RNase L and Double-Stranded RNA-Dependent Protein Kinase Exert Complementary Roles in Islet Cell Defense during Coxsackievirus Infection

Department of Immunology, IMM-23, The Scripps Research Institute, La Jolla, CA 92037, USA.
The Journal of Immunology (Impact Factor: 4.92). 03/2005; 174(3):1171-7. DOI: 10.4049/jimmunol.174.3.1171
Source: PubMed


Coxsackievirus (CV) is an important human pathogen that has been linked to the development of autoimmunity. An intact pancreatic beta cell IFN response is critical for islet cell survival and protection from type 1 diabetes following CV infection. In this study, we show that IFNs trigger an antiviral state in beta cells by inducing the expression of proteins involved in intracellular antiviral defense. Specifically, we demonstrate that 2',5'-oligoadenylate synthetases (2-5AS), RNase L, and dsRNA-dependent protein kinase (PKR) are expressed by pancreatic islet cells and that IFNs (IFN-alpha and IFN-gamma) increase the expression of 2-5AS and PKR, but not RNase L. Moreover, our in vitro studies uncovered that these pathways play important roles in providing unique and complementary antiviral activities that critically regulate the outcome of CV infection. The 2-5AS/RNase L pathway was critical for IFN-alpha-mediated islet cell resistance from CV serotype B4 (CVB4) infection and replication, whereas an intact PKR pathway was required for efficient IFN-gamma-mediated repression of CVB4 infection and replication. Finally, we show that the 2-5AS/RNase L and the PKR pathways play important roles for host survival during a challenge with CVB4. In conclusion, this study has dissected the pathways used by distinct antiviral signals and linked their expression to defense against CVB4.

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    • "HP68 was initially identified as the RNase L inhibitor (RLI) (Bisbal et al., 1995). RNase L is an effector enzyme of the cellular system that utilizes 2′,5′-linked oligoadenylates as a major regulator, which is involved in the interferon-induced antiviral and antiproliferative response (Bisbal et al., 2001; Bisbal and Silverman, 2007; Flodstrom-Tullberg et al., 2005; Silverman, 1994). Upregulation of the RLI expression by viruses, including HIV-1 (Martinand et al., 1999), suggests that HP68/RLI may have a two-fold positive effect on HIV-1 replication ; first, as a host factor essential for capsid assembly, and second, as a negative regulator of the antiviral enzyme RNase L. "
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    ABSTRACT: TULA, a recently identified UBA- and SH3-containing protein, has previously been shown to regulate cell signaling through protein tyrosine kinases. In order to search for novel functions of TULA, we identified, using mass spectrometry, proteins associated with TULA. ABCE-1 also known as RLI and HP68, a host factor of HIV-1 assembly, was found among TULA-associated proteins in these experiments. Considering an important role of ABCE-1 in HIV-1 assembly, we were compelled to analyze the effect of TULA on HIV-1 biogenesis. Our study provides evidence that TULA proteins substantially inhibit production of both sub-genomic and full-length HIV-1 viral particles and that the effect of TULA is dependent on UBA domain-mediated interactions. The primary role of ABCE-1 in the effect of TULA appears to be the recruitment of TULA to the sites of HIV-1 assembly where TULA interferes with the late steps of the HIV-1 life cycle, most likely by disrupting essential ubiquitylation-dependent events that remain to be identified.
    Virology 04/2008; 372(1):10-23. DOI:10.1016/j.virol.2007.10.012 · 3.32 Impact Factor
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    • "The OAS/RNase L pathway is required for a complete innate antiviral response. Accordingly, mice lacking RNase L have a reduced ability to survive infections by any one of several different types of viruses, including Coxsackievirus B4, encephalomyocarditis virus and West Nile virus (14–16). Although transient activation of RNase L is compatible with cell survival, sustained activation is not (17–20). "
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    ABSTRACT: The antiviral and antitumor functions of RNase L are enabled by binding to the allosteric effectors 5'-phosphorylated, 2',5'-linked oligoadenylates (2-5A). 2-5A is produced by interferon-inducible 2',5'-oligoadenylate synthetases (OAS) upon activation by viral double-stranded RNA (dsRNA). Because mutations in RNase L have been implicated as risk factors for prostate cancer, we sought to determine if OAS activators are present in prostate cancer cells. We show that prostate cancer cell lines (PC3, LNCaP and DU145), but not normal prostate epithelial cells (PrEC), contain RNA fractions capable of binding to and activating OAS. To identify the RNA activators, we developed a cDNA cloning strategy based on stringent affinity of RNAs for OAS. We thus identified mRNAs for Raf kinase inhibitor protein (RKIP) and poly(rC)-binding protein 2 (PCBP2) that bind and potently activate OAS. In addition, human endogenous retrovirus (hERV) envelope RNAs were present in PC3 cells that bind and activate OAS. Analysis of several gene expression profiling studies indicated that PCBP2 RNA was consistently elevated in metastatic prostate cancer. Results suggest that OAS activation may occur in prostate cancer cells in vivo stimulated by cellular mRNAs for RKIP and PCBP2.
    Nucleic Acids Research 02/2006; 34(22):6684-95. DOI:10.1093/nar/gkl968 · 9.11 Impact Factor
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    ABSTRACT: We have studied the innate immune responses of Atlantic salmon and how this responds to stimulation and infection by the aquatic orthomyxovirus Infectious salmon anemia virus (ISAV). This work has focused on the Type I interferon (IFN) system which is critically important in the vertebrate immune response against viral infections. As a part of this work we have studied the Atlantic salmon IFN regulatory factor 7 (IRF7). In mammals IRF7 is the major regulator of IFN transcription in response to viral infections, and our results show that the salmon homolog performs similar tasks. Furthermore, we have investigated the stimulatory effect of two synthetic ligands that induce the IFN system by mimicking viral infections in the cell and compared this to the immune response against ISAV. Our results indicate that both specialized immune cells and non-immune cells induce the IFN system in response to these treatments, but we also show that ISAV is able to interfere with the host` IFN response in order to successfully replicate. Finally, our studies show that the ISAV genome encodes two genes, S7ORF1 and S8ORF2, which is involved in antagonizing the IFN response during infections. The papers of the thesis are not available in Munin: 1. Kileng, Ø., Brundtland, M. I. and Robertsen, B.: «Infectious salmon anemia virus is a powerful inducer of key genes of the type I interferon system of Atlantic salmon, but is not inhibited by interferon», Fish & Shellfish immunology 23(2007); 378-389 (Elsevier - publisher's restriction). Available at 2. Kileng, Ø., Albuquerque, A. and Robertsen, B.: «Induction of interferon system genes in Atlantic salmon by the imidazoquinoline S-27609, a ligand for Toll-like receptor 7», Fish & Shellfish immunology 24(2007); 514-522 (Elsevier - publisher's restriction). Available at 3. García-Rosado, E., Markussen, T., Kileng, Ø., Baekkevold, E. S., Robertsen, B., Mjaaland, S. and Rimstad, E.: «Molecular and functional characterization of two infectious salmon anaemia virus (ISAV) proteins with type I interferon antagonizing activity», Virus Research 133(2008); 228-238 (Elsevier - publisher's restriction). Available at 4. Kileng, Ø., Workenhe, S. T., Bergan, V. and Robertsen, B.: «An Atlantic salmon IRF-7 gene identified by analysis of sequence and function and its expression compared with a STAT1 gene». Manuscript, later published in Developmental and Comparative Immunology 33(2009); 18-27 (Elsevier), published version available at
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