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1.
Nature ; 607(7920): 769-775, 2022 07.
Artigo em Inglês | MEDLINE | ID: mdl-35859177

RESUMO

The RNA-editing enzyme ADAR1 is essential for the suppression of innate immune activation and pathology caused by aberrant recognition of self-RNA, a role it carries out by disrupting the duplex structure of endogenous double-stranded RNA species1,2. A point mutation in the sequence encoding the Z-DNA-binding domain (ZBD) of ADAR1 is associated with severe autoinflammatory disease3-5. ZBP1 is the only other ZBD-containing mammalian protein6, and its activation can trigger both cell death and transcriptional responses through the kinases RIPK1 and RIPK3, and the protease caspase 8 (refs. 7-9). Here we show that the pathology caused by alteration of the ZBD of ADAR1 is driven by activation of ZBP1. We found that ablation of ZBP1 fully rescued the overt pathology caused by ADAR1 alteration, without fully reversing the underlying inflammatory program caused by this alteration. Whereas loss of RIPK3 partially phenocopied the protective effects of ZBP1 ablation, combined deletion of caspase 8 and RIPK3, or of caspase 8 and MLKL, unexpectedly exacerbated the pathogenic effects of ADAR1 alteration. These findings indicate that ADAR1 is a negative regulator of sterile ZBP1 activation, and that ZBP1-dependent signalling underlies the autoinflammatory pathology caused by alteration of ADAR1.


Assuntos
Adenosina Desaminase , Doenças do Sistema Imunitário , Inflamação , Mutação , Proteínas de Ligação a RNA , Adenosina Desaminase/genética , Adenosina Desaminase/metabolismo , Animais , Caspase 8/genética , Caspase 8/metabolismo , Morte Celular , Deleção de Genes , Doenças do Sistema Imunitário/genética , Doenças do Sistema Imunitário/metabolismo , Doenças do Sistema Imunitário/patologia , Inflamação/genética , Inflamação/metabolismo , Inflamação/patologia , Mamíferos/genética , Proteínas Quinases/deficiência , Proteínas Quinases/genética , RNA de Cadeia Dupla/metabolismo , Proteínas de Ligação a RNA/genética , Proteínas de Ligação a RNA/metabolismo , Proteína Serina-Treonina Quinases de Interação com Receptores/deficiência , Proteína Serina-Treonina Quinases de Interação com Receptores/genética , Transdução de Sinais
2.
Nature ; 607(7920): 776-783, 2022 07.
Artigo em Inglês | MEDLINE | ID: mdl-35859176

RESUMO

Mutations of the ADAR1 gene encoding an RNA deaminase cause severe diseases associated with chronic activation of type I interferon (IFN) responses, including Aicardi-Goutières syndrome and bilateral striatal necrosis1-3. The IFN-inducible p150 isoform of ADAR1 contains a Zα domain that recognizes RNA with an alternative left-handed double-helix structure, termed Z-RNA4,5. Hemizygous ADAR1 mutations in the Zα domain cause type I IFN-mediated pathologies in humans2,3 and mice6-8; however, it remains unclear how the interaction of ADAR1 with Z-RNA prevents IFN activation. Here we show that Z-DNA-binding protein 1 (ZBP1), the only other protein in mammals known to harbour Zα domains9, promotes type I IFN activation and fatal pathology in mice with impaired ADAR1 function. ZBP1 deficiency or mutation of its Zα domains reduced the expression of IFN-stimulated genes and largely prevented early postnatal lethality in mice with hemizygous expression of ADAR1 with mutated Zα domain (Adar1mZα/- mice). Adar1mZα/- mice showed upregulation and impaired editing of endogenous retroelement-derived complementary RNA reads, which represent a likely source of Z-RNAs activating ZBP1. Notably, ZBP1 promoted IFN activation and severe pathology in Adar1mZα/- mice in a manner independent of RIPK1, RIPK3, MLKL-mediated necroptosis and caspase-8-dependent apoptosis, suggesting a novel mechanism of action. Thus, ADAR1 prevents endogenous Z-RNA-dependent activation of pathogenic type I IFN responses by ZBP1, suggesting that ZBP1 could contribute to type I interferonopathies caused by ADAR1 mutations.


Assuntos
Adenosina Desaminase , Interferon Tipo I , Proteínas de Ligação a RNA , Adenosina Desaminase/genética , Adenosina Desaminase/metabolismo , Animais , Apoptose , Caspase 8/metabolismo , Interferon Tipo I/antagonistas & inibidores , Interferon Tipo I/imunologia , Camundongos , Mutação , Necroptose , RNA de Cadeia Dupla/metabolismo , Proteínas de Ligação a RNA/química , Proteínas de Ligação a RNA/genética , Proteínas de Ligação a RNA/metabolismo
3.
Front Immunol ; 13: 941931, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35812450

RESUMO

Toll-like receptors (TLRs) respond to pathogen constituents, such as microbial lipids and nucleic acids (NAs). TLRs recognize NAs in endosomal compartments. Structural and functional studies have shown that recognition of NAs by TLRs depends on NA processing by RNases and DNases. DNase II-dependent DNA degradation is required for TLR9 responses to single-stranded DNAs, whereas RNase T2-dependent RNA degradation enables TLR7 and TLR8 to respond to nucleosides and oligoribonucleotides. In contrast, RNases and DNases negatively regulate TLR responses by degrading their ligands. RNase T2 negatively regulates TLR3 responses to degrading the TLR3 ligand double-stranded RNAs. Therefore, NA metabolism in the endosomal compartments affects the endosomal TLR responses. Dysregulation of NA metabolism in the endosomal compartment drives the TLR-dependent pathologies in human diseases.


Assuntos
Ácidos Nucleicos , Endossomos/metabolismo , Humanos , Ligantes , Ácidos Nucleicos/metabolismo , RNA de Cadeia Dupla/metabolismo , Receptor 3 Toll-Like/metabolismo , Receptores Toll-Like/metabolismo
4.
PLoS Pathog ; 18(7): e1010688, 2022 07.
Artigo em Inglês | MEDLINE | ID: mdl-35793357

RESUMO

Herpes simplex virus type 1 (HSV-1) is a common virus of mankind and HSV-1 infections are a significant cause of blindness. The current antiviral treatment of herpes infection relies on acyclovir and related compounds. However, acyclovir resistance emerges especially in the long term prophylactic treatment that is required for prevention of recurrent herpes keratitis. Earlier we have established antiviral siRNA swarms, targeting sequences of essential genes of HSV, as effective means of silencing the replication of HSV in vitro or in vivo. In this study, we show the antiviral efficacy of 2´-fluoro modified antiviral siRNA swarms against HSV-1 in human corneal epithelial cells (HCE). We studied HCE for innate immunity responses to HSV-1, to immunostimulatory cytotoxic double stranded RNA, and to the antiviral siRNA swarms, with or without a viral challenge. The panel of studied innate responses included interferon beta, lambda 1, interferon stimulated gene 54, human myxovirus resistance protein A, human myxovirus resistance protein B, toll-like receptor 3 and interferon kappa. Our results demonstrated that HCE cells are a suitable model to study antiviral RNAi efficacy and safety in vitro. In HCE cells, the antiviral siRNA swarms targeting the HSV UL29 gene and harboring 2´-fluoro modifications, were well tolerated, induced only modest innate immunity responses, and were highly antiviral with more than 99% inhibition of viral release. The antiviral effect of the 2'-fluoro modified swarm was more apparent than that of the unmodified antiviral siRNA swarm. Our results encourage further research in vitro and in vivo on antiviral siRNA swarm therapy of corneal HSV infection, especially with modified siRNA swarms.


Assuntos
Herpes Simples , Herpesvirus Humano 1 , Aciclovir/metabolismo , Aciclovir/farmacologia , Antivirais/metabolismo , Antivirais/farmacologia , Células Epiteliais/metabolismo , Herpes Simples/genética , Herpes Simples/terapia , Herpesvirus Humano 1/fisiologia , Humanos , RNA de Cadeia Dupla/metabolismo , RNA Interferente Pequeno/genética , RNA Interferente Pequeno/metabolismo , Replicação Viral/genética
5.
PLoS Biol ; 20(6): e3001668, 2022 06.
Artigo em Inglês | MEDLINE | ID: mdl-35679279

RESUMO

The mosquito's innate immune system defends against a variety of pathogens, and the conserved siRNA pathway plays a central role in the control of viral infections. Here, we show that transgenic overexpression of Dicer2 (Dcr2) or R2d2 resulted in an accumulation of 21-nucleotide viral sequences that was accompanied by a significant suppression of dengue virus (DENV), Zika virus (ZIKV), and chikungunya virus (CHIKV) replication, thus indicating the broad-spectrum antiviral response mediated by the siRNA pathway that can be applied for the development of novel arbovirus control strategies. Interestingly, overexpression of Dcr2 or R2d2 regulated the mRNA abundance of a variety of antimicrobial immune genes, pointing to additional functions of DCR2 and R2D2 as well as cross-talk between the siRNA pathway and other immune pathways. Accordingly, transgenic overexpression of Dcr2 or R2d2 resulted in a lesser proliferation of the midgut microbiota and increased resistance to bacterial and fungal infections.


Assuntos
Aedes , Vírus da Dengue , Dengue , Infecção por Zika virus , Zika virus , Animais , Animais Geneticamente Modificados , Antibacterianos/metabolismo , Antifúngicos , Vírus da Dengue/genética , Humanos , RNA de Cadeia Dupla/metabolismo , RNA Interferente Pequeno/genética , RNA Interferente Pequeno/metabolismo , Zika virus/genética
6.
Int J Mol Sci ; 23(11)2022 May 31.
Artigo em Inglês | MEDLINE | ID: mdl-35682860

RESUMO

RNA interference (RNAi) technology is a promising approach used in pest control. The efficiency of RNAi varies considerably among different insect species, and growing evidence suggests that degradation of double-stranded RNA (dsRNA) prior to uptake is an important factor that limits RNAi efficiency in insects. Our recent work on fall webworm (Hyphantria cunea), an important invasive pest in China, showed a relatively low silencing efficiency of RNAi through dsRNA injection, which is considered the most feasible dsRNA delivery method for inducing RNAi, and the factors involved in the mechanism remain unknown. Herein, we first detected the dsRNA-degrading activity in the hemolymph and gut content of H. cunea in ex vivo assays and observed rapid degradation of dsRNA, especially in the hemolymph, which was complete within only 10 min. To determine whether dsRNA degradation could contribute to the low effectiveness of RNAi in H. cunea, four dsRNA nuclease (dsRNase) genes, HcdsRNase1, HcdsRNase2, HcdsRNase3, and HcdsRNase4, were identified by homology searching against the H. cunea transcriptome database, and their transcript levels were subsequently investigated in different tissues, developmental stages, and after dsRNA injection. Our results show that HcdsRNases are highly expressed mainly in gut tissues and hemolymph, and the expression of HcdsRNase3 and HcdsRNase4 were significantly upregulated by dsGFP induction. RNAi-of-RNAi studies, using HcCht5 as a reporter gene, demonstrated that silencing HcdsRNase3 and HcdsRNase4 significantly increases RNAi efficacy via dsHcCht5 injection, and co-silencing these two HcdsRNase genes results in a more significant improvement in efficacy. These results confirm that the RNAi efficacy in H. cunea through dsRNA injection is certainly impaired by dsRNase activity, and that blocking HcdsRNases could potentially improve RNAi, providing a reference for related studies on insects where RNAi has low efficiency.


Assuntos
Mariposas , RNA de Cadeia Dupla , Animais , Endonucleases/metabolismo , Hemolinfa/metabolismo , Insetos/metabolismo , Mariposas/genética , Mariposas/metabolismo , Interferência de RNA , RNA de Cadeia Dupla/genética , RNA de Cadeia Dupla/metabolismo
7.
Pestic Biochem Physiol ; 184: 105106, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-35715045

RESUMO

The brown planthopper (BPH), Nilaparvata lugens (Stål), is one of the most destructive pests in rice-growing regions of Asia. Extensive studies have suggested that SWI/SNF chromatin remodeling ATPase Brahma (BRM) plays multiple roles in the insect model Drosophila. Yet much less is known about the physiological properties for NlBRM. In the present study, the cloned full-length cDNA of NlBRM was 5637 bp and contained an ORF of 5292 bp encoding a 194.53 kD protein. The spatiotemporal dynamics of NlBRM was investigated by qPCR, which showed that it was abundantly expressed in the egg and ovary. Then significant downregulation of NlBRM by dsRNA injection had a relatively greater impact on female survival than male. Moreover, the number of oviposition marks of the NlBRM-RNAi females were declined by 61.11% - 73.33% compared with the controls during the subsequent 5 days after dsRNA injection. Meanwhile, the number of newly hatched BPH nymphs also decreased correspondingly by 93.56% - 100%. Phenotypic analysis revealed that none of normally banana-shaped eggs were discernable in the ovaries of NlBRM-deficient females, where mRNA expression of N. lugens vitellogenin gene was also reduced. Our results demonstrated that NlBRM played a crucial role in ovarian development and fecundity of BPH, likely by regulating the vitellogenin gene in vivo, which could be as a promising target for parental RNAi-based control of this serious rice pest.


Assuntos
Adenosina Trifosfatases , Hemípteros , Oryza , Adenosina Trifosfatases/metabolismo , Animais , Cromatina/metabolismo , Montagem e Desmontagem da Cromatina , Feminino , Hemípteros/metabolismo , Humanos , Proteínas de Insetos/genética , Proteínas de Insetos/metabolismo , Masculino , Oryza/metabolismo , Interferência de RNA , RNA de Cadeia Dupla/genética , RNA de Cadeia Dupla/metabolismo , Vitelogeninas/genética
8.
Nature ; 607(7918): 393-398, 2022 07.
Artigo em Inglês | MEDLINE | ID: mdl-35768503

RESUMO

In flies, Argonaute2 (Ago2) and small interfering RNA (siRNA) form an RNA-induced silencing complex to repress viral transcripts1. The RNase III enzyme Dicer-2 associates with its partner protein R2D2 and cleaves long double-stranded RNAs to produce 21-nucleotide siRNA duplexes, which are then loaded into Ago2 in a defined orientation2-5. Here we report cryo-electron microscopy structures of the Dicer-2-R2D2 and Dicer-2-R2D2-siRNA complexes. R2D2 interacts with the helicase domain and the central linker of Dicer-2 to inhibit the promiscuous processing of microRNA precursors by Dicer-2. Notably, our structure represents the strand-selection state in the siRNA-loading process, and reveals that R2D2 asymmetrically recognizes the end of the siRNA duplex with the higher base-pairing stability, and the other end is exposed to the solvent and is accessible by Ago2. Our findings explain how R2D2 senses the thermodynamic asymmetry of the siRNA and facilitates the siRNA loading into Ago2 in a defined orientation, thereby determining which strand of the siRNA duplex is used by Ago2 as the guide strand for target silencing.


Assuntos
Microscopia Crioeletrônica , Proteínas de Drosophila , RNA Helicases , RNA de Cadeia Dupla , RNA Interferente Pequeno , Proteínas de Ligação a RNA , Ribonuclease III , Animais , Proteínas Argonauta/metabolismo , Pareamento de Bases , Proteínas de Drosophila/química , Proteínas de Drosophila/metabolismo , Proteínas de Drosophila/ultraestrutura , Drosophila melanogaster/química , Drosophila melanogaster/genética , Drosophila melanogaster/metabolismo , MicroRNAs/metabolismo , Multimerização Proteica , RNA Helicases/química , RNA Helicases/metabolismo , RNA Helicases/ultraestrutura , Interferência de RNA , RNA de Cadeia Dupla/química , RNA de Cadeia Dupla/metabolismo , RNA de Cadeia Dupla/ultraestrutura , RNA Interferente Pequeno/química , RNA Interferente Pequeno/metabolismo , RNA Interferente Pequeno/ultraestrutura , Proteínas de Ligação a RNA/química , Proteínas de Ligação a RNA/metabolismo , Proteínas de Ligação a RNA/ultraestrutura , Complexo de Inativação Induzido por RNA/metabolismo , Ribonuclease III/química , Ribonuclease III/metabolismo , Ribonuclease III/ultraestrutura
9.
Nature ; 607(7918): 399-406, 2022 07.
Artigo em Inglês | MEDLINE | ID: mdl-35768513

RESUMO

Small interfering RNAs (siRNAs) are the key components for RNA interference (RNAi), a conserved RNA-silencing mechanism in many eukaryotes1,2. In Drosophila, an RNase III enzyme Dicer-2 (Dcr-2), aided by its cofactor Loquacious-PD (Loqs-PD), has an important role in generating 21 bp siRNA duplexes from long double-stranded RNAs (dsRNAs)3,4. ATP hydrolysis by the helicase domain of Dcr-2 is critical to the successful processing of a long dsRNA into consecutive siRNA duplexes5,6. Here we report the cryo-electron microscopy structures of Dcr-2-Loqs-PD in the apo state and in multiple states in which it is processing a 50 bp dsRNA substrate. The structures elucidated interactions between Dcr-2 and Loqs-PD, and substantial conformational changes of Dcr-2 during a dsRNA-processing cycle. The N-terminal helicase and domain of unknown function 283 (DUF283) domains undergo conformational changes after initial dsRNA binding, forming an ATP-binding pocket and a 5'-phosphate-binding pocket. The overall conformation of Dcr-2-Loqs-PD is relatively rigid during translocating along the dsRNA in the presence of ATP, whereas the interactions between the DUF283 and RIIIDb domains prevent non-specific cleavage during translocation by blocking the access of dsRNA to the RNase active centre. Additional ATP-dependent conformational changes are required to form an active dicing state and precisely cleave the dsRNA into a 21 bp siRNA duplex as confirmed by the structure in the post-dicing state. Collectively, this study revealed the molecular mechanism for the full cycle of ATP-dependent dsRNA processing by Dcr-2-Loqs-PD.


Assuntos
Microscopia Crioeletrônica , Proteínas de Drosophila , Drosophila melanogaster , RNA Helicases , RNA de Cadeia Dupla , RNA Interferente Pequeno , Proteínas de Ligação a RNA , Ribonuclease III , Trifosfato de Adenosina , Animais , Sítios de Ligação , Proteínas de Drosophila/química , Proteínas de Drosophila/metabolismo , Proteínas de Drosophila/ultraestrutura , Fosfatos/metabolismo , Conformação Proteica , RNA Helicases/química , RNA Helicases/metabolismo , RNA Helicases/ultraestrutura , RNA de Cadeia Dupla/química , RNA de Cadeia Dupla/metabolismo , RNA de Cadeia Dupla/ultraestrutura , RNA Interferente Pequeno/química , RNA Interferente Pequeno/metabolismo , RNA Interferente Pequeno/ultraestrutura , Proteínas de Ligação a RNA/química , Proteínas de Ligação a RNA/metabolismo , Proteínas de Ligação a RNA/ultraestrutura , Ribonuclease III/química , Ribonuclease III/metabolismo , Ribonuclease III/ultraestrutura
10.
J Virol ; 96(14): e0192621, 2022 07 27.
Artigo em Inglês | MEDLINE | ID: mdl-35758691

RESUMO

Virion host shutoff (vhs) protein is an endoribonuclease encoded by herpes simplex virus 1 (HSV1). vhs causes several changes to the infected cell environment that favor the translation of late (L) virus proteins: cellular mRNAs are degraded, immediate early (IE) and early (E) viral transcripts are sequestered in the nucleus with polyA binding protein (PABPC1), and dsRNA is degraded to help dampen the PKR-dependent stress response. To further our understanding of the cell biology of vhs, we constructed a virus expressing vhs tagged at its C terminus with GFP. When first expressed, vhs-GFP localized to juxtanuclear clusters, and later it colocalized and interacted with its binding partner VP16, and was packaged into virions. Despite vhs-GFP maintaining activity when expressed in isolation, it failed to degrade mRNA or relocalise PABPC1 during infection, while viral transcript levels were similar to those seen for a vhs knockout virus. PKR phosphorylation was also enhanced in vhs-GFP infected cells, which is in line with a failure to degrade dsRNA. Nonetheless, mRNA FISH revealed that as in Wt but not Dvhs infection, IE and E, but not L transcripts were retained in the nucleus of vhs-GFP infected cells at late times. These results revealed that the vhs-induced nuclear retention of IE and E transcripts was dependent on vhs expression but not on its endoribonuclease activity, uncoupling these two functions of vhs. IMPORTANCE Like many viruses, herpes simplex virus 1 (HSV1) expresses an endoribonuclease, the virion host shutoff (vhs) protein, which regulates the RNA environment of the infected cell and facilitates the classical cascade of virus protein translation. It does this by causing the degradation of some mRNA molecules and the nuclear retention of others. Here, we describe a virus expressing vhs tagged at its C terminus with a green fluorescent protein (GFP) and show that the vhs-GFP fusion protein retains the physical properties of native vhs but does not induce the degradation of mRNA. Nonetheless, vhs-GFP maintains the ability to trap the early virus transcriptome in the nucleus to favor late protein translation, proving for the first time that mRNA degradation is not a prerequisite for vhs effects on the nuclear transcriptome. This virus, therefore, has uncoupled the nuclear retention and degradation activities of vhs, providing a new understanding of vhs during infection.


Assuntos
Herpes Simples , Herpesvirus Humano 1 , Endorribonucleases/metabolismo , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Herpes Simples/metabolismo , Herpesvirus Humano 1/fisiologia , Humanos , Estabilidade de RNA , RNA de Cadeia Dupla/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Ribonucleases/genética , Ribonucleases/metabolismo , Transcriptoma , Vírion/metabolismo
11.
Nucleic Acids Res ; 50(9): 4840-4859, 2022 05 20.
Artigo em Inglês | MEDLINE | ID: mdl-35524566

RESUMO

Extrahepatic delivery of small interfering RNAs (siRNAs) may have applications in the development of novel therapeutic approaches. However, reports on such approaches are limited, and the scarcity of reports concerning the systemically targeted delivery of siRNAs with effective gene silencing activity presents a challenge. We herein report for the first time the targeted delivery of CD206-targetable chemically modified mannose-siRNA (CMM-siRNA) conjugates to macrophages and dendritic cells (DCs). CMM-siRNA exhibited a strong binding ability to CD206 and selectively delivered contents to CD206-expressing macrophages and DCs. Furthermore, the conjugates demonstrated strong gene silencing ability with long-lasting effects and protein downregulation in CD206-expressing cells in vivo. These findings could broaden the use of siRNA technology, provide additional therapeutic opportunities, and establish a basis for further innovative approaches for the targeted delivery of siRNAs to not only macrophages and DCs but also other cell types.


Assuntos
RNA Interferente Pequeno , Células Dendríticas , Sistemas de Liberação de Medicamentos , Ligantes , Macrófagos/metabolismo , Manose/metabolismo , RNA de Cadeia Dupla/metabolismo , RNA Interferente Pequeno/metabolismo , RNA Interferente Pequeno/uso terapêutico
12.
Int J Mol Sci ; 23(9)2022 Apr 29.
Artigo em Inglês | MEDLINE | ID: mdl-35563369

RESUMO

Many plant viruses express suppressor proteins (VSRs) that can inhibit RNA silencing, a central component of antiviral plant immunity. The most common activity of VSRs is the high-affinity binding of virus-derived siRNAs and thus their sequestration from the silencing process. Since siRNAs share large homologies with miRNAs, VSRs like the Tombusvirus p19 may also bind miRNAs and in this way modulate cellular gene expression at the post-transcriptional level. Interestingly, the binding affinity of p19 varies considerably between different miRNAs, and the molecular determinants affecting this property have not yet been adequately characterized. Addressing this, we analyzed the binding of p19 to the miRNAs 162 and 168, which regulate the expression of the important RNA silencing constituents Dicer-like 1 (DCL1) and Argonaute 1 (AGO1), respectively. p19 binds miRNA162 with similar high affinity as siRNA, whereas the affinity for miRNA168 is significantly lower. We show that specific molecular features, such as mismatches and 'G-U wobbles' on the RNA side and defined amino acid residues on the VSR side, mediate this property. Our observations highlight the remarkable adaptation of VSR binding affinities to achieve differential effects on host miRNA activities. Moreover, they show that even minimal changes, i.e., a single base pair in a miRNA duplex, can have significant effects on the efficiency of the plant antiviral immune response.


Assuntos
MicroRNAs , Tombusvirus , Antivirais/metabolismo , MicroRNAs/genética , MicroRNAs/metabolismo , Imunidade Vegetal/genética , Interferência de RNA , RNA de Cadeia Dupla/metabolismo , RNA Interferente Pequeno/genética , RNA Interferente Pequeno/metabolismo , Tombusvirus/genética
13.
J Agric Food Chem ; 70(22): 6634-6643, 2022 Jun 08.
Artigo em Inglês | MEDLINE | ID: mdl-35612305

RESUMO

Developing safe and effective double-stranded RNA (dsRNA) delivery systems remains a major challenge for gene silencing, especially in lepidopteran insects. This study evaluated the protamine sulfate (PS)/lipid/dsRNA nanoparticle (NP) delivery system for RNA interference (RNAi) in cells and larvae of the fall armyworm (FAW), Spodoptera frugiperda, a major worldwide pest. A highly efficient gene delivery formulation was prepared using a cationic biopolymer, PS, and a cationic lipid, Cellfectin (CF), complexed with dsRNA. The NPs were prepared by a two-step self-assembly method. The formation of NPs was revealed by dynamic light scattering and transmission electron microscopy. The formation of CF/dsRNA/PS NPs was spherical in shape and size, ranging from 20 to 100 nm with a positive charge (+23.3 mV). Interestingly, prepared CF/dsRNA/PS NPs could protect dsRNA (95%) from nuclease degradation and thus significantly improve the stability of dsRNA. Formulations prepared by combining EGFP DNA with CF/PS increased transfection efficiency in Sf9 cells compared to PS/EGFP and CF/EGFP NPs. Also, the PS/CF/dsRNA NPs enhanced the endosomal escape for the intracellular delivery of dsRNA. The gene knockdown efficiency was assessed in Sf9 Luciferase (Luc) stable cells after a 72 h incubation with CF/dsRNA/PS, PS/dsRNA, CF/dsRNA, or naked dsRNA. Knockdown of the Luc gene was detected in CF/dsRNA/PS (76%) and PS/dsRNA (42.4%) not CF/dsRNA (19.5%) and naked dsRNA (10.3%) in Sf9 Luc cells. Moreover, CF/dsIAP/PS (25 µg of dsRNA targeting the inhibitor of apoptosis, IAP, gene of FAW) NPs showed knockdown of the IAP gene (39.5%) and mortality (55%) in FAW larvae. These results highlight the potential application of PS/lipid/dsRNA NPs for RNA-mediated control of insect pests.


Assuntos
Nanopartículas , RNA de Cadeia Dupla , Animais , Larva , Lipídeos/farmacologia , Protaminas/genética , Protaminas/metabolismo , Protaminas/farmacologia , Interferência de RNA , RNA de Cadeia Dupla/genética , RNA de Cadeia Dupla/metabolismo , Spodoptera
14.
Mol Plant ; 15(7): 1176-1191, 2022 07 04.
Artigo em Inglês | MEDLINE | ID: mdl-35619559

RESUMO

Expression of double-stranded RNAs in plastids offers great potential for the efficient control of chewing insects. However, many insect pests do not consume plant tissue but rather feed on the host plant by sucking sap from the vascular system. Whether or not plastid-mediated RNA interference (RNAi) can be employed to control sap-sucking insects is unknown. Here, we show that five species of sap-sucking hemipteran insects acquire plastid RNA upon feeding on plants. We generated both nuclear transgenic and transplastomic tobacco plants expressing double-stranded RNAs targeting the MpDhc64C gene, a newly identified efficient target gene of RNAi whose silencing causes lethality to the green peach aphid Myzus persicae. In a whole-plant bioassay, transplastomic plants exhibited significant resistance to aphids, as evidenced by reduced insect survival, impaired fecundity, and decreased weight of survivors. The protective effect was comparable with that conferred by the best-performing nuclear transgenic plants. We found that the proportion of aphids on mature leaves of transplastomic plants was significantly lower compared with that of nuclear transgenic plants. When aphids were allowed to infest only the mature leaves, transplastomic plants grew significantly faster and were overall better protected from the pest compared with nuclear transgenic plants. When monitored by electrical-penetration-graph analyses and aphid avoidance response experiments, the insects displayed remarkable alterations in feeding behavior, which was different in nuclear transgenic and transplastomic plants, likely reflecting specific avoidance strategies to toxic RNA molecules. Taken together, our study demonstrates that plastid-mediated RNAi provides an efficient strategy for controlling at least some sap-sucking insect pests, even though there is most likely no or only very little chloroplast RNA in the sap.


Assuntos
Afídeos , Animais , Afídeos/genética , Insetos , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/metabolismo , Interferência de RNA , RNA de Cadeia Dupla/genética , RNA de Cadeia Dupla/metabolismo
15.
Int J Mol Sci ; 23(10)2022 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-35628133

RESUMO

Recent investigations have shown the possibility of artificial induction of RNA interference (RNAi) via plant foliar treatments with naked double-stranded RNA (dsRNA) to silence essential genes in plant fungal pathogens or to target viral RNAs. Furthermore, several studies have documented the downregulation of plant endogenous genes via external application of naked gene-specific dsRNAs and siRNAs to the plant surfaces. However, there are limited studies on the dsRNA processing and gene silencing mechanisms after external dsRNA application. Such studies would assist in the development of innovative tools for crop improvement and plant functional studies. In this study, we used exogenous gene-specific dsRNA to downregulate the gene of chalcone synthase (CHS), the key enzyme in the flavonoid/anthocyanin biosynthesis pathway, in Arabidopsis. The nonspecific NPTII-dsRNA encoding the nonrelated neomycin phosphotransferase II bacterial gene was used to treat plants in order to verify that any observed effects and processing of AtCHS mRNA were sequence specific. Using high-throughput small RNA (sRNA) sequencing, we obtained six sRNA-seq libraries for plants treated with water, AtCHS-dsRNA, or NPTII-dsRNA. After plant foliar treatments, we detected the emergence of a large number of AtCHS- and NPTII-encoding sRNAs, while there were no such sRNAs after control water treatment. Thus, the exogenous AtCHS-dsRNAs were processed into siRNAs and induced RNAi-mediated AtCHS gene silencing. The analysis showed that gene-specific sRNAs mapped to the AtCHS and NPTII genes unevenly with peak read counts at particular positions, involving primarily the sense strand, and documented a gradual decrease in read counts from 17-nt to 30-nt sRNAs. Results of the present study highlight a significant potential of exogenous dsRNAs as a promising strategy to induce RNAi-based downregulation of plant gene targets for plant management and gene functional studies.


Assuntos
Arabidopsis , RNA de Cadeia Dupla , Aciltransferases , Arabidopsis/genética , Arabidopsis/metabolismo , Interferência de RNA , RNA de Cadeia Dupla/genética , RNA de Cadeia Dupla/metabolismo , RNA Interferente Pequeno/genética , RNA Interferente Pequeno/metabolismo
16.
Exp Parasitol ; 238: 108246, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-35460697

RESUMO

Meloidogyne incognita is the most economically important species of the root-knot nematode complex causing damage to several crops worldwide. During parasitism in host plants, M. incognita secretes several effector proteins to suppress the plant immune system, manipulate the plant cell cycle, and promote parasitism. Several effector proteins have been identified, but their relationship with plant parasitism by M. incognita has not been fully confirmed. Herein, the Minc01696, Minc00344, and Minc00801 putative effector genes were evaluated to assess their importance during soybean and Nicotiana tabacum parasitism by M. incognita. For this study, we used in planta RNAi technology to overexpress dsRNA molecules capable of producing siRNAs that target and downregulate these nematode effector genes. Soybean composite roots and N. tabacum lines were successfully generated, and susceptibility level to M. incognita was evaluated. Consistently, both transgenic soybean roots and transgenic N. tabacum lines carrying the RNAi strategy showed reduced susceptibility to M. incognita. The number of galls per plant and the number of egg masses per plant were reduced by up to 85% in transgenic soybean roots, supported by the downregulation of effector genes in M. incognita during parasitism. Similarly, the number of galls per plant, the number of egg masses per plant, and the nematode reproduction factor were reduced by up to 83% in transgenic N. tabacum lines, which was also supported by the downregulation of the Minc00801 effector gene during parasitism. Therefore, our data indicate that all three effector genes can be a target in the development of new biotechnological tools based on the RNAi strategy in economically important crops for M. incognita control.


Assuntos
Doenças das Plantas , Tylenchoidea , Animais , Doenças das Plantas/prevenção & controle , Raízes de Plantas , Interferência de RNA , RNA de Cadeia Dupla/genética , RNA de Cadeia Dupla/metabolismo , Soja/genética , Tabaco/genética , Tylenchoidea/genética
17.
PLoS One ; 17(4): e0266751, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35395036

RESUMO

The Asian corn borer, Ostrinia furnacalis, is a serious insect pest that can infest corn leaves and stems. Due to its internal feeding behavior, its larvae are not exposed to insecticides that are usually sprayed for pest control. To minimize crop damage caused by O. furnacalis, improving insect resistance trait of corn has been considered as an optimal control tactic. This study screened 27 corn varieties for their insect resistance trait and selected three varieties of Ilmichal (IM), P3394, and Kwangpyeongok (KP) that showed insect resistance trait. O. furnacalis larvae did not show any significant difference in preference between these three insect-resistant corn varieties and a control susceptible variety. However, these resistant varieties after ingestion significantly interfered with larval development of O. furnacalis. This suggests that the insect resistance trait is induced by antibiosis, but not by antixenosis. Indeed, larvae fed with these varieties suffered from low chymotrypsin (CHY) activities in the midgut juice. To determine the target CHY inhibited by resistant corn varieties, a total of nine CHY genes (Of-CHY1~Of-CHY9) were predicted from the transcriptome of O. furnacalis. Six genes (Of-CHY1~Of-CHY6) were expressed in all developmental stages and tissues. Especially, Of-CHY3 was highly expressed in the midgut of O. furnacalis larvae. RNA interference (RNAi) using double-stranded RNA (dsRNA) specific to Of-CHY3 (2 µg of dsRNA injected to each L5 larva) resulted in significant reduction of Of-CHY3 expression level at 24 h post-treatment. Feeding L3 larvae with this dsRNA also significantly suppressed the expression level of Of-CHY3 and reduced its enzyme activity at 24 h post-treatment. A recombinant Escherichia coli expressing dsRNA specific to Of-CHY3 was constructed using L4440 vector. Feeding such recombinant bacteria suppressed the expression level of Of-CHY3 and prevented larval development of O. furnacalis. These results suggest that the three resistant varieties can produce a resistance factor(s) to inhibit the CHY activity of O. furnacalis and suppress larval growth. This study suggests that CHY might be an inhibition target in O. furnacalis for breeding insect-resistant corns.


Assuntos
Mariposas , Zea mays , Animais , Quimotripsina/genética , Quimotripsina/metabolismo , Proteínas de Insetos/genética , Proteínas de Insetos/metabolismo , Larva , Mariposas/fisiologia , Melhoramento Vegetal , RNA de Cadeia Dupla/metabolismo , Zea mays/genética , Zea mays/metabolismo
18.
Appl Environ Microbiol ; 88(8): e0203021, 2022 04 26.
Artigo em Inglês | MEDLINE | ID: mdl-35389250

RESUMO

Yeast killer toxins are widely distributed in nature, conferring a competitive advantage to the producer yeasts over nonkiller ones when nutrients are scarce. Most of these toxins are encoded on double-stranded RNAs (dsRNAs) generically called M. L-A members of the viral family Totiviridae act as helper viruses to maintain M, providing the virion proteins that separately encapsidate and replicate L-A and M genomes. M genomes are organized in three regions, a 5' region coding the preprotoxin, followed by an internal poly(A) stretch and a 3' noncoding region. In this work, we report the characterization of K74 toxin encoded on M74 dsRNA from Saccharomyces paradoxus Q74.4. In M74, there is a 5' upstream sequence of 141 nucleotides (nt), which contains regulatory signals for internal translation of the preprotoxin open reading frame (ORF) at the second AUG codon. The first AUG close to the 5' end is not functional. For K74 analysis, M74 viruses were first introduced into laboratory strains of Saccharomyces cerevisiae. We show here that the mature toxin is an α/ß heterodimer linked by disulfide bonds. Though the toxin (or preprotoxin) confers immunity to the carrier, cells with increased K74 loads have a sick phenotype that may lead to cell death. Thus, a fine-tuning of K74 production by the upstream regulatory sequence is essential for the host cell to benefit from the toxin it produces and, at the same time, to safely avoid damage by an excess of toxin. IMPORTANCE Killer yeasts produce toxins to which they are immune by mechanisms not well understood. This self-immunity, however, is compromised in certain strains, which secrete an excess of toxin, leading to sick cells or suicidal phenotypes. Thus, a fine-tuning of toxin production has to be achieved to reach a balance between the beneficial effect of toxin production and the stress imposed on the host metabolism. K74 toxin from S. paradoxus is very active against Saccharomyces uvarum, among other yeasts, but an excess of toxin production is deleterious for the host. Here, we report that the presence of a 5' 141-nt upstream sequence downregulates K74 toxin precursor translation, decreasing toxin levels 3- to 5-fold. Thus, this is a special case of translation regulation performed by sequences on the M74 genome itself, which have been presumably incorporated into the viral RNA during evolution for that purpose.


Assuntos
RNA de Cadeia Dupla , Saccharomyces cerevisiae , Humanos , Fatores Matadores de Levedura/genética , RNA de Cadeia Dupla/genética , RNA de Cadeia Dupla/metabolismo , Saccharomyces , Saccharomyces cerevisiae/genética , Regiões não Traduzidas
19.
Front Immunol ; 13: 861007, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35371040

RESUMO

Circular DNAs derived from single-stranded RNA viruses play important roles in counteracting viral infection. However, whether double-stranded RNA viruses generate functional circular DNAs is still unknown. Using circDNA sequencing, divergent PCR, DNA in situ hybridization and rolling circular amplification, we presently confirmed that in silkworm, Bombyx mori cytoplasmic polyhedrosis virus (BmCPV), a double-stranded RNA virus belonging to cypovirus, is prone to produce a BmCPV-derived circular DNA termed as vcDNA-S7. We have also found that vcDNA-S7 formation is mediated by endogenous reverse transcriptase (RT), and the proliferation of BmCPV can be inhibited by vcDNA-S7 in vitro and in vivo. Moreover, we have discovered that the silkworm RNAi immune pathway is activated by vcDNA-S7, while viral small interfering RNAs (vsiRNAs) derived from transcribed RNA by vcDNA-S7 can be detected by small RNA deep sequencing. These results suggest that BmCPV-derived vcDNA-S7, mediated by RT, can serve as a template for the biogenesis of antiviral siRNAs, which may lead to the repression of BmCPV infection. To our knowledge, this is the first demonstration that a circular DNA, produced by double stranded RNA viruses, is capable of regulating virus infection.


Assuntos
Bombyx , Reoviridae , Animais , DNA Circular , Interações Hospedeiro-Patógeno , RNA de Cadeia Dupla/metabolismo , DNA Polimerase Dirigida por RNA/genética , DNA Polimerase Dirigida por RNA/metabolismo , Reoviridae/fisiologia
20.
Int J Biol Macromol ; 209(Pt A): 1179-1187, 2022 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-35461859

RESUMO

To date, some DNA viruses and single-stranded RNA viruses have been found to generate circRNAs. However, the reports on circRNAs produced by double-stranded RNA viruses are very limited. In this study, Bombyx mori cypovirus (BmCPV), a typical double-stranded RNA virus belonging to the Reoviridae, was demonstrated to generate viral circRNAs (vcircRNAs) and a vcircRNA_000048 whose sequence corresponds with the region 164-1245 nt on the BmCPV genomic dsRNA S5 segment (GQ294468.1) was validated by PCR, Sanger sequencing, reverse transcription-rolling circle amplification, and Northern blotting. Furthermore, we verified that vcircRNA_000048 translates a micropeptide vsp21 with 21 amino acid residues in an IRES-dependent manner, and vsp21 attenuates the viral replication. These findings provided a novel clue to understanding the regulation of viral multiplication and interaction of reovirus with the host.


Assuntos
Bombyx , Reoviridae , Animais , Bombyx/genética , Interações Hospedeiro-Patógeno , RNA Circular/genética , RNA de Cadeia Dupla/metabolismo , RNA Viral/genética , RNA Viral/metabolismo , Reoviridae/genética , Reoviridae/metabolismo , Replicação Viral/genética
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