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1.
Inhibition of nitric-oxide-mediated apoptosis in Jurkat leukemia cells despite cytochrome c release 总被引:1,自引:0,他引:1
Umansky V Ratter F Lampel S Bucur M Schirrmacher V Ushmorov A 《Experimental cell research》2001,265(2):274-282
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.
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
3.
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
4.
The involvement of mitochondria and the caspase-9 activation pathway in rituximab-induced apoptosis in FL cells 总被引:1,自引:0,他引:1
Jonna Eeva Ulla Nuutinen Antti Ropponen Mikko Mättö Mine Eray Riikka Pellinen Jarmo Wahlfors Jukka Pelkonen 《Apoptosis : an international journal on programmed cell death》2009,14(5):687-698
Despite the wide use of anti-CD20 antibody rituximab in the cancer treatment of B cell malignancies, the signalling pathways
of CD20-induced apoptosis are still not understood. By using dominant negative (DN)-caspase-9 overexpressing follicular lymphoma
cells we demonstrated that the activation of caspase-9 was essential for rituximab-mediated apoptosis. The death receptor
pathway mediated by caspase-8 activation was not involved in rituximab-mediated apoptosis since overexpression of FLIPshort or FLIPlong proteins, inhibitors of caspase-8 activation, could not inhibit rituximab-induced apoptosis. However, the death receptor
pathway activation by anti-Fas antibodies showed an additive effect on rituximab-induced apoptosis. The stabilisation of the
mitochondrial outer membrane by Bcl-xL overexpression inhibited cell death, showing the important role of mitochondria in rituximab-induced apoptosis. Interestingly,
the rituximab-induced release of cytochrome c and collapse of mitochondrial membrane potential were regulated by caspase-9. We suggest that caspase-9 and downstream caspases
may feed back to mitochondria to amplify mitochondrial disruption during intrinsic apoptosis. 相似文献
5.
Maria Piqu Montserrat Barragn Mireia Dalmau Beatriz Bellosillo Gabriel Pons Joan Gil 《FEBS letters》2000,480(2-3)
Aspirin and other non-steroidal anti-inflammatory drugs induce apoptosis in many cell types. Although the involvement of caspases has been demonstrated, the mechanism leading to caspase activation remains unknown. We have studied the role of the mitochondrial pathway in aspirin-induced apoptosis. The apoptotic effect of aspirin was analyzed in different cell lines (Jurkat, MOLT-4, Raji and HL-60) showing induction of mitochondrial cytochrome c release and caspases 9, 3 and 8 processing. Furthermore, early aspirin-induced cytochrome c release was not affected by the caspase inhibitor Z-VAD·fmk and preceded loss of mitochondrial membrane potential. Therefore, aspirin-induced apoptosis involves caspase activation through cytochrome c release. 相似文献
6.
Hearps AC Burrows J Connor CE Woods GM Lowenthal RM Ragg SJ 《Apoptosis : an international journal on programmed cell death》2002,7(5):387-394
Whilst the role of ceramide, a second messenger of the sphingolipid family, in the initiation of receptor-mediated apoptosis is controversial, a growing body of evidence is emerging for a role of ceramide in the amplification of apoptosis via mitochondrial perturbations that culminate in the activation of execution caspases. Treatment of Jurkat T cells with the cell-permeable analog, C2-ceramide, resulted in the rapid onset of apoptosis as evidenced by Annexin V-FITC staining of externalised phosphatidylserine residues. Cells bearing this early apoptotic marker had a reduced mitochondrial transmembrane potential (m) that was preceded by the release of cytochrome c from mitochondria. Subsequent activation of caspase-3 provides the link between these ceramide-induced mitochondrial changes and execution caspases that ultimately result in the physical destruction of the cell. Collectively these results demonstrate that ceramide signalling results in caspase-mediated apoptosis via mitochondrial cytochrome c release and are further supportive of the role of ceramide in the amplification of apoptosis. 相似文献
7.
Cione E Tucci P Senatore V Perri M Trombino S Iemma F Picci N Genchi G 《Journal of bioenergetics and biomembranes》2008,40(1):19-26
Ferulic acid plays a chemopreventive role in cancer by inducing tumor cells apoptosis. As mitochondria play a key role in
the induction of apoptosis in many cells types, here we investigate the mitochondrial permeability transition (MPT) and the
release of cytochrome c induced by ferulic acid and its esters in rat testes mitochondria, in TM-3 and MLTC-1 cells. While ferulic acid, but not
its esters, induced MPT and cytochrome c release in rat testes isolated mitochondria, in TM-3 cells we found that both ferulic acid and its esters induced cytochrome
c release from mitochondria in a dose-dependent manner, suggesting a potential target of these compounds in the induction of
cell apoptosis. The apoptosis induced by ferulic acid is therefore associated with the mitochondrial pathway involving cytochrome
c release and caspase-3 activation.
Cione and Tucci have equally contributed to this article. 相似文献
8.
Park HS Jun DY Han CR Kim YH 《Biochemical and biophysical research communications》2008,377(1):280-285
Phenylalanine analog, ρ-fluorophenylalanine (pFPhe)-mediated cytotoxicity and several apoptotic events including mitochondrial cytochrome c release, activation of caspase-9, -3, and -8, Bid cleavage, degradation of PARP and PLCγ-1, and DNA fragmentation were more significant in p56lck-deficient Jurkat T cells (JCaM1.6) than in wild-type Jurkat T cells (E6.1). The susceptibility of JCaM1.6 toward apoptogenic activity of pFPhe decreased after acquisition of p56lck by transfection. The p56lck kinase activity increased 1.6-fold at 15-30 min after pFPhe treatment. The pan-caspase inhibitor (z-VAD-fmk) completely blocked the pFPhe-mediated apoptotic changes except caspase-9 activation. The caspase-8 inhibitor (z-IETD-fmk), which failed to influence pFPhe-induced caspase-9 activation, completely blocked caspase-8 activation and PLCγ-1 degradation with a marked reduction in caspase-3 activation and PARP degradation, indicating pFPhe-induced caspase-8 activation as a downstream event of mitochondria-dependent activation of caspase-9. These results indicate that the deficiency of p56lck augments pFPhe-induced mitochondrial cytochrome c release and resultant apoptotic cell death in Jurkat T cells. 相似文献
9.
Tsuruga M Nakajima H Ozawa S Togashi M Chang YC Ando K Magae J 《Apoptosis : an international journal on programmed cell death》2004,9(4):429-435
Apoptosis can be induced by various stimuli such as the ligands of death receptors, chemotherapeutic drugs and irradiation. It is generally believed that chemotherapeutic drugs induce mitochondrial damage, cytochrome c release and activation of caspase-9, leading to apoptosis. Here, we found that an isoprenoid antibiotic, 4-O-methyl ascochlorin, significantly induces typical apoptotic events in Jurkat cells including the degradation of poly (ADP-ribose) polymerase, DNA fragmentation, activation of caspase-3, -9 and -8, and cytochrome c release from mitochondria. Similar to Fas stimulation, 4-O-methyl ascochlorin but not staurosporine, cycloheximide and actinomycin D, induced apoptosis in SKW6.4 cells, in which apoptosis is strongly dependent on death-inducing signaling-complex. Bcl-2 overexpression in Jurkat cells completely suppressed the apoptosis, but procaspase-9 processing was partially induced. A caspase-8 inhibitor, IETD-fmk, effectively suppressed poly (ADP-ribose) polymerase cleavage and cytochrome c release. However, 4-O-methyl ascochlorin induced apoptosis in Jurkat cells deficient of caspase-8 or Fas-associated death domain protein. These results suggest that 4-O-methyl ascochlorin induces apoptosis through the mechanism distinct from conventional apoptosis inducers. 相似文献
10.
Apoptosis is mediated by members of the caspase family of proteases which can be activated by release of mitochondrial cytochromec.Additional members of the caspase family are activated at the cell surface in response to direct stimulus from the external environment such as by activation of the Fas receptor. It has been suggested that these upstream caspases directly activate the downstream caspases which would obviate a role for cytochromecin apoptosis induced by the Fas receptor. We demonstrate that cytochromecis released from mitochondria of Jurkat cells in response to both staurosporine and an agonistic anti-Fas antibody and that only the latter is inhibited by the caspase inhibitor z-VAD-FMK. This suggests that an upstream caspase such as caspase-8 is required for the Fas-mediated release of mitochondrial cytochromec.The protein phosphatase inhibitor calyculin A prevented cytochromecrelease and apoptosis induced by both agents, suggesting that release of cytochromecis required in both models. Zinc, once thought of as an endonuclease inhibitor, has previously been shown to prevent the activation of caspase-3. We show that zinc prevents the activation of downstream caspases and apoptosis induced by both insults, yet does not prevent release of mitochondrial cytochromec.The ability of calyculin A and zinc to prevent DNA digestion implies that the mitochondrial pathway is important for induction of apoptosis by both agents. These results do not support an alternative pathway in which caspase-8 directly activates caspase-3. These results also demonstrate that a critical protein phosphatase regulates the release of cytochromecand apoptosis induced by both insults. 相似文献
11.
David M. Conrad Suzanne J. Furlong Carolyn D. Doucette Kenneth A. West David W. Hoskin 《Apoptosis : an international journal on programmed cell death》2010,15(5):597-607
Flunarizine is a Ca2+ channel blocker that can be either cytoprotective or cytotoxic, depending on the cell type that is being examined. We show
here that flunarizine was cytotoxic for Jurkat T-leukemia cells, as well as for other hematological maligancies, but not for
breast or colon carcinoma cells. Treatment of Jurkat cells with flunarizine resulted in caspase-3 activation, poly (ADP-ribose)
polymerase cleavage, and laddering of DNA fragments, all of which are hallmarks of apoptosis. Flunarizine-induced DNA fragmentation
was inhibited by the caspase-3 inhibitor z-DEVD-fmk, the caspase-8/caspase-10 inhibitor z-IETD-fmk, and the caspase-10 inhibitor
z-AEVD-fmk, but was not reduced in caspase-8-deficient Jurkat cells, indicating the involvement of caspase-10 upstream of
caspase-3 activation. Interestingly, FADD recruitment to a death receptor was not involved since flunarizine caused DNA fragmentation
in FADD-deficient Jurkat cells. Flunarizine treatment of Jurkat cells also resulted in reactive oxygen species production,
dissipation of mitochondrial transmembrane potential, release of cytochrome c from mitochondria, and caspase-9 activation, although none of these events were necessary for apoptosis induction. Collectively,
these findings indicate that flunarizine triggers apoptosis in Jurkat cells via FADD-independent activation of caspase-10.
Flunarizine warrants further investigation as a potential anti-cancer agent for the treatment of hematological malignancies. 相似文献
12.
Yamaguchi T Hashiguchi K Katsuki S Iwamoto W Tsuruhara S Terada S 《Cellular & molecular biology letters》2008,13(1):49-57
We previously demonstrated that caspase-3, an executioner of apoptosis, is activated in the pressure-induced apoptosis of
murine erythroleukemia (MEL) cells (at 100 MPa). Here, we examined the pathway of caspase-3 activation using peptide substrates
and caspase inhibitors. Using the substrates of caspases-8 and -9, it was found that both are activated in cells under high
pressure. The production of nuclei with sub-G1 DNA content in 100 MPa-treated MEL cells was suppressed by inhibitors of caspases-8
and -9, and pan-caspase. In 100 MPa-treated cells, pan-caspase inhibitor partially prevented the cytochrome c release from the mitochondria and the breakdown of mitochondrial membrane potential. These results suggest that the intrinsic
and extrinsic pathways are activated in apoptotic signaling during the high pressure-induced death of MEL cells. 相似文献
13.
Mary E. Shawgo Shary N. Shelton John D. Robertson 《The Journal of biological chemistry》2009,284(48):33447-33455
Activation of executioner caspases during receptor-mediated apoptosis in type II cells requires the engagement of the mitochondrial apoptotic pathway. Although it is well established that recruitment of mitochondria in this context involves the cleavage of Bid to truncated Bid (tBid), the precise post-mitochondrial signaling responsible for executioner caspase activation is controversial. Here, we used distinct clones of type II Jurkat T-lymphocytes in which the mitochondrial apoptotic pathway had been inhibited to investigate the molecular requirements necessary for Fas-induced apoptosis. Cells overexpressing either Bcl-2 or Bcl-xL were protected from apoptosis induced by agonistic anti-Fas antibody. By comparison, Apaf-1-deficient Jurkat cells were sensitive to anti-Fas, exhibiting Bid cleavage, Bak activation, the release of cytochrome c and Smac, and activation of executioner caspase-3. Inhibiting downstream caspase activation with the pharmacological inhibitor Z-DEVD-fmk or by expressing the BIR1/BIR2 domains of X-linked inhibitor of apoptosis protein (XIAP) decreased all anti-Fas-induced apoptotic changes. Additionally, pretreatment of Bcl-xL-overexpressing cells with a Smac mimetic sensitized these cells to Fas-induced apoptosis. Combined, our findings strongly suggest that Fas-mediated activation of executioner caspases and induction of apoptosis do not depend on apoptosome-mediated caspase-9 activation in prototypical type II cells. 相似文献
14.
Furre IE Møller MT Shahzidi S Nesland JM Peng Q 《Apoptosis : an international journal on programmed cell death》2006,11(11):2031-2042
Photodynamic therapy (PDT) is a cancer treatment based on the interaction of a photosensitizer, light and oxygen. PDT with
the endogenous photosensitizer, protoporphyrin IX (PpIX) induced by 5-aminolevulinic acid (ALA) or its derivatives is a modification
of this treatment modality with successful application in dermatology. However, the mechanism of cell destruction by ALA-PDT
has not been elucidated. In this study a human T-cell lymphoma Jurkat cell line was treated with PDT using hexaminolevulinate
(HAL, hexylester of ALA). Four hours following treatment nearly 80% of the cells exhibited typical apoptotic features. Mitochondrial
pro-apoptotic proteins were evaluated by Western blots in subcellular fractionated samples. PDT caused cytosolic translocation
of cytochrome c and nuclear redistribution of apoptosis-inducing factor (AIF), but the release of mitochondrial Smac/DIABLO, Omi/HtrA2 and
EndoG was not observed. The release of cytochrome c was followed by the cleavage of caspase-9 and caspase-3 as well as its downstream substrates, together with oligonucleosomal
DNA fragmentation. The pan-caspases inhibitor, z-VAD.fmk, prevented oligonucleosomal DNA fragmentation, but failed to inhibit
PDT-mediated apoptosis. The apoptotic induction by AIF-mediated caspase-independent pathway was also found after HAL-PDT with
large-scale DNA fragmentation in the presence of z-VAD.fmk. These results demonstrate that cytochrome c-mediated caspase-dependent pathway and AIF-induced caspase-independent pathway are simultaneously involved in the apoptotic
induction by PDT. When the cytochrome c-induced caspase-dependent pathway is blocked, the cells go into apoptosis via AIF-mediated pathway, clearly demonstrating
that the cytochrome c-mediated caspase-dependent pathway is not required for such apoptotic induction. This finding may have an impact on improved
PDT effectiveness. 相似文献
15.
Lafont E Dupont R Andrieu-Abadie N Okazaki T Schulze-Osthoff K Levade T Benoist H Ségui B 《Biochimica et biophysica acta》2012,1821(4):684-693
Ceramide, a biologically active sphingolipid in cell death signaling, accumulates upon CD95L treatment, concomitantly to apoptosis induction in Jurkat leukemia T cells. Herein, we show that ceramide did not increase in caspase-8 and -10-doubly deficient Jurkat cells in response to CD95L, indicating that apical caspases are essential for CD95L-triggered ceramide formation. Jurkat cells are typically defined as type 2 cells, which require the activation of the mitochondrial pathway for efficient apoptosis induction in response to CD95L. Caspase-9-deficient Jurkat cells significantly resisted CD95L-induced apoptosis, despite ceramide accumulation. Knock-down of sphingomyelin synthase 1, which metabolizes ceramide to sphingomyelin, enhanced (i) CD95L-triggered ceramide production, (ii) cytochrome c release from the mitochondria and (iii) caspase-9 activation. Exogenous ceramide-induced caspase-3 activation and apoptosis were impaired in caspase-9-deficient Jurkat cells. Conversely, caspase-9 re-expression in caspase-9-deficient Jurkat cells restored caspase-3 activation and apoptosis upon exogenous ceramide treatment. Collectively, our data provide genetic evidence that CD95L-triggered endogenous ceramide increase in Jurkat leukemia T cells (i) is not a mere consequence of cell death and occurs mainly in a caspase-9-independent manner, (ii) is likely involved in the pro-apoptotic mitochondrial pathway leading to caspase-9 activation. 相似文献
16.
Munehisa Yabuki Ken Tsutsui Alan A. Horton Tamotsu Yoshioka Kozo Utsumi 《Free radical research》2013,47(6):507-514
Nitric oxide (NO) from (Z)-1-[N-(2-aminoethyl)-N-(2-ammonioethyl)amino]diazen-1-ium-1,2-diolate (NOC-18) induces apoptosis in human leukemia HL-60 cells. This effect was prevented by the pan-caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl ketone (Z-VAD-FMK), thereby implicating caspase activity in the process. NOC-18 treatment resulted in the activation of several caspases including caspase-3, -6, -8, and -9(-like) activities and the degradation of several caspase substrates such as nuclear lamins and SP120 (hnRNP-U/SAF-A). Moreover, release of cytochrome c from mitochondria was also observed during NOC-18-induced apoptosis. This change was substantially prevented by Z-VAD-FMK, thereby suggesting that the released cytochrome c might function not only as an initiator but also as an amplifier of the caspase cascade. Bid, a death agonist member of the Bcl-2 family, was processed by caspases following exposure of cells to NOC-18, supporting the above notion. Thus, NO-mediated apoptosis in HL-60 cells involves a caspase/cytochrome c-dependent mechanism. 相似文献
17.
Martinez-Caballero S Dejean LM Jonas EA Kinnally KW 《Journal of bioenergetics and biomembranes》2005,37(3):155-164
Permeabilization of the mitochondrial outer membrane is a crucial event during apoptosis. It allows the release of proapoptotic factors, like cytochrome c, from the intermembrane space, and represents the commitment step in apoptosis. The mitochondrial apoptosis-induced channel, MAC, is a high-conductance channel that forms during early apoptosis and is the putative cytochrome c release channel. Unlike activation of the permeability transition pore, MAC formation occurs without loss of outer membrane integrity and depolarization. The single channel behavior and pharmacology of reconstituted MAC has been characterized with patch-clamp techniques. Furthermore, MAC’s activity is compared to that detected in mitochondria inside the cells at the time cytochrome c is released. Finally, the regulation of MAC by the Bcl-2 family proteins and insights concerning its molecular composition are also discussed. 相似文献
18.
Basma H El-Refaey H Sgagias MK Cowan KH Luo X Cheng PW 《Journal of biomedical science》2005,12(6):999-1011
Summary Chemotherapy has been used for treatment of breast cancer but with limited success. We characterized the effects of bcl-2
antisense and cisplatin combination therapy in two human isogenic breast carcinoma cells p53(+)MCF-7 and p53(−)MCF-7/E6. The
transferrin-facilitated lipofection strategy we have developed yielded same transfection efficiency in both cells. Bcl-2 antisense
delivered with this strategy significantly induced more cell death, apoptosis, and cytochrome c release in MCF-7/E6 than in MCF-7, but did not affect Fas level in both cells and activated caspase-8 equally. Cisplatin
exerted same effects on cell viability and apoptosis in both cells, but released smaller amounts of cytochrome c while activated more caspase-8 in MCF-7/E6. The combination treatment yielded greater effects on cell viability, apoptosis,
cytochrome c release, and caspase-8 activation than individual treatments in both cells although p53(−) cells were more sensitive. The
potentiated activation of caspase-8 in the combination treatment suggested that caspase-8-mediated (but cytochrome c-independent) apoptotic pathway is the major contributor of the enhanced cell killing. Thus, bcl-2 antisense delivered with
transferrin-facilitated lipofection can achieve the efficacy of killing breast cancer cells and sensitizing them to chemotherapy.
Bcl-2 antisense and cisplatin combination treatment is a potentially useful therapeutic strategy for breast cancer irrespective
of p53 status.
Hesham Basma and Hesham El-Refaey contributed equally 相似文献
19.
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
20.
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