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Yanggu, South Korea

Yim S.-H.,Sookmyung Womens University | Jung S.,Sookmyung Womens University | Lee S.-K.,Sookmyung Womens University | Cheon C.-I.,Sookmyung Womens University | And 4 more authors.
Journal of Industrial Microbiology and Biotechnology | Year: 2011

Corynebacterium glutamicum, a Gram-positive bacterium, has been widely used for industrial amino acid production. We previously showed that, in C. glutamicum, argCJBDFRGH arginine biosynthesis genes are clustered but independently transcribed from argC and argG promoters, leading to the generation of two transcripts corresponding to argCJBDFR and argGH. In this report, we show the effect of the C. glutamicum ArgR repressor on argC and argG promoters by overexpressing or disrupting the argR gene. Gel filtration assay results indicate that native ArgR is a hexamer of equal subunits with molecular mass of 110 kDa. Protein sequence analysis revealed the presence of an "SR" (Ser 57-Arg 58) motif for the DNA binding site at the N-terminal region and the "GTIAGDDTV" motif for arginine binding and its oligomerization at the C-terminal region. An argC or argG promoter-lacZ fusion reporter assay and argR mutational analysis showed that transcription of the argCJBDFR arginine biosynthesis genes is regulated from the argC promoter by ArgR in cooperation with l-arginine in C. glutamicum. This finding was supported by the gel mobility-shift assay showing direct binding of hexameric ArgR to the argC promoter in the presence of l-arginine. Unexpectedly, argGH transcription was not responsive to the level of ArgR repressor and/or arginine. In a further study, a C. glutamicum argR mutant was constructed by disrupting the chromosomal argR gene to manufacture an improved arginine-producing strain. Arginine productivity was increased in the C. glutamicum argR mutant strain under conditions of both limited and excessive arginine. © 2011 Society for Industrial Microbiology. Source

Jung S.,Sookmyung Womens University | Jeong H.-K.,Sookmyung Womens University | Shin J.,Songdo Technopark | Lee M.-S.,Sookmyung Womens University
International Journal of Oncology | Year: 2011

Breast cancer is one of the most common cancers in women and it is highly treatable by radiotherapy and/or radiochemotherapy. A global analysis of the protein expression pattern was performed to identify radiation-responsive proteins in MCF-7 breast cancer cells using 2D-PAGE coupled with MALDI-TOF-MS. When MCF-7 cells were exposed to ionizing radiation (IR) such as γ-rays, eight proteins (GH2, RGS17, BAK1, CCNH, TSG6, RAD51B, IGFBP1, and CASP14) were up-regulated and three proteins (C1QRF, PLSCR2, and p34 SE1-1) were down-regulated. In an effort to find what mechanisms are responsible for these changes, we initially focused on p34 SE1-1, which is known as a transcriptional regulator and oncogene. Our results show that p34 SE1-1 expression is significantly decreased only at the protein level but not at the transcriptional level after IR treatment. We suggest that the B55 regulatory subunit of PP2A, a positive regulator of p34 SE1-1, is at least partly responsible for the decreased p34 SE1-1 expression, in which the B55 regulatory subunit of PP2A was down-regulated at the protein level as a cellular response to IR. We, therefore, propose that inactivated PP2A resulting from the absence of the B55 subunit may not be able to dephosphorylate p34 SE1-1 and therefore increase the phosphorylated form of p34 SE1-1 with low stability. Our further extended study shows that the p34 SE1-1 expression level was not changed after H 2O 2 treatment at either protein or transcriptional levels. This result implies that MCF-7 cells seem to use different signaling pathways in response to IR and H 2O 2 stresses although both of them belong to the same DNA damage inducing stimuli of reactive oxygen species (ROS). Copyright © 2011 Spandidos Publications Ltd. All rights reserved. Source

This paper describes a simple new approach toward improving resolution of two-dimensional (2-D) protein gels used to explore the mammalian proteome. The method employs sample prefractionation using solution-phase isoelectric focusing (IEF) to split the mammalian proteome into well-resolved pools. As crude samples are thus prefractionated by pI range, very-narrow-pH-range 2-D gels can be subsequently employed for protein separation. Using custom pH partition membranes and commercially available immobilized pH gradient (IPG) strips, we maximized the total separation distance and throughput of seven samples obtained by prefractionation. Both protein loading capacity and separation quality were higher than the values obtained by separation of fractionated samples on narrow-pH-range 2-D gels; the total effective IEF separation distance was ~82 cm over the pH range pH 3-10. This improved method for analyzing prefractionated samples on narrow-pH-range 2-D gels allows high protein resolution without the use of large gels, resulting in decreased costs and run times. © 2009 Springer-Verlag. Source

Jung S.,Sookmyung Womens University | Yi L.,Sookmyung Womens University | Kim J.,Sookmyung Womens University | Jeong D.,Soonchunhyang University | And 6 more authors.
Molecules and Cells | Year: 2011

Multiple cytosine guanine dinucleotides (CpG island) are found in the VIM promoter region. The levels of VIM promoter methylation and VIM gene expression were investigated in 7 cervical cancer cell lines and 50 human tissue samples with a distinctive degree of malignant trans-formation. While multiple CpG sites in the VIM promoter were highly methylated in CIN III and invasive carcinoma cells, they were rarely methylated in normal cells. Our result shows that methylation in the VIM promoter appears to start from CIN I and CIN II, relatively early stages of multistep carcinogenesis. This epigenetic alteration in VIM promoter suggests the availability as a biomarker for the early diagnosis and prevention of cervical cancer. We also show that hypermethylation in the VIM promoter is responsible for transcriptional silencing of the VIM gene in cervical cancer cells. In addition, our result shows that exogenous overexpression of the VIM gene in SiHa cervical cancer cells slightly activated cell proliferation and migration as shown in soft agar colony formation and migration assays. © 2011 KSMCB. Source

Moon H.-I.,Kangwon National University | Kim H.,Songdo Technopark | Kim S.B.,LG Corp | Kim D.H.,Seal Design Team | Kim H.Y.,Kangwon National University
Finite Elements in Analysis and Design | Year: 2011

Automotive door seals are intended to prevent dust and water inflow from outside and isolate noise. To achieve these design targets, a door seal should have a reaction force higher than a specific criterion, while the effort to close the door requires a minimum reaction force. A door-seal design can be defined as a process of compromise between these two reciprocal design targets. Door-closing velocity involves a number of factors, including the door seal, and to date has only been evaluated using experimental methods. Experimental methods make it difficult to determine the main factors in door-closing effort, and are not particularly helpful to the development of optimized seal design. Computational efforts toward door-seal design have only focused on drawings and structural analysis. This paper develops a numerical process to predict minimum door-closing velocity from both a real vehicle's geometrical/physical data and virtual reaction force versus closing time data. A three-dimensional door-closing analysis, using explicit code was introduced to produce a more realistic solution. © 2010 Elsevier B.V. All rights reserved. Source

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