scholarly journals An Endogenous Retroviral LTR-Derived Long Noncoding RNA lnc-LTR5B Interacts With BiP to Modulate ALV-J Replication in Chicken Cells

2021 ◽  
Vol 12 ◽  
Author(s):  
Shihao Chen ◽  
Ruihan Zhao ◽  
Ting Wu ◽  
Dedong Wang ◽  
Biao Wang ◽  
...  
Keyword(s):  
Life Cycle ◽  
Cell Surface ◽  
Noncoding Rna ◽  
Regulatory Machinery ◽  
Infected Cells ◽  
Survival Signaling ◽  
Subgroup J ◽  
Avian Leukosis Virus Subgroup ◽  
Physical Availability ◽  
Host Genes

Infection with the avian leukosis virus subgroup J (ALV-J) impairs host genes and facilitates the establishment of chronic infection and the viral life cycle. However, the involvement of long noncoding RNAs (lncRNAs) in ALV-J infection remains largely unknown. In this study, we identified a novel chicken lncRNA derived from LTR5B of the ERV-L family (namely lnc-LTR5B), which is significantly downregulated in ALV-J infected cells. lnc-LTR5B was localized in the cytoplasm and was relatively high expressed in the chicken lung and liver. Notably, the replication of ALV-J was inhibited by the overexpression of lnc-LTR5B but enhanced when lnc-LTR5B expression was knocked down. We further confirmed that lnc-LTR5B could bind to the binding immunoglobulin protein (BiP), a master regulator of endoplasmic reticulum (ER) function. Mechanistically, lnc-LTR5B serves as a competing endogenous RNA for BiP, restricting its physical availability. Upon ALV-J infection, the reduction of lnc-LTR5B released BiP, which facilitated its translocation to the cell surface. This is crucial for ALV-J entry as well as pro-survival signaling. In conclusion, we identified an endogenous retroviral LTR-activated lnc-LTR5B that is involved in regulating the cell surface translocation of BiP, and such regulatory machinery can be exploited by ALV-J to complete its life cycle and propagate.

scholarly journals Role of Virally-Encoded Deubiquitinating Enzymes in Regulation of the Virus Life Cycle

2021 ◽  
Vol 22 (9) ◽  
pp. 4438
Author(s):  
Jessica Proulx ◽  
Kathleen Borgmann ◽  
In-Woo Park
Keyword(s):  
Immune Response ◽  
Life Cycle ◽  
Deubiquitinating Enzyme ◽  
Deubiquitinating Enzymes ◽  
Antiviral Immune Response ◽  
Cellular Processes ◽  
Virus Life Cycle ◽  
Infected Cells ◽  
Dependent Processes

The ubiquitin (Ub) proteasome system (UPS) plays a pivotal role in regulation of numerous cellular processes, including innate and adaptive immune responses that are essential for restriction of the virus life cycle in the infected cells. Deubiquitination by the deubiquitinating enzyme, deubiquitinase (DUB), is a reversible molecular process to remove Ub or Ub chains from the target proteins. Deubiquitination is an integral strategy within the UPS in regulating survival and proliferation of the infecting virus and the virus-invaded cells. Many viruses in the infected cells are reported to encode viral DUB, and these vial DUBs actively disrupt cellular Ub-dependent processes to suppress host antiviral immune response, enhancing virus replication and thus proliferation. This review surveys the types of DUBs encoded by different viruses and their molecular processes for how the infecting viruses take advantage of the DUB system to evade the host immune response and expedite their replication.

scholarly journals Interaction of Pestiviral E1 and E2 Sequences in Dimer Formation and Intracellular Retention

2021 ◽  
Vol 22 (14) ◽  
pp. 7285
Author(s):  
Yu Mu ◽  
Birke Andrea Tews ◽  
Christine Luttermann ◽  
Gregor Meyers
Keyword(s):  
Life Cycle ◽  
Cell Surface ◽  
Double Mutant ◽  
Essential Role ◽  
Infectious Clone ◽  
Intracellular Localization ◽  
Dimer Formation ◽  
Covalent Linkage ◽  
Crucial Step ◽  
Retention Signal

Pestiviruses contain three envelope proteins: Erns, E1, and E2. Expression of HA-tagged E1 or mutants thereof showed that E1 forms homodimers and -trimers. C123 and, to a lesser extent, C171, affected the oligomerization of E1 with a double mutant C123S/C171S preventing oligomerization completely. E1 also establishes disulfide linked heterodimers with E2, which are crucial for the recovery of infectious viruses. Co-expression analyses with the HA-tagged E1 wt/E1 mutants and E2 wt/E2 mutants demonstrated that C123 in E1 and C295 in E2 are the critical sites for E1/E2 heterodimer formation. Introduction of mutations preventing E1/E2 heterodimer formation into the full-length infectious clone of BVDV CP7 prevented the recovery of infectious viruses, proving that C123 in E1 and C295 in E2 play an essential role in the BVDV life cycle, and further support the conclusion that heterodimer formation is the crucial step. Interestingly, we found that the retention signal of E1 is mandatory for intracellular localization of the heterodimer, so that absence of the E1 retention signal directs the heterodimer to the cell surface even though the E2 retention signal is still present. The covalent linkage between E1 and E2 plays an essential role for this process.

scholarly journals Genome-Wide Expression Patterns of Rhoptry Kinases during the Eimeria tenella Life-Cycle

2021 ◽  
Vol 9 (8) ◽  
pp. 1621
Author(s):  
Adeline Ribeiro E Silva ◽  
Alix Sausset ◽  
Françoise I. Bussière ◽  
Fabrice Laurent ◽  
Sonia Lacroix-Lamandé ◽  
...  
Keyword(s):  
Life Cycle ◽  
Expression Patterns ◽  
Housekeeping Genes ◽  
Catalytic Triad ◽  
Eimeria Tenella ◽  
Apicomplexan Parasites ◽  
Genome Wide ◽  
Infected Cells ◽  
First And Second Generation

Kinome from apicomplexan parasites is composed of eukaryotic protein kinases and Apicomplexa specific kinases, such as rhoptry kinases (ROPK). Ropk is a gene family that is known to play important roles in host–pathogen interaction in Toxoplasma gondii but is still poorly described in Eimeria tenella, the parasite responsible for avian coccidiosis worldwide. In the E. tenella genome, 28 ropk genes are predicted and could be classified as active (n = 7), inactive (incomplete catalytic triad, n = 12), and non-canonical kinases (active kinase with a modified catalytic triad, n = 9). We characterized the ropk gene expression patterns by real-time quantitative RT-PCR, normalized by parasite housekeeping genes, during the E. tenella life-cycle. Analyzed stages were: non-sporulated oocysts, sporulated oocysts, extracellular and intracellular sporozoites, immature and mature schizonts I, first- and second-generation merozoites, and gametes. Transcription of all those predicted ropk was confirmed. The mean intensity of transcription was higher in extracellular stages and 7–9 ropk were specifically transcribed in merozoites in comparison with sporozoites. Transcriptional profiles of intracellular stages were closely related to each other, suggesting a probable common role of ROPKs in hijacking signaling pathways and immune responses in infected cells. These results provide a solid basis for future functional analysis of ROPK from E. tenella.

scholarly journals Mutation of Putative N-Glycosylation Sites on Dengue Virus NS4B Decreases RNA Replication

2015 ◽  
Vol 89 (13) ◽  
pp. 6746-6760 ◽  
Author(s):  
Nenavath Gopal Naik ◽  
Huey-Nan Wu
Keyword(s):  
Life Cycle ◽  
Recombinant Protein ◽  
Dengue Virus ◽  
Protein Expression ◽  
Nonstructural Protein ◽  
Recombinant Protein Expression ◽  
Rna Replication ◽  
Viral Production ◽  
Glycosylation Sites ◽  
Infected Cells

ABSTRACTDengue virus (DENV) nonstructural protein 4B (NS4B) is an endoplasmic reticulum (ER) membrane-associated protein, and mutagenesis studies have revealed its significance in viral genome replication. In this work, we demonstrated that NS4B is an N-glycosylated protein in virus-infected cells as well as in recombinant protein expression. NS4B is N glycosylated at residues 58 and 62 and exists in two forms, glycosylated and unglycosylated. We manipulated full-length infectious RNA clones and subgenomic replicons to generate N58Q, N62Q, and N58QN62Q mutants. Each of the single mutants had distinct effects, but the N58QN62Q mutation resulted in dramatic reduction of viral production efficiency without affecting secretion or infectivity of the virion in mammalian and mosquito C6/36 hosts. Real-time quantitative PCR (qPCR), subgenomic replicon, andtrans-complementation assays indicated that the N58QN62Q mutation affected RNA replication possibly by the loss of glycans. In addition, four intragenic mutations (S59Y, S59F, T66A, and A137T) were obtained from mammalian and/or mosquito C6/36 cell culture systems. All of these second-site mutations compensated for the replication defect of the N58QN62Q mutant without creating novel glycosylation sites.In vivoprotein stability analyses revealed that the N58QN62Q mutation alone or plus a compensatory mutation did not affect the stability of NS4B. Overall, our findings indicated that mutation of putative N-glycosylation sites affected the biological function of NS4B in the viral replication complex.IMPORTANCEThis is the first report to identify and reveal the biological significance of dengue virus (DENV) nonstructural protein 4B (NS4B) posttranslation N-glycosylation to the virus life cycle. The study demonstrated that NS4B is N glycosylated in virus-infected cells and in recombinant protein expression. NS4B is modified by glycans at Asn-58 and Asn-62. Functional characterization implied that DENV NS4B utilizes the glycosylation machinery in both mammalian and mosquito hosts. Four intragenic mutations were found to compensate for replication and subsequent viral production deficiencies without creating novel N-glycosylation sites or modulating the stabilities of the protein, suggesting that glycans may be involved in maintaining the NS4B protein conformation. NS4B glycans may be necessary elements of the viral life cycle, but compensatory mutations can circumvent their requirement. This novel finding may have broader implications in flaviviral biology as the most likely glycan at Asn-62 of NS4B is conserved in DENV serotypes and in some related flaviviruses.

scholarly journals Natural Cytotoxicity Receptors: Pattern Recognition and Involvement of Carbohydrates

2005 ◽  
Vol 5 ◽  
pp. 151-154 ◽  
Author(s):  
Angel Porgador
Keyword(s):  
Pattern Recognition ◽  
Cell Membrane ◽  
Cell Surface ◽  
Innate Immune ◽  
Target Cells ◽  
Natural Cytotoxicity ◽  
Tumor Cell Membrane ◽  
Infected Cells ◽  
Natural Cytotoxicity Receptors ◽  
New Evidence

Natural cytotoxicity receptors (NCRs), expressed by natural killer (NK) cells, trigger NK lysis of tumor and virus-infected cells on interaction with cell-surface ligands of these target cells. We have determined that viral hemagglutinins expressed on the surface of virus-infected cells are involved in the recognition by the NCRs, NKp44 and NKp46. Recognition of tumor cells by the NCRs NKp30 and NKp46 involves heparan sulfate epitopes expressed on the tumor cell membrane. Our studies provide new evidence for the identity of the ligands for NCRs and indicate that a broader definition should be applied to pathological patterns recognized by innate immune receptors. Since nonmicrobial endogenous carbohydrate structures contribute significantly to this recognition, there is an imperative need to develop appropriate tools for the facile sequencing of carbohydrate moieties.

scholarly journals Cellular Zinc Finger Protein 622 Hinders Human Adenovirus Lytic Growth and Limits Binding of the Viral pVII Protein to Virus DNA

2018 ◽  
Vol 93 (3) ◽  
Author(s):  
Kwangchol Mun ◽  
Tanel Punga
Keyword(s):  
Life Cycle ◽  
Zinc Finger ◽  
Zinc Finger Protein ◽  
Human Adenovirus ◽  
Antiviral Protein ◽  
Viral Dna ◽  
Finger Protein ◽  
Wide Range ◽  
Infected Cells ◽  
Cellular Zinc

ABSTRACTHuman adenovirus (HAdV) encodes a multifunctional DNA-binding protein pVII, which is involved in virus DNA packaging and extracellular immune signaling regulation. Although the pVII is an essential viral protein, its exact role in the virus life cycle and interplay with cellular proteins have remained to a large extent unclear. We have recently identified the cellular zinc finger protein 622 (ZNF622) as a potential pVII-interacting protein. In this study, we describe the functional consequences of the ZNF622-pVII interplay and the role of ZNF622 in the HAdV life cycle. ZNF622 protein expression increased, and it accumulated similarly to the pVII protein in the nuclei of virus-infected cells. The lack of the ZNF622 protein specifically increased pVII binding to viral DNA in the infected cells and elevated the pVII protein levels in the purified virions. In addition, ZNF622 knockout cells showed an increased cell lysis and enhanced accumulation of the infectious virus particles. Protein interaction studies revealed that ZNF622 forms a trimeric complex with the pVII protein and the cellular histone chaperon protein nucleophosmin 1 (NPM1). The integrity of this complex is important since ZNF622 mutations and NPM1 deficiency changed pVII ability to bind viral DNA. Collectively, our results implicate that ZNF622 may act as a cellular antiviral protein hindering lytic HAdV growth and limiting pVII protein binding to viral DNA.IMPORTANCEHuman adenoviruses (HAdVs) are common human pathogens causing a wide range of acute infections. To counteract viral pathogenicity, cells encode a variety of antiviral proteins and noncoding RNAs to block virus growth. In this study, we show that the cellular zinc finger protein 622 (ZNF622) interacts with an essential HAdV protein known as pVII. This mutual interaction limits pVII binding to viral DNA. Further, ZNF622 has a role in HAdV life cycle since the lack of ZNF622 correlates with increased lysis of the infected cells and accumulation of the infectious virions. Together, our study reveals a novel cellular antiviral protein ZNF622, which may impede lytic HAdV growth.

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