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1.
Respiration and Mitochondrial Membrane Potential Are not Required for Apoptosis and Anti-apoptotic Action of Bcl-2 in HeLa Cells 总被引:3,自引:0,他引:3
The release of cytochrome c from intermembrane space of mitochondria into cytosol is one of the critical events in apoptotic cell death. The important anti-apoptotic oncoprotein Bcl-2 inhibits this process. In the present study it was shown that apoptosis and release of cytochrome c induced by staurosporine or by tumor necrosis factor- in HeLa cells were not affected by inhibitors of respiration (rotenone, myxothiazol, antimycin A) or by uncouplers (CCCP, DNP) that decrease the membrane potential at the inner mitochondrial membrane. The inhibitors of respiration and the uncouplers did not affect also the anti-apoptotic activity of Bcl-2. 相似文献
2.
Rapak A Stasik I Ziolo E Strzadala L 《Apoptosis : an international journal on programmed cell death》2007,12(10):1873-1878
Nur77 is reported to undergo translocation to mitochondria in response to apoptotic signaling in a variety of cancer cell
lines. It was shown that on the mitochondrial membrane, Nur77 interacts with Bcl-2, leading to the conversion of this protein
from a protector to a killer with subsequent release of cytochrome c to the cytosol. Here it is shown that in thymic lymphoma cells resistant to calcium-mediated apoptosis, cytochrome c release is abolished despite of Nur77 mitochondrial targeting. However, cytochrome c release and apoptosis can be restored by treatment with FK506. Hence, the molecular target regulation of the sensitivity
of lymphoma cells to calcium signaling is associated with cytochrome c release and is FK506 sensitive. These results provide new insight into the role of FK506-sensitive factors as a critical
link between calcium signaling and resistance of lymphoma cells to death. 相似文献
3.
Zecchin KG Seidinger AL Chiaratti MR Degasperi GR Meirelles FV Castilho RF Vercesi AE 《Journal of bioenergetics and biomembranes》2007,39(2):186-194
It has been previously shown that Walker 256 tumor cells express a high content of the anti-apoptotic protein Bcl-2 which
protects mitochondria against the damaging effects of Ca2+. In the present study, we analyze H2O2-induced apoptotic death in two different types of tumor cells: Walker 256 and SCC-25. Treatment with H2O2 (4mM) increased reactive oxygen species generation and the concentration of cytosolic free Ca2+. These alterations preceded apoptosis in both cell lines. In Walker cells, which show a high Bcl-2/Bax ratio, apoptosis was
dependent on calcineurin activation and independent of changes in mitochondrial membrane potential (Δ < eqid1 > m), as well as cytochrome c release. In contrast, in SCC-25 cells, which show a lower Bcl-2/Bax ratio, apoptosis was preceded by a decrease in Δ < eqid2 > m, mitochondrial permeability transition, and cytochrome c release. Caspase-3 activation occurred in both cell lines. The data suggest that although the high Bcl-2/Bax ratio protected
the mitochondria of Walker cells from oxidative stress, it was not sufficient to prevent apoptosis through calcineurin pathways. 相似文献
4.
Phosphorothioate oligonucleotides reduce mitochondrial outer membrane permeability to ADP 总被引:2,自引:0,他引:2
Tan W Lai JC Miller P Stein CA Colombini M 《American journal of physiology. Cell physiology》2007,292(4):C1388-C1397
G3139, an antisense Bcl-2 phosphorothioate oligodeoxyribonucleotide, induces apoptosis in melanoma and other cancer cells. This apoptosis happens before and in the absence of the downregulation of Bcl-2 and thus seems to be Bcl-2-independent. Binding of G3139 to mitochondria and its ability to close voltage-dependent anion-selective channel (VDAC) have led to the hypothesis that G3139 acts, in part, by interacting with VDAC channels in the mitochondrial outer membrane (21). In this study, we demonstrate that G3139 is able to reduce the mitochondrial outer membrane permeability to ADP by a factor of 6 or 7 with a Ki between 0.2 and 0.5 µM. Because VDAC is responsible for this permeability, this result strengthens the aforesaid hypothesis. Other mitochondrial respiration components are not affected by [G3139] up to 1 µM. Higher levels begin to inhibit respiration rates, decrease light scattering and increase uncoupled respiration. These results agree with accumulating evidence that VDAC closure favors cytochrome c release. The speed of this effect (within 10 min) places it early in the apoptotic cascade with cytochrome c release occurring at later times. Other phosphorothioate oligonucleotides are also able to induce VDAC closure, and there is some length dependence. The phosphorothioate linkages are required to induce the reduction of outer membrane permeability. At levels below 1 µM, phosphorothioate oligonucleotides are the first specific tools to restrict mitochondrial outer membrane permeability. respiration; voltage-dependent anion-selective channel; apoptosis; cell death 相似文献
5.
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
6.
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
7.
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
8.
Cardiolipin: Setting the beat of apoptosis 总被引:4,自引:0,他引:4
Gonzalvez F Gottlieb E 《Apoptosis : an international journal on programmed cell death》2007,12(5):877-885
Cardiolipin (CL) is a mitochondria-specific phospholipid which is known to be intimately linked with the mitochondrial bioenergetic
machinery. Accumulating evidence now suggests that this unique lipid also has active roles in several of the mitochondria-dependant
steps of apoptosis. CL is closely associated with cytochrome c at the outer leaflet of the mitochondrial inner membrane. This interaction makes the process of cytochrome c release from mitochondria more complex than previously assumed, requiring more than pore formation in the mitochondrial outer
membrane. While CL peroxidation could be crucial for enabling cytochrome c dissociation from the mitochondrial inner membrane, cytochrome c itself catalyzes CL peroxidation. Moreover, peroxy-CL directly activates the release of cytochrome c and other apoptogenic factors from the mitochondria. CL is also directly involved in mitochondrial outer membrane permeabilization
by enabling docking and activation of pro-apoptotic Bcl-2 proteins. It appears therefore that CL has multiple roles in apoptosis
and that CL metabolism contributes to the complexity of the apoptotic process. 相似文献
9.
Roman A. Eliseev 《BBA》2003,1604(1):1-5
The mechanism of cytochrome c release from mitochondria in apoptosis remains obscure, although it is known to be regulated by bcl-2 family proteins. Here we describe a set of novel apoptotic phenomena—stimulation of the mitochondrial potassium uptake preceding cytochrome c release and regulation of such potassium uptake by bcl-2 family proteins. As a result of increased potassium uptake, mitochondria undergo moderate swelling sufficient to release cytochrome c. Overexpression of bcl-2 protein prevented the mitochondrial potassium uptake as well as cytochrome c release in apoptosis. Bcl-2 was found to upregulate the mitochondrial potassium efflux mechanism—the K/H exchanger. Specific activation of the mitochondrial K-uniporter led to cytochrome c release, which was inhibited by bcl-2. tBid had an opposite effect—it stimulated mitochondrial potassium uptake resulting in cytochrome c release. The described counter-regulation of mitochondrial potassium transport by bcl-2 and Bid suggests a novel view of a mechanism of cytochrome c release from mitochondria in apoptosis. 相似文献
10.
Liu GY Liao YF Hsu PC Chang WH Hsieh MC Lin CY Hour TC Kao MC Tsay GJ Hung HC 《Apoptosis : an international journal on programmed cell death》2006,11(10):1773-1788
Antizymes delicately regulate ornithine decarboxylase (ODC) enzyme activity and polyamine transportation. One member of the
family, antizyme-1, plays vital roles in molecular and cellular functions, including developmental regulation, cell cycle,
proliferation, cell death, differentiation and tumorigenesis. However, the question of how does it participate in the cell
apoptotic mechanism is still unsolved. To elucidate the contribution of human antizyme-1 in haematopoietic cell death, we
examine whether inducible overexpression of antizyme enhances apoptotic cell death. Antizyme reduced the viability in a dose-
and time-dependent manner of human leukemia HL-60 cells, acute T leukemia Jurkat cells and mouse macrophage RAW 264.7 cells.
The apoptosis-inducing activities were determined by nuclear condensation, DNA fragmentation, sub-G1 appearance, loss of mitochondrial membrane potential (Δψ
m
), release of mitochondrial cytochrome c into cytoplasm and proteolytic activation of caspase 9 and 3. Following conditional antizyme overexpression, all protein
levels of cyclin-dependent kinases (Cdks) and cyclins are not significantly reduced, except cyclin D, before their entrance
into apoptotic cell death. However, introduced cyclin D1 into Jurkat T tetracycline (Tet)-On cell system still couldn’t rescue
cells from apoptosis. Antizyme doesn’t influence the expression of tumor suppressor p53 and its downstream p21, but it interferes
in the expressions of Bcl-2 family. Inducible antizyme largely enters mitochondria resulting in cytochrome c release from mitochondria to cytosol following Bcl-xL decrease and Bax increase. According to these data, we suggest that
antizyme induces apoptosis mainly through mitochondria-mediated and cell cycle-independent pathway. Furthermore, antizyme
induces apoptosis not only by Bax accumulation reducing the function of the Bcl-2 family, destroying the Δψ
m
, and releasing cytochrome c to cytoplasm but also by the activation of apoptosomal caspase cascade. 相似文献
11.
Trevor C. Koekemoer Willem Oelofsen 《Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology》2001,129(4)
The capacity of white adipose tissue mitochondria to support a high beta-oxidative flux was investigated by comparison to liver mitochondria. Based on marker enzyme activities and electron microscopy, the relative purity of the isolated mitochondria was similar thus allowing a direct comparison on a protein basis. The results confirm the comparable capacity of adipose tissue and liver mitochondria for palmitoyl-carnitine oxidation. Relative to liver, both citrate synthase and α-ketoglutarate dehydrogenase were increased 7.87- and 10.38-fold, respectively. In contrast, adipose tissue NAD-isocitrate dehydrogenase was decreased (2.85-fold). Such modifications in the citric acid cycle are expected to severely restrict citrate oxidation in porcine adipose tissue. Except for cytochrome c oxidase, activities of the enzyme complexes comprising the electron transport chain were not significantly different. The decrease in adipose cytochrome c oxidase activity could partly be attributed to a decreased inner membrane as suggested by lipid and enzyme analysis. In addition, Western blotting indicated that adipose and liver mitochondria possess similar quantities of cytochrome c oxidase protein. Taken together these results indicate that not only is the white adipose tissue protoplasm relatively rich in mitochondria, but that these mitochondria contain comparable enzymatic machinery to support a relatively high beta-oxidative rate. 相似文献
12.
Oursler MJ Bradley EW Elfering SL Giulivi C 《American journal of physiology. Cell physiology》2005,288(1):C156-C168
Two unresolved aspects of the role of mitochondria-derived cytochrome c in apoptosis are whether there is a separate pool of cytochrome c within mitochondria that participates in the activation of apoptosis and whether a chemically modified cytochrome c drives apoptosis. These questions were investigated using osteoclasts, because they are rich in mitochondria and because osteoclast apoptosis is critical in bone metabolism regulation. H2O2 production was increased during culture, preceding cytochrome c release; both processes occurred anterior to apoptosis. With the addition of a mitochondrial uncoupler, H2O2 production and apoptosis were blocked, indicating the prominent role of mitochondria-derived H2O2. Trapping H2O2-derived hydroxyl radical decreased apoptosis. Cytosolic cytochrome c was originated from a single mitochondrial compartment, supporting a common pool involved in respiration and apoptosis, and it was chemically identical to the native form, with no indication of oxidative or nitrative modifications. Protein levels of Bcl-2 and Bc-xL were decreased before apoptosis, whereas expression of wild-type Bcl-2 repressed apoptosis, confirming that cytochrome c release is critical in initiating apoptosis. Cytosolic cytochrome c participated in activating caspase-3 and -9, both required for apoptosis. Collectively, our data indicate that the mitochondria-dependent apoptotic pathway is one of the major routes operating in osteoclasts. reactive oxygen species; nitric oxide; free radicals; caspase 相似文献
13.
Eri Oyanagi Hiromi Yano Masataka Uchida Kozo Utsumi Junzo Sasaki 《Biochemical and biophysical research communications》2011,(1):61
Cardiovascular risks are frequently accompanied by high serum fatty acid levels. Although recent studies have shown that fatty acids affect mitochondrial function and induce cell apoptosis, l-carnitine is essential for the uptake of fatty acids by mitochondria, and may attenuate the mitochondrial dysfunction and apoptosis of cardiocytes. This study aimed to elucidate the activity of l-carnitine in the prevention on fatty acid-induced mitochondrial membrane permeability transition and cytochrome c release using isolated cardiac mitochondria from rats. Palmitoyl-CoA-induced mitochondrial respiration that was observed with l-carnitine was inhibited with oligomycin. The palmitoyl-CoA-induced mitochondrial membrane depolarization and swelling were greatly inhibited by the presence of l-carnitine. In ultrastructural observations, terminally swollen and ruptured mitochondria with little or no distinguishable cristae structures were induced by treatment with palmitoyl-CoA. However, the severe morphological damage in cardiac mitochondria was dramatically inhibited by pretreatment with l-carnitine. Treatment with l-carnitine also attenuated 4-hydroxy-l-phenylglycine- and rotenone-induced mitochondrial swelling even when the l-carnitine could not protect against the decrease in oxygen consumption associated with these inhibitors. Furthermore, l-carnitine completely inhibited palmitoyl-CoA-induced cytochrome c release. We concluded that l-carnitine is essential for cardiac mitochondria to attenuate the membrane permeability transition, and to maintain the ultrastructure and membrane stabilization, in the presence of high fatty acid β-oxidation. Consequently, the cells may be protected against apoptosis by l-carnitine through inhibition of the fatty acid-induced cytochrome c release. 相似文献
14.
Li YC Lin HJ Yang JH Yang JS Ho HC Chang SJ Hsai TC Lu HF Huang AC Chung JG 《Neurochemical research》2009,34(3):418-429
Studies were designed to investigate the effects of baicalein on mouse–rat hybrid retina ganglion cells (N18) to better understand
its effect on apoptosis and apoptosis-related genes in vitro. Cell viability, reactive oxygen species (ROS), cytoplasmic Ca2+, mitochondrial membrane potential (MMP), apoptosis induction, and caspases-3 activity were examined by flow cytometric assay.
Apoptosis-associated proteins such as p53, Bax, Bcl-2, cytochrome c, and caspase-3 were examined by Western blot. We demonstrated the increase in the levels of p53, Bax, and cytochrome c and decrease in the level of Bcl-2, which are associated with the induction of apoptotic cell death after 24 h treatment
with baicalein in N18 cells. Baicalein induced an increase in the cytoplasmic levels of ROS and Ca2+ in 1 h and reached their peak at 3 h, and thereafter a loss of MMP by flow cytometry. We also demonstrated a release of the
cytochrome c from mitochondria into cytosol and an activation of caspase-3, which led to the occurrence of apoptosis in N18 cells treated
with baicalein by Western blot. Pretreatment was conducted with BAPTA (intracellular calcium chelator) in baicalein-treated
cells, the decline of MMP was recovered, and the increase in the level of cytoplasmic Ca2+ was suppressed, and the proportion of apoptosis was also markedly diminished. In conclusion, our data suggests that oxidative
stress and cellular Ca2+ modulates the baicalein-induced cell death via a Ca2+-dependent mitochondrial death pathway in N18 cells. 相似文献
15.
Photodynamic therapy-induced death of HCT 116 cells: Apoptosis with or without Bax expression 总被引:2,自引:0,他引:2
Chiu SM Xue LY Azizuddin K Oleinick NL 《Apoptosis : an international journal on programmed cell death》2005,10(6):1357-1368
Cell death following photodynamic therapy (PDT) with the photosensitizer Pc 4 involves the intrinsic pathway of apoptosis.
To evaluate the importance of Bax in apoptosis after PDT, we compared the PDT responses of Bax-proficient (Bax+/−) and Bax knock-out (BaxKO) HCT116 human colon cancer cells. PDT induced a slow apoptotic process in HCT Bax+/− cells following a long delay in the activation of Bax and release of cytochrome c from mitochondria. Although cytochrome c was not released from mitochondria following PDT in BaxKO cells, an alternative mechanism of caspase-dependent apoptosis
with extensive chromatin and DNA degradation was found in these cells. This alternative process was less efficient and slower
than the normal apoptotic process observed in Bax+/− cells. Early events upon PDT, such as the loss of mitochondrial membrane potential, photodamage to Bcl-2, and activation
of p38 MAP kinase, were observed in both HCT116 cell lines. In spite of differences in the efficiency and mode of apoptosis
induced by PDT in the Bax+/− and BaxKO cells, they were found to be equally sensitive to killing by PDT, as determined by loss of clonogenicity. Thus,
for Pc 4-PDT, the commitment to cell death occurs prior to and independent of Bax activation, but the process of cellular
disassembly differs in Bax-expressing vs. non-expressing cells. 相似文献
16.
Summary. Programmed cell death plays a vital role in normal plant development, response to environmental stresses, and defense against
pathogen attack. Different types of programmed cell death occur in plants and the involvement of mitochondria is still under
investigation. In sycamore (Acer pseudoplatanus L.) cultured cells, the phytotoxin fusicoccin induces cell death that shows apoptotic features, including chromatin condensation,
DNA fragmentation, and release of cytochrome c from mitochondria. In this work, we show that cyclosporin A, an inhibitor of the permeability transition pore of animal mitochondria,
inhibits the cell death, DNA fragmentation, and cytochrome c release induced by fusicoccin. In addition, we show that fusicoccin induces a change in the shape of mitochondria which is
not prevented by cyclosporin A. These results suggest that the release of cytochrome c induced by fusicoccin occurs through a cyclosporin A-sensitive system that is similar to the permeability transition pore
of animal mitochondria and they make it tempting to speculate that this release may be involved in the phytotoxin-induced
programmed cell death of sycamore cells.
Correspondence and reprints: Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, Piazza
della Scienza 2, 20126 Milano, Italy. 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.
Caspases play important roles in the initiation and progression of apoptosis. In experimental models of ATP depletion, we
have demonstrated the activation of caspase-9, -8, and -3, which is followed by the development of apoptotic morphology. To
determine the specific contribution of caspase-9 to ATP depletion-induced apoptosis, we transfected renal epithelial cells
with its endogenous dominant-negative inhibitor caspase-9S. Two cell clones with stable transfection were obtained. These
clones expressed caspase-9S, and the cytosol isolated from these cells was resistant to cytochrome c-induced caspase activation in vitro. The clones were then examined for ATP depletion-induced apoptosis. Compared with the wild-type cells, the caspase-9S clones
were markedly resistant to apoptosis in this model. Caspase activation was also inhibited. Surprisingly, these clones also
showed significantly less cytochrome c release during ATP-depletion. Moreover, Bax translocation to mitochondria was inhibited, suggesting that these clones were
resistant to apoptosis not only at the cytosolic caspase activation level but also at the upstream mitochondrial level. To
gain insights into the mitochondrial resistance, we analyzed the expression of Bcl-2 family proteins. While the expression
of Bax, Bak, and Bcl-2 was comparable to the wild-type cells, the selected clones showed specific up-regulation of Bcl-XL,
an anti-apoptotic protein. We conclude that the selected clones were resistant to apoptosis at two levels. In the cytosol,
they expressed dominant negative caspase-9, and at the mitochondria they up-regulated Bcl-XL. 相似文献
19.
Duan S Hajek P Lin C Shin SK Attardi G Chomyn A 《The Journal of biological chemistry》2003,278(2):1346-1353
We have shown here that the apoptosis inducer staurosporine causes an early decrease in the endogenous respiration rate in intact 143B.TK(-) cells. On the other hand, the activity of cytochrome c oxidase is unchanged for the first 8 h after staurosporine treatment, as determined by oxygen consumption measurements in intact cells. The decrease in the endogenous respiration rate precedes the release of cytochrome c from mitochondria. Moreover, we have ruled out caspases, permeability transition, and protein kinase C inhibition as being responsible for the decrease in respiration rate. Furthermore, overexpression of the gene for Bcl-2 does not prevent the decrease in respiration rate. The last finding suggests that Bcl-2 acts downstream of the perturbation in respiration. The evidence of normal enzymatic activities of complex I and complex III in staurosporine-treated 143B.TK(-) osteosarcoma cells indicates that the cause of the respiration decrease is probably an alteration in the permeability of the outer mitochondrial membrane. Presumably, the voltage-dependent anion channel closes, thereby preventing ADP and oxidizable substrates from being taken up into mitochondria. This interpretation was confirmed by another surprising finding, namely that, in staurosporine-treated 143B.TK(-) cells permeabilized with digitonin at a concentration not affecting the mitochondrial membranes in naive cells, the outer mitochondrial membrane loses its integrity; this leads to a reversal of its impermeability to exogenous substrates. The loss of outer membrane integrity leads also to a massive premature release of cytochrome c from mitochondria. Most significantly, Bcl-2 overexpression prevents the staurosporine-induced hypersensitivity of the outer membrane to digitonin. Our experiments have thus revealed early changes in the outer mitochondrial membrane, which take place long before cytochrome c is released from mitochondria in intact cells. 相似文献
20.
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