• Animal cells and systems
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• v.8 no.1
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• pp.49-55
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• 2004

In vertebrates, multisubunit cofactors regulate gene expression through interacting with cell-type- and gene-specific DNA-binding proteins in a chromatin-selective manner. ADD1/SREBP1c regulates fatty acid metabolism and insulin-dependent gene expression through binding to SRE and E-box motif with dual DNA binding specificity. Although its transcriptional and post-translational regulation has been extensively studied, its regulation by interacting proteins is not well understood. To identify cellular proteins that associate with nuclear form of ADD1/SEBP1c, we employed the GST pull-down system with Hela cell nuclei extract. In this study, we demonstrated that Ku proteins interact specifically with ADD1/SREP1c protein. GST pull-down combined with peptide sequencing analysis revealed that Ku80 binds to ADD1/SREBP1c in vitro. Additionally, western blot analysis showed that Ku70, a heterodimerizing partner of Ku80, also associates with ADD1/SREBP1c. Furthermore, co-transfection of Ku70/Ku80 with ADD1/SREBP1c enhanced the transcriptional activity of ADD1/SREBP1c. Taken together, these results suggest that the Ku proteins might be involved in the lipogenic and/or adipogenic gene expression through interacting with ADD1/SREBP1c.

• Journal of Veterinary Clinics
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• v.21 no.3
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• pp.253-258
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• 2004

DNA double-strand break (DSB) is a serious treat for the cells including mutations, chromosome rearrangements, and even cell death if not repaired or misrepaired. Ku heterodimer regulatory DNA binding subunits (Ku70/Ku80) bound to double strand DNA breaks are able to interact with 470-kDa DNA-dependent protein kinase catalytic subunit (DNA-PKcs), and the interaction is essential for DNA-dependent protein kinase (DNA-PK) activity. The Ku80 mutants were designed to bind Ku70 but not DNA end binding activity and the peptides were treated in breast cancer cells for co-therapy strategy to see whether the targeted inhibition of DNA-dependent protein kinase (DNA-PK) activity sensitized breast cancer cells to ionizing irradiation or chemotherapy drug to develop a treatment of breast tumors by targeting proteins involved in damage-signaling pathway and/or DNA repair. We designed domains of Ku80 mutants, 26 residues of amino acids (HN-26) as a control peptide or 38 (HNI-38) residues of amino acids which contain domains of the membrane-translocation hydrophobic signal sequence and the nuclear localization sequence, but HNI-38 has additional twelve residues of peptide inhibitor region. We observed that the synthesized peptide (HNI-38) prevented DNA-PKcs from binding to Ku70/Ku80, resulting in inactivation of DNA-PK complex activity in breast cancer cells (MDA-465 and MDA-468). Consequently, the peptide treated cells exhibited poor to no DNA repair, and became highly sensitive to irradiation or chemotherapy drugs. The growth of breast cancer cells was also inhibited. These results demonstrate the possibility of synthetic peptide to apply breast cancer therapy to induce apoptosis of cancer cells.

• Radiation Oncology Journal
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• v.22 no.3
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• pp.208-216
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• 2004

Purpose: DNA-dependent protein kinase (DNA-PK) is a serine/threonine kinase consisting of a 470 kDa catalytic subunit (DNA-PKcs) and a heterodimeric regulatory complex, called Ku, which is composed of 70 kDa(Ku 70) and 86 kDa (Ku 80) proteins. The DNA-PK has been shown to play a pivotal role in rejoining DNA double-strand-breaks (dsb) in mammalian cells. The purpose of this study is to examine the relationship between the level of Ku expression and radiation sensitivity. Methods and Materials: Nine head and neck, cancer cell lines showed various intrinsic radiation sensitivities. Among the nine, AMC-HN-3 cell was the most sensitive for X-ray irradiation and AMC-HN-9 cell was the most resistance. The most sensitive and resistant cell lines were selected and the test sensitivity of radiation and expression of Ku were measured. Radiation sensitivity was obtained by colony forming assay and Ku protein expression using Western blot analysis. Results: Ku80 increased expression by radiation, wheres Ku70 did not. Overexpression of Ku80 protein increased radiation resistance in AMC-HN9 cell line. There was a correlation between Ku8O expression and radiation resistance. Ku80 was shown to play an important role in radiation damage response. Conclusion: Induction of Ku80 expression had an important role in DNA damage repair by radiation. Ku80 expression may be an effective predictive assay of radiosensitivity on head and neck cancer.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.2
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• pp.795-799
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• 2013

Ku70/80 heterodimer is a central element in the nonhomologous end joining (NHEJ) DNA repair pathway, Ku80 playing a key role in regulating the multiple functions of Ku proteins. It has been found that the Ku80 protein located at telomeres is a major contributor to radiosensitivity in some telomerase positive human cancer cells. However, in ALT human osteosarcoma cells, the precise function in radiosensitivity and telomere maintenance is still unknown. The aim of this study was to investigate the effects of Ku80 depletion in the U2OS ALT cell line cell line. Suppression of Ku80 expression was performed using a vector-based shRNA and stable Ku80 knockdown in cells was verified by Western blotting. U2OS cells treated with shRNA-Ku80 showed lower radiobiological parameters (D0, Dq and SF2) in clonogenic assays. Furthermore, shRNA-Ku80 vector transfected cells displayed shortening of the telomere length and showed less expression of TRF2 protein. These results demonstrated that down-regulation of Ku80 can sensitize ALT cells U2OS to radiation, and this radiosensitization is related to telomere length shortening.

• Journal of Life Science
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• v.15 no.3 s.70
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• pp.406-414
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• 2005

The genetic instability of cancer cells may be related to inappropriately activated DNA repair pathways. In present study, the modulated expression of DNA-dependent protein kinase (DNA-PK), a major DNA repair protein, in human cancer metastatic cells was tested. The expressions of Ku70/80, regulatory subunit of DNA-PK, and the Ku DNA-binding activity in various highly metastatic cell lines were higher than those in each parental cell line. Also, the expression of DNA-PKcs, catalytic subunit of DNA-PK, and the kinase activity of the whole DNA-PK complex in highly metastatic cells were significantly increased as compared to those of parental cells, suggesting that the enhanced DNA repair capacity of metastatic cells could be associated with aberrant use of DNA repair, which may mediate tumor progression and metastatic potential. Increased EGFR (epidermal growth factor receptor) signaling has been associated with tumor invasion and metastasis, and the linkage between EGFR-mediated signaling and DNA-PK has been suggested. This study showed that PKI166, the new EGFR tyrosine kinase inhibitor, modulated the expressions of Ku70/80 and DNA-PKcs and also revealed the chemosensitization effect of PKI166 against metastatic cells may be in part due to inhibition of Ku70/80. These results suggest that interference in EGFR signaling by EGFR inhibitor resulted in the impairment of DNA repair activity, and thus DNA-PK could be possible molecular targets for therapy against metastatic cancer cells.

• The Korean Journal of Physiology and Pharmacology
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• v.7 no.1
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• pp.9-14
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• 2003

Recent studies indicated that cancer cells become resistant to ionizing radiation (IR) and chemotherapy drugs by enhanced DNA repair of the lesions. Therefore, it is expected to increase the killing of cancer cells and reduce drug resistance by inhibiting DNA repair pathways that tumor cells rely on to escape chemotherapy. There are a number of key human DNA repair pathways which depend on multimeric polypeptide activities. For example, Ku heterodimer regulatory DNA binding subunits (Ku70/Ku80) on binding to double strand DNA breaks (DSBs) are able to interact with 470-kDa DNA-dependent protein kinase catalytic subunit (DNA-PKcs), and are essential for DNA-dependent protein kinase (DNA-PK) activity. It has been known that DNA-PK is an important factor for DNA repair and also is a sensor-transmitting damage signal to downstream targets, leading to cell cycles arrest. Our ultimate goal is to develop a treatment of breast tumors by targeting proteins involved in damage-signaling pathway and/or DNA repair. This would greatly facilitate tumor cell cytotoxic activity and programmed cell death through DNA damaging drug treatment. Therefore, we designed a domain of Ku80 mutants that binds to Ku70 but not DNA end binding activity and used the peptide in co-therapy strategy to see whether the targeted inhibition of DNA-PK activity sensitized breast cancer cells to irradiation or chemotherapy drug. We observed that the synthesized peptide (HNI-38) prevented DNA-PKcs from binding to Ku70/Ku80, thus resulting in inactivation of DNA-PK activity. Consequently, the peptide treated cells exhibited poor to no DNA repair, and became highly sensitive to IR or chemotherapy drugs, and the growth of breast cancer cells was inhibited. Additionally, the results obtained in the present study also support the physiological role of resistance of cancer cells to IR or chemotherapy.

• Membrane Journal
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• v.6 no.4
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• pp.284-288
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• 1996

The crosslinked PVA/PAA membranes developed in our laboratory have been characterized for water-isopropyl alcohol mixture in terms of permeabilities and separation factor. When the feed mixture was 12wt% water, the permeability and the separation factor for PVA/PAA=75/25 membrane show $63g/m^{2}h$ and 1520 at $80^{\circ}C$, respectively. In case of 5wt% water in feed mixture, the permeability for PVA/PAA=75/25 membrane is $56g/m^{2}h$ at 8$0^{\circ}C$ while the separation factor is 1563.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.2
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• pp.683-687
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• 2012

Ku70 plays an important role in DNA double-strand break repair. Studies revealing conflicting results on the role of the Ku70-1310C/G promoter polymorphism on cancer risk led us to perform a meta-analysis to investigate this relationship. Ten case-control studies with 2566 cases and 3058 controls were identified. Odds ratios (ORs) and 95% confidence intervals (CIs) were used to assess the strength of associations. The overall results suggested no association between the Ku70-1310C/G promoter polymorphism and total cancer risk. However, on stratified analysis, significantly increased risks were observed among the Asian population (GG vs. CC: OR=1.50, 95%CI=1.10-2.06; GG vs. CC/CG: OR=1.47, 95%CI=1.07-2.01) and population-based case-control studies (GG vs. CC: OR=1.57, 95%CI=1.12-2.22; CG vs. CC: OR=1.35, 95%CI=1.11-1.64; CG/GG vs. CC: OR=1.37, 95%CI=1.14-1.65). Additionally, variant genotypes were associated with a significantly increased breast cancer risk (GG vs. CC: OR=1.80, 95%CI=1.26-2.56; GG vs. CC/CG: OR=1.40, 95%CI=1.01-1.95).

• Journal of the Ergonomics Society of Korea
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• v.33 no.6
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• pp.553-563
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• 2014

Objective: The purpose of this study was to evaluate the effect of gender (male, female) and grip spans (45, 50, 60, 70, 80mm) on total grip strength, resultant force, finger force and subjective discomfort rating. Background: In order to prevent musculoskeletal disorders, studies of hand tools need to be preceded based on grip strength, finger force, and subjective discomfort rating. However, experimental apparatus using tools such as pliers that reflect the actual work place was almost non-existent. Method: Fifty-Two (26 males and 26 females) participants were recruited from the student population. In this study, a pair of revised pliers, which can change grip span from 45 to 80mm was applied to estimate total grip strength, resultant force and individual finger forces. All participants were asked to exert a maximum grip force with three repetitions, and to report the subjective discomfort rating for five grip spans of pliers (45, 50, 60, 70, 80mm). Results: There were significant differences of total grip strength, resultant force, individual finger forces and subjective discomfort rating according to grip span. The lowest total grip strength was obtained from the grip span of 80mm for both genders. For resultant force, the highest resultant force was exerted at grip spans of 50, 60 and 70mm for females and 50 and 60mm for males. The lowest subjective discomfort rating was observed in the 50mm for both genders. Conclusion: Based on the result, 50mm and 60mm grip spans which provide the highest force and lowest discomfort rating might be recommendable for the male and female pliers users. Application: The findings of this study can provide guidelines on designing a hand tool to help to reduce hand-related musculoskeletal disorders and obtain better performance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.10
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• pp.1973-1981
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• 1994

A PLDRO(Phase Locked Dielectric Resonator Oscillator) in Ku-band(10.95-11.70GHz) is designed with the concept of the feedback property of PLL(Phase Locked Loop). A series feedback type DRO is developed, and VCDRO(Voltage Controlled Dielectric Resonator Oscillator) using a varactor diode as a voltage-variable capacitor is implemented to tune oscillating frequency electrically. Then, PLDRO is designed by using a SPD(Sampling Phase Detector). This PLDRO is phase-locked voltage controlled DRO to reference source(VHF band) by SPD at 10.00 GHz for European FSS(Fixed Satellite Service). The PLDRO generates output power greater than 10dBm at 10.00 GHz and has phase noise of -80 dBc/Hz at 10 KHz offset from carrier. This PLDRO achieves much better frequency stability than conventional VCDRO.