scholarly journals Critical function of endogenous XIAP in regulating caspase activation during sympathetic neuronal apoptosis

2003 ◽  
Vol 163 (4) ◽  
pp. 789-799 ◽  
Author(s):  
Patrick Ryan Potts ◽  
Shweta Singh ◽  
Malia Knezek ◽  
Craig B. Thompson ◽  
Mohanish Deshmukh
Keyword(s):  
Cytochrome C ◽  
Mammalian Cells ◽  
Sympathetic Neurons ◽  
Caspase Activation ◽  
Cytochrome C Release ◽  
Critical Function ◽  
Apoptosis Protein ◽  
Induced Apoptosis ◽  
Necessary And Sufficient ◽  
Cytosolic Cytochrome

In sympathetic neurons, unlike most nonneuronal cells, growth factor withdrawal–induced apoptosis requires the development of competence in addition to cytochrome c release to activate caspases. Thus, although most nonneuronal cells die rapidly with cytosolic cytochrome c alone, sympathetic neurons are remarkably resistant unless they develop competence. We have identified endogenous X-linked inhibitor of apoptosis protein (XIAP) as the essential postcytochrome c regulator of caspase activation in these neurons. In contrast to wild-type neurons that are resistant to injection of cytochrome c, XIAP-deficient neurons died rapidly with cytosolic cytochrome c alone. Surprisingly, the release of endogenous Smac was not sufficient to overcome the XIAP resistance in sympathetic neurons. In contrast, the neuronal competence pathway permitted cytochrome c to activate caspases by inducing a marked reduction in XIAP levels in these neurons. Thus, the removal of XIAP inhibition appears both necessary and sufficient for cytochrome c to activate caspases in sympathetic neurons. These data identify a critical function of endogenous XIAP in regulating apoptosis in mammalian cells.

scholarly journals Reduced Apaf-1 levels in cardiomyocytes engage strict regulation of apoptosis by endogenous XIAP

2005 ◽  
Vol 171 (6) ◽  
pp. 925-930 ◽  
Author(s):  
Malia B. Potts ◽  
Allyson E. Vaughn ◽  
Holly McDonough ◽  
Cam Patterson ◽  
Mohanish Deshmukh
Keyword(s):  
Cytochrome C ◽  
Potent Inhibitor ◽  
Sympathetic Neurons ◽  
Striking Similarity ◽  
Inhibitor Of Apoptosis ◽  
Caspase Activation ◽  
Exact Function ◽  
Apoptosis Protein ◽  
Strict Regulation ◽  
Cytosolic Cytochrome

Overexpression studies have identified X-linked inhibitor of apoptosis protein (XIAP) as a potent inhibitor of caspases. However, the exact function of endogenous XIAP in regulating mammalian apoptosis is less clear. Endogenous XIAP strictly regulates cytochrome c–dependent caspase activation in sympathetic neurons but not in many mitotic cells. We report that postmitotic cardiomyocytes, unlike fibroblasts, are remarkably resistant to cytosolic microinjection of cytochrome c. The cardiomyocyte resistance to cytochrome c is mediated by endogenous XIAP, as XIAP-deficient cardiomyocytes die rapidly with cytosolic cytochrome c alone. Importantly, we found that cardiomyocytes, like neurons, have markedly reduced Apaf-1 levels and that this decrease in Apaf-1 is directly linked to the tight regulation of caspase activation by XIAP. These data identify an important function of XIAP in cardiomyocytes and point to a striking similarity in the regulation of apoptosis in postmitotic cells.

Resistance of leukemic cells to 2-chlorodeoxyadenosine is due to a lack of calcium-dependent cytochrome c release

Blood ◽  
2002 ◽  
Vol 99 (2) ◽  
pp. 655-663 ◽  
Author(s):  
Joya Chandra ◽  
Emma Mansson ◽  
Vladimir Gogvadze ◽  
Scott H. Kaufmann ◽  
Freidoun Albertioni ◽  
...  
Keyword(s):  
Cytochrome C ◽  
Dna Fragmentation ◽  
Cell Lines ◽  
Resistant Cell ◽  
Leukemic Cells ◽  
Caspase Activation ◽  
Cytochrome C Release ◽  
Deoxyguanosine Kinase ◽  
Induced Apoptosis ◽  
Resistant Cells

Abstract The purine nucleoside 2-chlorodeoxyadenosine (CdA) is often used in leukemia therapy. Its efficacy, however, is compromised by the emergence of resistant cells. In the present study, 3 CdA-resistant cell lines were generated and characterized. Their ability to accumulate 2-chloroadenosine triphosphate (CdATP) varied, reflecting differences in activities of deoxycytidine kinase (dCK) and deoxyguanosine kinase (dGK). Nonetheless, the selected lines were uniformly resistant to CdA-induced apoptosis, as assessed by caspase activation and DNA fragmentation. In contrast, cytosols from resistant cells were capable of robust caspase activation when incubated in the presence of cytochrome c and dATP. Moreover, replacement of dATP with CdATP also resulted in caspase activation in the parental and some of the resistant cell lines. Strikingly, CdA-induced decreases in mitochondrial transmembrane potential and release of cytochrome c from mitochondria were observed in the parental cells but not in any resistant lines. The lack of cytochrome c release correlated with an increased ability of mitochondria from resistant cells to sequester free Ca2+. Consistent with this enhanced Ca2+buffering capacity, an early increase in cytosolic Ca2+after CdA treatment of parental cells but not resistant cells was detected. Furthermore, CdA-resistant cells were selectively cross-resistant to thapsigargin but not to staurosporine- or Fas-induced apoptosis. In addition, CdA-induced caspase-3 activation and DNA fragmentation were inhibited by the Ca2+ chelator BAPTA-AM in sensitive cells. Taken together, the data indicate that the mechanism of resistance to CdA may be dictated by changes in Ca2+-sensitive mitochondrial events.

scholarly journals The role of cytochrome c in caspase activation in Drosophila melanogaster cells

2002 ◽  
Vol 156 (6) ◽  
pp. 1089-1098 ◽  
Author(s):  
Loretta Dorstyn ◽  
Stuart Read ◽  
Dimitrios Cakouros ◽  
Jun R. Huh ◽  
Bruce A. Hay ◽  
...  
Keyword(s):  
Cytochrome C ◽  
Mammalian Cells ◽  
Significant Proportion ◽  
Ectopic Expression ◽  
Caspase Activation ◽  
Cytochrome C Release ◽  
Cell Extracts ◽  
Effector Caspase ◽  
Drosophila Cells

The release of cytochrome c from mitochondria is necessary for the formation of the Apaf-1 apoptosome and subsequent activation of caspase-9 in mammalian cells. However, the role of cytochrome c in caspase activation in Drosophila cells is not well understood. We demonstrate here that cytochrome c remains associated with mitochondria during apoptosis of Drosophila cells and that the initiator caspase DRONC and effector caspase DRICE are activated after various death stimuli without any significant release of cytochrome c in the cytosol. Ectopic expression of the proapoptotic Bcl-2 protein, DEBCL, also fails to show any cytochrome c release from mitochondria. A significant proportion of cellular DRONC and DRICE appears to localize near mitochondria, suggesting that an apoptosome may form in the vicinity of mitochondria in the absence of cytochrome c release. In vitro, DRONC was recruited to a >700-kD complex, similar to the mammalian apoptosome in cell extracts supplemented with cytochrome c and dATP. These results suggest that caspase activation in insects follows a more primitive mechanism that may be the precursor to the caspase activation pathways in mammals.

scholarly journals Corrigendum to: Cytochrome c release and caspase activation in hydrogen peroxide- and tributyltin-induced apoptosis (FEBS 20394)

FEBS Letters ◽  
1998 ◽  
Vol 437 (1-2) ◽  
pp. 163-163 ◽  
Author(s):  
Hélène Stridh ◽  
Monica Kimland ◽  
Dean P. Jones ◽  
Sten Orrenius ◽  
Mark B. Hampton
Keyword(s):  
Hydrogen Peroxide ◽  
Cytochrome C ◽  
Caspase Activation ◽  
Cytochrome C Release ◽  
Induced Apoptosis

scholarly journals Polyamine depletion prevents camptothecin-induced apoptosis by inhibiting the release of cytochromec

2002 ◽  
Vol 282 (6) ◽  
pp. C1290-C1297 ◽  
Author(s):  
Qing Yuan ◽  
Ramesh M. Ray ◽  
Leonard R. Johnson
Keyword(s):  
Cytochrome C ◽  
Mammalian Cells ◽  
Caspase 3 ◽  
Intestinal Epithelial ◽  
Caspase 9 ◽  
Cytochrome C Release ◽  
Polyamine Synthesis ◽  
Antiapoptotic Proteins ◽  
Induced Apoptosis ◽  
Rate Limiting

C1297, 2002; 10.1152/ajpcell.00351.2001.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 cfrom mitochondria, and expression and translocation of Bcl-2 family proteins. We inhibited ornithine decarboxylase, the first rate-limiting enzyme in polyamine synthesis, with α-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-xL 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.

scholarly journals Death Commitment Point Is Advanced by Axotomy in Sympathetic Neurons

2000 ◽  
Vol 150 (4) ◽  
pp. 741-754 ◽  
Author(s):  
Graham C. Fletcher ◽  
Luzheng Xue ◽  
Shareta K. Passingham ◽  
Aviva M. Tolkovsky
Keyword(s):  
Protein Synthesis ◽  
Cytochrome C ◽  
Neuronal Death ◽  
Sympathetic Neurons ◽  
Membrane Integrity ◽  
Erk Signaling ◽  
Receptor Signaling ◽  
Caspase Inhibitor ◽  
Caspase Activation ◽  
Cytosolic Cytochrome

Axotomized neurons have several characteristics that are different from intact neurons. Here we show that, unlike established cultures, the axotomized sympathetic neurons deprived of NGF become committed to die before caspase activation, since the same proportion of NGF-deprived neurons are rescued by NGF regardless of whether caspases are inhibited by the pan-caspase inhibitor Boc-Asp(O-methyl)-CH2F (BAF). Despite prolonged Akt and ERK signaling induced by NGF after BAF treatment has prevented death, the neurons fail to increase protein synthesis, recover ATP levels, or grow. Within 3 d, all the mitochondria disappear without apparent removal of any other organelles or loss of membrane integrity. Although NGF does rescue intact BAF-treated 6-d cultures after NGF deprivation, rescue by NGF fails when these neurons are axotomized before NGF deprivation and BAF treatment. Moreover, cytosolic cytochrome c rapidly kills axotomized neurons. We propose that axotomy induces signals that make sympathetic neurons competent to die prematurely. NGF cannot repair these NGF-deprived, BAF-treated neurons because receptor signaling (which is normal) is uncoupled from protein renewal, and the mitochondria (which are damaged) go on to be eliminated. Hence, the order of steps underlying neuronal death commitment is mutable and open to regulation.

Cytochrome c release and caspase activation during menadione-induced apoptosis in plants

FEBS Letters ◽  
1999 ◽  
Vol 462 (3) ◽  
pp. 317-321 ◽  
Author(s):  
Ying-Li Sun ◽  
Yun Zhao ◽  
Xia Hong ◽  
Zhong-He Zhai
Keyword(s):  
Cytochrome C ◽  
Caspase Activation ◽  
Cytochrome C Release ◽  
Induced Apoptosis

scholarly journals Apoptosome-deficient Cells Lose Cytochrome c through Proteasomal Degradation but Survive by Autophagy-dependent Glycolysis

2008 ◽  
Vol 19 (8) ◽  
pp. 3576-3588 ◽  
Author(s):  
Elisabetta Ferraro ◽  
Angela Pulicati ◽  
Maria Teresa Cencioni ◽  
Mauro Cozzolino ◽  
Francesca Navoni ◽  
...  
Keyword(s):  
Cytochrome C ◽  
Proteasomal Degradation ◽  
Pharmacological Intervention ◽  
Caspase Activation ◽  
Cytochrome C Release ◽  
Atp Production ◽  
Embryonic Origin ◽  
Autophagy Pathway ◽  
Mitochondrial Permeabilization ◽  
Cytosolic Cytochrome

Cytochrome c release from mitochondria promotes apoptosome formation and caspase activation. The question as to whether mitochondrial permeabilization kills cells via a caspase-independent pathway when caspase activation is prevented is still open. Here we report that proneural cells of embryonic origin, when induced to die but rescued by apoptosome inactivation are deprived of cytosolic cytochrome c through proteasomal degradation. We also show that, in this context, those cells keep generating ATP by glycolysis for a long period of time and that they keep their mitochondria in a depolarized state that can be reverted. Moreover, under these conditions, such apoptosome-deficient cells activate a Beclin 1–dependent autophagy pathway to sustain glycolytic-dependent ATP production. Our findings contribute to elucidating what the point-of-no-return in apoptosis is. They also help in clarifying the issue of survival of apoptosome-deficient proneural cells under stress conditions. Unraveling this issue could be highly relevant for pharmacological intervention and for therapies based on neural stem cell transfer in the treatment of neurological disorders.

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