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Oral, North Korea

Yang H.-Y.,Chonbuk National University | Kim J.,Chonbuk National University | Lee K.-Y.,Institute of Oral Bioscience | Jang Y.-S.,Chonbuk National University
Molecular Immunology | Year: 2010

In addition to their essential role in antigen presentation, MHC class II molecules have been widely described as receptors associated with signal transduction involved in regulating B cell function. However, their precise function and mechanism in signal transduction are not yet fully elucidated. Our previous studies demonstrated that cross-linking of MHC class II molecules led to the inhibition of resting B cell activation in which various signal molecules were involved. Especially, Rac-associated ROS-dependent MAP kinases, including ERK1/2 and p38, are involved in MHC class II-associated negative signal transduction in the phorbol 12, 13-dibutyrate (PDBU)-treated, but not LPS-treated, resting B cell line, 38B9. In this study, we further illustrated that PKC regulates downstream signal molecules, including MAP kinases and NF-κB in PDBU-stimulated resting B cells, together with Rac and ROS. In addition, we found that phosphatidylinositol 3-kinase (PI3K)-dependent activation of ERK/p38 MAP kinases was associated with the signaling procedure in PDBU-induced B cell activation. Collectively, Rac/ROS-related PKC and PI3K signaling are involved in a negative regulation cascade through the cross-linking of MHC class II molecules by anti-MHC class II antibodies in resting B cells. © 2010 Elsevier Ltd. All rights reserved. Source


Kim J.-S.,Institute of Oral Bioscience | Kim J.-S.,Chonbuk National University | Yi H.-K.,Institute of Oral Bioscience
Experimental Gerontology | Year: 2015

Aging is characterized by the progressive decline in mass and function of the skeletal muscle along with increased susceptibility to inflammation, oxidative stress, and atrophy. In this study, we investigate the effect of intermittent bout and single bout exercise training on inflammatory molecules in young (3 months) and old (22 months) male Sprague-Dawley rats. The rats were divided into 6 groups. Young and old rats were randomly assigned for control and two exercise training groups, single bout (S type): 30 min/day, 5 days/week for 6. weeks and intermittent bout (I type): three times for 10 min/day, 5 days/week for 6 weeks respectively. The exercise training was carried out by a treadmill at a speed of 15. m/min (young) or 10 m/min (old) with a slope of 5°. After 48. h of the final exercise bout, muscle samples were collected for biochemical assay. I type exercise training reduced the serum levels of inflammatory molecules such as interleukin-1β (IL-1β), tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and malondialdehyde (MDA) in old rats. By contrast, interleukin-4 (IL-4) and superoxide dismutase (SOD) were elevated. Consequently in skeletal muscles, inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) were decreased significantly in the old group of I type. However, the matrix metalloproteinase-2 (MMP-2) level had no positive effects. Also, phosphorylation of mammalian target of rapamycin (p-mTOR) and myogenic differentiation (MyoD) were increased markedly in S and I types of old rats. These results suggest that I type exercise training appears more effective to reduce age-associated inflammatory molecules, and may recommend in regulating against chronic complicated disease induced by aging. © 2015 Elsevier Inc. Source


Bhattarai J.P.,Institute of Oral Bioscience | Roa J.,University of Otago | Herbison A.E.,University of Otago | Han S.K.,Institute of Oral Bioscience
Endocrinology | Year: 2014

The effect of serotonin (5-HT) on the electrical excitability of GnRH neurons was examined using gramicidin perforated-patch electrophysiology in transgenic GnRH-green fluorescent protein mice. In diestrous female, the predominant effect of 5-HT was inhibition (70%) with 50% of these cells also exhibiting a late-onset excitation. Responses were dose dependent (EC 50 = 1.2μM) and persisted in the presence of amino acid receptor antagonists and tetrodotoxin, indicating a predominant postsynaptic action of 5-HT. Studies in neonatal, juvenile, peripubertal, and adult mice revealed that 5-HT exerted less potent responses fromGnRHneurons with advancing postnatal age in both sexes. In adult male mice, 5-HT exerted less potent hyperpolarizing responses with more excitations compared with females. In addition, adult proestrous female GnRH neurons exhibited reduced inhibition and a complete absence of biphasic hyperpolarization-excitation responses. Studies using 5-HT receptor antagonists demonstrated that the activation of 5-HT1A receptors mediated the inhibitory responses, whereas the excitation was mediated by the activation of 5-HT2A receptors. The 5-HT-mediated hyperpolarization involved both potassium channels and adenylate cyclase activation, whereas the 5-HT excitation was dependent on protein kinase C. The effects of exogenous 5-HT were replicated using fluoxetine, which enhances endogenous 5-HT levels. These studies demonstrate that 5-HT exerts a biphasic action on most GnRH neurons whereby a fast 5HT1A-mediated inhibition occurs alongside a slow 5-HT2A excitation. The balance of 5-HT-evoked inhibition vs excitation is developmentally regulated, sexually differentiated, and variable across the estrous cycle and may play a role in regulation of hypothalamic-pituitarygonadal axis throughout postnatal development. Copyright © 2014 by the Endocrine Society. Source


Lee R.,Institute of Oral Bioscience | Shin J.-C.,Pohang Center for Evaluation of Biomaterials | Kim K.-H.,Mokpo National University | Choi Y.-H.,Korea University | And 2 more authors.
Oncology Reports | Year: 2015

7,8-Dihydroxyflavone (7,8-DHF) is a member of the flavonoid family and has recently been identified as a brain-derived neurotrophic factor mimetic that selectively activates tropomyosin-receptor kinase B with high affinity. The antioxidant and anticancer effects of 7,8-DHF have been reported. However, the pharmacological mechanisms of 7,8-DHF in oral cancer are unclear. Thus, we investigated the mechanisms of the antiproliferative action of 7,8-DHF on HN22 and HSC4 oral squamous cell carcinoma cell lines. We demonstrated that 7,8-DHF decreased cell growth and induced apoptosis in the HN22 and HSC4 cells through regulation of specificity protein 1 (Sp1) using the MTS assay, DAPI staining, Annexin V, propidium iodide staining, reverse transcriptionpolymerase chain reaction, immunocytochemistry, pull-down assay and western blot analysis. The results showed that the Sp1 protein bound with 7,8-DHF in the HN22 and HSC4 cells. Taken together, the results suggest that 7,8-DHF could modulate Sp1 transactivation and induce apoptotic cell death by regulating the cell cycle and suppressing antiapoptotic proteins. Furthermore, 7,8-DHF may be valuable for cancer prevention and better clinical outcomes. Source


Kim J.-S.,Institute of Oral Bioscience | Kim J.-S.,Chonbuk National University | Lee Y.-H.,Institute of Oral Bioscience | Choi D.-Y.,Chonbuk National University | Yi H.-K.,Institute of Oral Bioscience
Journal of Sports Science and Medicine | Year: 2015

The skeletal muscle in aged rats adapts rapidly following a period of exercise. This adaptation includes structural remodeling and biochemical changes such as an up-regulation of antioxidant enzymes, content of stress and heat shock proteins (HSPs). However, the associated molecular mechanisms mediating different types of exercise training-induced adaptations are not yet completely understood. Therefore, the purpose of this study was to investigate the effects of duration and frequency exercise on the expression of HSPs, antioxidant enzymes, and mitogenactivated protein kinase (MAPKs) in the skeletal muscles of aged rats. Young (3-month-old) and aged (20-month-old) male Sprague-Dawley rats were randomly assigned to 6 groups and extensor digitorum longus (EDL; fast twitch muscle fiber) and soleus (SOL; slow twitch muscle fiber) skeletal muscles were collected immediately. The expression pattern of HSPs in skeletal muscles was decreased in old groups compared with young groups. Especially, HSPs showed lower expression in SOL than EDL muscle. Interestingly, HSPs in aged rats was increased significantly after S1 (single long-duration; 1×30 min, 5 days/week for 6 weeks) and M1 types (multiple short-duration; 3×10 min·day -1, 5 days·week-1 for 6 weeks) than S2 (single longduration; 1×30 min, 3 days/week for 6 weeks) and M2 (multiple short-duration; 3×10 min·day -1, 3 days·week-1 for 6 weeks) types of exercise training. Also, superoxide dismutase (SODs) showed similar expression as HSP did. On the contrary, the p-ERK and p-JNK were down regulated. In addition, p-p38 level in the SOL muscle was activated markedly in all exercise groups. These results demonstrate that increasing of HSP expression through duration and frequency exercise can lead to protection and training-induced adaptation against aging-induced structural weakness in skeletal muscles. © 2015, Journal of Sports Science and Medicine. All rights reserved. Source

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