• The Plant Pathology Journal
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• 제20권1호
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• pp.22-29
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• 2004

Many important horticultural and field crops are susceptible to virus infections or may possess a degree of resistance to some viruses, but become infected by others. Plant viruses enter cells through the presence of wounds, and replicate intracellularly small genomes that encode genes required for replication, cell-to-cell movement and encapsidation. There are numerous evidences from specific virus-host interactions to require the involvement of host factors and steps during viral replication cycle. However, viruses should deal with host defense responses either by general or specific mechanisms, targeting viral components or genome itself. On the other hand, the host plants have also adapted to defend themselves against viral attack by operating different lines of resistance responses. The defense-related interactions provide new insights into the complex molecular strategies for hosts for defense and counter-defense employed by viruses.

• Asian Pacific Journal of Cancer Prevention
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• 제13권4호
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• pp.1297-1303
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• 2012

Aims: Primary hepatocellular carcinoma (HCC) is a common malignancy often related to hepatitis viral infection. Smad4 is known to mediate the TGF-${\beta}$ pathway to suppress tumorigenesis. However, the function of Smad4 in HCC is still controversial. In this study we compared levels of Smad4 in HCC tissues with or without hepatitis virus infection and adjacent normal-appearing liver. Methods: Samples from HCC patients were analyzed for Smad4 protein and mRNA expression by immunohistochemistry (IHC), RT-PCR and Western blotting. Results: We found that tumor tissues expressed less Smad4 mRNA and protein than the adjacent tissues. Most HCC tumor tissues were negative for Smad4 in IHC staining, while the majority of adjacent tissues were positively stained. Interestingly, protein levels were higher in HCC tissues with viral hepatitis than those without virus infection. Suppression of expression appeared closely related to HCC, so that Smad4 appears to function as a tumor suppressor gene (TSG). Conclusion: Patients with hepatitis viral infection, at higher risk for HCC, exhibited increased Smad4 protein expression suggesting hepatitis virus may modulate Smad4 expression, which is functionally distinct from its putative role as a TSG. Smad4 expression may thus be an applicable marker for diagnosis and/or a target to develop therapeutic agents for HCC.

• Environmental Analysis Health and Toxicology
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• 제19권3호
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• pp.321-326
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• 2004

The study of p53 tumor suppressor protein is one of most important subjects in an environmental toxicology as well as in cancer biology. Generally, p53 has been known to involve the cell cycle regulation and apoptosis by the activation of its target genes such as p21 and bax in a number of cellular stress responses. In addition, associations of p53 with cellular proteins presumably reflect the involvement of p53 in critical cellular processes such as DNA repair. The complex formation of p53 and exogenous proteins such as viral or cellular proteins has been shown in many cases to play important roles in carcinogenic processes against environmental mutagen. Recently, the disruption of p53 protein by oxidative stress has been also reported to have relevance to carcinogenesis. These findings suggested that the maintaining of stability and functional activity of p53 protein was also important aspect to play as a tumor suppressor protein. Therefore, the detection of functional status of p53 proteins might be an effective biomarker for the cancer and human diseases under the environmental toxicologic carcinogen.

• Genomics & Informatics
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• 제13권2호
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• pp.26-30
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• 2015

nc886 (=vtRNA2-1, pre-miR-886, or CBL3) is a newly identified non-coding RNA (ncRNA) that represses the activity of protein kinase R (PKR). nc886 is transcribed by RNA polymerase III (Pol III) and is intriguingly the first case of a Pol III gene whose expression is silenced by CpG DNA hypermethylation in several types of cancer. PKR is a sensor protein that recognizes evading viruses and induces apoptosis to eliminate infected cells. Like viral infection, nc886 silencing activates PKR and induces apoptosis. Thus, the significance of the nc886:PKR pathway in cancer is to sense and eliminate pre-malignant cells, which is analogous to PKR's role in cellular innate immunity. Beyond this tumor sensing role, nc886 plays a putative tumor suppressor role as supported by experimental evidence. Collectively, nc886 provides a novel example how epigenetic silencing of a ncRNA contributes to tumorigenesis by controlling the activity of its protein ligand.

• IMMUNE NETWORK
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• 제10권3호
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• pp.104-108
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• 2010

CD137 (4-1BB/tnfrsf9) has been shown to co-stimulate T cells. However, agonistic anti-CD137 monoclonal antibody (mAb) treatment can suppress $CD4^+$ T cells, ameliorating autoimmune diseases, whereas it induces activation of $CD8^+$ T cells, resulting in diverse therapeutic activity in cancer, viral infection. To investigate the CD137-mediated T cell suppression mechanism, we examined whether anti-CD137 mAb treatment could affect $CD11b^+Gr-1^+$ myeloid-derived suppressor cells (MDSCs). Intriguingly, anti-CD137 mAb injection significantly increased $CD11b^+Gr-1^+$ cells, peaking at days 5 to 10 and continuing for at least 25 days. Furthermore, this cell population could suppress both $CD8^+$ T cells and $CD4^+$ T cells. Thus, this study demonstrated that, for the first time, anti-CD137 mAb treatment could induce $CD11b^+Gr-1^+$ MDSCs under normal conditions, suggesting a possible relationship between myeloid cell induction and CD137-mediated immune suppression.

• 농업과학연구
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• 제44권2호
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• pp.145-180
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• 2017

Alternanthera mosaic virus (AltMV) is a member of the genus Potexvirus which has been known for less than twenty years, and has been detected in Australasia, Europe, North and South America, and Asia. The natural host range to date includes species in at least twenty-four taxonomically diverse plant families, with species in at least four other families known to be infected experimentally. AltMV has been shown to differ from Potato virus X (PVX), the type member of the genus Potexvirus, in a number of ways, including the subcellular localization of the Triple Gene Block 3 (TGB3) protein and apparent absence of interactions between TGB3 and TGB2. Differences between AltMV variants have allowed identification of viral determinants of pathogenicity, and identification of residues involved in interactions with host proteins. Infectious clones of AltMV differing significantly in symptom severity and efficiency of RNA silencing suppression have been produced, suitable either for high level protein expression (with efficient RNA silencing suppression) or for Virus-Induced Gene Silencing (VIGS; with weaker RNA silencing suppression), demonstrating a range of utility not available with most other plant viral vectors. The difference in silencing suppression efficiency was shown to be due to a single amino acid residue substitution in TGB1, and to differences in subcellular localization of TGB1 to the nucleus and nucleolus. The current state of knowledge of AltMV biology, including host range, strain differentiation, host interactions, and utility as a plant viral vector for both protein expression and VIGS are summarized.

• BMB Reports
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• 제41권10호
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• pp.739-744
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• 2008

Turnip yellow mosaic virus (TYMV) is a positive strand RNA virus that infects mainly Cruciferae plants. In this study, the TYMV genome was modified by inserting an extra subgenomic RNA promoter and a multiple cloning site. This modified TYMV was introduced into Nicotiana benthamiana using a Agrobacterium-mediated T-DNA transfer system (agroinfiltration). When a gene encoding $\beta$-glucuronidase or green fluorescent protein was expressed using this modified TYMV as a vector, replication of the recombinant viruses, especially the virus containing $\beta$-glucuronidase gene, was severely inhibited. The suppression of replication was reduced by co-expression of viral silencing suppressor genes, such as tombusviral p19, closteroviral p21 or potyviral HC-Pro. As expected, two subgenomic RNAs were produced from the recombinant TYMV, where the larger one contained the foreign gene. An RNase protection assay revealed that the recombinant subgenomic RNA was encapsidated as efficiently as the genuine subgenomic RNA.

• International Journal of Industrial Entomology and Biomaterials
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• 제12권2호
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• pp.57-61
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• 2006

Suppressor of cytokine signaling (SOCS) is known to be as a negative feedback regulator in Janus kinase signal transducer and activator of transcription signaling. Highly conserved SOCS box domain was cloned from a Korean malaria vector, Anopheles sinensis. Sequence analysis indicates that it has identity to Anopheles gambiae (96%), Aedes aegypti (94%), Drosophila melanogaster (78%), Mus musculus (72%) and Homo sapiens (72%), respectively. Tissue specificity RT-PCR demonstrated that the expression level of AsSOCS transcript was high at abdomen, midgut, and ovary, whereas developmental expression patterns showed that the level of AsSOCS was high at egg, early pupae, and adult female. On the other hand, RT-PCR analysis after bacterial challenge showed that SOCS mRNA was strongly induced in larvae. In addition, it was also induced by various immune elicitors such as lipoteicoic acid, CpG-DNA, and laminarin. It seems that AsSOCS, repressor of JAK-STAT pathway, is highly conserved in mosquito, and may play an important role in mosquito innate immune response.

• The Plant Pathology Journal
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• 제27권4호
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• pp.315-323
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• 2011

Soybean plants infected with Bean pod mottle virus (BPMV) develop acute symptoms that usually decrease in severity over time. In other plant-virus interactions, this type of symptom recovery has been associated with degradation of viral RNAs by RNA silencing, which is accompanied by the accumulation of virus-derived small interfering RNAs (siRNAs). In this study, changes in the accumulation of BPMV siRNAs were investigated in soybean plants infected with BPMV alone, or infected with both BPMV and Soybean mosaic virus (SMV) and in transgenic soybean plants expressing SMV helper component-protease (HC-Pro). In many potyviruses, HC-Pro is a potent suppressor of RNA silencing. In plants infected with BPMV alone, accumulation of siRNAs was positively correlated with symptom severity and accumulation of BPMV genomic RNAs. Plants infected with both BPMV and SMV and BPMV-infected transgenic soybean plants expressing SMV HC-Pro exhibited severe symptoms characteristic of BPMVSMV synergism, and showed enhanced accumulation of BPMV RNAs and siRNAs compared to plants infected with BPMV alone and nontransgenic plants. Likewise, SMV HC-Pro enhanced the accumulation of siRNAs produced from a silenced green fluorescent protein gene in transient expression assays, while the P19 silencing suppressor of Tomato bushy stunt virus did not. Consistent with the modes of action of HC-Pro in other systems, which have shown that HC-Pro suppresses RNA silencing by preventing the unwinding of duplex siRNAs and inhibiting siRNA methylation, these studies showed that SMV HC-Pro interfered with the activities of RNA-induced silencing complexes, but not the activities of Dicer-like enzymes in antiviral defenses.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 1994년도 춘계학술대회 and 제3회 신약개발 연구발표회
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• pp.178-178
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• 1994

Hepatitis B Virus (HBV) is a DNA virus with a 3.2kb partially double-stranded genome. The life cycle of the virus involves a reverse transcription of the greater than genome length 3.5kb mRNA. This pegenomic RNA contains all the genetic information encoded by the virus and functions as an intermediate in viral replication. Tumor suppressor p53 has previously been shown to interact with the X-gene product of the HBV, which led us to hypothesize that p53 may act as a negative regulator of HBV replication and the role of the X-gene product is to overcome the p53-mediated restriction. As a first step to prove the above hypothesis, we tested whether p53 represses the propagation of HBV in in vitro replication system. By transient cotransfection of the plasmid containing a complete copy of the HBV genome and/or the plasmid encoding p53, we found that the replication of HBV is specifically blocked by wild-type p53. The levels of HBV DNA, HBs Ag and HBc/e Ag secreted in cell culture media were dramatically reduced upon coexpresion of wild-type p53 but not by the coexpression of the mutants of p53 (G154V and R273L). Furthermore, levels of RNAs originated from HBV genome were repressed more than 10 fold by the cotransfection of the p53 encoding plasmid. These results clearly states that p53 is a nesative regulator of the HBV replication. Next, to addresss the mechanism by which p53 represses the HBV replication, we performed the transient transfection experiments employing the pregenomic/core promoter-CAT(Chloramphenicol Acetyl Transferase) construct as a reporter. Cotransfection of wild-type p53 but not the mutant p53 expression plasmids repressed the CAT activity more than 8 fold. Integrating the above results, we propose that p53 represses the replication of HBV specifically by the down-regulation of the pregenomic/core promoter, which results in the reduced DNA synthesis of HBV. Currently, the mechanism by which HBV overcomes the observed p53-mediated restriction of replication is tinder investigation.