• Journal of Life Science
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• v.23 no.7
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• pp.863-868
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• 2013

The XylP gene, which encodes endoxylanase in Bacillus sp. HY-20, was subcloned, and two expression plasmids, pG-xylP and pGMF-xylP were constructed. These plasmids, which contain different signal sequences, XylP s.s and $MF{\alpha}_{opt}$ s.s, respectively, for the secretory expression of endoxylanase, were transformed into Saccharomyces cerevisiae SEY2102 and FY833, respectively. The recombinant endoxylanases were successfully expressed, with a total activity range of 23.7-70.1 unit/ml according to the expression system and host strain. The endoxylanase activity in SEY2102/pGMF-xylP reached a maximum of 88.1 unit/ml in baffled flask culture. Most of the recombinant endoxylanase was efficiently secreted in the extracellular fraction, and the $MF{\alpha}_{opt}$ s.s was more efficient for secreting endoxylanase in yeast than the XylP s.s. Therefore, the expression system developed in this study produces large extracellular amounts of endoxylanase using S. cerevisiae as the host strain, and it could be used in bioethanol production and industrial applications.

• International Journal of Oral Biology
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• v.34 no.1
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• pp.21-28
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• 2009

Mutations in DLX3 are associated with both autosomal dominant hypoplastic hypomaturation amelogenesis imperfecta (ADHHAI) and tricho-dento-osseous (TDO) syndrome. ADHHAI is caused by a c.561_562delCT (2bp-del DLX3) mutation whereas TDO syndrome is associated with a c.571_574delGGGG (4bp-del DLX3) mutation. However, although the causal relationships between DLX3 and an enamel phenotype have been established, the pathophysiological role of DLX3 mutations in enamel development has not yet been clarified. In our current study, we prepared expression vectors for wild type and deletion mutant DLX3 products (4bp-del DLX3, 2bp-del DLX3) and examined the effects of their overexpression on the expression of the enamel matrix proteins and proteases. Wild type DLX3 enhanced the expression of matrix metalloprotease 20 (MMP20) mRNA and protein in murine ameloblast-like cells. However, neither a 4bp-del nor 2bp-del DLX3 increased MMP20 expression. Wild type DLX3, but not the above DLX3 mutants, also increased the activity of reporters containing 1.5 kb or 0.5 kb of the MMP20 promoter. An examination of protein stability showed that the half-life of wild type DLX3 protein was less than 12 h whilst that of both deletion mutants was longer than 24 h. Endogenous Dlx3 was also found to be continuously expressed during ameloblast differentiation. Since inactivating mutations in the gene encoding MMP20 are associated with amelogenesis imperfecta, the inability of 4bp-del or 2bp-del DLX3 to induce MMP20 expression suggests a possible involvement of such mutations in the enamel phenotype associated with TDO syndrome or ADHHAI.

• Korean Journal of Microbiology
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• v.50 no.4
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• pp.308-312
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• 2014

In this study, we conducted a next generation sequencing based microbial community analysis to investigate gut microbiota of the two commercially most available swine breeds, Yorkshire and Landrace. Bacterial 16S rRNA gene was amplified from fecal DNA using universal primer sets designed for V4 regions. Our comparison analysis of the gut microbiota of the two breeds suggested that their gut microbiota changed depending on the growth stages, while the difference between the two breeds was insignificant. However, there was a limited number of genera, the abundance of which was found to be different between the breeds. Those included the genus Xylanibacter in the Yorkshire samples, which was previously reported as a fiber digesting bacteria, likely increasing energy harvesting capacity of swine. In addition, others included opportunistic pathogens mostly found in the Yorkshire samples while the Landrace samples had significantly more prevalent Clostridium_IV species that were known to play a key role in systemic immunity of hosts. While microbial community shifts was found to be associated with growth stages, the difference between the two breeds seemed to be insignificant. However, there were several bacterial genera showing differential abundance, which may affect growth of hosts.

• Journal of Microbiology and Biotechnology
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• v.25 no.8
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• pp.1339-1348
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• 2015

Until now, considerable effort has been made to engineer novel nitrogen-fixing organisms through the transfer of nif genes from various diazotrophs to non-nitrogen fixers; however, regulatory coupling of the heterologous nif genes with the regulatory system of the new host is still not well understood. In this work, a 49 kb nitrogen fixation island from P. stutzeri A1501 was transferred into E. coli using a novel and efficient transformation strategy, and a series of recombinant nitrogen-fixing E. coli strains were obtained. We found that the nitrogenase activity of the recombinant E. coli strain EN-01, similar to the parent strain P. stutzeri A1501, was dependent on external ammonia concentration, oxygen tension, and temperature. We further found that there existed a regulatory coupling between the E. coli general nitrogen regulatory system and the heterologous P. stutzeri nif island in the recombinant E. coli strain. We also provided evidence that the E. coli general nitrogen regulator GlnG protein was involved in the activation of the nif-specific regulator NifA via a direct interaction with the NifA promoter. To the best of our knowledge, this work plays a groundbreaking role in increasing understanding of the regulatory coupling of the heterologous nitrogen fixation system with the regulatory system of the recipient host. Furthermore, it will shed light on the structure and functional integrity of the nif island and will be useful for the construction of novel and more robust nitrogen-fixing organisms through biosynthetic engineering.

• Korean Journal of Environmental Biology
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• v.27 no.1
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• pp.58-65
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• 2009

The chemopreventive effects of naringenin derived from citrus on tumor migration and the possible mechanisms involved in this protection were investigated in HT-1080 tumor cells. In this study, we found that naringenin reduced phorbol 12-myristate 13-acetate (PMA)-enhanced matrix metalloproteinases (MMP)-9 activation in a dose-dependant manner and further inhibited HT-1080 cell migration. In addition, naringenin suppressed PMA-enhanced expression of MMP-9 protein, mRNA and transcription activity levels through suppression of nuclear factor $\kappa$B (NF-$\kappa$B) activation and activator protein-1 (AP-1) translocation without changing tissue inhibitor of metalloproteinase (TIMP)-1 level. Therefore, our results suggested that the inhibitory effects of naringenin on MMP-9 activation, relation of tumor migration in vitro possibly involve mechanisms related to its ability to suppress PMA-enhanced MMP-9 gene and protein expression through NF-$\kappa$B activation and AP-1 translocation. Overall, naringenin may be a valuable anti-invasive drug candidate for cancer therapy.

• Reproductive and Developmental Biology
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• v.30 no.3
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• pp.181-187
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• 2006

In recent years the number of patients waiting for organ transplantation has greatly outpaced the supply of human organs available, which leads to a renewed interest in pig-to-human xenotransplantation as an alternative. However, one of the biggest barriers in the xenotransplantation is presence of porcine endogenous retroviruses(PERV) that can infect human cells. In this study, to present a possible solution for this problem we tried to inhibit expression of PERVs using shRNAs(short hairpin RNA) at the level of RNA synthesis and virus release. The shRNA targeting the sequence of PERV A, B type was cloned into pSIREN-RetroQ vector under the control of polymerase-III U6-RNA gene promoter. Quantitative real-time PCR was performed to detect my alterations in mRNA production of PERV A, B targeted by the shRNA in each done. Depending on the target sequence of the shRNA, the transcription of PERV was decreased to as much as 4% and the number of progeny viruses was reduced to less than 1/200,000. Transgenic pigs producing such shRNAs may result in a highly reduced PERV expression in cells and organs, which is a prerequisite for safe xenotransplantations.

• Experimental and Molecular Medicine
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• v.50 no.12
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• pp.1.1-1.14
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• 2018

DNA methylation is a regulatory mechanism in epigenetics that is frequently altered during human carcinogenesis. To detect critical methylation events associated with gastric cancer (GC), we compared three DNA methylomes from gastric mucosa (GM), intestinal metaplasia (IM), and gastric tumor (GT) cells that were microscopically dissected from an intestinal-type early gastric cancer (EGC) using methylated DNA binding domain sequencing (MBD-seq) and reduced representation bisulfite sequencing (RRBS) analysis. In this study, we focused on differentially methylated promoters (DMPs) that could be directly associated with gene expression. We detected 2,761 and 677 DMPs between the GT and GM by MBD-seq and RRBS, respectively, and for a total of 3,035 DMPs. Then, 514 (17%) of all DMPs were detected in the IM genome, which is a precancer of GC, supporting that some DMPs might represent an early event in gastric carcinogenesis. A pathway analysis of all DMPs demonstrated that 59 G protein-coupled receptor (GPCR) genes linked to the hypermethylated DMPs were significantly enriched in a neuroactive ligand-receptor interaction pathway. Furthermore, among the 59 GPCRs, six GI hormone receptor genes (NPY1R, PPYR1, PTGDR, PTGER2, PTGER3, and SSTR2) that play an inhibitory role in the secretion of gastrin or gastric acid were selected and validated as potential biomarkers for the diagnosis or prognosis of GC patients in two cohorts. These data suggest that the loss of function of gastrointestinal (GI) hormone receptors by promoter methylation may lead to gastric carcinogenesis because gastrin and gastric acid have been known to play a role in cell differentiation and carcinogenesis in the GI tract.

• Journal of Life Science
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• v.29 no.9
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• pp.1047-1054
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• 2019

Transposable elements (TEs) occupy approximately 45% of the human genome and can enter functional genes randomly. During evolutionary radiation, multiple copies of TEs are produced by duplication events. Those elements contribute to biodiversity and phylogenomics. Most of them are controlled by epigenetic regulation, such as methylation or acetylation. Every species contains their own specific mobile elements, and they are divided into DNA transposons and retrotransposons. Retrotransposons can be divided by the presence of a long terminal repeat (LTR). They show various biological functions, such as promoter, enhancer, exonization, rearrangement, and alternative splicing. Also, they are strongly implicated to genomic instability, causing various diseases. Therefore, they could be used as biomarkers for the diagnosis and prognosis of diseases such as cancers. Recently, it was found that TEs could produce miRNAs, which play roles in gene inhibition through mRNA cleavage or translational repression, binding seed regions of target genes. Studies of TE-derived miRNAs offer a potential for the expression of functional genes. Comparative analyses of different types of miRNAs in various species and tissues could be of interest in the fields of evolution and phylogeny. Those events allow us to understand the importance of TEs in relation to biological roles and various diseases.

• BMB Reports
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• v.56 no.10
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• pp.563-568
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• 2023

DNA methylation regulates gene expression and contributes to tumorigenesis in the early stages of cancer. In colorectal cancer (CRC), CpG island methylator phenotype (CIMP) is recognized as a distinct subset that is associated with specific molecular and clinical features. In this study, we investigated the genome-wide DNA methylation patterns among patients with CRC. The methylation data of 1 unmatched normal, 142 adjacent normal, and 294 tumor samples were analyzed. We identified 40,003 differentially methylated positions with 6,933 (79.8%) hypermethylated and 16,145 (51.6%) hypomethylated probes in the genic region. Hypermethylated probes were predominantly found in promoter-like regions, CpG islands, and N shore sites; hypomethylated probes were enriched in open-sea regions. CRC tumors were categorized into three CIMP subgroups, with 90 (30.6%) in the CIMP-high (CIMP-H), 115 (39.1%) in the CIMP-low (CIMP-L), and 89 (30.3%) in the non-CIMP group. The CIMP-H group was associated with microsatellite instability-high tumors, hypermethylation of MLH1, older age, and right-sided tumors. Our results showed that genome-wide methylation analyses classified patients with CRC into three subgroups according to CIMP levels, with clinical and molecular features consistent with previous data.

• Tuberculosis and Respiratory Diseases
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• v.62 no.5
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• pp.406-416
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• 2007

Background: Single nucleotide polymorphisms (SNPs), which consist of a substitution of a single nucleotide pair, are the most abundant form of genetic variations occurring with a frequency of approximately 1 per 1000 base pairs. SNPs by themselves do not cause disease but can predispose humans to disease, modify the extent or severity of the disease or influence the drug response and treatment efficacy. Single nucleotide polymorphisms (SNPs), particularly those within the regulatory regions of the genes often influence the expression levels and can modify the disease. Studies examining the associations between SNP and the disease outcome have provided valuable insight into the disease etiology and potential therapeutic intervention. Traditionally, the genotyping of SNPs has been carried out using polymerase chain reaction-restriction fragment length polymorphism(PCR-RFLP), which is a low throughput technique not amenable for use in large-scale SNP studies. Recently, TaqMan real-time PCR chemistry was adapted for use in allelic discrimination assays. This study validated the accuracy and utility of real-time PCR technology for SNPs genotyping Methods: The SNPs in promoter sequence (-37 and -524) of lung cancer suppressor gene, RRM1 (ribonucleotide reductase M1 subunit) with the genomic DNA samples of 89 subjects were genotyped using both real-time PCR and PCR-RFLP. Results: The discordance rates were 2.2% (2 mismatches) in -37 and 16.3% (15 mismatches) in -524. Auto-direct sequencing of all the mismatched samples(17 cases) were in accord with the genotypes read by real-time PCR. In addition, 138 genomic DNAs were genotyped using real-time PCR in a duplicate manner (two separated assays). Ninety-eight percent of the samples showed concordance between the two assays. Conclusion: Real-time PCR allelic discrimination assays are amenable to high-throughput genotyping and overcome many of the problematic features associated with PCR-RFLP.