• Journal of Life Science
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• v.13 no.2
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• pp.184-190
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• 2003

Myxococcus xanthus is a Gram negative, rod-shaped, soil bacterium that displays a social behaviors, and multicellular development upon nutrient deprivation. The csgA gene encoding a cell surface protein is essential for developmental behaviors including rippling, aggregation, fruiting body formation and sporulation. csgA mutants show normal vegetative growth, but lack all these developmental phenotypes. Expression of the CsgA (C-signal) specific genes are eliminated or dramatically reduced in csgA mutants. In order to identify components of C-signal transduction pathway, second site mutations were introduced into csgA mutants and were identified which can fully or partially restore development of csgA mutants (Rhie, H. G. et. al. 1989. J. Bacteriol. 171, 3268-3276). One of such csgA suppressor mutations, socD500 restores only sporulation to csgA mutants at 15$^{\circ}C$. The socD500 mutaion however eliminates the three basic developmental requirements, starvation, high cell density and a solid surface. Only sporulation, not accompanied with fruiting body formation is induced simply by shifting the temperature of vegetatively growing cells from $32^{\circ}C$ to $15^{\circ}C$. Spores induced by socD500 mutation is not as thick as that of wild-type fruiting body. In socD500 genetic background, two of ten C-signal dependent genes, $\Omega$DK4506 and $\Omega$DK4406 are more highly expressed in growing cells at $15^{\circ}C$. These results indicate that the socD500 mutation may be partly involved in the regulation of expression of two C-signal dependent genes and genes for sporulation in this transduction pathway.

• Proceedings of the Microbiological Society of Korea Conference
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• 2002.10a
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• pp.203-205
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• 2002

Light is an environmental signal that regulates photomovement and main energy source of photosynthesis in the cyanobacterium Synechocystis sp. PCC 6803 (Syn6803). Syn6803 is a popular model system for study of plant functional genomics. In this report, we adopted 2D gel based proteomics study to investigate proteins related with the light absorption and photo-protection in Syn6803. More than 700 proteins were detected on the SDS-gels stained with silver nitrate. Several proteins showing different expression level under various light conditions were identified with MALDI-TOF Mass spectrometry. As a comparison, we also conducted ICAT-based proteome study using WT and cphl (cyanobacterial phytochrome 1) mutant. A cphl deletion led to changes in the expression of proteins involved in translation, photosynthesis including photosystem and CO2 fixation, and cellular regulation. We are currently involved in TAP-tagging method to study protein-protein interactions in search for the molecular component involved in the light signal transduction of Syn6803 photomovement.

• The Plant Pathology Journal
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• v.27 no.2
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• pp.103-109
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• 2011

The fungal genus Cercospora is one of the most ubiquitous groups of plant pathogenic fungi, and gray leaf spot caused by C. zeae-maydis is one of the most widespread and damaging foliar diseases of maize in the world. While light has been implicated as a critical environmental regulator of pathogenesis in C. zeae-maydis, the relationship between light and the development of disease is not fully understood. Recent discoveries have provided new insights into how light influences pathogenesis and morphogenesis in C. zeae-maydis, particularly at the molecular level. This review is focused on integrating old and new information to provide an updated perspective of how light influences pathogenesis, and provides a working model to explain some of the underlying molecular mechanisms. Ultimately, a thorough molecular-level understanding of how light regulates pathogenesis will augment efforts to manage gray leaf spot by improving host resistance and disease management strategies.

• Proceedings of the Korean Society of Life Science Conference
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• 2008.10a
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• pp.86.2-86.2
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• 2008

• Tuberculosis and Respiratory Diseases
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• v.43 no.2
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• pp.123-127
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• 1996

Secretion of surfactant phospholipid can be stimulated by a variety of agonists acting via at least three different signal transduction mechanisms. These include the adenylate cyclase system with activation of cAMP-dependent protein kinase; activation of protein kinase C either directly or subsequent to activation of phosphoinositide-specific phospholipase C and generation of diacylglycerols and inositol trisphosphate; and a third mechanism that involves incresed $Ca^{2+}$ levels and a calmodulin-dependent step. ATP stimulates secretion via all three mechanisms. The protein kinase C pathway is also coupled to phopholipase D which, acting on relatively abundant cellular phospholipids, generates diacylglycerols that further activate protein kinase C. Sustained protein kinase C activation can maintain phosphatidylcholine secretion for a prolonged period of time. It is likely that interactions between the different signaling pathways have an important role in the overall physiological regulation of surfactant secretion.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.2
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• pp.114-121
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• 2013

High efficiency operation is required for motors of vehicle to increase fuel efficiency due to the regulation of exhaust gas. This paper presents a control method of fuel pressure to increase fuel efficiency and a sensorless control method of BLDC motor to get higher efficiency than conventional brushed DC motor. Initial rotor position of BLDC motor is detected from current value that is occurred by test voltage pulse and rotor is accelerated by defined sequence to enter sensorless operation mode. The algorithm to control flow rate of fuel pump uses PI controller that is control motor speed to maintain the target fuel pressure commanded by ECU.

• Asian-Australasian Journal of Animal Sciences
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• v.26 no.8
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• pp.1189-1196
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• 2013

Adipose tissue development and function play a critical role in the regulation of energy balance, lipid metabolism, and the pathophysiology of metabolic syndromes. Although the effect of zinc ascorbate supplementation in diabetes or glycemic control is known in humans, the underlying mechanism is not well described. Here, we investigated the effect of a zinc-chelated vitamin C (ZnC) compound on the adipogenic differentiation of 3T3-L1 preadipocytes. Treatment with ZnC for 8 d significantly promoted adipogenesis, which was characterized by increased glycerol-3-phosphate dehydrogenase activity and intracellular lipid accumulation in 3T3-L1 cells. Meanwhile, ZnC induced a pronounced up-regulation of the expression of glucose transporter type 4 (GLUT4) and the adipocyte-specific gene adipocyte protein 2 (aP2). Analysis of mRNA and protein levels further showed that ZnC increased the sequential expression of peroxisome proliferator-activated receptor gamma ($PPAR{\gamma}$) and CCAAT/enhancer-binding protein alpha (C/$EBP{\alpha}$), the key transcription factors of adipogenesis. These results indicate that ZnC could promote adipogenesis through $PPAR{\gamma}$ and C/$EBP{\alpha}$, which act synergistically for the expression of aP2 and GLUT4, leading to the generation of insulin-responsive adipocytes and can thereby be useful as a novel therapeutic agent for the management of diabetes and related metabolic disorders.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.4
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• pp.370-377
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• 2001

Flounder brain cytosol contains protein inhibitors that markedly inhibit the activity of partially purified brain membrane phospholipase D (PLD) which is dependent on phosphatidylinositol 4,5-bisphosphate ($PIP_2$) but insensitive to ADP-ribosylation factor (ARF), The PLD inhibitors have been enriched through several chromatographic steps and characterized with respect to size and mechanism of inhibition. Sequential chromatography of the brain cytosol yielded six inhibitor fractions, Two (IIA and IIB) of six inhibitor fractions showed the $PIP_2$-phosphatase activities. IIA was identified as synaptojanin, a nerve terminal protein that has known to be a member of the inositolpolyphosphate 5-phosphatase family, by immunoblot analysis. IIB showed an apparent molecular mass of 158 kDa by Superose 12 gel filtration chromatography and was immunologically distinct from synaptojanin. IIB hydrolyzed $PIP_2$, yielding only phosphatidylinositol phosphate (PIP) as product, suggesting that IIB hydrolyzes only one phosphate from either the 4- or 5-position of PI (4,5)$P_2$. These studies demonstrate that the existence of multiple $PIP_2$-phosphatases have been implicated in the negative regulation of $PIP_2$-dependent PLD activity within flounder brain.

• YAKHAK HOEJI
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• v.48 no.6
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• pp.358-363
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• 2004

Matrix metalloproteinases (MMPs) are known to play an important role in photoaging by mediating the degradation of extracellular matrix proteins. In this study, to develop a n ew anti-aging agent, we investigated the antioxidant activity and the inhibitory effect of Melothria heterophylla extract on expression of MMP-1 in UVA-irradiated human dermal fibroblasts and MMP-1 activity. The M.heterophylla extract was found to scavenge radicals and reactive oxygen species (ROS) with the $SC_{50}$ values of $13{\mu}g/ml$ against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals and $20{\mu}g/ml$ against superoxide radicals in the xanthine/xanthine oxidase system, respectively. UVA-induced MMP-1 expression was reduced about 80% by $100{\mu}g/ml$ of the M.heterophylla extract but MMP-1 Mrna expression was not inhibited. Therefore, we conclude that the M.heterophylla extract significantly inhibits MMP-1 expression at the protein level. Also, the M.heterophylla extract inhibited MMP-1 activity in a dose dependent manner. From these results, we suggest that the M.heterophylla extract can be used as a new anti-aging agent by antioxidant activity, regulation of UVA-induced MMP-1 production, and inhibition of MMP-1 activity.

• Genomics & Informatics
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• v.21 no.2
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• pp.19.1-19.13
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• 2023

Liver cancer, particularly hepatocellular carcinoma (HCC), poses a significant global threat to human lives. To advance the development of innovative diagnostic and treatment approaches, it is essential to examine the hidden features of HCC, particularly its 3D genome architecture, which is not well understood. In this study, we investigated the 3D genome organization of four HCC cell lines-Hep3B, Huh1, Huh7, and SNU449-using in situ Hi-C and assay for transposase-accessible chromatin sequencing. Our findings revealed that HCC cell lines had more long-range interactions, both intra-and interchromosomal, compared to human mammary epithelial cells (HMECs). Unexpectedly, HCC cell lines displayed cell line-specific compartmental modifications at the megabase (Mb) scale, which could potentially be leveraged in determining HCC subtypes. At the sub-Mb scale, we observed decreases in intra-TAD (topologically associated domain) interactions and chromatin loops in HCC cell lines compared to HMECs. Lastly, we discovered a correlation between gene expression and the 3D chromatin architecture of SLC8A1, which encodes a sodium-calcium antiporter whose modulation is known to induce apoptosis by comparison between HCC cell lines and HMECs. Our findings suggest that HCC cell lines have a distinct 3D genome organization that is different from those of normal and other cancer cells based on the analysis of compartments, TADs, and chromatin loops. Overall, we take this as evidence that genome organization plays a crucial role in cancer phenotype determination. Further exploration of epigenetics in HCC will help us to better understand specific gene regulation mechanisms and uncover novel targets for cancer treatment.