共查询到20条相似文献,搜索用时 546 毫秒
1.
Quinn P. Peterson David R. Goode Diana C. West Joy J.Y. Lee 《Journal of molecular biology》2009,388(1):144-50
The direct induction of apoptosis has emerged as a powerful anticancer strategy, and small molecules that either inhibit or activate certain proteins in the apoptotic pathway have great potential as novel chemotherapeutic agents. Central to apoptosis is the activation of the zymogen procaspase-3 to caspase-3. Caspase-3 is the key “executioner” caspase, catalyzing the hydrolysis of a multitude of protein substrates within the cell. Interestingly, procaspase-3 levels are often elevated in cancer cells, suggesting a compound that directly stimulates the activation of procaspase-3 to caspase-3 could selectively induce apoptosis in cancer cells. We recently reported the discovery of a compound, PAC-1, which enhances procaspase-3 activity in vitro and induces apoptotic death in cancer cells in culture and in mouse xenograft models. Described herein is the mechanism by which PAC-1 activates procaspase-3 in vitro. We show that zinc inhibits the enzymatic activity of procaspase-3 and that PAC-1 strongly activates procaspase-3 in buffers that contain zinc. PAC-1 and zinc form a tight complex with one another, with a dissociation constant of approximately 42 nM. The combined data indicate that PAC-1 activates procaspase-3 in vitro by sequestering inhibitory zinc ions, thus allowing procaspase-3 to autoactivate itself to caspase-3. The small-molecule-mediated activation of procaspases has great therapeutic potential and thus this discovery of the in vitro mechanism of action of PAC-1 is critical to the development and optimization of other procaspase-activating compounds. 相似文献
2.
Mónica Sancho Anna Gortat Andrés E. Herrera Vicente Andreu-Fernández Elisabetta Ferraro Francesco Cecconi Mar Orzáez Enrique Pérez-Payá 《PloS one》2014,9(1)
Background
Apaf1 (apoptotic protease activating factor 1) is the central component of the apoptosome, a multiprotein complex that activates procaspase-9 after cytochrome c release from the mitochondria in the intrinsic pathway of apoptosis. Other cellular roles, including a pro-survival role, have also been described for Apaf1, while the relative contribution of each function to cell death, but also to cell homeostatic conditions, remain to be clarified.Methodology and Principal Findings
Here we examined the response to apoptosis induction of available embryonic fibroblasts from Apaf1 knockout mice (MEFS KO Apaf1). In the absence of Apaf1, cells showed mitochondria with an altered morphology that affects cytochrome c release and basal metabolic status.Conclusions
We analysed mitochondrial features and cell death response to etoposide and ABT-737 in two different Apaf1-deficient MEFS, which differ in the immortalisation protocol. Unexpectedly, MEFS KO Apaf1 immortalised with the SV40 antigen (SV40IM-MEFS Apaf1) and those which spontaneously immortalised (SIM-MEFS Apaf1) respond differently to apoptotic stimuli, but both presented relevant differences at the mitochondria when compared to MEFS WT, indicating a role for Apaf1 at the mitochondria. 相似文献3.
Stephen P. Burke Lucinda Smith Jeffrey B. Smith 《The Journal of biological chemistry》2010,285(39):30061-30068
Although early studies of inhibitor of apoptosis proteins (IAPs) suggested that cIAP1 directly binds and inhibits caspases similarly to X-linked IAP (XIAP), a recent one found that micromolar concentrations of cIAP1 only weakly inhibit caspase-3, -7, or -9. Here, we show that cIAP1 specifically and cooperatively blocks the cytochrome c-dependent apoptosome in vitro. Hence, cIAP1 prevented the activation of procaspase-3 but had no effect on the processing of procaspase-9 or the activity of prior activated caspase-3. Like cIAP1, XIAP had no effect on procaspase-9 processing and was a more potent inhibitor of procaspase-3 activation than of already activated caspase-3 activity. Inhibition of procaspase-3 activation depended on BIR2 and BIR3 of cIAP1 and was independent of BIR1, RING, CARD, and UBA domains. Smac prevented cIAP1 from inhibiting procaspase-3 activation and reversed the inhibition by prior addition of cIAP1. A procaspase-9 mutant (D315A) that cannot produce the p12 subunit was resistant to inhibition by cIAP1. Therefore, the N-terminal Ala-Thr-Pro-Phe motif of the p12 subunit of the caspase-9 apoptosome facilitates apoptosome blockade. Consequently, cIAP1 cooperatively interacts with oligomerized processed caspase-9 in the apoptosome and blocks procaspase-3 activation. 相似文献
4.
《Free radical biology & medicine》2011,50(12):1925-1936
Low levels of reactive oxygen species (ROS) can function as redox-active signaling messengers, whereas high levels of ROS induce cellular damage. Menadione generates ROS through redox cycling, and high concentrations trigger cell death. Previous work suggests that menadione triggers cytochrome c release from mitochondria, whereas other studies implicate the activation of the mitochondrial permeability transition pore as the mediator of cell death. We investigated menadione-induced cell death in genetically modified cells lacking specific death-associated proteins. In cardiomyocytes, oxidant stress was assessed using the redox sensor RoGFP, expressed in the cytosol or the mitochondrial matrix. Menadione elicited rapid oxidation in both compartments, whereas it decreased mitochondrial potential and triggered cytochrome c redistribution to the cytosol. Cell death was attenuated by N-acetylcysteine and exogenous glutathione or by overexpression of cytosolic or mitochondria-targeted catalase. By contrast, no protection was observed in cells overexpressing Cu,Zn-SOD or Mn-SOD. Overexpression of antiapoptotic Bcl-XL protected against staurosporine-induced cell death, but it failed to confer protection against menadione. Genetic deletion of Bax and Bak, cytochrome c, cyclophilin D, or caspase-9 conferred no protection against menadione-induced cell death. However, cells lacking PARP-1 showed a significant decrease in menadione-induced cell death. Thus, menadione induces cell death through the generation of oxidant stress in multiple subcellular compartments, yet cytochrome c, Bax/Bak, caspase-9, and cyclophilin D are dispensable for cell death in this model. These studies suggest that multiple redundant cell death pathways are activated by menadione, but that PARP plays an essential role in mediating each of them. 相似文献
5.
HeeWon Kang Baek-Soo Han Su-Jeong Kim Young J. Oh 《Apoptosis : an international journal on programmed cell death》2012,17(5):449-462
The evidence implicating a mode of cell death that either favors or argues against caspase-dependent apoptosis is available
in studies that used experimental models of Parkinson’s disease. We sought to investigate the mechanisms by which release
of cytochrome c is not linked to caspase activation during rotenone-induced dopaminergic (DA) neurodegeneration. Unlike caspase activation
in 6-hydroxydopamine-treated cells, both MN9D DA neuronal cells and primary cultures of mesencephalic neurons showed no obvious
signs of caspase activation upon exposure to rotenone. We found that intracellular levels of ATP significantly decreased at
the early phase of neurodegeneration (<~24 h) and therefore external addition of ATP to the lysates obtained at this stage
reconstituted caspase-3 activity. At a later phase of cell death (>~24 h), both decreased levels of ATP and procaspase-9 contributed
to the lack of caspase-3 activation. Under this condition, calpain and the proteasome system were responsible for the degradation
of procaspase-9. Consequently, external addition of ATP and procaspase-9 to the lysates harvested at the later phase was required
for activation of caspase-3. Similarly, caspase-3 activity was also reconstituted in the lysates harvested from cells co-treated
with inhibitors of these proteases and incubated in the presence of external ATP. Taken together, our findings provided a
sequential mechanism underlying how DA neurons may undergo caspase-independent cell death, even in the presence of cytoplasmic
cytochrome c following inhibition of mitochondrial complex I. 相似文献
6.
Y-J Hsieh K-Y Chien S-Y Lin S Sabu R-M Hsu L-M Chi P-C Lyu J-S Yu 《Cell death & disease》2012,3(7):e347
Diverse death phenotypes of cancer cells can be induced by Photofrin-mediated photodynamic therapy (PDT), which has a decisive role in eliciting a tumor-specific immunity for long-term tumor control. However, the mechanism(s) underlying this diversity remain elusive. Caspase-3 is a critical factor in determining cell death phenotypes in many physiological settings. Here, we report that Photofrin-PDT can modify and inactivate procaspase-3 in cancer cells. In cells exposed to an external apoptotic trigger, high-dose Photofrin-PDT pretreatment blocked the proteolytic activation of procaspase-3 by its upstream caspase. We generated and purified recombinant procaspase-3-D3A (a mutant without autolysis/autoactivation activity) to explore the underlying mechanism(s). Photofrin could bind directly to procaspase-3-D3A, and Photofrin-PDT-triggered inactivation and modification of procaspase-3-D3A was seen in vitro. Mass spectrometry-based quantitative analysis for post-translational modifications using both 16O/18O- and 14N/15N-labeling strategies revealed that Photofrin-PDT triggered a significant oxidation of procaspase-3-D3A (mainly on Met-27, -39 and -44) in a Photofrin dose-dependent manner, whereas the active site Cys-163 remained largely unmodified. Site-directed mutagenesis experiments further showed that Met-44 has an important role in procaspase-3 activation. Collectively, our results reveal that Met oxidation is a novel mechanism for the Photofrin-PDT-mediated inactivation of procaspase-3, potentially explaining at least some of the complicated cell death phenotypes triggered by PDT. 相似文献
7.
To gain further insight into yeast acetic acid-induced programmed cell death (AA-PCD) we analyzed the effects of the antioxidant N-acetyl-l-cysteine (NAC) on cell viability, hydrogen peroxide (H2O2) production, DNA fragmentation, cytochrome c (cyt c) release and caspase-like activation in wild type (wt) and metacaspase and/or cyt c-lacking cells. We found that NAC prevents AA-PCD in wt cells, by scavenging H2O2 and by inhibiting both cyt c release and caspase-like activation. This shows the occurrence of a reactive oxygen species (ROS)-dependent AA-PCD. Contrarily no NAC dependent change in AA-PCD of mutant cells was detectable, showing that a ROS-independent AA-PCD can also occur. 相似文献
8.
Yuanhong Liao Jianya Ling Guoying Zhang Fengjun Liu Shengce Tao Zeguang Han Saijuan Chen Zhu Chen Huangying Le 《Cell cycle (Georgetown, Tex.)》2015,14(5):761-771
Cordycepin, an adenosine analog derived from Cordyceps militaris has been shown to exert anti-tumor activity in many ways. However, the mechanisms by which cordycepin contributes to the anti-tumor still obscure. Here our present work showed that cordycepin inhibits cell growth in NB-4 and U937 cells by inducing apoptosis. Further study showed that cordycepin increases the expression of p53 which promotes the release of cytochrome c from mitochondria to the cytosol. The released cytochrome c can then activate caspase-9 and trigger intrinsic apoptosis. Cordycepin also blocks MAPK pathway by inhibiting the phosphorylation of ERK1/2, and thus sensitizes the apoptosis. In addition, our results showed that cordycepin inhibits the expression of cyclin A2, cyclin E, and CDK2, which leads to the accumulation of cells in S-phase. Moreover, our study showed that cordycepin induces DNA damage and causes degradation of Cdc25A, suggesting that cordycepin-induced S-phase arrest involves activation of Chk2-Cdc25A pathway. In conclusion, cordycepin-induced DNA damage initiates cell cycle arrest and apoptosis which leads to the growth inhibition of NB-4 and U937 cells. 相似文献
9.
Adam J. Kole Elizabeth R.W. Knight Mohanish Deshmukh 《Journal of visualized experiments : JoVE》2011,(52)
Apoptosis, or programmed cell death, is a conserved and highly regulated pathway by which cells die1. Apoptosis can be triggered when cells encounter a wide range of cytotoxic stresses. These insults initiate signaling cascades that ultimately cause the release of cytochrome c from the mitochondrial intermembrane space to the cytoplasm2. The release of cytochrome c from mitochondria is a key event that triggers the rapid activation of caspases, the key cellular proteases which ultimately execute cell death3-4.The pathway of apoptosis is regulated at points upstream and downstream of cytochrome c release from mitochondria5. In order to study the post-mitochondrial regulation of caspase activation, many investigators have turned to direct cytoplasmic microinjection of holocytochrome c (heme-attached) protein into cells6-9. Cytochrome c is normally localized to the mitochondria where attachment of a heme group is necessary to enable it to activate apoptosis10-11. Therefore, to directly activate caspases, it is necessary to inject the holocytochrome c protein instead of its cDNA, because while the expression of cytochrome c from cDNA constructs will result in mitochondrial targeting and heme attachment, it will be sequestered from cytosolic caspases. Thus, the direct cytosolic microinjection of purified heme-attached cytochrome c protein is a useful tool to mimic mitochondrial cytochrome c release and apoptosis without the use of toxic insults which cause cellular and mitochondrial damage.In this article, we describe a method for the microinjection of cytochrome c protein into cells, using mouse embryonic fibroblasts (MEFs) and primary sympathetic neurons as examples. While this protocol focuses on the injection of cytochrome c for investigations of apoptosis, the techniques shown here can also be easily adapted for microinjection of other proteins of interest. 相似文献
10.
Nicoletta Guaragnella Antonella Bobba Ersilia Marra Sergio Giannattasio 《FEBS letters》2010,584(1):224-228
To investigate the role of cytochrome c (cyt c) release in yeast acetic acid-induced programmed cell death (AA-PCD), wild type (wt) and cells lacking metacaspase (Δyca1), cytochrome c (Δcyc1,7) and both (Δcyc1,7Δyca1) were compared for AA-PCD occurrence, hydrogen peroxide (H2O2) production and caspase activity. AA-PCD occurs in Δcyc1,7 and Δcyc1,7Δyca1 cells slower than in wt, but similar to that in Δyca1 cells, in which no cytochrome c release occurs. Both H2O2 production and caspase activation occur in these cells with early and extra-activation in Δcyc1,7 cells. We conclude that alternative death pathways can be activated in yeast AA-PCD, one dependent on cyt c release, which requires YCA1, and the other(s) independent on it. 相似文献
11.
Madhavi Gorla Naresh Babu V. Sepuri 《Apoptosis : an international journal on programmed cell death》2014,19(1):259-268
In response to apoptotic stimuli, cytochrome c, an inter-membrane space protein is released from mitochondria to activate the cascade of caspases that leads to apoptosis. Recent evidence suggests that cytochrome c interacts with tRNA in the cytoplasm and this interaction was shown to inhibit the caspase mediated apoptotic process. Interestingly, cytochrome c does not contain any putative RNA binding domain. In this report, we sought to define the structural component of cytochrome c that is involved in binding of tRNA. By using gel mobility shift assays, we show that holocytochrome c can interact with tRNA but not apocytochrome c that lacks the heme domain suggesting that heme is essential for the interaction of cytochrome c to tRNA. In addition, using in vitro cross linking and circular dichroism spectroscopic studies, we show that cytochrome c can undergo heme mediated oligomerization. Prevention of heme mediated oligomerization of cytochrome c by potassium ferricyanide treatment prevents the binding of tRNA and promotes caspase activation. Our studies provide a novel regulation of apoptosis by heme dependent tRNA interaction to cytochrome c. 相似文献
12.
Hongyan Zhang Wenxia WangHeng Yin Xiaoming Zhao Yuguang Du 《Carbohydrate polymers》2012,87(3):2270-2278
Oligochitosan has been proved to trigger plant cell death. To gain some insights into the mechanisms of oligochitosan-induced cell death, the nature of oligochitosan-induced cell death and the role of calcium (Ca2+), nitric oxide (NO) and hydrogen peroxide (H2O2) were studied in tobacco suspension cells. Oligochitosan-induced cell death occurred in cytoplasmic shrinkage, phosphatidylserine externalization, chromatin condensation, TUNEL-positive nuclei, cytochrome c release and induction of programmed cell death (PCD)-related gene hsr203J, suggesting the activation of PCD pathway. Pretreatment cells with cyclosporin A, resulted in reducing oligochitosan-induced cytochrome c release and cell death, indicating oligochitosan-induced PCD was mediated by cytochrome c. In the early stage, cells undergoing PCD showed an immediate burst in free cytosolic Ca2+ ([Ca2+]cyt) elevation, NO and H2O2 production. Further study showed that these three signals were involved in oligochitosan-induced PCD, while Ca2+ and NO played a negative role in this process by modulating cytochrome c release. 相似文献
13.
Arti Parihar Mordhwaj S. Parihar Rafal Nazarewicz Pedram Ghafourifar 《Biochimica et Biophysica Acta (BBA)/General Subjects》2010
Background
Ceramides are intracellular lipid mediator implicated in various cellular responses, including oxidative stress and programmed cell death. Studies demonstrated strong links between ceramide and the mitochondria in the regulation of apoptosis. However, the mechanism of apoptosis induced by ceramides is not fully understood. The present study delineates importance of the redox state of cytochrome c for release of cytochrome c and apoptosis of human mammary adenocarcinoma MCF-7 and MDA-MB-231 cells induced by ceramides.Methods
The study uses MCF-7 and MDA-MB-231 cells, isolated mitochondria, submitochondrial particles, and oxidized and reduced cytochrome c. Methods used include flow cytometry, immunoblotting, spectroscopy, and respirometry.Results
We show that ceramides induce mitochondrial oxidative stress and release of cytochrome c from the mitochondria of these cells. Our findings show that ceramides react with oxidized cytochrome c whereas reduced cytochrome c does not react with ceramides. We also show that oxidized cytochrome c reacted with ceramides exerts lower reducibility and function to support mitochondrial respiration. Furthermore, our data show that glutathione protects cytochrome c of reacting with ceramides by increasing the reduced state of cytochrome c.Conclusions
Ceramides induce oxidative stress and apoptosis in human mammary adenocarcinoma cells by interacting with oxidized cytochrome c leading to the release of cytochrome c from the mitochondria. Our findings suggest a novel mechanism for protective role of glutathione.General significance
Our study suggests that the redox state of cytochrome c is important in oxidative stress and apoptosis induced by ceramides. 相似文献14.
Previously, we demonstrated that both 150 mM KCl and alkaline pH inhibit cytochrome c-mediated activation of procaspase-3 in a unique manner. To determine the mechanism of inhibition, we analyzed the effect of KCl and alkaline pH on the formation of apoptosomes (a large complex consisting of cytochrome c, Apaf-1, and procaspase-9/caspase-9) in vitro. Our results suggest that an initial 700-kDa apoptosome matures through a 1.4-MDa intermediate before a 700-kDa apoptosome is reformed and procaspase-3 is activated. We further demonstrate that 150 mM KCl interferes with the conversion of the initial 700-kDa apoptosome to the 1.4-MDa intermediate, while alkaline pH "traps" the apoptosome in the 1.4-MDa intermediate. Analysis of the cleaved state of procaspase-9 and procaspase-3 suggests that the 1.4-MDa intermediate may be required for cleavage of procaspase-9. Consistent with these results, in vivo data suggest that blocking acidification during the induction of apoptosis inhibits activation of procaspase-3. On the basis of these results, we propose a model of apoptosome maturation. caspase; pH; potassium; apoptosis 相似文献
15.
Julie Garibal Émilie Hollville Benjamin Renouf Cécile Tétaud Joëlle Wiels 《Cellular signalling》2010,22(3):467-475
Verotoxin (VT-1) is a cytotoxin, produced by Shigella dysenteriae type 1 or by Shiga toxin-producing Escherichia coli, which binds specifically to globotriaosylceramide (Gb3). This glycosphingolipid is a B cell differentiation antigen (Gb3/CD77) strongly expressed on Burkitt's lymphoma cells. We have previously shown that, in these cells, VT-1 induces apoptosis via a caspase- and mitochondria-dependent pathway. In this report, we provide new insights into this signal transduction pathway. First, we demonstrate that VT-1-induced apoptosis requires degradation of the caspase-8 inhibitory molecule c-FLIPL and that this degradation occurs through the ubiquitin–proteasome pathway. Furthermore, we show that mitochondrial activation is mainly due to i) cleavage and activation of the pro-apoptotic Bcl-2 family member Bid by caspase-8 and ii) Bax relocalization to mitochondrial membranes which lead to cytochrome c release. However, tBid is not involved in Bax relocalization, and relocalization is most likely controlled by the extent of Bax phosphorylation: in non-treated BL cells, p38 MAPK participates in the retention of Bax in the cytoplasm in an inactive form whereas in VT-1 treated cells, protein phosphatase 2A is activated and induces Bax relocalization to mitochondria. 相似文献
16.
Shiva Akbari-Birgani Saman Hosseinkhani Sepideh Mollamohamadi Hossein Baharvand 《The Journal of biological chemistry》2014,289(24):16905-16913
Differentiation is an inseparable process of development in multicellular organisms. Mouse embryonic stem cells (mESCs) represent a valuable research tool to conduct in vitro studies of cell differentiation. Apoptosis as a well known cell death mechanism shows some common features with cell differentiation, which has caused a number of ambiguities in the field. The research question here is how cells could differentiate these two processes from each other. We have investigated the role of the mitochondrial apoptotic pathway and cell energy level during differentiation of mESCs into the cardiomyocytes and their apoptosis. p53 expression, cytochrome c release, apoptosome formation, and caspase-3/7 activation are observed upon induction of both apoptosis and differentiation. However, remarkable differences are detected in time of cytochrome c appearance, apoptosome formation, and caspase activity upon induction of both processes. In apoptosis, apoptosome formation and caspase activity were observed rapidly following the cytochrome c release. Unlike apoptosis, the release of cytochrome c upon differentiation took more time, and the maximum caspase activity was also postponed for 24 h. This delay suggests that there is a regulatory mechanism during differentiation of mESCs into cardiomyocytes. The highest ATP content of cells was observed immediately after cytochrome c release 6 h after apoptosis induction and then decreased, but it was gradually increased up to 48 h after differentiation. These observations suggest that a delay in the release of cytochrome c or delay in ATP increase attenuate apoptosome formation, and caspase activation thereby discriminates apoptosis from differentiation in mESCs. 相似文献
17.
Thomas F. Reubold Sabine Wohlgemuth Susanne Eschenburg 《The Journal of biological chemistry》2009,284(47):32717-32724
The cytosolic adaptor protein Apaf-1 is a key player in the intrinsic pathway of apoptosis. Binding of mitochondrially released cytochrome c and of dATP or ATP to Apaf-1 induces the formation of the heptameric apoptosome complex, which in turn activates procaspase-9. We have re-investigated the chain of events leading from monomeric autoinhibited Apaf-1 to the functional apoptosome in vitro. We demonstrate that Apaf-1 does not require energy from nucleotide hydrolysis to eventually form the apoptosome. Despite a low intrinsic hydrolytic activity of the autoinhibited Apaf-1 monomer, nucleotide hydrolysis does not occur at any stage of the process. Rather, mere binding of ATP in concert with the binding of cytochrome c primes Apaf-1 for assembly. Contradicting the current view, there is no strict requirement for an adenine base in the nucleotide. On the basis of our results, we present a new model for the mechanism of apoptosome assembly. 相似文献
18.
Mitochondrial cytochrome c (cyt. c) release and caspase activation are often impaired in tumors with Bcl-2 overexpression or Bax and Bak-defective status. Direct triggering of cell death downstream of Bax and Bak is an attractive strategy to kill such cancers. Small molecule compounds capable of direct caspase activation appear to be the best mode for killing such tumors. However, there is no precise model to screen such compounds. The currently employed cell-free systems possess the inherent drawback of lacking cellular contents and organelles that operate in integrating cell death signaling. We have developed highly refined cell-based approaches to validate direct caspase activation in cancer cells. Using this approach, we show that PAC-1 (first procaspase-activating compound), the first direct activator of procaspases identified in a cell-free system, in fact requires mitochondrial cyt. c release for triggering caspase activation similar to other antitumor agents. It can induce significant caspase activation and cell death in the absence of Bax and Bak, and in cells overexpressing Bcl-2 and Bcl-xL. This study for the first time defines precise criteria for the validation of direct caspase-activating compounds using specialized cellular models that is expected to accelerate the discovery of potential direct caspase activators. 相似文献
19.
Short interfering RNA against the PDCD5 attenuates cell apoptosis and caspase-3 activity induced by Bax overexpression 总被引:5,自引:0,他引:5
Chen LN Wang Y Ma DL Chen YY 《Apoptosis : an international journal on programmed cell death》2006,11(1):101-111
The programmed cell death 5 (PDCD5) protein plays an important apoptosis-accelerating role in cells undergoing apoptosis.
Decreased expression of PDCD5 has been detected in various human carcinomas. Here we describe that one potent short interfering
RNA (siRNA) against the PDCD5 (siPDCD5) specifically inhibits the expression of PDCD5 at both the mRNA and protein level.
Cells with decreased PDCD5 expression displayed reduced sensitivity to an apoptotic stimulus induced by Bax overexpression
in HeLa, HEK293 and 293T cell lines. Furthermore, we also show that siPDCD5 inhibited both caspase-3 activity and procaspase-3
cleavage. Suppressed expression of PDCD5 attenuates the release of cytochrome c from mitochondria to cytosol induced by Bax overexpression. This phenomenon is accompanied by the reduced translocation of
Bax from the cytosol to mitochondria. MTT assay shows that targeted suppression of PDCD5 expression markedly promoted cell
proliferation in Hela and HEK293 cell lines. Our data suggests that PDCD5 may exert its effects through pathway of mitochondria
by modulating Bax translocation, cytochrome c release and caspase 3 activation directly or indirectly, and that decreased PDCD5 expression may be one of the mechanisms
by which tumor cells achieve resistance to apoptotic stimulus induced by anticancer drugs. 相似文献
20.
Three-dimensional structure of the apoptosome: implications for assembly, procaspase-9 binding, and activation 总被引:18,自引:0,他引:18
The apoptosome is an Apaf-1 cytochrome c complex that activates procaspase-9. The three-dimensional structure of the apoptosome has been determined at 27 A resolution, to reveal a wheel-like particle with 7-fold symmetry. Molecular modeling was used to identify the caspase recruitment and WD40 domains within the apoptosome and to infer likely positions of the CED4 homology motif and cytochrome c. This analysis suggests a plausible role for cytochrome c in apoptosome assembly. In a subsequent structure, a noncleavable mutant of procaspase-9 was localized to the central region of the apoptosome. This complex promotes the efficient activation of procaspase-3. Therefore, the cleavage of procaspase-9 is not required to form an active cell death complex. 相似文献