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Sungok Kim,Jisuk Jeung,Eunjoo H. Lee,Yunghyun Choi 한국식품영양과학회 2021 한국식품영양과학회 학술대회발표집 Vol.2021 No.10
This study investigated the effects of Corni Fructus water extract (CFE) against oxidative stress-induced cell damage in C2C12. The results demonstrated that preincubation of C2C12 with CFE prior to H₂O₂ stimulation inhibited cytotoxicity, comet tail formation, chromatin condensation and phospho-histone γH2AX expression, suggesting that it prevents H₂O₂-induced ROS accumulation, cellular DNA damage and apoptotic cell death. CFE also restored H₂O₂-induced mitochondrial dysfunction and prevented apoptosis by Bax/Bcl-2 ratio and inducing cytosolic release of cytochrome c and degradation of caspase and PARP in H₂O₂-stimulated C2C12. Interestingly, the expression of Nrf2 was significantly increased by CFE in the presence of H₂O₂, which was associated with a marked increase in expression of HO-1. Additionally, the preventive effects of CFE were significantly abolished by zinc protoporphyrin, a HO-1 specific inhibitor, indicating that CFE activates the Nrf2/HO-1 axis in C2C12 to protect against oxidative stress. These findings suggest that CFE may protect muscle cells against oxidative stress-induced injury through activation of the Nrf2/HO-1 signaling pathway.
Molecular Mechanisms of Microglial Deactivation by TGF-β-inducible Protein βig-h3
Mi-Ok Kim,Eunjoo H. Lee 한국통합생물학회 2005 Animal cells and systems Vol.9 No.2
βig-h3 is a secretory protein that is induced by TGF- and implicated in various disease conditions including fibrosis. We have previously reported that ig-h3 expression is implicated in astrocyte response to brain injury. In this study, we further investigated potential roles of ig-h3 protein in the injured central nervous system (CNS). We specifically assessed whether the treatment of microglial cells with ig-h3 can regulate microglial activity. Microglial cells are the prime effector cells in CNS immune and inflammatory responses. When activated, they produce a number of inflammatory mediators, which can promote neuronal injury. We prepared conditioned medium from the stable CHO cell line transfected with human ig-h3 cDNA. We then examined the effects of the conditioned medium on the LPS- or IFN--mediated induction of proinflammatory molecules in microglial cells. Preincubation with the conditioned medium significantly attenuated LPS-mediated upregulation of TNF-, IL-1, iNOS and COX-2 mRNA expression in BV2 murine microglial cells. It also reduced IFN--mediated upregulation of TNF- and COX-2 mRNA expression but not iNOS mRNA expression. Assays of nitric oxide release correlated with the mRNA data, which showed selective inhibition of LPS-mediated nitric oxide production. Although the regulatory mechanisms need to be further investigated, these results suggest that astrocyte-derived ig-h3 may contribute to protection of the CNS from immune-mediated damage via controlling microglial inflammatory responses.
Jung, Hana,Lee, Eunjoo H.,Lee, Tae Hoon,Cho, Man-Ho MDPI 2016 INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES Vol.17 No.9
<P>Solar ultraviolet (UV) radiation is a main extrinsic factor for skin aging. Chronic exposure of the skin to UV radiation causes the induction of matrix metalloproteinases (MMPs), such as MMP-1, and consequently results in alterations of the extracellular matrix (ECM) and skin photoaging. Flavonoids are considered as potent anti-photoaging agents due to their UV-absorbing and antioxidant properties and inhibitory activity against UV-mediated MMP induction. To identify anti-photoaging agents, in the present study we examined the preventative effect of methoxyflavonoids, such as sakuranetin, isosakuranetin, homoeriodictyol, genkwanin, chrysoeriol and syringetin, on UV-B-induced skin photo-damage. Of the examined methoxyflavonoids, pretreatment with isosakuranetin strongly suppressed the UV-B-mediated induction of MMP-1 in human keratinocytes in a concentration-dependent manner. Isosakuranetin inhibited UV-B-induced phosphorylation of mitogen-activated protein kinase (MAPK) signaling components, ERK1/2, JNK1/2 and p38 proteins. This result suggests that the ERK1/2 kinase pathways likely contribute to the inhibitory effects of isosakuranetin on UV-induced MMP-1 production in human keratinocytes. Isosakuranetin also prevented UV-B-induced degradation of type-1 collagen in human dermal fibroblast cells. Taken together, our findings suggest that isosakuranetin has the potential for development as a protective agent for skin photoaging through the inhibition of UV-induced MMP-1 production and collagen degradation.</P>
Room-Temperature Synthesis of Widely Tunable Formamidinium Lead Halide Perovskite Nanocrystals
Minh, Duong Nguyen,Kim, Juwon,Hyon, Jinho,Sim, Jae Hyun,Sowlih, Haneen H.,Seo, Chunhee,Nam, Jihye,Eom, Sangwon,Suk, Soyeon,Lee, Sangheon,Kim, Eunjoo,Kang, Youngjong American Chemical Society 2017 Chemistry of materials Vol.29 No.13
<P>Colloidal perovskite nanocrystals based on formamidinium lead halide (FAPbX(3)) have been synthesized by the ligand-assisted reprecipitation method using PbX2-dimethyl sulfoxide complexes as precursors at room temperature. Well-defined cubicshaped FAPbX(3) nanocrystals have been obtained with a size d of similar to 10 nm. The synthesized FAPbX(3) nanocrystals show bright photoluminescence with a high photoluminescence quantum yield (75% for FAPbBr(3)). The lifetimes of FAPbBr(3) nanocrystals were measured for the samples isolated at several different centrifugal speeds. The photoluminescence can be tuned from the blue to near infrared region (lambda(peak) = 408-784 nm) by changing either the amount of oleylamine or the composition of X. The color expression range is 135% of the NTSC standard. The bandwidth of the photoluminescence spectra of FAPbX(3) nanocrystals is narrow (full width at half-maximum of 18-48 nm). FAPbX(3) nanocrystals show thermal stability that is better than that of MAPbBr(3) nanocrystals.</P>
Hahm, Dae Hyun,Yeom, Mi Jung,Ko, Whae Min,Lee, Eunjoo H.,Lee, Hye Jung,Shim, In Sop,Kim, Hong Yeoul 한국미생물 · 생명공학회 2002 Journal of microbiology and biotechnology Vol.12 No.1
A 1,989-bp genomic region encoding nickel resistance genes was isolated from Legionella pneumophila, a pathogen for legionellosis. From a sequencing and computer analysis, the region was found to harbor two structural genes, a nreB-like protein gene (1,149 bp) and a nreA-like protein gene (270 bp), in a row. Both genes exhibited a significant degree of similarity to the corresponding genes from Synechocystis sp. PCC6803 (54% amino acid sequence identity) and Achromobacter xylosoxidans 31A (76%). The gene was successfully expressed in E. coli MG1655 and conferred a nickel resistance of up to 5mM in an LB medium and 3 mM in a TMS medium including gluconate as the sole carbon source. E. coli harboring the nickel resistance gene also exhibited a substantial resistance to cobalt, yet no resistance to cadmium or zinc. Since the extracellular concentration of nickel remained constant during the whole period of cultivation, it was confirmed that the nickel resistance was provided by an efflux system like the Ni^2+ permease (nrsD) of Synechocystis sp. strain PCC6803. Since polyphosphate (poly-P) is known as a global regulator for gene expression as well as a potential virulence factor in E. coli, the nickel resistance of a ppk mutant of E. coli MG1655 harboring the nickel resistance gene from L. pneumophila was compared with that of its parental strain. The nickel resistance was significantly attenuated by ppk inactivation, which was more pronounced in an LB medium than in a TMS medium.
Down-regulation of Mortalin Exacerbates Aβ-mediated Mitochondrial Fragmentation and Dysfunction
Park, So Jung,Shin, Ji Hyun,Jeong, Jae In,Song, Ji Hoon,Jo, Yoon Kyung,Kim, Eun Sung,Lee, Eunjoo H.,Hwang, Jung Jin,Lee, Eun Kyung,Chung, Sun Ju,Koh, Jae-Young,Jo, Dong-Gyu,Cho, Dong-Hyung American Society for Biochemistry and Molecular Bi 2014 The Journal of biological chemistry Vol.289 No.4
<P>Mitochondrial dynamics greatly influence the biogenesis and morphology of mitochondria. Mitochondria are particularly important in neurons, which have a high demand for energy. Therefore, mitochondrial dysfunction is strongly associated with neurodegenerative diseases. Until now various post-translational modifications for mitochondrial dynamic proteins and several regulatory proteins have explained complex mitochondrial dynamics. However, the precise mechanism that coordinates these complex processes remains unclear. To further understand the regulatory machinery of mitochondrial dynamics, we screened a mitochondrial siRNA library and identified mortalin as a potential regulatory protein. Both genetic and chemical inhibition of mortalin strongly induced mitochondrial fragmentation and synergistically increased Aβ-mediated cytotoxicity as well as mitochondrial dysfunction. Importantly we determined that the expression of mortalin in Alzheimer disease (AD) patients and in the triple transgenic-AD mouse model was considerably decreased. In contrast, overexpression of mortalin significantly suppressed Aβ-mediated mitochondrial fragmentation and cell death. Taken together, our results suggest that down-regulation of mortalin may potentiate Aβ-mediated mitochondrial fragmentation and dysfunction in AD.</P>
Yu-Ji Lim,강동호,Sang Keun Ha,오명숙,Seong Min Kim,Sun Yeou Kim,Eunjoo H. Lee,윤태진,강철훈,박지호 대한약학회 2009 Archives of Pharmacal Research Vol.32 No.3
Arbutin has been used as a whitening agent in cosmetic products. Melanin, the major pigment that gives color to skin, may be over-produced with sun exposure or in conditions such as melasma or hyperpigmentary diseases. Tyrosinase is a key enzyme that catalyzes melanin synthesis in melanocytes; therefore, inhibitors of the tyrosinase enzyme could be used for cosmetic skin whitening. A recent study has reported that arbutin decreases melanin biosynthesis through the inhibition of tyrosinase activity. However, this inhibitory mechanism of arbutin was not sufficiently demonstrated in skin tissue models. We found that arbutin both inhibits melanin production in B16 cells induced with α-MSH and decreases tyrosinase activity in a cell-free system. Furthermore, the hyperpigmentation effects of α-MSH were abrogated by the addition of arbutin to brownish guinea pig and human skin tissues. These results suggest that arbutin may be a useful agent for skin whitening.