner and redirected Bax away from the mitochondria, thus acting as a dominant-negative protein. Together, these data suggest that Noxa is an important component of the innate immune response of cells to viral infection, leading to enhanced cellular apoptosis that may play a role in limiting viral dissemination.

ER stress and the unfolded protein response

Conformational diseases are caused by mutations altering the folding pathway or final conformation of a protein. Many conformational diseases are caused by mutations in secretory proteins and reach from metabolic diseases, e.g. diabetes, to developmental and neurological diseases, e.g. Alzheimer's disease. Expression of mutant proteins disrupts protein folding in the endoplasmic reticulum (ER), causes ER stress, and activates a signaling network called the unfolded protein response (UPR). The UPR increases the biosynthetic capacity of the secretory pathway through upregulation of ER chaperone and foldase expression. In addition, the UPR decreases the biosynthetic burden of the secretory pathway by downregulating expression of genes encoding secreted proteins. Here we review our current understanding of how an unfolded protein signal is generated, sensed, transmitted across the ER membrane, and how downstream events in this stress response are regulated. We propose a model in which the activity of UPR signaling pathways reflects the biosynthetic activity of the ER. We summarize data that shows that this information is integrated into control of cellular events, which were previously not considered to be under control of ER signaling pathways, e.g. execution of differentiation and starvation programs.

Poliovirus, pathogenesis of poliomyelitis, and apoptosis

Poliovirus (PV) is the causal agent of paralytic poliomyelitis, an acute disease of the central nervous system (CNS) resulting in flaccid paralysis. The development of new animal and cell models has allowed the key steps of the pathogenesis of poliomyelitis to be investigated at the molecular level. In particular, it has been shown that PV-induced apoptosis is an important component of the tissue injury in the CNS of infected mice, which leads to paralysis. In this review the molecular biology of PV and the pathogenesis of poliomyelitis are briefly described, and then several models of PV-induced apoptosis are considered; the role of the cellular receptor of PV, CD155, in the modulation of apoptosis is also addressed.

Two mechanisms of caspase 9 processing in double-stranded RNA- and virus-triggered apoptosis

Viral double-stranded RNA (dsRNA) is a ubiquitous intracellular "alert signal" used by cells to detect viral infection and to mount anti-viral responses. DsRNA triggers a rapid (complete within 2-4 h) apoptosis in the highly-susceptible HeLa cell line. Here, we demonstrate that the apical event in this apoptotic cascade is the activation of procaspase 8. Downstream of caspase 8, the apoptotic signaling cascade bifurcates into a mitochondria-independent caspase 8/caspase 3 arm and a mitochondria-dependent, caspase 8/Bid/Bax/Bak/cytochrome c arm. Both arms impinge upon, and activate, procaspase 9 via two different cleavage sites within the procaspase 9 molecule (D330 and D315, respectively). This is the first in vivo demonstration that the "effector" caspase 3 plays an "initiator" role in the regulation of caspase 9. The dsRNA-induced apoptosis is potentiated by the inhibition of protein synthesis, whose role is to accelerate the execution of all apoptosis steps downstream of, and including, the activation of caspase 8. Thus, efficient apoptosis in response to viral dsRNA results from the co-operation of the two major apical caspases (8 and 9) and the dsRNA-activated protein kinase R (PKR)/ribonuclease L (RNase L) system that is essential for the inhibition of protein synthesis in response to viral infection.

Predominant contribution of IFN-beta expression to apoptosis induction in human uterine cervical fibroblast cells by influenza-virus infection

We have been investigating an apoptosis induction in human fetal membrane cells by influenza virus (IV) infection and the contribution of apoptosis induction to the viral infection-defense response between a fetus and the maternal body. For studying any role of uterine cells in the anti-viral response, we investigated the molecular mechanism of the apoptotic induction in human uterine cervical fibroblast cell line (HCF) by IV infection. IV type A and B infection induced DNA fragmentation in HCF. In IV-infected HCF, gene mRNA expression levels of interleukine (IL)-1beta, IL-6, tumor necrosis factor (TNF) alpha, Fas ligand, interferon regulatory factor (IRF)-1, interferon (IFN) alpha and IFN beta increased as compared with those in mock treatment cells, and the induction of mRNAs for double stranded RNA dependent protein kinase (PKR), indolamine 2,3-deoxygenase (IDO) and 2'-5' oligoadenylate synthetase (2-5 OAS) were indicated, which had a role for a host defense response induced by IFN-beta. The amount of IFN-beta protein increased by IV-infection, and DNA fragmentation was inhibited with anti-IFN-beta antibody and PKR inhibitor (2-aminopurine). Furthermore, a synthetic double stranded RNA, poly I : C, could induce almost the same phenomena as that induced by virus infection. We conclude that IV-infection induces the apoptosis in HCF cells through the IFN-beta expression regulated by double stranded RNA and IRF-1 induction, and suggest that the IFN-beta induction may be the predominant contribution to the IV infection induced HCF apoptosis.

Identification of 2'-phosphodiesterase, which plays a role in the 2-5A system regulated by interferon

The 2-5A system is one of the major pathways for antiviral and antitumor functions that can be induced by interferons (IFNs). The 2-5A system is modulated by 5'-triphosphorylated, 2',5'-phosphodiester-linked oligoadenylates (2-5A), which are synthesized by 2',5'-oligoadenylate synthetases (2',5'-OASs), inactivated by 5'-phosphatase and completely degraded by 2'-phosphodiesterase (2'-PDE). Generated 2-5A activates 2-5A-dependent endoribonuclease, RNase L, which induces RNA degradation in cells and finally apoptosis. Although 2',5'-OASs and RNase L have been molecularly cloned and studied well, the identification of 2'-PDE has remained elusive. Here, we describe the first identification of 2'-PDE, the third key enzyme of the 2-5A system. We found a putative 2'-PDE band on SDS-PAGE by successive six-step chromatographies from ammonium sulfate precipitates of bovine liver and identified a partial amino acid sequence of the human 2'-PDE by mass spectrometry. Based on the full-length sequence of the human 2'-PDE obtained by in silico expressed sequence tag assembly, the gene was cloned by reverse transcription-PCR. The recombinant human 2'-PDE expressed in mammalian cells certainly cleaved the 2',5'-phosphodiester bond of 2-5A trimer and 2-5A analogs. Because no sequences with high homology to this human 2'-PDE were found, the human 2'-PDE was considered to be a unique enzyme without isoform. Suppression of 2'-PDE by a small interfering RNA and a 2'-PDE inhibitor resulted in significant reduction of viral replication, whereas overexpression of 2'-PDE protected cells from IFN-induced antiproliferative activity. These observations identify 2'-PDE as a key regulator of the 2-5A system and as a potential novel target for antiviral and antitumor treatments.

Activation of airway epithelial cells by toll-like receptor agonists

Toll-like receptors (TLR) play an important role in pathogen recognition and innate immunity. We investigated the presence and function of TLRs in the BEAS-2B airway epithelial cell line and primary bronchial epithelial cells. Standard real-time reverse transcriptase-polymerase chain reaction (RT-PCR) analysis and Taqman RT-PCR revealed that BEAS-2B cells express mRNA for TLR1-10. Several TLR ligands were tested for their ability to activate gene expression in BEAS-2B cells using limited microarray analyses focusing on genes of the chemokine and chemokine receptor family, cytokines, and signaling pathways. While the TLR3 ligand double-stranded RNA was the most effective epithelial activator, clear responses to flagellin, lipopolysaccharide, CpG, peptidoglycan, and zymosan were also observed. RT-PCR and/or enzyme-linked immunosorbent assay were used to confirm results obtained with microarrays for five of the induced genes: interleukin-8, serum amyloid A, TLR3, macrophage inflammatory protein-3alpha, and granulocyte-macrophage colony-stimulating factor. Stimulation of epithelial cells with double-stranded RNA induced levels of interleukin-8 exceeding 20 ng/ml and levels of serum amyloid A exceeding 80 ng/ml. Double-stranded RNA, lipopolysaccharide, zymosan A, and flagellin also induced expression of macrophage inflammatory protein-3alpha and granulocyte-macrophage colony-stimulating factor, which may facilitate immature dendritic cell migration and maturation. These results suggest that airway epithelial cells express several TLRs and that they are functionally active. Epithelial expression of TLRs may be of importance in inflammation and immunity in the airways in response to inhaled pathogens.

IFN-alpha sensitizes human umbilical vein endothelial cells to apoptosis induced by double-stranded RNA

The ability of endothelial cells to mount an efficient antiviral response is important in restricting viral dissemination and eliminating viral infection from the endothelium and surrounding tissues. We demonstrate that dsRNA, a molecular signature of viral infection, induced apoptosis in HUVEC, and priming with IFN-alpha shortened the time between when dsRNA was encountered and when apoptosis was initiated. IFN-alpha priming induced higher levels of mRNA for dsRNA-activated protein kinase, 2'5'-oligoadenylate synthetase, and Toll-like receptor 3, transcripts that encode dsRNA-responsive proteins. dsRNA induced activation of dsRNA-activated protein kinase and nuclear translocation of transcription factors RelA and IFN regulatory factor-3 in IFN-alpha-primed HUVECs before the activation of intrinsic and extrinsic apoptotic pathways. These changes did not occur in the absence of dsRNA, and apoptosis resulting from incubation with dsRNA occurred much later when cells were not primed with IFN-alpha. The entire population of IFN-alpha-primed HUVECs underwent nuclear translocation of RelA and IFN regulatory factor-3 in response to dsRNA, whereas less than one-half of the population responded with apoptosis. When IFN-alpha-primed HUVECs were coincubated with dsRNA and proteasome inhibitors, all HUVECs were rendered susceptible to dsRNA-induced apoptosis. These studies provide evidence that many endothelial cells that are alerted to the risk of infection by IFN-alpha would undergo apoptosis sooner in response to dsRNA than non-IFN-alpha-primed cells, and this would enhance the likelihood of eliminating infected cells prior to the production of progeny virions.

Hypermethylation of the 5' CpG island of the FHIT gene is associated with hyperdiploid and translocation-negative subtypes of pediatric leukemia

The human FHIT (fragile histidine triad) gene is a putative tumor suppressor gene located at chromosome region 3p14.2. Previous studies have shown that loss of heterozygosity, homozygous deletions, and abnormal expression of the FHIT gene are involved in several types of human malignancies. A CpG island is present in the 5' promoter region of the FHIT gene, and methylation in this region correlates with loss of FHIT expression. To test whether aberrant methylation of the FHIT gene may play a role in pediatric leukemia, we assessed the FHIT methylation status of 10 leukemia cell lines and 190 incident population-based cases of childhood acute lymphocytic and myeloid leukemias using methylation-specific PCR. Conventional and fluorescence in situ hybridization cytogenetic data were also collected to examine aneuploidy, t(12, 21), and other chromosomal rearrangements. Four of 10 leukemia cell lines (40%) and 52 of 190 (27.4%) bone marrows from childhood leukemia patients demonstrated hypermethylation of the promoter region of FHIT. Gene expression analyses and 5-aza-2'-deoxycytidine treatment showed that promoter hypermethylation correlated with FHIT inactivation. Among primary leukemias, hypermethylation of FHIT was strongly correlated with acute lymphoblastic leukemia (ALL) histology (P = 0.008), high hyperdiploid (P < 0.0001), and translocation-negative (P < 0.0001) categories. Hyperdiploid B-cell ALLs were 23-fold more likely to be FHIT methylated compared with B-cell ALL harboring TEL-AML translocations. FHIT methylation was associated with high WBC counts at diagnosis, a known prognostic indicator. These results suggest that hypermethylation of the promoter region CpG island of the FHIT gene is a common event and may play an important role in the etiology and pathophysiology of specific cytogenetic subtypes of childhood ALL.