Ribosomal RNA cleavage, nuclease activation and 2-5A (ppp(A2′p)<sub>n</sub>A) in interferon-treated cells

Wreschner, Daniel H.; James, Tharappel C.; Silverman, Robert H.; Kerr, Ian M.

doi:10.1093/nar/9.7.1571

Cited by 248 publications

(167 citation statements)

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“…The model system for these early studies involved IFN treatment of mouse L fibroblasts followed by infections with the picornavirus, encephalomyocarditis virus (EMCV). Detection of activated RNase L within cells could be conveniently monitored by the specific breakdown in the rRNA [44]. By demonstrating IFNand virus-dependent activation of both OAS and RNase L, these and prior studies (with Bryan Williams, Matty Knight, Jane Cayley, Danny Wreschner and other members of the Kerr lab) firmly established the 2-5A/RNase L system as a participant in the antiviral actions of IFNs [21,28,45,46].…”

Section: Monitoring the Presence And Activation Of Rnase L In Intact mentioning

confidence: 77%

A scientific journey through the 2-5A/RNase L system

Silverman

2007

Cytokine & Growth Factor Reviews

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The antiviral and antitumor actions of interferons are caused, in part, by a remarkable regulated RNA cleavage pathway known as the 2-5A/RNase L system. 2′-5′ linked oligoadenylates (2-5A) are produced from ATP by interferon-inducible synthetases. 2-5A activates pre-existing RNase L, resulting in the cleavage of RNAs within single-stranded regions. Activation of RNase L by 2-5A leads to an antiviral response, although precisely how this happens is a subject of ongoing investigations. Recently, RNase L was identified as the hereditary prostate cancer 1 gene. That finding has led to the discovery of a novel human retrovirus, XMRV. My scientific journey through the 2-5A system recounts some of the highlights of these efforts. Knowledge gained from studies on the 2-5A system could have an impact on development of therapies for important viral pathogens and cancer.Keywords 2-5A; RNase L; interferon; cancer; virus Background on the 2-5A/RNase L systemOver the past thirty-years, investigations into the mechanisms of interferon (IFN) action have elucidated how antiviral innate immunity operates within and between mammalian cells. The focus of my work over this period has been, and continues to be, probing the biology and biochemistry of the 2-5A/RNase L system, and studying its roles in health and disease. My scientific journey, from basic research to clinical studies, are summarized in this monograph. The 2-5A/RNase L system is one the principal pathways by which IFNs suppress viral infections. Exposure of cells to IFNs induces expression of genes that result in an "antiviral state". Type I IFNs bind to the IFN-α receptor 1 (IFNAR1) and IFNAR2 polypeptide chains on cell surfaces initiating JAK-STAT signaling to the IFN stimulated genes (ISGs) [1]. Included among over a hundred different ISGs are genes encoding 2-5A synthetases (OAS) [2,3]. The OAS genes are a family of ISGs that function in the 2-5A/RNase L system (Fig. 1). In humans there are three functional OAS genes (OAS1-3), resulting in 8 to 10 OAS isoforms due to alternative mRNA splicing [4]. In mice, in addition to OAS2 and OAS3 there are 7 separate OAS1 genes, including OAS1b, the flavivirus resistance gene (Flv r ] [5][6][7][8]. When stimulated by dsRNA, the functional OAS proteins produce a series of short 5′-phosphorylated, 2′,5′-linked oligoadenylates collectively referred to as 2-5A [p x 5′A(2′p5′A) n ; x = 1-3; n≥2] from ATP [9]. The first molecular clone for an OAS was obtained by Michel Revel's lab [10]. Biochemical characterization of OAS proteins by Ara Hovanessian's lab [11][12][13][14] and Ganes Sen's lab [15][16][17][18][19] and a crystal structure by Rune Hartmann and Vivien Yee (in collaboration with Ganes Sen and Just Justesen) [20] have led to functional and structural insight into the OAS family of Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, type...

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Section: Monitoring the Presence And Activation Of Rnase L In Intact mentioning

confidence: 77%

A scientific journey through the 2-5A/RNase L system

Silverman

2007

Cytokine & Growth Factor Reviews

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“…9 and Table 2). In studies of ribosomal degradation in cell extracts supplemented with ppp(A2Јp) 3 A, a ligand activating RNase L, cleavage of 28S rRNA gave rise to at least some bands with sizes reminiscent of 5ЈD8 and 3ЈD8 fragments (47,52). Thus, the D8 region seems to be exposed to attacks by intracellular RNase activity.…”

Section: Discussionmentioning

confidence: 99%

Fine Mapping of 28S rRNA Sites Specifically Cleaved in Cells Undergoing Apoptosis

Houge

Robaye

Eikhom

et al. 1995

Molecular and Cellular Biology

115

135

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Bona fide apoptosis in rat and human leukemia cells, rat thymocytes, and bovine endothelial cells was accompanied by limited and specific cleavage of polysome-associated and monosome-associated 28S rRNA, with 18S rRNA being spared. Specific 28S rRNA cleavage was observed in all instances of apoptotic death accompanied by internucleosomal DNA fragmentation, with cleavage of 28S rRNA and of DNA being linked temporally. This indicates that 28S rRNA fragmentation may be as general a feature of apoptosis as internucleosomal DNA fragmentation and that concerted specific cleavage of intra-and extranuclear polynucleotides occurs in apoptosis. Apoptosis-associated cleavage sites were mapped to the 28S rRNA divergent domains D2, D6 (endothelial cells), and D8. The D2 cuts occurred in hairpin loop junctions considered to be buried in the intact ribosome, suggesting that this rRNA region becomes a target for RNase attack in apoptotic cells. D8 was cleaved in two exposed UU(U) sequences in bulge loops. Treatment with agents causing necrotic cell death or aging of cell lysates failed to produce any detectable limited D2 cleavage but did produce a more generalized cleavage in the D8 region. Of potential functional interest was the finding that the primary cuts in D2 exactly flanked a 0.3-kb hypervariable subdomain (D2c), allowing excision of the latter. The implication of hypervariable rRNA domains in apoptosis represents the first association of any functional process with these enigmatic parts of the ribosomes.

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“…As mentioned above, RNase L is an endoribonuclease with minimal sequence specificity. Its first RNA targets to be identified were viral mRNA and rRNA [42][43][44][45]. But more recently, several cellular mRNAs regulated by RNase L were identified.…”

Section: Nih Public Accessmentioning

confidence: 99%

“…How might RNase L activation lead to apoptosis? The degradation of 28S and 18S rRNA by RNase L in intact ribosomes has been long known as a hallmark of IFN and viral infections [42,43]. Cleavage of 28S rRNA by RNase L maps to the L1 protuberance implicated in formation of the exit or E site of the ribosome, possibly interfering with release of deacylated tRNA [112].…”

Section: ) Apoptosismentioning

confidence: 99%

Diverse functions of RNase L and implications in pathology

Bisbal

Silverman

2007

Biochimie

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The endoribonuclease L (RNase L) is the effector of the 2-5A system, a major enzymatic pathway involved in the molecular mechanism of interferons (IFN). RNase L is a very unusual nuclease with a complex mechanism of regulation. It is a latent enzyme, expressed in nearly every mammalian cell type. Its activation requires its binding to a small oligonucleotide, 2-5A. 2-5A is a series of unique 5′-triphosphorylated oligoadenylates with 2′-5′ phosphodiester bonds. By regulating viral and cellular RNA expression, RNase L plays an important role in the antiviral and antiproliferative activities of IFN and contributes to innate immunity and cell metabolism. The 2-5A/RNase L pathway is implicated in mediating apoptosis in response to viral infections and to several types of external stimuli. Several recent studies have suggested that RNase L could have a role in cancer biology and evidence of a tumor suppressor function of RNase L has emerged from studies on the genetics of hereditary prostate cancer. KeywordsInterferon; RNase L; RNA expression; apoptosis; prostate; virus; cancer I) IntroductionThe endoribonuclease L (RNase L) is the effector of the 2-5A system, a major enzymatic pathway regulated by interferons (IFN) [1] (Figure 1). The 2-5A system is one of the two antiviral pathways induced by IFN and activated by double stranded RNA (dsRNA), the other is mediated by the dsRNA dependent protein kinase (PKR) [2]. RNase L is a very unusual nuclease. It is a latent enzyme, expressed in nearly every mammalian cell type. Its activation requires its binding to a small oligonucleotide, 2-5A ( Figure 1). 2-5A itself is very unusual, consisting of a series of 5′-triphosphorylated oligoadenylates with 2′-5′ phosphodiester bonds in contrast to the 3′-5′ linkages found in RNA and DNA. The initial and essential observation was made by Ian Kerr's group in 1974 reporting an IFN-induced increase in the sensitivity of protein synthesis to inhibition by dsRNA [3]. Peter Lengyel's group observed increased nuclease activity in extracts of interferon treated cells incubated with dsRNA [4,5]. The identification by Ian Kerr's group of the activators of this nuclease, 2-5A [6] and of the enzyme responsible for their synthesis, the 2-5A-synthetase [7][8][9], led to the discovery of the 2-5A pathway. Clemens and Williams directly demonstrated a nuclease, now recognized as RNase Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. (Figure 2). The N-terminal domain could be considered as the regulatory domain of RNase L. It is composed of eight complete and one partial ankyrin motifs (R1-R9). Two wal...

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Ribosomal RNA cleavage, nuclease activation and 2-5A (ppp(A2′p)_nA) in interferon-treated cells

Cited by 248 publications

References 23 publications

A scientific journey through the 2-5A/RNase L system

A scientific journey through the 2-5A/RNase L system

Fine Mapping of 28S rRNA Sites Specifically Cleaved in Cells Undergoing Apoptosis

Diverse functions of RNase L and implications in pathology

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Ribosomal RNA cleavage, nuclease activation and 2-5A (ppp(A2′p)nA) in interferon-treated cells

Cited by 248 publications

References 23 publications

A scientific journey through the 2-5A/RNase L system

A scientific journey through the 2-5A/RNase L system

Fine Mapping of 28S rRNA Sites Specifically Cleaved in Cells Undergoing Apoptosis

Diverse functions of RNase L and implications in pathology

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Ribosomal RNA cleavage, nuclease activation and 2-5A (ppp(A2′p)_nA) in interferon-treated cells