• BMB Reports
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• v.52 no.5
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• pp.330-335
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• 2019

Hepatitis B virus (HBV) encoding the HBV x protein (HBx) is a known causative agent of hepatocellular carcinoma (HCC). Its pathogenic activities in HCC include interference with several signaling pathways associated with cell proliferation and apoptosis. Mutant C-terminal-truncated HBx isoforms are frequently found in human HCC and have been shown to enhance proliferation and invasiveness leading to HCC malignancy. We investigated the molecular mechanism of the reduced doxorubicin cytotoxicity by C-terminal truncated HBx. Cells transfected with C-terminal truncated HBx exhibited reduced cytotoxicity to doxorubicin compared to those transfected with full-length HBx. The doxorubicin resistance of cells expressing C-terminal truncated HBx correlated with upregulation of the ATP binding cassette subfamily B member 1(ABCB1) transporter, resulting in the enhanced efflux of doxorubicin. Inhibiting the activity of ABCB1 and silencing ABCB1 expression by small interfering ribonucleic acid (siRNA) increased the cytotoxicity of doxorubicin. These results indicate that elevated ABCB1 expression induced by C-terminal truncation of HBx was responsible for doxorubicin resistance in HCC. Hence, co-treatment with an ABCB1 inhibitor and an anticancer agent may be effective for the treatment of patients with liver cancer containing the C-terminal truncated HBx.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.81.2-82
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• 2003

Plants have evolved along with pathogens, and they have developed sophisticated defense systems against specific microorganisms to survive. G-protons are considered one of the upstream signaling components working as a key for the defense signal transduction pathway. For activation and inactivation of G-protein, GTP-biding proteins are involved. GTP -binding proteins are found in all organisms. Small GTP-binding proteins, having masses of 21 to 30kD, belong to a superfamily, often named the Ras supefamily because the founding members are encoded by human Ras genes initially discovered as cellular homologs of the viral ras oncogene. Members of this supefamily share several common structural features, including several guanine nucleotide binding domains and an effector binding domain. However, exhibiting a remarkable diversity in both structure and function. They are important molecular switches that cycle between the GDP-bound inactive form into the GTP-bound active form through GDP/GTP replacement. In addition, most GTP-binding proteins cycle between membrane-bound and cytosolic forms. such as the RAC family are cytosolic signal transduction proteins that often are involved in processing of extracellular stimuli. Plant RAC proteins are implicated in regulation of plant cell architecture secondary wall formation, meristem signaling, and defense against pathogens. But their molecular mechanisms and functions are not well known. We isolated a RacB homolog from rice to study its role of defense against pathogens. We introduced the constitutively active and the dominant negative forms of the GTP-hinging protein OsRacB into the wild type rice. The dominant negative foms are using two forms (full-sequence and specific RNA interference with RacB). Employing southern, and protein analysis, we examine to different things between the wild type and the transformed plant. And analyzing biolistic bombardment of onion epidermal cell with GFP-RacB fusion protein revealed association with the nucle.

• BMB Reports
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• v.37 no.1
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• pp.107-113
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• 2004

Since the completion of the genome project of the nematode C. elegans in 1998, functional genomic approaches have been applied to elucidate the gene and protein networks in this model organism. The recent completion of the whole genome of C. briggsae, a close sister species of C. elegans, now makes it possible to employ the comparative genomic approaches for identifying regulatory mechanisms that are conserved in these species and to make more precise annotation of the predicted genes. RNA interference (RNAi) screenings in C. elegans have been performed to screen the whole genome for the genes whose mutations give rise to specific phenotypes of interest. RNAi screens can also be used to identify genes that act genetically together with a gene of interest. Microarray experiments have been very useful in identifying genes that exhibit co-regulated expression profiles in given genetic or environmental conditions. Proteomic approaches also can be applied to the nematode, just as in other species whose genomes are known. With all these functional genomic tools, genetics will still remain an important tool for gene function studies in the post genome era. New breakthroughs in C. elegans biology, such as establishing a feasible gene knockout method, immortalized cell lines, or identifying viruses that can be used as vectors for introducing exogenous gene constructs into the worms, will augment the usage of this small organism for genome-wide biology.

• Asian-Australasian Journal of Animal Sciences
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• v.28 no.6
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• pp.876-887
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• 2015

Dicer, an ribonuclease type III type endonuclease, is the key enzyme involved in biogenesis of microRNAs (miRNAs) and small interfering RNAs (siRNAs), and thus plays a critical role in RNA interference through post transcriptional regulation of gene expression. This enzyme has not been well studied in the Indian water buffalo, an important species known for disease resistance and high milk production. In this study, the primary coding sequence (5,778 bp) of bubaline dicer (GenBank: AB969677.1) was determined and the bubaline Dicer1 biocomputationally characterized to determine the phylogenetic signature among higher eukaryotes. The evolutionary tree revealed that all the transcript variants of Dicer1 belonging to a specific species were within the same node and the sequences belonging to primates, rodents and lagomorphs, avians and reptiles formed independent clusters. The bubaline dicer1 is closely related to that of cattle and other ruminants and significantly divergent from dicer of lower species such as tapeworm, sea urchin and fruit fly. Evolutionary divergence analysis conducted using MEGA6 software indicated that dicer has undergone purifying selection over the time. Seventeen divergent sequences, representing each of the families/taxa were selected to study the specific regions of positive vis-$\grave{a}$-vis negative selection using different models like single likelihood ancestor counting, fixed effects likelihood, and random effects likelihood of Datamonkey server. Comparative analysis of the domain structure revealed that Dicer1 is conserved across mammalian species while variation both in terms of length of Dicer enzyme and presence or absence of domain is evident in the lower organisms.

• BMB Reports
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• v.41 no.11
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• pp.765-770
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• 2008

Undesirable hyperpigmentation that can arise from increased melanocyte activity may be alleviated by targeting active melanocytes for apoptosis. The role of Stathmin 1 as an important regulator of microtubule dynamics is well documented. The current study examined the potential of Stathmin 1-targeting strategies in eliminating active melanocytes. A vector to overexpress Stathmin 1 and vectors to express three distinct small hairpin RNAs to knockdown Stathmin 1 expression in normal melanocytes were produced and in cell cultures acted accordingly. Both overexpression and knockdown of Stathmin 1 led to a marked increase in melanocyte apoptosis, as indicated by the accumulation of apoptotic cells and increased levels of cleaved caspase-3. Both up- and down-regulation of Stathmin 1 expression inhibited the activity of differentiated melanocytes, as indicated by decreases in both melanin production and tyrosinase activity. Taken together, these results indicate that hyperactive melanocytes can be inhibited by altering Stathmin 1 expression.

• Biomolecules & Therapeutics
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• v.21 no.1
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• pp.29-34
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• 2013

The tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) is a member of the tumor necrosis factor family of cytokines. TRAIL selectively induces apoptotic cell death in various tumors and cancer cells, but it has little or no toxicity in normal cells. Agonism of TRAIL receptors has been considered to be a valuable cancer-therapeutic strategy. However, more than 85% of primary tumors are resistant to TRAIL, emphasizing the importance of investigating how to overcome TRAIL resistance. In this report, we have found that nemadipine-A, a cell-permeable L-type calcium channel inhibitor, sensitizes TRAIL-resistant cancer cells to this ligand. Combination treatments using TRAIL with nemadipine-A synergistically induced both the caspase cascade and apoptotic cell death, which were blocked by a pan caspase inhibitor (zVAD) but not by autophagy or a necrosis inhibitor. We further found that nemadipine-A, either alone or in combination with TRAIL, notably reduced the expression of survivin, an inhibitor of the apoptosis protein (IAP) family of proteins. Depletion of survivin by small RNA interference (siRNA) resulted in increased cell death and caspase activation by TRAIL treatment. These results suggest that nemadipine-A potentiates TRAIL-induced apoptosis by down-regulation of survivin expression in TRAIL resistant cells. Thus, combination of TRAIL with nemadipine-A may serve a new therapeutic scheme for the treatment of TRAIL resistant cancer cells, suggesting that a detailed study of this combination would be useful.

• Journal of Life Science
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• v.17 no.1 s.81
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• pp.110-115
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• 2007

It has been previously described that transcription factor early growth response gene product 1 (EGR-1) functions as a tumor suppressor gene. This study was conducted to demonstrate that EGR-1 induction by phytochemical apigenin and its derivative isovitexin can mediate the growth suppression of the intestinal epithelial tumor cells. Apigenin and isovitexin induced EGR-1 gene expression both in the dose and time-dependent manners. Moreover the induction was relatively late around 9-12 hr after treatment of HCT-116 cells, while several anti-inflammatory agent such as NSAIDS and catechins elicit the ECR-1 gene expression at much earlier time about 1-3 hr after treatment. In terms of signal transduction, ERK1/2 was critical for apigenin-induced EGR-1 gene expression and its promoter activation. When EGR-1 gene expression was blocked with EGR-1 small interference RNA, the cytotoxicity of apigenin in the human epithelial cells was attenuated, suggesting the involvement of EGR-1 in the anti-tumoric activity of apigenin. To link the EGR-1 induction to EGR-1-regulated gene products in colon cancer, NSAID-Activated Gene 1 (NAG-1) was demonstrated to be elevated by apigenin and isovitexin at 24-48 hr after treatment. Taken together, apigenin-activated ERK1/2 mediated EGR-1 gene induction, which was associated with suppression of the cellular viability by apigenin compound.

• Korean Journal of Breeding Science
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• v.42 no.5
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• pp.515-524
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• 2010

The amylose content of starch is a major factor in the texture of cooked cereal grains. Therefore, down-regulation of amylose synthesis is one of the alternative method to improve eating quality of rice. We developed transgenic rice plants designed to suppress granule-bound starch synthase I(GBSSI) gene using RNA interference(RNAi) technology. Transgenic plants with RNAi vector containing the 3'-UTR region of GBSSI showed a lower amylose content in rice endosperm than that of wild-type. The range of amylose content was 5.9~9.0% in the transgenic plants, whereas that of wild-type was 17.7~18.0%. Transgenic rices showed the decrease of short chain and the increase of long chain by analyzing chain length distribution of amylopectin in the endosperm. In the SEM micrographs, we found that compound starch granules in whole grains of the wild-type rice were readily split during fracturing, while the starch granules in RNAi-transgenic lines showed small voluminous, non-angular rounded bodies.