• BMB Reports
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• v.56 no.9
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• pp.520-525
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• 2023

Alzheimer's disease (AD) is a progressive neurodegenerative disease characterized by cognitive decline. Several recent studies demonstrated that impaired adult neurogenesis could contribute to AD-related cognitive impairment. Adult subventricular zone (SVZ) neurogenesis, which occurs in the lateral ventricles, plays a crucial role in structural plasticity and neural circuit maintenance. Alterations in adult SVZ neurogenesis are early events in AD, and impaired adult neurogenesis is influenced by the accumulation of intracellular Aβ. Although Aβ-overexpressing transgenic 5XFAD mice are an AD animal model well representative of Aβ-related pathologies in the brain, the characterization of altered adult SVZ neurogenesis following AD progression in 5XFAD mice has not been thoroughly examined. Therefore, we validated the characterization of adult SVZ neurogenesis changes with AD progression in 2-, 4-, 8-, and 11-monthold male 5XFAD mice. We first investigated the Aβ accumulation in the SVZ using the 4G8 antibody. We observed intracellular Aβ accumulation in the SVZ of 2-month-old 5XFAD mice. In addition, 5XFAD mice exhibited significantly increased Aβ deposition in the SVZ with age. Next, we performed a histological analysis to investigate changes in various phases of adult neurogenesis, such as quiescence, proliferation, and differentiation, in SVZ. Compared to age-matched wild-type (WT) mice, quiescent neural stem cells were reduced in 5XFAD mice from 2-11 months of age. Moreover, proliferative neural stem cells were decreased in 5XFAD mice from 2 to 8 months of age. Furthermore, differentiations of neuroblasts were diminished in 5XFAD mice from 2-11 months of age. Intriguingly, we found that adult SVZ neurogenesis was reduced with aging in healthy mice. Taken together, our results revealed that impairment of adult SVZ neurogenesis appears with aging or AD progression.

• BMB Reports
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• v.42 no.10
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• pp.667-672
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• 2009

Plasma concentrations of adiponectin have been shown to be decreased in patients with obesity, cardiovascular diseases, hypertension and metabolic syndrome. Recent studies have found that adiponectin reduces lipid accumulation in macrophage foam cells which may impact the development of atherosclerosis. However, it remains unclear whether adiponectin is involved in the process of lipid accumulation during myogenesis. Using C2C12 myoblasts, we investigated the effect of adiponectin on intramyocellular lipid accumulation during myogenesis. The results showed that intracellular lipid accumulation is significantly decreased during C2C12 differentiation, apparently due to increased fatty acid oxidation and decreased fatty acid synthesis during this process. C2C12 cells transiently transfected with adiponectin gene showed reduced lipid accumulation as compared to controls. Further experiments demonstrated that adiponectin can suppress lipid accumulation by increasing fatty acid oxidation during C2C12 myogenesis.

• The Korean Journal of Physiology and Pharmacology
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• v.2 no.3
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• pp.353-359
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• 1998

In gastrointestinal smooth muscle, muscarinic stimulation by carbachol (CCh) activates nonselective cation channel current ($I_{CCh}$) which is facilitated by intracellular [$Ca^{2+}$] increase. Caffeine is widely used in experiments to mobilize $Ca^{2+}$ from intracellular stores. This study shows a strong inhibitory effect of caffeine on $I_{CCh}$ in guinea-pig gastric myocyte. In this study, the underlying mechanism of the inhibitory effect of caffeine was investigated. $I_{CCh}$ was completely suppressed by the addition of caffeine (10 mM) to the superfusing solution. Inhibition of $I_{CCh}$ by caffeine was not related to the intracellular cAMP accumulation which was expected from the phosphodiesterase-inhibiting effect of caffeine. The blockade of $InsP_3-induced$ $Ca^{2+}$ release by heparin had no significant effects on the activation of $I_{CCh}$. When the same cationic current had been induced by intracellular dialysis of $GTP[{\gamma}S]$ in order to bypass the muscarinic receptor, the inhibitory effect of caffeine was significantly attenuated. The results of this study indicate that both intracellular signalling pathways for $I_{CCh}$, proximal and distal to G-protein activation, are suppressed by caffeine. A major inhibition was observed at the proximal level.

• Molecules and Cells
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• v.26 no.1
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• pp.18-25
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• 2008

Arsenic trioxide (ATO) can affect many biological functions such as apoptosis and differentiation in various cells. We investigated the involvement of ROS and GSH in ATO-induced HeLa cell death using ROS scavengers, especially N-acetylcysteine (NAC). ATO increased intracellular ${O_2}^{{\cdot}-}$ levels and reduced intracellular GSH content. The ROS scavengers, Tempol, Tiron and Trimetazidine, did not significantly reduce levels of ROS or GSH depletion in ATO-treated HeLa cells. Nor did they reduce the apoptosis induced by ATO. In contrast, treatment with NAC reduced ROS levels and GSH depletion in the ATO-treated HeLa cells and prevented ATO-induced apoptosis. Treatment with exogenous SOD and catalase reduced the depletion of GSH content in ATO-treated cells. Catalase strongly protected the cells from ATO-induced apoptosis. In addition, treatment with SOD, catalase and NAC slightly inhibited the G1 phase accumulation induced by ATO. In conclusion, NAC protects HeLa cells from apoptosis induced by ATO by up-regulating intracellular GSH content and partially reducing the production of ${O_2}^{{\cdot}-}$.

• Journal of Microbiology and Biotechnology
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• v.34 no.4
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• pp.783-794
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• 2024

The antifungal activity of fisetin against Candida albicans is explored, elucidating a mechanism centered on membrane permeabilization and ensuing disruption of pH homeostasis. The Minimum Inhibitory Concentration (MIC) of fisetin, indicative of its interaction with the fungal membrane, increases in the presence of ergosterol. Hoechst 33342 and propidium-iodide staining reveal substantial propidium-iodide accumulation in fisetin-treated C. albicans cells at their MIC, with crystal violet uptake assays confirming fisetin-induced membrane permeabilization. Leakage analysis demonstrates a significant release of DNA and proteins in fisetin-treated cells compared to controls, underscoring the antifungal effect through membrane disruption. Green fluorescence, evident in both the cytoplasm and vacuoles of fisetin-treated cells under BCECF, AM staining, stands in contrast to controls where only acidic vacuoles exhibit staining. Ratiometric pH measurements using BCECF, AM reveal a noteworthy reduction in intracellular pH in fisetin-treated cells, emphasizing its impact on pH homeostasis. DiBAC4(3) uptake assays demonstrate membrane hyperpolarization in fisetintreated cells, suggesting potential disruptions in ion flux and cellular homeostasis. These results provide comprehensive insights into the antifungal mechanisms of fisetin, positioning it as a promising therapeutic agent against Candida infections.

• Natural Product Sciences
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• v.25 no.3
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• pp.255-260
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• 2019

Piper nigrum L. (Piperaceae), which is a well-known food seasoning, has been used as a traditional medicine for the treatment of vomiting, abdominal pain, diarrhea and anorexia in Korea, China and Japan. Methanol extract from the fruit of P. nigrum was successively partitioned as n-hexane, methylene chloride, ethyl acetate, n-butanol and $H_2O$ soluble fractions. Among those fractions the ethyl acetate soluble fraction showed the most potent DPPH radical scavenging activity, and piperine was isolated from the ethyl acetate fraction. To know the antioxidant activity of piperine, we tested the activities of superoxide dismutase (SOD) and catalase together with oxidative stress tolerance and intracellular ROS level in Caenorhabditis elegans. To investigate whether piperine-mediated increased stress tolerance was due to regulation of stress-response gene, we quantified SOD-3 expression using transgenic strain including CF1553. Consequently, piperine enhanced SOD and catalase activities of C. elegans, and reduced intracellular ROS accumulation in a dose-dependent manner. Moreover, piperine-treated CF1553 worms exhibited significantly higher SOD-3::GFP intensity.

• Journal of Yeungnam Medical Science
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• v.38 no.2
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• pp.83-94
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• 2021

The global obesity epidemic and the growing elderly population largely contribute to the increasing incidence of type 2 diabetes. Insulin resistance acts as a critical link between the present obesity pandemic and type 2 diabetes. Naturally occurring reactive oxygen species (ROS) regulate intracellular signaling and are kept in balance by the antioxidant system. However, the imbalance between ROS production and antioxidant capacity causes ROS accumulation and induces oxidative stress. Oxidative stress interrupts insulin-mediated intracellular signaling pathways, as supported by studies involving genetic modification of antioxidant enzymes in experimental rodents. In addition, a close association between oxidative stress and insulin resistance has been reported in numerous human studies. However, the controversial results with the use of antioxidants in type 2 diabetes raise the question of whether oxidative stress plays a critical role in insulin resistance. In this review article, we discuss the relevance of oxidative stress to insulin resistance based on genetically modified animal models and human trials.

• The Journal of Korean Medicine
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• v.41 no.4
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• pp.64-71
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• 2020

Objectives: This study was done to look into whether Nrf2 take some role in the anti-lipogenic effect of kaurenoic acid in a nonalcoholic fatty liver disease (NAFLD) cellular model. Materials and Methods: We measured the effect of kaurenoic acid on intracellular steatosis and Nrf2 activation. Next, the effect of kaurenoic acid on SREBP-1c and some lipogenic genes in palmitate treated HepG2 cells with or without Nrf2 silencing. Results: The increased SREBP-1c expression was significantly decreased by concomitant kaurenoic acid treatment in non-targeting negative control siRNA transfected HepG2 cells. However, kaurenoic acid did not significantly inhibited increased SREBP-1c level in Nrf2 specific siRNA transfected HepG2 cells Conclusions: Kaurenoic acid has a potential to activate Nrf2, which may suppress SREBP-1c mediated intracellular steatosis in HepG2 cells.

• Korean Chemical Engineering Research
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• v.60 no.3
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• pp.392-397
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• 2022

Methane is one of the major greenhouse gases, recently, the biotechnological conversion from methane to high-value added chemicals have emerged as an effort to reduce methane gas emission. In this study, we optimized ectoine bio-milking conditions in which cells were repeatedly used to improve intracellular and extracellular ectoine yield from methane by using Methylomicrobium alcaliphilum 20ZDP2. First, the cultivation and intracellular ectoine accumulation conditions were optimized with respect to the growth phase and medium salinity to achieve the highest yield of synthesis. Second, ectoine excretion was optimized by determining the ectoine secretion time (15 min) in appropriate medium salinity under hypoosmotic conditions (1% NaCl). Finally, bio-milking of ectoine was successfully repeated more than 10 times using M. alcaliphilum 20ZDP2, and the ectoine yield was improved up to 129.29 mg/ DCW g.

• Journal of Korean Medicine for Obesity Research
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• v.24 no.1
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• pp.1-12
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• 2024

Objectives: Ephedrae herba (EH) and Coicis semen (CS) has been frequently prescribed for the treatment of obesity. However, effects of combinational extracts of these two herbs on non-alcoholic fatty liver disease are unknown. The aim of the present study was to investigate the effects of EH and CS on lipid accumulation and glucose absorption in free fatty acids (FFAs) or palmitic acid (PA)-treated HepG2 cells. Methods: Five samples of EH and CS were extracted by combination ratios (S1=0:100, S2=25:75, S3=50:50, S4=75:25, S5=100:0). Oil Red O staining was used to measure lipid accumulation in FFAs-induced steatosis cells. Intracellular triglycerides and total cholesterol levels were measured in FFAs-induced steatotic HepG2 cells. In PA-treated cells, intracellular 2-NBDG was detected using a fluorescence microplate reader and flow cytometry. Phosphorylation of key metabolism-related factors of AMP-activated protein kinase and acetyl-CoA carboxylase, expression of key lipid synthesis-related factors carnitine palmitoyltransferase 1 alpha (CPT1α), sterol regulatory element-binding protein 1 (SREBP1), peroxisome proliferator-activated receptor gamma (PPARγ) and CCAAT enhancer binding protein alpha (C/EBPα) were confirmed by western blot. Results: Treatment of EH-CS combination in the FFAs-induced steatotic HepG2 cells significantly reduced lipid accumulation. As the relative ratio of Ephedrae herba increased, the lipid-lowering effects of the combination were increased. However, S1 and S5 of Ephedrae herba and Coicis semen did not significantly reduce triglycerides and total cholesterol induced by FFAs. However, the combination of Ephedrae herba and Coicis semen restored glucose absorption in PA-induced HepG2 cells. Major makers of SREBP1, PPARγ, C/EBPα, and CPT1α expression tended to decrease with EH ratio. Conclusions: The EH-CS combination has advantages over sole EH and CS extracts in improving lipid and glucose metabolism in liver steatosis models.