المؤلفون: Brenda M. Calderon, Graeme L. Conn

المصدر: The Journal of biological chemistry. 293(41)

مصطلحات موضوعية: 0301 basic medicine, RNA, Untranslated, RNase P, Antiviral protein, RNA-binding protein, Biochemistry, 03 medical and health sciences, Endoribonucleases, 2',5'-Oligoadenylate Synthetase, Humans, Molecular Biology, RNA, Double-Stranded, biology, Dose-Response Relationship, Drug, Chemistry, 2'-5'-Oligoadenylate, Temperature, RNA, Cell Biology, Non-coding RNA, Immunity, Innate, Cell biology, RNA silencing, 030104 developmental biology, A549 Cells, biology.protein, Editors' Picks Highlights, Nucleic Acid Conformation, Regression Analysis, Ribonuclease L

الوصف: The 2′–5′-oligoadenylate synthetase (OAS) family of enzymes sense cytosolic dsRNA, a potent signal of viral infection. In response to dsRNA binding, OAS proteins synthesize the second messenger 2′–5′-linked oligoadenylate that activates the latent ribonuclease L (RNase L). RNase L–mediated degradation of viral and cellular RNAs effectively halts viral replication and further stimulates innate immune responses by inducing type I interferon. The OAS/RNase L pathway is therefore central in innate immune recognition and promotion of antiviral host responses. However, the potential for specific RNA sequences or structures to drive OAS1 activation and the molecular mechanisms by which they act are not currently fully understood. Moreover, the cellular regulators of OAS activity are not well defined. Here, we demonstrate that the human cellular noncoding RNA 886 (nc886) activates OAS1 both in vitro and in human A549 cells. We show that a unique structure present only in one of the two structural conformers adopted by nc886 drives potent OAS1 activation. In contrast, the conformer lacking this unique structure activated OAS1 only very weakly. We also found that formation of this OAS1-activating structural motif depends on the nucleotides in the apical-most loop of nc886 and the adjacent helix. These findings identify a cellular RNA capable of activating the OAS/RNase L pathway in human cells and illustrate the importance of structural elements, and their context, in potentiating OAS1 activity.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::2a3bbb157765957d861b88fdbef9359aTest
https://pubmed.ncbi.nlm.nih.gov/30315089Test

المؤلفون: Mohammad Adnan Siddiqui, Krishnamurthy Malathi

المصدر: The Journal of biological chemistry. 287(52)

مصطلحات موضوعية: RNase P, MAP Kinase Signaling System, viruses, Biology, BAG3, Virus Replication, Biochemistry, Respirovirus Infections, Sendai virus, Mice, eIF-2 Kinase, Interferon, Cell Line, Tumor, Endoribonucleases, Sequestosome-1 Protein, medicine, Autophagy, Cardiovirus Infections, Animals, Humans, Mitogen-Activated Protein Kinase 9, Mitogen-Activated Protein Kinase 8, Encephalomyocarditis virus, Protein kinase A, Molecular Biology, Heat-Shock Proteins, Adaptor Proteins, Signal Transducing, RNA, Double-Stranded, Mice, Knockout, EIF-2 kinase, Cell Biology, Fibroblasts, Embryo, Mammalian, Molecular biology, Protein kinase R, Cell biology, Proto-Oncogene Proteins c-bcl-2, biology.protein, Microtubule-Associated Proteins, Ribonuclease L, medicine.drug, Signal Transduction

الوصف: Autophagy is a tightly regulated mechanism that mediates sequestration, degradation, and recycling of cellular proteins, organelles, and pathogens. Several proteins associated with autophagy regulate host responses to viral infections. Ribonuclease L (RNase L) is activated during viral infections and cleaves cellular and viral single-stranded RNAs, including rRNAs in ribosomes. Here we demonstrate that direct activation of RNase L coordinates the activation of c-Jun N-terminal kinase (JNK) and double-stranded RNA-dependent protein kinase (PKR) to induce autophagy with hallmarks as accumulation of autophagic vacuoles, p62(SQSTM1) degradation and conversion of Microtubule-associated Protein Light Chain 3-I (LC3-I) to LC3-II. Accordingly, treatment of cells with pharmacological inhibitors of JNK or PKR and mouse embryonic fibroblasts (MEFs) lacking JNK1/2 or PKR showed reduced autophagy levels. Furthermore, RNase L-induced JNK activity promoted Bcl-2 phosphorylation, disrupted the Beclin1-Bcl-2 complex and stimulated autophagy. Viral infection with Encephalomyocarditis virus (EMCV) or Sendai virus led to higher levels of autophagy in wild-type (WT) MEFs compared with RNase L knock out (KO) MEFs. Inhibition of RNase L-induced autophagy using Bafilomycin A1 or 3-methyladenine suppressed viral growth in initial stages; in later stages autophagy promoted viral replication dampening the antiviral effect. Induction of autophagy by activated RNase L is independent of the paracrine effects of interferon (IFN). Our findings suggest a novel role of RNase L in inducing autophagy affecting the outcomes of viral pathogenesis.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::261670776076202a1dd354a5b3760e5fTest
https://pubmed.ncbi.nlm.nih.gov/23109342Test

المؤلفون: Beihua Dong, Robert H. Silverman

المصدر: The Journal of biological chemistry. 270(8)

مصطلحات موضوعية: Insecta, RNase P, Endoribonuclease activity, Protein subunit, Size-exclusion chromatography, Biochemistry, RNase PH, law.invention, Biopolymers, law, Endoribonucleases, Animals, Humans, Cloning, Molecular, Phosphorylation, Molecular Biology, Cells, Cultured, Oligoribonucleotides, biology, Adenine Nucleotides, Cell Biology, Enzyme Activation, RNase MRP, Cross-Linking Reagents, biology.protein, Recombinant DNA, Chromatography, Gel, Electrophoresis, Polyacrylamide Gel, Female, Baculoviridae, Ribonuclease L, Protein Binding

الوصف: 2-5A-dependent RNase is an interferon-inducible enzyme that requires 5′-phosphorylated, 2′,5′-linked oligoadenylates (2-5A) for its endoribonuclease activity against single-stranded RNAs. We demonstrate here that recombinant, human 2-5A-dependent RNase forms stable homodimers during its stimulation by 2-5A. The protein dimers were observed to form only upon binding to 2-5A, as shown using gel filtration chromatography and chemical cross-linking and after centrifugation in glycerol gradients. A monoclonal antibody to 2-5A-dependent RNase was prepared and used to probe the subunit structure of the enzyme in the presence or absence of 2-5A. Using oligoadenylates of different length, structure, and 5′-phosphorylation states we determined that conversion of 2-5A-dependent RNase from its monomeric, inactive form to its homodimeric, active form required the presence of functional 2-5A. These results demonstrate that the catalytically active form of 2-5A-dependent RNase is a homodimer.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::c047984746c70db20bfc6404746bfa47Test
https://pubmed.ncbi.nlm.nih.gov/7876164Test