• Journal of Physiology & Pathology in Korean Medicine
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• v.27 no.6
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• pp.764-770
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• 2013

Stevia rebaudiana is a traditional herb used as a sweetener in Brazil and Paraguay as well as Korea and China. This study investigated the efficacy of Stevia rebaudiana methanol extract (SRE) to protect cells against the mitochondrial dysfunction and apoptosis in hepatocyte. To determine the effects of SRE on oxidative stress, we used the human derived hepatocyte cell line, HepG2 cell. Treatment of arachidonic acid (AA)+iron in HepG2 cells synergistically amplified cytotoxicity, as indicated by the excess reactive oxygen species (ROS) and mitochondrial permeability transition by fluorescence activated cell sorter (FACS) and immunoblot analysis. Treatment with SRE protected hepatocytes from AA+iron-induced cellular toxicity, as shown by alterations in the protein levels related with cell viability such as procaspase-3. SRE also prevented the mitochondrial dysfunction induced by AA+iron, and showed anti-oxidant effects as inhibition of $H_2O_2$ production and GSH depletion. Moreover, we measured the effects of SRE on AMP-activated protein kinase (AMPK), a key regulator in determining cell survival or death. Acetyl-CoA Carboxylase (ACC), a direct downstream target of AMPK. SRE increased phosphorylation of ACC, and prevented the inhibition of ACC phosphorylation by AA+iron. These results indicated that SRE has the ability to protect cells against AA+iron-induced $H_2O_2$ production and mitochondrial impairment, which may be mediated with AMPK-ACC pathway.

• Bulletin of the Korean Chemical Society
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• v.35 no.8
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• pp.2494-2504
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• 2014

P38 mitogen activated protein (MAP) kinase is an important anti-inflammatory drug target, which can be activated by responding to various stimuli such as stress and immune response. Based on the conformation of the conserved DFG loop (in or out), binding inhibitors are termed as type-I and II. Type-I inhibitors are ATP competitive, whereas type-II inhibitors bind in DFG-out conformation of allosteric pocket. It remains unclear that how these allosteric inhibitors stabilize the DFG-out conformation and interact. Organosilicon compounds provide unusual opportunity to enhance potency and diversity of drug molecules due to their low toxicity. However, very few examples have been reported to utilize this property. In this regard, we performed docking of an inhibitor (BIRB) and its silicon analog (Si-BIRB) in an allosteric binding pocket of p38. Further, molecular dynamics (MD) simulations were performed to study the dynamic behavior of the simulated complexes. The difference in the biological activity and mechanism of action of the simulated inhibitors could be explained based on the molecular mechanics/generalized Born surface area (MM/GBSA) binding free energy per residue decomposition. MM/GBSA showed that biological activities were related with calculated binding free energy of inhibitors. Analyses of the per-residue decomposed energy indicated that van der Waals and non-polar interactions were predominant in the ligand-protein interactions. Further, crucial residues identified for hydrogen bond, salt bridge and hydrophobic interactions were Tyr35, Lys53, Glu71, Leu74, Leu75, Ile84, Met109, Leu167, Asp168 and Phe169. Our results indicate that stronger hydrophobic interaction of Si-BIRB with the binding site residues could be responsible for its greater binding affinity compared with BIRB.

• Journal of Veterinary Science
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• v.23 no.5
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• pp.72.1-72.14
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• 2022

Background: The treatment of acute kidney injury (AKI), a common disease in dogs, is limited. Therefore, an effective method to prevent AKI in veterinary clinics is particularly crucial. Objectives: Hydrogen sulfide (H₂S) is the third gaseous signal molecule involved in various physiological functions of the body. The present study investigated the effect of H₂S on cisplatin-induced AKI and the involved mechanisms in dogs. Methods: Cisplatin-injected dogs developed AKI symptoms as indicated by renal dysfunction and pathological changes. In the H₂S-treated group, 50 mM sodium hydrosulfide (NaHS) solution was injected at 1 mg/kg/h for 30 min before cisplatin injection. After 72 h, tissue and blood samples were collected immediately. We performed biochemical tests, optical microscopy studies, analysis with test kits, quantitative reverse-transcription polymerase chain reaction, and western blot analysis. Results: The study results demonstrated that cisplatin injection increased necroptosis and regulated the corresponding protein expression of receptor interacting protein kinase (RIPK) 1, RIPK3, and poly ADP-ribose polymerase 1; furthermore, it activated the expressions of inflammatory factors, including tumor necrosis factor-alpha, nuclear factor kappa B, and interleukin-1β, in canine kidney tissues. Moreover, cisplatin triggered oxidative stress and affected energy metabolism. Conversely, an injection of NaHS solution considerably reduced the aforementioned changes. Conclusions: In conclusion, H₂S protects the kidney from cisplatin-induced AKI through the mitigation of necroptosis and inflammation. These findings provide new and valuable clues for the treatment of canine AKI and are of great significance for AKI prevention in veterinary clinics.

• Asian-Australasian Journal of Animal Sciences
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• v.32 no.8
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• pp.1112-1121
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• 2019

Objective: Gram-negative bacteria lipopolysaccharide (LPS) has been reported to be associated with uterine impairment, embryonic resorption, ovarian dysfunction, and follicle retardation. Here, we aimed to investigate the toxic effects of LPS on the maturation ability and parthenogenetic developmental competence of bovine oocytes. Methods: First, we developed an in vitro model to study the response of bovine cumulusoocyte complexes (COCs) to LPS stress. After incubating germinal vesicle COCs in $10{\mu}g/mL$ of LPS, we analyzed the following three aspects: the expression levels of the LPS receptor toll-like receptor 4 (TLR4) in COCs, activities of intracellular signaling protein p38 mitogen-activated protein kinase (p38 MAPK) and nuclear factor-kappa B (NF-${\kappa}B$); and the concentrations of interleukin (IL)-$1{\beta}$, tumor necrosis factor (TNF)-${\alpha}$, and IL-6. Furthermore, we determined the effects of LPS on the maturation ability and parthenogenetic developmental competence of bovine oocytes. Results: The results revealed that LPS treatment significantly elevated TLR4 mRNA and protein expression levels in COCs. Exposure of COCs to LPS also resulted in a marked increase in activity of the intracellular signaling protein p-p38 MAPK and NF-${\kappa}B$. Furthermore, oocytes cultured in maturation medium containing LPS had significantly higher concentrations of the proinflammatory cytokines IL-$1{\beta}$, TNF-${\alpha}$, and IL-6. LPS exposure significantly decreased the first polar body extrusion rate. The cytoplasmic maturation, characterized by polar body extrusion and distribution of peripheral cortical granules, was significantly impaired in LPS-treated oocytes. Moreover, LPS exposure significantly increased intracellular reactive oxygen species levels and the relative mRNA abundance of the antioxidants thioredoxin (Trx), Trx2, and peroxiredoxin 1 in oocytes. Moreover, the early apoptotic rate and the release of cytochrome C were significantly increased in response to LPS. The cleavage, morula, and blastocyst formation rates were significantly lower in parthenogenetically activated oocytes exposed to LPS, while the incidence of apoptotic nuclei in blastocysts was significantly increased. Conclusion: Together, these results provide an underlying mechanism by which LPS impairs maturation potential in bovine oocytes.

• Molecules and Cells
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• v.40 no.3
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• pp.230-242
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• 2017

In the Arabidopsis genome, approximately 80 MAP3Ks (mitogen-activated protein kinase kinase kinases) have been identified. However, only a few of them have been characterized, and the functions of most MAP3Ks are largely unknown. In this paper, we report the function of MAP3K16 and several other MAP3Ks, MAP3K14/15/17/18, whose expression is salt-inducible. We prepared MAP3K16 overexpression (OX) lines and analyzed their phenotypes. The result showed that the transgenic plants were ABA-insensitive during seed germination and cotyledon greening stage but their root growth was ABA-hypersensitive. The OX lines were more susceptible to water-deficit condition at later growth stage in soil. A MAP3K16 knockout (KO) line, on the other hand, exhibited opposite phenotypes. In similar transgenic analyses, we found that MAP3K14/15/17/18 OX and KO lines displayed similar phenotypes to those of MA3K16, suggesting the functional redundancy among them. MAP3K16 possesses in vitro kinase activity, and we carried out two-hybrid analyses to identify MAP3K16 substrates. Our results indicate that MAP3K16 interacts with MKK3 and the negative regulator of ABA response, ABR1, in yeast. Furthermore, MAP3K16 recombinant protein could phosphorylate MKK3 and ABR1, suggesting that they might be MAP3K16 substrates. Collectively, our results demonstrate that MAP3K16 and MAP3K14/15/17/18 are involved in ABA response, playing negative or positive roles depending on developmental stage and that MAP3K16 may function via MKK3 and ABR1.

• Journal of Nutrition and Health
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• v.54 no.3
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• pp.321-333
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• 2021

Purpose: Reflux esophagitis is a disease caused by the reflux of stomach contents and stomach acid etc. into the esophagus due to defect in the lower esophageal sphincter and is currently increasing worldwide. This study was conducted to evaluate the effect of a mixture of Citrus Reticulata and Scutellariae Radix (CS) extract on acute reflux esophagitis in rats. Methods: Rats were divided into five groups for examination: normal group (Normal, n = 8), water-treated acute reflux esophagitis rats (Control, n = 8), tocopherol 30 mg/kg body weight-treated acute reflux esophagitis rats (Toco, n = 8), CS 100 mg/kg body weight-treated acute reflux esophagitis rats (CS100, n = 8), CS 200 mg/kg body weight-treated acute reflux esophagitis rats (CS200, n = 8). The experimental groups were administrated of each treatment compounds and after 90 min, acute reflux esophagitis was induced through surgery. Rats were sacrificed 5 h after surgery. We measured the level of reactive oxygen species (ROS) in serum and analyzed the expression of nicotinamide adenine dinucleotide phosphate, inflammatory, and tight junction-related proteins by western blot in the esophageal tissues. Results: CS administration significantly protected the esophageal mucosal damage due to reflux esophagitis, and the level of ROS in the serum was significantly reduced with CS administration as compared to Control. In addition, CS administration significantly suppressed mitogen-activated protein kinase (MAPK or MAP kinase) and nuclear factor-kappa B (NF-κB) pathways and increased protein expressions of tight junction protein. Conclusion: These results suggest that the CS not only regulates the expression of inflammatory proteins by inhibiting oxidative stress, but also reduces damage to the esophageal mucosa by inhibiting the expression of tight junction proteins.

• Journal of Photoscience
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• v.9 no.2
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• pp.229-232
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• 2002

There are two distinct UV-responsive signaling pathways in UV-irradiated mammalian cells, i.e., the DNA damage-dependent and -independent pathways. The former occurs in nucleus and results in growth arrest and apoptosis via post-translational modification of p53. The latter is initiated by oxidative stress and/or by damages in cell membrane or cytoplasm, which activate signaling cascade through intracellular molecules including mitogen activated protein kinases (MAPK). In normal human fibroblastic cells, all of MAPK family members, extracellular signal-related kinases (ERK), c-Jun N-terminal kinases (JNK) and p38, were rapidly phosphorylated following UV-irradiation. ERK phosphorylation was suppressed by an inhibitor of receptor tyrosine kinases (RTK). As ERK usually responds to mitogenic stimuli from RTK ligands, UV-induced ERK phosphorylation may be linked to the proliferation of survived cells. In contrast, phosphorylation of JNK and p38, as well as apoptosis, were modulated by the level of UV-generated oxidative stress Therefore, JNK and p38 may take part in oxidative stress-mediated apoptosis. Phosphorylation of p53 at Ser and Thr residues are essential for stabilization and activation of p53. Among several sites reported, we confirmed phosphorylation at Ser-15 and Ser-392 after UV-irradiation. Both of these were inhibited by a phosphoinositide 3-kinase inhibitor, presumably due to the shutdown of signals from DNA damage to p53. Phosphorylation at Ser-392 was also sensitive to an antioxidant and a p38 inhibitor, suggesting that Ser-392 of p53 is one of the possible points where DNA damage-dependent and -independent apoptic signals merge. Thus, MAPK pathway links UV-induced intracellular signals to the nuclear responses and modifies DNA damage-dependent cellular outcome, resulting in the determination of cell death.

• Nutrition Research and Practice
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• v.14 no.1
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• pp.3-11
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• 2020

BACKGROUND/OBJECTIVES: Oxidative stress causes cell damage and death, which contribute to the pathogenesis of neurodegenerative diseases. Urolithin A (UA), a gut microbial-derived metabolite of ellagitannins and ellagic acid, has high bioavailability and various health benefits such as antioxidant and anti-inflammatory effects. However, it is unknown whether it has protective effects against oxidative stress-induced cell death. We investigated whether UA ameliorates H₂O₂-induced neuronal cell death. MATERIALS/METHODS: We induced oxidative damage with 300 μM H₂O₂ after UA pretreatment at concentrations of 1.25, 2.5, and 5 μM in SK-N-MC cells. Cytotoxicity and cell viability were determined using the CCK-8 assay. The formation of reactive oxygen species (ROS) was measured using a 2,7-dichlorofluorescein diacetate assay. Hoechst 33342 staining was used to characterize morphological changes in apoptotic cells. The expressions of apoptosis proteins were measured using Western blotting. RESULTS: UA significantly increased cell viability and decreased intracellular ROS production in a dose-dependent manner in SK-N-MC cells. It also decreased the Bax/Bcl-2 ratio and the expressions of cytochrome c, cleaved caspase-9, cleaved caspase-3, and cleaved PARP. In addition, it suppressed the phosphorylation of the p38 mitogen-activated protein kinase (MAPK) pathway. CONCLUSIONS: UA attenuates oxidative stress-induced apoptosis via inhibiting the mitochondrial-related apoptosis pathway and modulating the p38 MAPK pathway, suggesting that it may be an effective neuroprotective agent.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.31 no.4 s.54
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• pp.311-321
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• 2005

Tea (Camellia sinenis) is a popular beverage consumed worldwide. Since green tea, mainly consumed in Asia, has various biological activities, green tea components became one of the most favorite candidates as a functional materials for cosmetics and functional foods. The biological activities of green tea for skin cue have been ranged from protection of epidermal cells to the stimulation of extracellular matrix (ECM) biosynthesis. Green tea polyphenols (GTPs), which are active ingredients of green tea, possess anti-inflammatory, anti-carcinogenic and immune potentiation properties as well as antioxidant. They also modulate intracellular signal transduction pathways. GTPs decrease ultraviolet (UV)-induced oxidative stress, thus suppress mitogen-activated protein kinase (MAPK) pathway and apoptosis in keratinocytes. In addition, GTPs prevent the Induction of inflammatory mediators, such as cyclooxygenase-2 (COX-2), interleukin-8 (IL-8), and vascular endothelial growth factor (VEGF) by tumor necrosis factor alpha $(TNF{\alpha})$ or chemical treatment in keratinocytes. GTPs treatment protects from chemical-or UV-induced skin tumor incidence in animal experiment. Besides, GTPs stimulate keratinocyte differentiation and proliferation of normal and aged epidermal cells, resectively, and suppress matrix metalloproteinases (MMPs) release. According to the progress of formulation study, green tea components will be guaranteed materials for the more effective skin cue products.

• The Korea Journal of Herbology
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• v.36 no.6
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• pp.39-46
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• 2021

Objectives : AMP-activated protein kinase (AMPK) is a key metabolic regulator that reduces lipogenesis. AMPK is mainly activated via phosphorylation of liver kinase B (LKB) 1 under energy stress. Here, we highlighted the anti-obesity effect and underlying mechanism of Coix lacryma-jobi var. mayuen Stapf sprout water extract (CSW) sprout extract in connection with the LKB1/AMPK signaling pathway. Methods : C57BL/6 mice (20~25 g) fed HFD to induce obesity and at the same time administered CSW 100 mg/kg (CSWL; (CSWL; CSW low concentration) or CSW 200 mg/kg (CSWH; CSW high concentration) or Garcinia extract (Garcinia) 200 mg/kg orally for 6 weeks. Body weight and food intake were measured at the same time each day. After 6 weeks of CSW administration, liver tissue and serum were obtained through an autopsy. After the end of the experiment, biochemical analysis (triglycerides (TG), total cholesterol (TC), HDL-cholesterol, and LDL-cholesterol) was performed on the serum. And then, protein levels related to TG and TC synthesis were measured through western blot analysis in liver tissue. Results : As a result, serum TG, TC, and LDL-cholesterol levels were significantly increased in the control group and significantly decreased in the CSW administration group. On the other hand, the HDL-cholesterol level was increased in the CSW-administered group. And as a result of Western blot analysis, CSW significantly increased the phosphorylation of LKB1 & AMPK, and remarkably decreased the expression of factors related to TG and TC synthesis. Conclusions : Our findings suggest that CSW influences the TG and TC synthesis to positively affect HFD-induced obesity in C57BL/6 mice.