• 한국자원식물학회지
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• 제30권3호
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• pp.265-271
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• 2017

In this study, we elucidated the molecular mechanism of silymarin by which silymarin may inhibits cell proliferation in human colorectal cancer cells in order to search the new potential anti-cancer target associated with the cell growth arrest. Silymarin reduced the level of c-Myc protein but not mRNA level indicating that silymarin-mediated downregulation of c-Myc may result from the proteasomal degradation. In the confirmation of silymarin-mediated c-Myc degradation, MG132 as a proteasome inhibitor attenuated c-Myc degradation by silymarin. In addition, silymarin phosphorylated the threonine-58 (Thr58) of c-Myc and the point mutation of Thr58 to alanine blocked its degradation by silymarin, which indicates that Thr58 phosphorylation may be an important modification for silymarin-mediated c-Myc degradation. We observed that the inhibition of ERK1/2, p38 and $GSK3{\beta}$ blocked the Thr58 phosphorylation and subsequent c-Myc degradation by silymarin. Finally, the point mutation of Thr58 to alanine attenuated silymarin-mediated inhibition of the cell growth. The results suggest that silymarin induces the cell growth arrest through c-Myc proteasomal degradation via ERK1/2, p38 and $GSK3{\beta}-dependent$ Thr58 phosphorylation.

• Journal of Microbiology and Biotechnology
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• 제19권4호
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• pp.339-345
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• 2009

We evaluated the activity and abundance of the crude-oil-degrading bacterium Nocardia sp. H17-1 during bioremediation of oil-contaminated soil, using real-time PCR. The total petroleum hydrocarbon(TPH) degradation rate constants(k) of the soils treated with and without H17-1 were $0.103\;d^{-1}$ and $0.028\;d^{-1}$ respectively. The degradation rate constant was 3.6 times higher in the soil with H17-1 than in the soil without H17-1. In order to detect and quantify the Nocardia sp. H17-1 in soil samples, we quantified the genes encoding 16S ribosomal RNA(16S rRNA), alkane monooxygenase(alkB4), and catechol 2,3-dioxygenase(23CAT) with real-time PCR using SYBR green. The amounts of H17-1 16S rRNA and alkB4 detected increased rapidly up to 1,000-folds for the first 10 days, and then continued to increase only slightly or leveled off. However, the abundance of the 23CAT gene detected in H17-1-treated soil, where H17-1 had neither the 23CAT gene for the degradation of aromatic hydrocarbons nor the catechol 2,3-dioxygenase activity, did not differ significantly from that of the untreated soil($\alpha$=0.05,p>0.22). These results indicated that H17-1 is a potential candidate for the bioaugmentation of alkane-contaminated soil. Overall, we evaluated the abundance and metabolic activity of the bioremediation strain H17-1 using real-time PCR, independent of cultivation.

• 한국자원식물학회지
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• 제30권6호
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• pp.640-646
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• 2017

In this study, we elucidated anti-cancer activity and potential molecular mechanism of 70% ethanol extracts from Taxilli Ramulus (Taxillus chinensis (DC.) Danser) (TR-E70) against human colorectal cancer cells. Anti-cell proliferative effect of TR-E70 was evaluated by MTT assay. The effect of TR-E70 on the expression of cyclin D1 in the protein and mRNA level was evaluated by Western blot and RT-PCR, respectively. TR-E70 suppressed the proliferation of human colorectal cancer cell lines, HCT116 and SW480. Although TR-E70 decreased cyclin D1 expression in protein and mRNA level, decreased level of cyclin D1 protein by TR-E70 more dramatically occurred than that of cyclin D1 mRNA. Cyclin D1 downregulation by TR-E70 was attenuated in presence of MG132. In addition, TR-E70 phosphorylated threonine-286 (T286) of cyclin D1. TR-E70-mediated cyclin D1 degradation was blocked in presence of LiCl as an inhibitor $GSK3{\beta}$ but not PD98059 as an ERK1/2 inhibitor and SB203580 as a p38 inhibitor. Our results suggest that TR-E70 may downregulate cyclin D1 as one of the potential anti-cancer targets through $GSK3{\beta}$-dependent cyclin D1 degradation. From these findings, TR-E70 has potential to be a candidate for the development of chemoprevention or therapeutic agents for human colorectal cancer.

• Toxicological Research
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• 제33권3호
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• pp.211-218
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• 2017

Cytochrome P450 1B1 (CYP1B1) acts as a hydroxylase for estrogen and activates potential carcinogens. Moreover, its expression in tumor tissues is much higher than that in normal tissues. Despite this association between CYP1B1 and cancer, the detailed molecular mechanism of CYP1B1 on cancer progression in HeLa cells remains unknown. Previous reports indicated that the mRNA expression level of Herc5, an E3 ligase for ISGylation, is promoted by CYP1B1 suppression using specific small interfering RNA, and that ISGylation may be involved in ubiquitination related to ${\beta}-catenin$ degradation. With this background, we investigated the relationships among CYP1B1, Herc5, and ${\beta}-catenin$. RT-PCR and western blot analyses showed that CYP1B1 overexpression induced and CYP1B1 inhibition reduced, respectively, the expression of $Wnt/{\beta}-catenin$ signaling target genes including ${\beta}-catenin$ and cyclin D1. Moreover, HeLa cells were treated with the CYP1B1 inducer $7,12-dimethylbenz[{\alpha}]anthracene$ (DMBA) or the CYP1B1 specific inhibitor, tetramethoxystilbene (TMS) and consequently DMBA increased and TMS decreased ${\beta}-catenin$ and cyclin D1 expression, respectively. To determine the correlation between CYP1B1 expression and ISGylation, the expression of ISG15, a ubiquitin-like protein, was detected following CYP1B1 regulation, which revealed that CYP1B1 may inhibit ISGylation through suppression of ISG15 expression. In addition, the mRNA and protein expression levels of Herc5 were strongly suppressed by CYP1B1. Finally, an immunoprecipitation assay revealed a direct physical interaction between Herc5 and ${\beta}-catenin$ in HeLa cells. In conclusion, these data suggest that CYP1B1 may activate $Wnt/{\beta}-catenin$ signaling through stabilization of ${\beta}-catenin$ protein from Herc5-mediated ISGylation for proteosomal degradation.

• Journal of Microbiology and Biotechnology
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• 제27권9호
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• pp.1670-1680
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• 2017

Lignocellulose, composed mostly of cellulose, hemicellulose, and lignin generated through secondary growth of woody plant, is considered as promising resources for biofuel. In order to use lignocellulose as a biofuel, biodegradation besides high-cost chemical treatments were applied, but knowledge on the decomposition of lignocellulose occurring in a natural environment is insufficient. We analyzed the 16S rRNA gene and metagenome to understand how the lignocellulose is decomposed naturally in decayed Torreya nucifera (L) of Bija forest (Bijarim) in Gotjawal, an ecologically distinct environment. A total of 464,360 reads were obtained from 16S rRNA gene sequencing, representing diverse phyla; Proteobacteria (51%), Bacteroidetes (11%) and Actinobacteria (10%). The metagenome analysis using single molecules real-time sequencing revealed that the assembled contigs determined originated from Proteobacteria (58%) and Actinobacteria (10.3%). Carbohydrate Active enZYmes (CAZy)- and Protein families (Pfam)-based analysis showed that Proteobacteria was involved in degrading whole lignocellulose, and Actinobacteria played a role only in a part of hemicellulose degradation. Combining these results, it suggested that Proteobacteria and Actinobacteria had selective biodegradation potential for different lignocellulose substrates. Thus, it is considered that understanding of the systemic microbial degradation pathways may be a useful strategy for recycle of lignocellulosic biomass, and the microbial enzymes in Bija forest can be useful natural resources in industrial processes.

• Journal of Microbiology and Biotechnology
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• 제24권1호
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• pp.8-12
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• 2014

Biofilm formation and antibiotic resistance are important determinants for bacterial pathogenicity. Ribonucleases control RNA degradation and there is increasing evidence that they have an important role in virulence mechanisms. In this report, we show that ribonucleases affect susceptibility against ribosome-targeting antibiotics and biofilm formation in Salmonella.

• BMB Reports
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• 제53권12호
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• pp.611-621
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• 2020

Bacterial endoribonuclease toxins belong to a protein family that inhibits bacterial growth by degrading mRNA or rRNA sequences. The toxin genes are organized in pairs with its cognate antitoxins in the chromosome and thus the activities of the toxins are antagonized by antitoxin proteins or RNAs during active translation. In response to a variety of cellular stresses, the endoribonuclease toxins appear to be released from antitoxin molecules via proteolytic cleavage of antitoxin proteins or preferential degradation of antitoxin RNAs and cleave a diverse range of mRNA or rRNA sequences in a sequence-specific or codon-specific manner, resulting in various biological phenomena such as antibiotic tolerance and persister cell formation. Given that substrate specificity of each endoribonuclease toxin is determined by its structure and the composition of active site residues, we summarize the biology, structure, and substrate specificity of the updated bacterial endoribonuclease toxins.

• Biotechnology and Bioprocess Engineering:BBE
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• 제5권6호
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• pp.422-430
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• 2000

Mechanism of lignin biodegradation caused by basidiomycetes and the history of lignin biodegradation studies were briefly reviewed. The important roles of fungal extracellular ligninolytic enzymes such as lignin and manganese peroxidases (LiP and MnP) were also summarized. These enzymes were unique in their catalytic mechanisms and substrate specificities. Either LiP or MnP system is capable of oxidizing a variety of aromatic substrates via a one-electron oxidation. Extracellular fungal system for aromatic degradation is non-specific, which recently attracts many people working a bioremediation field. On the other hand, an intracellular degradation system for aromatic compounds is rather specific in the fungal cell. Structurally similar compounds were prepared and metabolized, indicating that an intracellular degradation strategy consisted of the cellular systems for substrate recognition and metabolic response. It was assumed that lignin-degrading fungi might be needed to develop multiple metabolic pathways for a variety of aromatic compounds caused by the action of non-specific ligninolytic enzymes on lignin. Our recent results on chemical stress responsible factors analyzed using mRNA differential display techniques were also mentioned.

• Journal of Microbiology and Biotechnology
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• 제13권2호
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• pp.309-312
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• 2003

A bacterial strain NB01, isolated from wastewater, was found to utilize nitrobenzene (NB) as the sole source of nitrogen, carbon, and energy. The strain was classified as a member of a high G+C Gram-positive group and identified as Mycobacterium chelonae based on an analysis of its 16S rRNA gene sequence. The strain grew on NB with a concomitant release of about 63% of the total available nitrogen as ammonia, suggesting a reductive degradation mechanism. The optimal pH and temperature for degradation were PH 7.0-8.0 and $30^{\circ}C$, respectively. The cell growth was retarded at NB concentrations above 1.8 mM. The degradation of NB followed Michaelis-Menten kinetics within the tolerance range, and the $K_m$ and maximum specific removal rate for NB were 0.33 mM and $11.04\;h^{-1}$, respectively.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 2005년도 춘계학술대회
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• pp.5-14
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• 2005

Recently, data from several groups have raised the concept of 'checkpoint' in transcription. As capping of nascent RNA transcript is tightly coupled to RNA polymerase II transcription, we seek to obtain direct evidence that transcripiton checkpoint via capping enzyme functions in this early regulatory step. One of temperature sensitive (ts) alleles of ceg1, a guanylyltransferase subunit of the Saccharomyces cerevisiaecapping enzyme, showed 6-azauracil (6AU) sensitivity at the permissive growth temperature, which is a phenotype that is correlated with a transcription elongational defect. This ts allele, ceg1-63 also has an impaired ability to induce PUR5 in response to a 6AU treatment. However, this cellular and molecular defect is not due to the preferential degradation of the transcript attributed from a lack of guanylyltransferase activity. On the contrary, the data suggests that the guanylyltransferase subunit of the capping enzyme plays a role in transcription elongation. First, in addition to the 6AU sensitivity, ceg1-63is synthetically lethal with elongation defective mutations of the largest subunit of RNA polymerase II. Secondly, it exhibited a lower GAL1 mRNA turn-over after glucoseshut off. Third, it decreased the transcription read through a tandem array of promoter proximal pause sites in an orientation dependent manner. Interestingly, this mutant also showed lower pass through a pause site located further downstream of the promoter. Taken together, these results suggest that the capping enzyme plays the role of an early transcription checkpoint possibly in the step of the reversion of repression by stimulating polymerase to escape from the promoter proximal arrest once RNA becomes appropriately capped.