• Korean Journal of Microbiology
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• v.45 no.3
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• pp.263-267
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• 2009

An RpoS factor is a transcriptional regulator which participates in numerous biological processes. In this work, we investigated the transcriptional regulation of proBA and proC composing proline biosynthetic pathway in Escherichia coli. While the proBA and proC genes were greatly induced in an exponential growth phase, they were dramatically repressed in a stationary growth phase in the wild type E. coli. Unlike the wild type E. coli, the proBA and proC genes were not repressed even in the stationary growth phase in its isogenic rpoS mutant. These results suggest that the RpoS factor acts as a transcriptional repressor of proBA and proC genes. The production of threonine, methionine, lysine, and arginine in the rpoS mutant were also increased by more than two times compared to its parental wild type, suggesting that the mutant is able to be used as an useful host strain for the amino acid overproduction.

• Applied Biological Chemistry
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• v.44 no.1
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• pp.1-6
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• 2001

To elucidate the apoptosis mechanism of Trichoplusia ni cell, fundamental studies for apoptosis induction and suppression were performed. Hygromycin B, a known inducer of apoptosis, started the inhibition of T. ni cell growth at $200\;{\mu}/ml$ concentration. Furthermore, at $400\;{\mu}/ml$ concentration, DNA fragmentation was detected on day 2 of incubation. Although both dexamethasone and sodium butyrate inhibited T. ni cell growth, DNA fragmentation was not detected by both treatments. Also, when apoptosis induced T. ni cells with $200\;{\mu}/ml$ hygromycin B were treated with caspase inhibitor (Ac-DEVD-CHO), the apoptotsis was suppressed by 36%. In addition, N-acetylcysteine, another apoptosis repressor, also inhibited the apoptosis of T. ni cells. In order to express the anti-apoptosis gene (bcl-2), T. ni cells were transiently transformed with bcl-2 and its expression was confirmed by western blot analysis. These results showed the potential of developing new insect cell lines with suppressed apoptosis.

• Animal cells and systems
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• v.15 no.3
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• pp.227-233
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• 2011

The Nramp1/Slc11a1 locus encodes a proton-coupled divalent cation transporter, expressed in late endosomes/lysosomes of macrophages, that constitutes a component of the innate immune response to combat intracellular pathogens and it was shown to play an important role in regulating inherent immunity. The previously identified Z-DNA forming polymorphic repeat(GT)n in the promoter region of the human Nramp1 gene does act as a functional polymorphism influencing gene expression. Research has shown that INF-${\gamma}$, TNF-${\alpha}$, IL-$1{\beta}$ and bacteria LPS increase the level of Nramp1 expression. However, the molecular mechanism for Nramp1 gene regulation is unclear. In this research, bovine Nramp1 5'-flanking region (-1748~+769) was cloned and analyzed by bioinformatics. Then to find the core promoter and the cis-acting elements, deletion analysis of promoter was performed using a set of luciferase reporter gene constructs containing successive deletions of the bovine Nramp1 5'-flanking regions. Promoter activity analysis by the dual luciferase reporter assay system showed that the core promoter of Nramp1 was located at +58~-89 bp. Some positive regulatory elements are located at -89~-205 bp and -278~-1495 bp. And the repressor elements were in region -205~-278 bp, intron1 and -1495~-1748 bp. LPS-responsive regions were located at -1495~-1748 bp and -278~-205 bp. The present study provides an initial effort to explore the molecular mechanism of transcriptional activation of the bovine Nramp1 gene and should facilitate further studies to decode the complex regulatory process and for molecular breeding for disease resistance in bovines.

• The Korean Journal of Mycology
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• v.24 no.3 s.78
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• pp.206-213
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• 1996

Talaromyces luteus 2004, a thermophilic mutant of T. luteus 6112 was obtained by mutagenesis with N-methyl-N'-nitro-N-nitrosoguanidine. T. luteus 2004 produced thermophilic carboxymethylcellulase (CMCase), and other polysaccharide enzymes: avicellase, xylanase, and ${\beta}-glucosidase$. Induction of CMCase production was shown at the highest level in 3% carboxymethylcellulose (CMC) minimal broth, indicating that CMC could work as an inducer. However, glucose and D-cellobiose showed catabolite repression for CMCase production which was under the control of CMC utilization. Optimal conditions for CMCase activity were at $70^{\circ}C$ and pH 4.0, suggesting that CMCase of T. luteus 2004 was a thermophilic enzyme.

• Molecules and Cells
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• v.20 no.2
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• pp.241-246
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• 2005

PDK-1 activates PI3-kinase/Akt signaling and regulates fundamental cellular functions, such as growth and survival. NF-${\kappa}B$ is involved in the induction of a variety of cellular genes affecting immunity, inflammation and the resistance to apoptosis induced by some anti-cancer drugs. Even though the crucial involvement of the PI3-kinase/Akt pathway in the anti-apoptotic activation of NF-${\kappa}B$ is well known, the exact role of PDK-1 as well as PI3-kinase/Akt in NF-vactivation is not understood. Here we demonstrate that PDK-1 plays a pivotal role in transcriptional activation of NF-${\kappa}B$ by dissociating the transcriptional co-repressor HDAC1 from the p65 subunit of NF-${\kappa}B$. The association of CBP with p65 was not directly modulated by PDK-1 or by PI3-kinase. Etoposide activated NF-${\kappa}B$ through PI3-kinase/Akt, and the transcription activation domain (TAD) of p65 was further activated by wild-type PDK-1. Overexpression of a dominant negative PDK-1 mutant decreased etoposide-induced NF-${\kappa}B$ transcription and further down-regulated the ectopic HDAC1-mediated decrease in NF-${\kappa}B$ transcriptional activity. Thus activation of PDK-1 relieves the HDAC1-mediated repression of NF-${\kappa}B$ that may be related to basal as well as activated transcription by NF-${\kappa}B$. This effect may also explain the role of the PI3-kinase/PDK-1 pathway in the anti-apoptotic function of NF-${\kappa}B$ associated with the chemoresistance of cancer cells.

• Molecules and Cells
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• v.41 no.9
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• pp.842-852
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• 2018

Notch signaling is an evolutionarily conserved pathway and involves in the regulation of various cellular and developmental processes. Ligand binding releases the intracellular domain of Notch receptor (NICD), which interacts with DNA-bound CSL [CBF1/Su(H)/Lag-1] to activate transcription of target genes. In the absence of NICD binding, CSL down-regulates target gene expression through the recruitment of various corepressor proteins including SMRT/NCoR (silencing mediator of retinoid and thyroid receptors/nuclear receptor corepressor), SHARP (SMRT/HDAC1-associated repressor protein), and KyoT2. Structural and functional studies revealed the molecular basis of these interactions, in which NICD coactivator and corepressor proteins competitively bind to ${\beta}-trefoil$ domain (BTD) of CSL using a conserved ${\varphi}W{\varphi}P$ motif (${\varphi}$ denotes any hydrophobic residues). To date, there are conflicting ideas regarding the molecular mechanism of SMRT-mediated repression of CSL as to whether CSL-SMRT interaction is direct or indirect (via the bridge factor SHARP). To solve this issue, we mapped the CSL-binding region of SMRT and employed a 'one- plus two-hybrid system' to obtain CSL interaction-defective mutants for this region. We identified the CSL-interaction module of SMRT (CIMS; amino acid 1816-1846) as the molecular determinant of its direct interaction with CSL. Notably, CIMS contains a canonical ${\varphi}W{\varphi}P$ sequence (APIWRP, amino acids 1832-1837) and directly interacts with CSL-BTD in a mode similar to other BTD-binding corepressors. Finally, we showed that CSL-interaction motif, rather than SHARP-interaction motif, of SMRT is involved in transcriptional repression of NICD in a cell-based assay. These results strongly suggest that SMRT participates in CSL-mediated repression via direct binding to CSL.

• Molecules and Cells
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• v.43 no.7
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• pp.607-618
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• 2020

microRNAs (miRNAs) are non-coding RNA molecules involved in the regulation of gene expression. miRNAs inhibit gene expression by binding to the 3' untranslated region (UTR) of their target gene. miRNAs can originate from transposable elements (TEs), which comprise approximately half of the eukaryotic genome and one type of TE, called the long terminal repeat (LTR) is found in class of retrotransposons. Amongst the miRNAs derived from LTR, hsa-miR-3681 was chosen and analyzed using bioinformatics tools and experimental analysis. Studies on hsa-miR-3681 have been scarce and this study provides the relative expression analysis of hsa-miR-3681-5p from humans, chimpanzees, crab-eating monkeys, and mice. Luciferase assay for hsa-miR-3681-5p and its target gene SHISA7 supports our hypothesis that the number of miRNA binding sites affects target gene expression. Especially, the variable number tandem repeat (VNTR) and hsa-miR-3681-5p share the binding sites in the 3' UTR of SHISA7, which leads the enhancer function of hsamiR-3681-5p to inhibit the activity of VNTR. In conclusion, hsa-miR-3681-5p acts as a super-enhancer and the enhancer function of hsa-miR-3681-5p acts as a repressor of VNTR activity in the 3' UTR of SHISA7.

• The Korean Journal of Physiology and Pharmacology
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• v.5 no.6
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• pp.495-501
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• 2001

We have cloned the mouse neurotensin/neuromedin N (NT/N) gene from the murine mast cell line Cl.MC/C57.1 for the first time. The murine NT/N cDNA clone consisted of 765 nucleotides and coded for 169 peptide residues with an N-terminal signal peptide, and the C-terminal region contained of one copy of neurotensin (NT) and one copy of neuromedin N (NN). Total of four Lys-Arg dibasic motifs were present; one each at the middle of the open reading frame, at the N-terminal of NN, at the C-terminal of NT, and between NN and NT. Amino acid sequence analysis of the mouse NT/N revealed 90% homology to that of the rat NT/N gene. NT/N is expressed in murine mast cell lines (Cl.MC/C57.1 and P815), but not in murine bone marrow-derived mast cells (BMMCs), murine macrophage cell line (RAW 264.7), nor in murine T cell line (EL-4). NT/N mRNA in C1.MC/C57.1 is highly inducible by IgE cross-linking, phorbol myristate acetate, neurotensin, and substance P. Following the treatment of demethylating agent, 5-azacytidine (5-azaC), the NT/N gene was induced in BMMCs in response to IgE cross-linking. 5-azaC-treated BMMCs did not express the NT/N gene without additional stimuli. These findings suggested that the regulation of NT/N gene expression was dependent on the effects of not only gene methylation but also enhancer and/or repressor proteins acting on the NT/N promoter.

• IMMUNE NETWORK
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• v.14 no.6
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• pp.321-327
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• 2014

TGF-${\beta}$ induces IgA class switching by B cells. We previously reported that Smad3 and Smad4, pivotal TGF-${\beta}$ signal-transducing transcription factors, mediate germline (GL) ${\alpha}$ transcription induced by TGF-${\beta}1$, resulting in IgA switching by mouse B cells. Post-translational sumoylation of Smad3 and Smad4 regulates TGF-${\beta}$-induced transcriptional activation in certain cell types. In the present study, we investigated the effect of sumoylation on TGF-${\beta}1$-induced, Smad3/4-mediated $GL{\alpha}$ transcription and IgA switching by mouse B cell line, CH12F3-2A. Overexpression of small ubiquitin-like modifier (SUMO)-1, SUMO-2 or SUMO-3 did not affect TGF-${\beta}1$-induced, Smad3/4-mediated $GL{\alpha}$ promoter activity, expression of endogenous $GL{\alpha}$ transcripts, surface IgA expression, and IgA production. Next, we tested the effect of the E3 ligase PIASy on TGF-${\beta}1$-induced, Smad3/4-mediated $GL{\alpha}$ promoter activity. We found that PIASy overexpression suppresses the $GL{\alpha}$ promoter activity in cooperation with histone deacetylase 1. Taken together, these results suggest that SUMO itself does not affect regulation of $GL{\alpha}$ transcription and IgA switching induced by TGF-${\beta}1$/Smad3/4, while PIASy acts as a repressor.

• Molecules and Cells
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• v.21 no.2
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• pp.261-268
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• 2006

The Drosophila methuselah (mth) mutant has an approximately 35 percent increase in average lifespan, and enhanced resistance to various forms of stress, including starvation, high temperature, and dietary paraquat. To examine the transcriptional regulation of mth, we used luciferase assays employing Drosophila S2 cells. Two positive control elements were found at -542 ~ -272 (PE1) and +28 ~ +217 (PE2), where putative binding sites for transcription factors including Dorsal (Dl) were identified. Cotransfection of a Dl expression plasmid with a mth-luciferase reporter plasmid resulted in decreased reporter activity. PE1 and PE2, the minimal elements for strong promoter activity, were required for maximal repression by Dl protein. The N-terminal Rel homology domain (RHD) of Dl was not sufficient for repression of mth. We demonstrated by chromatin affinity precipitation (ChAP) assays in S2 cells that Dl bound to the putative PE1 binding site. Unexpectedly, semi-quantitative RT-PCR analysis revealed that the level of mth transcripts was reduced in dl flies. However, the in vivo result support the view that mth expression is regulated by dl, since it is well known that Dl functions as both a transcriptional activator and repressor depending on what other transcription factors are present. These findings suggest that both innate immunity and resistance to stress are controlled by Dl protein.