共查询到20条相似文献,搜索用时 125 毫秒
1.
Victor Umansky Frank Ratter Stefan Lampel Mariana Bucur Volker Schirrmacher Alexey Ushmorov 《Experimental cell research》2001,265(2):274
We have recently shown that nitric-oxide (NO)-induced apoptosis in Jurkat human leukemia cells requires degradation of mitochondria phospholipid cardiolipin, cytochrome c release, and activation of caspase-9 and caspase-3. Moreover, an inhibitor of lipid peroxidation, Trolox, suppressed apoptosis in Jurkat cells induced by NO donor glycerol trinitrate. Here we demonstrate that this antiapoptotic effect of Trolox occurred despite massive release of the mitochondrial protein cytochrome c into the cytosol and mitochondrial damage. Incubation with Trolox caused a profound reduction of intracellular ATP concentration in Jurkat cells treated by NO. Trolox prevented cardiolipin degradation and caused its accumulation in Jurkat cells. Furthermore, Trolox markedly downregulated the NO-mediated activation of caspase-9 and caspase-3. Caspase-9 is known to be activated by released cytochrome c and together with caspase-3 is considered the most proximal to mitochondria. Our results suggest that the targets of the antiapoptotic effect of Trolox are located downstream of the mitochondria and that caspase activation and subsequent apoptosis could be blocked even in the presence of cytochrome c released from the mitochondria. 相似文献
2.
Wang Z Liang R Huang GS Piao Y Zhang YQ Wang AQ Dong BX Feng JL Yang GR Guo Y 《Apoptosis : an international journal on programmed cell death》2006,11(10):1851-1860
Cathepsin D (cat D) reportedly plays an important role in certain apoptotic processes, the downstream pathways of which involve
release of cytochrome c (cyt c) from mitochondria and activation of the caspase cascade. Previous studies revealed that the B-cell lymphoma 2 (Bcl-2) family
members Bax or Bid play important roles in apoptotic signal transduction between cat D and mitochondria. Here, we show that
glucosamine sulfate (GS) inhibits the proliferation and induces apoptosis of human chronic myelogenous leukemia K562 cells
in vitro. GS interfered with the maturation of cat D. Activation of caspase-3, cleavage of poly-(ADP-ribose)-polymerase, release of
cyt c, and downregulation of Bcl-xL accompanied GS-induced apoptosis, and these processes were inhibited by the cat D inhibitor
pepstatin A. However, we did not detect any altered gene expression of Bcl-2, Bax, or Bid during apoptosis. Translocation
of cat D from the lysosome to the cytosol was observed in GS-treated K562 cells. These findings suggest that GS-induced K562
cell apoptosis involves the translocation of cat D from the lysosome to the cytosol. Furthermore, our findings suggest that
downregulation of Bcl-xL (but not Bcl-2, Bax, or Bid) connects cat D and the mitochondrial pathway, which causes the release
of cyt c and activation of the caspase cascade during GS-induced apoptosis of K562 cells. 相似文献
3.
Increase in the ratio of mitochondrial Bax/Bcl-XL induces Bax activation in human leukemic K562 cell line 总被引:5,自引:0,他引:5
Liu FT Goff LK Hao JH Newland AC Jia L 《Apoptosis : an international journal on programmed cell death》2004,9(3):377-384
The p53- and Bcl-2-negative leukemic K562 cell line showed resistant to DNA damage-induced Bax activation and apoptosis. The constitutive balanced ratio of Bax/Bcl-XL in K562 mitochondria allowed the formation of active Bax and cytochrome c release from mitochondria in the presence of a BH3-only protein, tBid, in a cell-free system. Bax transfection led to Bax undergoing a conformational change, translocation to mitochondria and homo-oligomerization but not apoptosis in the K562 cell line. After treatment with UV light, while Bcl-XL but not Bax translocated to mitochondria in K562, both Bax and Bcl-XL translocated to mitochondria in the Bax stable transfectant K/Bax cells. The increased ratio of Bax/Bcl-XL in K/Bax mitochondria led to an increased conformationally changed Bax, formation of the homo-multimer of Bax-Bax, and a reduced hetero-dimerization of Bax-Bcl-XL. Increased proportion of active Bax was accompanied with increased percentage of apoptosis. We therefore demonstrate that direct increase in the ratio of mitochondrial Bax/Bcl-XL can induce Bax activation in the p53- and Bcl-2-negative leukemic cells. Increased Bcl-XL translocation and failure in Bax translocation from cytosol to mitochondria play important roles in preventing Bax activation. 相似文献
4.
Aubert M Pomeranz LE Blaho JA 《Apoptosis : an international journal on programmed cell death》2007,12(1):19-35
Expression of HSV-1 genes leads to the induction of apoptosis in human epithelial HEp-2 cells but the subsequent synthesis
of infected cell protein prevents the process from killing the cells. Thus, viruses unable to produce appropriate prevention
factors are apoptotic. We now report that the addition of either a pancaspase inhibitor or caspase-9-specific inhibitor prevented
cells infected with an apoptotic HSV-1 virus from undergoing cell death. This result indicated that HSV-1-dependent apoptosis
proceeds through the mitochondrial apoptotic pathway. However, the pancaspase inhibitor did not prevent the release of cytochrome
c from mitochondria, implying that caspase activation is not required for this induction of cytochrome c release by HSV-1. The release of cytochrome c was first detected at 9 hpi while caspase-9, caspase-3 and PARP processing were detected at 12 hpi. Finally, Bax accumulated
at mitochondria during apoptotic, but not wild type HSV-1 infection. Together, these findings indicate that HSV-1 blocks apoptosis
by precluding mitochondrial cytochrome c release in a caspase-independent manner and suggest Bax as a target in infected human epithelial cells. 相似文献
5.
Chai WS Zhu XM Li SH Fan JX Chen BY 《Apoptosis : an international journal on programmed cell death》2008,13(6):833-843
Pseudomonas aeruginosa is a gram-negative opportunistic pathogen that is cytotoxic towards a variety of eukaryotic cells. To investigate the effect
of this bacterium on monocyte, we infected human U937 cells with the P. aeruginosa strain in vitro. To explore the expression of Bcl-2 and Bax as well as caspase-3/9 activation in the apoptosis of human U937
cells induced by P. aeruginosa, Hoechst 33258 staining and Giemsa staining as well as Flow cytometry analysis were used to determine the rate of apoptosis,
and the expressions of Bcl-2 and Bax were assayed by RT-PCR and Western blotting respectively. Bax protein conformation change
was assayed by immunoprecipitation. Cytochrome c release was measured by Western blotting. Moreover, exposure of U937 cells to P. aeruginosa measured caspase-3/9 activity. It was found that the apoptosis of human U937 cells could be induced by Pseudomonas aeruginosa in a dose- and time-dependent manner. Also, there were a tendency of alterations with an increased expression level of Bax
and a reduced expression level of Bcl-2, increased levels of cytochrome c release, and also with an increased activation of caspase-3/9 and Bax protein conformation change. For the evaluation of
the role of caspases, caspase-3/9 inhibitors Z-DEVD-FMK and Z-LEHD-FMK respectively were used. The results were further confirmed
by the observation that the caspase inhibitors Z-DEVD-FMK and Z-LEHD-FMK blocked P. aeruginosa-induced U937 apoptosis. It is concluded that P. aeruginosa can induce apoptosis with an up-regulated expression of Bax and a down-regulated expression of Bcl-2, which resulted in increased
levels of cytochrome c release and increased caspase-3 and -9 in human U937 cells. 相似文献
6.
Koc M Nad'ová Z Truksa J Ehrlichová M Kovár J 《Apoptosis : an international journal on programmed cell death》2005,10(2):381-393
In order to elucidate the mechanisms involved in apoptosis induction by iron deprivation, we compared cells sensitive (38C13) and resistant (EL4) to apoptosis induced by iron deprivation. Iron deprivation was achieved by incubation in a defined iron-free medium. We detected the activation of caspase-3 as well as the activation of caspase-9 in sensitive cells but not in resistant cells under iron deprivation. Iron deprivation led to the release of cytochrome c from mitochondria into the cytosol only in sensitive cells but it did not affect the cytosolic localization of Apaf-1 in both sensitive and resistant cells. The mitochondrial membrane potential (m) was dissipated within 24 h in sensitive cells due to iron deprivation. The antiapoptotic Bcl-2 protein was found to be associated with mitochondria in both sensitive and resistant cells and the association did not change under iron deprivation. On the other hand, under iron deprivation we detected translocation of the proapoptotic Bax protein from the cytosol to mitochondria in sensitive cells but not in resistant cells. Taken together, we suggest that iron deprivation induces apoptosis via mitochondrial changes concerning proapoptotic Bax translocation to mitochondria, collapse of the mitochondrial membrane potential, release of cytochrome c from mitochondria, and activation of caspase-9 and caspase-3. 相似文献
7.
Franziska B. Mullauer Jan H. Kessler Jan Paul Medema 《Apoptosis : an international journal on programmed cell death》2009,14(2):191-202
Betulinic acid (BetA) is a plant-derived pentacyclic triterpenoid that exerts potent anti-cancer effects in vitro and in vivo,
but is non toxic to untransformed cells. In our previous study we observed that BetA consistently induced cell death in a
broad panel of tumor cell lines. Apoptosis induced by BetA involves activation of caspases, PARP cleavage and DNA fragmentation
and was suggested to depend on the mitochondrial pathway. However, conflicting results have been reported with respect to
the role of the pro- and anti-apoptotic members of the Bcl-2 family, which are often aberrantly regulated in tumors and thereby
confer growth and survival advantages. Here we show that BetA-induced apoptosis critically depends on the release of cytochrome
c from the mitochondria and formation of the apoptosome. Nevertheless, over-expression of Bcl-2 or Bcl-XL only provides limited
protection against BetA-induced apoptosis. More importantly, Bax/Bak deficient cells are as sensitive to BetA as their wild-type
counterparts, suggesting that cytochrome c is released in a non-classical fashion. In agreement, pre-incubation with cyclosporin A indicated a crucial role for the
mitochondrial permeability transition pore (PT) in the induction of apoptosis. Our observations therefore indicate that BetA
affects mitochondria and induces cytochrome c release directly via PT Pore. This is only temporarily prevented by anti-apoptotic members of the Bcl-2 family, but independent
of Bax and Bak. These findings help to explain the remarkable broad efficacy of BetA against tumor cells of different origin
and its effect in tumor cells that are resistant to other chemotherapeutic agents. 相似文献
8.
We used a rat pheochromocytoma (PC12) cell line to study the effects of salidroside on hydrogen peroxide (H(2)O(2))-induced apoptosis. In PC12 cells, H(2)O(2)-induced apoptosis was accompanied by the down-regulation of Bcl-2, the up-regulation of Bax, the release of mitochondrial cytochrome c to cytosol, and the activation of caspase-3, -8 and -9. However, salidroside suppressed the down-regulation of Bcl-2, the up-regulation of Bax and the release of mitochondrial cytochrome c to cytosol. Moreover, salidroside attenuated caspase-3, -8 and -9 activation, and eventually protected cells against H(2)O(2)-induced apoptosis. Taken together, these results suggest that treatment of PC12 cells with salidroside can block H(2)O(2)-induced apoptosis by regulating Bcl-2 family members and by suppressing cytochrome c release and caspase cascade activation. 相似文献
9.
Paris C Bertoglio J Bréard J 《Apoptosis : an international journal on programmed cell death》2007,12(7):1257-1267
Hexadecylphosphocholine (HePC) is an anticancer agent whose effect has been shown to involve apoptosis induction but the signaling
pathways leading to apoptosis remain to be elucidated. We show here that HePC induces activation of caspase-9, -3, and -8
via the intrinsic pathway, release of cytochrome c, activation and relocation of Bax to the mitochondria as well as the cleavage of Bid. Moreover, a lysosomal pathway characterized
by partial lysosomal rupture, cathepsin B activation and relocation from lysosomes to the cytosol, is involved in HePC-induced
apoptosis. A cathepsin B/L inhibitor partially suppresses caspase activation and apoptosis induction, indicating signaling
between lysosomes and mitochondria. Conversely, the pancaspase inhibitor Q-VD-OPH inhibits lysosomal rupture, but only at
early time points, suggesting that immediate lysosomal rupture involves caspases. Overexpression of Bcl-2, an anti-apoptotic
protein known to prevent mitochondrial dysfunction, totally abrogates lysosomal destabilization and cell death. 相似文献
10.
Caspase-3-dependent cleavage of Bcl-2 promotes release of cytochrome c. 总被引:41,自引:0,他引:41
D G Kirsch A Doseff B N Chau D S Lim N C de Souza-Pinto R Hansford M B Kastan Y A Lazebnik J M Hardwick 《The Journal of biological chemistry》1999,274(30):21155-21161
Caspases are cysteine proteases that mediate apoptosis by proteolysis of specific substrates. Although many caspase substrates have been identified, for most substrates the physiologic caspase(s) required for cleavage is unknown. The Bcl-2 protein, which inhibits apoptosis, is cleaved at Asp-34 by caspases during apoptosis and by recombinant caspase-3 in vitro. In the present study, we show that endogenous caspase-3 is a physiologic caspase for Bcl-2. Apoptotic extracts from 293 cells cleave Bcl-2 but not Bax, even though Bax is cleaved to an 18-kDa fragment in SK-NSH cells treated with ionizing radiation. In contrast to Bcl-2, cleavage of Bax was only partially blocked by caspase inhibitors. Inhibitor profiles indicate that Bax may be cleaved by more than one type of noncaspase protease. Immunodepletion of caspase-3 from 293 extracts abolished cleavage of Bcl-2 and caspase-7, whereas immunodepletion of caspase-7 had no effect on Bcl-2 cleavage. Furthermore, MCF-7 cells, which lack caspase-3 expression, do not cleave Bcl-2 following staurosporine-induced cell death. However, transient transfection of caspase-3 into MCF-7 cells restores Bcl-2 cleavage after staurosporine treatment. These results demonstrate that in these models of apoptosis, specific cleavage of Bcl-2 requires activation of caspase-3. When the pro-apoptotic caspase cleavage fragment of Bcl-2 is transfected into baby hamster kidney cells, it localizes to mitochondria and causes the release of cytochrome c into the cytosol. Therefore, caspase-3-dependent cleavage of Bcl-2 appears to promote further caspase activation as part of a positive feedback loop for executing the cell. 相似文献
11.
Yang J Wang J Zhu S Chen X Wu H Yang D Zhang J 《Molecular and cellular biochemistry》2008,310(1-2):215-226
C-reactive protein (CRP) is an important predictive factor for cardiac disorders including acute myocardial infarction. Therapeutic
inhibition of CRP has been shown to be a promising new approach to cardioprotection in acute myocardial infarction in rat
models, but the direct effects of CRP on cardiac myocytes are poorly defined. In this study, we investigated the effects of
CRP on cardiac myocytes and its molecular mechanism involved. Neonatal rat cardiac myocytes were exposed to hypoxia for 8 h.
Hypoxia induced myocyte apoptosis under serum-deprived conditions, which was accompanied by cytochrome c release from mitochondria into cytosol, as well as activation of Caspase-9, Caspase-3. Hypoxia also increased Bax and decreased
Bcl-2 mRNA and protein expression, thereby significantly increasing Bax/Bcl-2 ratio. Cotreatment of CRP (100 μg/ml) under
hypoxia significantly increased the percentage of apoptotic myocytes, translocation of cytochrome c, Bax/Bcl-2 ratio, and the activity of Caspase-9 and Caspase-3. However, no effects were observed on myocyte apoptosis when
cotreatment of CRP under normoxia. Furthermore, Bcl-2 overexpression significantly improved cellular viability through inhibition
of hypoxia or cotreatment with CRP induced Bax/Bcl-2 ratio changes and cytochrome c release from mitochondria to cytosol, and significantly blocked the activity of Caspase-9 and Caspase-3. The present study
demonstrates that CRP could enhance apoptosis in hypoxia-stimulated myocytes through the mitochondrion-dependent pathway but
CRP alone has no effects on neonatal rat cardiac myocytes under normoxia. Bcl-2 overexpression might prevent CRP-induced apoptosis
by inhibiting cytochrome c release from the mitochondria and block activation of Caspase-9 and Caspase-3.
Jin Yang and Junhong Wang contributed equally to this work. 相似文献
12.
Gogada R Prabhu V Amadori M Scott R Hashmi S Chandra D 《The Journal of biological chemistry》2011,286(33):28749-28760
Resveratrol, a naturally occurring phytoalexin, is known to induce apoptosis in multiple cancer cell types, but the underlying molecular mechanisms remain unclear. Here, we show that resveratrol induced p53-independent, X-linked inhibitor of apoptosis protein (XIAP)-mediated translocation of Bax to mitochondria where it underwent oligomerization to initiate apoptosis. Resveratrol treatment promoted interaction between Bax and XIAP in the cytosol and on mitochondria, suggesting that XIAP plays a critical role in the activation and translocation of Bax to mitochondria. This process did not involve p53 but required accumulation of Bim and t-Bid on mitochondria. Bax primarily underwent homo-oligomerization on mitochondria and played a major role in release of cytochrome c to the cytosol. Bak, another key protein that regulates the mitochondrial membrane permeabilization, did not interact with p53 but continued to associate with Bcl-xL. Thus, the proapoptotic function of Bak remained suppressed during resveratrol-induced apoptosis. Caspase-9 silencing inhibited resveratrol-induced caspase activation, whereas caspase-8 knockdown did not affect caspase activity, suggesting that resveratrol induces caspase-9-dependent apoptosis. Together, our findings characterize the molecular mechanisms of resveratrol-induced caspase activation and subsequent apoptosis in cancer cells. 相似文献
13.
Neuroprotective effects of tetramethylpyrazine on hydrogen peroxide-induced apoptosis in PC12 cells 总被引:1,自引:0,他引:1
In the present study, we investigated the effects of tetramethylpyrazine (TMP) on hydrogen peroxide (H2O2)-induced apoptosis in PC12 cells. The apoptosis in H2O2-induced PC12 cells was accompanied by a decrease in Bcl-2/Bax protein ratio, release of cytochrome c to cytosol and the activation of caspase-3. TMP not only suppressed the down-regulation of Bcl-2, up-regulation of Bax and the release of mitochondrial cytochrome c to cytosol, but also attenuated caspase-3 activation and eventually protected against H2O2-induced apoptosis. These results indicated that TMP blocked H2O2-induced apoptosis by the regulation of Bcl-2 family members, suppression of cytochrome c release, and caspase cascade activation in PC12 cells. 相似文献
14.
Early events in Bcl-2-enhanced apoptosis 总被引:3,自引:0,他引:3
Liang Y Yan C Nylander KD Schor NF 《Apoptosis : an international journal on programmed cell death》2003,8(6):609-616
Transfection of PC12 pheochromocytoma cells with bcl-2 potentiates apoptosis induced by the antimitotic agent, neocarzinostatin (NCS). The mechanism of potentiation involves caspase 3-dependent cleavage of Bcl-2 to its pro-apoptotic counterpart, but the cellular events proximal to caspase 3 activation in this system are not known. Two min after initiation of NCS treatment, Bax begins to translocate from cytosol to the mitochondria; the mitochondrial localization of Bax persists for 30 min after NCS treatment. At the same time, cytochrome C is released from the mitochondria to cytosol. The mitochondrial membrane potential exhibits differential change in mock- and bcl-2-transfected PC12 cells. In mock-transfected PC12 cells, the mitochondrial membrane potential increases immediately, peaks at 15 min following initiation of NCS treatment, and drops thereafter. In contrast, in bcl-2-transfected PC12 cells, the membrane potential drops immediately following NCS treatment. Caspase 9 is activated and peaks at 10 min in both mock- and bcl-2 transfected PC12 cells, however, the peak activity of caspase 9 is higher and caspase 9 activation lasts longer (30 min) after the treatment in bcl-2 transfectants. Not until 30 min after initiation of a 1 h treatment with NCS is Bcl-2 protein cleaved in bcl-2-transfected cells. Thus, in bcl-2-transfected cells, the mitochondrial membrane potential drops and cytochrome C is released from the mitochondria despite the presence of large amounts of intact mitochondrial Bcl-2. This makes it unlikely that cleavage of Bcl-2 is the only factor involved in potentiation of NCS-induced apoptosis by Bcl-2. 相似文献
15.
Although resveratrol, an active ingredient derived from grapes and red wine, possesses chemopreventive properties against
several cancers, the molecular mechanisms by which it inhibits cell growth and induces apoptosis have not been clearly understood.
Here, we examined the molecular mechanisms of resveratrol and its interactive effects with TRAIL on apoptosis in prostate
cancer PC-3 and DU-145 cells. Resveratrol inhibited cell viability and colony formation, and induced apoptosis in prostate
cancer cells. Resveratrol downregulated the expression of Bcl-2, Bcl-XL and survivin and upregulated the expression of Bax, Bak, PUMA, Noxa, and Bim, and death receptors (TRAIL-R1/DR4 and TRAIL-R2/DR5).
Treatment of prostate cancer cells with resveratrol resulted in generation of reactive oxygen species (ROS), translocation
of Bax to mitochondria and subsequent drop in mitochondrial membrane potential, release of mitochondrial proteins (cytochrome
c, Smac/DIABLO, and AIF) to cytosol, activation of effector caspase-3 and caspase-9, and induction of apoptosis. Resveratrol-induced
ROS production, caspase-3 activity and apoptosis were inhibited by N-acetylcysteine. Bax was a major proapoptotic gene mediating the effects of resveratrol as Bax siRNA inhibited resveratrol-induced
apoptosis. Resveratrol enhanced the apoptosis-inducing potential of TRAIL, and these effects were inhibited by either dominant
negative FADD or caspase-8 siRNA. The combination of resveratrol and TRAIL enhanced the mitochondrial dysfunctions during
apoptosis. These properties of resveratrol strongly suggest that it could be used either alone or in combination with TRAIL
for the prevention and/or treatment of prostate cancer. 相似文献
16.
We have shown previously that depletion of polyamines delays apoptosis induced by camptothecin in rat intestinal epithelial cells (IEC-6). Mitochondria play an important role in the regulation of apoptosis in mammalian cells because apoptotic signals induce mitochondria to release cytochrome c. The latter interacts with Apaf-1 to activate caspase-9, which in turn activates downstream caspase-3. Bcl-2 family proteins are involved in the regulation of cytochrome c release from mitochondria. In this study, we examined the effects of polyamine depletion on the activation of the caspase cascade, release of cytochrome c from mitochondria, and expression and translocation of Bcl-2 family proteins. We inhibited ornithine decarboxylase, the first rate-limiting enzyme in polyamine synthesis, with alpha-difluoromethylornithine (DFMO) to deplete cells of polyamines. Depletion of polyamines prevented camptothecin-induced release of cytochrome c from mitochondria and decreased the activity of caspase-9 and caspase-3. The mitochondrial membrane potential was not disrupted when cytochrome c was released. Depletion of polyamines decreased translocation of Bax to mitochondria during apoptosis. The expression of antiapoptotic proteins Bcl-x(L) and Bcl-2 was increased in DFMO-treated cells. Caspase-8 activity and cleavage of Bid were decreased in cells depleted of polyamines. These results suggest that polyamine depletion prevents IEC-6 cells from apoptosis by preventing the translocation of Bax to mitochondria, thus preventing the release of cytochrome c. 相似文献
17.
Fatemeh Shaerzadeh Shabnam Zeighamy Alamdary Mohammad Ali Esmaeili Nazanin Namazi Sarvestani Fariba Khodagholi 《Neurochemical research》2011,36(12):2216-2226
Herein, we investigated the protective effect of Salvia sahendica against H2O2-induced cell death in rat pheochromocytoma (PC12) cells. Our data show that S. sahendica blocks apoptosis pathway by inhibition of cytochrome c release from mitochondria and leakage of calcium from endoplasmic reticulum. It also activates/inactivates two members of
Bcl-2 family, Bax and Bcl-2. Bax inhibition and Bcl-2 activation suppress release of cytochrome c from mitochondria that prevents cleavage of caspase-3. Besides S. sahendica suppresses ER stress via attenuation of intracellular levels of calcium. Suppression of ER stress decreased calpain activation
and subsequently cleavage of caspase-12. Altogether, these results indicate that S. sahendica protects PC12 cells treated with H2O2 via suppression of upstream factors of apoptosis pathway. While oxidative stress is an early event in Alzheimer disease,
it seems that S. sahendica prevents deleterious effects of reactive oxygen species by stabilizing mitochondrial membranes and inhibiting ER stress. 相似文献
18.
《Cell cycle (Georgetown, Tex.)》2013,12(22):2826-2834
We have shown previously that wild-type p53 renders H460 human lung cancer cells more sensitive to apoptosis induction by environmental carcinogen benzo[a]pyrene-7,8-diol-9,10-epoxide (BPDE), but the mechanism of cell death is not fully understood. The present study provides insights into the mechanism by which BPDE causes apoptosis in H460 cells. Exposure of H460 cells to BPDE resulted in a concentration-dependent apoptotic cell death characterized by cleavage of poly(ADP-ribose)polymerase, DNA condensation, and apoptotic histone-associated DNA fragments released into the cytosol. The BPDE-mediated release of apoptotic histone-associated DNA fragments into the cytosol was also observed in a normal bronchial epithelial cell line BEAS-2B. The BPDE-induced apoptosis in H460 cells correlated with up-regulation of pro-apoptotic protein Bak, down-regulation of anti-apoptotic Bcl-2 family members Bcl-2 and Bcl-xL, release of cytochrome c from mitochondria to the cytosol without a change in mitochondrial membrane potential or mitochondrial morphology (electron microscopy), and cleavage of caspase-8, -9, and -3. Ectopic expression of Bcl-2 failed to confer significant protection against BPDE-induced apoptosis in H460 cells. The SV40 immortalized mouse embryonic fibroblasts (MEFs) derived from Bak and Bax double knockout mice, but not Bid knockout mice, were significantly more resistant to BPDE-induced apoptosis compared with the MEFs derived from wild-type mice. The BPDE-induced apoptosis was partially but statistically significantly attenuated in the presence of specific inhibitors of caspase-9 (z-LEHDfmk) and caspase-8 (z-IETDfmk). In conclusion, the present study reveals that BPDE-induced apoptosis in H460 cells is associated with Bak induction and caspase activation but independent of Bcl-2. 相似文献
19.
We studied the mechanism of intra-mitochondrial death initiator caspase-9 activation by a redox response, in which hydrogen peroxide (H(2)O(2)) caused a subtle decrease in the inner membrane potential (Deltapsim) with little evidence of cytochrome c release. Initiation of the intra-mitochondrial autocleavage of procaspase-9 preceded the onset of caspase cascade induction in the cytosol. Purified mitochondria demonstrated procaspase-9 processing and releasing abilities when exposed to H(2)O(2). Bcl-2 overexpression caused accumulation of the active form caspase-9 in the mitochondria, rendering the cells resistant to the redox stress. Intriguingly, disulfide-bonded dimers of autoprocessed caspase-9 were generated in the mitochondria in the pre-apoptotic phase. Using a substrate-analog inhibitor, dimer formation of procaspase-9 was also detectable inside the mitochondria. Furthermore, thiol reductant thioredoxin blocked the caspase-9 activation step and the cell death induction. Thus, redox stress-responsive thiol-disulfide converting reactions in the mitochondrion seemed to mediate procaspase-9 assembly that allows autoprocessing. This study offers an explanation for the recent observation that Apaf-1-null cells can execute apoptosis, which can be blocked by Bcl-2, and supports the proposition that the cytochrome c-Apaf-1-procaspase-9 complex functions in the caspase amplification rather than in its initiation. 相似文献
20.
Criollo A Galluzzi L Maiuri MC Tasdemir E Lavandero S Kroemer G 《Apoptosis : an international journal on programmed cell death》2007,12(1):3-18
HeLa and HCT116 cells respond differentially to sorbitol, an osmolyte able to induce hypertonic stress. In these models, sorbitol
promoted the phenotypic manifestations of early apoptosis followed by complete loss of viability in a time-, dose-, and cell
type-specific fashion, by eliciting distinct yet partially overlapping molecular pathways. In HCT116 but not in HeLa cells,
sorbitol caused the mitochondrial release of the caspase-independent death effector AIF, whereas in both cell lines cytochrome
c was retained in mitochondria. Despite cytochrome c retention, HeLa cells exhibited the progressive activation of caspase-3, presumably due to the prior activation of caspase-8.
Accordingly, caspase inhibition prevented sorbitol-induced killing in HeLa, but only partially in HCT116 cells. Both the knock-out
of Bax in HCT116 cells and the knock-down of Bax in A549 cells by RNA interference reduced the AIF release and/or the mitochondrial
alterations. While the knock-down of Bcl-2/Bcl-XL sensitized to sorbitol-induced killing, overexpression of a Bcl-2 variant that specifically localizes to mitochondria (but
not of the wild-type nor of a endoplasmic reticulum-targeted form) strongly inhibited sorbitol effects. Thus, hyperosmotic
stress kills cells by triggering different molecular pathways, which converge at mitochondria where pro- and anti-apoptotic
members of the Bcl-2 family exert their control.
A. Criollo and L. Galluzzi contributed equally to this work. 相似文献