• Animal cells and systems
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• 제13권4호
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• pp.405-409
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• 2009

When DNA double-strand breaks (DSBs) were induced in mammalian cells, many DNA damage response proteins are accumulated at damage sites to form nuclear foci called IR-induced foci. Although the formation of foci has been shown to promote repair efficiency, the structural organization of chromatin in foci remains obscure. BAF53 is an actin-related protein which is required for maintenance of chromosome territory. In this study, we show that the formation of IR-induced foci by $\gamma$-H2AX and 53BP1 were reduced when BAF53 is depleted, while DSB- activated ATM pathway and the phosphorylation of H2AX remains intact after DNA damage in BAF53 knockdown cells. We also found that DSB repair efficiency was largely compromised in BAF53 knockdown cells. These results indicate that BAF53 is critical for formation of foci by $\gamma$-H2AX decorated chromatin at damage sites and the structural organization of chromatin in foci is an important factor to achieve the maximum efficiency of DNA repair.

• BMB Reports
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• 제34권6호
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• pp.489-495
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• 2001

DNA damage by UV and environmental agents are the major cause of genomic instability that needs to be repaired, otherwise it give rise to cancer. Accordingly, mammalian cells operate several DNA repair pathways that are not only responsible for identifying various types of DNA damage but also involved in removing DNA damage. In mammals, nucleotide excision repair (NER) machinery is responsible for most, if not all, of the bulky adducts caused by UV and chemical agents. Although most of the proteins involved in NER pathway have been identified, only recently have we begun to gain some insight into the mechanism by which proteins recognize damaged DNA. Binding of Xeroderma pigmentosum group C protein (XPC)-hHR23B complex to damaged DNA is the initial damage recognition step in NER, which leads to the recruitment of XPA and RPA to form a damage recognition complex. Formation of damage recognition complex not only stabilizes low affinity binding of XPA to the damaged DNA, but also induces structural distortion, both of which are likely necessary for the recruitment of TFIIH and two structure-specific endonucleases for dual incision.

• BMB Reports
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• 제54권9호
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• pp.458-463
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• 2021

Cytokines activate inflammatory signals and are major mediators in progressive β-cell damage, which leads to type 1 diabetes mellitus. We recently showed that the cell-permeable Tat-CIAPIN1 fusion protein inhibits neuronal cell death induced by oxidative stress. However, how the Tat-CIAPIN1 protein affects cytokine-induced β-cell damage has not been investigated yet. Thus, we assessed whether the Tat-CIAPIN1 protein can protect RINm5F β-cells against cytokine-induced cytotoxicity. In cytokine-exposed RINm5F β-cells, the transduced Tat-CIAPIN1 protein elevated cell survivals and reduced reactive oxygen species (ROS) and DNA fragmentation levels. The Tat-CIAPIN1 protein reduced mitogen-activated protein kinases (MAPKs) and NF-κB activation levels and elevated Bcl-2 protein, whereas Bax and cleaved Caspase-3 proteins were decreased by this fusion protein. Thus, the protection of RINm5F β-cells by the Tat-CIAPIN1 protein against cytokine-induced cytotoxicity can suggest that the Tat-CIAPIN1 protein might be used as a therapeutic inhibitor against RINm5F β-cell damage.

• Rapid Communication in Photoscience
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• 제4권2호
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• pp.37-40
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• 2015

To examine the photosensitized biomolecules damaging activity, dimethoxyP(V)tetrakis(2-naphthyl)porphyrin (NP) and dimethoxyP(V)tetraphenylporphyrin (PP) were synthesized. The naphthyl moiety of NP hardly deactivated the photoexcited P(V)porphyrin ring in ethanol. In aqueous solution, the naphthyl moiety showed the quenching effect on the photoexcited porphyrin ring, possibly through electron transfer and self-quenching by a molecular association. Binding interaction between human serum albumin (HSA), a water soluble protein, and these porphyrins could be confirmed by the absorption spectral change. The apparent association constant of NP was larger than that of PP. It is explained by that more hydrophobic NP can easily bind into the hydrophobic pockets of HSA. The photoexcited PP effectively induced damage of the tryptophan residue of HSA, through electron transfer-mediated oxidation and singlet oxygen generation. NP also induced HSA damage during photo-irradiation and the contributions of the electron transfer and singlet oxygen mechanisms were speculated. The electron transfer-mediated mechanism to the photosensitized protein damage should be advantageous for photodynamic therapy in hypoxic condition. The quantum yield of the HSA photodamage by PP was significantly larger than that of NP. The quenching effect of the naphthyl moiety is considered to suppress the photosensitized protein damage. In conclusion, the naphthalene substitution to the P(V)porphyrins can enhance the binding interaction with hydrophobic biomacromolecules such as protein, however, this substitution may reduce the photodynamic effect of P(V)porphyrin ring in aqueous media.

• Korea Journal of Cosmetic Science
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• 제2권1호
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• pp.1-10
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• 2020

Protection mechanisms for skin damage of ultraviolet (UV) absorbers in personal care products for protection against UV are well studied, but not for hair protection. The purpose of this study is to describe and compare the changes of physical property produced in human hair by doses of the UV-B exposure causing protein degradation. To observe the change of physical properties in hair, the experimental intensity of UV-B exposure has been established on the basis of statistical data from official meterological administration as daily one hour sunlight exposure for two weeks. Polysilicone-15, ethylhexyl methoxycinnamate (OMC), and octocrylene were employed for UV-B absorber, and those were treated to hair swatch by rubbing wash through shampoo and conditioner. Bending rigidity displayed kinetically successive reduction at high doses of UV exposure up to the 8,000 s, and exhibited different level at each sample of UV-B absorber. However, the values of Bossa Nova Technologies (BNT) for shinning factor were already saturable at the 2,000 s exposure except that treated with polysilicone-15. The differential scanning calorimetry (DSC) to measure a strength of inner protein produces a successive reduction of enthalpy as like a reduction of bending rigidity upon UV exposure. Surface roughness from lateral force microscope (LFM) acquired immediately after UV exposure show a saturable frictional voltage which has been also found in a saturable BNT data as the time of UV exposure increases. Through researching the DSC and the LFM, shinning of hair was much correlated to the protein damage at the surface, and bending rigidity could be regulated by the protein structural damage inside hair. Therefore, the optimization of efficient strategy for simultaneous prevention of hair protein on the surface and internal hair was required to maintain physical properties against UV.

• Molecules and Cells
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• 제38권8호
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• pp.697-704
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• 2015

Deleted in breast cancer-1 (DBC1) contributes to the regulation of cell survival and apoptosis. Recent studies demonstrated that DBC is phosphorylated at Thr454 by ATM/ATR kinases in response to DNA damage, which is a critical event for p53 activation and apoptosis. However, how DBC1 phosphorylation is regulated has not been studied. Here we show that protein phosphatase 4 (PP4) dephosphorylates DBC1, regulating its role in DNA damage response. PP4R2, a regulatory subunit of PP4, mediates the interaction between DBC1 and PP4C, a catalytic subunit. PP4C efficiently dephosphorylates pThr454 on DBC1 in vitro, and the depletion of PP4C/PP4R2 in cells alters the kinetics of DBC1 phosphorylation and p53 activation, and increases apoptosis in response to DNA damage, which are compatible with the expression of the phosphomimetic DBC-1 mutant (T454E). These suggest that the PP4-mediated dephosphorylation of DBC1 is necessary for efficient damage responses in cells.

• 한국자기공명학회논문지
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• 제20권4호
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• pp.138-142
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• 2016

Replication Protein A (RPA) is the eukaryotic single-stranded DNA binding protein. It involves in DNA replication, repair, and damage response. Among three subunits, RPA70 has a protein-protein binding domain (RPA70N) at the N-terminal. It has known that the domain recruits several damage response proteins to the damaged site. Also, it is suggested that there are more candidates that interact with RPA70N. Even though several studies performed on the structural aspects of RPA70N and its ligand binding, the backbone assignments of RPA70N is not available in public. In this study, we present the backbone assignments of RPA70N.

• Archives of Plastic Surgery
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• 제40권5호
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• pp.517-521
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• 2013

Background Diabetes is characterized by chronic hyperglycemia, which can increase reactive oxygen species (ROS) production by the mitochondrial electron transport chain. The formation of ROS induces oxidative stress and activates oxidative damage-inducing genes in cells. No research has been published on oxidative damage-related extracellular superoxide dismutase (EC-SOD) protein levels in human diabetic skin. We investigated the expression of EC-SOD in diabetic skin compared with normal skin tissue in vivo. Methods The expression of EC-SOD protein was evaluated by western blotting in 6 diabetic skin tissue samples and 6 normal skin samples. Immunohistochemical staining was also carried out to confirm the EC-SOD expression level in the 6 diabetic skin tissue samples. Results The western blotting showed significantly lower EC-SOD protein expression in the diabetic skin tissue than in the normal tissue. Immunohistochemical examination of EC-SOD protein expression supported the western blotting analysis. Conclusions Diabetic skin tissues express a relatively small amount of EC-SOD protein and may not be protected against oxidative stress. We believe that EC-SOD is related to the altered metabolic state in diabetic skin, which elevates ROS production.

• The Korean Journal of Physiology and Pharmacology
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• 제27권5호
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• pp.427-436
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• 2023

Mitotic arrest deficient 2 like 2 (Mad2L2, also known as Mad2B), the human homologue of the yeast Rev7 protein, is a regulatory subunit of DNA polymerase ζ that shares high sequence homology with Mad2, the mitotic checkpoint protein. Previously, we demonstrated the involvement of Mad2B in the cisplatin-induced DNA damage response. In this study, we extend our findings to show that Mad2B is recruited to sites of DNA damage in human cancer cells in response to cisplatin treatment. We found that in undamaged cells, Mad2B exists in a complex with Polζ-Rev1 and the APC/C subunit Cdc27. Following cisplatin-induced DNA damage, we observed an increase in the recruitment of Mad2B and Cdc20 (the activators of the APC/C), to the complex. The involvement of Mad2B-Cdc20-APC/C during DNA damage has not been reported before and suggests that the APC/C is activated following cisplatin-induced DNA damage. Using an in vitro ubiquitination assay, our data confirmed Mad2B-dependent activation of APC/C in cisplatin-treated cells. Mad2B may act as an accelerator for APC/C activation during DNA damage response. Our data strongly suggest a role for Mad2B-APC/C-Cdc20 in the ubiquitination of proteins involved in the DNA damage response.

• BMB Reports
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• 제39권2호
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• pp.197-207
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• 2006

Cajanus indicus is a herb with medicinal properties and is traditionally used to treat various forms of liver disorders. Present study aimed to evaluate the effect of a 43 kD protein isolated from the leaves of this herb against chloroform induced hepatotoxicity. Male albino mice were intraperitoneally treated with 2mg/kg body weight of the protein for 5 days followed by oral application of chloroform (0.75ml/kg body weight) for 2 days. Different biochemical parameters related to physiology and pathophysiology of liver, such as, serum glutamate pyruvate transaminase and alkaline phosphatase were determined in the murine sera under various experimental conditions. Direct antioxidant role of the protein was also determined from its reaction with Diphenyl picryl hydraxyl radical, superoxide radical and hydrogen peroxide. To find out the mode of action of this protein against chloroform induced liver damage, levels of antioxidant enzymes catalase, superoxide dismutase and glutathione-S-transferase were measured from liver homogenates. Peroxidation of membrane lipids both in vivo and in vitro were also measured as malonaldialdehyde. Finally, histopathological analyses were done from liver sections of control, toxin treated and protein pre- and post-treated (along with the toxin) mice. Levels of serum glutamate pyruvate transaminase and alkaline phosphatase, which showed an elevation in chloroform induced hepatic damage, were brought down near to the normal levels with the protein pretreatment. On the contrary, the levels of anti-oxidant enzymes such as catalase, superoxide dismutase and glutathione-S-transferase that had gone down in mice orally fed with chloroform were significantly elevated in protein pretreated ones. Besides, chloroform induced lipid peroxidation was effectively reduced by protein treatment both in vivo and in vitro. In cell free system the protein effectively quenched diphenyl picryl hydrazyl radical and superoxide radical, though it could not catalyse the breakdown of hydrogen peroxide. Post treatment with the protein for 3 days after 2 days of chloroform administration showed similar results. Histopathological studies indicated that chloroform induced extensive tissue damage was less severe in the mice livers treated with the 43 kD protein prior and post to the toxin administration. Results from all these data suggest that the protein possesses both preventive and curative role against chloroform induced hepatotoxicity and probably acts by an anti-oxidative defense mechanism.