DeSUMOylation of Apoptosis Inhibitor 5 by Avibirnavirus VP3 Supports Virus Replication

Evidence of immunogenic cell death as a predictor of response to cancer therapy has increased interest in the high molecular group box 1 protein (HMGB1). HMGB1 is a nuclear protein associated with chromatin organization and DNA damage repair. HMGB1 is also a damage-associated molecular pattern (DAMP) protein and promotes proinflammatory signaling in a paracrine and autocrine manner. Extracellular HMGB1 can promote activation of NF-kB and is associated with several chronic inflammatory and autoimmune diseases, including sepsis, rheumatoid arthritis, atherosclerosis, chronic kidney disease, systemic lupus erythematosus (SLE), as well as cancer. In this review, we describe studies that demonstrate the use of deacetylase inhibitors and HMGB1 inhibitors to alter the expression and localization of HMGB1 in cancer cells, with a focus on lung cancer. The drugs described herein are well established and frequently used in human and small mammal studies. The main objective of this review is to summarize the potential benefit of targeting posttranslational modification of HMGB1 to decrease inflammatory signaling in the tumor microenvironment, and perhaps lead to improved response to current immunotherapeutic approaches.

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E1B-55-Kilodalton Protein Is Not Required To Block p53-Induced Transcription during Adenovirus Infection

Journal of Virology ◽

10.1128/jvi.78.14.7685-7697.2004 ◽

2004 ◽

Vol 78 (14) ◽

pp. 7685-7697 ◽

Cited By ~ 31

Author(s):

Urs Hobom ◽

Matthias Dobbelstein

Keyword(s):

Virus Replication ◽

Target Genes ◽

Mutational Analysis ◽

P300 Binding ◽

Reporter Assays ◽

Direct Binding ◽

Infected Cells ◽

Adenovirus E1b ◽

Apoptosis Inhibitor ◽

P53 Target Genes

ABSTRACT The adenovirus E1B-55-kDa protein binds and inactivates the tumor suppressor protein p53. However, the role of this interaction during infection is still poorly understood and was therefore examined here. Infection with a virus carrying the E1B-55-kDa mutation R239A, preventing the interaction with p53, led to the accumulation of p53. However, p53 target genes were not activated in the infected cells, although p53 phosphorylation did occur and the p53 antagonists Mdm2 and ΔNp73 did not accumulate. Deletion of E4orf6, alone or in combination with E1B-55-kDa, did not allow the induction of p53-responsive genes either. In transient reporter assays, the viral E1A-13S protein antagonized p53 activity; mutational analysis suggested that this depends partially on p300 binding, but it depends even more strongly on the interaction of E1A with the p400/TRRAP protein complex. However, viruses expressing E1A mutants lacking these binding activities, in combination with E1B-55-kDa R239A, still abolished p53 activity. In contrast, when the mutation of E1B-55-kDa at R239A was combined with a deletion of the apoptosis inhibitor E1B-19-kDa, infected cells showed more extensive apoptosis than after infection with single mutants, suggesting that accumulated p53, albeit transcriptionally inactive, might nonetheless enhance apoptosis. Despite extensive apoptosis of the infected cells, the deletion of E1B-19-kDa, in combination with the E1B-55-kDa mutation or in the presence of the constitutively active p53 mutant p53mt24-28, reduced virus replication less than fivefold. In conclusion, adenovirus does not need direct binding of E1B-55-kDa to inactivate p53, and forced p53 activity with consecutive apoptosis does not severely impair virus replication.

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The rat cytomegalovirus homologue of parvoviral rep genes, r127, encodes a nuclear protein with single- and double-stranded DNA-binding activity that is dispensable for virus replication

Journal of General Virology ◽

10.1099/vir.0.79864-0 ◽

2004 ◽

Vol 85 (7) ◽

pp. 2001-2013 ◽

Cited By ~ 6

Author(s):

Koen W. R. van Cleef ◽

Wendy M. A. Scaf ◽

Karen Maes ◽

Suzanne J. F. Kaptein ◽

Erik Beuken ◽

...

Keyword(s):

Dna Binding ◽

Virus Replication ◽

Deletion Mutant ◽

Nuclear Protein ◽

Human Herpesvirus ◽

Binding Activity ◽

Dna Binding Activity ◽

Double Stranded Dna

An intriguing feature of the rat cytomegalovirus (RCMV) genome is open reading frame (ORF) r127, which shows similarity to the rep genes of parvoviruses as well as the U94 genes of human herpesvirus type 6A (HHV-6A) and 6B (HHV-6B). Counterparts of these genes have not been found in other herpesviruses. Here, it is shown that the r127 gene is transcribed during the early and late phases of virus replication in vitro as an unspliced 1·1 kb transcript containing the complete r127 ORF. Transcripts of r127 were also detected in various organs of RCMV-infected rats at 1 week post-infection (p.i.), but only in the salivary gland at 4 months p.i. Using rabbit polyclonal antibodies raised against the r127-encoded protein (pr127), pr127 was found to be expressed as early as 12 h p.i. within the nuclei of RCMV-infected cells in vitro. Expression of pr127 was also observed within the nuclei of cells in various organs of RCMV-infected rats at 3 weeks p.i. Moreover, pr127 was demonstrated to bind single- as well as double-stranded DNA. Finally, an RCMV r127 deletion mutant (RCMVΔr127) was generated, in which the r127 ORF was disrupted. This deletion mutant, however, was shown to replicate with a similar efficiency as wild-type RCMV (wt RCMV), both in vitro and in vivo. Taken together, it is concluded that the RCMV r127 gene encodes a nuclear protein with single- and double-stranded DNA-binding activity that is dispensable for virus replication, not only in vitro, but also during the acute phase of infection in vivo.

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ADP-ribosyl–binding and hydrolase activities of the alphavirus nsP3 macrodomain are critical for initiation of virus replication

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1812130115 ◽

2018 ◽

Vol 115 (44) ◽

pp. E10457-E10466 ◽

Cited By ~ 27

Author(s):

Rachy Abraham ◽

Debra Hauer ◽

Robert Lyle McPherson ◽

Age Utt ◽

Ilsa T. Kirby ◽

...

Keyword(s):

Virus Replication ◽

Posttranslational Modification ◽

Infectious Virus ◽

Nonstructural Protein ◽

Hydrolase Activity ◽

Host Protein ◽

Chikv Infection ◽

Adp Ribosylation ◽

Host Protein Synthesis ◽

Established Infection

Alphaviruses are plus-strand RNA viruses that cause encephalitis, rash, and arthritis. The nonstructural protein (nsP) precursor polyprotein is translated from genomic RNA and processed into four nsPs. nsP3 has a highly conserved macrodomain (MD) that binds ADP-ribose (ADPr), which can be conjugated to protein as a posttranslational modification involving transfer of ADPr from NAD+by poly ADPr polymerases (PARPs). The nsP3MDalso removes ADPr from mono ADP-ribosylated (MARylated) substrates. To determine which aspects of alphavirus replication require nsP3MDADPr-binding and/or hydrolysis function, we studied NSC34 neuronal cells infected with chikungunya virus (CHIKV). Infection induced ADP-ribosylation of cellular proteins without increasing PARP expression, and inhibition of MARylation decreased virus replication. CHIKV with a G32S mutation that reduced ADPr-binding and hydrolase activities was less efficient than WT CHIKV in establishing infection and in producing nsPs, dsRNA, viral RNA, and infectious virus. CHIKV with a Y114A mutation that increased ADPr binding but reduced hydrolase activity, established infection like WT CHIKV, rapidly induced nsP translation, and shut off host protein synthesis with reduced amplification of dsRNA. To assess replicase function independent of virus infection, a transreplicase system was used. Mutant nsP3MDs D10A, G32E, and G112E with no binding or hydrolase activity had no replicase activity, G32S had little, and Y114A was intermediate to WT. Therefore, ADP ribosylation of proteins and nsP3MDADPr binding are necessary for initiation of alphavirus replication, while hydrolase activity facilitates amplification of replication complexes. These observations are consistent with observed nsP3MDconservation and limited tolerance for mutation.

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Two Putative Cypovirus-Encoded miRNAs Co-regulate the Host Gene of GTP-Binding Nuclear Protein Ran and Facilitate Virus Replication

Frontiers in Physiology ◽

10.3389/fphys.2021.663482 ◽

2021 ◽

Vol 12 ◽

Author(s):

Su Lin ◽

Yongsheng Wang ◽

Ze Zhao ◽

Wanming Wu ◽

Yun Su ◽

...

Keyword(s):

Gene Expression ◽

Virus Replication ◽

Target Gene ◽

Nuclear Protein ◽

The Body ◽

Host Gene ◽

Genomic Rnas ◽

Gtp Binding ◽

Effective Multiplication ◽

Bmn Cells

microRNA (miRNA) plays important roles in regulating various biological processes, including host-pathogen interaction. Recent studies have demonstrated that virus-encoded miRNAs can manipulate host gene expression to ensure viral effective multiplication. Bombyx mori cypovirus (BmCPV), a double-stranded RNA virus with a segmented genome, is one of the important pathogens for the economically important insect silkworm. Our present study indicated that two putative miRNAs encoded by BmCPV could promote viral replication by inhibiting the gene expression of B. mori GTP-binding nuclear protein Ran (BmRan), an essential component of the exportin-5-mediated nucleocytoplasmic transport of small RNAs. BmCPV-miR-1 and BmCPV-miR-3 are two of the BmCPV-encoded miRNAs identified in our previous studies. BmRan is a common target gene of them with binding sites all located in the 3′-untranslated region (3′-UTR) of its mRNA. The expression levels of the two miRNAs in the midgut of larvae infected with BmCPV gradually increased with the advance of infection, while the expression of the target gene BmRan decreased gradually. The miRNAs and the recombinant target gene consisting of reporter gene mCherry and 3′-UTR of BmRan mRNA were expressed in HEK293T cells for validating the interaction between the miRNAs and the target gene. qRT-PCR results revealed that BmCPV-miR-1 and BmCPV-miR-3 negatively regulate target gene expression not only separately but also cooperatively by binding to the 3′-UTR of BmRan mRNA. By transfecting miRNA mimics into BmN cells and injecting the mimics into the body of silkworm larvae, it was indicated that both BmCPV-miR-1 and BmCPV-miR-3 could repress the expression of BmRan in BmN cells and in the silkworm, and the cooperative action of the two miRNAs could enhance the repression of BmRan expression. Furthermore, the repression of BmRan could facilitate the replication of BmCPV genomic RNAs. It is speculated that BmCPV-miR-1 and BmCPV-miR-3 might reduce the generation of host miRNAs by inhibiting expression of BmRan, thus creating a favorable intracellular environment for virus replication. Our results are helpful to better understand the pathogenic mechanism of BmCPV to the silkworm, and provide insights into one of the evasion strategies used by viruses to counter the host defense for their effective multiplication.

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Neurofilaments and Paired Helical Filaments

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100120357 ◽

1985 ◽

Vol 43 ◽

pp. 740-743

Author(s):

J. Metuzals

Keyword(s):

Animal Model ◽

Posttranslational Modifications ◽

Posttranslational Modification ◽

Giant Axon ◽

Paired Helical Filaments ◽

Squid Giant Axon ◽

In Vitro Experiments ◽

Thin Sections ◽

Structural Relationships

It has been demonstrated that the neurofibrillary tangles in biopsies of Alzheimer patients, composed of typical paired helical filaments (PHF), consist also of typical neurofilaments (NF) and 15nm wide filaments. Close structural relationships, and even continuity between NF and PHF, have been observed. In this paper, such relationships are investigated from the standpoint that the PHF are formed through posttranslational modifications of NF. To investigate the validity of the posttranslational modification hypothesis of PHF formation, we have identified in thin sections from frontal lobe biopsies of Alzheimer patients all existing conformations of NF and PHF and ordered these conformations in a hypothetical sequence. However, only experiments with animal model preparations will prove or disprove the validity of the interpretations of static structural observations made on patients. For this purpose, the results of in vitro experiments with the squid giant axon preparations are compared with those obtained from human patients. This approach is essential in discovering etiological factors of Alzheimer's disease and its early diagnosis.

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