Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana 47907-1333
Received April 8, 2003; accepted May 19, 2003
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ABSTRACT |
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Key Words: cyanide; apoptosis; Bax; p38 MAP kinase; cytochrome c.
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INTRODUCTION |
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Bax, a proapoptotic member of the Bcl-2 family, normally resides in the cytosol and translocates to mitochondria in response to a variety of apoptotic stimuli (Khaled et al., 1999; Murphy et al., 1999
; Putcha et al., 1999
; Wolter et al., 1997
). In mitochondria, Bax exerts a proapoptotic action by disrupting mitochondrial membrane potential, leading to release of cytochrome c, and by heterodimerizing with antiapoptotic Bcl-2 proteins to neutralize their actions. The conformation of Bax is critical for its subcellular location. A single transmembrane domain at the carboxy terminus of Bax is responsible for its membrane insertion (Goping et al., 1998
; Nechushtan et al., 1999
). Under normal conditions, this transmembrane domain is masked by the amino terminus domain. Deletion of N-terminus or point mutations in the C-terminus domain can target Bax to mitochondria, suggesting that a specific Bax conformation regulates mitochondrial docking. Upstream events that induce a Bax conformational change are still unclear. Recent studies suggest that caspase activation, Bid association, and p38 mitogen-activated protein (MAP) kinase initiate changes in Bax conformation, followed by mitochondrial translocation (Desagher et al., 1999
; Ghatan et al., 2000
; Putcha et al., 1999
).
p38 MAP kinase is a member of the MAP kinase family that is involved in the cell death cascade and is activated by phosphorylation on Thr-180 and Tyr-182 (Noh et al., 2000; Yamagishi et al., 2001
). Activation of p38 MAP kinase has been observed in Alzheimers disease (Zhu et al., 2000
), in transient forebrain ischemia (Takagi et al., 2000
), and in apoptosis induced by various stimuli, including hypoxia (Chae et al., 2001
), glutamate (Kawasaki et al., 1997
), and nerve growth factor (NGF) withdrawal (De Zutter and Davis, 2001
), and low potassium (Yamagishi et al., 2001
). p38 MAP kinase appears to have multiple targets in the apoptotic pathway. In NGF withdrawal-induced apoptosis in PC12 cells, the kinase induces expression of monoamine oxidase (MAO) (De Zutter and Davis, 2001
). In nitric oxide (NO)-induced neuronal apoptosis, p38 MAP kinase initiates Bax translocation, followed by caspase activation (Ghatan et al., 2000
).
Previous studies show that in cerebellar granule and cortical cells, cyanide-mediated activation of the N-methyl-D-aspartate (NMDA) glutamatergic receptor activation leads to a marked elevation of cytosolic-free Ca2+ and reactive oxygen species generation, which in turn are intracellular initiators of apoptosis (Shou et al., 2000; Sun et al., 1997
). It is conceivable that p38 MAP kinase might mediate Bax translocation and the subsequent activation of the apoptotic cascade. In this study, the relationship of p38 MAP kinase activation with Bax translocation and the subsequent release of cytochrome c from mitochondria during cyanide-induced apoptosis was determined.
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MATERIALS AND METHODS |
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Subcellular fractionation.
Subcellular fractionation was performed as described by Desagher et al. (1999). Cortical cells were harvested in Tris-buffered saline (TBS) and centrifuged at 500 x g for 5 min. Cell pellets were resuspended in isotonic mitochondrial buffer (210 mM mannitol, 70 mM sucrose, 1 mM EDTA, and 10 mM N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid [HEPES], pH 7.5) supplemented with 0.04% digitonin, 1 mM dithiothreitol (DTT), and a protease inhibitor cocktail (Boehringer Mannheim, Indianapolis, IN). Samples were centrifuged at 500 x g for 5 min at 4°C to remove intact cells and nuclei. Resulting supernatants were further centrifuged at 10,000 x g for 30 min at 4°C to obtain the heavy membrane pellet (HM) enriched for mitochondria. The 10,000 x g supernatant was used as crude cytosol, and the HM pellet was resuspended in 50 µl MB buffer. Sixty micrograms of the cytosolic and 30 µg of the HM fraction were separated in 12% sodium dodecyl sulfate (SDS)-polyacrylamide gel, transferred to a polyvinylidene difluoride (PVDF) membrane (Biorad Laboratories, Hercules, CA), and detected with an anti-Bax monoclonal antibody for Bax diluted 1:100 in phosphate-buffered saline (PBS; Santa Cruz Biotechnology, Santa Cruz, CA).
Western blot analysis.
After different treatments, cortical cells were harvested in PBS and centrifuged at 500 x g. Cell pellets were resuspended in lysis buffer (25 mM Tris, pH 7.5, 1 mM ethylene glycol tetraacetic acid (EGTA), 2 mM EDTA, 50 mM sodium fluoride (NaF), 1 mM sodium orthovanadate (Na3VO4), 0.2% Nonidet P40 (NP40), 0.1 mM phenylmethylsulfonyl fluoride (PMSF), 1 mM dithiothreitol (DTT), 10 µg/ml aprotinin, 10 µg/ml leupeptin, 10 µg/ml pepstatin) and incubated on ice for 30 min. The lysates were centrifuged at 10,000 x g for 15 min. Supernatants containing 100 µg protein were boiled in Laemmlis sampling buffer, then electrophoresed in 12% SDSpolyacrylamide gel electrophoresis (PAGE) and transferred to PVDF membrane. After blocking with PBS containing 5% nonfat dry milk and 0.1% Tween 20, the membrane was probed with anti-phospho-p38 MAP kinase (Tyr 182) antibody (New England Biolab, Beverly, MA) and anti-p38 MAP kinase antibody (New England Biolab) diluted 1:100 in PBS. Reactions were detected with the fluorescein-linked antimouse Ig (second antibody) conjugated to horseradish peroxidase using a Storm 860 fluorescence-PhosphorImager (Molecular Dynamics, Sunnyvale, CA). Densitometry analysis was performed using the ImageQuant software (Molecular Dynamics). To determine whether caspase-3 was activated after inhibition of p38 MAP kinase, cells were pretreated with SB203580 (p38 MAP kinase inhibitor), followed by KCN (300 µM). Whole cell lysates were subjected to SDSPAGE, and blots were probed with anticaspase-3 antibody (Santa Cruz Biotechnology), which binds both procaspase and cleaved (activated) product. Procaspase-3 conversion to caspase-3 was used as an index of caspase activity (Shou et al., 2002).
Immunocytochemistry.
For immunocytochemical analysis, cortical neurons were grown on poly-L-lysine-coated coverslips. After cyanide treatment, cells were labeled with 500 nM mitotracker red (Molecular Probes, Eugene, OR) for 30 min at 37°C. After three washes with PBS, cells were fixed with 4% paraformaldehyde for 15 min and permeabilized with 0.2% Triton X-100 for 30 min at room temperature. Cultures were then washed with PBS and exposed to blocking solution (5% goat serum in PBS). After PBS washing, cells were incubated with mouse monoclonal anti-Bax antibody (1:100 diluted in PBS) at room temperature for 3 h. Cells were washed twice in PBS and incubated with Alexa Fluor 488-conjugated goat antimouse secondary antibody (Molecular Probes) for 1 h at room temperature in the dark. Coverslips were then mounted onto glass slides and examined by confocal microscopy.
Internucleosomal DNA fragmentation.
Genomic DNA was extracted according to the protocol described previously (Shou et al., 2000). Cells were collected in PBS and lysed in lysis buffer (10 mM Tris-HCl, pH 7.4; 10 mM EDTA; 0.5% SDS) with RNase A (final concentration 100 µg/ml) for 1 h at 37°C. Then 100 µg/ml proteinase K was added and incubated for 4 h at 50°C. DNA was precipitated with 0.1 volume of 3 M sodium acetate (pH 5.2) and 2.5 volume of precooled ethanol, then resuspended in Tris-EDTA buffer. Ten micrograms of DNA sample were separated on a 1.2% agarose gel containing 0.5 µg/ml ethidium bromide for 2 h and visualized under ultraviolet light.
Statistics.
Each experiment was repeated a minimum of three times, and data were expressed as mean ± SEM. One-way ANOVA with a Tukey-Kramer procedure for multiple comparisons was used to examine the statistical differences between treatments. Differences were considered as significant at p < 0.05.
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RESULTS |
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DISCUSSION |
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Cyanide enhances NMDA receptor functions to initiate influx of Ca2+ (Patel et al., 1992; Sun et al., 1997
) and mobilizes intracellular calcium stores (Yang et al., 1997
). In cultured neurons, cyanide-induced cytotoxicity is linked to the NMDA receptor-mediated rise in cytosolic Ca2+ that in turn activates a series of biochemical reactions, leading to generation of reactive oxygen species (ROS) and NO. From this study, it is concluded that the apoptotic initiation stimuli produced by cyanide are elevation of cytosolic Ca2+ following NMDA receptor activation and generation of excess intracellular ROS. These stimuli appear to initiate p38 MAP kinase activation, which in turn mediates Bax translocation, followed by cytochrome c release and execution of apoptosis.
The Bcl-2 gene family regulates mitochondria-mediated apoptosis (Gross et al., 1999; Shinoura et al., 1999
). The antiapoptotic protein regulators Bcl-2 and Bcl-XL reside in the outer mitochondrial membrane and inhibit cytochrome c release. Increasing Bcl-2 expression confers resistance to apoptosis, whereas decreasing expression enhances apoptotic cell death. Proapoptotic Bcl-2 family members include Bax, Bad, Bid, Bcl-XS, and Bim proteins that translocate from cytoplasm to mitochondria on an apoptotic signal to stimulate release of cytochrome c. Bax expression is regulated by the redox-sensitive transcription factor NF
B; oxidative stress increases Bax expression via NF
B activation and produces a proapoptotic state (Shou et al., 2002
; Wiu et al., 2001
). The ratio of Bax/Bcl-2 regulates the cellular state, and death-promoting pathways are activated if the ratio increases. In the case of cyanide, cellular Bcl-2 levels influence the apoptotic response (Jensen et al., 2002
) and overexpression of Bcl-2 protected hypothalamic cells, preventing changes in the
m (Myers et al., 1995
; Shimizu et al., 1996
). We have demonstrated that regulation of the Bax protein family expression level has a marked influence on cyanide-induced apoptosis in cortical cells (Shou et al., 2002
). Cyanide produces an NF
B-mediated upregulation of Bcl-XS and Bax expression, which in turn stimulates cytochrome c release from mitochondria, followed by caspase-3 activation (Shou et al., 2002
; Wiu et al., 2001
). Inhibition of NF
B activation with SN50 (a specific inhibitor) or kB decoy DNA suppressed upregulation of Bcl-XS and Bax and decreased apoptosis. In the presence of cyanide, increased cytosolic Ca2+ is a signal that initiates Bad (proapoptotic Bcl-2 family member) translocation to mitochondria, thus linking the apoptotic response to Ca2+ influx (Shou et al., 2003, unpublished data).
Bax is a proapoptotic member of the Bcl-2 protein family involved in regulating cytochrome c release in apoptotic cell death. Overexpression of Bax initiates cytochrome c release and subsequent cell death (Rosse et al., 1998). Addition of Bax to a cell-free system can induce cytochrome c release from isolated mitochondria (Jurgensmeier et al., 1998
). It has been proposed that Bax interacts with components of the mitochondria permeability transition (MPT) pore to promote opening of the pore, which ultimately causes outer mitochondria membrane rupture and cytochrome c release (Marzo et al., 1998
; Shimizu et al., 1999
). Alternatively, Bax could form a channel in the mitochondrial membrane that directly releases cytochrome c. The three-dimensional structure of Bcl-2 family members bears a striking structural similarity to the pore-forming domains of certain bacterial toxins (Muchmore et al., 1996
). Moreover, Bax has pore-forming capability in vivo (Antonsson et al., 1997
).
Under normal, basal conditions, Bax resides mainly in the cytosol, and in order for Bax to induce cytochrome c release, an association of Bax with the mitochondrial membrane is necessary. Upon activation of extracellular membrane receptors or intracellular targets by an apoptotic stimulus, translocation of Bax to the mitochondrion is initiated (Murphy et al., 1999; Wolter et al., 1997
). In this study, cyanide initiated a subcellular cascade of reactions, resulting in Bax translocation to the mitochondrion prior to cytochrome c release. Double-immunofluorescence staining showed that Bax association with mitochondria is an initiating event for mitochondrial release of cytochrome c and subsequent caspase activation.
The signal that induces movement of Bax from the cytosol to mitochondria following an apoptotic stimulus may involve a conformational change to expose a masked C-terminal transmembrane domain of the protein (Goping et al., 1998; Nechushtan et al., 1999
). The conformational change may be triggered by a rise in intracellular pH (Khaled et al., 1999
) or by Bid (Eskes et al., 2000
). Alternatively, phosphorylation of critical amino acid residues in either the N- or C-terminal domains of Bax may also induce a conformational change. p38 MAP kinase may mediate this phosphorylation. p38 MAP kinase has been reported to regulate Bax translocation in apoptosis induced by NO (Ghatan et al., 2000
) and by T cell receptor stimulation (Yoshino et al., 2001
). This study shows that cyanide-induced p38 MAP kinase activation is likely an upstream signal for Bax translocation.
p38 MAP kinase is a member of the stress-activated protein kinase family. It is phosphorylated in numerous cell types following treatment with a variety of toxic agents, and its activation is associated with induction of apoptosis (De Zutter and Davis, 2001; Noh, 2000
; Yamagishi et al., 2001
). In this study, it was shown that p38 MAP kinase was activated by the intracellular Ca2+ overload resulting from cyanide-induced NMDA receptor activation. This is supported by the observation that the NMDA receptor antagonist MK801 and the intracellular Ca2+ chelator BAPTA attenuated cyanide-induced p38 MAP kinase activation. These findings are consistent with previous observations showing that glutamate activates p38 MAP kinase in cerebellar granule neurons (Kawasaki et al., 1997
). In addition to intracellular Ca2+ overload, it appears that oxidative stress produced by cyanide also contributed to p38 MAP kinase activation, because the antioxidants PBN and NAC inhibited cyanide-induced p38 MAP kinase activation.
In summary, this study shows that in cyanide-induced apoptosis, p38 MAP kinase activation is upstream of Bax translocation. Association of Bax with the mitochondrion promotes cytochrome c release from the intermembrane space into the cytosol to execute apoptosis by activating the caspase cascade.
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ACKNOWLEDGMENTS |
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NOTES |
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REFERENCES |
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Chae, H. J., Kim, S. C., Han, K. S., Chae, S. W., An, N. H., Kim, H. M., Kim, H. H., Lee, Z. H., and Kim, H. R. (2001). Hypoxia induces apoptosis by caspase activation accompanying cytochrome c release from mitochondria in MC3T3E1 osteoblasts. p38 MAP kinase is related in hypoxia-induced apoptosis. Immunopharmacol. Immunotoxicol. 23, 133152.[CrossRef][ISI][Medline]
Desagher, S., Osen-Sand, A., Nichols, A., Eskes, R., Montessuit, S., Lauper, S., Maundrell, K., Antonsson, B., and Martinou, J. (1999). Bid-induced conformational change of Bax is responsible for mitochondrial cytochrome c release during apoptosis. J. Cell Biol. 144, 891901.
De Zutter, G. S., and Davis, R. J. (2001). Pro-apoptotic gene expression mediated by the p38 mitogen-activated protein kinase signal transduction pathway. Proc. Natl. Acad. Sci. U.S.A. 98, 61686173.
Eskes, R., Desagher, S., Antonsson, B., and Martinou, J. C. (2000). Bid induces the oligomerization and insertion of Bax into the outer mitochondrial membrane. Mol. Cell Biol. 20, 929935.
Finucane, D. M., Bossy-Wetzel, E., Waterhouse, N. J., Cotter, T. G., and Green, D. R. (1999). Bax-induced caspase activation and apoptosis via cytochrome c release from mitochondria is inhibitable by Bcl-XL. J. Biol. Chem. 274, 22252233.
Ghatan, S., Larner, S., Kinoshita, Y., Hetman, M., Patel, L., Xia, Z., Youle, R. J., and Morrison, R. S. (2000). p38 MAP kinase mediates Bax translocation in nitric oxide-induced apoptosis in neurons. J. Cell Biol. 150, 335347.
Goping, I. S., Gross, A., Lavoie, J. N., Nguyen, M., Jemmerson, R., Roth, K., Korsmeyer, S. J., and Shore, G. C. (1998). Regulated targeting of Bax to mitochondria. J. Cell Biol. 143, 207215.
Gross, A., McDonnell, J. M., and Korsmeyer, S. J. (1999). Bcl-2 family members and the mitochondria in apoptosis. Genes Dev. 13, 18991911.
Jensen, M. S., Ahlemeyer, R. A., Thakur, P., Mennel, H-D., and Krieglstein, J. (2002). Preconditioning-induced protection against cyanide-induced neurotoxicity is mediated by preserving mitochondrial function. Neurochem. Int. 40, 285293.[CrossRef][ISI][Medline]
Jurgensmeier, J. M., Xie, Z., Deveraux, Q., Ellerby, L., Bredesen, D., and Reed, J. C. (1998). Bax directly induces release of cytochrome c from isolated mitochondria. Proc. Natl. Acad. Sci. U.S.A. 95, 49975002.
Kawasaki, H., Morooka, T., Shimohama, S., Kimura, J., Hirano, T., Gotoh, Y., and Nishida, E. (1997). Activation and involvement of p38 mitogen-activated protein kinase in glutamate-induced apoptosis in rat cerebellar granule cells. J. Biol. Chem. 272, 1851818521.
Khaled, A. R., Kim, K., Hofmeister, R., Muegge, K., and Durum, S. (1999). Withdrawal of IL-7 induces Bax translocation from cytosol to mitochondria through a rise in intracellular pH. Proc. Natl. Acad. Sci. U.S.A. 96, 1447614481.
Marzo, I., Brenner, C., Zamzami, N., Jurgensmeier, J. M., Susin, S. A., Vieira, H. L., Prevost, M. C., Xie, Z., Matsuyama, S., Reed, J. C., and Kroemer, G. (1998). Bax and adenine nucleotide translocator cooperate in the mitochondrial control of apoptosis. Science 281, 20272031.
Mills, E. M., Gunasekar, P. G., Borowitz, J. L., and Isom, G. E. (1999). Cyanide-induced neurodegeneration involves different susceptibility of brain areas and different modes of cell death. Toxicol. Appl. Pharmacol. 156, 616.[CrossRef][ISI][Medline]
Muchmore, S. W., Sattler, M., Hiang, H., Meadows, R. P., Harlan, J. E., Yoon, H. S., Nettesheim, D., Chang, B. S., Thompson, C. B., Wong, S., et al. (1996). X-ray and NMR structure of human Bcl-XL, an inhibitor of programmed cell death. Nature 381, 335341.[CrossRef][ISI][Medline]
Murphy, K. M., Streips, U. N., and Lock, R. B. (1999). Bax membrane insertion during Fas (CD95)-induced apoptosis precedes cytochrome c release and is inhibited by Bcl-2. Oncogene 18, 59915999.[CrossRef][ISI][Medline]
Myers, K. M., Fiskum, G., Liu, Y., Simmens, S. J., Bresdesen, D. E., and Murphy, A. N. (1995). Bcl-2 protects neural cells from cyanide/aglycemia-induced lipid oxidation, mitochondrial injury, and loss of viability. J. Neurochem. 65, 24322440.[ISI][Medline]
Narita, M., Shinizu, S., Ito, T., Chittenden, T., Lutz, R. J., Matsuda, H., and Tsujimoto, Y. (1998). Bax interacts with the permeability transition pore to induce permeability transition and cytochrome c release in isolated mitochondria. Proc. Natl. Acad. Sci. U.S.A. 95, 1468114686.
Nechushtan, A., Smith, C. L., Hsu, Y., and Youle, R. J. (1999). Conformation of the Bax C-terminus regulates subcellular location and cell death. EMBO J. 18, 23302341.
Noh, J. S., Kang, H. J., Kim, E. Y., Sohn, S., Chung, Y. K., Kim, S. U., and Gwag, B. J. (2000). Haloperidol-induced neuronal apoptosis: Role of p38 and c-Jun-NH(2)-terminal protein kinase. J. Neurochem. 75, 23272334.[CrossRef][ISI][Medline]
Patel, M. N., Yim, G. K. W., and Isom, G. E. (1992). Blockade of N-methyl-D-aspartate receptors prevent cyanide-induced neuronal injury in primary hippocampal cultures. Toxicol. Appl. Pharmacol. 115, 124129.[CrossRef][ISI][Medline]
Prabhakaran, K., Li, L., Borowitz, J. L., and Isom, G. E. (2002). Cyanide induces different modes of death in cortical and mesencephalon cells. J. Pharmacol. Exp. Ther. 303, 510519.
Putcha, G. V., Deshmukl, M., and Johnson, E. M. (1999). Bax translocation is a critical event in neuronal apoptosis: Regulation by neuroprotectants Bcl-2 and caspases. J. Neurosci. 19, 74767485.
Rosse, T., Olivier, R., Monney, L., Rager, M., Conus, S., Fellay, L., Jansen, B., and Borner, C. (1998). Bcl-2 prolongs cell survival after Bax-induced release of cytochrome c. Nature 391, 496499.[CrossRef][ISI][Medline]
Shimizu, S., Eguchi, Y., Kamuke, W., Waguri, S., Zuchiyama, Y., Matsuda, H., and Tsujimoto, Y. (1996). Bcl-2 block loss of mitochondrial membrane potential while ICE inhibitors act as a different step during inhibition of death induced respiratory chain inhibitors. Oncogene 13, 2129.[ISI][Medline]
Shimizu, S., Narita, M., and Tsujimoto, Y. (1999). Bcl-2 family proteins regulate the release of apoptogenic cytochrome c by the mitochondrial channel VDAC. Nature 399, 483487.[CrossRef][ISI][Medline]
Shinoura, N., Yoshida, Y., Asai, A., Kirino, T., and Hamada, H. (1999). Relative level of expression of Bax and Bcl-XL determines the cellular fate of apoptosis/necrosis induced by the overexpression of Bax. Oncogene 18, 57035713.[CrossRef][ISI][Medline]
Shou, Y., Gunasekar, P. G., Borowitz, J. L., and Isom, G. E. (2000). Cyanide-induced apoptosis involves oxidative-stress-activated NF-B in cortical neurons. Toxicol. Appl. Pharmacol. 164, 196205.[CrossRef][ISI][Medline]
Shou, Y., Li, N., Li, L., Borowitz, J. L., and Isom, G. E. (2002). NF-B-mediated upregulation of Bcl-XS and Bax contributes to cyotchrome c release in cyanide-induced apoptosis. J. Neurochem. 81, 842852.[CrossRef][ISI][Medline]
Sun, P., Rane, S. G., Gunasekar, P. G., Borowitz, J. L., and Isom, G. E. (1997). Modulation of the NMDA receptor by cyanide: Enhancement of receptor-mediated responses. J. Pharmacol. Exp. Ther. 280, 13411348.
Takagi, Y., Nozaki, K., Sugino, T., Hattori, I., and Hashimoto, N. (2000). Phosphorylation of c-Jun NH(2)-terminal kinase and p38 mitogen-activated protein kinase after transient forebrain ischemia in mice. Neurosci. Lett. 294, 117120.[CrossRef][ISI][Medline]
Wiu, J., Grafe, M. R., Schmura, S. M., Glasgow, J. N., Kent, T. A., Rassin, D. K., and Perez-Polo, J. R. (2001). Differential NF-B regulation of bcl-x gene expression in hippocampus and basal forebrain in response to hypoxia. J. Neurosci. Res. 64, 223234.[CrossRef][ISI][Medline]
Wolter, K. G., Hsu, Y., Smith, C. L., Nechushtan, A., Xi, X., and Youle, R. J. (1997). Movement of Bax from the cytosol to mitochondria during apoptosis. J. Cell Biol. 139, 12811292.
Yamagishi, S., Yamada, M., Ishikawa, Y., Matsumoto, T., Ikeuchi, T., and Hatanaka, H. (2001). p38 mitogen-activated protein kinase regulates low potassium-induced c-Jun phosphorylation and apoptosis in cultured cerebellar granule neurons. J. Biol. Chem. 276, 51295133.
Yang, C. W., Borowitz, J. L., Gunasekar, P. G. and Isom, G. E. (1997). Cyanide stimulated inositol 1,4,5-triphosphate formation: An intracellular neurotoxic signaling cascade. J. Biochem. Toxicol. 11, 251256.[CrossRef]
Yin, X. M., Luo, Y., Cao, G., Bai, L., Pei, W., Kuharsky, D. K., and Chen, J. (2002). Bid-mediated mitochondrial pathway is critical to ischemic neuronal apoptosis and focal cerebral ischemia. J. Biol. Chem. 277, 4207442081.
Yoshino, T., Kishi, H., Nagata, T., Tsukada, K., Saito, S., and Muraguchi, A. (2001). Differential involvement of p38 MAP kinase pathway and Bax translocation in the mitochondrial-mediated cell death in TCR- and dexamethasone-stimulated thymocytes. Eur. J. Immunol. 31, 27022708.[CrossRef][ISI][Medline]
Zhu, X., Rottkamp, C. A., Boux, H., Takeda, A., Perry, G., and Smith, M. A. (2000). Activation of p38 kinase links tau phosphorylation, oxidative stress, and cell cycle-related events in Alzheimer disease. J. Neuropathol. Exp. Neurol. 59, 880888.[ISI][Medline]