• Molecules and Cells
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• 제26권2호
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• pp.165-170
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• 2008

Procaspase-8 is activated by forming a death-inducing signaling complex (DISC) with the Fas-associated death domain (FADD) and the Fas receptor, but the mechanism of its activation is not well understood. Procaspase-8 devoid of the death effector domain at its N-terminus (${\Delta}nprocaspase-8$) was reported to be activated by kosmotropic salts, but it has not been induced to form a DISC in vitro because it cannot interact with FADD. Here, we report the production of full-length procaspase-8 and show that it is activated by adding the Fas death domain (Fas-DD) and the FADD forming the cytoplasmic part of the DISC (cDISC). Furthermore, mutations known to affect DISC formation in vivo were shown to have the same effect on procaspase-8 activation in vitro. An antibody that induces Fas-DD association enhanced procaspase-8 activation, suggesting that the Fas ligand is not required for low-level activation of procaspase-8, but that Fas receptor clustering is needed for high-level activation of procaspase-8 leading to cell death. In vitro activation of procaspase-8 by forming a cDISC will be invaluable for investigating activation of ligand-mediated apoptosis and the numerous interactions affecting procaspase-8 activation.

• 생명과학회지
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• 제31권10호
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• pp.954-959
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• 2021

세포 사멸은 항상성을 유지하기 위해 세포군을 조절하는 중요한 메커니즘이며 시스테인 단백질분해효소 중 하나인 카스파제는 세포 사멸 경로의 중요한 중재자이다. Caspase-8은 세포외 자극에 의해 시작되는 외인성 세포자멸 경로의 개시자 카스파제이다. Caspase-8에는 보존된 도메인인 N-말단의 두개의 죽음 이펙터 도메인(DED)과 C-말단의 2개의 촉매 도메인을 가지며, 이는 이러한 외인성 세포자멸 경로에 중요하게 작용한다. 외인성 세포멸사 경로에서, TNF 슈퍼패밀리인 죽음 수용체는 세포 외부로부터의 죽음 수용체 특이적 리간드의 결합에 의해 활성화된다. 활성화된 죽음 수용체가 어댑터 단백질인 Fas-associated death domain 단백질(FADD)을 모집한 후, 죽음 수용체와 FADD의 죽음 도메인(DD)이 서로 결합하고 죽음 수용체와 결합한 FADD가 caspase-8의 전구체 형태인 procaspase-8을 모집한다. FADD와 procaspase-8의 죽음 이펙터 도메인은 서로 결합하고 FADD에 결합된 procaspase-8은 prodomain의 절단에 의해 활성화된다. 이 죽음 수용체-FADD-caspase-8 복합체는 세포사멸 유도 신호복합체(DISC)라고 한다. 세포 FLICE 억제 단백질(c-FLIPs)은 세포사멸을 억제하는 역할과 촉진하는 역할을 모두 수행하여 caspase-8의 활성화를 조절하고 caspase-8 활성화는 caspase-3와 같은 작동자 카스파제를 활성화를 시킨다. 마지막으로 활성화된 작동자 카스파제는 DNA 분해, 핵 응축, 세포막 수포 및 카스파제 기질의 단백질 분해에 작용하여 세포사멸을 완료한다.

• 통합자연과학논문집
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• 제7권1호
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• pp.25-38
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• 2014

Amyloid-${\beta}$-peptide ($A{\beta}$) is important in the pathogenesis of Alzheimer's disease (AD). Calpain ($Ca^{2+}$-dependent protease) and caspase-8 (the initiating caspase for the extrinsic, receptor-mediated apoptosis pathway) have been implicated in $AD/A{\beta}$ toxicity. We found that $A{\beta}$ promoted degradation of calpastatin (the specific endogenous calpain inhibitor); calpastatin degradation was prevented by inhibitors of either calpain or caspase-8. The results implied a cross-talk between the two proteases and suggested that one protease was responsible for the activity of the other one. In neuron-like differentiated PC12 cells, calpain promotes active caspase-8 formation from procaspase-8 via the $A{\beta}$ and CD95 pathways, along with degradation of the procaspase-8 processing inhibitor caspase-8 (FLICE)-like inhibitory protein, short isoform (FLIPS). Inhibition of calpain (by pharmacological inhibitors and by overexpression of calpastatin) prevents the cleavage of procaspase-8 to mature, active caspase-8, and inhibits FLIPS degradation in the $A{\beta}$-treated and CD95-triggered cells. Increased cellular Ca2+ per se results in calpain activation but does not lead to caspase-8 activation or FLIPS degradation. The results suggest that procaspase-8 and FLIPS association with cell membrane receptor complexes is required for calpain-induced caspase-8 activation. The results presented here add to the understanding of the roles of calpain, caspase- 8, and CD95 pathway in $AD/A{\beta}$ toxicity. Calpain-promoted activation of caspase-8 may have implications for other types of CD95-induced cell damage, and for nonapoptotic functions of caspase-8. Inhibition of calpain may be useful for modulating certain caspase-8-dependent processes.

• 대한한의학방제학회지
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• 제14권2호
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• pp.21-32
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• 2006

The purpose of this study was to investigate the effect of Imyosan on apoptosis in human colorectal cancer HCT116 cells. Phellodendron amurense Rupr. and Atratylodes lancea D.C. compose Imyosan. First of all, to study the cytotoxic effect of methanol extract of Imyosan (IMS-MeOH) on HCT116 cells, the cells were treated with various concentrations of IMS-MeOH and then cell viability was determined by XTT reduction method. IMS-MeOH reduced viability of HCT116 cells in a dose and time-dependent manner. To confirm the induction of apoptosis, the c1eavage of poly ADP-ribose polymerase (PARP), a substrate for caspase-3 and a typical sign of apoptosis, and the activation of caspase-3, procaspase-8 and procaspase-9 were examined by western blot analysis. IMS-MeOH decreased procaspase-3, procaspase-8 and procaspase-9 levels in a dose-dependent manner and induced the clevage of PARP. IMS-MeOH triggered the mitochondrial apoptotic signaling by increasing the release of cytochrome c from mitochondria to cytosol. Furthermore, IMS-MeOH also downregulated the anti-apoptotic Bcl-2 and upregulated the pro-apoptotic-Bax. Therefore, these results suggest that IMS-MeOH induced HCT1l6 cell death through the mitochondrial pathway. To explore whether the activities of caspases was required for induction of apoptosis by IMS-MeOH, caspase-3, -8, -9 activity measured by using substrates, respectively. IMS-MeOH increased caspase-3, -8, -9 activity. Co-treatment with inhibitors of caspase-3, -8, -9 and IMS-MeOH significantly blocked IMS-MeOH-triggered apoptosis in HCT1l6 cells. These results suggest that IMS-MeOH induces caspases-mediated apoptosis.

• 대한한의학방제학회지
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• 제15권2호
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• pp.127-137
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• 2007

The purpose of this study was to investigate the effect of Yong-dam-sa-gan-tang (YST) on apoptosis in HepG2 cells, First of all. to study the cytotoxic effect of methanol extract of YST on HepG2 cells, the cells were treated with various concentrations of YST and then cell viability was determined by XTT reduction method and trypan blue exclusion assay. YST reduced proliferation of HepG2 cells in a dose-dependent manner. To confirm the induction of apoptosis, HepG2 cells were treated with various concentrations of YST. The cleavage of poly AD P-ribose polymerase (P ARP), a substrate for caspase-3 and a typical sign of apoptosis, and the activation of caspase-3, procaspase-8 and procaspase-8 were examined by western blot analysis. YST decreased procaspase-3, procaspase-8 and procaspase-9 levels in a dose-dependent manner and induced the clevage of PARP. YST triggered the mitochondrial apoptotic signaling by increasing the release of cytochrome c from mitochondria to cytosol. Furthermore, YST also downregulated the anti-apoptotic Bcl-2 and upregulated the pro-apoptotic-Bax. Therefore, this result suggest that YST induced HepG2 cell death through the mitochondrial pathway. Sustained activation of the Ras/Raf/MEK/ERK cascade in cells results in a cell cycle arrest and has been implicated in the differentiation of certain cell types, in many cases acting to promote differentiation. YST decreased the activation of Ras/Raf/MEK/ERK cascade in a dose-dependent manner. These results suggest that YST is potentially useful as a chemo-therapeutic agent in HepG2.

• 생명과학회지
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• 제16권1호
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• pp.30-36
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• 2006

호중구의 세포사멸은 자연적으로 일어나지만 여러 외부자극에 의한 신호의 전달에 의하여 증가하거나 지연된다. 본 연구에서는 항암, 항생제로 개발된 프레닐 페놀계인 ascochlorin의 유도체 중에서 백혈구 암의 세포사멸을 유도하는 4-O-methyl-ascochlorin (MAC)이 호중구의 자연 세포사멸 및 지연되는 세포사멸에 어떠한 영향을 미치는가와 그 작용기작을 연구하였다. 호중구의 세포사멸은 사람 말초 혈액으로부터 분리하여 세포 배양 시간에 따라 형태 변화, annexin-V/propidium iodide의 염색, 및 DNA 전기영동 등으로 조사하였다. MAC는 농도 및 시간 의존 형으로 호중구의 세포사멸을 증가시켰다. 그러나 granulocyte macrophage-colony stimulating factor나 lipopolysaccharide 등에 의한 세포사멸의 지연은 MAC에 의하여 부분적으로 억제되었다. MAC에 의한 세포사멸의 유도는 pancaspase, caspase-8 및 caspase-3 억제제인 zVAD-fmk. zIETD-fmk, 및 zDEVD-fmk에 의하여 억제되었으며 procaspase-8과 procaspase-3의 단백질 양도 MAC로 처리한 호중구에서 현저히 감소하였다. 미토콘드리아 막 투과성은 MAC에 의하여 현저히 감소하였으나 zVAD-fmk에 의하여 완전히 봉쇄되지 못하였다. 이들 결과 들은 MAC에 의한 호중구 세포사멸의 증가는 caspase-8 및 caspase-3의 활성을 통하여 일어나지만 미토콘드리아의 막성분에는 영향이 없다는 것을 제시하고 있다.

• 동의생리병리학회지
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• 제17권2호
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• pp.293-296
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• 2003

Prunellae Spica is a flower petal of Prunella vulgaris var. lilacina used for treatment of lymphoma, breast cancer, hepatitis and pathological fluid related diseases in oriental medicine. We tried to evaluate the mechanism of Prunellae Spica in the treatment of cancer. The ethyl acetate layer of Prunellae Spica showed a good cytotoxicity on U937 cells with IC50 of 8 ug/ml. It induced apoptosis in U937 dose-dependently by cell cycle analysis following PI staining. We also confirmed it induced DNA fragmentation in U937 cells from the concentration of 10 ug/ml. From western blot assay we observed the ethyl acetate layer of Prunellae Spica downregulated procaspase-3 and cleaved PARP in a dose dependent manner, whereas it didn't affect bax and bcl-2. Taken together, these results indicate the ethyl acetate layer of Prunellae Spica can induce apoptosis in U937 cells suggesting it can be potently applied to cancer.

• 동의생리병리학회지
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• 제19권3호
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• pp.677-683
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• 2005

The aim of this study was to investigate the apoptotic effect and its mechanism on Radix Aconiti (RA) extract in HL-60 human leukemia cell line. RA extract induced apoptosis as confirmed by discontinuous fragmentation of DNA. To clarify the mechanisms on RA extract-induced apoptosis, we examined the caspase-3, -8 enzyme activity and protein levels including Fas, FasL in HL-60 cells. Treatment with RA extracts resulted in the increase of caspase-3 enzyme activity in a time and dose-dependent manners, which was accompanied by the cleavage of poly-(ADP-ribose) polymerase (PARP). This activation of caspase-3 enzyme resulted from cleavage of procaspase-8, which was followed by increases of FasL, Fas protein expression in RA extracts-treated HL-60 cells. In conclusion, RA extract induced apoptosis of HL-60 human leukemia cell line. This results suggest that the apoptotic mechanisms of RA extract on HL-60 cells involved in FasL, Fas activation, procaspase-8 cleavage, activation of caspase-3 and cleavage of PARP. Collectively, these results suggest that RA may be a valuable agent as a anti-cancer drug.

• 대한약학회:학술대회논문집
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• 대한약학회 2003년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.2-2
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• pp.107.1-107.1
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• 2003

20-O-(${\beta}$-D-Glucopyranosyl)-20(S)-protopanaxadiol (IH901), an intestinal bacterial metabolite of ginseng saponins formed from ginsenosides Rb1, Rb2 and Rc, is suggested to be a potential chemopreventive agent. Here we show that IH901 induces apoptosis in human hepatoblastoma HepG2 cells. IH901 led to an early activation of procaspase-3 (6 h posttreatment), and the activation of caspase-8 became evident only later (18 h posttreatment). Caspase activation was a necessary requirement for apoptosis because caspase inhibitors significantly inhibited cell death by IH901. (omitted)

• 생명과학회지
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• 제27권3호
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• pp.267-274
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• 2017

본 연구는 말기 신부전 환자의 체내에서 증가되는 시안산이 신경학적 합병증의 원인으로 작용하는지 알아보고자 시안산 처리에 따른 신경아교종 세포인 C6 세포의 변화를 관찰하였다. 또한, 시안산에 의해 발현되는 세포자멸사 관련 인자를 알아보기 위하여 western blot 및 유전자 발현의 변화를 검색하기 위하여 cDNA 유전자 미세배열분석을 하였다. 시안산의 처리 농도가 0, 1, 5, 10, 20, 40 mM 증가할수록 신경아교종 세포의 생존율이 유의하게 감소하였고 세포자멸사에 주된 역할을 하는 caspase-8는 증가되었고 procaspase-3는 감소하였다. 그러나 caspase-8에 의해 활성화되는 Bax 단백질은 시안산의 처리 농도가 증가할수록 caspase-8의 증가에도 감소하였고, 세포자멸사를 조절하는 단백질인 Bcl-2와 IAP은 명확히 확인할 수 없었다. cDNA 유전자 미세배열 분석 결과, 총 1,099 종의 유전자 중에서 934 개의 유전자가 감소하였고 증가된 것은 165 개였다. 세포자멸사 관련 유전자에서도 감소한 것은 16 개였고, 증가된 6 개 유전자 가운데 heat shock 70 kD protein 1A가 현저한 증가를 나타내었다. 이상의 결과로 보아, 시안산은 신경아교종 세포에서 caspase-8 및 caspase-3와 관련된 세포자멸사를 유발시키며, 신경아교종 세포의 유전자들의 발현을 감소시키는 것으로 생각된다. 따라서 체내에서 증가된 시안산이 신경아교종 세포에 영향을 미쳐 말기 신부전 환자의 뇌병증에도 영향을 주는 것이라 생각된다.