451
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Affiliation(s)
- J P Kehrer
- Division of Pharmacology and Toxicology, College of Pharmacy, University of Texas at Austin, Austin, Texas 78712-1074, USA.
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452
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Kuninaka S, Ichinose Y, Koja K, Toh Y. Suppression of manganese superoxide dismutase augments sensitivity to radiation, hyperthermia and doxorubicin in colon cancer cell lines by inducing apoptosis. Br J Cancer 2000; 83:928-34. [PMID: 10970696 PMCID: PMC2374675 DOI: 10.1054/bjoc.2000.1367] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Increased expression of manganese superoxide dismutase (Mn-SOD), one of the mitochondrial enzymes involved in the redox system, has been shown to diminish the cytotoxic effects of several anti-cancer modalities, including tumour necrosis factor-alpha, ionizing radiation, certain chemotherapeutic agents and hyperthermia. We asked if Mn-SOD is a potential target to augment the sensitivity of cancer cells to various anti-cancer treatments and for this we established stable Mn-SOD antisense RNA expressing cell clones from two human colon cancer cell lines, HCT116 (p53 wild-type) and DLD1 (p53 mutant-type). Suppression of Mn-SOD in HCT116 was accompanied by an increased sensitivity to radiation, hyperthermia and doxorubicin, as compared with findings in controls. The mitochondrial permeability transition, as measured by a decrease of the mitochondrial transmembrane potential was more intensely induced by radiation in HCT116 antisense clones than in the control, an event followed by a greater extent of DNA fragmentation. Apoptosis was also induced by hyperthermia more intensely in HCT116 antisense clones than in the control. On the other hand, DLD1 antisense clones did not exhibit any enhancement of sensitivity to any of these treatments. These data support the possibility that inhibition of Mn-SOD activity renders colon cancer cells with wild-type p53 susceptible to apoptosis induced by radiation, hyperthermia and selected anti-cancer drugs. Therefore, we suggest that Mn-SOD could be a target molecule to overcome the resistance to anti-cancer treatments in some colon cancer cells carrying wild-type p53.
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Affiliation(s)
- S Kuninaka
- Clinical Research Institute, Department of Chest Surgery, Gastroenterologic Surgery, National Kyushu Cancer Center, Notame 3-1-1, Minami-ku, Fukuoka, 811-1395, Japan
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453
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Abstract
Atovaquone is a broad-spectrum antiparasitic agent active against malaria, Pneumocystis carinii pneumonia, toxoplasmosis and babesiosis. When used as a single agent, resistance to atovaquone arose rapidly in falciparum malaria, requiring the development of a new antimalarial drug combination of atovaquone and proguanil. Recent laboratory investigations have provided insights into the mode of atovaquone action, and identified the molecular basis for the resistance development. Mutations within a catalytic domain of the cytochrome bc(1)complex present within the parasite mitochondrial inner membrane were shown to be responsible for atovaquone resistance. Here, we review these studies and propose a mechanism by which atovaquone resistance may arise quickly in malaria parasites. Copyright 2000 Harcourt Publishers Ltd.
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Affiliation(s)
- Akhil B. Vaidya
- Department of Microbiology and Immunology, MCP Hahnemann University, Philadelphia, USA
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454
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Kahlos K, Soini Y, Pääkkö P, Säily M, Linnainmaa K, Kinnula VL. Proliferation, apoptosis, and manganese superoxide dismutase in malignant mesothelioma. Int J Cancer 2000; 88:37-43. [PMID: 10962437 DOI: 10.1002/1097-0215(20001001)88:1<37::aid-ijc6>3.0.co;2-3] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Proliferation and apoptotic indices of tumour cells may have important prognostic significance. Manganese superoxide dismutase (MnSOD), an important anti-oxidant enzyme, has been shown to decrease proliferation of malignant cells transfected with the MnSOD gene. The aim of the present study was to investigate the indices of cell proliferation and apoptosis and their prognostic significance in human mesothelioma and to assess the effect of MnSOD on the proliferation and apoptosis of the mesothelioma cells expressing high constitutive MnSOD activity. Tissue sections from 35 subjects with malignant pleural mesothelioma were studied for cell proliferation by Ki-67 immunohistochemistry and for apoptosis by the TUNEL assay. In additional experiments, 2 mesothelioma cell lines expressing either low (M14K) or high (M38K) MnSOD levels were assessed for proliferative and apoptotic responses to epirubicin. The median proliferation and apoptotic indices of the mesothelioma tissue were 8.2% and 0.75%, respectively. Patients with a high proliferation (>8%) or apoptotic index (>0.75%) showed a worse prognosis (p < 0.001). MnSOD expression was inversely correlated with cell proliferation (p = 0.02). Our cell line experiments indicated that cells expressing high MnSOD levels were more resistant to apoptosis and showed lower proliferation when exposed to epirubicin in vitro. These findings show that high proliferation and apoptosis are associated with a poor prognosis of mesothelioma and that a high MnSOD level is associated with low proliferation of tumour cells. Furthermore, experiments with cultured mesothelioma cells suggest the importance of MnSOD in the proliferation and apoptosis caused by drug exposure.
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Affiliation(s)
- K Kahlos
- Department of Internal Medicine, University of Oulu, Oulu, Finland.
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455
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Bär PR. Motor neuron disease in vitro: the use of cultured motor neurons to study amyotrophic lateral sclerosis. Eur J Pharmacol 2000; 405:285-95. [PMID: 11033335 DOI: 10.1016/s0014-2999(00)00560-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) is a lethal neurodegenerative disease in which motor neurons in the nervous system die. The cause is unknown, and no effective treatment exists. Mutations in the gene for superoxide dismutase found in a subpopulation have led to an animal model, but research with these mice has not produced complete insight into the disease mechanism. Studies with isolated motor neurons may produce important information. This review discusses approaches to culture motor neurons - single cells, cocultured with other cells, and in intact preparations, such as the spinal or cortical slice. Motor neurons in monoculture are suitable for acute but not for chronic studies, whereas cocultures and slices survive up to months and are used for chronic studies. Results with toxic substances believed to play a role in the disease, such as oxidants and glutamate, and of studies where the energy status of the cells is manipulated, are presented.
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Affiliation(s)
- P R Bär
- Laboratory for Experimental Neurology, Rudolf Magnus Institute for Neurosciences, University Medical Centre, Utrecht, Postbox 85500, 3508 GA, Utrecht, The Netherlands.
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456
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Abstract
The term apoptosis or programmed cell death defines a genetically encoded cell death program, which is morphologically and biochemically distinct from necrosis or accidental cell death. The characteristic morphological signs of apoptosis (cellular shrinkage, membrane blebbing, nuclear condensation and fragmentation) are the final results of a complex biochemical cascade of events which is an integral part of physiological homeostasis. Techniques designed to identify, quantitate and characterize apoptosis are numerous, but flow cytometry (FCM) remains the methodology of choice to study the apoptotic cascade in relation to cell type, trigger and time. This review outlines the main stages of the apoptotic cascade together with current FCM methods. All FCM apoptosis assays described have a solid experimental basis and have been used successfully in basic research on molecular and biochemical mechanisms of apoptosis. In various clinical settings the ability to follow the apoptotic process in patient samples may offer the rationale for optimal treatment schedules.
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Affiliation(s)
- I Vermes
- Department of Clinical Chemistry, Medical Spectrum Twente, P.O. Box 50000, 7500 KA, Enschede, The Netherlands.
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457
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Zhang J, Mikecz K, Finnegan A, Glant TT. Spontaneous thymocyte apoptosis is regulated by a mitochondrion-mediated signaling pathway. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2000; 165:2970-4. [PMID: 10975804 DOI: 10.4049/jimmunol.165.6.2970] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Most thymocytes that have not successfully rearranged their TCR genes or that express a receptor with subthreshold avidity for self-Ag/MHC enter a default apoptosis pathway, death by neglect. Spontaneous thymocyte apoptosis (STA), at least in part, may mimic this process in vitro. However, the molecular mechanism(s) by which thymocytes undergo this spontaneous apoptosis remains unknown. Here, we report that caspsase-1 and caspase-3 are activated during STA, but these caspases are dispensable for this apoptotic process. The inhibition of STA by a pan-caspase inhibitor, zVAD, suggests that multiple caspase pathways exist. Importantly, the early release of cytochrome c from mitochondria closely correlates with the degradation of Bcl-2 and Bcl-xL and a decrease in the ratios of Bcl-2 and Bcl-xL to Bax during STA. These findings suggest that the degradation of Bcl-2 and Bcl-xL may favor Bax to induce cytochrome c release from mitochondria, which subsequently activates downstream caspases in STA. Our data provide the first biochemical insight into the molecular mechanism of STA.
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Affiliation(s)
- J Zhang
- Departments of Orthopedic Surgery, Biochemistry, Medicine, and Immunology/Microbiology, Rush University at Rush-Presbyterian-St. Luke's Medical Center, Chicago, IL 60612, USA.
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458
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Gautier I, Geeraert V, Coppey J, Coppey-Moisan M, Durieux C. A moderate but not total decrease of mitochondrial membrane potential triggers apoptosis in neuron-like cells. Neuroreport 2000; 11:2953-6. [PMID: 11006972 DOI: 10.1097/00001756-200009110-00024] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The effects of various degrees of perturbation of the mitochondrial membrane potential (mt delta psi) on apoptosis was investigated by intensified fluorescence digital-imaging microscopy on neuron-like cells, ND7. Mt delta psi was either decreased by 40% by the protonophore carbonyl cyanide p-trifluoromethoxyphenylhydrazone (FCCP 100 nM, 15 min) or completely collapsed (FCCP 10 microM, 60 min). A moderate decrease of mt delta psi induced a reduction of mitochondrial NADH, followed by exposure of phosphatidyl serine and then by chromatin condensation, 36% of nuclei being condensed 60 min after FCCP treatment. During these stages, mitochondrion morphology was fully preserved. In contrast, no chromatin condensation was observed after a rapid and total dissipation of mt delta psi. These results suggest that a partial decrease of mt delta psi would allow mitochondrial functions required to trigger apoptosis to be sustained.
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Affiliation(s)
- I Gautier
- Institut Jacques Monod, UMR 7592, CNRS, Universités P6/P7, Paris, France
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459
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Hiura TS, Li N, Kaplan R, Horwitz M, Seagrave JC, Nel AE. The role of a mitochondrial pathway in the induction of apoptosis by chemicals extracted from diesel exhaust particles. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2000; 165:2703-11. [PMID: 10946301 DOI: 10.4049/jimmunol.165.5.2703] [Citation(s) in RCA: 161] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We are interested in the cytotoxic and proinflammatory effects of particulate pollutants in the respiratory tract. We demonstrate that methanol extracts made from diesel exhaust particles (DEP) induce apoptosis and reactive oxygen species (ROS) in pulmonary alveolar macrophages and RAW 264.7 cells. The toxicity of these organic extracts mimics the cytotoxicity of the intact particles and could be suppressed by the synthetic sulfhydryl compounds, N-acetylcysteine and bucillamine. Because DEP-induced apoptosis follows cytochrome c release, we studied the effect of DEP chemicals on mitochondrially regulated death mechanisms. Crude DEP extracts induced ROS production and perturbed mitochondrial function before and at the onset of apoptosis. This mitochondrial perturbation follows an orderly sequence of events, which commence with a change in mitochondrial membrane potential, followed by cytochrome c release, development of membrane asymmetry (annexin V staining), and propidium iodide uptake. Structural damage to the mitochondrial inner membrane, evidenced by a decrease in cardiolipin mass, leads to O-*2 generation and uncoupling of oxidative phosphorylation (decreased intracellular ATP levels). N-acetylcysteine reversed these mitochondrial effects and ROS production. Overexpression of the mitochondrial apoptosis regulator, Bcl-2, delayed but did not suppress apoptosis. Taken together, these results suggest that DEP chemicals induce apoptosis in macrophages via a toxic effect on mitochondria.
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Affiliation(s)
- T S Hiura
- Division of Clinical Immunology and Allergy, Department of Medicine, University of California Medical School, Los Angeles, CA 90095, USA
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460
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Oxidative stress and apoptosis. PATHOPHYSIOLOGY : THE OFFICIAL JOURNAL OF THE INTERNATIONAL SOCIETY FOR PATHOPHYSIOLOGY 2000; 7:153-163. [PMID: 10996508 DOI: 10.1016/s0928-4680(00)00053-5] [Citation(s) in RCA: 828] [Impact Index Per Article: 34.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Apoptosis or programmed cell death, is essential for the normal functioning and survival of most multi-cellular organisms. The morphological and biochemical characteristics of apoptosis, however, are highly conserved during the evolution. It is currently believed that apoptosis can be divided into at least three functionally distinct phases, i.e. induction, effector and execution phase. Recent studies have demonstrated that reactive oxygen species (ROS) and the resulting oxidative stress play a pivotal role in apoptosis. Antioxidants and thiol reductants, such as N-acetylcysteine, and overexpression of manganese superoxide (MnSOD) can block or delay apoptosis. Bcl-2, an endogenously produced protein, has been shown to prevent cells from dying of apoptosis apparently by an antioxidative mechanism. Taken together ROS, and the resulting cellular redox change, can be part of signal transduction pathway during apoptosis. It is now established that mitochondria play a prominent role in apoptosis. During mitochondrial dysfunction, several essential players of apoptosis, including pro-caspases, cytochrome C, apoptosis-inducing factor (AIF), and apoptotic protease-activating factor-1 (APAF-1) are released into the cytosol. The multimeric complex formation of cytochrome C, APAF-1 and caspase 9 activates downstream caspases leading to apoptotic cell death. All the three functional phases of apoptosis are under the influence of regulatory controls. Thus, increasing evidences provide support that oxidative stress and apoptosis are closely linked physiological phenomena and are implicated in pathophysiology of some of the chronic diseases including AIDS, autoimmunity, cancer, diabetes mellitus, Alzheimer's and Parkinson's and ischemia of heart and brain.
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461
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Ahn YH, Koh JY, Hong SH. Protein synthesis-dependent but Bcl-2-independent cytochrome C release in zinc depletion-induced neuronal apoptosis. J Neurosci Res 2000; 61:508-14. [PMID: 10956420 DOI: 10.1002/1097-4547(20000901)61:5<508::aid-jnr5>3.0.co;2-v] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Previously, we reported that chelation of intracellular zinc with N, N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN)-induced macromolecule synthesis-dependent apoptosis of cultured cortical neurons. According to the current theory of apoptosis, release of mitochondrial cytochrome C into the cytosol is required for caspase activation. In the present study, we examined whether cytochrome C release is dependent on macromolecule synthesis. Exposure of cortical cultures to 2 microM TPEN for 24 hr induced apoptosis as previously described. Fluorescence immunocytochemical staining as well as immunoblots of cell extracts revealed the release of cytochrome C into the cytosol 18-20 hr after the exposure onset. The cytochrome C release was completely blocked by the addition of cycloheximide or actinomycin D. Addition of the caspase inhibitor zVAD-fmk did not attenuate the cytochrome C release, whereas it blocked TPEN-induced apoptosis. Because Bcl-2 has been shown to block cytochrome C release potently, we exposed human neuroblastoma cells (SH-SY5Y) to TPEN. Whereas Bcl-2 overexpression completely blocked both cytochrome C release and apoptosis induced by staurosporine, it attenuated neither induced by TPEN. The present results suggest that, in neurons, macromolecule synthesis inhibitors act upstream of cytochrome C release to block apoptosis and that, in addition to the classical Bcl-2 sensitive pathway, there may exist a Bcl-2-insensitive pathway for cytochrome C release.
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Affiliation(s)
- Y H Ahn
- School of Biological Sciences and Institute for Molecular Biology and Genetics, Seoul National University, Seoul, Korea
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462
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Ding WX, Shen HM, Ong CN. Critical role of reactive oxygen species and mitochondrial permeability transition in microcystin-induced rapid apoptosis in rat hepatocytes. Hepatology 2000; 32:547-55. [PMID: 10960448 DOI: 10.1053/jhep.2000.16183] [Citation(s) in RCA: 196] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/07/2022]
Abstract
Microcystin-LR (M-LR) is a specific hepatotoxin. At present, the exact toxic mechanism of its action remains unclear though apoptosis is believed to be involved. This study was designed to investigate the role of reactive oxygen species (ROS) and mitochondrial permeability transition (MPT) in the M-LR-induced apoptotic process. Morphologic changes such as cell shrinkage, externalization of cell membrane phosphatidylserine, DNA fragmentation, and nuclear condensation suggest that M-LR causes rapid apoptosis in hepatocytes. Confocal microscopy revealed that M-LR exposure led to the onset of MPT and mitochondrial depolarization, evidenced by (1) redistribution of calcein fluorescence from cytosol to mitochondria, and (2) loss of mitochondrial tetramethyrhodamine methyl ester (TMRM) fluorescence; both occurred before apoptosis. Moreover, there was a significant and rapid increase of ROS level before the onset of MPT and loss of MMP, indicating a critical role of ROS in M-LR-induced apoptosis. Deferoxamine (DFO), an iron chelator, prevented the increase of ROS production, delayed the onset of MPT, and, subsequently, cell death. In addition, a specific MPT inhibitor, cyclosporin A (CsA), blocked the M-LR-induced ROS formation, onset of MPT, and mitochondrial depolarization as well as cell death. Thus, we conclude that the M-LR-induced ROS formation leads to the onset of MPT and apoptosis.
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Affiliation(s)
- W X Ding
- Center for Environmental and Occupational Health, Department of Community, Occupational and Family Medicine, Faculty of Medicine, National University of Singapore
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463
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Yang CF, Shen HM, Ong CN. Intracellular thiol depletion causes mitochondrial permeability transition in ebselen-induced apoptosis. Arch Biochem Biophys 2000; 380:319-30. [PMID: 10933887 DOI: 10.1006/abbi.2000.1939] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Ebselen, a selenoorganic compound, has recently been shown to display a novel property of inducing apoptosis through rapid depletion of intracellular thiols in human hepatoma cells, HepG(2). The present study was thus designed to explore the mechanism of how ebselen triggers apoptosis upon depletion of intracellular thiols. The results demonstrated that ebselen treatment triggered mitochondrial permeability transition rather rapidly as revealed by redistribution of calcein green fluorescence from cytosol into mitochondria. Ebselen treatment also caused a dose- and time-dependent loss of mitochondrial membrane potential (MMP) and release of cytochrome c. Pretreatment with N-acetylcysteine, a precursor of intracellular reduced glutathione (GSH) synthesis, significantly attenuated the ebselen-induced MMP disruption and subsequently inhibited the apoptosis. In contrast, pretreatment with buthionine sulfoximine, a specific inhibitor of intracellular GSH synthesis, significantly augmented the ebselen-induced MMP alteration, and enhanced the apoptosis. Although ebselen treatment significantly increased the intracellular superoxide radical and calcium concentrations, superoxide dismutase, and BAPTA (a calcium chelator), however, failed to prevent ebselen-induced MMP loss and apoptosis. Neither caspase-9 nor caspase-3 activation was detected in ebselen-treated cells. Z-VAD-FMK, a general caspase inhibitor, also had no effect on ebselen-induced MMP decrease and apoptosis. The overall findings thus suggest that mitochondrial permeability transition resulted from intracellular thiol depletion is a critical event in ebselen-induced apoptosis.
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Affiliation(s)
- C F Yang
- Department of Community, Occupational and Family Medicine, Faculty of Medicine, MD3, National University of Singapore, 16 Medical Drive, 117597, Singapore
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464
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Agostinis P, Assefa Z, Vantieghem A, Vandenheede JR, Merlevede W, De Witte P. Apoptotic and anti-apoptotic signaling pathways induced by photodynamic therapy with hypericin. ADVANCES IN ENZYME REGULATION 2000; 40:157-82. [PMID: 10828351 DOI: 10.1016/s0065-2571(99)00021-7] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- P Agostinis
- Division of Biochemistry, Faculty of Medicine, KU Leuven, Leuven, Belgium
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465
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Cai J, Wallace DC, Zhivotovsky B, Jones DP. Separation of cytochrome c-dependent caspase activation from thiol-disulfide redox change in cells lacking mitochondrial DNA. Free Radic Biol Med 2000; 29:334-42. [PMID: 11035262 DOI: 10.1016/s0891-5849(00)00312-9] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Release of mitochondrial cytochrome c (cyt c) is an early and common event during apoptosis. Previous studies showed that the loss of cyt c triggered superoxide production by mitochondria and contributed to the oxidation of cellular thiol-disulfide redox state. In this study, we tested whether loss of the functional electron transport chain due to depleting mitochondrial DNA (mtDNA) would affect this redox-signaling mechanism during apoptosis. Results showed that cyt c release and caspase activation in response to staurosporine treatment were preserved in cells lacking mitochondrial DNA (rho0 cells). However, unlike the case with rho+ cells, in which a dramatic oxidation of intracellular glutathione (GSH) occurred after mitochondrial cyt c release, the thiol-disulfide redox state in apoptotic rho0 cells remained largely unchanged. Thus, mitochondrial signaling of caspase activation can be separated from the bioenergetic function, and mitochondrial respiratory chain is the principal source of ROS generation in staurosporine-induced apoptosis.
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Affiliation(s)
- J Cai
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, USA
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466
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Assefa Z, Vantieghem A, Garmyn M, Declercq W, Vandenabeele P, Vandenheede JR, Bouillon R, Merlevede W, Agostinis P. p38 mitogen-activated protein kinase regulates a novel, caspase-independent pathway for the mitochondrial cytochrome c release in ultraviolet B radiation-induced apoptosis. J Biol Chem 2000; 275:21416-21. [PMID: 10748072 DOI: 10.1074/jbc.m002634200] [Citation(s) in RCA: 124] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The mechanisms of UVB-induced apoptosis and the role of p38 mitogen-activated protein kinase (MAPK) were investigated in HaCaT cells. UVB doses that induced apoptosis also produced a sustained activation of p38 MAPK and mitochondrial cytochrome c release, leading to pro-caspase-3 activation. Late into the apoptotic process, UVB also induced a caspase-mediated cleavage of Bid. Caspase inhibitors benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone and benzyloxycarbonyl-Asp-Glu-Val-Asp-fluoromethylketone substantially blocked the UVB-induced apoptosis without preventing the release of mitochondrial cytochrome c and the p38 MAPK activation. The inhibition of p38 MAPK counteracted both apoptosis and cytochrome c release as well as the DEVD-amino-4-methylcoumarin cleavage activity without affecting the processing of pro-caspase-8. These results indicate that UVB induces multiple and independent apoptotic pathways, which culminate in pro-caspase-3 activation, and that the initial cytochrome c release is independent of caspase activity. Importantly, we show that a sustained p38 MAPK activation contributes to the UVB-induced apoptosis by mediating the release of mitochondrial cytochrome c into the cytosol.
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Affiliation(s)
- Z Assefa
- Division of Biochemistry and Laboratory of Dermatology, Faculty of Medicine, Katholieke Universiteit Leuven, Herestraat 49, B-3000 Leuven, Belgium
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467
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Chen JY, Cheung NH, Fung MC, Wen JM, Leung WN, Mak NK. Subcellular localization of merocyanine 540 (MC540) and induction of apoptosis in murine myeloid leukemia cells. Photochem Photobiol 2000; 72:114-20. [PMID: 10911735 DOI: 10.1562/0031-8655(2000)072<0114:slomma>2.0.co;2] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Subcellular localization of photosensitizers is thought to play a critical role in determining the mode of cell death after photodynamic treatment (PDT) of leukemia cells. Using confocal laser scanning microscopy and fluorescent organelle probes, we examined the subcellular localization of merocyanine 540 (MC540) in the murine myeloid leukemia M1 and WEHI 3B (JCS) cells. Two patterns of localization were observed: in JCS cells, MC540 was found to localize on the plasma membrane and mitochondria; and in M1 leukemia cells, MC540 was found to localize on lysosomes. The relationship between subcellular localization of MC540 and PDT-induced apoptosis was investigated. Apoptotic cell death, as judged by the formation of apoptotic nuclei, was observed 4 h after irradiation in both leukemia cell lines. Typical ladders of apoptotic DNA fragments were also detected by DNA gel electrophoresis in PDT-treated JCS and M1 cells. At the irradiation dose of 46 kJ/m2 (LD90 for JCS and LD86 for M1 cells), the percentage of apoptotic JCS and M1 cells was 78 and 38%, respectively. This study provided substantial evidence that MC540 localized differentially in the mitochondria, and the subsequent photodamage of the organelle played an important role in PDT-mediated apoptosis in myeloid leukemia cells.
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Affiliation(s)
- J Y Chen
- Department of Biology, Hong Kong Baptist University, People's Republic of China
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468
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Manion MK, Su Z, Villain M, Blalock JE. A new type of Ca
2+
channel blocker that targets Ca
2+
sensors and prevents Ca
2+
‐mediated apoptosis. FASEB J 2000. [DOI: 10.1096/fasebj.14.10.1297] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Michael K. Manion
- University of Alabama at BirminghamDepartment of Physiology and Biophysics Birmingham Alabama 35294 USA
| | - Zhengchang Su
- University of Alabama at BirminghamDepartment of Physiology and Biophysics Birmingham Alabama 35294 USA
| | - Matteo Villain
- University of Alabama at BirminghamDepartment of Physiology and Biophysics Birmingham Alabama 35294 USA
| | - J. Edwin Blalock
- University of Alabama at BirminghamDepartment of Physiology and Biophysics Birmingham Alabama 35294 USA
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469
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Diaz G, Falchi AM, Gremo F, Isola R, Diana A. Homogeneous longitudinal profiles and synchronous fluctuations of mitochondrial transmembrane potential. FEBS Lett 2000; 475:218-24. [PMID: 10869560 DOI: 10.1016/s0014-5793(00)01683-5] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
This study reports for the first time (a) the longitudinal profile of the transmembrane potential (mDeltapsi) of single mitochondria using a Nernstian fluorescent probe and (b) the distribution of mDeltapsi fluctuations of mitochondria undergoing permanent depolarization. Our findings show that (1) mitochondria in different energetic conditions coexist in the same cell, (2) mDeltapsi is rather homogeneous along the entire length of single mitochondria, (3) mDeltapsi is not influenced by the surrounding cytoplasmic environment and (4) mDeltapsi fluctuations occur simultaneously in groups of mitochondria connected in a network. Taken together, these findings provide further evidence for a functional relationship between mitochondrial arrangement and energetic condition.
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Affiliation(s)
- G Diaz
- Department of Cytomorphology, University of Cagliari, Cittadella Universitaria, 09042, Monserrato, Italy.
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470
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Remé CE, Grimm C, Hafezi F, Wenzel A, Williams TP. Apoptosis in the Retina: The Silent Death of Vision. NEWS IN PHYSIOLOGICAL SCIENCES : AN INTERNATIONAL JOURNAL OF PHYSIOLOGY PRODUCED JOINTLY BY THE INTERNATIONAL UNION OF PHYSIOLOGICAL SCIENCES AND THE AMERICAN PHYSIOLOGICAL SOCIETY 2000; 15:120-124. [PMID: 11390893 DOI: 10.1152/physiologyonline.2000.15.3.120] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Pathogenetic mechanisms of retinal degeneration include cell loss by apoptosis. This gene-regulated mode of single-cell death occurs in a number of widespread human diseases such as neurodegeneration. The knowledge of genes and signaling in retinal apoptosis is expanding and opens up therapeutic strategies to ameliorate blinding retinal diseases.
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Affiliation(s)
- Charlotte E. Remé
- Department of Ophthalmology, University Eye Clinic, Zurich, Switzerland
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471
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Matsuyama S, Llopis J, Deveraux QL, Tsien RY, Reed JC. Changes in intramitochondrial and cytosolic pH: early events that modulate caspase activation during apoptosis. Nat Cell Biol 2000; 2:318-25. [PMID: 10854321 DOI: 10.1038/35014006] [Citation(s) in RCA: 568] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Mitochondria trigger apoptosis by releasing caspase activators, including cytochrome c (cytC). Here we show, using a pH-sensitive green fluorescent protein (GFP), that mitochondria-dependent apoptotic stimuli (such as Bax, staurosporine and ultraviolet irradiation) induce rapid, Bcl-2-inhibitable mitochondrial alkalinization and cytosol acidification, followed by cytC release, caspase activation and mitochondrial swelling and depolarization. These events are not induced by mitochondria-independent apoptotic stimuli, such as Fas. Activation of cytosolic caspases by cytC in vitro is minimal at neutral pH, but maximal at acidic pH, indicating that mitochondria-induced acidification of the cytosol may be important for caspase activation; this finding is supported by results obtained from cells using protonophores. Cytosol acidification and cytC release are suppressed by oligomycin, a FoF1-ATPase/H +-pump inhibitor, but not by caspase inhibitors. Ectopic expression of Bax in wild-type, but not FoF1/H+-pump-deficient, yeast cells similarly results in mitochondrial matrix alkalinization, cytosol acidification and cell death. These findings indicate that mitochondria-mediated alteration of intracellular pH may be an early event that regulates caspase activation in the mitochondrial pathway for apoptosis.
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Affiliation(s)
- S Matsuyama
- Programme on Apoptosis and Cell Death Regulation, The Burnham Institute, 10901 North Torrey Pines Road, La Jolla, California 92037, USA
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472
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Rutella S, Rumi C, Pierelli L, Morosetti R, Sica S, Bonanno G, Scambia G, Leone G. Granulocyte colony-stimulating factor perturbs lymphocyte mitochondrial function and inhibits cell cycle progression. Exp Hematol 2000; 28:612-25. [PMID: 10880747 DOI: 10.1016/s0301-472x(00)00164-8] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Sera from healthy subjects receiving recombinant human granulocyte colony-stimulating factor (rHuG-CSF) to mobilize CD34(+) peripheral blood progenitors (PBPC) have been recently shown to induce unresponsiveness of allogeneic lymphocytes to mitogenic challenge. In the present investigation, the effects of rHuG-CSF on the early stages of lymphocyte activation-induced apoptosis and on lymphocyte cell cycle entry were evaluated. Sera were obtained from HLA-identical donors receiving rHuG-CSF to mobilize CD34(+) PBPC for allogeneic transplantation. Normal peripheral blood mononuclear cells (PBMC) were challenged with phytohemagglutinin (PHA) in the presence of serum collected before (preG) or after rHuG-CSF administration (postG). Mitochondrial function, that is, incorporation of 3,3'-dihexyloxacarbocyanine iodide [DiOC(6)(3)] and generation of reactive oxygen species (ROS) as well as expression of c-Myc and Bcl-2 family members (Bcl-2, Bcl-X(L), Bax) were evaluated by multiparameter flow cytometry. The activation-induced fragmentation of genomic DNA was detected by highly sensitive LM-PCR assay.CD4(+)DiOC(6)(3)(low) and CD8(+)DiOC(6)(3)(low) T lymphocytes increased and reached 32% (range 27%-38%) and 20% (range 15%-23%) of circulating T cells, respectively, on day 4 of rHuG-CSF administration. Hypergeneration of ROS could be demonstrated in 65% (range 58%-82%) of CD4(+) T lymphocytes and in 0.4% (range 0.2%-0. 8%) of circulating CD8(+) T cells. rHuG-CSF determined no alteration of mitochondrial function if added to allogeneic PBMC in vitro, thus suggesting indirect effects mediated by soluble factors; on the contrary, when PBMC were challenged with PHA in the presence of postG serum, both perturbation of mitochondrial transmembrane potential (Deltapsi(m)) and hypergeneration of ROS were induced, and lymphocytes were predominantly arrested in a G(0) -like phase of the cell cycle and displayed genomic DNA fragmentation. Interestingly, the preincubation of PBMC with a blocking antibody directed against CD95 abrogated the perturbation of lymphocyte Deltapsi(m), suggesting that the CD95 signaling pathway might play a role in the induction of apoptosis after PHA stimulation in the presence of postG serum. Moreover, Bax protein was overexpressed in postG (median fluorescence intensity = 180, range 168-186) compared with preG cultures (median fluorescence intensity = 75, range 68-80; p < 0.01), while no differences in Bcl-2, Bcl-X(L), and c-Myc staining intensity were observed. Our findings demonstrate a humoral-mediated rHuG-CSF-induced dissipation of lymphocyte mitochondrial Deltapsi(m); these effects might be mediated by Bax overexpression, with imbalance between apoptosis-promoting and apoptosis-inhibiting Bcl-2 family members and with subsequent induction of mitochondrial permeability transition. Whether immune dysfunction will favorably impact on incidence and severity of acute graft vs host disease after allogeneic PBPC transplantation remains to be determined.
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Affiliation(s)
- S Rutella
- Department of Hematology, Catholic University, Rome, Italy.
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473
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Cuvillier O, Edsall L, Spiegel S. Involvement of sphingosine in mitochondria-dependent Fas-induced apoptosis of type II Jurkat T cells. J Biol Chem 2000; 275:15691-700. [PMID: 10747891 DOI: 10.1074/jbc.m000280200] [Citation(s) in RCA: 131] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Exposure to anti-Fas antibody in Jurkat cells (type II cells), which are characterized by a weak caspase-8 activation at the death-inducing signaling complex (DISC), induced a biphasic increase in ceramide levels. The early generation of ceramide preceded transient activation of acidic ceramidase and subsequent production of sphingosine, followed by cytochrome c release, activation of caspases-2, -3, -6, -7, -8, and -9, Bid cleavage, and a later sustained ceramide accumulation. The caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl ketone inhibited early increases of ceramide and sphingosine, whereas overexpression of Bcl-x(L) had no effect, and both prevented the later sustained ceramide accumulation. Exogenous sphingosine, as well as cell-permeable C(2)-ceramide, induced cytochrome c release from mitochondria in a caspase-independent fashion leading to activation of caspase-9 and executioner caspases and, surprisingly, activation of the initiator caspase-8 and processing of its substrate Bid. These effects were also completely abolished by Bcl-x(L) overexpression. Our results suggest that sphingosine might also be involved in the mitochondria-mediated pathway of Fas-induced cell death in type II cells.
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Affiliation(s)
- O Cuvillier
- Department of Biochemistry and Molecular Biology, Georgetown University Medical Center, Washington, D. C. 20007, USA
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474
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Takano R, Hisahara S, Namikawa K, Kiyama H, Okano H, Miura M. Nerve growth factor protects oligodendrocytes from tumor necrosis factor-alpha-induced injury through Akt-mediated signaling mechanisms. J Biol Chem 2000; 275:16360-5. [PMID: 10748222 DOI: 10.1074/jbc.m910419199] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Tumor necrosis factor-alpha is thought to be one of the most important inflammatory cytokines associated with the demyelinating disease multiple sclerosis. We determined whether neurotrophins could protect oligodendrocytes from tumor necrosis factor-alpha-mediated cytotoxicity. Among the neurotrophins tested, nerve growth factor was most effective at preventing cell death. Nerve growth factor also prevented the tumor necrosis factor-induced loss of mitochondrial membrane potential. Overexpression of constitutively active Akt, a downstream target of phosphatidylinositol 3-kinase, but not of constitutively active MEK, protected oligodendrocytes from tumor necrosis factor-induced injury. Moreover, overexpression of dominant-negative Akt negated the protective effects of nerve growth factor on tumor necrosis factor-mediated oligodendrocyte cytotoxicity. These findings indicate that the Akt pathway is crucial in nerve growth factor-mediated oligodendrocyte protection.
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Affiliation(s)
- R Takano
- Division of Neuroanatomy and Core Research for Evolutional Science and Technology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan
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475
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Abstract
Axonal injury is a feature of traumatic brain injury (TBI) contributing to both morbidity and mortality. The traumatic axon injury (TAI) results from focal perturbations of the axolemma, allowing for calcium influx triggering local intraaxonal cytoskeletal and mitochondrial damage. This mitochondrial damage has been posited to cause local bioenergetic failure, leading to axonal failure and disconnection; however, this mitochondrial damage may also lead to the release of cytochrome c (cyto-c), which then activates caspases with significant adverse intraaxonal consequences. In the current communication, we examine this possibility. Rats were subjected to TBI, perfused with aldehydes at 15-360 min after injury, and processed for light microscopic (LM) and electron microscopic (EM) single-labeling immunohistochemistry to detect extramitochondrially localized cytochrome c (cyto-c) and the signature protein of caspase-3 activation (120 kDa breakdown product of alpha-spectrin) in TAI. Combinations of double-labeling fluorescent immunohistochemistry (D-FIHC) were also used to demonstrate colocalization of calpain activation with cyto-c release and caspase-3-induction. In foci of TAI qualitative-quantitative LM demonstrated a parallel, significant increase in cyto-c release and caspase-3 activation over time after injury. EM analysis demonstrated that cyto-c and caspase-3 immunoreactivity were associated with mitochondrial swelling-disruption in sites of TAI. Furthermore, D-IFHC revealed a colocalization of calpain activation, cyto-c release, and caspase-3 induction in these foci, which also revealed progressive TAI. The results demonstrate that cyto-c and caspase-3 participate in the terminal processes of TAI. This suggests that those factors that play a role in the apoptosis in the neuronal soma are also major contributors to the demise of the axonal appendage.
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476
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Abstract
The paper provides an interdisciplinary evaluation of the etiology, pathogenesis, and experimental treatments of retinitis pigmentosa (RP). It addresses a 10-year controversy concerning the rate of progression of RP. One laboratory has estimated remaining visual field to be lost at a rate of 4.6% per year, whereas another laboratory estimates loss at 16-18%. This large discrepancy and lack of consensus needs resolution, since they pose serious statistical and operational problems for evaluating experimental treatment approaches to RP. The resolution of the controversy offered in the paper is based on a model of RP in which the initial rate of loss of visual field (the induction phase) is much slower than the subsequent logarithmic first-order rate of loss. The rationale for this kinetic model is that loss of mitochondrial function, possibly due to RP-genetically-related radical processes, has to reach a critical threshold value before the mitochondrial trigger of programmed cell death or apoptosis (i.e., the release of mitochondrial cytochrome c by the opening of the permeability transition pore, PTP) can be activated by an encounter with a second, but kinetically constant causative stress factor - most likely a light-stress-related factor. In its essential (two-causal) aspects, this kinetic model for RP is identical to the kinetic theories that have been proposed for the Gombertz human mortality plot. The described kinetic model for RP provides a solution to the visual field-loss controversy, since the first study was performed with a population containing a greater number of patients in the slow stage of RP than the second. Another objective of the investigation was to identify possible mechanisms of how the numerous genetic mutations in the rods of RP patients could give rise to damaging free-radical reactions capable of triggering apoptosis through their adverse effects on mitochondrial function. Another reason for focusing on radical reactions in RP was to provide a rationale for the proposed use of an extensive array of antioxidants and nutritional supplements for stemming progression of RP. In particular, the investigation focuses on saving cone-dependent central vision, i.e. on saving cells not affected by the genetic problems of the rods, but cells which can become lethally damaged by a spill-over of radicals and related harmful chemical reactions occurring in the rods.The third objective deals with the development of a rationale for a new strategy for retarding RP. This involves the use of desmethyldeprenyl, a metabolite of the anti-Parkinson's drug, deprenyl. The rationale is, in part, based on an observation that desmethyldeprenyl exerts antiapoptotic activities in a variety of neurodegenerative disorders. The protective mechanism involves the overexpression of the anti-apoptotic bcl-2 gene, leading to higher concentrations of bcl-2 proteins, which by binding to mitochondria inhibits the trigger mechanism of apoptosis - the opening of PTP and release of cytochrome C. At the same time, desmethyldeprenyl causes the underexpression of the pro-apoptotic bax gene, which via bax proteins facilitates the opening of the PTP. Both the anti-apoptotic and pro-apoptotic mechanisms appear to be mediated by the binding of desmethyldeprenyl to glyceraldehyde-3-phosphate dehydrogenase. Antiapoptotic effects can also be generated by the parent compound, deprenyl, when this is used daily in low concentrations of 1-2 mg/100 kg body weight. Under these conditions, it appears that the anti-apoptotic metabolite, desmethyldeprenyl, predominates over the pro-apoptotic metabolites of deprenyl, l -methamphetamine and l -amphetamine. Methamphetamine is not formed if desmethyldeprenyl is administered directly and thus could give desmethyldeprenyl a pharmacokinetic advantage over deprenyl. (ABSTRACT TRUNCATED)
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477
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Pastorino JG, Hoek JB. Ethanol potentiates tumor necrosis factor-alpha cytotoxicity in hepatoma cells and primary rat hepatocytes by promoting induction of the mitochondrial permeability transition. Hepatology 2000; 31:1141-52. [PMID: 10796891 DOI: 10.1053/he.2000.7013] [Citation(s) in RCA: 162] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
In the present study, tumor necrosis factor-alpha (TNF-alpha) cytotoxicity is shown to be potentiated by ethanol exposure in vitro in the human hepatoma cell line, HepG2, and in rat primary hepatocytes. Exposure of HepG2 cells and primary hepatocytes for 48 hours to concentrations of ethanol ranging between 50 and 100 mmol/L significantly increased TNF-alpha cytotoxicity compared with cells treated with TNF-alpha alone. The cell killing was associated with, and dependent on, the development of the mitochondrial permeability transition (MPT). Two inhibitors of MPT pore opening, cyclosporin A and bongkrekic acid, prevented TNF-alpha cytotoxicity in the presence of ethanol. In addition to inhibiting cell death caused by TNF-alpha, blockade of MPT pore opening prevented mitochondrial depolarization, cytochrome c redistribution from the mitochondria to the cytosol, caspase 3 activation, and oligonucleosomal DNA fragmentation. Unlike the potentiation of TNF-alpha cytotoxicity by the translational inhibitor cycloheximide, ethanol promoted TNF-alpha-induced cell killing by a mechanism that was independent of caspase-8 activity. HepG2 cells overexpressing cytochrome-P4502E1 were even more sensitized by ethanol to induction of the MPT by TNF-alpha and the resultant cytotoxicity than wild-type HepG2 cells. In addition, primary hepatocytes isolated from chronically ethanol-fed rats showed enhanced susceptibility to TNF-alpha cytotoxicity compared with their isocalorically matched controls. Again as with the HepG2 cells, inhibiting MPT pore opening prevented the cytotoxicity of TNF-alpha in the primary hepatocytes isolated from ethanol-fed animals.
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Affiliation(s)
- J G Pastorino
- Thomas Jefferson University, Department of Pathology, Anatomy, and Cell Biology, Philadelphia, PA 19107, USA.
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478
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Gross A, Pilcher K, Blachly-Dyson E, Basso E, Jockel J, Bassik MC, Korsmeyer SJ, Forte M. Biochemical and genetic analysis of the mitochondrial response of yeast to BAX and BCL-X(L). Mol Cell Biol 2000; 20:3125-36. [PMID: 10757797 PMCID: PMC85607 DOI: 10.1128/mcb.20.9.3125-3136.2000] [Citation(s) in RCA: 136] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The BCL-2 family includes both proapoptotic (e.g., BAX and BAK) and antiapoptotic (e.g., BCL-2 and BCL-X(L)) molecules. The cell death-regulating activity of BCL-2 members appears to depend on their ability to modulate mitochondrial function, which may include regulation of the mitochondrial permeability transition pore (PTP). We examined the function of BAX and BCL-X(L) using genetic and biochemical approaches in budding yeast because studies with yeast suggest that BCL-2 family members act upon highly conserved mitochondrial components. In this study we found that in wild-type yeast, BAX induced hyperpolarization of mitochondria, production of reactive oxygen species, growth arrest, and cell death; however, cytochrome c was not released detectably despite the induction of mitochondrial dysfunction. Coexpression of BCL-X(L) prevented all BAX-mediated responses. We also assessed the function of BCL-X(L) and BAX in the same strain of Saccharomyces cerevisiae with deletions of selected mitochondrial proteins that have been implicated in the function of BCL-2 family members. BAX-induced growth arrest was independent of the tested mitochondrial components, including voltage-dependent anion channel (VDAC), the catalytic beta subunit or the delta subunit of the F(0)F(1)-ATP synthase, mitochondrial cyclophilin, cytochrome c, and proteins encoded by the mitochondrial genome as revealed by [rho(0)] cells. In contrast, actual cell killing was dependent upon select mitochondrial components including the beta subunit of ATP synthase and mitochondrial genome-encoded proteins but not VDAC. The BCL-X(L) protection from either BAX-induced growth arrest or cell killing proved to be independent of mitochondrial components. Thus, BAX induces two cellular processes in yeast which can each be abrogated by BCL-X(L): cell arrest, which does not require aspects of mitochondrial biochemistry, and cell killing, which does.
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Affiliation(s)
- A Gross
- Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts 02115, USA
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479
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Abstract
Human lymphocytes flown on the Space Shuttle respond poorly to mitogen stimulation and populations of the lymphoblastoid T cell line, Jurkat, manifest growth arrest, increase in apoptosis and time- and microgravity-dependent increases in the soluble form of the cell death factor, Fas/APO-1 (sFas). The potential role of apoptosis in population dynamics of space-flown lymphocytes has not been investigated previously. We flew Jurkat cells on Space Transportation System (STS)-80 and STS-95 to determine whether apoptosis and the apparent microgravity-related release of sFas are characteristic of lymphocytes in microgravity. The effects of spaceflight and ground-based tests simulating spaceflight experimental conditions, including high cell density and low serum concentration, were assessed. Immunofluorescence microscopy showed increased cell associated Fas in flown cells. Results of STS-80 and STS-95 confirmed increase in apoptosis during spaceflight and the release of sFas as a repeatable, time-dependent and microgravity-related response. Ground-based tests showed that holding cells at 1.5 million/ml in medium containing 2% serum before launch did not increase sFas. Reports of increased Fas in cells of the elderly and the increases in spaceflown cells suggest possible similarities between aging and spaceflight effects on lymphocytes.
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Affiliation(s)
- L A Cubano
- Department of Biological Sciences and Microgravity Biotechnology Laboratory, University of Alabama in Huntsville, Wilson Hall Room 360, Huntsville, AL 35899, USA
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480
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481
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Itoh M, Chiba H, Noutomi T, Takada E, Mizuguchi J. Cleavage of Bax-alpha and Bcl-x(L) during carboplatin-mediated apoptosis in squamous cell carcinoma cell line. Oral Oncol 2000; 36:277-85. [PMID: 10793331 DOI: 10.1016/s1368-8375(00)00010-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Although carboplatin (CBDCA) has been used for the treatment of several types of tumors, the complete response rate has been limited, probably because of inherent or CBDCA-induced resistance. As a first step to overcome these problems, we tried to elucidate the mechanisms of CBDCA-mediated cytotoxicity in the squamous cell carcinoma cell line MIT7. The treatment of cells with CBDCA resulted in apoptosis in a dose-dependent manner, as assessed by the propidium iodide staining method and DNA degradation in a nucleosomal pattern. The induction of apoptosis was accompanied by the decline of mitochondrial membrane potential (Deltapsi(m) ) at 12 h following CBDCA stimulation. Variant forms of p18 Bax-alpha and p16 Bcl-x(L) were generated with the down-regulation of both Bax-alpha (p21) and Bcl-x(L) (p31) at 36 and 48 h following CBDCA stimulation, suggesting that the modulation of Bcl-2 family proteins Bax-alpha and Bcl-x(L) play some role in CBDCA-mediated apoptosis. The activation of caspase-3 and -8 occurred at 12 and 24 h following the stimulation, respectively. The pretreatment of cells with pan-caspase inhibitor Z-VAD-fmk markedly prevented CBDCA-mediated cytotoxicity/apoptosis and the modulation of Bcl-2 family proteins (generation of p18 Bax-alpha and p16 Bcl-x(L) ) with only slight prevention of decline of Deltapsi(m). Taken together, these results may suggest that activation of several caspases, including caspase-3 and -8, plays some role in CBDCA-mediated apoptosis, probably through the modification of Bcl-2 family proteins, Bax-alpha and Bcl-x(L). Moreover, caspase activation may occur downstream of membrane depolarization.
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Affiliation(s)
- M Itoh
- Department of Oral & Maxillofacial-Surgery, Tokyo Medical University Hospital, 6-7-1 Nishi-Shinjuku, Shinjuku-ku, Tokyo, Japan
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482
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Hughes J, Nangaku M, Alpers CE, Shankland SJ, Couser WG, Johnson RJ. C5b-9 membrane attack complex mediates endothelial cell apoptosis in experimental glomerulonephritis. Am J Physiol Renal Physiol 2000; 278:F747-57. [PMID: 10807586 DOI: 10.1152/ajprenal.2000.278.5.f747] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We studied the role of the C5b-9 membrane attack complex in two models of inflammatory glomerulonephritis (GN) initiated by acute glomerular endothelial injury in Piebold-viral-Glaxo (PVG) complement-sufficient rats (C+), C6-deficient rats (C6-), and rats systematically depleted of complement with cobra venom factor (CVF). GN was induced by performing a left nephrectomy and selectively perfusing the right kidney with either 1) the lectin concanavalin A (Con A) followed by complement-fixing anti-Con A (Con A GN) or 2) purified complement-fixing goat anti-rat glomerular endothelial cell (GEN) antibody [immune-mediated thrombotic microangiopathy (ITM)]. Comparable levels of GEN apoptosis were detected in C+ animals in both models. CVF administration reduced GEN apoptosis by 10- to 12-fold. GEN apoptosis was C5b-9 dependent because PVG C6- rats were protected from GEN loss. Furthermore, functional inhibition of the cell surface complement regulatory protein CD59 by renal perfusion with anti-CD59 antibody in ITM resulted in a 3.5-fold increase in GEN apoptosis. Last, in Con A GN, abrogation of GEN apoptosis preserved endothelial integrity and renal function. This study demonstrates the specific role of C5b-9 in the induction of GEN apoptosis in experimental inflammatory GN, a finding with implications for diseases associated with the presence of antiendothelial cell antibodies.
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Affiliation(s)
- J Hughes
- Division of Nephrology, Department of Medicine, University of Washington, Seattle, Washington, 98195, USA.
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483
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Hatano E, Bradham CA, Stark A, Iimuro Y, Lemasters JJ, Brenner DA. The mitochondrial permeability transition augments Fas-induced apoptosis in mouse hepatocytes. J Biol Chem 2000; 275:11814-23. [PMID: 10766806 DOI: 10.1074/jbc.275.16.11814] [Citation(s) in RCA: 121] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Tumor necrosis factor-alpha receptor 1 and Fas recruit overlapping signaling pathways. To clarify the differences between tumor necrosis factor alpha (TNFalpha) and Fas pathways in hepatocyte apoptosis, primary mouse hepatocytes were treated with TNFalpha or an agonist anti-Fas antibody after infection with an adenovirus expressing an IkappaB superrepressor (Ad5IkappaB). Treatment with TNFalpha induced apoptosis in Ad5IkappaB-infected mouse hepatocytes, as we previously reported for rat hepatocytes. Ad5IkappaB plus anti-Fas antibody or actinomycin D plus anti-Fas antibody rapidly induced apoptosis, whereas anti-Fas antibody alone produced little cytotoxicity. The proteasome inhibitor (MG-132) and a dominant-negative mutant of nuclear factor-kappaB-inducing kinase also promoted TNFalpha- and Fas-mediated apoptosis. Expression of either crmA or a dominant-negative mutant of the Fas-associated death domain protein prevented TNFalpha- and Fas-mediated apoptosis. In addition, the caspase inhibitors, DEVD-cho and IETD-fmk, inhibited TNFalpha- and Fas-mediated apoptosis. In Ad5IkappaB-infected hepatocytes, caspases-3 and -8 were activated within 2 h after treatment with anti-Fas antibody or within 6 h after TNFalpha treatment. Confocal microscopy demonstrated onset of the mitochondrial permeability transition (MPT) and mitochondrial depolarization by 2-3 h after anti-Fas antibody treatment and 8-10 h after TNFalpha treatment, followed by cytochrome c release. The combination of the MPT inhibitors, cyclosporin A, and trifluoperazine, protected Ad5IkappaB-infected hepatocytes from TNFalpha-mediated apoptosis. After anti-Fas antibody, cyclosporin A and trifluoperazine decreased cytochrome c release but did not prevent caspase-3 activation and cell-death. In conclusion, nuclear factor-kappaB activation protects mouse hepatocytes against both TNFalpha- and Fas-mediated apoptosis. TNFalpha and Fas recruit similar but nonidentical, pathways signaling apoptosis. The MPT is obligatory for TNFalpha-induced apoptosis. In Fas-mediated apoptosis, the MPT accelerates the apoptogenic events but is not obligatory for them.
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Affiliation(s)
- E Hatano
- Department of Medicine, University of North Carolina, Chapel Hill, North Carolina 27599, USA
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484
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He L, Poblenz AT, Medrano CJ, Fox DA. Lead and calcium produce rod photoreceptor cell apoptosis by opening the mitochondrial permeability transition pore. J Biol Chem 2000; 275:12175-84. [PMID: 10766853 DOI: 10.1074/jbc.275.16.12175] [Citation(s) in RCA: 151] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Calcium overload is suggested to play a fundamental role in the process of rod apoptosis in chemical-induced and inherited retinal degenerations. However, this hypothesis has not been tested directly. We developed an in vitro model utilizing isolated rat retinas to determine the mechanisms underlying Ca(2+)- and/or Pb(2+)-induced retinal degeneration. Confocal microscopy, histological, and biochemical studies established that the elevated [Ca(2+)] and/or [Pb(2+)] were localized to photoreceptors and produced rod-selective apoptosis. Ca(2+) and/or Pb(2+) induced mitochondrial depolarization, swelling, and cytochrome c release. Subsequently caspase-9 and caspase-3 were sequentially activated. Caspase-7 and caspase-8 were not activated. The effects of Ca(2+) and Pb(2+) were additive and blocked completely by the mitochondrial permeability transition pore (PTP) inhibitor cyclosporin A, whereas the calcineurin inhibitor FK506 had no effect. The caspase inhibitors carbobenzoxy-Leu-Glu-His-Asp-CH(2)F and carbobenzoxy-Asp-Glu-Val-Asp-CH(2)F, but not carbobenzoxy-Ile-Glu-Thr-Asp-CH(2)F, differentially blocked post-mitochondrial events. The levels of reduced and oxidized glutathione and pyridine nucleotides in rods were unchanged. Our results demonstrate that rod mitochondria are the target site for Ca(2+) and Pb(2+). Moreover, they suggest that Ca(2+) and Pb(2+) bind to the internal metal (Me(2+)) binding site of the PTP and subsequently open the PTP, which initiates the cytochrome c-caspase cascade of apoptosis in rods.
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Affiliation(s)
- L He
- Department of Biology and Biochemistry, University of Houston, Houston, Texas 77204-6052, USA
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485
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Schmitt E, Paquet C, Beauchemin M, Dever-Bertrand J, Bertrand R. Characterization of Bax-sigma, a cell death-inducing isoform of Bax. Biochem Biophys Res Commun 2000; 270:868-79. [PMID: 10772918 DOI: 10.1006/bbrc.2000.2537] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The Ced-9/Bcl-like family of genes codes for proteins that have antiapoptotic and proapoptotic activity. Several Bax isoproteins have been detected by 2-D gel electrophoresis, and a novel human member, designated as Bax-sigma, has been identified and cloned from human cancer promyelocytic cells. Bax-sigma contains BH-3, BH-1, and BH-2 domains, putative alpha-5 and alpha-6 helices, and the carboxy-terminal hydrophobic transmembrane domain but lacks amino acids 159 to 171 compared to Bax-alpha. mRNA expression analysis by reverse transcription-polymerase chain reaction and RNase protection assays have revealed that Bax-sigma is expressed in a variety of human cancer cell lines and normal tissues. To investigate the potential role of Bax-sigma in apoptosis, first its effects were compared to those of Bax-alpha by transient expression in human B lymphoma Namalwa cells. Both Bax-sigma and Bax-alpha promoted apoptosis, as detected by DNA fragmentation and morphological analysis by electron microscopy. The apoptosis induced by Bax-sigma and Bax-alpha was correlated with their expression, cytochrome c release, and caspase activation. In a yeast two-hybrid system, Bax-sigma interacted with several Ced-9/Bcl family members but had no affinity for the human Egl-1 homologs Bik and Bad and the Ced-4 homolog Apaf-1. In human cells, Bax-sigma function was counteracted by Bcl-xL overexpression, and co-immunoprecipitation experiments indicated that Bax-sigma was associated with Bcl-xL. Furthermore, Bax-sigma overexpression increased cell death induced by various concentrations of genotoxic agents with the most pronounced effect occurring at low camptothecin and vinblastine dose levels. Our results suggest that Bax-sigma, a novel variant of Bax, encodes a protein with a proapoptotic effect and mode of action similar to those of Bax-alpha.
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Affiliation(s)
- E Schmitt
- Research Centre of the University of Montreal Hospital Centre, Notre Dame Hospital, Montreal, Quebec, H2L 4M1, Canada
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486
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Kushnareva YE, Sokolove PM. Prooxidants open both the mitochondrial permeability transition pore and a low-conductance channel in the inner mitochondrial membrane. Arch Biochem Biophys 2000; 376:377-88. [PMID: 10775426 DOI: 10.1006/abbi.2000.1730] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Mitochondria can be induced by a variety of agents/conditions to undergo a permeability transition (MPT), which nonselectively increases the permeability of the inner membrane (i.m.) to small (<1500 Da) solutes. Prooxidants are generally considered to trigger the MPT, but some investigators suggest instead that prooxidants open a Ca(2+)-selective channel in the inner mitochondrial membrane and that the opening of this channel, when coupled with Ca(2+) cycling mediated by the Ca(2+) uniporter, leads ultimately to the observed increase in mitochondrial permeability [see, e.g., Schlegel et al. (1992) Biochem. J. 285, 65]. S. A. Novgorodov and T. I. Gudz [J. Bioenerg. Biomembr. (1996) 28, 139] propose that the i.m. contains a pore that, upon exposure to prooxidants, can open to two states, one of which conducts only H(+) and one of which is the classic MPT pore. Given the current interest in increased mitochondrial permeability as a factor in apoptotic cell death, it is important to determine whether i.m. permeability is regulated in one or multiple ways and, in the latter event, to characterize each regulatory mechanism in detail. This study examined the effects of the prooxidants diamide and t-butylhydroperoxide (t-BuOOH) on the permeability of isolated rat liver mitochondria. Under the experimental conditions used, t-BuOOH induced mitochondrial swelling only in the presence of exogenous Ca(2+) (>2 microM), whereas diamide was effective in its absence. In the absence of exogenous inorganic phosphate (P(i)), (1) both prooxidants caused a collapse of the membrane potential (DeltaPsi) that preceded the onset of mitochondrial swelling; (2) cyclosporin A eliminated the swelling induced by diamide and dramatically slowed that elicited by t-BuOOH, without altering prooxidant-induced depolarization; (3) collapse of DeltaPsi was associated with Ca(2+) efflux but not with efflux of glutathione; (4) neither Ca(2+) efflux nor DeltaPsi collapse was sensitive to ruthenium red; (5) collapse of DeltaPsi was accompanied by an increase in matrix pH; no stimulation of respiration was observed; (6) Sr(2+) was able to substitute for Ca(2+) in supporting t-BuOOH-induced i.m. depolarization, but not swelling; (7) in addition to being insensitive to CsA, the collapse of DeltaPsi was also resistant to trifluoperazine, spermine, and Mg(2+), all of which block the MPT; and (8) DeltaPsi was restored (and its collapse was inhibited) upon addition of dithiothreitol, ADP, ATP or EGTA. We suggest that these results indicate that prooxidants open two channels in the i.m.: the classic MPT and a low-conductance channel with clearly distinct properties. Opening of the low-conductance channel requires sulfhydryl group oxidation and the presence of a divalent cation; both Ca(2+) and Sr(2+) are effective. The channel permits the passage of cations, including Ca(2+), but not of protons. It is insensitive to inhibitors of the classic MPT.
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Affiliation(s)
- Y E Kushnareva
- Department of Pharmacology and Experimental Therapeutics, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA
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487
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Abstract
Liver cell death is triggered by a number of insults arising from the external environment or from within the cell. These insults may engage cell surface receptors with death domaines leading to a proteolytic cascade involving initiator and executioner caspases and an apoptotic demise. Alternatively, the insults may profoundly disrupt mitochondrial function and result in loss of homeostasis accompanied by activation of hydrolases and a necrotic or lytic demise. The distinction between apoptotic and necrotic cell death has become blurred recently by the recognition that the same stimuli can induce either form of cell death as well as caspase independent apoptosis. Mitochondria play a key role in the shape of cell death; selective release of mediators amplifies the apoptosis program and profound loss of mitochondrial function leads to necrosis. Reactive oxygen metabolites and nitric oxide participate as initiating factors and modulators. The extensive knowledge gained in recent years about the mechanisms of cell death will undoubtedly lead to new and exciting advances in the prevention and treatment of liver diseases. Important targets include death receptors, death signaling mechanisms, the mitochondrial permeability transition and approaches which selectively inhibit or activate cell death in parenchymal versus nonparenchymal cells.
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Affiliation(s)
- N Kaplowitz
- USC Research Center for Liver Diseases and the Division of Gastrointestinal and Liver Diseases, Keck School of Medicine of the University of Southern California, Los Angeles 90033, USA.
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488
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Galán A, García-Bermejo ML, Troyano A, Vilaboa NE, de Blas E, Kazanietz MG, Aller P. Stimulation of p38 mitogen-activated protein kinase is an early regulatory event for the cadmium-induced apoptosis in human promonocytic cells. J Biol Chem 2000; 275:11418-24. [PMID: 10753958 DOI: 10.1074/jbc.275.15.11418] [Citation(s) in RCA: 132] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Pulse treatment of U-937 promonocytic cells with cadmium chloride (2 h at 200 microM) provoked apoptosis and induced a rapid phosphorylation of p38 mitogen-activated protein kinase (p38(MAPK)) as well as a late phosphorylation of extracellular signal-regulated protein kinases (ERK1/2). However, although the p38(MAPK)-specific inhibitor SB203580 attenuated apoptosis, the process was not affected by the ERK-specific inhibitor PD98059. The attenuation of the cadmium-provoked apoptosis by SB203580 was a highly specific effect. In fact, the kinase inhibitor did not prevent the generation of apoptosis by heat shock and camptothecin, nor the generation of necrosis by cadmium treatment of glutathione-depleted cells, nor the cadmium-provoked activation of the stress response. The generation of apoptosis was preceded by intracellular H(2)O(2) accumulation and was accompanied by the disruption of mitochondrial transmembrane potential, both of which were inhibited by SB203580. On the other hand, the antioxidant agent butylated hydroxyanisole-inhibited apoptosis but did not prevent p38(MAPK) phosphorylation. In a similar manner, p38(MAPK) phosphorylation was not affected by the caspase inhibitors Z-VAD and DEVD-CHO, which nevertheless prevented apoptosis. These results indicate that p38(MAPK) activation is an early and specific regulatory event for the cadmium-provoked apoptosis in promonocytic cells.
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Affiliation(s)
- A Galán
- Centro de Investigaciones Biológicas, CSIC, 28006 Madrid, Spain
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489
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Roucou X, Prescott M, Devenish RJ, Nagley P. A cytochrome c-GFP fusion is not released from mitochondria into the cytoplasm upon expression of Bax in yeast cells. FEBS Lett 2000; 471:235-9. [PMID: 10767430 DOI: 10.1016/s0014-5793(00)01404-6] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
To study Bax-induced release of cytochrome c in vivo, we have expressed a cytochrome c-GFP (green fluorescent protein) fusion in Saccharomyces cerevisiae cells null for the expression of the endogenous cytochrome. We show here that cytochrome c-GFP is efficiently localised to mitochondria and able to function as an electron carrier between complexes III and IV of the respiratory chain. Strikingly, while natural cytochrome c is released into the cytoplasm upon expression of Bax, the cytochrome c-GFP fusion is not. Nevertheless, cells co-expressing Bax and the cytochrome c-GFP fusion die, indicating that mitochondrial release of cytochrome c is not essential for cell death to occur in yeast. The failure to release cytochrome c-GFP is presumed to arise from increased bulk due to the GFP moiety. We propose that in intact yeast cells, Bax-induced release of cytochrome c into the cytoplasm occurs through a selective pore and not as a consequence of the non-specific breakage of the mitochondrial outer membrane.
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Affiliation(s)
- X Roucou
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Australia
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490
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Abstract
Apoptosis research has recently experienced a change from a paradigm in which the nucleus determined the apoptotic process to a paradigm in which caspases and, more recently, mitochondria constitute the center of death control. Mitochondria undergo major changes in membrane integrity before classical signs of cell death become manifest. These changes concern both the inner and the outer mitochondrial membranes, leading to the dissipation of the inner transmembrane potential (DeltaPsi(m)) and/or the release of intermembrane proteins through the outer membrane. An ever-increasing number of endogenous, viral, or xenogeneic effectors directly act on mitochondria to trigger permeabilization. At least in some cases, this is achieved by a direct action on the permeability transition pore complex (PTPC), a multiprotein ensemble containing proteins from both mitochondrial membranes, which interact with pro- and antiapoptotic members of the Bcl-2 family. At present, it is elusive whether opening of the PTPC is the only physiological mechanism leading to mitochondrial membrane permeabilization. Proteins released from mitochondria during apoptosis include caspases (mainly caspases 2, 3, and 9), caspase activators (cytochrome c, hsp 10), as well as a caspase-independent death effector, AIF (apoptosis inducing factor). The functional hierarchy among these proteins and their actual impact on the decision between death and life is elusive.
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Affiliation(s)
- M Loeffler
- Centre National de la Recherche Scientifique, ERS1984, 19 rue Guy Môquet, Villejuif, F-94801, France
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491
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Rokhlin OW, Gudkov AV, Kwek S, Glover RA, Gewies AS, Cohen MB. p53 is involved in tumor necrosis factor-alpha-induced apoptosis in the human prostatic carcinoma cell line LNCaP. Oncogene 2000; 19:1959-68. [PMID: 10773886 DOI: 10.1038/sj.onc.1203453] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The human prostatic carcinoma cell line LNCaP is sensitive to TNF-alpha treatment and expresses wild-type p53. To analyse the possible role of p53 in TNF-alpha-mediated apoptosis, we generated a derivative of LNCaP, LN-56, expressing a dominant-negative element of p53, GSE56. P53 inactivation in LN-56 was associated with an increased resistance to apoptosis induced by TNF-alpha. Surface expression of TNF-alpha receptors was unchanged in LN-56 compared to LNCaP. TNF-alpha treatment resulted in accumulation of p53 in LNCaP and upregulation of p21/WAF1. Activation of caspase-7 and PARP proteolysis were delayed in LN-56 under TNF-alpha treatment. TNF-alpha-induced apoptosis in LNCaP cells was accompanied by caspase-dependent proteolysis of p21/WAF1 and Rb, which was significantly attenuated in LN-56. Cytochrome c release was induced by TNF-alpha treatment in both cell lines, but caspase-9 was not activated. LNCaP and LN-56 were injected s.c. in nude mice and tumors were identified in all LN-56, but not LNCaP, bearing mice indicating that p53 plays an important role in growth control of prostatic neoplasms. Interestingly, accumulation of p53 in TNF-alpha-treated LNCaP cells was decreased in the presence of the caspase inhibitor Z-VAD-FMK, suggesting a new role of activated caspases in acceleration of p53 response. In summary, these results indicate that p53 is involved in TNF-alpha-mediated apoptosis in LNCaP.
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Affiliation(s)
- O W Rokhlin
- Department of Pathology, The University of Iowa, Iowa City, Iowa, IA 52242, USA
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492
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Albensi BC, Sullivan PG, Thompson MB, Scheff SW, Mattson MP. Cyclosporin ameliorates traumatic brain-injury-induced alterations of hippocampal synaptic plasticity. Exp Neurol 2000; 162:385-9. [PMID: 10739643 DOI: 10.1006/exnr.1999.7338] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Although traumatic brain injury (TBI) often results in impaired learning and memory functions, the underlying mechanisms are unknown and there are currently no treatments that can preserve such functions. We studied plasticity at CA3-CA1 synapses in hippocampal slices from rats subjected to controlled cortical impact TBI. Long-term potentiation (LTP) of synaptic transmission was markedly impaired, whereas long-term depression (LTD) was enhanced, 48 h following TBI when compared to unoperated and sham control rats. Post-TBI administration of cyclosporin A, a compound that stabilizes mitochondrial function, resulted in a highly significant amelioration of the impairment of LTP and completely prevented the enhancement of LTD. Our data suggest that alterations in hippocampal synaptic plasticity may be responsible for learning and memory deficits resulting from TBI and that agents such as cyclosporin A that stabilize mitochondrial function may be effective treatments for TBI.
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Affiliation(s)
- B C Albensi
- Sanders-Brown Research Center on Aging and Department of Anatomy & Neurobiology, University of Kentucky, Lexington, Kentucky 40536, USA
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493
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Liu D, Martino G, Thangaraju M, Sharma M, Halwani F, Shen SH, Patel YC, Srikant CB. Caspase-8-mediated intracellular acidification precedes mitochondrial dysfunction in somatostatin-induced apoptosis. J Biol Chem 2000; 275:9244-50. [PMID: 10734062 DOI: 10.1074/jbc.275.13.9244] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Activation of initiator and effector caspases, mitochondrial changes involving a reduction in its membrane potential and release of cytochrome c (cyt c) into the cytosol, are characteristic features of apoptosis. These changes are associated with cell acidification in some models of apoptosis. The hierarchical relationship between these events has, however, not been deciphered. We have shown that somatostatin (SST), acting via the Src homology 2 bearing tyrosine phosphatase SHP-1, exerts cytotoxic action in MCF-7 cells, and triggers cell acidification and apoptosis. We investigated the temporal sequence of apoptotic events linking caspase activation, acidification, and mitochondrial dysfunction in this system and report here that (i) SHP-1-mediated caspase-8 activation is required for SST-induced decrease in pH(i). (ii) Effector caspases are induced only when there is concomitant acidification. (iii) Decrease in pH(i) is necessary to induce reduction in mitochondrial membrane potential, cyt c release and caspase-9 activation and (iv) depletion of ATP ablates SST-induced cyt c release and caspase-9 activation, but not its ability to induce effector caspases and apoptosis. These data reveal that SHP-1-/caspase-8-mediated acidification occurs at a site other than the mitochondrion and that SST-induced apoptosis is not dependent on disruption of mitochondrial function and caspase-9 activation.
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Affiliation(s)
- D Liu
- Fraser Laboratories, Department of Medicine, Montreal, Quebec H3A 1A1, Canada
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494
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Dey R, Moraes CT. Lack of oxidative phosphorylation and low mitochondrial membrane potential decrease susceptibility to apoptosis and do not modulate the protective effect of Bcl-x(L) in osteosarcoma cells. J Biol Chem 2000; 275:7087-94. [PMID: 10702275 DOI: 10.1074/jbc.275.10.7087] [Citation(s) in RCA: 161] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
We explored the role of low mitochondrial membrane potential (DeltaPsim) and the lack of oxidative phosphorylation in apoptosis by assessing the susceptibility of osteosarcoma cell lines with and without mitochondrial DNA to staurosporine-induced death. Our cells without mitochondrial DNA had low DeltaPsim and no functional oxidative phosphorylation. Contrary to our expectation, these cells were more resistant to staurosporine-induced death than were the parental cells. This reduced susceptibility was associated with decreased activation of caspase 3 but not with the mitochondrial permeability transition pore or cytochrome c release from the mitochondria. Apoptosis in both cell lines was associated with an increase in DeltaPsim. Bcl-x(L) could protect both cell types against caspase 3 activation and apoptosis by a mechanism that does not appear to be mediated by mitochondrial function or modulation of DeltaPsim. Nevertheless, we found that Bcl-x(L) expression can stimulate cell respiration in cells with mitochondrial DNA. Our results showed that the lack of functional oxidative phosphorylation and/or low mitochondrial membrane potential are associated with an antiapoptotic effect, possibly contributing to the development of some types of cancer. It also reinforces a model in which Bcl-x(L) can exert an antiapoptotic effect by stimulating oxidative phosphorylation and/or inhibiting caspase activation.
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Affiliation(s)
- R Dey
- Department of Neurology, University of Miami, School of Medicine, Miami, Florida 33136, USA
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495
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Abstract
The induction of apoptosis, or controlled cell death, by various stimuli has been shown to activate a cascade of endoproteases, called caspases, that cleave numerous cellular proteins necessary for cellular homeostasis. This review discusses this family of proteases together with a variety of mammalian and viral regulatory proteins that act to control this activation.
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Affiliation(s)
- D K Miller
- Department of Immunology and Rheumatology, Merck Research Laboratories, Rahway, New Jersey 07065, USA.
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496
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Jacotot E, Costantini P, Laboureau E, Zamzami N, Susin SA, Kroemer G. Mitochondrial membrane permeabilization during the apoptotic process. Ann N Y Acad Sci 2000; 887:18-30. [PMID: 10668461 DOI: 10.1111/j.1749-6632.1999.tb07919.x] [Citation(s) in RCA: 109] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Apoptosis may be viewed as a triphasic process. During the pre-mitochondrial initiation phase, very different pro-apoptotic signal transduction or damage pathways can be activated. These pathways then converge on the mitochondrion, where they cause the permeabilization of the inner and/or outer membranes with consequent release of soluble intermembrane proteins into the cytosol. The process of mitochondrial membrane permeabilization would constitute the decision/effector phase of the apoptotic process. During the post-mitochondrial degradation phase downstream caspases and nucleases are activated and the cell acquires an apoptotic morphology. Recently, a number of different second messengers (calcium, ceramide derivatives, nitric oxide, reactive oxygen species) and pro-apoptotic proteins (Bax, Bak, Bid, and caspases) have been found to directly compromise the barrier function of mitochondrial membranes, when added to isolated mitochondria. The effects of several among these agents are mediated at least in part via the permeability transition pore complex (PTPC), a composite channel in which members of the Bcl-2 family interact with sessile transmembrane proteins such as the adenine nucleotide translocator. These findings suggest that the PTPC may constitute a pharmacological target for chemotherapy and cytoprotection.
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Affiliation(s)
- E Jacotot
- Centre National de la Recherche Scientifique, Unité Propre de Recherche 420, Villejuif, France
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497
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Lizard G, Miguet C, Besséde G, Monier S, Gueldry S, Neel D, Gambert P. Impairment with various antioxidants of the loss of mitochondrial transmembrane potential and of the cytosolic release of cytochrome c occuring during 7-ketocholesterol-induced apoptosis. Free Radic Biol Med 2000; 28:743-53. [PMID: 10754270 DOI: 10.1016/s0891-5849(00)00163-5] [Citation(s) in RCA: 102] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Previous investigations of our laboratory have shown that 7-ketocholesterol was a potent inducer of apoptosis involving a release of cytochrome c into the cytosol, and a lipid peroxidation process that could be the consequence of a production of radical oxygen species. According to these considerations, we asked whether some antioxidants were able to counteract 7-ketocholesterol-induced apoptosis, and whether prevention of cell death was associated with the impairment of mitochondrial events implied in the commitment to apoptosis, i.e., opening of the mitochondrial megachannels leading to the loss of the mitochondrial transmembrane potential (DeltaPsim), and release of cytochrome c from mitochondria into the cytosol. To this end, we studied the effects of glutathione (15 mM), N-acetylcysteine (15 mM), vitamin E (100 microM), vitamin C (50 microM) and melatonin (1 mM) on U937 cells treated with 7-ketocholesterol (40 microg/ml). Only glutathione, N-acetylcysteine, and vitamin E prevented apoptosis measured by the occurrence of cells with condensed and/or fragmented nuclei, as well as the loss of DeltaPsim, and the release of cytochrome c. However, all the antioxidants used were potent inhibitors of the production of O(2)(*) occuring under treatment with 7-ketocholesterol. Collectively, our data demonstrate that impairment of apoptosis by glutathione, N-acetylcysteine, and vitamin E correlates with the prevention of mitochondrial dysfunctions, and they underline that the ability of antioxidants to counteract 7-ketocholesterol-induced apoptosis does not only depend on their capability to inhibit the production of O(2)(*).
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Affiliation(s)
- G Lizard
- Inserm-U498 (Métabolisme des lipoprotéines humaines et interactions vasculaires), CHU/Hôpital du Bocage, BP 1542, 21034, Dijon Cedex, France.
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498
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Abstract
In addition to the 3 billion base pair nuclear genome, each human cell contains thousands of copies of a small, 16.5 kb circular molecule of double stranded DNA: mitochondria have their own DNA (mtDNA) which generally accounts for only 1% of the total cellular nucleic acid content. Therefore why should anyone, particularly in the field of dermatology, have an interest in this cytoplasmic organelle and its DNA? This review will address this question; there are three principle reasons: (i) mitochondria have a crucial role both in energy production and the viability of the cell and recently mitochondria have been implicated in programmed cell death (apoptosis). Although much smaller than the nuclear genome, mtDNA is equally important. MtDNA defects and the resulting mitochondrial dysfunction is an important contributor to human degenerative diseases, ageing and cancer; (ii) mtDNA is a significant target of ultraviolet radiation and current work shows that it may be useful as a candidate biomarker of cumulative exposure in skin; and (iii) there is a broad spectrum of skin manifestations that are signs of mitochondrial disorders; in addition, the frequency of skin findings in these syndromes is probably under-reported.
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Affiliation(s)
- M A Birch-Machin
- Department of Dermatology, University of Newcastle-upon-Tyne, UK.
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499
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Abstract
Exposure of cells to ionizing radiation results in complex cellular responses resulting in cell death and altered proliferation states. The underlying cytotoxic, cytoprotective and cellular stress responses to radiation are mediated by existing signaling pathways, activation of which may be amplified by intrinsic cellular radical production systems. These signaling responses include the activation of plasma membrane receptors, the stimulation of cytoplasmic protein kinases, transcriptional activation, and altered cell cycle regulation. From the data presented, there is increasing evidence for the functional links between cellular signal transduction responses and DNA damage recognition and repair, cell survival, or cell death through apoptosis or reproductive mechanisms.
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Affiliation(s)
- R K Schmidt-Ullrich
- Department of Radiation Oncology Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, Virginia 23298, USA
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500
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Kannan K, Holcombe RF, Jain SK, Alvarez-Hernandez X, Chervenak R, Wolf RE, Glass J. Evidence for the induction of apoptosis by endosulfan in a human T-cell leukemic line. Mol Cell Biochem 2000; 205:53-66. [PMID: 10821422 DOI: 10.1023/a:1007080910396] [Citation(s) in RCA: 94] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Several organochlorinated pesticides including DDT, PCBs and dieldrin have been reported to cause immune suppression and increase susceptibility to infection in animals. Often this manifestation is accompanied by atrophy of major lymphoid organs. It has been suggested that increased apoptotic cell death leading to altered T-B cell ratios, and loss of regulatory cells in critical numbers leads to perturbations in immune function. The major objective of our study was to define the mechanism by which endosulfan, an organochlorinated pesticide, induces human T-cell death using Jurkat, a human T-cell leukemic cell line, as an in vitro model. We exposed Jurkat cells to varying concentrations of endosulfan for 0-48 h and analyzed biochemical and molecular features characteristic of T-cell apoptosis. Endosulfan lowered cell viability and inhibited cell growth in a dose- and time-dependent manner. DAPI staining was used to enumerate apoptotic cells and we observed that endosulfan at 10-200 microM induced a significant percentage of cells to undergo apoptotic cell death. At 48 h, more than 90% cells were apoptotic with 50 microM of endosulfan. We confirmed these observations using both DNA fragmentation and annexin-V binding assays. It is now widely being accepted that mitochondria undergo major changes early during the apoptotic process. We examined mitochondrial transmembrane potential (deltapsim) in endosulfan treated cells to understand the role of the mitochondria in T-cell apoptosis. Within 30 min of chemical exposure, a significant percentage of cells exhibited a decreased incorporation of DiOC6(3), a cationic lipophilic dye into mitochondria indicating the disruption of deltapsim. This drop in deltapsim was both dose- and time-dependent and correlated well with other parameters of apoptosis. We also examined whether this occurred by the down regulation of bcl-2 protein expression that is likely to increase the susceptibility of Jurkat cells to endosulfan toxicity. Paradoxically, the intracellular expression of bcl-2 protein was elevated in a dose dependent manner suggesting endosulfan-induced apoptosis occurred by a non-bcl-2 pathway. Based on these data, as well as those reported elsewhere, we propose the following sequence of events to account for T-cell apoptosis induced by endosulfan: uncoupling of oxidative phosphorylation --> excess ROS production --> GSH depletion --> oxidative stress --> disruption of deltapsim --> release of cytochrome C and other apoptosis related proteins to cytosol --> apoptosis. This study reports for the first time that endosulfan can induce apoptosis in a human T-cell leukemic cell line which may have direct relevance to loss of T cells and thymocytes in vivo. Furthermore, our data strongly support a role of mitochondrial dysfunction and oxidative stress in endosulfan toxicity.
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Affiliation(s)
- K Kannan
- Feist-Weiller Cancer Center, Arthritis Center, LSU Health Sciences Center, Shreveport, LA 71130, USA
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