The study of antiviral pathways to reveal methods for the effective response and clearance of virus is closely related to understanding interferon (IFN) signaling and its downstream target genes, IFN-stimulated genes. One of the key antiviral factors induced by IFNs, 2'-5' oligoadenylate synthase (OAS), is a well-known molecule that regulates the early phase of viral infection by degrading viral RNA in combination with RNase L, resulting in the inhibition of viral replication. In this review, we describe OAS family proteins from a different point of view from that of previous reviews. We discuss not only RNase L-dependent (canonical) and -independent (noncanonical) pathways but also the possibility of the OAS family members as biomarkers for various diseases and clues to non-immunological functions based on recent studies. In particular, we focus on OASL, a member of the OAS family that is relatively less well understood than the other members. We will explain its anti- and pro-viral dual roles as well as the diseases related to single-nucleotide polymorphisms in the corresponding gene.
2',5'-Oligoadenylate Synthetase/*genetics/*metabolism ; Animals ; Biomarkers ; *Disease Susceptibility ; Endoribonucleases/metabolism ; Genetic Predisposition to Disease ; Humans ; Multigene Family ; Polymorphism, Single Nucleotide ; Signal Transduction

OBJECTIVETo investigate the association between the genetic polymorphism of 2',5'-oligoadenylate synthetase 1 (OAS1) and susceptibility to spontaneous preterm birth (SPTB) and preterm premature rupture of membranes (PPROM).

METHODSThe case-control study consisted of 599 preterm infants including 171 cases of PPROM, and 673 full-term infants without maternal histories of SPTB and PPROM as controls. The single nucleotide polymorphism (SNP) at OAS1 intron 5, rs10774671, was analyzed by polymerase chain reaction-restriction fragment length polymorphism.

RESULTSNo significant differences were observed between the case and control groups in the frequencies of genotypes (AA, GA, and GG) and alleles (A and G) of OAS1 rs10774671. When the case group was divided into two subgroups with or without PPROM, no significant differences in the genotype and allele frequencies were found between each subgroup and the control group. When the case group was divided into three subgroups with different gestational ages at SPTB, no significant differences in the genotype and allele frequencies were detected between each subgroup and the control group.

CONCLUSIONSNo association is identified between OAS1 SNP and susceptibility to SPTB and PPROM.

2',5'-Oligoadenylate Synthetase ; genetics ; Adult ; Case-Control Studies ; Female ; Fetal Membranes, Premature Rupture ; genetics ; Genetic Predisposition to Disease ; Humans ; Infant, Newborn ; Male ; Polymorphism, Single Nucleotide ; Premature Birth ; genetics

In this study, we examined the expression of Toll-like receptor3 (TLR3) by human retinal pigment epithelial cells (RPE) and determined whether exposure to the TLR3 agonist polyinosinic-polycytidylic acid (poly I:C) would induced the expression of cytokines in these cells. RT-PCR revealed that TLR3 was constitutively expressed in human RPE, and its expression was increased by treatment with poly I:C. After treatment with poly I:C, we determined the expression levels of pro-inflammatory cytokines in human RPE using RT-PCR and ELISA. We demonstrated that poly I:C treatment increased the production of TNF-alpha, IL-6, and IL-8 in human RPE. Upon exposure to poly I:C, human RPE initiated antiviral response resulting in the induction of IFN-beta mRNA expression and 2',5'-oligoadenylate synthetase mRNA expression. These results suggest that human RPE may participate in ocular defense mechanism against viral infection through TLR3.
2',5'-Oligoadenylate Synthetase ; Cytokines* ; Enzyme-Linked Immunosorbent Assay ; Epithelial Cells* ; Humans* ; Interferons ; Interleukin-6 ; Interleukin-8 ; Poly I-C ; Retinal Pigment Epithelium ; Retinaldehyde* ; RNA, Messenger ; Tumor Necrosis Factor-alpha

2',5'-Oligoadenylate Synthetase ; genetics ; Adult ; Carrier State ; virology ; Case-Control Studies ; Female ; Hepatitis B ; drug therapy ; genetics ; virology ; Hepatitis B virus ; Humans ; Interferon-alpha ; therapeutic use ; Male ; Middle Aged ; Polyethylene Glycols ; therapeutic use ; Polymorphism, Genetic ; Recombinant Proteins

OBJECTIVETo investigate the possible influence of HBV and its antigens on the expressions of JAK-STAT signal transduction pathway molecules and the antiviral proteins of IFN alpha.

METHODSThe HepG2 cells were transfected with pSM2, pHBS2-S and pHBc-EGFP plasmids which express HBV whole particles or S-antigen, Pre-S antigen and core antigens. The infectious supernatant from HepG2.2.15 cells and the pured HBV proteins which contained the S, Pre-S antigens were used to treat the HepG2 cells. Northern blot and RT-PCR were applied to analyse the expressions of the antiviral proteins MxA, 2' -5' OAS, 9-27 and the JAK-STAT signal transduction pathway molecules STAT1 in HepG2 cells responded to the IFN alpha treatment.

RESULTSThe HepG2 cells transfected with pSM2, pHBS2-S and pHBc-EGFP plasmids could express whole HBV particles and HBsAg, Pre-S antigen and HBcAg. The quantitation of expressed HBV particles and antigens increased significantly during the course of transfection. Northern blot hybridization analysis indicated that the HepG2 cells expressed IFN alpha antiviral proteins MxA, 2' -5' OAS and 9-27. When transfected with pHBV-dimer, pHBS2-S, pHBc-EGFP plasmids, the IFN/A antiviral proteins MxA, 2' -5' OAS and 9-27 in transfected cells were reduced greatly as compared to the un-transfected HepG2 cells, and the expressed antiviral proteins decreased sharply with the development of transfection time. Furthermore, the expression of IFN alpha JAK-STAT signal transduction pathway molecule STAT1 was also inhibited with the expression of HBV particles and HBV antigens in transfected HepG2 cells.

CONCLUSIONSThe HBV and its antigens influence the expressions of IFN alpha JAK-STAT signal transduction pathway molecules and antiviral proteins in the hepatocellular models in vitro. It is indicated that HBV might possess the activity to antagonise or counteract the IFN alpha antiviral action.

2',5'-Oligoadenylate Synthetase ; metabolism ; GTP-Binding Proteins ; metabolism ; Hep G2 Cells ; Hepatitis B Antigens ; immunology ; Hepatitis B virus ; immunology ; Humans ; Interferon-alpha ; metabolism ; Myxovirus Resistance Proteins ; RNA-Binding Proteins ; metabolism ; STAT1 Transcription Factor ; metabolism ; Signal Transduction ; Transfection

Toll-like receptor 5 (TLR5) is responsible for the recognition of bacterial flagellin in vertebrates. In the present study, the first TLR5 gene in duck was cloned. The open reading frame (ORF) of duck TLR5 (dTLR5) cDNA is 2580 bp and encodes a polypeptide of 859 amino acids. We also cloned partial sequences of myeloid differentiation factor 88, 2'-5'-oligoadenylate synthetase (OAS), and myxovirus resistance (Mx) genes from duck. dTLR5 mRNA was highly expressed in the bursa of Fabricius, spleen, trachea, lung, jejunum, rectum, and skin; moderately expressed in the muscular and glandular tissues, duodenum, ileum, caecum, and pancreas; and minimally expressed in the heart, liver, kidney, and muscle. DF-1 or HeLa cells transfected with DNA constructs encoding dTLR5 can activate NF-kappaB leading to the activation of interleukin-6 (IL-6) promoter. When we challenged ducks with a Herts33 Newcastle disease virus (NDV), mRNA transcription of the antiviral molecules Mx, Double stranded RNA activated protein kinase (PKR), and OAS was up-regulated in the liver, lung, and spleen 1 and 2 days post-inoculation.
2',5'-Oligoadenylate Synthetase/genetics/metabolism ; Animals ; Cell Line ; *Cloning, Molecular ; Ducks ; Gene Expression Regulation/*physiology ; Humans ; Immunity, Innate ; Myeloid Differentiation Factor 88/genetics/metabolism ; Myxovirus Resistance Proteins/genetics/metabolism ; Newcastle Disease/metabolism ; Newcastle disease virus/classification ; RNA, Messenger/genetics/metabolism ; Species Specificity ; Toll-Like Receptor 5/genetics/*metabolism

To study the effect of HCV core protein on the interferon-induced antiviral genes expression and its mechanisms. Methods HepG2 cells were transiently transfected with HCV core protein expression plasmid and the blank plasmid respectively. RT-PCR was used to analyze the effect of HCV core protein on PKR and 2'-5'OAS expression. The effect of HCV core protein on ISRE-medicated gene expression was detected by luciferase activity assay. Western-blot assay was performed to observe the change of mRNA and protein levels of SOCS3, STAT1 and p-STAT1 following HCV core expression. In the presence of HCV core protein, the transcription of PKR and 2'-5' OAS are down-regulated. ISRE-medicated reporter gene expression and STAT1 phosphorylation were inhibited. The transcription and expression of SOCS3 were induced compared with blank plasmid-transfected group. In HepG2 cells, HCV core protein can down-regulate the expression of some interferon-induced antiviral genes, which involves the induction of SOCS3 and the inhibition of STAT1 phosphorylation.
2',5'-Oligoadenylate Synthetase ; genetics ; metabolism ; Carcinoma, Hepatocellular ; pathology ; Down-Regulation ; Hepacivirus ; genetics ; metabolism ; Humans ; Interferon-Stimulated Gene Factor 3 ; genetics ; metabolism ; Interferon-alpha ; genetics ; immunology ; Liver Neoplasms ; pathology ; Protein Kinases ; genetics ; metabolism ; STAT1 Transcription Factor ; genetics ; metabolism ; STAT2 Transcription Factor ; genetics ; metabolism ; Transcription, Genetic ; Transfection ; Tumor Cells, Cultured ; Viral Core Proteins ; genetics ; metabolism ; physiology