• Molecules and Cells
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• 제46권12호
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• pp.727-735
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• 2023

Stem cells require high amounts of energy to replicate their genome and organelles and differentiate into numerous cell types. Therefore, metabolic stress has a major impact on stem cell fate determination, including self-renewal, quiescence, and differentiation. Lysosomes are catabolic organelles that influence stem cell function and fate by regulating the degradation of intracellular components and maintaining cellular homeostasis in response to metabolic stress. Lysosomal functions altered by metabolic stress are tightly regulated by the transcription factor EB (TFEB) and TFE3, critical regulators of lysosomal gene expression. Therefore, understanding the regulatory mechanism of TFEB-mediated lysosomal function may provide some insight into stem cell fate determination under metabolic stress. In this review, we summarize the molecular mechanism of TFEB/TFE3 in modulating stem cell lysosomal function and then elucidate the role of TFEB/TFE3-mediated transcriptional activity in the determination of stem cell fate under metabolic stress.

• Molecules and Cells
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• 제46권11호
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• pp.655-663
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• 2023

Autophagy dysfunction is associated with human diseases and conditions including neurodegenerative diseases, metabolic issues, and chronic infections. Additionally, the decline in autophagic activity contributes to tissue and organ dysfunction and aging-related diseases. Several factors, such as down-regulation of autophagy components and activators, oxidative damage, microinflammation, and impaired autophagy flux, are linked to autophagy decline. An autophagy flux impairment (AFI) has been implicated in neurological disorders and in certain other pathological conditions. Here, to enhance our understanding of AFI, we conducted a comprehensive literature review of findings derived from two well-studied cellular stress models: glucose deprivation and replicative senescence. Glucose deprivation is a condition in which cells heavily rely on oxidative phosphorylation for ATP generation. Autophagy is activated, but its flux is hindered at the autolysis step, primarily due to an impairment of lysosomal acidity. Cells undergoing replicative senescence also experience AFI, which is also known to be caused by lysosomal acidity failure. Both glucose deprivation and replicative senescence elevate levels of reactive oxygen species (ROS), affecting lysosomal acidification. Mitochondrial alterations play a crucial role in elevating ROS generation and reducing lysosomal acidity, highlighting their association with autophagy dysfunction and disease conditions. This paper delves into the underlying molecular and cellular pathways of AFI in glucose-deprived cells, providing insights into potential strategies for managing AFI that is driven by lysosomal acidity failure. Furthermore, the investigation on the roles of mitochondrial dysfunction sheds light on the potential effectiveness of modulating mitochondrial function to overcome AFI, offering new possibilities for therapeutic interventions.

• Biomolecules & Therapeutics
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• 제30권4호
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• pp.348-359
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• 2022

Gastric adenocarcinoma is among the top causes of cancer-related death and is one of the most commonly diagnosed carcinomas worldwide. Benzyl isothiocyanate (BITC) has been reported to inhibit the gastric cancer metastasis. In our previous study, BITC induced apoptosis in AGS cells. The purpose of the present study was to investigate the effect of BITC on autophagy mechanism in AGS cells. First, the AGS cells were treated with 5, 10, or 15 μM BITC for 24 h, followed by an analysis of the autophagy mechanism. The expression level of autophagy proteins involved in different steps of autophagy, such as LC3B, p62/SQSTM1, Atg5-Atg12, Beclin1, p-mTOR/mTOR ratio, and class III PI3K was measured in the BITC-treated cells. Lysosomal function was investigated using cathepsin activity and Bafilomycin A1, an autophagy degradation stage inhibitor. Methods including qPCR, western blotting, and immunocytochemistry were employed to detect the protein expression levels. Acridine orange staining and omnicathepsin assay were conducted to analyze the lysosomal function. siRNA transfection was performed to knock down the LC3B gene. BITC reduced the level of autophagy protein such as Beclin 1, class III PI3K, and Atg5-Atg12. BITC also induced lysosomal dysfunction which was shown as reducing cathepsin activity, protein level of cathepsin, and enlargement of acidic vesicle. Overall, the results showed that the BITC-induced AGS cell death mechanism also comprises the inhibition of the cytoprotective autophagy at both initiation and degradation steps.

• Applied Biological Chemistry
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• 제20권2호
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• pp.175-181
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• 1977

돼지 백혈구(白血球) Iysoromal enzyme의 latency를 서로 다른 농도의 sucrose용액(0.0125-0.25M)으로서 조사하고 각(各) sedimentation fraction에 분포되어 있는 효소들의 specific activity, pH optima 및 activation energy를 측정하였다.

• 대한약리학회지
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• 제25권1호
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• pp.75-85
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• 1989

면역 보체가 결합되어 있는 zymosan에 의하여 활성화된 다형핵 백혈구에서 세포 투과성 물질인 N-ethylmaleiamide과 $Hg^{++}$은 superoxide 라디칼 생성, NADPH oxidase 활성도 및 lysosomal enzyme (lactic dehydrogenase, ${\beta}-glucuronidase$)의 유리를 억제하였다. 세포막 단백에 특이적인 p-chloromercuribenzoic acid와 p-chloromercuribenzenesulfonic acid는 superoxide 라디칼 생성에 영향을 주지 않았으나 NADPH oxidase 활성도와 lysosomal enzyme의 유리를 억제하였다. 식작용 중에 세포막과 세포내의 sulfhydryl기는 반응시간에 따라 점진적으로 감소하였다. N-ethylmaleiamide와 $Hg^{++}$은 세포막과 세포내의 sulfhydryl기를 모두 감소시켰다. P-Chloromercuribenzoic acid와 p-chloromercuribenzenesulfonic acid는 세포막의 sulfhydryl기를 유의하게 감소시켰으나 세포내 용해성 sulfhydryl기에는 영향을 주지않았다. Cysteine과 mercaptopropionylglycine는 superoxide 라디칼의 생성과 lysosomal enzyme의 유리를 억제하였다. Gluthathione은 superoxide생성에 영향을 주지 않았으나 뚜렷하게 lactic dehydrogenase의 유리를 억제하였다. N-ethylmaleiamide에 의한 superoxide 생성의 억제는 cysteine과 mercaptopropionyl-glycine에 의하여 반전되었으나 gluthathione의 영향은 없었다. N-ethylamleiamide에 의한 NADPH oxidase의 비활성화는 gluthathione, cysteine과 mercaptopropionylglycine에 의하여 저해되었다. Carbachol에 의하여 항진된 superoxide 라디칼 생성은 N-ethylamleiamide에 의하여 완전히 억제되었고, atropine에 의하여 길항되었다. 그러므로, 외부 자극에 대한 다형핵 백혈구 반응의 표현은 sulfhydryl기의 양의 변화와 연관이 있을 것으로 시사되었다. Lysosomal enzyme 유리는 세포막과 세포내의 sulfhydryl기에 의하여, 이에 반하여 superoxide생성은 세포내 sulfhydryl기에 의해서 영향받을 것으로 추정되었다.

• International Journal of Oral Biology
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• 제43권1호
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• pp.23-27
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• 2018

Increased intracellular levels of $Ca^{2+}$ are generally thought to negatively regulate lipolysis in mature adipocytes, whereas store-operated $Ca^{2+}$ entry was recently reported to facilitate lipolysis and attenuate lipotoxicity by inducing lipophagy. Transient receptor potential mucolipin1 (TRPML1), a $Ca^{2+}$-permeable non-selective cation channel, is mainly expressed on the lysosomal membrane and plays key roles in lysosomal homeostasis and membrane trafficking. However, the roles of TRPML1 in lipolysis remains unclear. In this study, we examined whether the channel function of TRPML1 induces lipolysis in mature adipocytes. We found that treatment of mature adipocytes with ML-SA1, a specific agonist of TRPML1, solely upregulated extracellular glycerol release, but not to the same extent as isoproterenol. In addition, knockdown of TRPML1 in mature adipocytes significantly reduced autophagic flux, regardless of ML-SA1 treatment. Our findings demonstrate that the channel function of TRPML1 partially contributes to lipid metabolism and autophagic membrane trafficking, suggesting that TRPML1, particularly the channel function of TRPML1, is as therapeutic target molecule for treating obesity.

• Journal of Microbiology and Biotechnology
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• 제27권2호
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• pp.372-379
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• 2017

The transport of lysosomal enzymes into the lysosomes depends on the phosphorylation of their chains and the binding of the phosphorylated residues to mannose-6-phosphate receptors. The efficiency of separation depends more on the phosphodiesterases (PDEs) than on the activity of the phosphorylation of mannose residues and can be determined in vitro. PDEs play important roles in regulation of the activation of lysosomes. The expression of proteins was confirmed by western blotting. All PDE4 series protein expression was reduced in high concentrations of rolipram. As a result of observing the fluorescence intensity after rolipram treatment, the lysosomal enzyme was activated at low concentrations and suppressed at high concentrations. High concentrations of rolipram recovered the original function. Antimicrobial activity was not shown in either 10 or $100{\mu}M$ concentrations of rolipram in treated HeLa cells in vitro. However, the higher anticancer activity at lower rolipram concentration was shown in lysosomal enzyme treated with $10{\mu}M$ of rolipram. The anticancer activity was confirmed through cathepsin B and D assay. Tranfection allowed examination of the relationship between PDE4 and lysosomal activity in more detail. Protein expression was confirmed to be reduced. Fluorescence intensity showed decreased activity of lysosomes and ROS in cells transfected with the antisense sequences of PDE4 A, B, C, and D. PDE4A showed anticancer activity, whereas lysosome from cells transfected with the antisense sequences of PDE4 B, C, and D had decreased anticancer activity. These results showed the PDE4 A, B, C, and D are conjunctly related with lysosomal activity.

• The Korean Journal of Physiology and Pharmacology
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• 제27권4호
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• pp.311-323
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• 2023

Ion homeostasis, which is regulated by ion channels, is crucial for intracellular signaling. These channels are involved in diverse signaling pathways, including cell proliferation, migration, and intracellular calcium dynamics. Consequently, ion channel dysfunction can lead to various diseases. In addition, these channels are present in the plasma membrane and intracellular organelles. However, our understanding of the function of intracellular organellar ion channels is limited. Recent advancements in electrophysiological techniques have enabled us to record ion channels within intracellular organelles and thus learn more about their functions. Autophagy is a vital process of intracellular protein degradation that facilitates the breakdown of aged, unnecessary, and harmful proteins into their amino acid residues. Lysosomes, which were previously considered protein-degrading garbage boxes, are now recognized as crucial intracellular sensors that play significant roles in normal signaling and disease pathogenesis. Lysosomes participate in various processes, including digestion, recycling, exocytosis, calcium signaling, nutrient sensing, and wound repair, highlighting the importance of ion channels in these signaling pathways. This review focuses on different lysosomal ion channels, including those associated with diseases, and provides insights into their cellular functions. By summarizing the existing knowledge and literature, this review emphasizes the need for further research in this field. Ultimately, this study aims to provide novel perspectives on the regulation of lysosomal ion channels and the significance of ion-associated signaling in intracellular functions to develop innovative therapeutic targets for rare and lysosomal storage diseases.

• Ocean and Polar Research
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• 제34권2호
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• pp.137-149
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• 2012

남해의 광양만과 진해만에 서식하는 자연산 참굴의 건강성 평가를 위해 세포성 면역을 담당하는 혈구의 기능들을 유세포 분석기와 Neutral Red Retention(NRR) assay를 이용하여 신속, 정확하게 측정하였다. 광양만과 진해만의 안쪽과 바깥쪽에 서식하는 자연산 참굴의 혈구를 유세포 분석기를 이용하여 형태학적 특성에 따라 혈구의 종류를 분류하고, 혈구 종류별 수, 사멸률, DNA 손상도, 식세포능을 측정하였다. 또한 NRR assay를 이용하여 혈구의 lysosomal membrane stability를 측정하였다. 참굴의 혈구는 granulocytes, hyalinocytes, blast-like cells의 세 가지 종류로 분류되었다. 조사 지역 간의 혈구의 수, 사멸률, DNA 손상도는 유의적 차이가 없었지만, 식세포율과 lysosomal membrane stability와 같은 면역 관련 기능들은 유의적 차이가 있었다. 진해만은 내만과 외만 지역에 서식하는 참굴의 혈구 면역인자들 간에는 유의적 차이가 관찰되지 않았다. 이에 반해, 광양만에 서식하는 참굴은 내만 지역의 섬진대교가 외만 지역의 평산리 지역에 서식하는 참굴보다 낮은 식세포율과 낮은 lysosomal membrane stability를 보여 면역력이 저하되어 있는 것으로 추정된다. 하지만, 해양환경 변화와 시료의 면역력과의 상관관계를 이해하기 위해서는 조사지역의 환경적 특성이나 오염정도, 그리고 시료 내의 오염물질 축적량 등의 객관적인 분석 결과와의 종합적인 고찰이 필요할 것이다. 유세포 분석기와 NRR assay를 이용한 참굴 혈구 집단의 형태 변화 및 면역능 측정 기술은 시료의 전처리 없이 빠른 시간 내에 세포의 특성을 분석할 수 있는 유용한 분석 tool로 활용될 수 있음을 확인하였다.

• 대한한방내과학회지
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• 제19권1호
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• pp.491-504
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• 1998

Mainly side effects of antitumor chemotheraphy are fatigue, G-Ⅰ trouble(such as vomitting, nausea, diarrhea) and reduction of medullary function etc. Differentiated from syndromes in oriental medicine, above symptoms are recognized to 'Deficiency of both ki(vital energy) and blood'. And SDT(Sipjeondaebotang) has been widely used in 'Deficiency of both ki(vital energy) and blood'. Dr. Mun's SDTG(Sipjeondaebotanggamibang) consists of SDT plus several herb medicines-these have antitumor effect and reduce chemotherapheutic side effect. This experiment was undertaken to study the effects of SDTG on chemotherapheutic side effect and cytotoxicity. The results obtained in this study were as follows: Antitumor activities of the ethanol extract from SDTG(Sipjeondaebotanggamibang) and MMC(Mytomycin) on ascitis form of calcinoma in mice is a little improved. Especialy mean survival times of the group of SDTG(200mg/kg) and MMC(0.1mg/kg) is improved over 50%. When SDTG and MMC is administrated together, the weight of tumor is more decreased than MMC alone. The effect of the ethanol extract from SDTG and MMC on the lysosomal enzymes in Ehrich ascites carcinoma cell are more significantly improved than MMC alone. SDTG extract increases both NKcell conjugation and cyto-lysis against target cell. According to the above results it is recognized that SDTG increases the chemotherapheutic cytotoxicity of MMC and the activity of NKcell.