• 한국환경보건학회지
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• 제35권5호
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• pp.343-354
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• 2009

Since Barker found associations between low birth weight and several chronic diseases later in life, the hypothesis of fetal origins of adult disease (aka, Barker Hypothesis) and epigenetics have been emerging as a new paradigm for geneenvironment interaction of chronic disease. Epigenetics is the study of heritable changes in gene silencing that occur without any change in DNA sequence. Gene expression can be regulated by several epigenetic mechanisms, including DNA methylation and histone modifications, which may be associated with chronic conditions, such as cancers, cardiovascular disease, and type-2 diabetes. One carbon metabolism which involves the transfer of a methyl group catalyzed by DNA methyltransferase is an important mechanism by which DNA methylation occurs in promoter regions and/or repetitive elements of the genome. Environmental factors may induce epigenetic modification through production of reactive oxygen species, alteration of methyltransferase activity, and/or interference with methyl donors. In this review, we introduce recent studies of epigenetic modification and environmental factors, such as heavy metals, environmental hormones, air pollution, diet and psychosocial stress. We also discuss epigenetic perspectives of early life environmental exposure and late life disease occurrence.

• BMB Reports
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• 제49권3호
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• pp.135-136
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• 2016

Small interfering RNAs (siRNAs) have been developed to intentionally repress a specific gene expression by directing RNA-induced silencing complex (RISC), mimicking the endogenous gene silencer, microRNAs (miRNAs). Although siRNA is designed to be perfectly complementary to an intended target mRNA, it also suppresses hundreds of off-targets by the way that miRNAs recognize targets. Until now, there is no efficient way to avoid such off-target repression, although the mode of miRNA-like interaction has been proposed. Rationally based on the model called "transitional nucleation" which pre-requires base-pairs from position 2 to the pivot (position 6) with targets, we developed a simple chemical modification which completely eliminates miRNA-like off-target repression (0%), achieved by substituting a nucleotide in pivot with abasic spacers (dSpacer or C3 spacer), which potentially destabilize the transitional nucleation. Furthermore, by alleviating steric hindrance in the complex with Argonaute (Ago), abasic pivot substitution also preserves near-perfect on-target activity (∼80-100%). Abasic pivot substitution offers a general means of harnessing target specificity of siRNAs to experimental and clinical applications where misleading and deleterious phenotypes from off-target repression must be considered.

• BMB Reports
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• 제51권5호
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• pp.249-254
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• 2018

Natural pterocarpan Medicarpin (Med) has been shown to have various beneficial biological roles, including inhibition of osteoclastogenesis, stimulation of bone regeneration and induction of apoptosis. However, the effect of the Med on lipolysis in adipocytes has not been reported. Here, we show the effect of Med on lipolysis in different mouse adipocytes and elucidate the underlying mechanism. We observed that Med treatment promoted release of glycerol in the media. Differentiated mouse brown adipose tissue cells were treated with Med. RNA-Seq analysis was performed to elucidate the effect of med and subsequently was confirmed by qRT-PCR and western blotting analyses. Med treatment increased both protein and gene expression levels of hormone-sensitive lipase (Hsl) and adipose triglyceride lipase (Atgl), which are two critical enzymes necessary for lipolysis. Mechanistic study showed that Med activates Protein Kinase A (PKA) and phosphorylates Hsl at PKA target position at $Serine^{660}$. Silencing of PKA gene by short interfering RNA attenuated the Med-induced increase in glycerol release and Hsl phosphorylation. The results unveil that Med boosts lipolysis via a PKA-dependent pathway in adipocytes and may provide a possible avenue of further research of Med mediated reduction of body fat.

• Parasites, Hosts and Diseases
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• 제46권1호
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• pp.1-15
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• 2008

Introduction of double-stranded RNA (dsRNA) into some cells or organisms results in degradation of its homologous mRNA, a process called RNA interference (RNAi). The dsRNAs are processed into short interfering RNAs (siRNAs) that subsequently bind to the RNA-induced silencing complex (RISC), causing degradation of target mRNAs. Because of this sequence-specific ability to silence target genes, RNAi has been extensively used to study gene functions and has the potential to control disease pathogens or vectors. With this promise of RNAi to control pathogens and vectors, this paper reviews the current status of RNAi in protozoans, animal parasitic helminths and disease-transmitting vectors, such as insects. Many pathogens and vectors cause severe parasitic diseases in tropical regions and it is difficult to control once the host has been invaded. Intracellularly, RNAi can be highly effective in impeding parasitic development and proliferation within the host. To fully realize its potential as a means to control tropical diseases, appropriate delivery methods for RNAi should be developed, and possible off-target effects should be minimized for specific gene suppression. RNAi can also be utilized to reduce vector competence to interfere with disease transmission, as genes critical for pathogenesis of tropical diseases are knockdowned via RNAi.

• Molecules and Cells
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• 제21권3호
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• pp.401-410
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• 2006

The plastid transformation approach offers a number of unique advantages, including high-level transgene expression, multi-gene engineering, transgene containment, and a lack of gene silencing and position effects. The extension of plastid transformation technology to monocotyledonous cereal crops, including rice, bears great promise for the improvement of agronomic traits, and the efficient production of pharmaceutical or nutritional enhancement. Here, we report a promising step towards stable plastid transformation in rice. We produced fertile transplastomic rice plants and demonstrated transmission of the plastidexpressed green fluorescent protein (GFP) and aminoglycoside 3′-adenylyltransferase genes to the progeny of these plants. Transgenic chloroplasts were determined to have stably expressed the GFP, which was confirmed by both confocal microscopy and Western blot analyses. Although the produced rice plastid transformants were found to be heteroplastomic, and the transformation efficiency requires further improvement, this study has established a variety of parameters for the use of plastid transformation technology in cereal crops.

• Genomics & Informatics
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• 제9권1호
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• pp.39-43
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• 2011

MicroRNAs (miRNAs) are recently discovered small RNA molecules usually resulting in translational repression and gene silencing. Despite the fact that specific cloning of small RNA's is a method in practice, computational identification of miRNA's has been a major focus recent days, since is a rapid process following AB initio and sequence alignment methods. Here we developed new software called MiRPI that aims to identify the highly conserved miRNAs without any mismatches from given fasta formatted gene sequences by using non-repeated miRNA dataset of the user's interest. The new window embedded with the software is used to identify the targets for inputted mature miRNAs in the mRNA sequences. Also MiRPI is designed to measure the precursor miRNA statistics, majorly focusing the Adjusted Minimum Folding free Energy (AMFE) and Minimum Folding free Energy Index (MFEI), the most important parameters in miRNA confirmation. MiRPI is developed by PERL (Practical Extraction and Report Language) and Tk (Tool kit widgets) scripting languages. It is user friendly, portable offline software that works in all windows OS, sized to 3 MB.

• KSBB Journal
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• 제26권2호
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• pp.131-138
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• 2011

Some computational approaches are needed for clarifying RNAi sequences, because it takes much time and endeavor that almost of RNAi sequences are verified by experimental data. Incorrectness of RNAi mechanism and other unaware factors in organism system are frequently faced with questions regarding potential use of RNAi as therapeutic applications. Our massive parallelized pair alignment scoring between dsRNA in Genebank and expressed sequence tags (ESTs) in Caenorhabditis elegans Genome Sequencing Projects revealed that this provides a useful tool for the prediction of RNAi induced cosuppression details for practical use. This pair alignment scoring method using high performance computing exhibited some possibility that numerous unwanted gene silencing and cosuppression exist even at high matching scores each other. The classifying the relative higher matching score of them based on GO (Gene Ontology) system could present mapping dsRNA of C. elegans and functional roles in an applied system. Our prediction also exhibited that more than 78% of the predicted co-suppressible genes are located in the ribosomal spot of C. elegans.

• The Korean Journal of Physiology and Pharmacology
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• 제20권5호
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• pp.487-498
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• 2016

Leptin, an adipokine predominantly produced from adipose tissue, is well known to induce tumor growth. However, underlying molecular mechanisms are not established yet. While p53 has long been well recognized as a potent tumor suppressor gene, accumulating evidence has also indicated its potential role in growth and survival of cancer cells depending on experimental environments. In the present study, we examined if p53 signaling is implicated in leptin-induced growth of cancer cells. Herein, we demonstrated that leptin treatment significantly increased p53 protein expression in both hepatic (HepG2) and breast (MCF-7) cancer cells without significant effect on mRNA expression. Enhanced p53 expression by leptin was mediated via modulation of ubiquitination, in particular ubiquitin specific protease 2 (USP2)-dependent manner. Furthermore, gene silencing of p53 by small interfering RNA (siRNA) suppressed leptin-induced growth of hepatic and breast cancer cells, indicating the role of p53 signaling in tumor growth by leptin. In addition, we also showed that knockdown of p53 restored suppression of caspase-3 activity by leptin through modulating Bax expression and prevented leptin-induced cell cycle progression, implying the involvement of p53 signaling in the regulation of both apoptosis and cell cycle progression in cancer cells treated with leptin. Taken together, the results in the present study demonstrated the potential role of p53 signaling in leptin-induced tumor growth.

• Molecules and Cells
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• 제45권9호
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• pp.622-630
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• 2022

Colorectal cancer (CRC) has a high mortality rate among cancers worldwide. To reduce this mortality rate, chemotherapy (5-fluorouracil, oxaliplatin, and irinotecan) or targeted therapy (bevacizumab, cetuximab, and panitumumab) has been used to treat CRC. However, due to various side effects and poor responses to CRC treatment, novel therapeutic targets for drug development are needed. In this study, we identified the overexpression of EHMT1 in CRC using RNA sequencing (RNA-seq) data derived from TCGA, and we observed that knocking down EHMT1 expression suppressed cell growth by inducing cell apoptosis in CRC cell lines. In Gene Ontology (GO) term analysis using RNA-seq data, apoptosis-related terms were enriched after EHMT1 knockdown. Moreover, we identified the CHOP gene as a direct target of EHMT1 using a ChIP (chromatin immunoprecipitation) assay with an anti-histone 3 lysine 9 dimethylation (H3K9me2) antibody. Finally, after cotransfection with siEHMT1 and siCHOP, we again confirmed that CHOP-mediated cell apoptosis was induced by EHMT1 knockdown. Our findings reveal that EHMT1 plays a key role in regulating CRC cell apoptosis, suggesting that EHMT1 may be a therapeutic target for the development of cancer inhibitors.

• Asian Pacific Journal of Cancer Prevention
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• 제17권5호
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• pp.2499-2506
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• 2016

Background: Gastric cancer (GC) is the second leading cause of cancer-related death worldwide. Several environmental, genetic and epigenetic factors have been suggested to have a role in GC development. Epigenetic mechanisms like histone changes and promoter hyper-methylation are now being increasingly studied. Associations between methylation of many gene promoters with the risk of gastric cancer have been investigated worldwide. Such aberrant methylation may result in silencing of specific genes related to cell cycling, cell adhesion, apoptosis and DNA repair. Thus this molecular mechanism might have a key role in proliferation and migration of cancerous cells. Materials and Methods: In this review article we included studies conducted on DNA methylation and gastric cancer in Iranian populations. Using Science direct, Pubmed/PMC, Springer, Wiley online library and SciELO databases, all published data until 31 January 2016 were gathered. We also searched Science direct data base for similar investigations around the world to make a comparison between Iran and other countries. Results: By searching these databases, we found that the association between methylation of seven gene promoters and gastric cancer had been studied in Iran until 31 January 2016. These genes were p16, hLMH1, E-cadherin, CTLA4, $THR{\beta}$, mir9 and APC. Searching in science direct database also showed that 92 articles had been published around the world till January 2016. Our investigation revealed that despite the importance of GC and its high prevalence in Iran, the methylation status of only a few gene promoters has been studied so far. More studies with higher sample numbers are needed to reveal the relation of methylation status of gene promoters to gastric cancer in Iran. Conclusions: Further studies will be helpful in identifying associations of DNA methylation in candidate genes with gastric cancer risk in Iranian populations.