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

ArticleinThe Journal of Immunology 174(3):1171-7 · March 2005with14 Reads
DOI: 10.4049/jimmunol.174.3.1171 · Source: PubMed
Abstract
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.

Figures

Figure
Figure
Figure
    • "Indeed, many viruses antagonize RNase L and its effects. For example, encephalomyocarditis virus (EMCV) (Zhou, 1993 ), herpes simplex virus-1 (HSV- 1) (Austin, 2005; Zheng, 2001), vaccinia virus (VV) (Diaz-Guerra, 1997), coxsackie B4 virus (Flodstrom-Tullberg, 2005), West Nile virus (), Theiler's virus (TMEV) (), and Coronaviruses (Cruz, 2011;) inhibit antiviral activity of the OAS-RNase L pathway by expressing antagonizing proteins that are in some cases vital for viral replication and pathogenesis (). One of the most common and well-characterized mechanisms of IFN antagonism is the binding and sequestering of dsRNA by proteins such as VV pE3L (Chang et al., 1992; Xiang et al., 2002), influenza virus NS1 (Lu et al., 1995; Min and Krug, 2006), reovirus σ3, and HSV-1 pUS11 (Schneider, 2003). "
    [Show abstract] [Hide abstract] ABSTRACT: Murine hepatitis virus (MHV) infection activates the potent antiviral oligoadenylate synthetase-endoribonuclease latent (OAS-RNase L) pathway in myeloid-derived cells of the liver and brain but not in other cell types in these organs. Canonically, it is thought that upregulation of Oas transcription by type I interferon (IFN) during virus infection is needed to activate the pathway. However, MHV induces IFN and upregulate OASs only late in infection, after RNase L has already been activated. The objective of this thesis work was to determine what role interferon and OAS play in RNase L activation. For this purpose, bone marrow derived macrophages (BMM) were used that were either fully competent to respond to and secrete IFN (WT B6), unable to secrete IFN (Ifih1-/-), or not capable of IFN signaling (Ifnar1-/-). It was found that basal mRNA expression levels of Oas1a, Oas2, and Oas3 in na�ve mice were significantly higher in the liver than in the brain and in myeloid-derived versus non-myeloid derived cells. Furthermore, activation of RNase L did not require virus-induced IFN, but rather correlated with adequate levels of basal Oas gene and protein expression, maintained by basal IFN signaling. This suggests that basal levels of OAS might influence the host’s ability to activate RNase L and restrict MHV infection in an organ-specific and cell type-specific manner. Data herein demonstrate that myeloid cells are pre-armed with high basal levels of OAS, sufficient to allow activation of RNase L upon sensing dsRNA early in infection before interferon signaling develops. This limits virus replication and spread, thus sparing non-myeloid neighboring cells from infection. Together, these studies have helped define the increasingly complex interactions between MHV and the type I IFN response.
    Article · Jan 2016 · Endocrine Pathology
    Lester Dillon Birdwell
    • "Immunostaining with clone 5D8/1 (Dako, Glostrup, Denmark) to detect enterovirus capsid protein 1 (VP1) in cells was performed as previously described [18]. For murine tissue, FFPE pancreatic sections were cut into 5-m sections and stained as previously described [19], with the following modifications; antigen retrieval 9 nt, nucleotide. 10 AP, alkaline phosphatase. "
    [Show abstract] [Hide abstract] ABSTRACT: Enteroviral infections are common, affecting humans across all age groups. RT-PCR is widely used to detect these viruses in clinical samples. However, there is a need for sensitive and specific in situ detection methods for formalin-fixed tissues, allowing for the anatomical localization of the virus and identification of its serotype. The aim was to design novel enterovirus probes, assess the impact of probe design for the detection and optimize the new single molecule in situ hybridization technology for the detection of enteroviruses in formalin-fixed paraffin-embedded samples. Four enterovirus RNA-targeted oligonucleotide RNA probes - two probes for wide range enterovirus detection and two for serotype-targeted detection of Coxsackievirus B1 (CVB1) - were designed and validated for the commercially available QuantiGene ViewRNA in situ hybridization method. The probe specificities were tested using a panel of cell lines infected with different enterovirus serotypes and CVB infected mouse pancreata. The two widely reactive probe sets recognized 19 and 20 of the 20 enterovirus serotypes tested, as well as 27 and 31 of the 31 CVB1 strains tested. The two CVB1 specific probe sets detected 30 and 14 of the 31 CVB1 strains, with only minor cross-reactivity to other serotypes. Similar results were observed in stained tissues from CVB -infected mice. These novel in-house designed probe sets enable the detection of enteroviruses from formalin-fixed tissue samples. Optimization of probe sequences makes it possible to tailor the assay for the detection of enteroviruses on the serotype or species level. Copyright © 2015 Elsevier B.V. All rights reserved.
    Full-text · Article · Jun 2015
    • "This has been confirmed in both the UK and nPOD cohorts [57]. It has been shown by others that PKR is both induced and activated following an enteroviral infection and that this leads to phosphorylation of an eukaryotic initiation factor, eIF2alpha, involved in protein synthesis [60, 61]. This causes translational arrest and, as such, will result in the selective depletion of the more labile proteins. "
    [Show abstract] [Hide abstract] ABSTRACT: Type 1 diabetes is a multifactorial disease resulting from a complex interplay between host genetics, the immune system and the environment, that culminates in the destruction of insulin-producing beta cells. The incidence of type 1 diabetes is increasing at an alarming rate, especially in children under the age of 5 (Gepts in Diabetes 14(10):619-613, 1965; Foulis et al. in Lancet 29(5):267-274, 1986; Gamble, Taylor and Cumming in British Medical Journal 4(5887):260-262 1973). Genetic predisposition, although clearly important, cannot explain this rise, and so, it has been proposed that changes in the 'environment' and/or changes in 'how we respond to our environment' must contribute to this rising incidence. In order to gain an improved understanding of the factors influencing the disease process, it is important, firstly, to focus on the organ at the centre of the illness-the pancreas. This review summarises our knowledge of the pathology of the endocrine pancreas in human type 1 diabetes and, in particular, explores the progression of this understanding over the past 25 years.
    Article · Feb 2014
Show more