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Search Results: 1 - 10 of 3590 matches for " Kwang-Hee Bae "
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Involvement of protein tyrosine phosphatases in adipogenesis: New anti-obesity targets?
Kwang-Hee Bae
BMB Reports , 2012,
Abstract: Obesity is a worldwide epidemic as well as being a major riskfactor for diabetes, cardiovascular diseases and several types ofcancers. Obesity is mainly due to the overgrowth of adiposetissue arising from an imbalance between energy intake andenergy expenditure. Adipose tissue, primarily composed ofadipocytes, plays a key role in maintaining whole body energyhomeostasis. In view of the treatment of obesity andobesity-related diseases, it is critical to understand the detailedsignal transduction mechanisms of adipogenic differentiation.Adipogenic differentiation is tightly regulated by many keysignal cascades, including insulin signaling. These signalcascades generally transfer or amplify the signal by using serialtyrosine phosphorylations. Thus, protein tyrosine kinases andprotein tyrosine phosphatases are closely related to adipogenicdifferentiation. Compared to protein tyrosine kinases, proteintyrosine phosphatases have received little attention inadipogenic differentiation. This review aims to highlight theinvolvement of protein tyrosine phosphatases in adipogenicdifferentiation and the possibility of protein tyrosinephosphatases as drugs to target obesity.
Monitoring of adipogenic differentiation at the single-cell level using atomic force microscopic analysis
Young-Nam Kwon,Won Kon Kim,Sang-Hak Lee,Keewon Kim,Eun Young Kim,Tai Hwan Ha,HyoukSoo Han,Kwang-Hee Bae
Spectroscopy: An International Journal , 2011, DOI: 10.3233/spe-2012-0566
Abstract: Adipogenesis plays an important role in energy homeostasis by storing excess energy as lipid droplets. However, these reservoirs are implicated in a host of major human health problems, such as obesity. Elucidation of the mechanisms underlying adipogenesis is thus crucial to overcome these problems. The preadipocyte cell lines represent an optimal model to examine adipogenesis. Cells differentiate into adipocytes with various speeds of conversion and fat accumulation. Here, we have presented a novel method for detecting adipogenic differentiation at the single-cell level using atomic force microscopic analysis. Data obtained with this method revealed a good correlation between membrane stiffness and the degree of adipogenic differentiation. Although we could not determine the underlying cause for membrane stiffness reduction during adipogenic differentiation, the technique clearly offers advantages over the existing detection systems, such as lipid drop staining and extraction. Furthermore, the degree of adipogenic differentiation at the single-cell level can be detected with this method.
Large-scale preparation of active caspase-3 in E. coli by designing its thrombin-activatable precursors
Hyo Kang, Young-mi Lee, Yu-Jin Jeong, Kyoungsook Park, Mi Jang, Sung Park, Kwang-Hee Bae, Moonil Kim, Sang J Chung
BMC Biotechnology , 2008, DOI: 10.1186/1472-6750-8-92
Abstract: Overproducers of thrombin-activatable full-length caspase-3 precursors were prepared by engineering the auto-activation sites of caspase-3 precursor into a sequence susceptible to thrombin hydrolysis. The engineered precursors were highly expressed as soluble proteins in E. coli and easily purified by affinity chromatography, to levels of 10–15 mg from 1 L of E. coli culture, and readily activated by thrombin digestion. Kinetic evaluation disclosed that thrombin digestion enhanced catalytic activity (kcat/KM) of the precursor proteins by two orders of magnitude.A novel method for a large-scale preparation of active caspase-3 was developed by a strategic engineering to lack auto-activation during expression with amino acid sequences susceptible to thrombin, facilitating high-level expression in E. coli. The precursor protein was easily purified and activated through specific cleavage at the engineered sites by thrombin, generating active caspase-3 in high yields.Multicellular organisms maintain homeostasis through a balance between cell proliferation and death. Apoptosis is a controlled cell death process crucial in a wide range of biological activities, such as normal cell turnover, immune system, embryonic development, metamorphosis, and chemical-dependent cell death [1]. Neuronal death due to aberrant apoptosis underlies the symptoms of various neurological disorders, such as Alzheimer's, Parkinson's and Huntington's diseases, stroke, amyotropic lateral sclerosis (ALS), multiple sclerosis (MS) and spinal muscular atrophy [2]. On the other hand, inactivation of apoptosis by blocking upstream death signals or inhibition of caspase activity by IAP complex formation is central to cancer development and cellular resistance of cells against anticancer agents [3-5].Caspases, a family of cysteine proteases, play crucial roles in apoptosis, pro-inflammatory cytokine activation, and presumably, keratinocyte differentiation [6,7]. Following the initial identification of casp
Selection of Aptamers for Mature White Adipocytes by Cell SELEX Using Flow Cytometry
Eun Young Kim, Ji Won Kim, Won Kon Kim, Baek Soo Han, Sung Goo Park, Bong Hyun Chung, Sang Chul Lee, Kwang-Hee Bae
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0097747
Abstract: Background Adipose tissue, mainly composed of adipocytes, plays an important role in metabolism by regulating energy homeostasis. Obesity is primarily caused by an abundance of adipose tissue. Therefore, specific targeting of adipose tissue is critical during the treatment of obesity, and plays a major role in overcoming it. However, the knowledge of cell-surface markers specific to adipocytes is limited. Methods and Results We applied the CELL SELEX (Systematic Evolution of Ligands by EXponential enrichment) method using flow cytometry to isolate molecular probes for specific recognition of adipocytes. The aptamer library, a mixture of FITC-tagged single-stranded random DNAs, is used as a source for acquiring molecular probes. With the increasing number of selection cycles, there was a steady increase in the fluorescence intensity toward mature adipocytes. Through 12 rounds of SELEX, enriched aptamers showing specific recognition toward mature 3T3-L1 adipocyte cells were isolated. Among these, two aptamers (MA-33 and 91) were able to selectively bind to mature adipocytes with an equilibrium dissociation constant (Kd) in the nanomolar range. These aptamers did not bind to preadipocytes or other cell lines (such as HeLa, HEK-293, or C2C12 cells). Additionally, it was confirmed that MA-33 and 91 can distinguish between mature primary white and primary brown adipocytes. Conclusions These selected aptamers have the potential to be applied as markers for detecting mature white adipocytes and monitoring adipogenesis, and could emerge as an important tool in the treatment of obesity.
Dual-Specificity Phosphatase 10 Controls Brown Adipocyte Differentiation by Modulating the Phosphorylation of P38 Mitogen-Activated Protein Kinase
Hye-Ryung Choi, Won Kon Kim, Eun Young Kim, Baek Soo Han, Jeong-Ki Min, Seung-Wook Chi, Sung Goo Park, Kwang-Hee Bae, Sang Chul Lee
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0072340
Abstract: Background Brown adipocytes play an important role in regulating the balance of energy, and as such, there is a strong correlation between obesity and the amount of brown adipose tissue. Although the molecular mechanism underlying white adipocyte differentiation has been well characterized, brown adipocyte differentiation has not been studied extensively. Here, we investigate the potential role of dual-specificity phosphatase 10 (DUSP10) in brown adipocyte differentiation using primary brown preadipocytes. Methods and Results The expression of DUSP10 increased continuously after the brown adipocyte differentiation of mouse primary brown preadipocytes, whereas the phosphorylation of p38 was significantly upregulated at an early stage of differentiation followed by steep downregulation. The overexpression of DUSP10 induced a decrease in the level of p38 phosphorylation, resulting in lower lipid accumulation than that in cells overexpressing the inactive mutant DUSP10. The expression levels of several brown adipocyte markers such as PGC-1α, UCP1, and PRDM16 were also significantly reduced upon the ectopic expression of DUSP10. Furthermore, decreased mitochondrial DNA content was detected in cells expressing DUSP10. The results obtained upon treatment with the p38 inhibitor, SB203580, clearly indicated that the phosphorylation of p38 at an early stage is important in brown adipocyte differentiation. The effect of the p38 inhibitor was partially recovered by DUSP10 knockdown using RNAi. Conclusions These results suggest that p38 phosphorylation is controlled by DUSP10 expression. Furthermore, p38 phosphorylation at an early stage is critical in brown adipocyte differentiation. Thus, the regulation of DUSP10 activity affects the efficiency of brown adipogenesis. Consequently, DUSP10 can be used as a novel target protein for the regulation of obesity.
Terahertz Wave Approach and Application on FRP Composites
Kwang-Hee Im,David K. Hsu,Chien-Ping Chiou,Daniel J. Barnard
Advances in Materials Science and Engineering , 2013, DOI: 10.1155/2013/563962
Abstract:
Kaurenoic Acid from Aralia continentalis Inhibits Biofilm Formation of Streptococcus mutans
Seung-Il Jeong,Beom-Su Kim,Ki-Suk Keum,Kwang-Hee Lee
Evidence-Based Complementary and Alternative Medicine , 2013, DOI: 10.1155/2013/160592
Abstract:
利用远震接收函数研究黄海周边地区的地壳上地幔结构
Chanho,Yu,Kwang-Hee,Kim,Mancheol,Suh,Bongchool,Suk,Paul,Rydelek,Suyoung,Kang,Yongcheol,Park,刘劲松
地球物理学报 , 2010, DOI: 10.3969/j.issn.0001-5733.2010.06.012
Abstract: 利用宽频带流动台站(YSBSN)记录的远震波形数据和远震接收函数方法,反演了黄海东、西两侧地壳上地幔的S波速度结构.结果表明,莫霍面深度在30~38km之间变化,位于中方一侧的JNN台下方地壳厚度最大,可以归因于华北板块和扬子板块的碰撞;韩方一侧的地壳厚度自北向南逐渐变厚,但仍然难以厘定朝鲜半岛南部潜在碰撞带的位置,这些问题的解决需要更大范围的流动台站观测.由于部分台站位于巨厚的沉积层和多孔的火山岩之上,与浅部构造的相关性使得接收函数表现出较大振幅的混响,从而影响了来自深部结构的转换震相.
Ultrasonic Approach of Rayleigh Pitch-catch Contact Ultrasound Waves on CFRP Laminated Composites

In-Young Yang,Kwang-Hee Im,Uk Heo,David K Hsu,Je-Woong Park,Hak-Joon Kim,Sung-Jin Song,

材料科学技术学报 , 2008,
Abstract: CFRP (carbon fiber reinforced plastics) composite materials have wide applicability because of their inherent design flexibility and improved material properties. However, impacted composite structures have 50%-75% less strength than undamaged structures. In this work, a CFRP composite material was nondestructively characterized in order to ensure product quality and structural integrity of CFRP and one-sided pitch-catch technique was developed to measure impacted-damaged area by using an automated-data acquisition system in an immersion tank. A pitch-catch signal was found to be more sensitive than normal incidence backwall echo of longitudinal wave under defect conditions in the composite.
Host Defense Mechanism-Based Rational Design of Live Vaccine
Yo Han Jang, Young Ho Byun, Kwang-Hee Lee, Eun-Sook Park, Yun Ha Lee, Yoon-Jae Lee, Jinhee Lee, Kyun-Hwan Kim, Baik Lin Seong
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0075043
Abstract: Live attenuated vaccine (LAV), mimicking natural infection, provides an excellent protection against microbial infection. The development of LAV, however, still remains highly empirical and the rational design of clinically useful LAV is scarcely available. Apoptosis and caspase activation are general host antiviral responses in virus-infected cells. Utilizing these tightly regulated host defense mechanisms, we present a novel apoptosis-triggered attenuation of viral virulence as a rational design of live attenuated vaccine with desired levels of safety, efficacy, and productivity. Mutant influenza viruses carrying caspase recognition motifs in viral NP and the interferon-antagonist NS1 proteins were highly attenuated both in vitro and in vivo by caspase-mediated cleavage of those proteins in infected cells. Both viral replication and interferon-resistance were substantially reduced, resulting in a marked attenuation of virulence of the virus. Despite pronounced attenuation, the viruses demonstrated high growth phenotype in embryonated eggs at lower temperature, ensuring its productivity. A single dose vaccination with the mutant virus elicited high levels of systemic and mucosal antibody responses and provided complete protection against both homologous and heterologous lethal challenges in mouse model. While providing a practical means to generate seasonal or pandemic influenza live vaccines, the sensitization of viral proteins to pathogen-triggered apoptotic signals presents a potentially universal, mechanism-based rational design of live vaccines against many viral infections.
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