• Biomolecules & Therapeutics
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• v.11 no.2
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• pp.112-118
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• 2003

1-Methylated $\beta$-carbolines (harmaline and harmalol) and antioxidants (N-acetylcysteine and ascorbate) reduced the loss of cell viability in differentiated PC 12 cells treated with 5 mM glutamate. $\beta$-Carbolines prevented the glutamate-induced decrease in mitochondrial membrane potential, cytochrome c release and caspase-3 activation in PC 12 cells. $\beta$-Carbolines reduced the formation of reactive oxygen species and depletion of glutathione due to glutamate in PC12 cells. $\beta$-Carbolines revealed a scavenging action on hydrogen peroxide and reduced the iron and EDTA-mediated degradation of 2-deoxy-D-ribose. The results suggest that I-methylated $\beta$-carbolines attenuate the cytotoxic effect of glutamate on PC12 cells by reducing the alteration of mitochondrial membrane permeability that seems to be mediated by oxidative stress.

• Proceedings of the Korean Society of Applied Pharmacology
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• 2008.04a
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• pp.23-30
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• 2008

Mitochondria biogenesis requires a coordination of two genomes, nuclear DNA (nDNA) and mitochondrial DNA (mtDNA). Disruption of mitochondria function leads to a loss of mitochondrial membrane potential and ATP generating capacity and consequently results in chronic degenerative diseases including insulin resistance, metabolic syndrome and neurodegenerative diseases. Although PPAR-${\gamma}$ coactivator-$1{\alpha}$ (PGC-$1{\alpha}$) was discovered as a central regulator of mitochondria biogenesis and a transcriptional co-activator of nuclear respiratory factor (NRF) and mitochondrial transcription factor A (Tfam), the expressions of PGC-$1{\alpha}$, NRF and Tfam were not significantly altered in tissues showing abnormal mitochondria functions. This observation suggests that there should be another regulator(s) for mitochondria function. Here, we demonstrate microRNAs (miRNAs) can modulate mitochondria function. Overexpression of microRNA dissipated mitochondrial membrane potential and increased ROS production in vitro and in vivo. It will be discussed the target of microRNA and its role in metabolic syndrome.

• The Korean Journal of Physiology and Pharmacology
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• v.9 no.4
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• pp.209-213
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• 2005

Interstitial cells of Cajal (ICCs) are the pacemaker cells that generate slow waves in the gastrointestinal (GI) tract. In the present study, we investigated the effect of mitochondrial ATP-sensitive potassium (mitoKATP) channel on pacemaking activity in cultured ICCs from murine small intestine by using whole-cell patch clamp techniques. Under current clamp mode, at 10μM glibenclamide, there was no change in pacemaking activity of ICCs. At $30{\mu}M$ glibenclamide, an inhibitor of the ATP sensitive $K^+$ channels, we could find two examples. If pacemaking activity of ICCs was irregulating, pacemaking activity of ICCs was changed into regulating and if in normal conditions, membrane potential amplitude was increased. At $50{\mu}M$ glibenclamide, the resting membrane potential was depolarized. At 3mM 5-HDA, an inhibitor of the mitoKATP channels, inhibited the pacemaking activity of ICCs. Both the amplitude and the frequency were decreased. At 5 mM 5-HDA, both the amplitude and the frequency were completely abolished. Diazoxide, an opener of the mitoKATP channels, was applied to examine its effect on pacemaking activity of ICCs. At $50{\mu}M$ concentration, the pacemaking activity of ICCs was inhibited. Both the amplitude and the frequency were decreased. At 1 mM concentration, both the amplitude and the frequency were completely abolished and the resting membrane potential was shaked.These results indicate that mitoKATP channel has an important role in pacemaking activity of ICCs.

• The Journal of Korean Obstetrics and Gynecology
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• v.19 no.1
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• pp.1-13
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• 2006

Purpose : Polygonum cuspidatum extract is an oriental herb which has been used for uterine diseases. In this study, the effects of Polygonum cuspidatum extract were investigated on inducing growth inhibition and apoptosis of human uterine cervical carcinoma cells. Methods : Viability of Polygonum cuspidatum extract-induced ME-180 cells was measured by MTT assay. Apoptotic cells were visualized by EtBr/AcOr staining under fluorescent microscope. Nucleosomal DNA fragmentation was assayed by agarose gel electrophoresis. Cell cycle distribution and changes in mitochondrial membrane potential were observed by flow cytometry. Results : Polygonum cuspidatum extract induced ME-180 cell death in a dose- and time-dependent manner. In the cells treated with Pc, the population of cells at sub-G1 phase significantly increased, and the condensed nuclei, apoptotic bodies and nucleosome-sized DNA were detected. Moreover, reduction in mitochondrial membrane potential was detected. Conclusion : Polygonum cuspidatum extract inhibits the growth and proliferation of ME-180 cells by apoptotic induction and facilitates its activity initiated by depolarization of mitochondria.

• Clinical and Experimental Reproductive Medicine
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• v.49 no.2
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• pp.87-92
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• 2022

Objective: The aim of this study was to determine the effects of melatonin and selenium in freezing extenders on frozen-thawed rat sperm. Methods: Semen samples were collected from 20 adult male Wistar albino rats. Following dilution, the samples were divided into six groups: four cryopreserved groups with 1 mM and 0.5 mM melatonin and selenium supplements, and two fresh and cryopreserved control groups. The rapid freezing technique was used to freeze the samples. Flow cytometry was used to assess plasma membrane integrity, mitochondrial membrane potential, and DNA damage, while computer-assisted sperm analysis was used to assess motility. Results: Total motility was higher in the 1 mM melatonin supplementation group than in the cryopreserved control group (mean±standard error of the mean, 69.89±3.05 vs. 59.21±1.31; p≤0.05). The group with 1 mM selenium had the highest plasma membrane integrity (42.35%±1.01%). The cryopreserved group with 0.5 mM selenium had the highest mitochondrial membrane potential, whereas the cryopreserved control group had the lowest (45.92%±4.53% and 39.45%±3.52%, respectively). Conclusion: Cryopreservation of rat semen supplemented with 1 mM melatonin increased sperm motility after freeze-thawing, while supplementation with 0.5 mM selenium increased mitochondrial activity.

• Archives of Pharmacal Research
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• v.29 no.12
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• pp.1140-1146
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• 2006

Ceramide analogs are potential chemotherapeutic agents. We report that a ceramide analog induces apoptosis in human prostate cancer cells. The ceramide analog induced cell death through an apoptotic mechanism, which was demonstrated by DNA fragmentation, the cleavage of poly ADP ribose polymerase (PARP), and a loss of membrane asymmetry. Treating the cells with ceramide analog resulted in the release of various proapoptotic mitochondrial proteins including cytochrome c and Smac/DIBLO into the cytosol, and a decrease in the mitochondrial membrane potential. In addition, the ceramide analog decreased the phospho-Akt and phospho-Bad levels. The expression of the antiapoptotic Bcl-2 decreased slightly with increasing Bax to Bcl-2 ratio. These results suggest that the ceramide analog induces apoptosis by regulating multiple signaling pathways that involve the mitochondrial pathway.

• The Korean Journal of Physiology and Pharmacology
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• v.24 no.3
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• pp.223-232
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• 2020

Sesamin, a lipid-soluble lignin originally isolated from sesame seeds, which induces cancer cell apoptosis and autophagy. In the present study, has been reported that sesamin induces apoptosis via several pathways in human lung cancer cells. However, whether mitophagy is involved in sesamin induced lung cancer cell apotosis remains unclear. This study, the anticancer activity of sesamin in lung cancer was studied by reactive oxygen species (ROS) and mitophagy. A549 cells were treated with sesamin, and cell viability, migration ability, and cell cycle were assessed using the CCK8 assay, scratch-wound test, and flow cytometry, respectively. ROS levels, mitochondrial membrane potential, and apoptosis were examined by flow cytometric detection of DCFH-DA fluorescence and by using JC-1 and TUNEL assays. The results indicated that sesamin treatment inhibited the cell viability and migration ability of A549 cells and induced G₀/G₁ phase arrest. Furthermore, sesamin induced an increase in ROS levels, a reduction in mitochondrial membrane potential, and apoptosis accompanied by an increase in cleaved caspase-3 and cleaved caspase-9. Additionally, sesamin triggered mitophagy and increased the expression of PINK1 and translocation of Parkin from the cytoplasm to the mitochondria. However, the antioxidant N-acetyl-L-cysteine clearly reduced the oxidative stress and mitophagy induced by sesamin. Furthermore, we found that cyclosporine A (an inhibitor of mitophagy) decreased the inhibitory effect of sesamin on A549 cell viability. Collectively, our data indicate that sesamin exerts lethal effects on lung cancer cells through the induction of ROS-mediated mitophagy and mitochondrial apoptosis.

• Animal Bioscience
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• v.35 no.2
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• pp.166-176
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• 2022

Objective: Sperm is particularly susceptible to reactive oxygen species (ROS) stress. Glutathione (GSH) is an endogenous antioxidant that regulates sperm redox homeostasis. However, it is not clear whether boar sperm could utilize cysteine for synthesis GSH to protect sperm quality from ROS damage. Therefore, the present study was undertaken to elucidate the mechanism of how cysteine is involved in protecting boar sperm quality during liquid storage. Methods: Sperm motility, membrane integrity, lipid peroxidation, 4-hydroxyIlonenal (4-HNE) modifications, mitochondrial membrane potential, as well as the levels of ROS, GSH, and, ATP were evaluated. Moreover, the enzymes (GCLC: glutamate cysteine ligase; GSS: glutathione synthetase) that are involved in glutathione synthesis from cysteine precursor were detected by western blotting. Results: Compared to the control, addition of 1.25 mM cysteine to the liquid storage significantly increased boar sperm progressive motility, straight-line velocity, curvilinear velocity, beat-cross frequency, membrane integrity, mitochondrial membrane potential, ATP level, acrosome integrity, activities of superoxide dismutase and catalase, and GSH level, while reducing the ROS level, lipid peroxidation and 4-HNE modifications. It was also observed that the GCLC and GSS were expressed in boar sperm. Interestingly, when we used menadione to induce sperm with ROS stress, the menadione associated damages were observed to be reduced by the cysteine supplementation. Moreover, compared to the cysteine treatment, the γ-glutamylcysteine synthetase (γ-GCS) activity, GSH level, mitochondrial membrane potential, ATP level, membrane integrity and progressive motility in boar sperm were decreased by supplementing with an inhibitor of GSH synthesis, buthionine sulfoximine. Conclusion: These data suggest that boar sperm could biosynthesize the GSH from cysteine in vitro. Therefore, during storage, addition of cysteine improves boar sperm quality via enhancing the GSH synthesis to resist ROS stress.

• BMB Reports
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• v.53 no.12
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• pp.658-663
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• 2020

The N-myc downstream regulated gene (NDRG) family members are dysregulated in several tumors. Functionally, NDRGs play an important role in the malignant progression of cancer cells. However, little is known about the potential implications of NDRG4 in pancreatic ductal adenocarcinoma (PDAC). The aim of the current study was to elucidate the expression pattern of NDRG4 in PDAC and evaluate its potential cellular biological effects. Here, we firstly report that epigenetic-mediated silencing of NDRG4 promotes PDAC by regulating mitochondrial function. Data mining demonstrated that NDRG4 was significantly down-regulated in PDAC tissues and cells. PDAC patients with low NDRG4 expression showed poor prognosis. Epigenetic regulation by DNA methylation was closely associated with NDRG4 down-regulation. NDRG4 overexpression dramatically suppressed PDAC cell growth and metastasis. Further functional analysis demonstrated that up-regulated NDRG4 in SW1990 and Canpan1 cells resulted in attenuated mitochondrial function, including reduced ATP production, decreased mitochondrial membrane potential, and increased fragmented mitochondria. However, opposite results were obtained for HPNE cells with NDRG4 knockdown. These results indicate that hypermethylation-driven silencing of NDRG4 can promote PDAC by regulating mitochondrial function and that NDRG4 could be as a potential biomarker for PDAC patients.

• International Journal of Oral Biology
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• v.42 no.2
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• pp.55-61
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• 2017

Recent studies indicate that mitochondria are an important source of reactive oxygen species (ROS) in the spinal dorsal horn. In our previous study, application of malate, a mitochondrial electron transport complex I substrate, induced a membrane depolarization, which was inhibited by pretreatment with ROS scavengers. In the present study, we used patch clamp recording in the substantia geletinosa (SG) neurons of spinal slices, to investigate the cellular mechanism of mitochondrial ROS on neuronal excitability. DNQX (an AMPA receptor antagonist) and AP5 (an NMDA receptor antagonist) decreased the malate-induced depolarization. In an external calcium free solution and addition of tetrodotoxin (TTX) for blockade of synaptic transmission, the malate-induced depolarization remained unchanged. In the presence of DNQX, AP5 and AP3 (a group I metabotropic glutamate receptor (mGluR) antagonist), glutamate depolarized the membrane potential, which was suppressed by PBN. However, oligomycin (a mitochondrial ATP synthase inhibitor) or PPADS (a P2 receptor inhibitor) did not affect the substrates-induced depolarization. These results suggest that mitochondrial substrate-induced ROS in SG neuron directly acts on the postsynaptic neuron, therefore increasing the ion influx via glutamate receptors.