• 한국동물위생학회지
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• 제44권4호
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• pp.195-207
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• 2021

Species A rotaviruses (RVAs) replicate and assemble their immature particles within electron dense compartments known as viroplasms, where lipid droplets (LDs) interact with the viroplasm and facilitate viral replication. Despite the importance of LD formation in the life cycle of RVAs, the upstream molecules modulating LD formation remain unclear. This study aimed to find out the role of sterol regulatory element-binding proteins (SREBPs) in reprogramming of LD formation after RVA infection. Here, we demonstrate that RVA infection reprograms the sterol regulatory element-binding proteins (SREBPs)-dependent lipogenic pathways in virus-infected cells, and that both SREBP-1 and -2 transactivated genes, which are involved in fatty acid and cholesterol biosynthesis, are essential for LD formation. Our results showed that pharmacological inhibition of SREBPs using AM580 and betulin and inhibition of their downstream cholesterol biosynthesis (simvastatin for HMG-CoA reductase) and fatty acid enzymes (TOFA) negatively modulated the intracellular triacylglycerides and cholesterol levels and their resulting LD and viroplasm formations. Interestingly, pharmacological inhibition of SREBPs significantly reduced RVA protein synthesis, genome replication and progeny production. This study identified SREBPs-mediated lipogenic reprogramming in RVA-infected host cells, which facilitates virus replication through LD formation and its interaction with viroplasms, suggesting that SREBPs can be a potential target for the development of efficient and affordable therapeutics against RVA infection.

• Journal of Microbiology
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• 제42권4호
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• pp.361-364
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• 2004

Internal ribosome entry site (IRES) of the hepatitis C virus (HCV) is known to be essential for HCV replication and most conserved among HCV variants. Hence, IRES RNA is a good therapeutic target for RNA-based inhibitors, such as ribozymes. We previously proposed a new anti-HCV modulation strategy based on trans-splicing ribozymes, which can selectively replace HCV transcripts with a new RNA that exerts anti-HCV activity. To explore this procedure, sites which are accessible to ribozymes in HCV IRES were previously determined by employing an RNA mapping method in vitro. In this study, we evaluate the intracellular accessibility of the ribozymes by comparing the trans-splicing activ­ities in cells of several ribozymes targeting different sites of the HCV IRES RNA. We assessed the intra­cellular activities of the ribozymes by monitoring their target-specific induction degree of both reporter gene activity and cytotoxin expression. The ribozyme capable of targeting the most accessible site iden­tified by the mapping studies then harbored the most active trans-splicing activity in cells. These results suggest that the target sites predicted to be accessible are truly the most accessible in the cells, and thus, could be applied to the development of various RNA-based anti-HCV therapies.

• Parasites, Hosts and Diseases
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• 제54권2호
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• pp.139-145
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• 2016

Toxoplasmosis is a serious disease caused by Toxoplasma gondii, one of the most widespread parasites in the world. Lipid metabolism is important in the intracellular stage of T. gondii. Stearoyl-CoA desaturase (SCD), a key enzyme for the synthesis of unsaturated fatty acid is predicted to exist in T. gondii. Sterculic acid has been shown to specifically inhibit SCD activity. Here, we examined whether sterculic acid and its methyl ester analogues exhibit anti-T. gondii effects in vitro. T. gondii-infected Vero cells were disintegrated at 36 hr because of the propagation and egress of intracellular tachyzoites. All test compounds inhibited tachyzoite propagation and egress, reducing the number of ruptured Vero cells by the parasites. Sterculic acid and the methyl esters also inhibited replication of intracellular tachyzoites in HFF cells. Among the test compounds, sterculic acid showed the most potent activity against T. gondii, with an $EC_{50}$ value of $36.2{\mu}M$, compared with $EC_{50}$ values of $248-428{\mu}M$ for the methyl esters. Our study demonstrated that sterculic acid and its analogues are effective in inhibition of T. gondii growth in vitro, suggesting that these compounds or analogues targeting SCD could be effective agents for the treatment of toxoplasmosis.

• Journal of Genetic Medicine
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• 제10권1호
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• pp.20-26
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• 2013

Mitochondrion is an intracellular organelle with its own genome. Its function in cellular metabolism is indispensable that mitochondrial dysfunction gives rise to multisystemic failure. The manifestation is most prominent with tissues of high energy demand such as muscle and nerve. Mitochondrial myopathies occur not only by mutations in mitochondrial genome, but also by defects in nuclear genes or secondarily by toxic insult on mitochondrial replication. Currently curative treatment modality does not exist and symptomatic treatment remains mainstay. Administration of L-arginine holds great promise according to the recent reports. Advances in mitochondrial RNA import might enable a new therapeutic strategy.

• Molecules and Cells
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• 제28권4호
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• pp.403-406
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• 2009

Rev is an essential regulatory protein for HIV-1 replication. Rev (11-20) is known as the significant region regarding the function of a nuclear entry inhibitory signal (NIS) of Rev. In this study, anticandidal effects and mechanism of action of Rev (11-20) were investigated. The result exhibited that Rev (11-20) contained candidacidal activities. To understand target site(s) of Rev (11-20), the intracellular localization of the peptide was investigated. The result showed that Rev (11-20) rapidly accumulated in the fungal cell surface. The cell wall regeneration test also indicated that Rev (11-20) exerted its anticandidal activity to fungal plasma membrane rather than cell wall. The fluorescent study using 1,6-diphenyl-1,3,5-hexatriene (DPH) further confirmed the membrane-disruption mechanism(s) of Rev (11-20). The present study suggests that Rev (11-20) possesses significant potential regarding therapeutic agents for treating fungal diseases caused by Candida species in humans.

• 대한약학회:학술대회논문집
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• 대한약학회 2003년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.2-2
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• pp.180.1-180.1
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• 2003

Eukaryotic DNA topoisomerase I (top I) is an essential enzyme that act to relax supercoiled DNA during the transcription, replication and mitosis. Intracellular levels of top I are elevated in a number of human solid tumors, relative to the respective normal tissues, suggesting that controlling the topI level is important to treat cancer. Top I poisons show their antitumor activities by stabilizing the cleavable ternary complex consisting of top I enzyme, DNA, and drug. Thus, top I is a promising target for the development of new cancer chemotherapeutics against a number of solid tumors. (omitted)

• Parasites, Hosts and Diseases
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• 제54권1호
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• pp.31-38
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• 2016

Specific gene expressions of host cells by spontaneous STAT6 phosphorylation are major strategy for the survival of intracellular Toxoplasma gondii against parasiticidal events through STAT1 phosphorylation by infection provoked $IFN-{\gamma}$. We determined the effects of small molecules of tyrosine kinase inhibitors (TKIs) on the growth of T. gondii and on the relationship with STAT1 and STAT6 phosphorylation in ARPE-19 cells. We counted the number of T. gondii RH tachyzoites per parasitophorous vacuolar membrane (PVM) after treatment with TKIs at 12-hr intervals for 72 hr. The change of STAT6 phosphorylation was assessed via western blot and immunofluorescence assay. Among the tested TKIs, Afatinib (pan ErbB/EGFR inhibitor, $5{\mu}M$) inhibited 98.0% of the growth of T. gondii, which was comparable to pyrimethamine ($5{\mu}M$) at 96.9% and followed by Erlotinib (ErbB1/EGFR inhibitor, $20{\mu}M$) at 33.8% and Sunitinib (PDGFR or c-Kit inhibitor, $10{\mu}M$) at 21.3%. In the early stage of the infection (2, 4, and 8 hr after T. gondii challenge), Afatinib inhibited the phosphorylation of STAT6 in western blot and immunofluorescence assay. Both JAK1 and JAK3, the upper hierarchical kinases of cytokine signaling, were strongly phosphorylated at 2 hr and then disappeared entirely after 4 hr. Some TKIs, especially the EGFR inhibitors, might play an important role in the inhibition of intracellular replication of T. gondii through the inhibition of the direct phosphorylation of STAT6 by T. gondii.

• Journal of Veterinary Science
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• 제22권2호
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• pp.18.1-18.12
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• 2021

Background: We previously elucidated the protective mechanism of Korean red ginseng oil (RGO) against Brucella abortus infection, and our phytochemical analysis revealed that palmitic acid (PA) was an abundant component of RGO. Consequently, we investigated the contribution of PA against B. abortus. Objectives: We aimed to investigate the efficacy of PA against B. abortus infection using a murine cell line and a murine model. Methods: Cell viability, bactericidal, internalization, and intracellular replication, western blot, nitric oxide (NO), and superoxide (O₂^-) analyses and flow cytometry were performed to determine the effects of PA on the progression of B. abortus infection in macrophages. Flow cytometry for cytokine analysis of serum samples and bacterial counts from the spleens were performed to determine the effect of PA in a mouse model. Results: PA did not affect the growth of B. abortus. PA treatment in macrophages did not change B. abortus uptake but it did attenuate the intracellular survivability of B. abortus. Incubation of cells with PA resulted in a modest increase in sirtuin 1 (SIRT1) expression. Compared to control cells, reduced nitrite accumulation, augmented O₂^-, and enhanced pro-inflammatory cytokine production were observed in PA-treated B. abortus-infected cells. Mice orally treated with PA displayed a decreased serum interleukin-10 level and enhanced bacterial resistance. Conclusions: Our results suggest that PA participates in the control of B. abortus within murine macrophages, and the in vivo study results confirm its efficacy against the infection. However, further investigations are encouraged to completely characterize the mechanisms involved in the inhibition of B. abortus infection by fatty acids.

• 미생물학회지
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• 제31권1호
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• pp.72-78
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• 1993

Human cytomegalovirus (HCMV) 의 immediate early(IE) 유전자의 promoter/enhancer 부위에 cAMP response element가 있다는 것으부터 caMP 가 HCMV 의 증식에 관여할 것이라고 생각할 수 있다. 이러한 가능성을 알아보기 위해 8-bromoadenosine 3', 5'-cyclic monophosphate (BrA) 와 papaverine 같은 세포내 cAMP 농도를 변화시키는 약제를 사용하여 HCMV 의 증식, DNA 합성 및 IE 유전자 발현에 대한 영향을 알아보았다. HCMV 증식과 DNA 합성은 papaverine 에 의해 억제된 반면, BrA 는 HCMV 의 증식에는 큰 영향을 주지 않았고 DNA 합성은 오히려 촉진시키는 것을 알 수 있었다. HCMV IE promoter 에 의해 작동되는 CAT 유전자를 함유한 plasmid pCMVIE/CAT 을 세포내로 transfection 시켰을 때, papaverine 을 처리한 세포에서는 CAT 효소 활성도가 감소한 반면 BrA 를 처리한 세포에서는 증가하였다. HCMV 에 감수성이 없는 HeLa 세포에서는 CAT 활성도가 감소성 세포인 HEL 세포에서보다 높게 나타난 반면, Vero 세포에서는 낮게 나타났다. 이들 비감수성 세포인 HEL 세포에서 보다 높게 나타난 반면 Vero 세포에서는 낮게 나타났다. 이 들 비감수성 세포에서의 CAT 활성도는 BrA 를 처리하여 주었을 때 모두 증가하였다. 이상과 같은 결과로부터 cAMP 는 HCMV 증식과 IE 유전자 발현에 어느 정도 관여한다는 것을 알 수 있다.

• Molecules and Cells
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• 제39권11호
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• pp.777-782
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• 2016

The innate immune system has evolved to detect and destroy invading pathogens before they can establish systemic infection. To successfully eradicate pathogens, including viruses, host innate immunity is activated through diverse pattern recognition receptors (PRRs) which detect conserved viral signatures and trigger the production of type I interferon (IFN) and pro-inflammatory cytokines to mediate viral clearance. Viral persistence requires that viruses co-opt cellular pathways and activities for their benefit. In particular, due to the potent antiviral activities of IFN and cytokines, viruses have developed various strategies to meticulously modulate intracellular innate immune sensing mechanisms to facilitate efficient viral replication and persistence. In this review, we highlight recent advances in the study of viral immune evasion strategies with a specific focus on how Kaposi's sarcoma-associated herpesvirus (KSHV) effectively targets host PRR signaling pathways.