• 제목/요약/키워드: autophagy

검색결과 465건 처리시간 0.024초

Activation of Autophagy Pathway Suppresses the Expression of iNOS, IL6 and Cell Death of LPS-Stimulated Microglia Cells

  • Han, Hye-Eun;Kim, Tae-Kyung;Son, Hyung-Jin;Park, Woo Jin;Han, Pyung-Lim
    • Biomolecules & Therapeutics
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    • 제21권1호
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    • pp.21-28
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    • 2013
  • Microglia play a role in maintaining and resolving brain tissue homeostasis. In pathological conditions, microglia release pro-inflammatory cytokines and cytotoxic factors, which aggravate the progression of neurodegenerative diseases. Autophagy pathway might be involved in the production of pro-inflammatory cytokines and cytotoxic factors in microglia, though details of the mechanism remain largely unknown. In the present study, we examined the role of the autophagy pathway in activated BV2 microglia cells. In BV2 cells, rapamycin treatment activated the formation of anti-LC3-labeled autophagosomes, whereas the ATG5 depletion using siRNA-ATG5 prevented the formation of LC3-labeled autophagosomes, indicating that BV2 cells exhibit an active classical autophagy system. When treated with LPS, BV2 cells expressed an increase of anti-LC3-labeled dots. The levels of LC3-labeled dots were not suppressed, instead tended to be enhanced, by the inhibition of the autophagy pathway with siRNA-ATG5 or wortmannin, suggesting that LPS-induced LC3-labeled dots in nature were distinct from the typical autophagosomes. The levels of LPS-induced expression of iNOS and IL6 were suppressed by treatment with rapamycin, and conversely, their expressions were enhanced by siRNA-ATG5 treatment. Moreover, the activation of the autophagy pathway using rapamycin inhibited cell death of LPS-stimulated microglia. These results suggest that although microglia possess a typical autophagy pathway, the glial cells express a non-typical autophagy pathway in response to LPS, and the activation of the autophagy pathway suppresses the expression of iNOS and IL6, and the cell death of LPS-stimulated microglia.

Proliferation of Toxoplasma gondii Suppresses Host Cell Autophagy

  • Lee, Youn-Jin;Song, Hyun-Ouk;Lee, Young-Ha;Ryu, Jae-Sook;Ahn, Myoung-Hee
    • Parasites, Hosts and Diseases
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    • 제51권3호
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    • pp.279-287
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    • 2013
  • Autophagy is a process of cytoplasmic degradation of endogenous proteins and organelles. Although its primary role is protective, it can also contribute to cell death. Recently, autophagy was found to play a role in the activation of host defense against intracellular pathogens. The aims of our study was to investigate whether host cell autophagy influences Toxoplasma gondii proliferation and whether autophagy inhibitors modulate cell survival. HeLa cells were infected with T. gondii with and without rapamycin treatment to induce autophagy. Lactate dehydrogenase assays showed that cell death was extensive at 36-48 hr after infection in cells treated with T. gondii with or without rapamycin. The autophagic markers, LC3 II and Beclin 1, were strongly expressed at 18-24 hr after exposure as shown by Western blotting and RT-PCR. However, the subsequent T. gondii proliferation suppressed autophagy at 36 hr post-infection. Pre-treatment with the autophagy inhibitor, 3-methyladenine (3-MA), down-regulated LC3 II and Beclin 1. The latter was also down-regulated by calpeptin, a calpain inhibitor. Monodansyl cadaverine (MDC) staining detected numerous autophagic vacuoles (AVs) at 18 hr post-infection. Ultrastructural observations showed T. gondii proliferation in parasitophorous vacuoles (PVs) coinciding with a decline in the numbers of AVs by 18 hr. FACS analysis failed to confirm the presence of cell apoptosis after exposure to T. gondii and rapamycin. We concluded that T. gondii proliferation may inhibit host cell autophagy and has an impact on cell survival.

Chracterization of THP-1 Cell Death Induced by Porphyromonas gingivalis Infection

  • Song, YuRi;Kim, SeYeon;Park, Mee Hee;Na, Hee Sam;Chung, Jin
    • International Journal of Oral Biology
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    • 제42권1호
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    • pp.17-23
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    • 2017
  • Background: Periodontitis is generally a chronic disorder characterized by the breakdown of tooth-supporting tissues. P. gingivalis, a Gram-negative anaerobic rod, is one of the major pathogens associated with periodontitis. Frequently, P. gingivalis infection leads to cell death. However, the correlation between P. gingivalis-induced cell death and periodontal inflammation remains to be elucidated. Among cell deaths, the death of immune cells appears to play a significant role in inflammatory response. Thus, the aim of this study was to examine P. gingivalis-induced cell death, focusing on autophagy and apoptosis in THP-1 cells. Methods: Human acute monocytic leukemia cell line (THP-1) was used for all experiments. Autophagy induced by P. gingivalis in THP-1 cells was examined by Cyto ID staining. Intracellular autophagic vacuoles were observed by fluorescence microscopy using staining Acridine orange (AO); and 3-methyladenine (3-MA) was used to inhibit autophagy. Total cell death was measured by LDH assay. Cytokine production was measured by an ELISA method. Results: P. gingivalis induced autophagy in an MOI-dependent manner in THP-1 cells, but 3-MA treatment decreased autophagy and increased the apoptotic blebs. P. gingivalis infection did not increase apoptosis compared to the control cells, whereas inhibition of autophagy by 3-MA significantly increased apoptosis in P. gingivalis-infected THP-1 cells. Inhibition of autophagy by 3-MA also increased total cell deaths and inflammatory cytokine production, including $IL-1{\beta}$ and $TNF-{\alpha}$. Conclusion: P. gingivalis induced autophagy in THP-1 cells, but the inhibition of autophagy by 3-MA stimulated apoptosis, leading to increased cell deaths and pro-inflammatory cytokines production. Hence, the modulation of cell deaths may provide a mechanism to fight against invading microorganisms in host cells and could be a promising way to control inflammation.

Comparative Study of Autophagy in Oxaliplatin-Sensitive and Resistant SNU-C5 Colon Cancer Cells

  • Boo, Sun-Jin;Piao, Mei Jing;Kang, Kyoung Ah;Zhen, Ao Xuan;Fernando, Pincha Devage Sameera Madushan;Herath, Herath Mudiyanselage Udari Lakmini;Lee, Seung Joo;Song, Seung Eun;Hyun, Jin Won
    • Biomolecules & Therapeutics
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    • 제30권5호
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    • pp.447-454
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    • 2022
  • Few studies have evaluated the role of autophagy in the development of oxaliplatin (OXT) resistance in colon cancer cells. In this study, we compared the role of autophagy between SNU-C5 colon cancer cells and OXT-resistant SNU-C5 (SNU-C5/OXTR) cells. At the same concentration of OXT, the cytotoxicity of OXT or apoptosis was significantly reduced in SNU-C5/OXTR cells compared with that in SNU-C5 cells. Compared with SNU-C5 cells, SNU-C5/OXTR cells exhibited low levels of autophagy. The expression level of important autophagy proteins, such as autophagy-related protein 5 (Atg5), beclin-1, Atg7, microtubule-associated proteins 1A/1B light chain 3B I (LC3-I), and LC3-II, was significantly lower in SNU-C5/OXTR cells than that in SNU-C5 cells. The expression level of the autophagy-essential protein p62 was also lower in SNU-C5/OXTR cells than in SNU-C5 cells. In SNU-C5/OXTR cells, the production of intracellular reactive oxygen species (ROS) was significantly higher than that in SNU-C5 cells, and treatment with the ROS scavenger N-acetylcysteine restored the reduced autophagy levels. Furthermore, the expression of antioxidant-related nuclear factor erythroid 2-related factor 2 transcription factor, heme oxygenase-1, and Cu/Zn superoxide dismutase were also significantly increased in SNU-C5/OXTR cells. These findings suggest that autophagy is significantly reduced in SNU-C5/OXTR cells compared with SNU-C5 cells, which may be related to the production of ROS in OXT-resistant cells.

Dexamethasone Interferes with Autophagy and Affects Cell Survival in Irradiated Malignant Glioma Cells

  • Komakech, Alfred;Im, Ji-Hye;Gwak, Ho-Shin;Lee, Kyue-Yim;Kim, Jong Heon;Yoo, Byong Chul;Cheong, Heesun;Park, Jong Bae;Kwon, Ji Woong;Shin, Sang Hoon;Yoo, Heon
    • Journal of Korean Neurosurgical Society
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    • 제63권5호
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    • pp.566-578
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    • 2020
  • Objective : Radiation is known to induce autophagy in malignant glioma cells whether it is cytocidal or cytoprotective. Dexamethasone is frequently used to reduce tumor-associated brain edema, especially during radiation therapy. The purpose of the study was to determine whether and how dexamethasone affects autophagy in irradiated malignant glioma cells and to identify possible intervening molecular pathways. Methods : We prepared p53 mutant U373 and LN229 glioma cell lines, which varied by phosphatase and tensin homolog (PTEN) mutational status and were used to make U373 stable transfected cells expressing GFP-LC3 protein. After performing cell survival assay after irradiation, the IC50 radiation dose was determined. Dexamethasone dose (10 μM) was determined from the literature and added to the glioma cells 24 hours before the irradiation. The effect of adding dexamethasone was evaluated by cell survival assay or clonogenic assay and cell cycle analysis. Measurement of autophagy was visualized by western blot of LC3-I/LC3-II and quantified by the GFP-LC3 punctuated pattern under fluorescence microscopy and acridine orange staining for acidic vesicle organelles by flow cytometry. Results : Dexamethasone increased cell survival in both U373 and LN229 cells after irradiation. It interfered with autophagy after irradiation differently depending on the PTEN mutational status : the autophagy decreased in U373 (PTEN-mutated) cells but increased in LN229 (PTEN wild-type) cells. Inhibition of protein kinase B (AKT) phosphorylation after irradiation by LY294002 reversed the dexamethasone-induced decrease of autophagy and cell death in U373 cells but provoked no effect on both autophagy and cell survival in LN229 cells. After ATG5 knockdown, radiation-induced autophagy decreased and the effect of dexamethasone also diminished in both cell lines. The diminished autophagy resulted in a partial reversal of dexamethasone protection from cell death after irradiation in U373 cells; however, no significant change was observed in surviving fraction LN229 cells. Conclusion : Dexamethasone increased cell survival in p53 mutated malignant glioma cells and increased autophagy in PTEN-mutant malignant glioma cell but not in PTEN-wildtype cell. The difference of autophagy response could be mediated though the phosphatidylinositol 3-kinase/AKT/mammalian target of rapamycin signaling pathway.

사람 폐 섬유아 세포에서 Brunfelsia grandiflora 에탄올 추출물이 Autophagy에 미치는 영향 (The Effect of Brunfelsia grandiflora Ethanol Extract on the Induction of Autophagy in Human Lung Fibroblasts)

  • 남향;김문무
    • 생명과학회지
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    • 제24권8호
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    • pp.837-842
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    • 2014
  • 이 연구의 목적은 사람 폐 섬유아세포인 IMR 90 에서 Brunfelsia grandiflora 에탄올 추출물(BGEE)이 SIRT1 및 p53 활성화를 통해 autophagy의 유도에 대한 효과를 조사한 것이다. BGEE는 $5{\mu}g/ml$ 이상의 농도에서 IMR 90 세포에서 세포독성을 나타내었다. 본 연구에서 처음으로 BGEE가 autophagy를 유도 하는 것이 발견되었다. 또한, BGEE는 $2.5{\mu}g/ml$ 이하에서 Beclin-1 및 $5{\mu}g/ml$ 이상에서 Atg7 의 활성화가 autophagy의 유도에 관여함을 확인하였다. 더욱이 BGEE는 autophagy와 관련된 단백질 발현을 조절하였는데 p53 및 p-p53 단백질 발현이 세포독성이 없는 농도의 BGEE존재하에서 감소되었다. 하였다. 반면에, SIRT1의 발현수준은 세포독성이 없는 농도의 BGEE로 처리된 IMR 90 세포에서 증가되었다. 더욱이 BGEE로 처리된 사람 페 섬유아세포에서 노화 마커의 지표인 SA-${\beta}$-gal staning이 감소되는 것이 관찰되었다. 이상의 발견들은 BGEE는 사람 폐 섬유아세포에서 p53 및 SIRT1의 조절을 통하여 autophagy 및 항노화 유발을 촉진 시키는 것을 시사하고 있다.

우울증에서 자가소화작용의 역할 (The Role of Autophagy in Depression)

  • 서미경;박성우;석대현
    • 생명과학회지
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    • 제32권10호
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    • pp.812-820
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    • 2022
  • 우울증은 우울한 기분, 무쾌감증, 피로 및 인지 기능 변화를 특징으로 하는 정신질환으로 일상 기능의 저하를 초래한다. 또한, 우울증은 개인의 삶뿐만 아니라 사회적으로도 심각하고 흔한 정신질환이므로 적극적인 치료가 필요하다. 자가소화작용은 정신질환의 병태생리학적 기전에 관여한다. 최근 연구에 따르면, 자가소화작용에 의한 세포사멸이 신경가소성에 영향을 주어 우울증을 유발하고, 항우울제가 자가소화작용을 조절한다고 알려져 있다. 자가소화작용은 용해소체를 통해 불필요한 세포소기관이나 단백질을 분해하고 제거하는 이화과정이다. 그리고, 세포의 항상성을 유지하는데 필수적이다. 자가소화작용은 스트레스 상황에서 활성화되며 우울증은 스트레스 관련 질병이다. 최근, 신경세포에서 자가소화작용 기전의 역할이 조사되고 있지만, 우울증의 자가소화작용은 완전히 연구되지 않았다. 이 리뷰에서 우울증의 병태생리학적 기전과 치료에 자가소화작용이 관여한다는 새로운 증거를 강조하고자 한다. 증거를 강조하기 위해 자가소화작용이 우울증과 관련되어 있음을 보여주는 임상 및 전임상 연구결과들을 소개한다. 우울증에 대한 자가소화작용의 관련성과 연구의 한계를 이해하는 것은 자가소화작용 조절이 항우울제 개발의 새로운 방향을 제공할 것으로 사료된다.

Autophagy as an Innate Immune Modulator

  • Oh, Ji Eun;Lee, Heung Kyu
    • IMMUNE NETWORK
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    • 제13권1호
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    • pp.1-9
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    • 2013
  • Autophagy is a fundamental cellular process in eukaryotic cells for maintaining homeostasis by degrading cellular proteins and organelles. Recently, the roles of autophagy have been expanded to immune systems, which in turn modulate innate immune responses. More specifically, autophagy acts as a direct effector for protection against pathogens, as well as a modulator of pathogen recognition and downstream signaling in innate immune responses. In addition, autophagy controls autoimmunity and inflammatory disorders by negative regulation of immune signaling. In this review, we focus on recent advances in the role of autophagy in innate immune systems.

Autophagy down-regulates NLRP3-dependent inflammatory response of intestinal epithelial cells under nutrient deprivation

  • Yun, Yewon;Baek, Ahruem;Kim, Dong-Eun
    • BMB Reports
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    • 제54권5호
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    • pp.260-265
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    • 2021
  • Dysregulation of inflammation induced by noninfectious stress conditions, such as nutrient deprivation, causes tissue damage and intestinal permeability, resulting in the development of inflammatory bowel diseases. We studied the effect of autophagy on cytokine secretion related to intestinal permeability under nutrient deprivation. Autophagy removes NLRP3 inflammasomes via ubiquitin-mediated degradation under starvation. When autophagy was inhibited, starvation-induced NLRP3 inflammasomes and their product, IL-1β, were significantly enhanced. A prolonged nutrient deprivation resulted in an increased epithelial mesenchymal transition (EMT), leading to intestinal permeability. Under nutrient deprivation, IL-17E/25, which is secreted by IL-1β, demolished the intestinal epithelial barrier. Our results suggest that an upregulation of autophagy maintains the intestinal barrier by suppressing the activation of NLRP3 inflammasomes and the release of their products, including pro-inflammatory cytokines IL-1β and IL-17E/25, under nutrient deprivation.

Autophagy in the uterine vessel microenvironment: Balancing vasoactive factors

  • Lim, Hyunjung Jade
    • Clinical and Experimental Reproductive Medicine
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    • 제47권4호
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    • pp.263-268
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    • 2020
  • Autophagy, which has the literal meaning of self-eating, is a cellular catabolic process executed by arrays of conserved proteins in eukaryotes. Autophagy is dynamically ongoing at a basal level, presumably in all cells, and often carries out distinct functions depending on the cell type. Therefore, although a set of common genes and proteins is involved in this process, the outcome of autophagic activation or deficit requires scrutiny regarding how it affects cells in a specific pathophysiological context. The uterus is a complex organ that carries out multiple tasks under the influence of cyclic changes of ovarian steroid hormones. Several major populations of cells are present in the uterus, and the interactions among them drive complex physiological tasks. Mouse models with autophagic deficits in the uterus are very limited, but provide an initial glimpse at how autophagy plays a distinct role in different uterine tissues. Herein, we review recent research findings on the role of autophagy in the uterine mesenchyme in mouse models.