Science.gov

Sample records for mitochondrial death decision

  1. A role for mitochondrial aquaporins in cellular life-and-death decisions?

    PubMed

    Lee, Wing-Kee; Thévenod, Frank

    2006-08-01

    Mitochondria dominate the process of life-and-death decisions of the cell. Continuous generation of ATP is essential for cell sustenance, but, on the other hand, mitochondria play a central role in the orchestra of events that lead to apoptotic cell death. Changes of mitochondrial volume contribute to the modulation of physiological mitochondrial function, and several ion permeability pathways located in the inner mitochondrial membrane have been implicated in the mediation of physiological swelling-contraction reactions, such as the K+ cycle. However, the channels and transporters involved in these processes have not yet been identified. Osmotic swelling is also one of the fundamental characteristics exhibited by mitochondria in pathological situations, which activates downstream cascades, culminating in apoptosis. The permeability transition pore has long been postulated to be the primary mediator for water movement in mitochondrial swelling during cell death, but its molecular identity remains obscure. Inevitably, accumulating evidence shows that mitochondrial swelling induced by apoptotic stimuli can also occur independently of permeability transition pore activation. Recently, a novel mechanism for osmotic swelling of mitochondria has been described. Aquaporin-8 and -9 channels have been identified in the inner mitochondrial membrane of various tissues, including the kidney, liver, and brain, where they may mediate water transport associated with physiological volume changes, contribute to the transport of metabolic substrates, and/or participate in osmotic swelling induced by apoptotic stimuli. Hence, the recent discovery that aquaporins are expressed in mitochondria opens up new areas of investigation in health and disease.

  2. Mitochondrial fusion is regulated by Reaper to modulate Drosophila programmed cell death

    PubMed Central

    Thomenius, M; Freel, C D; Horn, S; Krieser, R; Abdelwahid, E; Cannon, R; Balasundaram, S; White, K; Kornbluth, S

    2011-01-01

    In most multicellular organisms, the decision to undergo programmed cell death in response to cellular damage or developmental cues is typically transmitted through mitochondria. It has been suggested that an exception is the apoptotic pathway of Drosophila melanogaster, in which the role of mitochondria remains unclear. Although IAP antagonists in Drosophila such as Reaper, Hid and Grim may induce cell death without mitochondrial membrane permeabilization, it is surprising that all three localize to mitochondria. Moreover, induction of Reaper and Hid appears to result in mitochondrial fragmentation during Drosophila cell death. Most importantly, disruption of mitochondrial fission can inhibit Reaper and Hid-induced cell death, suggesting that alterations in mitochondrial dynamics can modulate cell death in fly cells. We report here that Drosophila Reaper can induce mitochondrial fragmentation by binding to and inhibiting the pro-fusion protein MFN2 and its Drosophila counterpart dMFN/Marf. Our in vitro and in vivo analyses reveal that dMFN overexpression can inhibit cell death induced by Reaper or γ-irradiation. In addition, knockdown of dMFN causes a striking loss of adult wing tissue and significant apoptosis in the developing wing discs. Our findings are consistent with a growing body of work describing a role for mitochondrial fission and fusion machinery in the decision of cells to die. PMID:21475305

  3. Calcium and mitochondrial metabolism in ceramide-induced cardiomyocyte death.

    PubMed

    Parra, Valentina; Moraga, Francisco; Kuzmicic, Jovan; López-Crisosto, Camila; Troncoso, Rodrigo; Torrealba, Natalia; Criollo, Alfredo; Díaz-Elizondo, Jessica; Rothermel, Beverly A; Quest, Andrew F G; Lavandero, Sergio

    2013-08-01

    Ceramides are important intermediates in the biosynthesis and degradation of sphingolipids that regulate numerous cellular processes, including cell cycle progression, cell growth, differentiation and death. In cardiomyocytes, ceramides induce apoptosis by decreasing mitochondrial membrane potential and promoting cytochrome-c release. Ca(2+) overload is a common feature of all types of cell death. The aim of this study was to determine the effect of ceramides on cytoplasmic Ca(2+) levels, mitochondrial function and cardiomyocyte death. Our data show that C2-ceramide induces apoptosis and necrosis in cultured cardiomyocytes by a mechanism involving increased Ca(2+) influx, mitochondrial network fragmentation and loss of the mitochondrial Ca(2+) buffer capacity. These biochemical events increase cytosolic Ca(2+) levels and trigger cardiomyocyte death via the activation of calpains.

  4. Calcium and mitochondrial metabolism in ceramide-induced cardiomyocyte death

    PubMed Central

    Parra, Valentina; Moraga, Francisco; Kuzmicic, Jovan; López-Crisosto, Camila; Troncoso, Rodrigo; Torrealba, Natalia; Criollo, Alfredo; Díaz-Elizondo, Jessica; Rothermel, Beverly A.; Quest, Andrew F.G.; Lavandero, Sergio

    2014-01-01

    Ceramides are important intermediates in the biosynthesis and degradation of sphingolipids that regulatenumerous cellular processes, including cell cycle progression, cell growth, differentiation and death. In cardiomyocytes, ceramides induce apoptosis by decreasing mitochondrial membrane potential and promoting cytochrome-c release. Ca2+ overload is a common feature of all types of cell death. The aim of this study was to determine the effect of ceramides on cytoplasmic Ca2+ levels, mitochondrial function and cardiomyocyte death. Our data show that C2-ceramide induces apoptosis and necrosis in cultured cardiomyocytes by a mechanism involving increased Ca2+ influx, mitochondrial network fragmentation and loss of the mitochondrial Ca2+ buffer capacity. These biochemical events increase cytosolic Ca2+ levels and trigger cardiomyocyte death via the activation of calpains. PMID:23602992

  5. Calcium and mitochondrial metabolism in ceramide-induced cardiomyocyte death.

    PubMed

    Parra, Valentina; Moraga, Francisco; Kuzmicic, Jovan; López-Crisosto, Camila; Troncoso, Rodrigo; Torrealba, Natalia; Criollo, Alfredo; Díaz-Elizondo, Jessica; Rothermel, Beverly A; Quest, Andrew F G; Lavandero, Sergio

    2013-08-01

    Ceramides are important intermediates in the biosynthesis and degradation of sphingolipids that regulate numerous cellular processes, including cell cycle progression, cell growth, differentiation and death. In cardiomyocytes, ceramides induce apoptosis by decreasing mitochondrial membrane potential and promoting cytochrome-c release. Ca(2+) overload is a common feature of all types of cell death. The aim of this study was to determine the effect of ceramides on cytoplasmic Ca(2+) levels, mitochondrial function and cardiomyocyte death. Our data show that C2-ceramide induces apoptosis and necrosis in cultured cardiomyocytes by a mechanism involving increased Ca(2+) influx, mitochondrial network fragmentation and loss of the mitochondrial Ca(2+) buffer capacity. These biochemical events increase cytosolic Ca(2+) levels and trigger cardiomyocyte death via the activation of calpains. PMID:23602992

  6. The mitochondrial death pathway: a promising therapeutic target in diseases

    PubMed Central

    Gupta, Sanjeev; Kass, George EN; Szegezdi, Eva; Joseph, Bertrand

    2009-01-01

    The mitochondrial pathway to apoptosis is a major pathway of physiological cell death in vertebrates. The mitochondrial cell death pathway commences when apoptogenic molecules present between the outer and inner mitochondrial membranes are released into the cytosol by mitochondrial outer membrane permeabilization (MOMP). BCL-2 family members are the sentinels of MOMP in the mitochondrial apoptotic pathway; the pro-apoptotic B cell lymphoma (BCL)-2 proteins, BCL-2 associated x protein and BCL-2 antagonist killer 1 induce MOMP whereas the anti-apoptotic BCL-2 proteins, BCL-2, BCL-xl and myeloid cell leukaemia 1 prevent MOMP from occurring. The release of pro-apoptotic factors such as cytochrome c from mitochondria leads to formation of a multimeric complex known as the apoptosome and initiates caspase activation cascades. These pathways are important for normal cellular homeostasis and play key roles in the pathogenesis of many diseases. In this review, we will provide a brief overview of the mitochondrial death pathway and focus on a selection of diseases whose pathogenesis involves the mitochondrial death pathway and we will examine the various pharmacological approaches that target this pathway. PMID:19220575

  7. Mitochondrial and Cell Death Mechanisms in Neurodegenerative Diseases

    PubMed Central

    Martin, Lee J.

    2010-01-01

    Alzheimer’s disease (AD), Parkinson’s disease (PD) and amyotrophic lateral sclerosis (ALS) are the most common human adult-onset neurodegenerative diseases. They are characterized by prominent age-related neurodegeneration in selectively vulnerable neural systems. Some forms of AD, PD, and ALS are inherited, and genes causing these diseases have been identified. Nevertheless, the mechanisms of the neuronal cell death are unresolved. Morphological, biochemical, genetic, as well as cell and animal model studies reveal that mitochondria could have roles in this neurodegeneration. The functions and properties of mitochondria might render subsets of selectively vulnerable neurons intrinsically susceptible to cellular aging and stress and overlying genetic variations, triggering neurodegeneration according to a cell death matrix theory. In AD, alterations in enzymes involved in oxidative phosphorylation, oxidative damage, and mitochondrial binding of Aβ and amyloid precursor protein have been reported. In PD, mutations in putative mitochondrial proteins have been identified and mitochondrial DNA mutations have been found in neurons in the substantia nigra. In ALS, changes occur in mitochondrial respiratory chain enzymes and mitochondrial cell death proteins. Transgenic mouse models of human neurodegenerative disease are beginning to reveal possible principles governing the biology of selective neuronal vulnerability that implicate mitochondria and the mitochondrial permeability transition pore. This review summarizes how mitochondrial pathobiology might contribute to neuronal death in AD, PD, and ALS and could serve as a target for drug therapy. PMID:21258649

  8. Increased Mitochondrial Activity in Anthrax-Induced Cell Death

    PubMed Central

    Li, Chi

    2009-01-01

    Pathogenesis of anthrax lethal toxin (LT) is attributed to its ability to cause death of infected cells. New work has demonstrated that increase of mitochondrial F1F0 ATPase activity and subsequent depletion of cellular ATP level are critical early events during LT-induced cell death. PMID:26124679

  9. Mitochondrial dynamics and cell death in heart failure.

    PubMed

    Marín-García, José; Akhmedov, Alexander T

    2016-03-01

    The highly regulated processes of mitochondrial fusion (joining), fission (division) and trafficking, collectively called mitochondrial dynamics, determine cell-type specific morphology, intracellular distribution and activity of these critical organelles. Mitochondria are critical for cardiac function, while their structural and functional abnormalities contribute to several common cardiovascular diseases, including heart failure (HF). The tightly balanced mitochondrial fusion and fission determine number, morphology and activity of these multifunctional organelles. Although the intracellular architecture of mature cardiomyocytes greatly restricts mitochondrial dynamics, this process occurs in the adult human heart. Fusion and fission modulate multiple mitochondrial functions, ranging from energy and reactive oxygen species production to Ca(2+) homeostasis and cell death, allowing the heart to respond properly to body demands. Tightly controlled balance between fusion and fission is of utmost importance in the high energy-demanding cardiomyocytes. A shift toward fission leads to mitochondrial fragmentation, while a shift toward fusion results in the formation of enlarged mitochondria and in the fusion of damaged mitochondria with healthy organelles. Mfn1, Mfn2 and OPA1 constitute the core machinery promoting mitochondrial fusion, whereas Drp1, Fis1, Mff and MiD49/51 are the core components of fission machinery. Growing evidence suggests that fusion/fission factors in adult cardiomyocytes play essential noncanonical roles in cardiac development, Ca(2+) signaling, mitochondrial quality control and cell death. Impairment of this complex circuit causes cardiomyocyte dysfunction and death contributing to heart injury culminating in HF. Pharmacological targeting of components of this intricate network may be a novel therapeutic modality for HF treatment. PMID:26872674

  10. Methylglyoxal induces mitochondrial dysfunction and cell death in liver.

    PubMed

    Seo, Kyuhwa; Ki, Sung Hwan; Shin, Sang Mi

    2014-09-01

    Degradation of glucose is aberrantly increased in hyperglycemia, which causes various harmful effects on the liver. Methylglyoxal is produced during glucose degradation and the levels of methylglyoxal are increased in diabetes patients. In this study we investigated whether methylglyoxal induces mitochondrial impairment and apoptosis in HepG2 cells and induces liver toxicity in vivo. Methylglyoxal caused apoptotic cell death in HepG2 cells. Moreover, methylglyoxal significantly promoted the production of reactive oxygen species (ROS) and depleted glutathione (GSH) content. Pretreatment with antioxidants caused a marked decrease in methylglyoxal-induced apoptosis, indicating that oxidant species are involved in the apoptotic process. Methylglyoxal treatment induced mitochondrial permeability transition, which represents mitochondrial impairment. However, pretreatment with cyclosporin A, an inhibitor of the formation of the permeability transition pore, partially inhibited methylglyoxal-induced cell death. Furthermore, acute treatment of mice with methylglyoxal increased the plasma levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST), indicating liver toxicity. Collectively, our results showed that methylglyoxal increases cell death and induces liver toxicity, which results from ROS-mediated mitochondrial dysfunction and oxidative stress. PMID:25343013

  11. Death Penalty Decisions: Instruction Comprehension, Attitudes, and Decision Mediators.

    PubMed

    Patry, Marc W; Penrod, Steven D

    2013-01-01

    A primary goal of this research was to empirically evaluate a set of assumptions, advanced in the Supreme Court's ruling in Buchanan v. Angelone (1998), about jury comprehension of death penalty instructions. Further, this research examined the use of evidence in capital punishment decision making by exploring underlying mediating factors upon which death penalty decisions may be based. Manipulated variables included the type of instructions and several variations of evidence. Study 1 was a paper and pencil study of 245 undergraduate mock jurors. The experimental design was an incomplete 4×2×2×2×2 factorial model resulting in 56 possible conditions. Manipulations included four different types of instructions, presence of a list of case-specific mitigators to accompany the instructions, and three variations in the case facts: age of the defendant, bad prior record, and defendant history of emotional abuse. Study 2 was a fully-crossed 2×2×2×2×2 experiment with four deliberating mock juries per cell. Manipulations included jury instructions (original or revised), presence of a list of case-specific mitigators, defendant history of emotional abuse, bad prior record, and heinousness of the crime. The sample of 735 jury-eligible participants included 130 individuals who identified themselves as students. Participants watched one of 32 stimulus videotapes based on a replication of a capital sentencing hearing. The present findings support previous research showing low comprehension of capital penalty instructions. Further, we found that higher instruction comprehension was associated with higher likelihood of issuing life sentence decisions. The importance of instruction comprehension is emphasized in a social cognitive model of jury decision making at the sentencing phase of capital cases.

  12. Death Penalty Decisions: Instruction Comprehension, Attitudes, and Decision Mediators

    PubMed Central

    Patry, Marc W.; Penrod, Steven D.

    2013-01-01

    A primary goal of this research was to empirically evaluate a set of assumptions, advanced in the Supreme Court’s ruling in Buchanan v. Angelone (1998), about jury comprehension of death penalty instructions. Further, this research examined the use of evidence in capital punishment decision making by exploring underlying mediating factors upon which death penalty decisions may be based. Manipulated variables included the type of instructions and several variations of evidence. Study 1 was a paper and pencil study of 245 undergraduate mock jurors. The experimental design was an incomplete 4×2×2×2×2 factorial model resulting in 56 possible conditions. Manipulations included four different types of instructions, presence of a list of case-specific mitigators to accompany the instructions, and three variations in the case facts: age of the defendant, bad prior record, and defendant history of emotional abuse. Study 2 was a fully-crossed 2×2×2×2×2 experiment with four deliberating mock juries per cell. Manipulations included jury instructions (original or revised), presence of a list of case-specific mitigators, defendant history of emotional abuse, bad prior record, and heinousness of the crime. The sample of 735 jury-eligible participants included 130 individuals who identified themselves as students. Participants watched one of 32 stimulus videotapes based on a replication of a capital sentencing hearing. The present findings support previous research showing low comprehension of capital penalty instructions. Further, we found that higher instruction comprehension was associated with higher likelihood of issuing life sentence decisions. The importance of instruction comprehension is emphasized in a social cognitive model of jury decision making at the sentencing phase of capital cases. PMID:24072981

  13. Death Penalty Decisions: Instruction Comprehension, Attitudes, and Decision Mediators.

    PubMed

    Patry, Marc W; Penrod, Steven D

    2013-01-01

    A primary goal of this research was to empirically evaluate a set of assumptions, advanced in the Supreme Court's ruling in Buchanan v. Angelone (1998), about jury comprehension of death penalty instructions. Further, this research examined the use of evidence in capital punishment decision making by exploring underlying mediating factors upon which death penalty decisions may be based. Manipulated variables included the type of instructions and several variations of evidence. Study 1 was a paper and pencil study of 245 undergraduate mock jurors. The experimental design was an incomplete 4×2×2×2×2 factorial model resulting in 56 possible conditions. Manipulations included four different types of instructions, presence of a list of case-specific mitigators to accompany the instructions, and three variations in the case facts: age of the defendant, bad prior record, and defendant history of emotional abuse. Study 2 was a fully-crossed 2×2×2×2×2 experiment with four deliberating mock juries per cell. Manipulations included jury instructions (original or revised), presence of a list of case-specific mitigators, defendant history of emotional abuse, bad prior record, and heinousness of the crime. The sample of 735 jury-eligible participants included 130 individuals who identified themselves as students. Participants watched one of 32 stimulus videotapes based on a replication of a capital sentencing hearing. The present findings support previous research showing low comprehension of capital penalty instructions. Further, we found that higher instruction comprehension was associated with higher likelihood of issuing life sentence decisions. The importance of instruction comprehension is emphasized in a social cognitive model of jury decision making at the sentencing phase of capital cases. PMID:24072981

  14. New Insights into Mitochondrial Structure during Cell Death

    PubMed Central

    Perkins, Guy; Bossy-Wetzel, Ella; Ellisman, Mark H.

    2009-01-01

    Mitochondria play a pivotal role in the cascade of events associated with cell death pathways that are involved with several forms of neurodegeneration. Recent findings show that in the Bax/Bak-dependent pathway of apoptosis, the release of cytochrome c from mitochondria is a consequence of two carefully coordinated events: opening of crista junctions triggered by OPA1 oligomer disassembly and formation of outer-membrane pores. Both steps are necessary for the complete release of proapoptotic proteins. The remodeling of mitochondrial structure accompanies this pathway, including mitochondrial fission, and cristae and crista junction alterations. Yet, there is controversy surrounding the timing of certain remodeling events and whether they are necessary early events required for the release of pro-apoptotic factors or are simply a downstream after-effect. Here, we analyze the current knowledge of mitochondrial remodeling during cell death and discuss what structural alterations occur to this organelle during neurodegeneration, focusing on the higher resolution structural correlates obtained by electron microscopy and electron tomography. PMID:19464290

  15. Role of mitochondrial function in cell death and body metabolism.

    PubMed

    Lee, Myung-Shik

    2016-01-01

    Mitochondria are the key players in apoptosis and necrosis. Mitochondrial DNA (mtDNA)-depleted r0 cells were resistant to diverse apoptosis inducers such as TNF-alpha, TNFSF10, staurosporine and p53. Apoptosis resistance was accompanied by the absence of mitochondrial potential loss or cytochrome c translocation. r0 cells were also resistant to necrosis induced by reactive oxygen species (ROS) donors due to upregulation of antioxidant enzymes such as manganese superoxide dismutase. Mitochondria also has a close relationship with autophagy that plays a critical role in the turnover of senescent organelles or dysfunctional proteins and may be included in 'cell death' category. It was demonstrated that autophagy deficiency in insulin target tissues such as skeletal muscle induces mitochondrial stress response, which leads to the induction of FGF21 as a 'mitokine' and affects the whole body metabolism. These results show that mitochondria are not simply the power plants of cells generating ATP, but are closely related to several types of cell death and autophagy. Mitochondria affect various pathophysiological events related to diverse disorders such as cancer, metabolic disorders and aging. PMID:27100503

  16. Lysosomal photodamage induces cell death via mitochondrial apoptotic pathway

    NASA Astrophysics Data System (ADS)

    Liu, Lei; Wang, Xian-wang; Li, Hui

    2009-11-01

    Lysosomal photosensitizers have been used in photodynamic therapy (PDT). Combination of such photosensitizers and light causes lysosomal photodamage, inducing cell death. The lysosomal disruption can lead to apoptosis but its signaling pathways remain to be elucidated. In this study, we selected N-aspartyl chlorin e6 (NPe6), an effective photosensitizer which preferentially accumulates in lysosomes, to study the mechanism of apoptosis caused by lysosomal photodamage. Apoptosis in living human lung adenocarcinoma cells treated by NPe6-PDT was studied using real-time single-cell analysis. In this study, the fluorescence probes Cyto c-GFP and DsRed-Mit were used to detect the spatial and temporal changes of cytochrome c in real-time in sub-cell level; the Rhodamine 123 dyes were used to monitor the changes of mitochondrial membrane potential. The results showed that, after PDT treatment,the mitochondrial membrane potential decreased, and cytochrome c released from mitochondria; The caspase-3 was activated obviously. These results suggested that lysosomal photodamage activates mitochondrial apoptotic pathway to induce cell death.

  17. Imeglimin prevents human endothelial cell death by inhibiting mitochondrial permeability transition without inhibiting mitochondrial respiration.

    PubMed

    Detaille, D; Vial, G; Borel, A-L; Cottet-Rouselle, C; Hallakou-Bozec, S; Bolze, S; Fouqueray, P; Fontaine, E

    2016-01-01

    Imeglimin is the first in a new class of oral glucose-lowering agents, having recently completed its phase 2b trial. As Imeglimin did show a full prevention of β-cell apoptosis, and since angiopathy represents a major complication of diabetes, we studied Imeglimin protective effects on hyperglycemia-induced death of human endothelial cells (HMEC-1). These cells were incubated in several oxidative stress environments (exposure to high glucose and oxidizing agent tert-butylhydroperoxide) which led to mitochondrial permeability transition pore (PTP) opening, cytochrome c release and cell death. These events were fully prevented by Imeglimin treatment. This protective effect on cell death occurred without any effect on oxygen consumption rate, on lactate production and on cytosolic redox or phosphate potentials. Imeglimin also dramatically decreased reactive oxygen species production, inhibiting specifically reverse electron transfer through complex I. We conclude that Imeglimin prevents hyperglycemia-induced cell death in HMEC-1 through inhibition of PTP opening without inhibiting mitochondrial respiration nor affecting cellular energy status. Considering the high prevalence of macrovascular and microvascular complications in type 2 diabetic subjects, these results together suggest a potential benefit of Imeglimin in diabetic angiopathy. PMID:27551496

  18. Imeglimin prevents human endothelial cell death by inhibiting mitochondrial permeability transition without inhibiting mitochondrial respiration

    PubMed Central

    Detaille, D; Vial, G; Borel, A-L; Cottet-Rouselle, C; Hallakou-Bozec, S; Bolze, S; Fouqueray, P; Fontaine, E

    2016-01-01

    Imeglimin is the first in a new class of oral glucose-lowering agents, having recently completed its phase 2b trial. As Imeglimin did show a full prevention of β-cell apoptosis, and since angiopathy represents a major complication of diabetes, we studied Imeglimin protective effects on hyperglycemia-induced death of human endothelial cells (HMEC-1). These cells were incubated in several oxidative stress environments (exposure to high glucose and oxidizing agent tert-butylhydroperoxide) which led to mitochondrial permeability transition pore (PTP) opening, cytochrome c release and cell death. These events were fully prevented by Imeglimin treatment. This protective effect on cell death occurred without any effect on oxygen consumption rate, on lactate production and on cytosolic redox or phosphate potentials. Imeglimin also dramatically decreased reactive oxygen species production, inhibiting specifically reverse electron transfer through complex I. We conclude that Imeglimin prevents hyperglycemia-induced cell death in HMEC-1 through inhibition of PTP opening without inhibiting mitochondrial respiration nor affecting cellular energy status. Considering the high prevalence of macrovascular and microvascular complications in type 2 diabetic subjects, these results together suggest a potential benefit of Imeglimin in diabetic angiopathy. PMID:27551496

  19. Nek5 interacts with mitochondrial proteins and interferes negatively in mitochondrial mediated cell death and respiration.

    PubMed

    Melo Hanchuk, Talita D; Papa, Priscila Ferreira; La Guardia, Paolo G; Vercesi, Anibal E; Kobarg, Jörg

    2015-06-01

    Mitochondria are involved in energy supply, signaling, cell death and cellular differentiation and have been implicated in several human diseases. Neks (NIMA-related kinases) represent a family of mammal protein kinases that play essential roles in cell-cycle progression, but other functions have recently been related. A yeast two-hybrid (Y2H) screen was performed to identify and characterize Nek5 interaction partners and the mitochondrial proteins Cox11, MTX-2 and BCLAF1 were retrieved. Apoptosis assay showed protective effects of stable hNek5 expression from Hek293-T's cell death after thapsigargin treatment (2 μM). Nek5 silenced cells as well as cells expressing a "kinase dead" version of Nek5, displayed an increase in ROS formation after 4 h of thapsigargin treatment. Mitochondrial respiratory chain activity was found decreased upon stable hNek5expression. Cells silenced for hNek5 on the other hand presented 1.7 fold increased basal rates of respiration, especially at the electrons transfer steps from TMPD to cytochrome c and at the complex II. In conclusion, our data suggest for the first time mitochondrial localization and functions for Nek5 and its participation in cell death and cell respiration regulation. Stable expression of hNek5 in Hek293T cells resulted in enhanced cell viability, decreased cell death and drug resistance, while depletion of hNek5by shRNA overcame cancer cell drug resistance and induced apoptosis in vitro. Stable expression of hNek5 also inhibits thapsigargin promoted apoptosis and the respiratory chain complex IV in HEK293T cells.

  20. Nek5 interacts with mitochondrial proteins and interferes negatively in mitochondrial mediated cell death and respiration.

    PubMed

    Melo Hanchuk, Talita D; Papa, Priscila Ferreira; La Guardia, Paolo G; Vercesi, Anibal E; Kobarg, Jörg

    2015-06-01

    Mitochondria are involved in energy supply, signaling, cell death and cellular differentiation and have been implicated in several human diseases. Neks (NIMA-related kinases) represent a family of mammal protein kinases that play essential roles in cell-cycle progression, but other functions have recently been related. A yeast two-hybrid (Y2H) screen was performed to identify and characterize Nek5 interaction partners and the mitochondrial proteins Cox11, MTX-2 and BCLAF1 were retrieved. Apoptosis assay showed protective effects of stable hNek5 expression from Hek293-T's cell death after thapsigargin treatment (2 μM). Nek5 silenced cells as well as cells expressing a "kinase dead" version of Nek5, displayed an increase in ROS formation after 4 h of thapsigargin treatment. Mitochondrial respiratory chain activity was found decreased upon stable hNek5expression. Cells silenced for hNek5 on the other hand presented 1.7 fold increased basal rates of respiration, especially at the electrons transfer steps from TMPD to cytochrome c and at the complex II. In conclusion, our data suggest for the first time mitochondrial localization and functions for Nek5 and its participation in cell death and cell respiration regulation. Stable expression of hNek5 in Hek293T cells resulted in enhanced cell viability, decreased cell death and drug resistance, while depletion of hNek5by shRNA overcame cancer cell drug resistance and induced apoptosis in vitro. Stable expression of hNek5 also inhibits thapsigargin promoted apoptosis and the respiratory chain complex IV in HEK293T cells. PMID:25725288

  1. ACCELERATED CELL DEATH2 suppresses mitochondrial oxidative bursts and modulates cell death in Arabidopsis

    PubMed Central

    Pattanayak, Gopal K.; Venkataramani, Sujatha; Hortensteiner, Stefan; Kunz, Lukas; Christ, Bastien; Moulin, Michael; Smith, Alison G.; Okamoto, Yukihiro; Tamiaki, Hitoshi; Sugishima, Masakazu; Greenberg, Jean T.

    2012-01-01

    SUMMARY The Arabidopsis ACCELERATED CELL DEATH 2 (ACD2) protein protects cells from programmed cell death (PCD) caused by endogenous porphyrin-related molecules like red chlorophyll catabolite or exogenous protoporphyrin IX. We previously found that during bacterial infection, ACD2, a chlorophyll breakdown enzyme, localizes to both chloroplasts and mitochondria in leaves. Additionally, acd2 cells show mitochondrial dysfunctions. In plants with acd2 and ACD2+ sectors, ACD2 functions cell autonomously, implicating a pro-death ACD2 substrate as cell non-autonomous in promoting spreading PCD. ACD2 targeted solely to mitochondria can reduce the accumulation of an ACD2 substrate that originates in chloroplasts, indicating that ACD2 substrate molecules are likely mobile within cells. Two different light-dependent reactive oxygen bursts in mitochondria play prominent and causal roles in the acd2 PCD phenotype. Finally, ACD2 can complement acd2 when targeted to mitochondria or chloroplasts, respectively, as long as it is catalytically active; the ability to bind substrate is not sufficient for ACD2 to function in vitro or in vivo. Together the data suggest that ACD2 localizes dynamically during infection to protect cells from pro-death mobile substrate molecules, some of which may originate in chloroplasts, but have major effects on mitochondria. PMID:21988537

  2. Accelerated cell death 2 suppresses mitochondrial oxidative bursts and modulates cell death in Arabidopsis.

    PubMed

    Pattanayak, Gopal K; Venkataramani, Sujatha; Hortensteiner, Stefan; Kunz, Lukas; Christ, Bastien; Moulin, Michael; Smith, Alison G; Okamoto, Yukihiro; Tamiaki, Hitoshi; Sugishima, Masakazu; Greenberg, Jean T

    2012-02-01

    The Arabidopsis ACCELERATED CELL DEATH 2 (ACD2) protein protects cells from programmed cell death (PCD) caused by endogenous porphyrin-related molecules like red chlorophyll catabolite or exogenous protoporphyrin IX. We previously found that during bacterial infection, ACD2, a chlorophyll breakdown enzyme, localizes to both chloroplasts and mitochondria in leaves. Additionally, acd2 cells show mitochondrial dysfunction. In plants with acd2 and ACD2 (+) sectors, ACD2 functions cell autonomously, implicating a pro-death ACD2 substrate as being cell non-autonomous in promoting the spread of PCD. ACD2 targeted solely to mitochondria can reduce the accumulation of an ACD2 substrate that originates in chloroplasts, indicating that ACD2 substrate molecules are likely to be mobile within cells. Two different light-dependent reactive oxygen bursts in mitochondria play prominent and causal roles in the acd2 PCD phenotype. Finally, ACD2 can complement acd2 when targeted to mitochondria or chloroplasts, respectively, as long as it is catalytically active: the ability to bind substrate is not sufficient for ACD2 to function in vitro or in vivo. Together, the data suggest that ACD2 localizes dynamically during infection to protect cells from pro-death mobile substrate molecules, some of which may originate in chloroplasts, but have major effects on mitochondria.

  3. Loss of cyclophilin D reveals a critical role for mitochondrial permeability transition in cell death.

    PubMed

    Baines, Christopher P; Kaiser, Robert A; Purcell, Nicole H; Blair, N Scott; Osinska, Hanna; Hambleton, Michael A; Brunskill, Eric W; Sayen, M Richard; Gottlieb, Roberta A; Dorn, Gerald W; Robbins, Jeffrey; Molkentin, Jeffery D

    2005-03-31

    Mitochondria play a critical role in mediating both apoptotic and necrotic cell death. The mitochondrial permeability transition (mPT) leads to mitochondrial swelling, outer membrane rupture and the release of apoptotic mediators. The mPT pore is thought to consist of the adenine nucleotide translocator, a voltage-dependent anion channel, and cyclophilin D (the Ppif gene product), a prolyl isomerase located within the mitochondrial matrix. Here we generated mice lacking Ppif and mice overexpressing cyclophilin D in the heart. Ppif null mice are protected from ischaemia/reperfusion-induced cell death in vivo, whereas cyclophilin D-overexpressing mice show mitochondrial swelling and spontaneous cell death. Mitochondria isolated from the livers, hearts and brains of Ppif null mice are resistant to mitochondrial swelling and permeability transition in vitro. Moreover, primary hepatocytes and fibroblasts isolated from Ppif null mice are largely protected from Ca2+-overload and oxidative stress-induced cell death. However, Bcl-2 family member-induced cell death does not depend on cyclophilin D, and Ppif null fibroblasts are not protected from staurosporine or tumour-necrosis factor-alpha-induced death. Thus, cyclophilin D and the mitochondrial permeability transition are required for mediating Ca2+- and oxidative damage-induced cell death, but not Bcl-2 family member-regulated death. PMID:15800627

  4. Mitochondrial calcium uniporter protein MCU is involved in oxidative stress-induced cell death.

    PubMed

    Liao, Yajin; Hao, Yumin; Chen, Hong; He, Qing; Yuan, Zengqiang; Cheng, Jinbo

    2015-06-01

    Mitochondrial calcium uniporter (MCU) is a conserved Ca(2+) transporter at mitochondrial in eukaryotic cells. However, the role of MCU protein in oxidative stress-induced cell death remains unclear. Here, we showed that ectopically expressed MCU is mitochondrial localized in both HeLa and primary cerebellar granule neurons (CGNs). Knockdown of endogenous MCU decreases mitochondrial Ca(2+) uptake following histamine stimulation and attenuates cell death induced by oxidative stress in both HeLa cells and CGNs. We also found MCU interacts with VDAC1 and mediates VDAC1 overexpression-induced cell death in CGNs. This finding demonstrates that MCU-VDAC1 complex regulates mitochondrial Ca(2+) uptake and oxidative stress-induced apoptosis, which might represent therapeutic targets for oxidative stress related diseases.

  5. The Mitochondrial Fission Regulator DRP3B Does Not Regulate Cell Death in Plants

    PubMed Central

    YOSHINAGA, KEIKO; FUJIMOTO, MASARU; ARIMURA, SHIN-ICHI; TSUTSUMI, NOBUHIRO; UCHIMIYA, HIROFUMI; KAWAI-YAMADA, MAKI

    2006-01-01

    • Background and Aims Recent reports have described dramatic alterations in mitochondrial morphology during metazoan apoptosis. A dynamin-related protein (DRP) associated with mitochondrial outer membrane fission is known to be involved in the regulation of apoptosis. This study analysed the relationship between mitochondrial fission and regulation of plant cell death. • Methods Transgenic plants were generated possessing Arabidopsis DRP3B (K56A), the dominant-negative form of Arabidopsis DRP, mitochondrial-targeted green fluorescent protein and mouse Bax. • Key Results Arabidopsis plants over-expressing DRP3B (K56A) exhibited long tubular mitochondria. In these plants, mitochondria appeared as a string-of-beads during cell death. This indicates that DRP3B (K56A) prevented mitochondrial fission during plant cell death. However, in contrast to results for mammalian cells and yeast, Bax-induced cell death was not inhibited in DRP3B (K56A)-expressing plant cells. Similarly, hydrogen peroxide-, menadione-, darkness- and salicylic acid-induced cell death was not inhibited by DRP3B (K56A) expression. • Conclusions These results indicate that the systems controlling cell death in animals and plants are not common in terms of mitochondrial fission. PMID:16533833

  6. Mitochondrial complex I and cell death: a semi-automatic shotgun model

    PubMed Central

    Gonzalez-Halphen, D; Ghelli, A; Iommarini, L; Carelli, V; Esposti, M D

    2011-01-01

    Mitochondrial dysfunction often leads to cell death and disease. We can now draw correlations between the dysfunction of one of the most important mitochondrial enzymes, NADH:ubiquinone reductase or complex I, and its structural organization thanks to the recent advances in the X-ray structure of its bacterial homologs. The new structural information on bacterial complex I provide essential clues to finally understand how complex I may work. However, the same information remains difficult to interpret for many scientists working on mitochondrial complex I from different angles, especially in the field of cell death. Here, we present a novel way of interpreting the bacterial structural information in accessible terms. On the basis of the analogy to semi-automatic shotguns, we propose a novel functional model that incorporates recent structural information with previous evidence derived from studies on mitochondrial diseases, as well as functional bioenergetics. PMID:22030538

  7. Human lactoferrin triggers a mitochondrial- and caspase-dependent regulated cell death in Saccharomyces cerevisiae.

    PubMed

    Acosta-Zaldívar, M; Andrés, M T; Rego, A; Pereira, C S; Fierro, J F; Côrte-Real, M

    2016-02-01

    We have previously shown that the antifungal activity of human lactoferrin (hLf) against Candida albicans relies on its ability to induce cell death associated with apoptotic markers. To gain a deeper understanding of the mechanisms underlying hLf-induced apoptosis, we characterized this cell death process in the well-established Saccharomyces cerevisiae model. Our results indicate that hLf induces cell death in S. cerevisiae in a manner that requires energy and de novo protein synthesis. Cell death is associated with nuclear chromatin condensation, preservation of plasma membrane integrity, and is Yca1p metacaspase-dependent. Lactoferrin also caused mitochondrial dysfunction associated with ROS accumulation and release of cytochrome c. Pre-incubation with oligomycin, an oxidative phosphorylation inhibitor, increased resistance to hLf and, accordingly, mutants deficient in the F1F0-ATP synthase complex were more resistant to death induced by hLf. This indicates that mitochondrial energetic metabolism plays a key role in the killing effect of hLf, though a direct role of F1F0-ATP synthase cannot be precluded. Overexpression of the anti-apoptotic protein Bcl-xL or pre-incubation with N-acetyl cysteine reduced the intracellular level of ROS and increased resistance to hLf, confirming a ROS-mediated mitochondrial cell death process. Mitochondrial involvement was further reinforced by the higher resistance of cells lacking mitochondrial DNA, or other known yeast mitochondrial apoptosis regulators, such as, Aif1p, Cyc3p and Aac1/2/3p. This study provides new insights into a detailed understanding at the molecular level of hLf-induced apoptosis, which may allow the design of new strategies to overcome the emergence of resistance of clinically relevant fungi to conventional antifungals.

  8. A cardiac mitochondrial cAMP signaling pathway regulates calcium accumulation, permeability transition and cell death

    PubMed Central

    Wang, Z; Liu, D; Varin, A; Nicolas, V; Courilleau, D; Mateo, P; Caubere, C; Rouet, P; Gomez, A-M; Vandecasteele, G; Fischmeister, R; Brenner, C

    2016-01-01

    Although cardiac cytosolic cyclic 3′,5′-adenosine monophosphate (cAMP) regulates multiple processes, such as beating, contractility, metabolism and apoptosis, little is known yet on the role of this second messenger within cardiac mitochondria. Using cellular and subcellular approaches, we demonstrate here the local expression of several actors of cAMP signaling within cardiac mitochondria, namely a truncated form of soluble AC (sACt) and the exchange protein directly activated by cAMP 1 (Epac1), and show a protective role for sACt against cell death, apoptosis as well as necrosis in primary cardiomyocytes. Upon stimulation with bicarbonate (HCO3−) and Ca2+, sACt produces cAMP, which in turn stimulates oxygen consumption, increases the mitochondrial membrane potential (ΔΨm) and ATP production. cAMP is rate limiting for matrix Ca2+ entry via Epac1 and the mitochondrial calcium uniporter and, as a consequence, prevents mitochondrial permeability transition (MPT). The mitochondrial cAMP effects involve neither protein kinase A, Epac2 nor the mitochondrial Na+/Ca2+ exchanger. In addition, in mitochondria isolated from failing rat hearts, stimulation of the mitochondrial cAMP pathway by HCO3− rescued the sensitization of mitochondria to Ca2+-induced MPT. Thus, our study identifies a link between mitochondrial cAMP, mitochondrial metabolism and cell death in the heart, which is independent of cytosolic cAMP signaling. Our results might have implications for therapeutic prevention of cell death in cardiac pathologies. PMID:27100892

  9. Pepper mitochondrial FORMATE DEHYDROGENASE1 regulates cell death and defense responses against bacterial pathogens.

    PubMed

    Choi, Du Seok; Kim, Nak Hyun; Hwang, Byung Kook

    2014-11-01

    Formate dehydrogenase (FDH; EC 1.2.1.2) is an NAD-dependent enzyme that catalyzes the oxidation of formate to carbon dioxide. Here, we report the identification and characterization of pepper (Capsicum annuum) mitochondrial FDH1 as a positive regulator of cell death and defense responses. Transient expression of FDH1 caused hypersensitive response (HR)-like cell death in pepper and Nicotiana benthamiana leaves. The D-isomer -: specific 2-hydroxyacid dehydrogenase signatures of FDH1 were required for the induction of HR-like cell death and FDH activity. FDH1 contained a mitochondrial targeting sequence at the N-terminal region; however, mitochondrial localization of FDH1 was not essential for the induction of HR-like cell death and FDH activity. FDH1 silencing in pepper significantly attenuated the cell death response and salicylic acid levels but stimulated growth of Xanthomonas campestris pv vesicatoria. By contrast, transgenic Arabidopsis (Arabidopsis thaliana) overexpressing FDH1 exhibited greater resistance to Pseudomonas syringae pv tomato in a salicylic acid-dependent manner. Arabidopsis transfer DNA insertion mutant analysis indicated that AtFDH1 expression is required for basal defense and resistance gene-mediated resistance to P. syringae pv tomato infection. Taken together, these data suggest that FDH1 has an important role in HR-like cell death and defense responses to bacterial pathogens.

  10. Evolution of mitochondrial cell death pathway: Proapoptotic role of HtrA2/Omi in Drosophila

    SciTech Connect

    Igaki, Tatsushi; Suzuki, Yasuyuki; Tokushige, Naoko; Aonuma, Hiroka; Takahashi, Ryosuke . E-mail: ryosuket@kuhp.kyoto-u.ac.jp; Miura, Masayuki . E-mail: miura@mol.f.u-tokyo.ac.jp

    2007-05-18

    Despite the essential role of mitochondria in a variety of mammalian cell death processes, the involvement of mitochondrial pathway in Drosophila cell death has remained unclear. To address this, we cloned and characterized DmHtrA2, a Drosophila homolog of a mitochondrial serine protease HtrA2/Omi. We show that DmHtrA2 normally resides in mitochondria and is up-regulated by UV-irradiation. Upon receipt of apoptotic stimuli, DmHtrA2 is translocated to extramitochondrial compartment; however, unlike its mammalian counterpart, the extramitochondrial DmHtrA2 does not diffuse throughout the cytosol but stays near the mitochondria. RNAi-mediated knock-down of DmHtrA2 in larvae or adult flies results in a resistance to stress stimuli. DmHtrA2 specifically cleaves Drosophila inhibitor-of-apoptosis protein 1 (DIAP1), a cellular caspase inhibitor, and induces cell death both in vitro and in vivo as potent as other fly cell death proteins. Our observations suggest that DmHtrA2 promotes cell death through a cleavage of DIAP1 in the vicinity of mitochondria, which may represent a prototype of mitochondrial cell death pathway in evolution.

  11. Mitochondrial localization of TIGAR under hypoxia stimulates HK2 and lowers ROS and cell death.

    PubMed

    Cheung, Eric C; Ludwig, Robert L; Vousden, Karen H

    2012-12-11

    The p53-inducible protein TIGAR (Tp53-induced Glycolysis and Apoptosis Regulator) functions as a fructose-2,6-bisphosphatase (Fru-2,6-BPase), and through promotion of the pentose phosphate pathway, increases NADPH production to help limit reactive oxygen species (ROS). Here, we show that under hypoxia, a fraction of TIGAR protein relocalized to mitochondria and formed a complex with hexokinase 2 (HK2), resulting in an increase in HK2 activity. Mitochondrial localization of TIGAR depended on mitochondrial HK2 and hypoxia-inducible factor 1 (HIF1α) activity. The ability of TIGAR to function as a Fru-2,6-BPase was independent of HK2 binding and mitochondrial localization, although both of these activities can contribute to the full activity of TIGAR in limiting mitochondrial ROS levels and protecting from cell death.

  12. Thioredoxin Reductase Deficiency Potentiates Oxidative Stress, Mitochondrial Dysfunction and Cell Death in Dopaminergic Cells

    PubMed Central

    Lopert, Pamela; Day, Brian J.; Patel, Manisha

    2012-01-01

    Mitochondria are considered major generators of cellular reactive oxygen species (ROS) which are implicated in the pathogenesis of neurodegenerative diseases such as Parkinson’s disease (PD). We have recently shown that isolated mitochondria consume hydrogen peroxide (H2O2) in a substrate- and respiration-dependent manner predominantly via the thioredoxin/peroxiredoxin (Trx/Prx) system. The goal of this study was to determine the role of Trx/Prx system in dopaminergic cell death. We asked if pharmacological and lentiviral inhibition of the Trx/Prx system sensitized dopaminergic cells to mitochondrial dysfunction, increased steady-state H2O2 levels and death in response to toxicants implicated in PD. Incubation of N27 dopaminergic cells or primary rat mesencephalic cultures with the Trx reductase (TrxR) inhibitor auranofin in the presence of sub-toxic concentrations of parkinsonian toxicants paraquat; PQ or 6-hydroxydopamine; 6OHDA (for N27 cells) resulted in a synergistic increase in H2O2 levels and subsequent cell death. shRNA targeting the mitochondrial thioredoxin reductase (TrxR2) in N27 cells confirmed the effects of pharmacological inhibition. A synergistic decrease in maximal and reserve respiratory capacity was observed in auranofin treated cells and TrxR2 deficient cells following incubation with PQ or 6OHDA. Additionally, TrxR2 deficient cells showed decreased basal mitochondrial oxygen consumption rates. These data demonstrate that inhibition of the mitochondrial Trx/Prx system sensitizes dopaminergic cells to mitochondrial dysfunction, increased steady-state H2O2, and cell death. Therefore, in addition to their role in the production of cellular H2O2 the mitochondrial Trx/Prx system serve as a major sink for cellular H2O2 and its disruption may contribute to dopaminergic pathology associated with PD. PMID:23226354

  13. Life and Death Decision Making, by Baruch A. Brody.

    PubMed

    Veatch, Robert M

    1989-04-01

    Veatch considers the pluralistic casuistry theory advocated by Baruch Brody in his 1988 book, Life and Death Decision Making, to be an important contribution to the secular medical ethics literature. The casuistic and pluralistic elements of Brody's new model are described as intriguing but controversial because Brody both excludes several ethical appeals (i.e., classical Hippocratic ethics, virtue theory) and/or limits other questionable appeals (i.e., consequences for families and others in society, the virtue of integrity) without accounting for these decisions. Veatch also questions Brody's use of intuitional judgment to determine what ought to be done after examination of various appeals and their significance because Brody's approach raises serious problems about how various appeals are counted. Veatch does affirm the rich assessment of medical ethical problems made possible by Brody's pluralistic approach but notes the difficulties it raises. PMID:11649246

  14. Mitochondrial calcium uptake underlies ROS generation during aminoglycoside-induced hair cell death.

    PubMed

    Esterberg, Robert; Linbo, Tor; Pickett, Sarah B; Wu, Patricia; Ou, Henry C; Rubel, Edwin W; Raible, David W

    2016-09-01

    Exposure to aminoglycoside antibiotics can lead to the generation of toxic levels of reactive oxygen species (ROS) within mechanosensory hair cells of the inner ear that have been implicated in hearing and balance disorders. Better understanding of the origin of aminoglycoside-induced ROS could focus the development of therapies aimed at preventing this event. In this work, we used the zebrafish lateral line system to monitor the dynamic behavior of mitochondrial and cytoplasmic oxidation occurring within the same dying hair cell following exposure to aminoglycosides. The increased oxidation observed in both mitochondria and cytoplasm of dying hair cells was highly correlated with mitochondrial calcium uptake. Application of the mitochondrial uniporter inhibitor Ru360 reduced mitochondrial and cytoplasmic oxidation, suggesting that mitochondrial calcium drives ROS generation during aminoglycoside-induced hair cell death. Furthermore, targeting mitochondria with free radical scavengers conferred superior protection against aminoglycoside exposure compared with identical, untargeted scavengers. Our findings suggest that targeted therapies aimed at preventing mitochondrial oxidation have therapeutic potential to ameliorate the toxic effects of aminoglycoside exposure. PMID:27500493

  15. Human-Gyrovirus-Apoptin Triggers Mitochondrial Death Pathway—Nur77 is Required for Apoptosis Triggering

    PubMed Central

    Chaabane, Wiem; Cieślar-Pobuda, Artur; El-Gazzah, Mohamed; Jain, Mayur V.; Rzeszowska-Wolny, Joanna; Rafat, Mehrdad; Stetefeld, Joerg; Ghavami, Saeid; Łos, Marek J.

    2014-01-01

    The human gyrovirus derived protein Apoptin (HGV-Apoptin) a homologue of the chicken anemia virus Apoptin (CAV-Apoptin), a protein with high cancer cells selective toxicity, triggers apoptosis selectively in cancer cells. In this paper, we show that HGV-Apoptin acts independently from the death receptor pathway as it induces apoptosis in similar rates in Jurkat cells deficient in either FADD (fas-associated death domain) function or caspase-8 (key players of the extrinsic pathway) and their parental clones. HGV-Apoptin induces apoptosis via the activation of the mitochondrial intrinsic pathway. It induces both mitochondrial inner and outer membrane permebilization, characterized by the loss of the mitochondrial potential and the release into cytoplasm of the pro-apoptotic molecules including apoptosis inducing factor and cytochrome c. HGV-Apoptin acts via the apoptosome, as lack of expression of apoptotic protease-activating factor 1 in murine embryonic fibroblast strongly protected the cells from HGV-Apoptin–induced apoptosis. Moreover, QVD-oph a broad-spectrum caspase inhibitor delayed HGV-Apoptin–induced death. On the other hand, overexpression of the anti-apoptotic BCL-XL confers resistance to HGV-Apoptin–induced cell death. In contrast, cells that lack the expression of the pro-apoptotic BAX and BAK are protected from HGV-Apoptin induced apoptosis. Furthermore, HGV-Apoptin acts independently from p53 signal but triggers the cytoplasmic translocation of Nur77. Taking together these data indicate that HGV-Apoptin acts through the mitochondrial pathway, in a caspase-dependent manner but independently from the death receptor pathway. PMID:25246270

  16. Cdk1, PKCδ and calcineurin-mediated Drp1 pathway contributes to mitochondrial fission-induced cardiomyocyte death

    SciTech Connect

    Zaja, Ivan; Bai, Xiaowen; Liu, Yanan; Kikuchi, Chika; Dosenovic, Svjetlana; Yan, Yasheng; Canfield, Scott G.; Bosnjak, Zeljko J.

    2014-10-31

    Highlights: • Drp1-mediated increased mitochondrial fission but not fusion is involved the cardiomyocyte death during anoxia-reoxygenation injury. • Reactive oxygen species are upstream initiators of mitochondrial fission. • Increased mitochondrial fission is resulted from Cdk1-, PKCδ-, and calcineurin-mediated Drp1 pathways. - Abstract: Myocardial ischemia–reperfusion (I/R) injury is one of the leading causes of death and disability worldwide. Mitochondrial fission has been shown to be involved in cardiomyocyte death. However, molecular machinery involved in mitochondrial fission during I/R injury has not yet been completely understood. In this study we aimed to investigate molecular mechanisms of controlling activation of dynamin-related protein 1 (Drp1, a key protein in mitochondrial fission) during anoxia-reoxygenation (A/R) injury of HL1 cardiomyocytes. A/R injury induced cardiomyocyte death accompanied by the increases of mitochondrial fission, reactive oxygen species (ROS) production and activated Drp1 (pSer616 Drp1), and decrease of inactivated Drp1 (pSer637 Drp1) while mitochondrial fusion protein levels were not significantly changed. Blocking Drp1 activity with mitochondrial division inhibitor mdivi1 attenuated cell death, mitochondrial fission, and Drp1 activation after A/R. Trolox, a ROS scavenger, decreased pSer616 Drp1 level and mitochondrial fission after A/R. Immunoprecipitation assay further indicates that cyclin dependent kinase 1 (Cdk1) and protein kinase C isoform delta (PKCδ) bind Drp1, thus increasing mitochondrial fission. Inhibiting Cdk1 and PKCδ attenuated the increases in pSer616 Drp1, mitochondrial fission, and cardiomyocyte death. FK506, a calcineurin inhibitor, blocked the decrease in expression of inactivated pSer637 Drp1 and mitochondrial fission. Our findings reveal the following novel molecular mechanisms controlling mitochondrial fission during A/R injury of cardiomyocytes: (1) ROS are upstream initiators of

  17. Arginine starvation-associated atypical cellular death involves mitochondrial dysfunction, nuclear DNA leakage, and chromatin autophagy

    PubMed Central

    Changou, Chun A.; Chen, Yun-Ru; Xing, Li; Yen, Yun; Chuang, Frank Y. S.; Cheng, R. Holland; Bold, Richard J.; Ann, David K.; Kung, Hsing-Jien

    2014-01-01

    Autophagy is the principal catabolic prosurvival pathway during nutritional starvation. However, excessive autophagy could be cytotoxic, contributing to cell death, but its mechanism remains elusive. Arginine starvation has emerged as a potential therapy for several types of cancers, owing to their tumor-selective deficiency of the arginine metabolism. We demonstrated here that arginine depletion by arginine deiminase induces a cytotoxic autophagy in argininosuccinate synthetase (ASS1)-deficient prostate cancer cells. Advanced microscopic analyses of arginine-deprived dying cells revealed a novel phenotype with giant autophagosome formation, nucleus membrane rupture, and histone-associated DNA leakage encaptured by autophagosomes, which we shall refer to as chromatin autophagy, or chromatophagy. In addition, nuclear inner membrane (lamin A/C) underwent localized rearrangement and outer membrane (NUP98) partially fused with autophagosome membrane. Further analysis showed that prolonged arginine depletion impaired mitochondrial oxidative phosphorylation function and depolarized mitochondrial membrane potential. Thus, reactive oxygen species (ROS) production significantly increased in both cytosolic and mitochondrial fractions, presumably leading to DNA damage accumulation. Addition of ROS scavenger N-acetyl cysteine or knockdown of ATG5 or BECLIN1 attenuated the chromatophagy phenotype. Our data uncover an atypical autophagy-related death pathway and suggest that mitochondrial damage is central to linking arginine starvation and chromatophagy in two distinct cellular compartments. PMID:25122679

  18. Arginine starvation-associated atypical cellular death involves mitochondrial dysfunction, nuclear DNA leakage, and chromatin autophagy.

    PubMed

    Changou, Chun A; Chen, Yun-Ru; Xing, Li; Yen, Yun; Chuang, Frank Y S; Cheng, R Holland; Bold, Richard J; Ann, David K; Kung, Hsing-Jien

    2014-09-30

    Autophagy is the principal catabolic prosurvival pathway during nutritional starvation. However, excessive autophagy could be cytotoxic, contributing to cell death, but its mechanism remains elusive. Arginine starvation has emerged as a potential therapy for several types of cancers, owing to their tumor-selective deficiency of the arginine metabolism. We demonstrated here that arginine depletion by arginine deiminase induces a cytotoxic autophagy in argininosuccinate synthetase (ASS1)-deficient prostate cancer cells. Advanced microscopic analyses of arginine-deprived dying cells revealed a novel phenotype with giant autophagosome formation, nucleus membrane rupture, and histone-associated DNA leakage encaptured by autophagosomes, which we shall refer to as chromatin autophagy, or chromatophagy. In addition, nuclear inner membrane (lamin A/C) underwent localized rearrangement and outer membrane (NUP98) partially fused with autophagosome membrane. Further analysis showed that prolonged arginine depletion impaired mitochondrial oxidative phosphorylation function and depolarized mitochondrial membrane potential. Thus, reactive oxygen species (ROS) production significantly increased in both cytosolic and mitochondrial fractions, presumably leading to DNA damage accumulation. Addition of ROS scavenger N-acetyl cysteine or knockdown of ATG5 or BECLIN1 attenuated the chromatophagy phenotype. Our data uncover an atypical autophagy-related death pathway and suggest that mitochondrial damage is central to linking arginine starvation and chromatophagy in two distinct cellular compartments.

  19. Sudden Cardiac Death Due to Deficiency of the Mitochondrial Inorganic Pyrophosphatase PPA2.

    PubMed

    Kennedy, Hannah; Haack, Tobias B; Hartill, Verity; Mataković, Lavinija; Baumgartner, E Regula; Potter, Howard; Mackay, Richard; Alston, Charlotte L; O'Sullivan, Siobhan; McFarland, Robert; Connolly, Grainne; Gannon, Caroline; King, Richard; Mead, Scott; Crozier, Ian; Chan, Wandy; Florkowski, Chris M; Sage, Martin; Höfken, Thomas; Alhaddad, Bader; Kremer, Laura S; Kopajtich, Robert; Feichtinger, René G; Sperl, Wolfgang; Rodenburg, Richard J; Minet, Jean Claude; Dobbie, Angus; Strom, Tim M; Meitinger, Thomas; George, Peter M; Johnson, Colin A; Taylor, Robert W; Prokisch, Holger; Doudney, Kit; Mayr, Johannes A

    2016-09-01

    We have used whole-exome sequencing in ten individuals from four unrelated pedigrees to identify biallelic missense mutations in the nuclear-encoded mitochondrial inorganic pyrophosphatase (PPA2) that are associated with mitochondrial disease. These individuals show a range of severity, indicating that PPA2 mutations may cause a spectrum of mitochondrial disease phenotypes. Severe symptoms include seizures, lactic acidosis, cardiac arrhythmia, and death within days of birth. In the index family, presentation was milder and manifested as cardiac fibrosis and an exquisite sensitivity to alcohol, leading to sudden arrhythmic cardiac death in the second decade of life. Comparison of normal and mutant PPA2-containing mitochondria from fibroblasts showed that the activity of inorganic pyrophosphatase was significantly reduced in affected individuals. Recombinant PPA2 enzymes modeling hypomorphic missense mutations had decreased activity that correlated with disease severity. These findings confirm the pathogenicity of PPA2 mutations and suggest that PPA2 is a cardiomyopathy-associated protein, which has a greater physiological importance in mitochondrial function than previously recognized. PMID:27523597

  20. The Differential DRP1 Phosphorylation and Mitochondrial Dynamics in the Regional Specific Astroglial Death Induced by Status Epilepticus.

    PubMed

    Ko, Ah-Reum; Hyun, Hye-Won; Min, Su-Ji; Kim, Ji-Eun

    2016-01-01

    The response and susceptibility to astroglial degenerations are relevant to the distinctive properties of astrocytes in a hemodynamic-independent manner following status epilepticus (SE). Since impaired mitochondrial fission plays an important role in mitosis, apoptosis and programmed necrosis, we investigated whether the unique pattern of mitochondrial dynamics is involved in the characteristics of astroglial death induced by SE. In the present study, SE induced astroglial apoptosis in the molecular layer of the dentate gyrus, accompanied by decreased mitochondrial length. In contrast, clasmatodendritic (autophagic) astrocytes in the CA1 region showed mitochondrial elongation induced by SE. Mdivi-1 (an inhibitor of mitochondrial fission) effectively attenuated astroglial apoptosis, but WY14643 (an enhancer of mitochondrial fission) aggravated it. In addition, Mdivi-1 accelerated clasmatodendritic changes in astrocytes. These regional specific mitochondrial dynamics in astrocytes were closely correlated with dynamin-related protein 1 (DRP1; a mitochondrial fission protein) phosphorylation, not optic atrophy 1 (OPA1; a mitochondrial fusion protein) expression. To the best of our knowledge, the present data demonstrate for the first time the novel role of DRP1-mediated mitochondrial fission in astroglial loss. Thus, the present findings suggest that the differential astroglial mitochondrial dynamics may participate in the distinct characteristics of astroglial death induced by SE.

  1. The Differential DRP1 Phosphorylation and Mitochondrial Dynamics in the Regional Specific Astroglial Death Induced by Status Epilepticus

    PubMed Central

    Ko, Ah-Reum; Hyun, Hye-Won; Min, Su-Ji; Kim, Ji-Eun

    2016-01-01

    The response and susceptibility to astroglial degenerations are relevant to the distinctive properties of astrocytes in a hemodynamic-independent manner following status epilepticus (SE). Since impaired mitochondrial fission plays an important role in mitosis, apoptosis and programmed necrosis, we investigated whether the unique pattern of mitochondrial dynamics is involved in the characteristics of astroglial death induced by SE. In the present study, SE induced astroglial apoptosis in the molecular layer of the dentate gyrus, accompanied by decreased mitochondrial length. In contrast, clasmatodendritic (autophagic) astrocytes in the CA1 region showed mitochondrial elongation induced by SE. Mdivi-1 (an inhibitor of mitochondrial fission) effectively attenuated astroglial apoptosis, but WY14643 (an enhancer of mitochondrial fission) aggravated it. In addition, Mdivi-1 accelerated clasmatodendritic changes in astrocytes. These regional specific mitochondrial dynamics in astrocytes were closely correlated with dynamin-related protein 1 (DRP1; a mitochondrial fission protein) phosphorylation, not optic atrophy 1 (OPA1; a mitochondrial fusion protein) expression. To the best of our knowledge, the present data demonstrate for the first time the novel role of DRP1-mediated mitochondrial fission in astroglial loss. Thus, the present findings suggest that the differential astroglial mitochondrial dynamics may participate in the distinct characteristics of astroglial death induced by SE. PMID:27242436

  2. The mitochondrial permeability transition pore and its role in cell death.

    PubMed Central

    Crompton, M

    1999-01-01

    This article reviews the involvement of the mitochondrial permeability transition pore in necrotic and apoptotic cell death. The pore is formed from a complex of the voltage-dependent anion channel (VDAC), the adenine nucleotide translocase and cyclophilin-D (CyP-D) at contact sites between the mitochondrial outer and inner membranes. In vitro, under pseudopathological conditions of oxidative stress, relatively high Ca2+ and low ATP, the complex flickers into an open-pore state allowing free diffusion of low-Mr solutes across the inner membrane. These conditions correspond to those that unfold during tissue ischaemia and reperfusion, suggesting that pore opening may be an important factor in the pathogenesis of necrotic cell death following ischaemia/reperfusion. Evidence that the pore does open during ischaemia/reperfusion is discussed. There are also strong indications that the VDAC-adenine nucleotide translocase-CyP-D complex can recruit a number of other proteins, including Bax, and that the complex is utilized in some capacity during apoptosis. The apoptotic pathway is amplified by the release of apoptogenic proteins from the mitochondrial intermembrane space, including cytochrome c, apoptosis-inducing factor and some procaspases. Current evidence that the pore complex is involved in outer-membrane rupture and release of these proteins during programmed cell death is reviewed, along with indications that transient pore opening may provoke 'accidental' apoptosis. PMID:10393078

  3. The mitochondrial and death receptor pathways involved in the thymocytes apoptosis induced by aflatoxin B1

    PubMed Central

    Chi, Xiaofeng; Li, Xiaochong; Jiang, Min; Fang, Jing; Cui, Hengmin; Lai, Weimin; Zhou, Yi; Zhou, Shan

    2016-01-01

    Aflatoxin B1 (AFB1) is a potent immunosuppressive agent in endotherms, which can be related to the up-regulated apoptosis of immune organs. In this study, we investigated the roles of the mitochondrial, death receptor, and endoplasmic reticulum pathways in Aflatoxin B1 induced thymocytes apoptosis. Chickens were fed an aflatoxin B1 containing diet (0.6 mg/kg AFB1) for 3 weeks. Our results showed that (1) AFB1 diet induced the decrease of T-cell subsets, morphological changes, and excessive apoptosis of thymus. (2) The excessive apoptosis involved the mitochondrial pathway (up-regulation of Bax, Bak, cytC and down-regulation of Bcl-2 and Bcl-xL) and death receptor pathway (up-regulation of FasL, Fas and FADD). (3) Oxidative stress, an apoptosis inducer, was confirmed in the thymus. In conclusion, this is the first study to demonstrate that mitochondrial and death receptor pathways involved in AFB1 induced thymocytes apoptosis in broilers. PMID:26933817

  4. 'Mitochondrial energy imbalance and lipid peroxidation cause cell death in Friedreich's ataxia'

    PubMed Central

    Abeti, R; Parkinson, M H; Hargreaves, I P; Angelova, P R; Sandi, C; Pook, M A; Giunti, P; Abramov, A Y

    2016-01-01

    Friedreich's ataxia (FRDA) is an inherited neurodegenerative disease. The mutation consists of a GAA repeat expansion within the FXN gene, which downregulates frataxin, leading to abnormal mitochondrial iron accumulation, which may in turn cause changes in mitochondrial function. Although, many studies of FRDA patients and mouse models have been conducted in the past two decades, the role of frataxin in mitochondrial pathophysiology remains elusive. Are the mitochondrial abnormalities only a side effect of the increased accumulation of reactive iron, generating oxidative stress? Or does the progressive lack of iron-sulphur clusters (ISCs), induced by reduced frataxin, cause an inhibition of the electron transport chain complexes (CI, II and III) leading to reactive oxygen species escaping from oxidative phosphorylation reactions? To answer these crucial questions, we have characterised the mitochondrial pathophysiology of a group of disease-relevant and readily accessible neurons, cerebellar granule cells, from a validated FRDA mouse model. By using live cell imaging and biochemical techniques we were able to demonstrate that mitochondria are deregulated in neurons from the YG8R FRDA mouse model, causing a decrease in mitochondrial membrane potential (▵Ψm) due to an inhibition of Complex I, which is partially compensated by an overactivation of Complex II. This complex activity imbalance leads to ROS generation in both mitochondrial matrix and cytosol, which results in glutathione depletion and increased lipid peroxidation. Preventing this increase in lipid peroxidation, in neurons, protects against in cell death. This work describes the pathophysiological properties of the mitochondria in neurons from a FRDA mouse model and shows that lipid peroxidation could be an important target for novel therapeutic strategies in FRDA, which still lacks a cure. PMID:27228352

  5. In EXOG-depleted cardiomyocytes cell death is marked by a decreased mitochondrial reserve capacity of the electron transport chain.

    PubMed

    Tigchelaar, Wardit; De Jong, Anne Margreet; van Gilst, Wiek H; De Boer, Rudolf A; Silljé, Herman H W

    2016-07-01

    Depletion of mitochondrial endo/exonuclease G-like (EXOG) in cultured neonatal cardiomyocytes stimulates mitochondrial oxygen consumption rate (OCR) and induces hypertrophy via reactive oxygen species (ROS). Here, we show that neurohormonal stress triggers cell death in endo/exonuclease G-like-depleted cells, and this is marked by a decrease in mitochondrial reserve capacity. Neurohormonal stimulation with phenylephrine (PE) did not have an additive effect on the hypertrophic response induced by endo/exonuclease G-like depletion. Interestingly, PE-induced atrial natriuretic peptide (ANP) gene expression was completely abolished in endo/exonuclease G-like-depleted cells, suggesting a reverse signaling function of endo/exonuclease G-like. Endo/exonuclease G-like depletion initially resulted in increased mitochondrial OCR, but this declined upon PE stimulation. In particular, the reserve capacity of the mitochondrial respiratory chain and maximal respiration were the first indicators of perturbations in mitochondrial respiration, and these marked the subsequent decline in mitochondrial function. Although pathological stimulation accelerated these processes, prolonged EXOG depletion also resulted in a decline in mitochondrial function. At early stages of endo/exonuclease G-like depletion, mitochondrial ROS production was increased, but this did not affect mitochondrial DNA (mtDNA) integrity. After prolonged depletion, ROS levels returned to control values, despite hyperpolarization of the mitochondrial membrane. The mitochondrial dysfunction finally resulted in cell death, which appears to be mainly a form of necrosis. In conclusion, endo/exonuclease G-like plays an essential role in cardiomyocyte physiology. Loss of endo/exonuclease G-like results in diminished adaptation to pathological stress. The decline in maximal respiration and reserve capacity is the first sign of mitochondrial dysfunction that determines subsequent cell death. PMID:27417117

  6. Bnip3 mediates mitochondrial dysfunction and cell death through Bax and Bak

    PubMed Central

    Kubli, Dieter A.; Ycaza, John E.; Gustafsson, Åsa B.

    2007-01-01

    Bnip3 is a pro-apoptotic member of the Bcl-2 family that is down-regulated in pancreatic cancers, which correlates with resistance to chemotherapy and a worsened prognosis. In contrast, Bnip3 is up-regulated in heart failure and contributes to loss of myocardial cells during I/R (ischaemia/reperfusion). Bnip3 exerts its action at the mitochondria, but the mechanism by which Bnip3 mediates mitochondrial dysfunction is not clear. In the present study, we have identified Bax and Bak as downstream effectors of Bnip3-mediated mitochondrial dysfunction. Bnip3 plays a role in hypoxia-mediated cell death, but MEFs (mouse embryonic fibroblasts) derived from mice deficient in Bax and Bak were completely resistant to hypoxia even with substantial up-regulation of Bnip3. These cells were also resistant to Bnip3 overexpression, but re-expression of Bax or Bak restored susceptibility to Bnip3, suggesting that Bnip3 can act via either Bax or Bak. In contrast, Bnip3 overexpression in wild-type MEFs induced mitochondrial dysfunction with loss of membrane potential and release of cytochrome c. Cell death by Bnip3 was reduced in the presence of mPTP (mitochondrial permeability transition pore) inhibitors, but did not prevent Bnip3-mediated activation of Bax or Bak. Moreover, overexpression of Bnip3ΔTM, a dominant-negative form of Bnip3, reduced translocation of GFP (green fluorescent protein)–Bax to mitochondria during sI/R (simulated I/R) in HL-1 myocytes. Similarly, down-regulation of Bnip3 using RNA interference decreased activation of Bax in response to sI/R in HL-1 myocytes. These results suggest that Bnip3 mediates mitochondrial dysfunction through activation of Bax or Bak which is independent of mPTP opening. PMID:17447897

  7. Role of inorganic polyphosphate in mammalian cells: from signal transduction and mitochondrial metabolism to cell death.

    PubMed

    Angelova, Plamena R; Baev, Artyom Y; Berezhnov, Alexey V; Abramov, Andrey Y

    2016-02-01

    Inorganic polyphosphate (polyP) is a polymer compromised of linearly arranged orthophosphate units that are linked through high-energy phosphoanhydride bonds. The chain length of this polymer varies from five to several thousand orthophosphates. PolyP is distributed in the most of the living organisms and plays multiple functions in mammalian cells, it is important for blood coagulation, cancer, calcium precipitation, immune response and many others. Essential role of polyP is shown for mitochondria, from implication into energy metabolism and mitochondrial calcium handling to activation of permeability transition pore (PTP) and cell death. PolyP is a gliotransmitter which transmits the signal in astrocytes via activation of P2Y1 receptors and stimulation of phospholipase C. PolyP-induced calcium signal in astrocytes can be stimulated by different lengths of this polymer but only long chain polyP induces mitochondrial depolarization by inhibition of respiration and opening of the PTP. It leads to induction of astrocytic cell death which can be prevented by inhibition of PTP with cyclosporine A. Thus, medium- and short-length polyP plays role in signal transduction and mitochondrial metabolism of astrocytes and long chain of this polymer can be toxic for the cells. PMID:26862186

  8. LIM kinase-2 induces programmed necrotic neuronal death via dysfunction of DRP1-mediated mitochondrial fission.

    PubMed

    Kim, J-E; Ryu, H J; Kim, M J; Kang, T-C

    2014-07-01

    Although the aberrant activation of cell cycle proteins has a critical role in neuronal death, effectors or mediators of cyclin D1/cyclin-dependent kinase 4 (CDK4)-mediated death signal are still unknown. Here, we describe a previously unsuspected role of LIM kinase 2 (LIMK2) in programmed necrotic neuronal death. Downregulation of p27(Kip1) expression by Rho kinase (ROCK) activation induced cyclin D1/CDK4 expression levels in neurons vulnerable to status epilepticus (SE). Cyclin D1/CDK4 complex subsequently increased LIMK2 expression independent of caspase-3 and receptor interacting protein kinase 1 activity. In turn, upregulated LIMK2 impaired dynamic-related protein-1 (DRP1)-mediated mitochondrial fission without alterations in cofilin phosphorylation/expression and finally resulted in necrotic neuronal death. Inhibition of LIMK2 expression and rescue of DRP1 function attenuated this programmed necrotic neuronal death induced by SE. Therefore, we suggest that the ROCK-p27(Kip1)-cyclin D1/CDK4-LIMK2-DRP1-mediated programmed necrosis may be new therapeutic targets for neuronal death.

  9. Therapeutic inhibition of mitochondrial function induces cell death in starvation-resistant renal cell carcinomas

    PubMed Central

    Isono, Takahiro; Chano, Tokuhiro; Yonese, Junji; Yuasa, Takeshi

    2016-01-01

    Renal cell carcinomas (RCC) have two types of cells for carbon metabolism and for cell signaling under nutrient-deprivation conditions, namely starvation-resistant and starvation-sensitive cells. Here, we evaluated the mitochondrial characteristics of these cell types and found that the resistant type possessed higher activities for both mitochondrial oxidative phosphorylation and glycolysis than the sensitive types. These higher activities were supported by the stored carbon, lipid and carbohydrate sources, and by a low level of mitochondrial reactive oxygen species (ROS) due to sustained SOD2 expression in the resistant RCC cells. In metastatic RCC cases, higher SOD2 expression was associated with a significantly shorter survival period. We found that treatment with the drugs etomoxir and buformin significantly reduced mitochondrial oxidative phosphorylation and induced cell death under glucose-deprivation conditions in starvation-resistant RCC cells. Our data suggest that inhibitory targeting of mitochondria might offer an effective therapeutic option for metastatic RCC that is resistant to current treatments. PMID:27157976

  10. Helicobacter pylori vacuolating cytotoxin A (VacA) engages the mitochondrial fission machinery to induce host cell death

    PubMed Central

    Jain, Prashant; Luo, Zhao-Qing; Blanke, Steven R.

    2011-01-01

    A number of pathogenic bacteria target mitochondria to modulate the host's apoptotic machinery. Studies here revealed that infection with the human gastric pathogen Helicobacter pylori disrupts the morphological dynamics of mitochondria as a mechanism to induce host cell death. The vacuolating cytotoxin A (VacA) is both essential and sufficient for inducing mitochondrial network fragmentation through the mitochondrial recruitment and activation of dynamin-related protein 1 (Drp1), which is a critical regulator of mitochondrial fission within cells. Inhibition of Drp1-induced mitochondrial fission within VacA-intoxicated cells inhibited the activation of the proapoptotic Bcl-2–associated X (Bax) protein, permeabilization of the mitochondrial outer membrane, and cell death. Our data reveal a heretofore unrecognized strategy by which a pathogenic microbe engages the host's apoptotic machinery. PMID:21903925

  11. Tumor cell death induced by the inhibition of mitochondrial electron transport: The effect of 3-hydroxybakuchiol

    SciTech Connect

    Jaña, Fabián; Faini, Francesca; Lapier, Michel; Pavani, Mario; Kemmerling, Ulrike; Morello, Antonio; Maya, Juan Diego; Jara, José; Parra, Eduardo; Ferreira, Jorge

    2013-10-15

    Changes in mitochondrial ATP synthesis can affect the function of tumor cells due to the dependence of the first step of glycolysis on mitochondrial ATP. The oxidative phosphorylation (OXPHOS) system is responsible for the synthesis of approximately 90% of the ATP in normal cells and up to 50% in most glycolytic cancers; therefore, inhibition of the electron transport chain (ETC) emerges as an attractive therapeutic target. We studied the effect of a lipophilic isoprenylated catechol, 3-hydroxybakuchiol (3-OHbk), a putative ETC inhibitor isolated from Psoralea glandulosa. 3-OHbk exerted cytotoxic and anti-proliferative effects on the TA3/Ha mouse mammary adenocarcinoma cell line and induced a decrease in the mitochondrial transmembrane potential, the activation of caspase-3, the opening of the mitochondrial permeability transport pore (MPTP) and nuclear DNA fragmentation. Additionally, 3-OHbk inhibited oxygen consumption, an effect that was completely reversed by succinate (an electron donor for Complex II) and duroquinol (electron donor for Complex III), suggesting that 3-OHbk disrupted the electron flow at the level of Complex I. The inhibition of OXPHOS did not increase the level of reactive oxygen species (ROS) but caused a large decrease in the intracellular ATP level. ETC inhibitors have been shown to induce cell death through necrosis and apoptosis by increasing ROS generation. Nevertheless, we demonstrated that 3-OHbk inhibited the ETC and induced apoptosis through an interaction with Complex I. By delivering electrons directly to Complex III with duroquinol, cell death was almost completely abrogated. These results suggest that 3-OHbk has antitumor activity resulting from interactions with the ETC, a system that is already deficient in cancer cells. - Highlights: • We studied the anticancer activity of a natural compound, 3-OHbk, on TA3/Ha cells. • 3-OHbk inhibited mitochondrial electron flow by interacting with Complex I. • Complex I inhibition did

  12. Lipid analogues as potential drugs for the regulation of mitochondrial cell death

    PubMed Central

    Murray, Michael; Dyari, Herryawan Ryadi Eziwar; Allison, Sarah E; Rawling, Tristan

    2014-01-01

    The mitochondrion plays an important role in the production of energy as ATP, the regulation of cell viability and apoptosis, and the biosynthesis of major structural and regulatory molecules, such as lipids. During ATP production, reactive oxygen species are generated that alter the intracellular redox state and activate apoptosis. Mitochondrial dysfunction is a well-recognized component of the pathogenesis of diseases such as cancer. Understanding mitochondrial function, and how this is dysregulated in disease, offers the opportunity for the development of drug molecules to specifically target such defects. Altered energy metabolism in cancer, in which ATP production occurs largely by glycolysis, rather than by oxidative phosphorylation, is attributable in part to the up-regulation of cell survival signalling cascades. These pathways also regulate the balance between pro-and anti-apoptotic factors that may determine the rate of cell death and proliferation. A number of anti-cancer drugs have been developed that target these factors and one of the most promising groups of agents in this regard are the lipid-based molecules that act directly or indirectly at the mitochondrion. These molecules have emerged in part from an understanding of the mitochondrial actions of naturally occurring fatty acids. Some of these agents have already entered clinical trials because they specifically target known mitochondrial defects in the cancer cell. LINKED ARTICLES This article is part of a themed issue on Mitochondrial Pharmacology: Energy, Injury & Beyond. To view the other articles in this issue visit http://dx.doi.org/10.1111/bph.2014.171.issue-8 PMID:24111728

  13. Colistin-Induced Nephrotoxicity in Mice Involves the Mitochondrial, Death Receptor, and Endoplasmic Reticulum Pathways

    PubMed Central

    Dai, Chongshan; Li, Jichang; Tang, Shusheng

    2014-01-01

    Nephrotoxicity is the dose-limiting factor for colistin, but the exact mechanism is unknown. This study aimed to investigate the roles of the mitochondrial, death receptor, and endoplasmic reticulum pathways in colistin-induced nephrotoxicity. Mice were intravenously administered 7.5 or 15 mg of colistin/kg of body weight/day (via a 3-min infusion and divided into two doses) for 7 days. Renal function, oxidative stress, and apoptosis were measured. Representative biomarkers involved in the mitochondrial, death receptor, and endoplasmic reticulum pathways were investigated, and the key markers involved in apoptosis and autophagy were examined. After 7-day colistin treatment, significant increase was observed with blood urea nitrogen, serum creatinine, and malondialdehyde, while activities of superoxide dismutase (SOD) and catalase decreased in the kidneys. Acute tubular necrosis and mitochondrial dysfunction were detected, and colistin-induced apoptosis was characterized by DNA fragmentation, cleavage of poly(ADP-ribose) polymerase (PARP-1), increase of 8-hydroxydeoxyguanosine (8-OHdG), and activation of caspases (caspase-8, -9, and -3). It was evident that colistin-induced apoptosis involved the mitochondrial pathway (downregulation of Bcl-2 and upregulation of cytochrome C [cytC] and Bax), death receptor pathway (upregulation of Fas, FasL, and Fas-associated death domain [FADD]), and endoplasmic reticulum pathway (upregulation of Grp78/Bip, ATF6, GADD153/CHOP, and caspase-12). In the 15-mg/kg/day colistin group, expression of the cyclin-dependent kinase 2 (CDK2) and phosphorylated JNK (p-JNK) significantly increased (P < 0.05), while in the 7.5-mg/kg/day colistin group, a large number of autophagolysosomes and classic autophagy were observed. Western blot results of Beclin-1 and LC3B indicated that autophagy may play a protective role in colistin-induced nephrotoxicity. In conclusion, this is the first study to demonstrate that all three major apoptosis pathways

  14. Beta-nodavirus B2 protein induces hydrogen peroxide production, leading to Drp1-recruited mitochondrial fragmentation and cell death via mitochondrial targeting.

    PubMed

    Su, Yu C; Chiu, Hsuan W; Hung, Jo C; Hong, Jiann R

    2014-10-01

    Because the role of the viral B2 protein in the pathogenesis of nervous necrosis virus infection remains unknown, the aim of the present study was to determine the effects of B2 protein on hydrogen peroxide (H2O2)-mediated cell death via mitochondrial targeting. Using a B2 deletion mutant, the B2 mitochondrial targeting signal sequence ((41)RTFVISAHAA(50)) correlated with mitochondrial free radical production and cell death in fish cells, embryonic zebrafish, and human cancer cells. After treatment of grouper fin cells (GF-1) overexpressing B2 protein with the anti-oxidant drug, N-acetylcysteine (NAC), and overexpression of the antioxidant enzymes, zfCu/Zn superoxide dismutase (SOD) and zfCatalase, decreased H2O2 production and cell death were observed. To investigate the correlation between B2 cytotoxicity and H2O2 production in vivo, B2 was injected into zebrafish embryos. Cell damage, as assessed by the acridine orange assay, gradually increased over 24 h post-fertilization, and was accompanied by marked increases in H2O2 production and embryonic death. Increased oxidative stress, as evidenced by the up-regulation of Mn SOD, catalase, and Nrf2, was also observed during this period. Finally, B2-induced dynamin-related protein 1 (Drp1)-mediated mitochondrial fragmentation and cell death could be reversed by NAC and inhibitors of Drp1 and Mdivi in GF-1 cells. Taken together, betanodavirus B2 induces H2O2 production via targeting the mitochondria, where it inhibits complex II function. H2O2 activates Drp1, resulting in its association with the mitochondria, mitochondrial fission and cell death in vitro and in vivo.

  15. Beta-nodavirus B2 protein induces hydrogen peroxide production, leading to Drp1-recruited mitochondrial fragmentation and cell death via mitochondrial targeting.

    PubMed

    Su, Yu C; Chiu, Hsuan W; Hung, Jo C; Hong, Jiann R

    2014-10-01

    Because the role of the viral B2 protein in the pathogenesis of nervous necrosis virus infection remains unknown, the aim of the present study was to determine the effects of B2 protein on hydrogen peroxide (H2O2)-mediated cell death via mitochondrial targeting. Using a B2 deletion mutant, the B2 mitochondrial targeting signal sequence ((41)RTFVISAHAA(50)) correlated with mitochondrial free radical production and cell death in fish cells, embryonic zebrafish, and human cancer cells. After treatment of grouper fin cells (GF-1) overexpressing B2 protein with the anti-oxidant drug, N-acetylcysteine (NAC), and overexpression of the antioxidant enzymes, zfCu/Zn superoxide dismutase (SOD) and zfCatalase, decreased H2O2 production and cell death were observed. To investigate the correlation between B2 cytotoxicity and H2O2 production in vivo, B2 was injected into zebrafish embryos. Cell damage, as assessed by the acridine orange assay, gradually increased over 24 h post-fertilization, and was accompanied by marked increases in H2O2 production and embryonic death. Increased oxidative stress, as evidenced by the up-regulation of Mn SOD, catalase, and Nrf2, was also observed during this period. Finally, B2-induced dynamin-related protein 1 (Drp1)-mediated mitochondrial fragmentation and cell death could be reversed by NAC and inhibitors of Drp1 and Mdivi in GF-1 cells. Taken together, betanodavirus B2 induces H2O2 production via targeting the mitochondria, where it inhibits complex II function. H2O2 activates Drp1, resulting in its association with the mitochondria, mitochondrial fission and cell death in vitro and in vivo. PMID:25008790

  16. Metabolic autopsy with postmortem cultured fibroblasts in sudden unexpected death in infancy: diagnosis of mitochondrial respiratory chain disorders.

    PubMed

    Yamamoto, Takuma; Emoto, Yuko; Murayama, Kei; Tanaka, Hidekazu; Kuriu, Yukiko; Ohtake, Akira; Matoba, Ryoji

    2012-08-01

    Mitochondrial respiratory chain disorders are the most common disorders among inherited metabolic disorders. However, there are few published reports regarding the relationship between mitochondrial respiratory chain disorders and sudden unexpected death in infancy. In the present study, we performed metabolic autopsy in 13 Japanese cases of sudden unexpected death in infancy. We performed fat staining of liver and postmortem acylcarnitine analysis. In addition, we analyzed mitochondrial respiratory chain enzyme activity in frozen organs as well as in postmortem cultured fibroblasts. In heart, 11 cases of complex I activity met the major criteria and one case of complex I activity met the minor criteria. In liver, three cases of complex I activity met the major criteria and four cases of complex I activity met the minor criteria. However, these specimens are susceptible to postmortem changes and, therefore, correct enzyme analysis is hard to be performed. In cultured fibroblasts, only one case of complex I activity met the major criteria and one case of complex I activity met the minor criteria. Cultured fibroblasts are not affected by postmortem changes and, therefore, reflect premortem information more accurately. These cases might not have been identified without postmortem cultured fibroblasts. In conclusion, we detected one probable case and one possible case of mitochondrial respiratory chain disorders among 13 Japanese cases of sudden unexpected death in infancy. Mitochondrial respiratory chain disorders are one of the important inherited metabolic disorders causing sudden unexpected death in infancy. We advocate metabolic autopsy with postmortem cultured fibroblasts in sudden unexpected death in infancy cases.

  17. Calpastatin overexpression reduces oxidative stress-induced mitochondrial impairment and cell death in human neuroblastoma SH-SY5Y cells by decreasing calpain and calcineurin activation, induction of mitochondrial fission and destruction of mitochondrial fusion.

    PubMed

    Tangmansakulchai, Kulvadee; Abubakar, Zuroida; Kitiyanant, Narisorn; Suwanjang, Wilasinee; Leepiyasakulchai, Chaniya; Govitrapong, Piyarat; Chetsawang, Banthit

    2016-09-01

    Calpain is an intracellular Ca(2+)-dependent protease, and the activation of calpain has been implicated in neurodegenerative diseases. Calpain activity can be regulated by calpastatin, an endogenous specific calpain inhibitor. Several lines of evidence have demonstrated a potential role of calpastatin in preventing calpain-mediated pathogenesis. Additionally, several studies have revealed that calpain activation and mitochondrial damage are involved in the cell death process; however, recent evidence has not clearly indicated a neuroprotective mechanism of calpastatin against calpain-dependent mitochondrial impairment in the process of neuronal cell death. Therefore, the purpose of this study was to investigate the potential ability of calpastatin to inhibit calpain activation and mitochondrial impairment in oxidative stress-induced neuron degeneration. Calpastatin was stably overexpressed in human neuroblastoma SH-SY5Y cells. In non-calpastatin overexpressing SH-SY5Y cells, hydrogen peroxide significantly decreased cell viability, superoxide dismutase activity, mitochondrial membrane potential, ATP production and mitochondrial fusion protein (Opa1) levels in the mitochondrial fraction but increased reactive oxygen species formation, calpain and calcineurin activation, mitochondrial fission protein (Fis1 and Drp1) levels in the mitochondrial fraction and apoptotic cells. Nevertheless, these toxic effects were abolished in hydrogen peroxide-treated calpastatin-overexpressing SH-SY5Y cells. The results of the present study demonstrate the potential ability of calpastatin to diminish calpain and calcineurin activation and mitochondrial impairment in neurons that are affected by oxidative damage. PMID:27453331

  18. Isoniazid-induced cell death is precipitated by underlying mitochondrial complex I dysfunction in mouse hepatocytes.

    PubMed

    Lee, Kang Kwang; Fujimoto, Kazunori; Zhang, Carmen; Schwall, Christine T; Alder, Nathan N; Pinkert, Carl A; Krueger, Winfried; Rasmussen, Theodore; Boelsterli, Urs A

    2013-12-01

    Isoniazid (INH) is an antituberculosis drug that has been associated with idiosyncratic liver injury in susceptible patients. The underlying mechanisms are still unclear, but there is growing evidence that INH and/or its major metabolite, hydrazine, may interfere with mitochondrial function. However, hepatic mitochondria have a large reserve capacity, and minor disruption of energy homeostasis does not necessarily induce cell death. We explored whether pharmacologic or genetic impairment of mitochondrial complex I may amplify mitochondrial dysfunction and precipitate INH-induced hepatocellular injury. We found that INH (≤ 3000 μM) did not induce cell injury in cultured mouse hepatocytes, although it decreased hepatocellular respiration and ATP levels in a concentration-dependent fashion. However, coexposure of hepatocytes to INH and nontoxic concentrations of the complex I inhibitors rotenone (3 μM) or piericidin A (30 nM) resulted in massive ATP depletion and cell death. Although both rotenone and piericidin A increased MitoSox-reactive fluorescence, Mito-TEMPO or N-acetylcysteine did not attenuate the extent of cytotoxicity. However, preincubation of cells with the acylamidase inhibitor bis-p-nitrophenol phosphate provided protection from hepatocyte injury induced by rotenone/INH (but not rotenone/hydrazine), suggesting that hydrazine was the cell-damaging species. Indeed, we found that hydrazine directly inhibited the activity of solubilized complex II. Hepatocytes isolated from mutant Ndufs4(+/-) mice, although featuring moderately lower protein expression levels of this complex I subunit in liver mitochondria, exhibited unchanged hepatic complex I activity and were therefore not sensitized to INH. These data indicate that underlying inhibition of complex I, which alone is not acutely toxic, can trigger INH-induced hepatocellular injury.

  19. BMAP-28, an Antibiotic Peptide of Innate Immunity, Induces Cell Death through Opening of the Mitochondrial Permeability Transition Pore

    PubMed Central

    Risso, Angela; Braidot, Enrico; Sordano, Maria Concetta; Vianello, Angelo; Macrì, Francesco; Skerlavaj, Barbara; Zanetti, Margherita; Gennaro, Renato; Bernardi, Paolo

    2002-01-01

    BMAP-28, a bovine antimicrobial peptide of the cathelicidin family, induces membrane permeabilization and death in human tumor cell lines and in activated, but not resting, human lymphocytes. In addition, we found that BMAP-28 causes depolarization of the inner mitochondrial membrane in single cells and in isolated mitochondria. The effect of the peptide was synergistic with that of Ca2+ and inhibited by cyclosporine, suggesting that depolarization depends on opening of the mitochondrial permeability transition pore. The occurrence of a permeability transition was investigated on the basis of mitochondrial permeabilization to calcein and cytochrome c release. We show that BMAP-28 permeabilizes mitochondria to entrapped calcein in a cyclosporine-sensitive manner and that it releases cytochrome c in situ. Our results demonstrate that BMAP-28 is an inducer of the mitochondrial permeability transition pore and that its cytotoxic potential depends on its effects on mitochondrial permeability. PMID:11865069

  20. Inhibition of HIF-prolyl-4-hydroxylases prevents mitochondrial impairment and cell death in a model of neuronal oxytosis

    PubMed Central

    Neitemeier, S; Dolga, A M; Honrath, B; Karuppagounder, S S; Alim, I; Ratan, R R; Culmsee, C

    2016-01-01

    Mitochondrial impairment induced by oxidative stress is a main characteristic of intrinsic cell death pathways in neurons underlying the pathology of neurodegenerative diseases. Therefore, protection of mitochondrial integrity and function is emerging as a promising strategy to prevent neuronal damage. Here, we show that pharmacological inhibition of hypoxia-inducible factor prolyl-4-hydroxylases (HIF-PHDs) by adaptaquin inhibits lipid peroxidation and fully maintains mitochondrial function as indicated by restored mitochondrial membrane potential and ATP production, reduced formation of mitochondrial reactive oxygen species (ROS) and preserved mitochondrial respiration, thereby protecting neuronal HT-22 cells in a model of glutamate-induced oxytosis. Selective reduction of PHD1 protein using CRISPR/Cas9 technology also reduced both lipid peroxidation and mitochondrial impairment, and attenuated glutamate toxicity in the HT-22 cells. Regulation of activating transcription factor 4 (ATF4) expression levels and related target genes may mediate these beneficial effects. Overall, these results expose HIF-PHDs as promising targets to protect mitochondria and, thereby, neurons from oxidative cell death. PMID:27148687

  1. A Two-Step Mechanism for Cell Fate Decision by Coordination of Nuclear and Mitochondrial p53 Activities

    PubMed Central

    Tian, Xiao-Jun; Liu, Feng; Zhang, Xiao-Peng; Li, Jun; Wang, Wei

    2012-01-01

    The tumor suppressor p53 has a crucial role in the DNA damage response. Here, we proposed an integrated model of the p53 network and explored how the nuclear and mitochondrial p53 pathways are coordinated to determine cell fates after -irradiation in radiosensitive tissues. Using numerical simulations, we found that depending on the extent of DNA damage, cells may survive, commit apoptosis after cell cycle arrest, or undergo apoptosis soon after irradiation. There exists a large cell-to-cell variability in outcome because of stochasticity in the generation and repair of DNA damage as well as cellular heterogeneity. At the cell population level, there occur two waves of apoptosis: a fast wave mediated by mitochondrial p53 within three hours postirradiation, and a slow wave mediated by nuclear p53 after eight hours postirradiation. Thus, we propose a two-step mechanism for cell fate decision. The first step is to decide whether DNA damage is severe enough to trigger apoptosis directly through the mitochondrial p53 pathway, while the second step is to determine whether the damage is fixed after cell cycle arrest. Such a mechanism may represent an efficient and reliable control mode, avoiding unnecessary death or greatly promoting the execution of apoptosis. It was also demonstrated that nuclear p53 can inhibit the pro-apoptotic activity of mitochondrial p53 by transactivating p21, and Mdm2 can facilitate apoptosis by promoting the mono-ubiquitination of p53. These results are either in good agreement with experimental observations or experimentally testable. Our work suggests that both the transcription-independent and -dependent p53 activities are indispensable for a reliable choice of cell fate and also provides clues to therapeutic manipulation of the p53 pathway in cancer treatment. PMID:22679490

  2. Rotenone induces cell death in primary dopaminergic culture by increasing ROS production and inhibiting mitochondrial respiration.

    PubMed

    Radad, Khaled; Rausch, Wolf-Dieter; Gille, Gabriele

    2006-09-01

    Although the definite etiology of Parkinson's disease is still unclear, increasing evidence has suggested an important role for environmental factors such as exposure to pesticides in increasing the risk of developing Parkinson's disease. In the present study, primary cultures prepared from embryonic mouse mesencephala were applied to investigate the toxic effects and underlying mechanisms of rotenone-induced neuronal cell death relevant to Parkinson's disease. Results revealed that rotenone destroyed dopaminergic neurons in a dose- and time-dependent manner. Consistent with the cytotoxic effect of rotenone as evidenced by dopaminergic cell loss, it significantly increased the release of lactate dehydrogenase into the culture medium, the number of necrotic cells in the culture and the number of nuclei showing apoptotic features. Rotenone exerted toxicity by decreasing the mitochondrial membrane potential, increasing reactive oxygen species production and shifting respiration to a more anaerobic state.

  3. Cell death and survival through the endoplasmic reticulum-mitochondrial axis.

    PubMed

    Bravo-Sagua, R; Rodriguez, A E; Kuzmicic, J; Gutierrez, T; Lopez-Crisosto, C; Quiroga, C; Díaz-Elizondo, J; Chiong, M; Gillette, T G; Rothermel, B A; Lavandero, S

    2013-02-01

    The endoplasmic reticulum has a central role in biosynthesis of a variety of proteins and lipids. Mitochondria generate ATP, synthesize and process numerous metabolites, and are key regulators of cell death. The architectures of endoplasmic reticulum and mitochondria change continually via the process of membrane fusion, fission, elongation, degradation, and renewal. These structural changes correlate with important changes in organellar function. Both organelles are capable of moving along the cytoskeleton, thus changing their cellular distribution. Numerous studies have demonstrated coordination and communication between mitochondria and endoplasmic reticulum. A focal point for these interactions is a zone of close contact between them known as the mitochondrial-associated endoplasmic reticulum membrane (MAM), which serves as a signaling juncture that facilitates calcium and lipid transfer between organelles. Here we review the emerging data on how communication between endoplasmic reticulum and mitochondria can modulate organelle function and determine cellular fate.

  4. Cell death and survival through the endoplasmic reticulum-mitochondrial axis.

    PubMed

    Bravo-Sagua, R; Rodriguez, A E; Kuzmicic, J; Gutierrez, T; Lopez-Crisosto, C; Quiroga, C; Díaz-Elizondo, J; Chiong, M; Gillette, T G; Rothermel, B A; Lavandero, S

    2013-02-01

    The endoplasmic reticulum has a central role in biosynthesis of a variety of proteins and lipids. Mitochondria generate ATP, synthesize and process numerous metabolites, and are key regulators of cell death. The architectures of endoplasmic reticulum and mitochondria change continually via the process of membrane fusion, fission, elongation, degradation, and renewal. These structural changes correlate with important changes in organellar function. Both organelles are capable of moving along the cytoskeleton, thus changing their cellular distribution. Numerous studies have demonstrated coordination and communication between mitochondria and endoplasmic reticulum. A focal point for these interactions is a zone of close contact between them known as the mitochondrial-associated endoplasmic reticulum membrane (MAM), which serves as a signaling juncture that facilitates calcium and lipid transfer between organelles. Here we review the emerging data on how communication between endoplasmic reticulum and mitochondria can modulate organelle function and determine cellular fate. PMID:23228132

  5. Oleuropein Prevents Neuronal Death, Mitigates Mitochondrial Superoxide Production and Modulates Autophagy in a Dopaminergic Cellular Model

    PubMed Central

    Achour, Imène; Arel-Dubeau, Anne-Marie; Renaud, Justine; Legrand, Manon; Attard, Everaldo; Germain, Marc; Martinoli, Maria-Grazia

    2016-01-01

    Parkinson’s disease (PD) is a progressive neurodegenerative disorder, primarily affecting dopaminergic neurons in the substantia nigra. There is currently no cure for PD and present medications aim to alleviate clinical symptoms, thus prevention remains the ideal strategy to reduce the prevalence of this disease. The goal of this study was to investigate whether oleuropein (OLE), the major phenolic compound in olive derivatives, may prevent neuronal degeneration in a cellular dopaminergic model of PD, differentiated PC12 cells exposed to the potent parkinsonian toxin 6-hydroxydopamine (6-OHDA). We also investigated OLE’s ability to mitigate mitochondrial oxidative stress and modulate the autophagic flux. Our results obtained by measuring cytotoxicity and apoptotic events demonstrate that OLE significantly decreases neuronal death. OLE could also reduce mitochondrial production of reactive oxygen species resulting from blocking superoxide dismutase activity. Moreover, quantification of autophagic and acidic vesicles in the cytoplasm alongside expression of specific autophagic markers uncovered a regulatory role for OLE against autophagic flux impairment induced by bafilomycin A1. Altogether, our results define OLE as a neuroprotective, anti-oxidative and autophagy-regulating molecule, in a neuronal dopaminergic cellular model. PMID:27517912

  6. Oleuropein Prevents Neuronal Death, Mitigates Mitochondrial Superoxide Production and Modulates Autophagy in a Dopaminergic Cellular Model.

    PubMed

    Achour, Imène; Arel-Dubeau, Anne-Marie; Renaud, Justine; Legrand, Manon; Attard, Everaldo; Germain, Marc; Martinoli, Maria-Grazia

    2016-01-01

    Parkinson's disease (PD) is a progressive neurodegenerative disorder, primarily affecting dopaminergic neurons in the substantia nigra. There is currently no cure for PD and present medications aim to alleviate clinical symptoms, thus prevention remains the ideal strategy to reduce the prevalence of this disease. The goal of this study was to investigate whether oleuropein (OLE), the major phenolic compound in olive derivatives, may prevent neuronal degeneration in a cellular dopaminergic model of PD, differentiated PC12 cells exposed to the potent parkinsonian toxin 6-hydroxydopamine (6-OHDA). We also investigated OLE's ability to mitigate mitochondrial oxidative stress and modulate the autophagic flux. Our results obtained by measuring cytotoxicity and apoptotic events demonstrate that OLE significantly decreases neuronal death. OLE could also reduce mitochondrial production of reactive oxygen species resulting from blocking superoxide dismutase activity. Moreover, quantification of autophagic and acidic vesicles in the cytoplasm alongside expression of specific autophagic markers uncovered a regulatory role for OLE against autophagic flux impairment induced by bafilomycin A1. Altogether, our results define OLE as a neuroprotective, anti-oxidative and autophagy-regulating molecule, in a neuronal dopaminergic cellular model. PMID:27517912

  7. Methylglyoxal induces cell death through endoplasmic reticulum stress-associated ROS production and mitochondrial dysfunction.

    PubMed

    Chan, Chi-Ming; Huang, Duen-Yi; Huang, Yi-Pin; Hsu, Shu-Hao; Kang, Lan-Ya; Shen, Chung-Min; Lin, Wan-Wan

    2016-09-01

    Diabetic retinopathy (DR) and age-related macular degeneration (AMD) are two important leading causes of acquired blindness in developed countries. As accumulation of advanced glycation end products (AGEs) in retinal pigment epithelial (RPE) cells plays an important role in both DR and AMD, and the methylglyoxal (MGO) within the AGEs exerts irreversible effects on protein structure and function, it is crucial to understand the underlying mechanism of MGO-induced RPE cell death. Using ARPE-19 as the cell model, this study revealed that MGO induces RPE cell death through a caspase-independent manner, which relying on reactive oxygen species (ROS) formation, mitochondrial membrane potential (MMP) loss, intracellular calcium elevation and endoplasmic reticulum (ER) stress response. Suppression of ROS generation can reverse the MGO-induced ROS production, MMP loss, intracellular calcium increase and cell death. Moreover, store-operated calcium channel inhibitors MRS1845 and YM-58483, but not the inositol 1,4,5-trisphosphate (IP3) receptor inhibitor xestospongin C, can block MGO-induced ROS production, MMP loss and sustained intracellular calcium increase in ARPE-19 cells. Lastly, inhibition of ER stress by salubrinal and 4-PBA can reduce the MGO-induced intracellular events and cell death. Therefore, our data indicate that MGO can decrease RPE cell viability, resulting from the ER stress-dependent intracellular ROS production, MMP loss and increased intracellular calcium increase. As MGO is one of the components of drusen in AMD and is the AGEs adduct in DR, this study could provide a valuable insight into the molecular pathogenesis and therapeutic intervention of AMD and DR. PMID:27307396

  8. Mitochondrial Dysfunction Induced by Nuclear Poly(ADP-Ribose) Polymerase-1: a Treatable Cause of Cell Death in Stroke

    PubMed Central

    Baxter, Paul; Chen, Yanting; Xu, Yun; Swanson, Raymond A.

    2014-01-01

    Many drugs targeting excitotoxic cell death have demonstrated robust neuroprotective effects in animal models of cerebral ischemia. However, these neuroprotective effects have almost universally required drug administration at relatively short time intervals after ischemia onset. This finding has translated to clinical trial results; interventions targeting excitotoxicity have had no demonstrable efficacy when initiated hours after ischemia onset, but beneficial effects have been reported with more rapid initiation. Consequently, there continues to be a need for interventions with efficacy at later time points after ischemia. Here, we focus on mitochondrial dysfunction as both a relatively late event in ischemic neuronal death and a recognized cause of delayed neuronal death. Activation of poly(ADP-ribose) polymerase-1 (PARP-1) is a primary cause of mitochondrial depolarization and subsequent mitochondria-triggered cell death in ischemia reperfusion. PARP-1 consumes cytosolic NAD+, thereby blocking both glycolytic ATP production and delivery of glucose carbon to mitochondria for oxidative metabolism. However, ketone bodies such as pyruvate, beta- and gamma-hydroxybutyrate, and 1,4-butanediol can fuel mitochondrial metabolism in cells with depleted cytosolic NAD+ as long as the mitochondria remain functional. Ketone bodies have repeatedly been shown to be highly effective in preventing cell death in animal models of ischemia, but a rigorous study of the time window of opportunity for this approach remains to be performed. PMID:24323707

  9. Sequential reduction of mitochondrial transmembrane potential and generation of reactive oxygen species in early programmed cell death

    PubMed Central

    1995-01-01

    Programmed cell death (PCD) is a physiological process commonly defined by alterations in nuclear morphology (apoptosis) and/or characteristic stepwise degradation of chromosomal DNA occurring before cytolysis. However, determined characteristics of PCD such as loss in mitochondrial reductase activity or cytolysis can be induced in enucleated cells, indicating cytoplasmic PCD control. Here we report a sequential disregulation of mitochondrial function that precedes cell shrinkage and nuclear fragmentation. A first cyclosporin A-inhibitable step of ongoing PCD is characterized by a reduction of mitochondrial transmembrane potential, as determined by specific fluorochromes (5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolcarbocyanine++ + iodide; 3,3'dihexyloxacarbocyanine iodide). Cytofluorometrically purified cells with reduced mitochondrial transmembrane potential are initially incapable of oxidizing hydroethidine (HE) into ethidium. Upon short-term in vitro culture, such cells acquire the capacity of HE oxidation, thus revealing a second step of PCD marked by mitochondrial generation of reactive oxygen species (ROS). This step can be selectively inhibited by rotenone and ruthenium red yet is not affected by cyclosporin A. Finally, cells reduce their volume, a step that is delayed by radical scavengers, indicating the implication of ROS in the apoptotic process. This sequence of alterations accompanying early PCD is found in very different models of apoptosis induction: glucocorticoid-induced death of lymphocytes, activation-induced PCD of T cell hybridomas, and tumor necrosis factor-induced death of U937 cells. Transfection with the antiapoptotic protooncogene Bcl-2 simultaneously inhibits mitochondrial alterations and apoptotic cell death triggered by steroids or ceramide. In vivo injection of fluorochromes such as 5,5',6,6'-tetrachloro-1,1',3,3'- tetraethylbenzimidazolcarbocyanine iodide; 3,3'dihexyloxacarbocyanine iodide; or HE allows for the detection of

  10. Mechanisms of cell death pathway activation following drug-induced inhibition of mitochondrial complex I

    PubMed Central

    Imaizumi, Naoki; Kwang Lee, Kang; Zhang, Carmen; Boelsterli, Urs A.

    2015-01-01

    Respiratory complex I inhibition by drugs and other chemicals has been implicated as a frequent mode of mitochondria-mediated cell injury. However, the exact mechanisms leading to the activation of cell death pathways are incompletely understood. This study was designed to explore the relative contributions to cell injury of three distinct consequences of complex I inhibition, i.e., impairment of ATP biosynthesis, increased formation of superoxide and, hence, peroxynitrite, and inhibition of the mitochondrial protein deacetylase, Sirt3, due to imbalance of the NADH/NAD+ ratio. We used the antiviral drug efavirenz (EFV) to model drug-induced complex I inhibition. Exposure of cultured mouse hepatocytes to EFV resulted in a rapid onset of cell injury, featuring a no-effect level at 30 µM EFV and submaximal effects at 50 µM EFV. EFV caused a concentration-dependent decrease in cellular ATP levels. Furthermore, EFV resulted in increased formation of peroxynitrite and oxidation of mitochondrial protein thiols, including cyclophilin D (CypD). This was prevented by the superoxide scavenger, Fe-TCP, or the peroxynitrite decomposition catalyst, Fe-TMPyP. Both ferroporphyrins completely protected from EFV-induced cell injury, suggesting that peroxynitrite contributed to the cell injury. Finally, EFV increased the NADH/NAD+ ratio, inhibited Sirt3 activity, and led to hyperacetylated lysine residues, including those in CypD. However, hepatocytes isolated from Sirt3-null mice were protected against 40 µM EFV as compared to their wild-type controls. In conclusion, these data are compatible with the concept that chemical inhibition of complex I activates multiple pathways leading to cell injury; among these, peroxynitrite formation may be the most critical. PMID:25625582

  11. Death--whose decision? Euthanasia and the terminally ill.

    PubMed

    Fraser, S I; Walters, J W

    2000-04-01

    In Australia and Oregon, USA, legislation to permit statutory sanctioned physician-assisted dying was enacted. However, opponents, many of whom held strong religious views, were successful with repeal in Australia. Similar opposition in Oregon was formidable, but ultimately lost in a 60-40% vote reaffirming physician-assisted dying. This paper examines the human dilemma which arises when technological advances in end-of-life medicine conflict with traditional and religious sanctity-of-life values. Society places high value on personal autonomy, particularly in the United States. We compare the potential for inherent contradictions and arbitrary decisions where patient autonomy is either permitted or forbidden. The broader implications for human experience resulting from new legislation in both Australia and Oregon are discussed. We conclude that allowing autonomy for the terminally ill, within circumscribed options, results in fewer ethical contradictions and greater preservation of dignity. PMID:10786323

  12. It's only a matter of time: death, legacies, and intergenerational decisions.

    PubMed

    Wade-Benzoni, Kimberly A; Tost, Leigh Plunkett; Hernandez, Morela; Larrick, Richard P

    2012-07-01

    Intergenerational decisions affect other people in the future. The combination of intertemporal and interpersonal distance between decision makers in the present and other people in the future may lead one to expect little intergenerational generosity. In the experiments reported here, however, we posited that the negative effect of intertemporal distance on intergenerational beneficence would be reversed when people were primed with thoughts of death. This reversal would occur because death priming leads individuals to be concerned with having a lasting impact on other people in the future. Our experiments show that when individuals are exposed to death priming, the expected tendency to allocate fewer resources to others in the future, as compared with others in the present, is reversed. Our findings suggest that legacy motivations triggered by death priming can trump intergenerational discounting tendencies and promote intergenerational beneficence.

  13. It's only a matter of time: death, legacies, and intergenerational decisions.

    PubMed

    Wade-Benzoni, Kimberly A; Tost, Leigh Plunkett; Hernandez, Morela; Larrick, Richard P

    2012-07-01

    Intergenerational decisions affect other people in the future. The combination of intertemporal and interpersonal distance between decision makers in the present and other people in the future may lead one to expect little intergenerational generosity. In the experiments reported here, however, we posited that the negative effect of intertemporal distance on intergenerational beneficence would be reversed when people were primed with thoughts of death. This reversal would occur because death priming leads individuals to be concerned with having a lasting impact on other people in the future. Our experiments show that when individuals are exposed to death priming, the expected tendency to allocate fewer resources to others in the future, as compared with others in the present, is reversed. Our findings suggest that legacy motivations triggered by death priming can trump intergenerational discounting tendencies and promote intergenerational beneficence. PMID:22692338

  14. Mitochondrial calcium uniporter silencing potentiates caspase-independent cell death in MDA-MB-231 breast cancer cells.

    PubMed

    Curry, Merril C; Peters, Amelia A; Kenny, Paraic A; Roberts-Thomson, Sarah J; Monteith, Gregory R

    2013-05-10

    The mitochondrial calcium uniporter (MCU) transports free ionic Ca(2+) into the mitochondrial matrix. We assessed MCU expression in clinical breast cancer samples using microarray analysis and the consequences of MCU silencing in a breast cancer cell line. Our results indicate that estrogen receptor negative and basal-like breast cancers are characterized by elevated levels of MCU. Silencing of MCU expression in the basal-like MDA-MB-231 breast cancer cell line produced no change in proliferation or cell viability. However, distinct consequences of MCU silencing were seen on cell death pathways. Caspase-dependent cell death initiated by the Bcl-2 inhibitor ABT-263 was not altered by MCU silencing; whereas caspase-independent cell death induced by the calcium ionophore ionomycin was potentiated by MCU silencing. Measurement of cytosolic Ca(2+) levels showed that the promotion of ionomycin-induced cell death by MCU silencing occurs independently of changes in bulk cytosolic Ca(2+) levels. This study demonstrates that MCU overexpression is a feature of some breast cancers and that MCU overexpression may offer a survival advantage against some cell death pathways. MCU inhibitors may be a strategy to increase the effectiveness of therapies that act through the induction of caspase-independent cell death pathways in estrogen receptor negative and basal-like breast cancers.

  15. Iminophosphorane-organogold(III) complexes induce cell death through mitochondrial ROS production

    PubMed Central

    Vela, Laura; Contel, María; Palomera, Luis; Azaceta, Gemma; Marzo, Isabel

    2011-01-01

    Gold compounds are being investigated as potential antitumor drugs. Some gold(III) derivatives have shown to induce cell death in solid tumors but their mechanism of action differs from that of cisplatin, since most of these compounds do not bind to DNA. We have explored cellular events triggered by three different iminophosphorane-organo gold(III) compounds in leukemia cells (a neutral compound with two chloride ligands [Au{κ2-C,N-C6H4(PPh2=N(C6H5)-2}Cl2] 1, and two cationic compounds with either a dithiocarbamate ligand [Au{κ2-C,N-C6H4(PPh2=N(C6H5)-2}(S2CN-Me2)]PF6 2, or a water-soluble phosphine and a chloride ligand [Au{κ2-C,N-C6H4(PPh2=N(C6H5)-2}(P{Cp(m-C6H4-SO3Na)2}3) Cl]PF6 3). All three compounds showed higher toxicity against leukemia cells when compared to normal T-lymphocytes. Compounds 1 and 2 induced both necrosis and apoptosis, while 3 was mainly apoptotic. Necrotic cell death induced by 1 and 2 was Bax/Bak- and caspase-independent, while apoptosis induced by 3 was Bax/Bak-dependent. Reactive oxygen species (ROS) production at the mitochondrial level was a critical step in the antitumor effect of these compounds. PMID:21864808

  16. Mitochondrial calcium uniporter silencing potentiates caspase-independent cell death in MDA-MB-231 breast cancer cells

    SciTech Connect

    Curry, Merril C.; Peters, Amelia A.; Kenny, Paraic A.; Roberts-Thomson, Sarah J.; Monteith, Gregory R.

    2013-05-10

    Highlights: •Some clinical breast cancers are associated with MCU overexpression. •MCU silencing did not alter cell death initiated with the Bcl-2 inhibitor ABT-263. •MCU silencing potentiated caspase-independent cell death initiated by ionomycin. •MCU silencing promoted ionomycin-mediated cell death without changes in bulk Ca{sup 2+}. -- Abstract: The mitochondrial calcium uniporter (MCU) transports free ionic Ca{sup 2+} into the mitochondrial matrix. We assessed MCU expression in clinical breast cancer samples using microarray analysis and the consequences of MCU silencing in a breast cancer cell line. Our results indicate that estrogen receptor negative and basal-like breast cancers are characterized by elevated levels of MCU. Silencing of MCU expression in the basal-like MDA-MB-231 breast cancer cell line produced no change in proliferation or cell viability. However, distinct consequences of MCU silencing were seen on cell death pathways. Caspase-dependent cell death initiated by the Bcl-2 inhibitor ABT-263 was not altered by MCU silencing; whereas caspase-independent cell death induced by the calcium ionophore ionomycin was potentiated by MCU silencing. Measurement of cytosolic Ca{sup 2+} levels showed that the promotion of ionomycin-induced cell death by MCU silencing occurs independently of changes in bulk cytosolic Ca{sup 2+} levels. This study demonstrates that MCU overexpression is a feature of some breast cancers and that MCU overexpression may offer a survival advantage against some cell death pathways. MCU inhibitors may be a strategy to increase the effectiveness of therapies that act through the induction of caspase-independent cell death pathways in estrogen receptor negative and basal-like breast cancers.

  17. Relation between cell death progression, reactive oxygen species production and mitochondrial membrane potential in fermenting Saccharomyces cerevisiae cells under heat-shock conditions.

    PubMed

    Pyatrikas, Darya V; Fedoseeva, Irina V; Varakina, Nina N; Rusaleva, Tatyana M; Stepanov, Alexei V; Fedyaeva, Anna V; Borovskii, Gennadii B; Rikhvanov, Eugene G

    2015-06-01

    Moderate heat shock increased reactive oxygen species (ROS) production that led to cell death in glucose-grown Saccharomyces cerevisiae cells. Conditions that disturb mitochondrial functions such as treatment by uncouplers and petite mutation were shown to inhibit ROS production and protects cell from thermal death. Hence, mitochondria are responsible for ROS production and play an active role in cell death. An increase in ROS production was accompanied by hyperpolarization of inner mitochondrial membrane. All agents suppressing hyperpolarization also suppressed heat-induced ROS production. It was supposed that generation of ROS under moderate heat shock in glucose-grown S. cerevisiae cells is driven by the mitochondrial membrane potential.

  18. Apoptosis Cell Death Effect of Scrophularia Variegata on Breast Cancer Cells via Mitochondrial Intrinsic Pathway

    PubMed Central

    Azadmehr, Abbas; Hajiaghaee, Reza; Baradaran, Behzad; Haghdoost-Yazdi, Hashem

    2015-01-01

    Purpose: Scrophularia variegata M. Beib. (Scrophulariaceae) is an Iranian medicinal plant which is used for various inflammatory disorders in traditional medicine. In this study we evaluated the anti-cancer and cytotoxic effects of the Scrophularia variegata (S. variegata) ethanolic extract on the human breast cancer cell line. Methods: The cytotoxicity effect of the extract on MCF-7 cells was evaluated by MTT assay. In addition, Caspase activity, DNA ladder and Cell death were evaluated by ELISA, gel electrophoresis and Annexin V-FITC/PI staining, respectively. Results: The S. variegata extract showed significant effect cytotoxicity on MCF-7 human breast cancer cell line. Treatment with the extract induced apoptosis on the breast cancer cells by cell cycle arrest in G2/M phase. The results indicated that cytotoxicity activity was associated with an increase of apoptosis as demonstrated by DNA fragmentation as well as an increase of the amount of caspase 3 and caspase 9. In addition, the phytochemical assay showed that the extract had antioxidant capacity and also flavonoids, phenolic compounds and phenyl propanoids were presented in the extract. Conclusion: Our findings indicated that S. variegata extract induced apoptosis via mitochondrial intrinsic pathway on breast cancer by cell cycle arrest in G2/M phase and an increase of caspase 3 and caspase 9. However future studies are needed. PMID:26504768

  19. Rapid generation of mitochondrial superoxide induces mitochondrion-dependent but caspase-independent cell death in hippocampal neuronal cells that morphologically resembles necroptosis

    SciTech Connect

    Fukui, Masayuki; Choi, Hye Joung; Zhu, Bao Ting

    2012-07-15

    Studies in recent years have revealed that excess mitochondrial superoxide production is an important etiological factor in neurodegenerative diseases, resulting from oxidative modifications of cellular lipids, proteins, and nucleic acids. Hence, it is important to understand the mechanism by which mitochondrial oxidative stress causes neuronal death. In this study, the immortalized mouse hippocampal neuronal cells (HT22) in culture were used as a model and they were exposed to menadione (also known as vitamin K{sub 3}) to increase intracellular superoxide production. We found that menadione causes preferential accumulation of superoxide in the mitochondria of these cells, along with the rapid development of mitochondrial dysfunction and cellular ATP depletion. Neuronal death induced by menadione is independent of the activation of the MAPK signaling pathways and caspases. The lack of caspase activation is due to the rapid depletion of cellular ATP. It was observed that two ATP-independent mitochondrial nucleases, namely, AIF and Endo G, are released following menadione exposure. Silencing of their expression using specific siRNAs results in transient suppression (for ∼ 12 h) of mitochondrial superoxide-induced neuronal death. While suppression of the mitochondrial superoxide dismutase expression markedly sensitizes neuronal cells to mitochondrial superoxide-induced cytotoxicity, its over-expression confers strong protection. Collectively, these findings showed that many of the observed features associated with mitochondrial superoxide-induced cell death, including caspase independency, rapid depletion of ATP level, mitochondrial release of AIF and Endo G, and mitochondrial swelling, are distinctly different from those of apoptosis; instead they resemble some of the known features of necroptosis. -- Highlights: ► Menadione causes mitochondrial superoxide accumulation and injury. ► Menadione-induced cell death is caspase-independent, due to rapid depletion of

  20. Reduction in mitochondrial potential constitutes an early irreversible step of programmed lymphocyte death in vivo

    PubMed Central

    1995-01-01

    In a number of experimental systems in which lymphocyte depletion was induced by apoptosis-inducing manipulations, no apoptotic morphology and ladder-type DNA fragmentation were detected among freshly isolated peripheral lymphocytes ex vivo. Here we report that one alteration that can be detected among splenocytes stimulated with lymphocyte-depleting doses of dexamethasone (DEX) in vivo is a reduced uptake of 3,3'dihexyloxacarbocyanine iodide (DiOC6[3]), a fluorochrome which incorporates into cells dependent upon their mitochondrial transmembrane potential (delta psi m). In contrast, ex vivo isolated splenocytes still lacked established signs of programmed cell death (PCD):DNA degradation into high or low molecular weight fragments, ultrastructural changes of chromatin arrangement and endoplasmatic reticulum, loss in viability, or accumulation of intracellular peroxides. Moreover, no changes in cell membrane potential could be detected. A reduced delta psi m has been observed in response to different agents inducing lymphoid cell depletion in vivo (superantigen and glucocorticoids [GC]), in mature T and B lymphocytes, as well as their precursors. DEX treatment in vivo, followed by cytofluorometric purification of viable delta psi mlow splenic T cells ex vivo, revealed that this fraction of cells is irreversibly committed to undergoing DNA fragmentation. Immediately after purification neither delta psi mlow, nor delta psi mhigh cells, exhibit detectable DNA fragmentation. However, after short-term culture (37 degrees C, 1 h) delta psi mlow cells show endonucleolysis, followed by cytolysis several hours later. Incubation of delta psi mlow cells in the presence of excess amount of the GC receptor antagonist RU38486 (which displaces DEX from the GC receptor), cytokines that inhibit DEX-induced cell death, or cycloheximide fails to prevent cytolysis. The antioxidant, N- acetylcysteine, as well as linomide, an agent that effectively inhibits DEX or superantigen

  1. Med13p prevents mitochondrial fission and programmed cell death in yeast through nuclear retention of cyclin C.

    PubMed

    Khakhina, Svetlana; Cooper, Katrina F; Strich, Randy

    2014-09-15

    The yeast cyclin C-Cdk8 kinase forms a complex with Med13p to repress the transcription of genes involved in the stress response and meiosis. In response to oxidative stress, cyclin C displays nuclear to cytoplasmic relocalization that triggers mitochondrial fission and promotes programmed cell death. In this report, we demonstrate that Med13p mediates cyclin C nuclear retention in unstressed cells. Deleting MED13 allows aberrant cytoplasmic cyclin C localization and extensive mitochondrial fragmentation. Loss of Med13p function resulted in mitochondrial dysfunction and hypersensitivity to oxidative stress-induced programmed cell death that were dependent on cyclin C. The regulatory system controlling cyclin C-Med13p interaction is complex. First, a previous study found that cyclin C phosphorylation by the stress-activated MAP kinase Slt2p is required for nuclear to cytoplasmic translocation. This study found that cyclin C-Med13p association is impaired when the Slt2p target residue is substituted with a phosphomimetic amino acid. The second step involves Med13p destruction mediated by the 26S proteasome and cyclin C-Cdk8p kinase activity. In conclusion, Med13p maintains mitochondrial structure, function, and normal oxidative stress sensitivity through cyclin C nuclear retention. Releasing cyclin C from the nucleus involves both its phosphorylation by Slt2p coupled with Med13p destruction.

  2. Pre-B-cell colony-enhancing factor protects against apoptotic neuronal death and mitochondrial damage in ischemia

    PubMed Central

    Wang, Xiaowan; Li, Hailong; Ding, Shinghua

    2016-01-01

    We previously demonstrated that Pre-B-cell colony-enhancing factor (PBEF), also known as nicotinamide phosphoribosyltransferase (NAMPT), the rate-limiting enzyme in mammalian NAD+ biosynthesis pathway, plays a brain and neuronal protective role in ischemic stroke. In this study, we further investigated the mechanism of its neuroprotective effect after ischemia in the primary cultured mouse cortical neurons. Using apoptotic cell death assay, fluorescent imaging, molecular biology, mitochondrial biogenesis measurements and Western blotting analysis, our results show that the overexpression of PBEF in neurons can significantly promote neuronal survival, reduce the translocation of apoptosis inducing factor (AIF) from mitochondria to nuclei and inhibit the activation of capase-3 after glutamate-induced excitotoxicity. We further found that the overexpression of PBEF can suppress glutamate-induced mitochondrial fragmentation, the loss of mitochondrial DNA (mtDNA) content and the reduction of PGC-1 and NRF-1 expressions. Furthermore, these beneficial effects by PBEF are dependent on its enzymatic activity of NAD+ synthesis. In summary, our study demonstrated that PBEF ameliorates ischemia-induced neuronal death through inhibiting caspase-dependent and independent apoptotic signaling pathways and suppressing mitochondrial damage and dysfunction. Our study provides novel insights into the mechanisms underlying the neuroprotective effect of PBEF, and helps to identify potential targets for ischemic stroke therapy. PMID:27576732

  3. Pre-B-cell colony-enhancing factor protects against apoptotic neuronal death and mitochondrial damage in ischemia.

    PubMed

    Wang, Xiaowan; Li, Hailong; Ding, Shinghua

    2016-01-01

    We previously demonstrated that Pre-B-cell colony-enhancing factor (PBEF), also known as nicotinamide phosphoribosyltransferase (NAMPT), the rate-limiting enzyme in mammalian NAD(+) biosynthesis pathway, plays a brain and neuronal protective role in ischemic stroke. In this study, we further investigated the mechanism of its neuroprotective effect after ischemia in the primary cultured mouse cortical neurons. Using apoptotic cell death assay, fluorescent imaging, molecular biology, mitochondrial biogenesis measurements and Western blotting analysis, our results show that the overexpression of PBEF in neurons can significantly promote neuronal survival, reduce the translocation of apoptosis inducing factor (AIF) from mitochondria to nuclei and inhibit the activation of capase-3 after glutamate-induced excitotoxicity. We further found that the overexpression of PBEF can suppress glutamate-induced mitochondrial fragmentation, the loss of mitochondrial DNA (mtDNA) content and the reduction of PGC-1 and NRF-1 expressions. Furthermore, these beneficial effects by PBEF are dependent on its enzymatic activity of NAD(+) synthesis. In summary, our study demonstrated that PBEF ameliorates ischemia-induced neuronal death through inhibiting caspase-dependent and independent apoptotic signaling pathways and suppressing mitochondrial damage and dysfunction. Our study provides novel insights into the mechanisms underlying the neuroprotective effect of PBEF, and helps to identify potential targets for ischemic stroke therapy. PMID:27576732

  4. Leber's hereditary optic neuropathy (LHON) pathogenic mutations induce mitochondrial-dependent apoptotic death in transmitochondrial cells incubated with galactose medium.

    PubMed

    Ghelli, Anna; Zanna, Claudia; Porcelli, Anna Maria; Schapira, Anthony H V; Martinuzzi, Andrea; Carelli, Valerio; Rugolo, Michela

    2003-02-01

    Leber's hereditary optic neuropathy (LHON), a maternally inherited form of central vision loss, is associated with mitochondrial DNA pathogenic point mutations affecting different subunits of complex I. We here report that osteosarcoma-derived cytoplasmic hybrids (cybrid) cell lines harboring one of the three most frequent LHON pathogenic mutations, at positions 11778/ND4, 3460/ND1, and 14484/ND6, undergo cell death when galactose replaces glucose in the medium, contrary to control cybrids that maintain some growth capabilities. This is a well known way to produce a metabolic stress, forcing the cells to rely on the mitochondrial respiratory chain to produce ATP. We demonstrate that LHON cybrid cell death is apoptotic, showing chromatin condensation and nuclear DNA laddering. Moreover, we also document the mitochondrial involvement in the activation of the apoptotic cascade, as shown by the increased release of cytochrome c into the cytosol in LHON cybrid cells as compared with controls. Cybrids bearing the 3460/ND1 and 14484/ND6 mutations seemed more readily prone to undergo apoptosis as compared with the 11778/ND4 mutation. In conclusion, LHON cybrid cells forced by the reduced rate of glycolytic flux to utilize oxidative metabolism are sensitized to an apoptotic death through a mechanism involving mitochondria.

  5. Cellular Stress Induced by Resazurin Leads to Autophagy and Cell Death Via Production of Reactive Oxygen Species and Mitochondrial Impairment

    PubMed Central

    Erikstein, Bjarte Skoe; Hagland, Hanne Røland; Nikolaisen, Julie; Kulawiec, Mariola; Singh, Keshav K.; Gjertsen, Bjørn Tore; Tronstad, Karl Johan

    2010-01-01

    Mitochondrial bioenergetics and reactive oxygen species (ROS) often play important roles in cellular stress mechanisms. In this study we investigated how these factors are involved in the stress response triggered by resazurin (Alamar Blue) in cultured cancer cells. Resazurin is a redox reactive compound widely used as reporter agent in assays of cell biology (e.g. cell viability and metabolic activity) due to its colorimetric and fluorimetric properties. In order to investigate resazurin-induced stress mechanisms we employed cells affording different metabolic and regulatory phenotypes. In HL-60 and Jurkat leukemia cells resazurin caused mitochondrial disintegration, respiratory dysfunction, reduced proliferation, and cell death. These effects were preceded by a burst of ROS, especially in HL-60 cells which also were more sensitive and contained autophagic vesicles. Studies in Rho0 cells (devoid of mitochondrial DNA) indicated that the stress response does not depend on the rates of mitochondrial respiration. The anti-proliferative effect of resazurin was confirmed in native acute myelogenous leukemia (AML) blasts. In conclusion, the data suggest that resazurin triggers cellular ROS production and thereby initiates a stress response leading to mitochondrial dysfunction, reduced proliferation, autophagy and cell degradation. The ability of cells to tolerate this type of stress may be important in toxicity and chemoresistance. PMID:20568117

  6. Mitochondrial Translocation of High Mobility Group Box 1 Facilitates LIM Kinase 2-Mediated Programmed Necrotic Neuronal Death.

    PubMed

    Hyun, Hye-Won; Ko, Ah-Reum; Kang, Tae-Cheon

    2016-01-01

    High mobility group box 1 (HMGB1) acts a signaling molecule regulating a wide range of inflammatory responses in extracellular space. HMGB1 also stabilizes nucleosomal structure and facilitates gene transcription. Under pathophysiological conditions, nuclear HMGB1 is immediately transported to the cytoplasm through chromosome region maintenance 1 (CRM1). Recently, we have reported that up-regulation of LIM kinase 2 (LIMK2) expression induces HMGB1 export from neuronal nuclei during status epilepticus (SE)-induced programmed neuronal necrosis in the rat hippocampus. Thus, we investigated whether HMGB1 involves LIMK2-mediated programmed neuronal necrosis, but such role is not reported. In the present study, SE was induced by pilocarpine in rats that were intracerebroventricularly infused with saline, control siRNA, LIMK2 siRNA or leptomycin B (LMB, a CRM1 inhibitor) prior to SE induction. Thereafter, we performed Fluoro-Jade B staining, western blots and immunohistochemical studies. LIMK2 knockdown effectively attenuated SE-induced neuronal death and HMGB1 import into mitochondria accompanied by inhibiting nuclear HMGB1 release and abnormal mitochondrial elongation. LMB alleviated SE-induced neuronal death and nuclear HMGB1 release. However, LMB did not prevent mitochondrial elongation induced by SE, but inhibited the HMGB1 import into mitochondria. The efficacy of LMB was less effective to attenuate SE-induced neuronal death than that of LIMK2 siRNA. These findings indicate that nuclear HMGB1 release and the subsequent mitochondrial import may facilitate and deteriorate programmed necrotic neuronal deaths. The present data suggest that the nuclear HMGB1 release via CRM1 may be a potential therapeutic target for the programmed necrotic neuronal death induced by SE. PMID:27147971

  7. Troglitazone, but not rosiglitazone, damages mitochondrial DNA and induces mitochondrial dysfunction and cell death in human hepatocytes

    SciTech Connect

    Rachek, Lyudmila I.; Yuzefovych, Larysa V.; LeDoux, Susan P.; Julie, Neil L.; Wilson, Glenn L.

    2009-11-01

    Thiazolidinediones (TZDs), such as troglitazone (TRO) and rosiglitazone (ROSI), improve insulin resistance by acting as ligands for the nuclear receptor peroxisome proliferator-activated receptor-gamma (PPARgamma). TRO was withdrawn from the market because of reports of serious hepatotoxicity. A growing body of evidence suggests that TRO caused mitochondrial dysfunction and induction of apoptosis in human hepatocytes but its mechanisms of action remain unclear. We hypothesized that damage to mitochondrial DNA (mtDNA) is an initiating event involved in TRO-induced mitochondrial dysfunction and hepatotoxicity. Primary human hepatocytes were exposed to TRO and ROSI. The results obtained revealed that TRO, but not ROSI at equimolar concentrations, caused a substantial increase in mtDNA damage and decreased ATP production and cellular viability. The reactive oxygen species (ROS) scavenger, N-acetyl cystein (NAC), significantly diminished the TRO-induced cytotoxicity, suggesting involvement of ROS in TRO-induced hepatocyte cytotoxicity. The PPARgamma antagonist (GW9662) did not block the TRO-induced decrease in cell viability, indicating that the TRO-induced hepatotoxicity is PPARgamma-independent. Furthermore, TRO induced hepatocyte apoptosis, caspase-3 cleavage and cytochrome c release. Targeting of a DNA repair protein to mitochondria by protein transduction using a fusion protein containing the DNA repair enzyme Endonuclease III (EndoIII) from Escherichia coli, a mitochondrial translocation sequence (MTS) and the protein transduction domain (PTD) from HIV-1 TAT protein protected hepatocytes against TRO-induced toxicity. Overall, our results indicate that significant mtDNA damage caused by TRO is a prime initiator of the hepatoxicity caused by this drug.

  8. Mitochondrial Bioenergetic Alterations in Mouse Neuroblastoma Cells Infected with Sindbis Virus: Implications to Viral Replication and Neuronal Death

    PubMed Central

    Silva da Costa, Leandro; Pereira da Silva, Ana Paula; Da Poian, Andrea T.; El-Bacha, Tatiana

    2012-01-01

    The metabolic resources crucial for viral replication are provided by the host. Details of the mechanisms by which viruses interact with host metabolism, altering and recruiting high free-energy molecules for their own replication, remain unknown. Sindbis virus, the prototype of and most widespread alphavirus, causes outbreaks of arthritis in humans and serves as a model for the study of the pathogenesis of neurological diseases induced by alphaviruses in mice. In this work, respirometric analysis was used to evaluate the effects of Sindbis virus infection on mitochondrial bioenergetics of a mouse neuroblastoma cell lineage, Neuro 2a. The modulation of mitochondrial functions affected cellular ATP content and this was synchronous with Sindbis virus replication cycle and cell death. At 15 h, irrespective of effects on cell viability, viral replication induced a decrease in oxygen consumption uncoupled to ATP synthesis and a 36% decrease in maximum uncoupled respiration, which led to an increase of 30% in the fraction of oxygen consumption used for ATP synthesis. Decreased proton leak associated to complex I respiration contributed to the apparent improvement of mitochondrial function. Cellular ATP content was not affected by infection. After 24 h, mitochondria dysfunction was clearly observed as maximum uncoupled respiration reduced 65%, along with a decrease in the fraction of oxygen consumption used for ATP synthesis. Suppressed respiration driven by complexes I- and II-related substrates seemed to play a role in mitochondrial dysfunction. Despite the increase in glucose uptake and glycolytic flux, these changes were followed by a 30% decrease in ATP content and neuronal death. Taken together, mitochondrial bioenergetics is modulated during Sindbis virus infection in such a way as to favor ATP synthesis required to support active viral replication. These early changes in metabolism of Neuro 2a cells may form the molecular basis of neuronal dysfunction and Sindbis

  9. Premature Death in Podospora Anserina: Sporadic Accumulation of the Deleted Mitochondrial Genome, Translational Parameters and Innocuity of the Mating Types

    PubMed Central

    Contamine, V.; Lecellier, G.; Belcour, L.; Picard, M.

    1996-01-01

    The Podospora anserina premature death syndrome was described as early growth arrest caused by a site-specific deletion of the mitochondrial genome (mtDNA) and occurring in strains displaying the genotype AS1-4 mat-. The AS1-4 mutation lies in a gene encoding a cytosolic ribosomal protein, while mat- is one of the two forms (mat- and mat+) of the mating-type locus. Here we show that, depending on culture conditions, death due to the accumulation of the deleted mtDNA molecule can occur in the AS1-4 mat+ context and can be delayed in the AS1-4 mat- background. Furthermore, we show that premature death and the classical senescence process are mutually exclusive. Several approaches permit the identification of the mat-linked gene involved in the appearance of premature death. This gene, rmp, exhibits two natural alleles, rmp- linked to mat- and rmp+ linked to mat+. The first is probably functional while the second probably carries a nonsense mutation and is sporadically expressed through natural suppression. A model is proposed that emphasizes the roles played by the AS1-4 mutation, the rmp gene, and environmental conditions in the accumulation of the deleted mitochondrial genome characteristic of this syndrome. PMID:8889519

  10. Decision-making in a death investigation: Emotion, families and the coroner.

    PubMed

    Tait, Gordon; Carpenter, Belinda; Quadrelli, Carol; Barnes, Michael

    2016-03-01

    The role of the coroner in common law countries such as Australia, England, Canada and New Zealand is to preside over death investigations where there is uncertainty as to the manner of death, a need to identify the deceased, a death of unknown cause, or a violent or unnatural death. The vast majority of these deaths are not suspicious and thus require coroners to engage with grieving families who have been thrust into a legal process through the misfortune of a loved one's sudden or unexpected death. In this research, 10 experienced coroners discussed how they negotiated the grief and trauma evident in a death investigation. In doing so, they articulated two distinct ways in which legal officers engaged with emotions, which are also evident in the literature. The first engages the script of judicial dispassion, articulating a hierarchical relationship between reason and emotion, while the second introduces an ethic of care via the principles of therapeutic jurisprudence, and thus offers a challenge to the role of emotion in the personae of the professional judicial officer. By using Hochschild's work on the sociology of emotions, this article discusses the various ways in which coroners manage the emotion of a death investigation through emotion work. While emotional distance may be an understandable response by coroners to the grief and trauma experienced by families and directed at cleaner coronial decision-making, the article concludes that coroners may be better served by offering emotions such as sympathy, consideration and compassion directly to the family in those situations where families are struggling to accept, or are resistant to, coroners' decisions. PMID:27323635

  11. Role of the Mitochondrial Calcium Uniporter in Rat Hippocampal Neuronal Death After Pilocarpine-Induced Status Epilepticus.

    PubMed

    Wang, Cui; Xie, Nanchang; Wang, Yunlong; Li, Yulin; Ge, Xinjie; Wang, Menglu

    2015-08-01

    The mitochondrial calcium uniporter (MCU) is reportedly involved in oxidative stress, apoptosis, and many neurological diseases. However, the role of the MCU in epilepsy remains unknown. In this study, we found that the MCU inhibitor Ru360 significantly attenuated neuronal death and exerted an anti-apoptotic effect on rat hippocampal neurons after pilocarpine-induced status epilepticus (SE), while the MCU activator spermine increased seizure-induced neuronal death and apoptosis. In addition, Ru360 decreased the level of seizure-induced reactive oxygen species (ROS) in mitochondria isolated from rat hippocampi. Moreover, Ru360 restored the altered mitochondrial membrane potential and cytochrome c (CytC) release in epileptic hippocampi. However, spermine treatment exerted an opposite effect on seizure-induced ROS production and mitochondrial membrane potential alteration and CytC release compared with Ru360 treatment. Altogether, the findings of this study suggest that MCU inhibition exerts a neuroprotective effect on seizure-induced brain injury possibly through the mitochondria/ROS/CytC pathway.

  12. GILZ overexpression attenuates endoplasmic reticulum stress-mediated cell death via the activation of mitochondrial oxidative phosphorylation.

    PubMed

    André, Fanny; Corazao-Rozas, Paola; Idziorek, Thierry; Quesnel, Bruno; Kluza, Jérome; Marchetti, Philippe

    2016-09-16

    The Glucocorticoïd-induced leucine zipper (GILZ) protein has profound anti-inflammatory activities in haematopoietic cells. GILZ regulates numerous signal transduction pathways involved in proliferation and survival of normal and neoplastic cells. Here, we have demonstrated the potential of GILZ in alleviating apoptosis induced by ER stress inducers. Whereas the glucocorticoid, dexamethasone, protects from tunicamycin-induced cell death, silencing endogeneous GILZ in dexamethasone-treated cancer cells alter the capacity of glucocorticoids to protect from tunicamycin-mediated apoptosis. Under ER stress conditions, overexpression of GILZ significantly reduced activation of mitochondrial pathway of apoptosis by maintaining Bcl-xl level. GILZ protein affects the UPR signaling shifting the balance towards pro-survival signals as judged by down-regulation of CHOP, ATF4, XBP1s mRNA and increase in GRP78 protein level. Interestingly, GILZ sustains high mitochondrial OXPHOS during ER stress and cytoprotection mediated by GILZ is abolished in cells depleted of mitochondrial DNA, which are OXPHOS-deficient. These findings reveal a new role of GILZ, which acts as a cytoprotector against ER stress through a pathway involving mitochondrial OXPHOS. PMID:27416758

  13. Rapid generation of mitochondrial superoxide induces mitochondrion-dependent but caspase-independent cell death in hippocampal neuronal cells that morphologically resembles necroptosis☆

    PubMed Central

    Fukui, Masayuki; Choi, Hye Joung; Zhu, Bao Ting

    2013-01-01

    Studies in recent years have revealed that excess mitochondrial superoxide production is an important etiological factor in neurodegenerative diseases, resulting from oxidative modifications of cellular lipids, proteins, and nucleic acids. Hence, it is important to understand the mechanism by which mitochondrial oxidative stress causes neuronal death. In this study, the immortalized mouse hippocampal neuronal cells (HT22) in culture were used as a model and they were exposed to menadione (also known as vitamin K3) to increase intracellular superoxide production. We found that menadione causes preferential accumulation of superoxide in the mitochondria of these cells, along with the rapid development of mitochondrial dysfunction and cellular ATP depletion. Neuronal death induced by menadione is independent of the activation of the MAPK signaling pathways and caspases. The lack of caspase activation is due to the rapid depletion of cellular ATP. It was observed that two ATP-independent mitochondrial nucleases, namely, AIF and Endo G, are released following menadione exposure. Silencing of their expression using specific siRNAs results in transient suppression (for ~12 h) of mitochondrial superoxide-induced neuronal death. While suppression of the mitochondrial superoxide dismutase expression markedly sensitizes neuronal cells to mitochondrial superoxide-induced cytotoxicity, its over-expression confers strong protection. Collectively, these findings showed that many of the observed features associated with mitochondrial superoxide-induced cell death, including caspase independency, rapid depletion of ATP level, mitochondrial release of AIF and Endo G, and mitochondrial swelling, are distinctly different from those of apoptosis; instead they resemble some of the known features of necroptosis. PMID:22575170

  14. Parallel damage in mitochondrial and lysosomal compartments promotes efficient cell death with autophagy: The case of the pentacyclic triterpenoids

    PubMed Central

    Martins, Waleska K.; Costa, Érico T.; Cruz, Mário C.; Stolf, Beatriz S.; Miotto, Ronei; Cordeiro, Rodrigo M.; Baptista, Maurício S.

    2015-01-01

    The role of autophagy in cell death is still controversial and a lot of debate has concerned the transition from its pro-survival to its pro-death roles. The similar structure of the triterpenoids Betulinic (BA) and Oleanolic (OA) acids allowed us to prove that this transition involves parallel damage in mitochondria and lysosome. After treating immortalized human skin keratinocytes (HaCaT) with either BA or OA, we evaluated cell viability, proliferation and mechanism of cell death, function and morphology of mitochondria and lysosomes, and the status of the autophagy flux. We also quantified the interactions of BA and OA with membrane mimics, both in-vitro and in-silico. Essentially, OA caused mitochondrial damage that relied on autophagy to rescue cellular homeostasis, which failed upon lysosomal inhibition by Chloroquine or Bafilomycin-A1. BA caused parallel damage on mitochondria and lysosome, turning autophagy into a destructive process. The higher cytotoxicity of BA correlated with its stronger efficiency in damaging membrane mimics. Based on these findings, we underlined the concept that autophagy will turn into a destructive outcome when there is parallel damage in mitochondrial and lysosomal membranes. We trust that this concept will help the development of new drugs against aggressive cancers. PMID:26213355

  15. Mouse Cytotoxic T Cell-derived Granzyme B Activates the Mitochondrial Cell Death Pathway in a Bim-dependent Fashion*

    PubMed Central

    Catalán, Elena; Jaime-Sánchez, Paula; Aguiló, Nacho; Simon, Markus M.; Froelich, Christopher J.; Pardo, Julián

    2015-01-01

    Cytotoxic T cells (Tc) use perforin and granzyme B (gzmB) to kill virus-infected cells and cancer cells. Recent evidence suggests that human gzmB primarily induces apoptosis via the intrinsic mitochondrial pathway by either cleaving Bid or activating Bim leading to the activation of Bak/Bax and subsequent generation of active caspase-3. In contrast, mouse gzmB is thought to predominantly induce apoptosis by directly processing pro-caspase-3. However, in certain mouse cell types gzmB-mediated apoptosis mainly occurs via the mitochondrial pathway. To investigate whether Bim is involved under the latter conditions, we have now employed ex vivo virus-immune mouse Tc that selectively kill by using perforin and gzmB (gzmB+Tc) as effector cells and wild type as well as Bim- or Bak/Bax-deficient spontaneously (3T9) or virus-(SV40) transformed mouse embryonic fibroblast cells as targets. We show that gzmB+Tc-mediated apoptosis (phosphatidylserine translocation, mitochondrial depolarization, cytochrome c release, and caspase-3 activation) was severely reduced in 3T9 cells lacking either Bim or both Bak and Bax. This outcome was related to the ability of Tc cells to induce the degradation of Mcl-1 and Bcl-XL, the anti-apoptotic counterparts of Bim. In contrast, gzmB+Tc-mediated apoptosis was not affected in SV40-transformed mouse embryonic fibroblast cells lacking Bak/Bax. The data provide evidence that Bim participates in mouse gzmB+Tc-mediated apoptosis of certain targets by activating the mitochondrial pathway and suggest that the mode of cell death depends on the target cell. Our results suggest that the various molecular events leading to transformation and/or immortalization of cells have an impact on their relative resistance to the multiple gzmB+Tc-induced death pathways. PMID:25605735

  16. 5-Hydroxy-7-Methoxyflavone Triggers Mitochondrial-Associated Cell Death via Reactive Oxygen Species Signaling in Human Colon Carcinoma Cells

    PubMed Central

    Paul, Souren; Jakhar, Rekha; Han, Jaehong; Kang, Sun Chul

    2016-01-01

    Plant-derived compounds are an important source of clinically useful anti-cancer agents. Chrysin, a biologically active flavone found in many plants, has limited usage for cancer chemotherapeutics due to its poor oral bioavailability. 5-Hydroxy-7-methoxyflavone (HMF), an active natural chrysin derivative found in various plant sources, is known to modulate several biological activities. However, the mechanism underlying HMF-induced apoptotic cell death in human colorectal carcinoma cells in vitro is still unknown. Herein, HMF was shown to be capable of inducing cytotoxicity in HCT-116 cells and induced cell death in a dose-dependent manner. Treatment of HCT-116 cells with HMF caused DNA damage and triggered mitochondrial membrane perturbation accompanied by Cyt c release, down-regulation of Bcl-2, activation of BID and Bax, and caspase-3-mediated apoptosis. These results show that ROS generation by HMF was the crucial mediator behind ER stress induction, resulting in intracellular Ca2+ release, JNK phosphorylation, and activation of the mitochondrial apoptosis pathway. Furthermore, time course study also reveals that HMF treatment leads to increase in mitochondrial and cytosolic ROS generation and decrease in antioxidant enzymes expression. Temporal upregulation of IRE1-α expression and JNK phosphorylation was noticed after HMF treatment. These results were further confirmed by pre-treatment with the ROS scavenger N-acetyl-l-cysteine (NAC), which completely reversed the effects of HMF treatment by preventing lipid peroxidation, followed by abolishment of JNK phosphorylation and attenuation of apoptogenic marker proteins. These results emphasize that ROS generation by HMF treatment regulates the mitochondrial-mediated apoptotic signaling pathway in HCT-116 cells, demonstrating HMF as a promising pro-oxidant therapeutic candidate for targeting colorectal cancer. PMID:27116119

  17. Paramedic accuracy in using a decision support algorithm when recognising adult death: a prospective cohort study

    PubMed Central

    Jones, T; Woollard, M

    2003-01-01

    Method: This prospective 16 month cohort study evaluated 188 events of recognition of adult death (ROAD) by paramedics in the period from November 1999 to February 2001. Results: Of 188 ROAD applications, errors were made in 13 cases (6.9%, 95% CI 3.7 to 11.5. Additionally, there was one adverse clinical incident associated with a case in which ROAD was applied (0.5%, 95% CI 0.01 to 2.9%). ECG strips were unavailable for eight cases, although ambulance records indicated a rhythm of asystole for each of these. Assuming this diagnosis was correct, ROAD was used 174 times without errors (93%, 95% CI 88 to 96%). Assuming that it was not, the ROAD protocol was applied without errors in 166 cases (88.3%, 95% CI 82.8 to 92.5%). None of the errors made appeared to be attributable to poor clinical decision making, compromised treatment, or changed patient outcome. The mean on-scene time for ambulance crews using the ROAD policy was 60 minutes. Conclusion: Paramedics can accurately apply a decision support algorithm when recognising adult death. It could be argued that the attendance of a medical practitioner to confirm death is therefore an inappropriate use of such personnel and may result in unnecessarily protracted on-scene times for ambulance crews. Further research is required to confirm this, and to determine the proportion of patients suitable for recognition of adult death who are actually identified as such by paramedics. PMID:12954697

  18. Mitochondrial dysfunction and cell death in neurodegenerative diseases through nitroxidative stress.

    PubMed

    Akbar, Mohammed; Essa, Musthafa Mohamed; Daradkeh, Ghazi; Abdelmegeed, Mohamed A; Choi, Youngshim; Mahmood, Lubna; Song, Byoung-Joon

    2016-04-15

    Mitochondria are important for providing cellular energy ATP through the oxidative phosphorylation pathway. They are also critical in regulating many cellular functions including the fatty acid oxidation, the metabolism of glutamate and urea, the anti-oxidant defense, and the apoptosis pathway. Mitochondria are an important source of reactive oxygen species leaked from the electron transport chain while they are susceptible to oxidative damage, leading to mitochondrial dysfunction and tissue injury. In fact, impaired mitochondrial function is commonly observed in many types of neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease, Huntington's disease, alcoholic dementia, brain ischemia-reperfusion related injury, and others, although many of these neurological disorders have unique etiological factors. Mitochondrial dysfunction under many pathological conditions is likely to be promoted by increased nitroxidative stress, which can stimulate post-translational modifications (PTMs) of mitochondrial proteins and/or oxidative damage to mitochondrial DNA and lipids. Furthermore, recent studies have demonstrated that various antioxidants, including naturally occurring flavonoids and polyphenols as well as synthetic compounds, can block the formation of reactive oxygen and/or nitrogen species, and thus ultimately prevent the PTMs of many proteins with improved disease conditions. Therefore, the present review is aimed to describe the recent research developments in the molecular mechanisms for mitochondrial dysfunction and tissue injury in neurodegenerative diseases and discuss translational research opportunities. PMID:26883165

  19. JNK interaction with Sab mediates ER stress induced inhibition of mitochondrial respiration and cell death.

    PubMed

    Win, S; Than, T A; Fernandez-Checa, J C; Kaplowitz, N

    2014-01-09

    Our aim was to better understand the mechanism and importance of sustained c-Jun N-terminal kinase (JNK) activation in endoplasmic reticulum (ER) stress and effects of ER stress on mitochondria by determining the role of mitochondrial JNK binding protein, Sab. Tunicamycin or brefeldin A induced a rapid and marked decline in basal mitochondrial respiration and reserve-capacity followed by delayed mitochondrial-mediated apoptosis. Knockdown of mitochondrial Sab prevented ER stress-induced sustained JNK activation, impaired respiration, and apoptosis, but did not alter the magnitude or time course of activation of ER stress pathways. P-JNK plus adenosine 5'-triphosphate (ATP) added to isolated liver mitochondria promoted superoxide production, which was amplified by addition of calcium and inhibited by a blocking peptide corresponding to the JNK binding site on Sab (KIM1). This peptide also blocked tunicamycin-induced inhibition of cellular respiration. In conclusion, ER stress triggers an interaction of JNK with mitochondrial Sab, which leads to impaired respiration and increased mitochondrial reactive oxygen species, sustaining JNK activation culminating in apoptosis.

  20. Mental competence and end-of-life decision making: death row volunteering and euthanasia.

    PubMed

    Harrington, C Lee

    2004-12-01

    This article reports on a qualitative study of defense attorneys' perceptions of the mental competence or rationality of death row inmates' decisions to waive habeas appeals and proceed directly to execution. Interviews were conducted with twenty attorneys who have either directly represented or been closely involved with would-be volunteers. Through analytic comparison with another end-of-life decision, euthanasia, this article reports on four themes from the interviews: (a) attorneys' perceptions of the legal standard of competence, (b) their perceptions of the competency evaluation process, (c) implications of competing interpretive frames (i.e., volunteering vs. suicide), and (d) the rationality of decisions to waive appeals. Implications of research findings, particularly in terms of recent restructured models of competence, are also discussed.

  1. [Death].

    PubMed

    Ribas, Jordi Domingo

    2003-12-01

    Intercultural factors are essential for reflection. In this article, the authors deals with a more direct vision on the special edition about Grief and Mourning, about the topic which lies in the depths of all of our consciences: death and the question what lies beyond death? The author provides us elements to reflect about concepts, some accepted in various cases, rejected in others, but always polemical, which help us to penetrate farther into the real mystery of life: death and what follows death.

  2. Enhancing mitochondrial calcium buffering capacity reduces aggregation of misfolded SOD1 and motor neuron cell death without extending survival in mouse models of inherited amyotrophic lateral sclerosis.

    PubMed

    Parone, Philippe A; Da Cruz, Sandrine; Han, Joo Seok; McAlonis-Downes, Melissa; Vetto, Anne P; Lee, Sandra K; Tseng, Eva; Cleveland, Don W

    2013-03-13

    Mitochondria have been proposed as targets for toxicity in amyotrophic lateral sclerosis (ALS), a progressive, fatal adult-onset neurodegenerative disorder characterized by the selective loss of motor neurons. A decrease in the capacity of spinal cord mitochondria to buffer calcium (Ca(2+)) has been observed in mice expressing ALS-linked mutants of SOD1 that develop motor neuron disease with many of the key pathological hallmarks seen in ALS patients. In mice expressing three different ALS-causing SOD1 mutants, we now test the contribution of the loss of mitochondrial Ca(2+)-buffering capacity to disease mechanism(s) by eliminating ubiquitous expression of cyclophilin D, a critical regulator of Ca(2+)-mediated opening of the mitochondrial permeability transition pore that determines mitochondrial Ca(2+) content. A chronic increase in mitochondrial buffering of Ca(2+) in the absence of cyclophilin D was maintained throughout disease course and was associated with improved mitochondrial ATP synthesis, reduced mitochondrial swelling, and retention of normal morphology. This was accompanied by an attenuation of glial activation, reduction in levels of misfolded SOD1 aggregates in the spinal cord, and a significant suppression of motor neuron death throughout disease. Despite this, muscle denervation, motor axon degeneration, and disease progression and survival were unaffected, thereby eliminating mutant SOD1-mediated loss of mitochondrial Ca(2+) buffering capacity, altered mitochondrial morphology, motor neuron death, and misfolded SOD1 aggregates, as primary contributors to disease mechanism for fatal paralysis in these models of familial ALS. PMID:23486940

  3. P21Cip1 Protects against Oxidative Stress by Suppressing ER Dependent Activation of Mitochondrial Death Pathways

    PubMed Central

    Vitiello, Peter F.; Wu, Yu-Chieh M.; Staversky, Rhonda J.; O’Reilly, Michael A.

    2009-01-01

    Although it is well established that the cell cycle inhibitor p21 protects against genotoxic stress by preventing the replication of damaged DNA, recent studies have shown cytoplasmic forms can also protect. It protects by delaying the loss of the anti-apoptotic proteins, Mcl-1 and Bcl-XL; however, the mechanism of regulation is unknown. Utilizing hyperoxia as a model of chronic oxidative stress and DNA damage, p21 was detected in the nucleus and cytoplasm and cytoplasmic expression of p21 was sufficient for cytoprotection. P21 was enriched in a subcellular fraction containing mitochondria and endoplasmic reticulum (ER), suggesting that it may be coordinating ER and mitochondrial stress pathways. Consistent with this, p21 suppressed hyperoxic downregulation of BiP and subsequent activation ER stress signaling which effected Mcl-1, but not Bcl-XL; though both inhibited hyperoxic cell death. Taken together, these data show that p21 integrates the DNA damage response with ER stress signaling which then regulates mitochondrial death pathways during chronic genotoxic stress. PMID:18948188

  4. The CT20 peptide causes detachment and death of metastatic breast cancer cells by promoting mitochondrial aggregation and cytoskeletal disruption

    PubMed Central

    Lee, M W; Bassiouni, R; Sparrow, N A; Iketani, A; Boohaker, R J; Moskowitz, C; Vishnubhotla, P; Khaled, A S; Oyer, J; Copik, A; Fernandez-Valle, C; Perez, J M; Khaled, A R

    2014-01-01

    Metastasis accounts for most deaths from breast cancer, driving the need for new therapeutics that can impede disease progression. Rationally designed peptides that take advantage of cancer-specific differences in cellular physiology are an emerging technology that offer promise as a treatment for metastatic breast cancer. We developed CT20p, a hydrophobic peptide based on the C terminus of Bax that exhibits similarities with antimicrobial peptides, and previously reported that CT20p has unique cytotoxic actions independent of full-length Bax. In this study, we identified the intracellular actions of CT20p which precede cancer cell-specific detachment and death. Previously, we found that CT20p migrated in the heavy membrane fractions of cancer cell lysates. Here, using MDA-MB-231 breast cancer cells, we demonstrated that CT20p localizes to the mitochondria, leading to fusion-like aggregation and mitochondrial membrane hyperpolarization. As a result, the distribution and movement of mitochondria in CT20p-treated MDA-MB-231 cells was markedly impaired, particularly in cell protrusions. In contrast, CT20p did not associate with the mitochondria of normal breast epithelial MCF-10A cells, causing little change in the mitochondrial membrane potential, morphology or localization. In MDA-MB-231 cells, CT20p triggered cell detachment that was preceded by decreased levels of α5β1 integrins and reduced F-actin polymerization. Using folate-targeted nanoparticles to encapsulate and deliver CT20p to murine tumors, we achieved significant tumor regression within days of peptide treatment. These results suggest that CT20p has application in the treatment of metastatic disease as a cancer-specific therapeutic peptide that perturbs mitochondrial morphology and movement ultimately culminating in disruption of the actin cytoskeleton, cell detachment, and loss of cell viability. PMID:24853427

  5. Role of mitochondrial permeability transition in human renal tubular epithelial cell death induced by aristolochic acid

    SciTech Connect

    Qi Xinming; Cai Yan; Gong Likun; Liu Linlin; Chen Fangping; Xiao Ying; Wu Xiongfei; Li Yan; Xue Xiang |; Ren Jin . E-mail: cdser_simm@mail.shcnc.ac.cn

    2007-07-01

    Aristolochic acid (AA), a natural nephrotoxin and carcinogen, can induce a progressive tubulointerstitial nephropathy. However, the mechanism by which AA causes renal injury remains largely unknown. Here we reported that the mitochondrial permeability transition (MPT) plays an important role in the renal injury induced by aristolochic acid I (AAI). We found that in the presence of Ca{sup 2+}, AAI caused mitochondrial swelling, leakage of Ca{sup 2+}, membrane depolarization, and release of cytochrome c in isolated kidney mitochondria. These alterations were suppressed by cyclosporin A (CsA), an agent known to inhibit MPT. Culture of HK-2 cell, a human renal tubular epithelial cell line for 24 h with AAI caused a decrease in cellular ATP, mitochondrial membrane depolarization, cytochrome c release, and increase of caspase 3 activity. These toxic effects of AAI were attenuated by CsA and bongkrekic acid (BA), another specific MPT inhibitor. Furthermore, AAI greatly inhibited the activity of mitochondrial adenine nucleotide translocator (ANT) in isolated mitochondria. We suggested that ANT may mediate, at least in part, the AAI-induced MPT. Taken together, these results suggested that MPT plays a critical role in the pathogenesis of HK-2 cell injury induced by AAI and implied that MPT might contribute to human nephrotoxicity of aristolochic acid.

  6. Water-Soluble Coenzyme Q10 Inhibits Nuclear Translocation of Apoptosis Inducing Factor and Cell Death Caused by Mitochondrial Complex I Inhibition

    PubMed Central

    Li, Haining; Chen, Guisheng; Ma, Wanrui; Li, Ping-An Andy

    2014-01-01

    The objectives of the study were to explore the mechanism of rotenone-induced cell damage and to examine the protective effects of water-soluble Coenzyme Q10 (CoQ10) on the toxic effects of rotenone. Murine hippocampal HT22 cells were cultured with mitochondrial complex I inhibitor rotenone. Water-soluble CoQ10 was added to the culture media 3 h prior to the rotenone incubation. Cell viability was determined by alamar blue, reactive oxygen species (ROS) production by dihydroethidine (DHE) and mitochondrial membrane potential by tetramethyl rhodamine methyl ester (TMRM). Cytochrome c, caspase-9 and apoptosis-inducing factor (AIF) were measured using Western blotting after 24 h rotenone incubation. Rotenone caused more than 50% of cell death, increased ROS production, AIF nuclear translocation and reduction in mitochondrial membrane potential, but failed to cause mitochondrial cytochrome c release and caspase-9 activation. Pretreatment with water-soluble CoQ10 enhanced cell viability, decreased ROS production, maintained mitochondrial membrane potential and prevented AIF nuclear translocation. The results suggest that rotenone activates a mitochondria-initiated, caspase-independent cell death pathway. Water-soluble CoQ10 reduces ROS accumulation, prevents the fall of mitochondrial membrane potential, and inhibits AIF translocation and subsequent cell death. PMID:25089873

  7. SLC25A23 augments mitochondrial Ca²⁺ uptake, interacts with MCU, and induces oxidative stress-mediated cell death.

    PubMed

    Hoffman, Nicholas E; Chandramoorthy, Harish C; Shanmughapriya, Santhanam; Zhang, Xueqian Q; Vallem, Sandhya; Doonan, Patrick J; Malliankaraman, Karthik; Guo, Shuchi; Rajan, Sudarsan; Elrod, John W; Koch, Walter J; Cheung, Joseph Y; Madesh, Muniswamy

    2014-03-01

    Emerging findings suggest that two lineages of mitochondrial Ca(2+) uptake participate during active and resting states: 1) the major eukaryotic membrane potential-dependent mitochondrial Ca(2+) uniporter and 2) the evolutionarily conserved exchangers and solute carriers, which are also involved in ion transport. Although the influx of Ca(2+) across the inner mitochondrial membrane maintains metabolic functions and cell death signal transduction, the mechanisms that regulate mitochondrial Ca(2+) accumulation are unclear. Solute carriers--solute carrier 25A23 (SLC25A23), SLC25A24, and SLC25A25--represent a family of EF-hand-containing mitochondrial proteins that transport Mg-ATP/Pi across the inner membrane. RNA interference-mediated knockdown of SLC25A23 but not SLC25A24 and SLC25A25 decreases mitochondrial Ca(2+) uptake and reduces cytosolic Ca(2+) clearance after histamine stimulation. Ectopic expression of SLC25A23 EF-hand-domain mutants exhibits a dominant-negative phenotype of reduced mitochondrial Ca(2+) uptake. In addition, SLC25A23 interacts with mitochondrial Ca(2+) uniporter (MCU; CCDC109A) and MICU1 (CBARA1) while also increasing IMCU. In addition, SLC25A23 knockdown lowers basal mROS accumulation, attenuates oxidant-induced ATP decline, and reduces cell death. Further, reconstitution with short hairpin RNA-insensitive SLC25A23 cDNA restores mitochondrial Ca(2+) uptake and superoxide production. These findings indicate that SLC25A23 plays an important role in mitochondrial matrix Ca(2+) influx.

  8. Ubiquinone-binding site mutagenesis reveals the role of mitochondrial complex II in cell death initiation.

    PubMed

    Kluckova, K; Sticha, M; Cerny, J; Mracek, T; Dong, L; Drahota, Z; Gottlieb, E; Neuzil, J; Rohlena, J

    2015-01-01

    Respiratory complex II (CII, succinate dehydrogenase, SDH) inhibition can induce cell death, but the mechanistic details need clarification. To elucidate the role of reactive oxygen species (ROS) formation upon the ubiquinone-binding (Qp) site blockade, we substituted CII subunit C (SDHC) residues lining the Qp site by site-directed mutagenesis. Cell lines carrying these mutations were characterized on the bases of CII activity and exposed to Qp site inhibitors MitoVES, thenoyltrifluoroacetone (TTFA) and Atpenin A5. We found that I56F and S68A SDHC variants, which support succinate-mediated respiration and maintain low intracellular succinate, were less efficiently inhibited by MitoVES than the wild-type (WT) variant. Importantly, associated ROS generation and cell death induction was also impaired, and cell death in the WT cells was malonate and catalase sensitive. In contrast, the S68A variant was much more susceptible to TTFA inhibition than the I56F variant or the WT CII, which was again reflected by enhanced ROS formation and increased malonate- and catalase-sensitive cell death induction. The R72C variant that accumulates intracellular succinate due to compromised CII activity was resistant to MitoVES and TTFA treatment and did not increase ROS, even though TTFA efficiently generated ROS at low succinate in mitochondria isolated from R72C cells. Similarly, the high-affinity Qp site inhibitor Atpenin A5 rapidly increased intracellular succinate in WT cells but did not induce ROS or cell death, unlike MitoVES and TTFA that upregulated succinate only moderately. These results demonstrate that cell death initiation upon CII inhibition depends on ROS and that the extent of cell death correlates with the potency of inhibition at the Qp site unless intracellular succinate is high. In addition, this validates the Qp site of CII as a target for cell death induction with relevance to cancer therapy. PMID:25950479

  9. Ubiquinone-binding site mutagenesis reveals the role of mitochondrial complex II in cell death initiation

    PubMed Central

    Kluckova, K; Sticha, M; Cerny, J; Mracek, T; Dong, L; Drahota, Z; Gottlieb, E; Neuzil, J; Rohlena, J

    2015-01-01

    Respiratory complex II (CII, succinate dehydrogenase, SDH) inhibition can induce cell death, but the mechanistic details need clarification. To elucidate the role of reactive oxygen species (ROS) formation upon the ubiquinone-binding (Qp) site blockade, we substituted CII subunit C (SDHC) residues lining the Qp site by site-directed mutagenesis. Cell lines carrying these mutations were characterized on the bases of CII activity and exposed to Qp site inhibitors MitoVES, thenoyltrifluoroacetone (TTFA) and Atpenin A5. We found that I56F and S68A SDHC variants, which support succinate-mediated respiration and maintain low intracellular succinate, were less efficiently inhibited by MitoVES than the wild-type (WT) variant. Importantly, associated ROS generation and cell death induction was also impaired, and cell death in the WT cells was malonate and catalase sensitive. In contrast, the S68A variant was much more susceptible to TTFA inhibition than the I56F variant or the WT CII, which was again reflected by enhanced ROS formation and increased malonate- and catalase-sensitive cell death induction. The R72C variant that accumulates intracellular succinate due to compromised CII activity was resistant to MitoVES and TTFA treatment and did not increase ROS, even though TTFA efficiently generated ROS at low succinate in mitochondria isolated from R72C cells. Similarly, the high-affinity Qp site inhibitor Atpenin A5 rapidly increased intracellular succinate in WT cells but did not induce ROS or cell death, unlike MitoVES and TTFA that upregulated succinate only moderately. These results demonstrate that cell death initiation upon CII inhibition depends on ROS and that the extent of cell death correlates with the potency of inhibition at the Qp site unless intracellular succinate is high. In addition, this validates the Qp site of CII as a target for cell death induction with relevance to cancer therapy. PMID:25950479

  10. Allicin Induces Calcium and Mitochondrial Dysregulation Causing Necrotic Death in Leishmania

    PubMed Central

    Corral, María J.; Benito-Peña, Elena; Jiménez-Antón, M. Dolores; Cuevas, Laureano; Moreno-Bondi, María C.; Alunda, José M.

    2016-01-01

    Background Allicin has shown antileishmanial activity in vitro and in vivo. However the mechanism of action underlying its antiproliferative effect against Leishmania has been virtually unexplored. In this paper, we present the results obtained in L.infantum and a mechanistic basis is proposed. Methodology/Principal Finding Exposure of the parasites to allicin led to high Ca2+ levels and mitochondrial reactive oxygen species (ROS), collapse of the mitochondrial membrane potential, reduced production of ATP and elevation of cytosolic ROS. The incubation of the promastigotes with SYTOX Green revealed that decrease of ATP was not associated with plasma membrane permeabilization. Annexin V and propidium iodide (PI) staining indicated that allicin did not induce phospholipids exposure on the plasma membrane. Moreover, DNA agarose gel electrophoresis and TUNEL analysis demonstrated that allicin did not provoke DNA fragmentation. Analysis of the cell cycle with PI staining showed that allicin induced cell cycle arrest in the G2/M phase. Conclusions/Significance We conclude that allicin induces dysregulation of calcium homeostasis and oxidative stress, uncontrolled by the antioxidant defense of the cell, which leads to mitochondrial dysfunction and a bioenergetic catastrophe leading to cell necrosis and cell cycle arrest in the premitotic phase. PMID:27023069

  11. Protective efficacy of mitochondrial targeted antioxidant MitoQ against dichlorvos induced oxidative stress and cell death in rat brain.

    PubMed

    Wani, Willayat Yousuf; Gudup, Satish; Sunkaria, Aditya; Bal, Amanjit; Singh, Parvinder Pal; Kandimalla, Ramesh J L; Sharma, Deep Raj; Gill, Kiran Dip

    2011-12-01

    Dichlorvos is a synthetic insecticide that belongs to the family of chemically related organophosphate (OP) pesticides. It can be released into the environment as a major degradation product of other OPs, such as trichlorfon, naled, and metrifonate. Dichlorvos exerts its toxic effects in humans and animals by inhibiting neural acetylcholinesterase. Chronic low-level exposure to dichlorvos has been shown to result in inhibition of the mitochondrial complex I and cytochrome oxidase in rat brain, resulting in generation of reactive oxygen species (ROS). Enhanced ROS production leads to disruption of cellular antioxidant defense systems and release of cytochrome c (cyt c) from mitochondria to cytosol resulting in apoptotic cell death. MitoQ is an antioxidant, selectively targeted to mitochondria and protects it from oxidative damage and has been shown to decrease mitochondrial damage in various animal models of oxidative stress. We hypothesized that if oxidative damage to mitochondria does play a significant role in dichlorvos induced neurodegeneration, then MitoQ should ameliorate neuronal apoptosis. Administration of MitoQ (100 μmol/kg body wt/day) reduced dichlorvos (6 mg/kg body wt/day) induced oxidative stress (decreased ROS production, increased MnSOD activity and glutathione levels) with decreased lipid peroxidation, protein and DNA oxidation. In addition, MitoQ also suppressed DNA fragmentation, cyt c release and caspase-3 activity in dichlorvos treated rats compared to the control group. Further electron microscopic studies revealed that MitoQ attenuates dichlorvos induced mitochondrial swelling, loss of cristae and chromatin condensation. These results indicate that MitoQ may be beneficial against OP (dichlorvos) induced neurodegeneration. PMID:21784090

  12. Mitochondrial complex I deficiency leads to inflammation and retinal ganglion cell death in the Ndufs4 mouse

    PubMed Central

    Yu, Alfred K.; Song, Lanying; Murray, Karl D.; van der List, Deborah; Sun, Chao; Shen, Yan; Xia, Zhengui; Cortopassi, Gino A.

    2015-01-01

    Mitochondrial complex I (NADH dehydrogenase) is a major contributor to neuronal energetics, and mutations in complex I lead to vision loss. Functional, neuroanatomical and transcriptional consequences of complex I deficiency were investigated in retinas of the Ndufs4 knockout mouse. Whole-eye ERGs and multielectrode arrays confirmed a major retinal ganglion cell functional loss at P32, and retinal ganglion cell loss at P42. RNAseq demonstrated a mild and then sharp increase in innate immune and inflammatory retinal transcripts at P22 and P33, respectively, which were confirmed with QRT-PCR. Intraperitoneal injection of the inflammogen lipopolysaccharide further reduced retinal ganglion cell function in Ndufs4 KO, supporting the connection between inflammatory activation and functional loss. Complex I deficiency in the retina clearly caused innate immune and inflammatory markers to increase coincident with loss of vision, and RGC functional loss. How complex I incites inflammation and functional loss is not clear, but could be the result of misfolded complex I generating a ‘non-self’ response, and induction of innate immune response transcripts was observed before functional loss at P22, including β-2 microglobulin and Cx3cr1, and during vision loss at P31 (B2m, Tlr 2, 3, 4, C1qa, Cx3cr1 and Fas). These data support the hypothesis that mitochondrial complex I dysfunction in the retina triggers an innate immune and inflammatory response that results in loss of retinal ganglion cell function and death, as in Leber's hereditary Optic Neuropathy and suggests novel therapeutic routes to counter mitochondrial defects that contribute to vision loss. PMID:25652399

  13. Calcium and reactive oxygen species in regulation of the mitochondrial permeability transition and of programmed cell death in yeast.

    PubMed

    Carraro, Michela; Bernardi, Paolo

    2016-08-01

    Mitochondria-dependent programmed cell death (PCD) in yeast shares many features with the intrinsic apoptotic pathway of mammals. With many stimuli, increased cytosolic [Ca(2+)] and ROS generation are the triggering signals that lead to mitochondrial permeabilization and release of proapoptotic factors, which initiates yeast PCD. While in mammals the permeability transition pore (PTP), a high-conductance inner membrane channel activated by increased matrix Ca(2+) and oxidative stress, is recognized as part of this signaling cascade, whether a similar process occurs in yeast is still debated. The potential role of the PTP in yeast PCD has generally been overlooked because yeast mitochondria lack the Ca(2+) uniporter, which in mammals allows rapid equilibration of cytosolic Ca(2+) with the matrix. In this short review we discuss the nature of the yeast permeability transition and reevaluate its potential role in the effector phase of yeast PCD triggered by Ca(2+) and oxidative stress. PMID:26995056

  14. TRPV1 mediates cell death in rat synovial fibroblasts through calcium entry-dependent ROS production and mitochondrial depolarization

    SciTech Connect

    Hu Fen; Sun Wenwu; Zhao Xiao Ting; Cui Zongjie Yang Wenxiu

    2008-05-16

    Synoviocyte hyperplasia is critical for rheumatoid arthritis, therefore, potentially an important target for therapeutics. It was found in this work that a TRPV1 agonist capsaicin, and acidic solution (pH 5.5) induced increases in cytosolic calcium concentration ([Ca{sup 2+}]{sub c}) and reactive oxygen species (ROS) production in synoviocytes isolated from a rat model of collagen-induced arthritis. The increases in both [Ca{sup 2+}]{sub c} and ROS production were completely abolished in calcium-free buffer or by a TRPV1 antagonist capsazepine. Further experiments revealed that capsaicin and pH 5.5 solution caused mitochondrial membrane depolarization and reduction in cell viability; such effects were inhibited by capsazepine, or the NAD(P)H oxidase inhibitor diphenylene iodonium. Both capsaicin and pH 5.5 buffer induced apoptosis as shown by nuclear condensation and fragmentation. Furthermore, RT-PCR readily detected TRPV1 mRNA expression in the isolated synoviocytes. Taken together, these data indicated that TRPV1 activation triggered synoviocyte death by [Ca{sup 2+}]{sub c} elevation, ROS production, and mitochondrial membrane depolarization.

  15. Arbitrariness and the death penalty: how the defendant's appearance during trial influences capital jurors' punishment decision.

    PubMed

    Antonio, Michael E

    2006-01-01

    This paper examines the impact of the defendant's appearance during the trial on capital jurors' punishment decision. The data used in this analysis were gathered by the Capital Jury Project (CJP), a national program of research on the decision-making of capital jurors. A series of multivariate logistic regression analyses were conducted using four aggravating circumstances related to the killing and eight defendant appearance variables as predictors of jurors' punishment decision at three points during the capital trial: (1) after the punishment phase ended, but before formal deliberation began; (2) when the first vote was taken on punishment at jury deliberations; and (3) at the final vote on punishment. Results indicated that when the defendant appeared emotionally involved during the trial (i.e. sorry and sincere) jurors either favored a life sentence or were undecided about punishment; however, when the defendant appeared emotionally uninvolved during the trial (i.e. bored) jurors either sought a death sentence or remained undecided. Policy implications will be discussed.

  16. Knockdown of TWIST1 enhances arsenic trioxide- and ionizing radiation-induced cell death in lung cancer cells by promoting mitochondrial dysfunction

    SciTech Connect

    Seo, Sung-Keum; Kim, Jae-Hee; Choi, Ha-Na; Choe, Tae-Boo; Hong, Seok-Il; Yi, Jae-Youn; Hwang, Sang-Gu; Lee, Hyun-Gyu; Lee, Yun-Han; Park, In-Chul

    2014-07-11

    Highlights: • Knockdown of TWIST1 enhanced ATO- and IR-induced cell death in NSCLCs. • Intracellular ROS levels were increased in cells treated with TWIST1 siRNA. • TWIST1 siRNA induced MMP loss and mitochondrial fragmentation. • TWIST1 siRNA upregulated the fission-related proteins FIS1 and DRP1. - Abstract: TWIST1 is implicated in the process of epithelial mesenchymal transition, metastasis, stemness, and drug resistance in cancer cells, and therefore is a potential target for cancer therapy. In the present study, we found that knockdown of TWIST1 by small interfering RNA (siRNA) enhanced arsenic trioxide (ATO)- and ionizing radiation (IR)-induced cell death in non-small-cell lung cancer cells. Interestingly, intracellular reactive oxygen species levels were increased in cells treated with TWIST1 siRNA and further increased by co-treatment with ATO or IR. Pretreatment of lung cancer cells with the antioxidant N-acetyl-cysteine markedly suppressed the cell death induced by combined treatment with TWIST1 siRNA and ATO or IR. Moreover, treatment of cells with TWIST1 siRNA induced mitochondrial membrane depolarization and significantly increased mitochondrial fragmentation (fission) and upregulated the fission-related proteins FIS1 and DRP1. Collectively, our results demonstrate that siRNA-mediated TWIST1 knockdown induces mitochondrial dysfunction and enhances IR- and ATO-induced cell death in lung cancer cells.

  17. TRIM4; a novel mitochondrial interacting RING E3 ligase, sensitizes the cells to hydrogen peroxide (H2O2) induced cell death.

    PubMed

    Tomar, Dhanendra; Prajapati, Paresh; Lavie, Julie; Singh, Kritarth; Lakshmi, Sripada; Bhatelia, Khyati; Roy, Milton; Singh, Rochika; Bénard, Giovanni; Singh, Rajesh

    2015-12-01

    The emerging evidences suggest that posttranslational modification of target protein by ubiquitin (Ub) not only regulate its turnover through ubiquitin proteasome system (UPS) but is a critical regulator of various signaling pathways. During ubiquitination, E3 ligase recognizes the target protein and determines the topology of ubiquitin chains. In current study, we studied the role of TRIM4, a member of the TRIM/RBCC protein family of RING E3 ligase, in regulation of hydrogen peroxide (H2O2) induced cell death. TRIM4 is expressed differentially in human tissues and expressed in most of the analyzed human cancer cell lines. The subcellular localization studies showed that TRIM4 forms distinct cytoplasmic speckle like structures which transiently interacts with mitochondria. The expression of TRIM4 induces mitochondrial aggregation and increased level of mitochondrial ROS in the presence of H2O2. It sensitizes the cells to H2O2 induced death whereas knockdown reversed the effect. TRIM4 potentiates the loss of mitochondrial transmembrane potential and cytochrome c release in the presence of H2O2. The analysis of TRIM4 interacting proteins showed its interaction with peroxiredoxin 1 (PRX1), including other proteins involved in regulation of mitochondrial and redox homeostasis. TRIM4 interaction with PRX1 is critical for the regulation of H2O2 induced cell death. Collectively, the evidences in the current study suggest the role of TRIM4 in regulation of oxidative stress induced cell death.

  18. Redox regulation of mitochondrial fission, protein misfolding, synaptic damage, and neuronal cell death: potential implications for Alzheimer’s and Parkinson’s diseases

    PubMed Central

    Nakamura, Tomohiro

    2010-01-01

    Normal mitochondrial dynamics consist of fission and fusion events giving rise to new mitochondria, a process termed mitochondrial biogenesis. However, several neurodegenerative disorders manifest aberrant mitochondrial dynamics, resulting in morphological abnormalities often associated with deficits in mitochondrial mobility and cell bioenergetics. Rarely, dysfunctional mitochondrial occur in a familial pattern due to genetic mutations, but much more commonly patients manifest sporadic forms of mitochondrial disability presumably related to a complex set of interactions of multiple genes (or their products) with environmental factors (G × E). Recent studies have shown that generation of excessive nitric oxide (NO), in part due to generation of oligomers of amyloid-β (Aβ) protein or overactivity of the NMDA-subtype of glutamate receptor, can augment mitochondrial fission, leading to frank fragmentation of the mitochondria. S-Nitrosylation, a covalent redox reaction of NO with specific protein thiol groups, represents one mechanism contributing to NO-induced mitochondrial fragmentation, bioenergetic failure, synaptic damage, and eventually neuronal apoptosis. Here, we summarize our evidence in Alzheimer’s disease (AD) patients and animal models showing that NO contributes to mitochondrial fragmentation via S-nitrosylation of dynamin-related protein 1 (Drp1), a protein involved in mitochondrial fission. These findings may provide a new target for drug development in AD. Additionally, we review emerging evidence that redox reactions triggered by excessive levels of NO can contribute to protein misfolding, the hallmark of a number of neurodegenerative disorders, including AD and Parkinson’s disease. For example, S-nitrosylation of parkin disrupts its E3 ubiquitin ligase activity, and thereby affects Lewy body formation and neuronal cell death. PMID:20177970

  19. In Vivo Mitochondrial p53 Translocation Triggers a Rapid First Wave of Cell Death in Response to DNA Damage That Can Precede p53 Target Gene Activation

    PubMed Central

    Erster, Susan; Mihara, Motohiro; Kim, Roger H.; Petrenko, Oleksi; Moll, Ute M.

    2004-01-01

    p53 promotes apoptosis in response to death stimuli by transactivation of target genes and by transcription-independent mechanisms. We recently showed that wild-type p53 rapidly translocates to mitochondria in response to multiple death stimuli in cultured cells. Mitochondrial p53 physically interacts with antiapoptotic Bcl proteins, induces Bak oligomerization, permeabilizes mitochondrial membranes, and rapidly induces cytochrome c release. Here we characterize the mitochondrial p53 response in vivo. Mice were subjected to γ irradiation or intravenous etoposide administration, followed by cell fractionation and immunofluorescence studies of various organs. Mitochondrial p53 accumulation occurred in radiosensitive organs like thymus, spleen, testis, and brain but not in liver and kidney. Of note, mitochondrial p53 translocation was rapid (detectable at 30 min in thymus and spleen) and triggered an early wave of marked caspase 3 activation and apoptosis. This caspase 3-mediated apoptosis was entirely p53 dependent, as shown by p53 null mice, and preceded p53 target gene activation. The transcriptional p53 program had a longer lag phase than the rapid mitochondrial p53 program. In thymus, the earliest apoptotic target gene products PUMA, Noxa, and Bax appeared at 2, 4, and 8 h, respectively, while Bid, Killer/DR5, and p53DinP1 remained uninduced even after 20 h. Target gene induction then led to further increase in active caspase 3. Similar biphasic kinetics was seen in cultured human cells. Our results suggest that in sensitive organs mitochondrial p53 accumulation in vivo occurs soon after a death stimulus, triggering a rapid first wave of apoptosis that is transcription independent and may precede a second slower wave that is transcription dependent. PMID:15254240

  20. Mitochondrial division inhibitor 1 (Mdivi-1) offers neuroprotection through diminishing cell death and improving functional outcome in a mouse model of traumatic brain injury.

    PubMed

    Wu, Qiong; Xia, Shui-Xiu; Li, Qian-Qian; Gao, Yuan; Shen, Xi; Ma, Lu; Zhang, Ming-Yang; Wang, Tao; Li, Yong-Sheng; Wang, Zu-Feng; Luo, Cheng-Liang; Tao, Lu-Yang

    2016-01-01

    Mitochondria dysfunction, an enormous potential crisis, has attracted increasing attention. Disturbed regulation of mitochondrial dynamics, the balance of mitochondrial fusion and fission, has been implicated in neurodegenerative diseases, such as Parkinson׳s disease and cerebral ischemia/reperfusion. However the role of mitochondrial dynamics in traumatic brain injury (TBI) has not been illuminated. The aim of the present study was to investigate the role of Mdivi-1, a small molecule inhibitor of a key mitochondrial fission protein dynamin-related protein 1 (Drp1), in TBI-induced cell death and functional outcome deficits. Protein expression of Drp1 was first investigated. Outcome parameters consist of motor test, Morris water maze, brain edema and lesion volume. Cell death was detected by propidium iodide (PI) labeling, and mitochondrial morphology was assessed using transmission electron microscopy. In addition, the expression of apoptosis-related proteins cytochrome c (cyt-c) and caspase-3 was investigated. Our findings showed that up-regulation of Drp1 expression started at 1h post-TBI and peaked at 24 h, but inhibition of Drp1 by Mdivi-1 significantly alleviated TBI-induced behavioral deficits and brain edema, reduced morphological change of mitochondria, and decreased TBI-induced cell death together with lesion volume. Moreover, treatment with Mdivi-1 remarkably inhibited TBI-induced the release of cyt-c from mitochondria to cytoplasm, and activation of caspase-3 at 24 h after TBI. Taken together, these data imply that inhibition of Drp1 may help attenuate TBI-induced functional outcome and cell death through maintaining normal mitochondrial morphology and inhibiting activation of apoptosis.

  1. Mitochondrial division inhibitor 1 (Mdivi-1) offers neuroprotection through diminishing cell death and improving functional outcome in a mouse model of traumatic brain injury.

    PubMed

    Wu, Qiong; Xia, Shui-Xiu; Li, Qian-Qian; Gao, Yuan; Shen, Xi; Ma, Lu; Zhang, Ming-Yang; Wang, Tao; Li, Yong-Sheng; Wang, Zu-Feng; Luo, Cheng-Liang; Tao, Lu-Yang

    2016-01-01

    Mitochondria dysfunction, an enormous potential crisis, has attracted increasing attention. Disturbed regulation of mitochondrial dynamics, the balance of mitochondrial fusion and fission, has been implicated in neurodegenerative diseases, such as Parkinson׳s disease and cerebral ischemia/reperfusion. However the role of mitochondrial dynamics in traumatic brain injury (TBI) has not been illuminated. The aim of the present study was to investigate the role of Mdivi-1, a small molecule inhibitor of a key mitochondrial fission protein dynamin-related protein 1 (Drp1), in TBI-induced cell death and functional outcome deficits. Protein expression of Drp1 was first investigated. Outcome parameters consist of motor test, Morris water maze, brain edema and lesion volume. Cell death was detected by propidium iodide (PI) labeling, and mitochondrial morphology was assessed using transmission electron microscopy. In addition, the expression of apoptosis-related proteins cytochrome c (cyt-c) and caspase-3 was investigated. Our findings showed that up-regulation of Drp1 expression started at 1h post-TBI and peaked at 24 h, but inhibition of Drp1 by Mdivi-1 significantly alleviated TBI-induced behavioral deficits and brain edema, reduced morphological change of mitochondria, and decreased TBI-induced cell death together with lesion volume. Moreover, treatment with Mdivi-1 remarkably inhibited TBI-induced the release of cyt-c from mitochondria to cytoplasm, and activation of caspase-3 at 24 h after TBI. Taken together, these data imply that inhibition of Drp1 may help attenuate TBI-induced functional outcome and cell death through maintaining normal mitochondrial morphology and inhibiting activation of apoptosis. PMID:26596858

  2. Estimation of age at death based on quantitation of the 4977-bp deletion of human mitochondrial DNA in skeletal muscle.

    PubMed

    Meissner, C; von Wurmb, N; Schimansky, B; Oehmichen, M

    1999-11-01

    The 4977-bp deletion in human mitochondrial DNA (mtDNA) is known to accumulate in various tissues with age. Since this deletion in mtDNA correlates closest with age in muscle tissue, iliopsoas muscle tissue was taken at autopsy from 50 persons aged 24-97 years to determine whether age at death can be estimated based on the amount of the 4977-bp deletion in skeletal muscle. Total DNA (nuclear and mtDNA) was extracted from 100 mg tissue and the 4977-bp deletion quantified using a kinetic polymerase chain reaction (PCR) followed by visualization of the products on silver stained polyacrylamide gels. The amount of the 4977-bp deletion of mtDNA ranged from 0.00049% to 0.14% depending on age, with a correlation coefficient of r = 0.83 (P = 0.0001). In forensic practice this method can aid in the estimation of age at death with a relatively wide confidence interval, thus enabling a discrimination between young and elderly persons in the identification of human remains based solely on skeletal muscle.

  3. The involvement of mitochondrial apoptotic pathway in eugenol-induced cell death in human glioblastoma cells.

    PubMed

    Liang, Wei-Zhe; Chou, Chiang-Ting; Hsu, Shu-Shong; Liao, Wei-Chuan; Shieh, Pochuen; Kuo, Daih-Huang; Tseng, Hui-Wen; Kuo, Chun-Chi; Jan, Chung-Ren

    2015-01-01

    Eugenol, a natural phenolic constituent of clove oil, has a wide range of applications in medicine as a local antiseptic and anesthetic. However, the effect of eugenol on human glioblastoma is unclear. This study examined whether eugenol elevated intracellular free Ca(2+) levels ([Ca(2+)]i) and induced apoptosis in DBTRG-05MG human glioblastoma cells. Eugenol evoked [Ca(2+)]i rises which were reduced by removing extracellular Ca(2+). Eugenol-induced [Ca(2+)]i rises were not altered by store-operated Ca(2+) channel blockers but were inhibited by the PKC inhibitor GF109203X and the transient receptor potential channel melastatin 8 (TRPM8) antagonist capsazepine. In Ca(2+)-free medium, pretreatment with the endoplasmic reticulum Ca(2+) pump inhibitor thapsigargin (TG) or 2,5-di-tert-butylhydroquinone (BHQ) abolished eugenol-induced [Ca(2+)]i rises. The phospholipase C (PLC) inhibitor U73122 significantly inhibited eugenol-induced [Ca(2+)]i rises. Eugenol killed cells which were not reversed by prechelating cytosolic Ca(2+) with 1,2-bis(2-aminophenoxy) ethane-N,N,N',N'-tetraacetic acid-acetoxymethyl ester (BAPTA-AM). Eugenol induced apoptosis through increasing reactive oxygen species (ROS) production, decreasing mitochondrial membrane potential, releasing cytochrome c and activating caspase-9/caspase-3. Together, in DBTRG-05MG cells, eugenol evoked [Ca(2+)]i rises by inducing PLC-dependent release of Ca(2+) from the endoplasmic reticulum and caused Ca(2+) influx possibly through TRPM8 or PKC-sensitive channels. Furthermore, eugenol induced the mitochondrial apoptotic pathway. PMID:25455450

  4. Thiosemicarbazone p-Substituted Acetophenone Derivatives Promote the Loss of Mitochondrial Δψ, GSH Depletion, and Death in K562 Cells

    PubMed Central

    Pessoto, Felipe S.; Yokomizo, Cesar H.; Prieto, Tatiana; Fernandes, Cleverton S.; Silva, Alan P.; Kaiser, Carlos R.; Basso, Ernani A.; Nantes, Iseli L.

    2015-01-01

    A series of thiosemicarbazone (TSC) p-substituted acetophenone derivatives were synthesized and chemically characterized. The p-substituents appended to the phenyl group of the TSC structures were hydrogen, fluor, chlorine, methyl, and nitro, producing compounds named TSC-H, TSC-F, TSC-Cl, TSC-Me, and TSC-NO2, respectively. The TSC compounds were evaluated for their capacity to induce mitochondrial permeability, to deplete mitochondrial thiol content, and to promote cell death in the K562 cell lineage using flow cytometry and fluorescence microscopy. TSC-H, TSC-F, and TSC-Cl exhibited a bell-shaped dose-response curve for the induction of apoptosis in K562 cells due to the change from apoptosis to necrosis as the principal mechanism of cell death at the highest tested doses. TSC-Me and TSC-NO2 exhibited a typical dose-response profile, with a half maximal effective concentration of approximately 10 µM for cell death. Cell death was also evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, which revealed lower toxicity of these compounds for peripheral blood mononuclear cells than for K562 cells. The possible mechanisms leading to cell death are discussed based on the observed effects of the new TSC compounds on the cellular thiol content and on mitochondrial bioenergetics. PMID:26075034

  5. Thiosemicarbazone p-Substituted Acetophenone Derivatives Promote the Loss of Mitochondrial Δψ, GSH Depletion, and Death in K562 Cells.

    PubMed

    Pessoto, Felipe S; Yokomizo, Cesar H; Prieto, Tatiana; Fernandes, Cleverton S; Silva, Alan P; Kaiser, Carlos R; Basso, Ernani A; Nantes, Iseli L

    2015-01-01

    A series of thiosemicarbazone (TSC) p-substituted acetophenone derivatives were synthesized and chemically characterized. The p-substituents appended to the phenyl group of the TSC structures were hydrogen, fluor, chlorine, methyl, and nitro, producing compounds named TSC-H, TSC-F, TSC-Cl, TSC-Me, and TSC-NO2, respectively. The TSC compounds were evaluated for their capacity to induce mitochondrial permeability, to deplete mitochondrial thiol content, and to promote cell death in the K562 cell lineage using flow cytometry and fluorescence microscopy. TSC-H, TSC-F, and TSC-Cl exhibited a bell-shaped dose-response curve for the induction of apoptosis in K562 cells due to the change from apoptosis to necrosis as the principal mechanism of cell death at the highest tested doses. TSC-Me and TSC-NO2 exhibited a typical dose-response profile, with a half maximal effective concentration of approximately 10 µM for cell death. Cell death was also evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, which revealed lower toxicity of these compounds for peripheral blood mononuclear cells than for K562 cells. The possible mechanisms leading to cell death are discussed based on the observed effects of the new TSC compounds on the cellular thiol content and on mitochondrial bioenergetics. PMID:26075034

  6. Mitochondrial E3 Ubiquitin Protein Ligase 1 Mediates Cigarette Smoke-Induced Endothelial Cell Death and Dysfunction.

    PubMed

    Kim, Sun-Yong; Kim, Hyo Jeong; Park, Mi Kyeong; Huh, Jin Won; Park, Hye Yun; Ha, Sang Yun; Shin, Joo-Ho; Lee, Yun-Song

    2016-02-01

    By virtue of the critical roles of Akt in vascular endothelial cell (EC) survival and function, cigarette smoke-induced Akt reduction may contribute to EC death and dysfunction in smokers' lungs. One of the negative Akt regulatory mechanisms is K48-linked Akt ubiquitination and subsequent proteasomal degradation. Here, we assessed the involvement of mitochondrial E3 ubiquitin protein ligase 1 (MUL1), recently revealed as a novel Akt ubiquitin E3 ligase, in cigarette smoke-induced Akt ubiquitination and its contribution to pulmonary EC death and dysfunction. In human lung microvascular ECs (HLMVECs), cigarette smoke extract (CSE) noticeably elevated MUL1 expression and K48-linked Akt ubiquitination, whereas Akt, p-Akt, eNOS, and p-eNOS levels were decreased. MUL1 knockdown suppressed CSE-induced Akt ubiquitination/degradation and cytoplasmic reductions of Akt and p-Akt. Furthermore, MUL1 knockdown attenuated reductions of eNOS and p-eNOS and alleviated EC survival, migration, and tube formation in the presence of CSE exposure. In addition, overexpression of K284R Akt, a mutant for a MUL1-ubiquitination site, produced similar effects. In HLMVECs exposed to CSE, Akt-MUL1 interaction was increased in coimmunoprecipitation and in situ proximity ligation assays. Similarly, the proximity ligation assay signals were elevated in rat lungs exposed to cigarette smoke for 3 months, during which Mul1 levels were noticeably increased. Finally, we found that CSE-mediated MUL1 induction in HLMVECs is mediated by retinoic acid receptor-related orphan receptor α. Taken together, these data suggest that cigarette smoke-induced MUL1 elevation mediates Akt ubiquitination/degradation, potentially leading to pulmonary EC death and functional impairment.

  7. Regulation of the Transcription Factor EB-PGC1α Axis by Beclin-1 Controls Mitochondrial Quality and Cardiomyocyte Death under Stress

    PubMed Central

    Ma, Xiucui; Liu, Haiyan; Murphy, John T.; Foyil, Sarah R.; Godar, Rebecca J.; Abuirqeba, Haedar; Weinheimer, Carla J.; Barger, Philip M.

    2015-01-01

    In cardiac ischemia-reperfusion injury, reactive oxygen species (ROS) generation and upregulation of the hypoxia-inducible protein BNIP3 result in mitochondrial permeabilization, but impairment in autophagic removal of damaged mitochondria provokes programmed cardiomyocyte death. BNIP3 expression and ROS generation result in upregulation of beclin-1, a protein associated with transcriptional suppression of autophagy-lysosome proteins and reduced activation of transcription factor EB (TFEB), a master regulator of the autophagy-lysosome machinery. Partial beclin-1 knockdown transcriptionally stimulates lysosome biogenesis and autophagy via mTOR inhibition and activation of TFEB, enhancing removal of depolarized mitochondria. TFEB activation concomitantly stimulates mitochondrial biogenesis via PGC1α induction to restore normally polarized mitochondria and attenuate BNIP3- and hypoxia-reoxygenation-induced cell death. Conversely, overexpression of beclin-1 activates mTOR to inhibit TFEB, resulting in declines in lysosome numbers and suppression of PGC1α transcription. Importantly, knockdown of endogenous TFEB or PGC1α results in a complete or partial loss, respectively, of the cytoprotective effects of partial beclin-1 knockdown, indicating a critical role for both mitochondrial autophagy and biogenesis in ensuring cellular viability. These studies uncover a transcriptional feedback loop for beclin-1-mediated regulation of TFEB activation and implicate a central role for TFEB in coordinating mitochondrial autophagy with biogenesis to restore normally polarized mitochondria and prevent ischemia-reperfusion-induced cardiomyocyte death. PMID:25561470

  8. Arsenic-induced mitochondrial instability leading to programmed cell death in the exposed individuals.

    PubMed

    Banerjee, Nilanjana; Banerjee, Mayukh; Ganguly, Sudipto; Bandyopadhyay, Santu; Das, Jayanta K; Bandyopadhay, Apurba; Chatterjee, Mitali; Giri, Ashok K

    2008-04-18

    In West Bengal, India, more than 6 million people in nine districts are exposed to arsenic through drinking water. It is regarded as the greatest arsenic calamity in the world. Arsenic is a well-documented human carcinogen, which does not induce cancer in any other animal model. Interestingly, at lower concentrations, arsenic is known to induce apoptosis in various cancer cell lines in vitro. We have studied apoptosis in human peripheral blood mononuclear cells (PBMC) of 30 arsenic exposed skin lesion individuals by annexin V-FITC staining and compared with 28 unexposed individuals. The percentage of apoptotic cells in individuals with skin lesions was significantly higher (p<0.001) in comparison to unexposed individuals. In the exposed individuals with skin lesions, there were elevated levels of intracellular reactive oxygen species (ROS), mitochondrial membrane permeability and increased cytochrome c release, leading to increased downstream caspase activity. Arsenic-induced DNA damage was confirmed by DNA ladder formation and confocal microscopy. We also observed that chronic arsenic exposure reduced Bcl-2/Bax ratio and also resulted in cell cycle arrest of PBMC in G0/G1 phase. All these observations indicate that mitochondria-mediated pathway may be responsible for arsenic-induced apoptosis.

  9. Cell Death and Survival Through the Endoplasmic Reticulum-Mitochondrial Axis

    PubMed Central

    Bravo-Sagua, R.; Rodriguez, A.E.; Kuzmicic, J.; Gutierrez, T.; Lopez-Crisosto, C.; Quiroga, C.; Díaz-Elizondo, J.; Chiong, M.; Gillette, T.G.; Rothermel, B.A.; Lavandero, S.

    2014-01-01

    The endoplasmic reticulum has a central role in biosynthesis of a variety of proteins and lipids. Mitochondria generate ATP, synthesize and process numerous metabolites, and are key regulators of cell death. The architectures of endoplasmic reticulum and mitochondria change continually via the process of membrane fusion, fission, elongation, degradation, and renewal. These structural changes correlate with important changes in organellar function. Both organelles are capable of moving along the cytoskeleton, thus changing their cellular distribution. Numerous studies have demonstrated coordination and communication between mitochondria and endoplasmic reticulum. A focal point for these interactions is a zone of close contact between them known as the mitochondrial–associated endoplasmic reticulum membrane (MAM), which serves as a signaling juncture that facilitates calcium and lipid transfer between organelles. Here we review the emerging data on how communication between endoplasmic reticulum and mitochondria can modulate organelle function and determine cellular fate. PMID:23228132

  10. Mitochondrial physiology and pathology; concepts of programmed death of organelles, cells and organisms.

    PubMed

    Skulachev, V P

    1999-06-01

    The review summarizes the present state of our knowledge concerning alternative functions of mitochondria, namely energy conservation in forms of protonic potential and ATP, thermoregulatory energy dissipation as heat, production of useful substances, decomposition of harmful substances, control of cellular processes. The recent progress in understanding of some mitochondrion-linked pathologies is described. The role of reactive oxygen species in these processes is stressed. Possible mechanisms of programmed death of mitochondrion (mitoptosis), cell (apoptosis) and organism (phenoptosis) are considered. A concept is put forward assuming that mitoptosis is involved in some types of apoptosis whereas apoptosis can be a part of a phenoptotic cascade. It is hypothesized that septic shock, as well as the stress-induced brain and heart ischemic diseases and cancer, exemplify mechanisms of phenoptosis purifying population, community of organisms or kin from dangerous or useless individuals. PMID:10626278

  11. Emodin induces apoptosis of human cervical cancer hela cells via intrinsic mitochondrial and extrinsic death receptor pathway

    PubMed Central

    2013-01-01

    Background Emodin is a natural anthraquinone derivative isolated from the Rheum palmatum L. Aim: The aim of the present study was to investigate the effect of emodin on the apoptosis of the human cervical cancer line HeLa and to identify the mechanisms involved. Methods Relative cell viability was assessed by MTT assay after treatment with emodin. Cell apoptosis was detected with TUNEL, Hoechst 33342 staining and quantified with flow cytometry using annexin FITC-PI staining. Results The percentage of apoptotic cells was 0.8, 8.2, 22.1, and 43.7%, respectively. The mRNA levels of Caspase-9, -8 and −3 detected by Real-time PCR after treatment with emodin were significantly increased. Emodin increased the protein levels of Cytochome c, Apaf-1, Fas, FasL, and FADD but decreased the protein levels of Pro-caspase-9, Pro-caspase-8 and Pro-caspase-3. Conclusion We conclude that the emodin inhibited HeLa proliferation by inducing apoptosis through the intrinsic mitochondrial and extrinsic death receptor pathways. PMID:23866157

  12. Mitochondrial targets of photodynamic therapy and their contribution to cell death

    NASA Astrophysics Data System (ADS)

    Oleinick, Nancy L.; Usuda, Jitsuo; Xue, Liang-yan; Azizuddin, Kashif; Chiu, Song-mao; Lam, Minh C.; Morris, Rachel L.; Nieminen, Anna-Liisa

    2002-06-01

    In response to photodynamic therapy (PDT), many cells in culture or within experimental tumors are eliminated by apoptosis. PDT with photosensitizers that localize in or target mitochondria, such as the phthalocyanine Pc 4, causes prompt release of cytochrome c into the cytoplasm and activation of caspases-9 and -3, among other caspases, that are responsible for initiating cell degradation. Some cells appear resistant to apoptosis after PDT; however, if they have sustained sufficient damage, they will die by a necrotic process or through a different apoptotic pathway. In the case of PDT, the distinction between apoptosis and necrosis may be less important than the mechanism that triggers both processes, since critical lethal damage appears to occur during treatment and does not require the major steps in apoptosis to be expressed. We earlier showed, for example, that human breast cancer MCF-7 cells that lack caspase-3 are resistant to the induction of apoptosis by PDT, but are just as sensitive to the loss of clonogenicity as MCF-7 cells stably expressing transfected procaspase-3. Many photosensitizers that target mitochondria specifically attack the anti-apoptotic protein Bcl-2, generating a variety of crosslinked and cleaved photoproducts. Recent evidence suggests that the closely related protein Bcl-xL is also a target of Pc 4-PDT. Transient transfection of an expression vector encoding deletion mutants of Bcl-2 have identified the critical sensitive site in the protein that is required for photodamage. This region contains two alpha helices that form a secondary membrane anchorage site and are thought to be responsible for pore formation by Bcl-2. As specific protein targets are identified, we are becoming better able to model the critical events in PDT-induced cell death.

  13. Death upon a kiss: mitochondrial outer membrane composition and organelle communication govern sensitivity to BAK/BAX-dependent apoptosis

    PubMed Central

    Renault, Thibaud T.; Chipuk, Jerry E.

    2013-01-01

    SUMMARY In order for stressed cells to induce the mitochondrial pathway of apoptosis, a cohort of pro-apoptotic BCL-2 proteins must collaborate with the outer mitochondrial membrane to permeabilize it. BAK and BAX are the two pro-apoptotic BCL-2 family members that are required for mitochondrial outer membrane permeabilization. While biochemical and structural insights of BAK/BAX function have expanded in the recent years, very little is known about the role of the outer mitochondrial membrane in regulating BAK/BAX activity. In this review, we will highlight the impact of mitochondrial composition (both protein and lipid), and mitochondrial interactions with cellular organelles, on BAK/BAX function and cellular commitment to apoptosis. A better understanding of how BAK/BAX and mitochondrial biology are mechanistically linked will likely reveal novel insights into homeostatic and pathological mechanisms associated with apoptosis. PMID:24269152

  14. The mitochondrial ATP-dependent Lon protease: a novel target in lymphoma death mediated by the synthetic triterpenoid CDDO and its derivatives

    PubMed Central

    Venkatesh, Sundararajan; Li, Min; Lee, Jae; Lu, Bin; Hilchey, Shannon P.; Morse, Kimberly M.; Metcalfe, Hollie M.; Skalska, Jolanta; Andreeff, Michael; Brookes, Paul S.

    2012-01-01

    Synthetic triterpenoids are multitarget compounds exhibiting promise as preventative and therapeutic agents for cancer. Their proposed mechanism of action is by forming Michael adducts with reactive nucleophilic groups on target proteins. Our previous work demonstrates that the 2-cyano-3,12-dioxooleana-1,9-dien-28-oic acid (CDDO) and its derivatives promote B-lymphoid cell apoptosis through a mitochondria-mediated pathway linked to mitochondrial protein aggregation. As one function of the Lon protease is to eliminate abnormal mitochondrial proteins, we hypothesized that CDDO-induced protein aggregation and lymphoma apoptosis occur by inactivating this enzyme. Here, we show that CDDO and its derivatives directly and selectively inhibit Lon. CDDO blocks Lon-mediated proteolysis in biochemical and cellular assays, but does not inhibit the 20S proteasome. Furthermore, a biotinylated-CDDO conjugate modifies mitochondrial Lon. A striking common phenotype of CDDO-treated lymphoma cells and Lon-knockdown cells is the accumulation of electron-dense aggregates within mitochondria. We also show that Lon protein levels are substantially elevated in malignant lymphoma cells, compared with resting or activated B cells. Finally, we demonstrate that Lon knockdown leads to lymphoma cell death. Together, these findings suggest that Lon inhibition plays a contributory role in CDDO-induced lymphoma cell death, and support the concept that mitochondrial Lon is a novel anticancer drug target. PMID:22323447

  15. The mitochondrial ATP-dependent Lon protease: a novel target in lymphoma death mediated by the synthetic triterpenoid CDDO and its derivatives.

    PubMed

    Bernstein, Steven H; Venkatesh, Sundararajan; Li, Min; Lee, Jae; Lu, Bin; Hilchey, Shannon P; Morse, Kimberly M; Metcalfe, Hollie M; Skalska, Jolanta; Andreeff, Michael; Brookes, Paul S; Suzuki, Carolyn K

    2012-04-01

    Synthetic triterpenoids are multitarget compounds exhibiting promise as preventative and therapeutic agents for cancer. Their proposed mechanism of action is by forming Michael adducts with reactive nucleophilic groups on target proteins. Our previous work demonstrates that the 2-cyano-3,12-dioxooleana-1,9-dien-28-oic acid (CDDO) and its derivatives promote B-lymphoid cell apoptosis through a mitochondria-mediated pathway linked to mitochondrial protein aggregation. As one function of the Lon protease is to eliminate abnormal mitochondrial proteins, we hypothesized that CDDO-induced protein aggregation and lymphoma apoptosis occur by inactivating this enzyme. Here, we show that CDDO and its derivatives directly and selectively inhibit Lon. CDDO blocks Lon-mediated proteolysis in biochemical and cellular assays, but does not inhibit the 20S proteasome. Furthermore, a biotinylated-CDDO conjugate modifies mitochondrial Lon. A striking common phenotype of CDDO-treated lymphoma cells and Lon-knockdown cells is the accumulation of electron-dense aggregates within mitochondria. We also show that Lon protein levels are substantially elevated in malignant lymphoma cells, compared with resting or activated B cells. Finally, we demonstrate that Lon knockdown leads to lymphoma cell death. Together, these findings suggest that Lon inhibition plays a contributory role in CDDO-induced lymphoma cell death, and support the concept that mitochondrial Lon is a novel anticancer drug target.

  16. Sudden adult death syndrome in m.3243A>G-related mitochondrial disease: an unrecognized clinical entity in young, asymptomatic adults

    PubMed Central

    Ng, Yi Shiau; Grady, John P.; Lax, Nichola Z.; Bourke, John P.; Alston, Charlotte L.; Hardy, Steven A.; Falkous, Gavin; Schaefer, Andrew G.; Radunovic, Aleksandar; Mohiddin, Saidi A.; Ralph, Matilda; Alhakim, Ali; Taylor, Robert W.; McFarland, Robert; Turnbull, Douglass M.; Gorman, Gráinne S.

    2016-01-01

    Aims To provide insight into the mechanism of sudden adult death syndrome (SADS) and to give new clinical guidelines for the cardiac management of patients with the most common mitochondrial DNA mutation, m.3243A>G. These studies were initiated after two young, asymptomatic adults harbouring the m.3243A>G mutation died suddenly and unexpectedly. The m.3243A>G mutation is present in ∼1 in 400 of the population, although the recognized incidence of mitochondrial DNA (mtDNA) disease is ∼1 in 5000. Methods and results Pathological studies including histochemistry and molecular genetic analyses performed on various post-mortem samples including cardiac tissues (atrium and ventricles) showed marked respiratory chain deficiency and high levels of the m.3243A>G mutation. Systematic review of cause of death in our m.3243A>G patient cohort showed the person-time incidence rate of sudden adult death is 2.4 per 1000 person-years. A further six cases of sudden death among extended family members have been identified from interrogation of family pedigrees. Conclusion Our findings suggest that SADS is an important cause of death in patients with m.3243A>G and likely to be due to widespread respiratory chain deficiency in cardiac muscle. The involvement of asymptomatic relatives highlights the importance of family tracing in patients with m.3243A>G and the need for specific cardiac arrhythmia surveillance in the management of this common genetic disease. In addition, these findings have prompted the derivation of cardiac guidelines specific to patients with m.3243A>G-related mitochondrial disease. Finally, due to the prevalence of this mtDNA point mutation, we recommend inclusion of testing for m.3243A>G mutations in the genetic autopsy of all unexplained cases of SADS. PMID:26188002

  17. Thymoquinone induces caspase-independent, autophagic cell death in CPT-11-resistant lovo colon cancer via mitochondrial dysfunction and activation of JNK and p38.

    PubMed

    Chen, Ming-Cheng; Lee, Nien-Hung; Hsu, Hsi-Hsien; Ho, Tsung-Jung; Tu, Chuan-Chou; Hsieh, Dennis Jine-Yuan; Lin, Yueh-Min; Chen, Li-Mien; Kuo, Wei-Wen; Huang, Chih-Yang

    2015-02-11

    Chemotherapy causes unwanted side effects and chemoresistance, limiting its effectiveness. Therefore, phytochemicals are now used as alternative treatments. Thymoquinone (TQ) is used to treat different cancers, including colon cancer. The irinotecan-resistant (CPT-11-R) LoVo colon cancer cell line was previously constructed by stepwise CPT-11 challenges to untreated parental LoVo cells. TQ dose-dependently increased the total cell death index and activated apoptosis at 2 μM, which then diminished at increasing doses. The possibility of autophagic cell death was then investigated. TQ caused mitochondrial outer membrane permeability (MOMP) and activated autophagic cell death. JNK and p38 inhibitors (SP600125 and SB203580, respectively) reversed TQ autophagic cell death. TQ was also found to activate apoptosis before autophagy, and the direction of cell death was switched toward autophagic cell death at initiation of autophagosome formation. Therefore, TQ resulted in caspase-independent, autophagic cell death via MOMP and activation of JNK and p38 in CPT-11-R LoVo colon cancer cells.

  18. Constitutive p53 heightens mitochondrial apoptotic priming and favors cell death induction by BH3 mimetic inhibitors of BCL-xL

    PubMed Central

    Le Pen, J; Laurent, M; Sarosiek, K; Vuillier, C; Gautier, F; Montessuit, S; Martinou, J C; Letaï, A; Braun, F; Juin, P P

    2016-01-01

    Proapoptotic molecules directly targeting the BCL-2 family network are promising anticancer therapeutics, but an understanding of the cellular stress signals that render them effective is still elusive. We show here that the tumor suppressor p53, at least in part by transcription independent mechanisms, contributes to cell death induction and full activation of BAX by BH3 mimetic inhibitors of BCL-xL. In addition to mildly facilitating the ability of compounds to derepress BAX from BCL-xL, p53 also provides a death signal downstream of anti-apoptotic proteins inhibition. This death signal cooperates with BH3-induced activation of BAX and it is independent from PUMA, as enhanced p53 can substitute for PUMA to promote BAX activation in response to BH3 mimetics. The acute sensitivity of mitochondrial priming to p53 revealed here is likely to be critical for the clinical use of BH3 mimetics. PMID:26844698

  19. Malonate induces cell death via mitochondrial potential collapse and delayed swelling through an ROS-dependent pathway

    PubMed Central

    Fernandez-Gomez, Francisco J; Galindo, Maria F; Gómez-Lázaro, Maria; Yuste, Victor J; Comella, Joan X; Aguirre, Norberto; Jordán, Joaquín

    2005-01-01

    Herein we study the effects of the mitochondrial complex II inhibitor malonate on its primary target, the mitochondrion. Malonate induces mitochondrial potential collapse, mitochondrial swelling, cytochrome c (Cyt c) release and depletes glutathione (GSH) and nicotinamide adenine dinucleotide coenzyme (NAD(P)H) stores in brain-isolated mitochondria. Although, mitochondrial potential collapse was almost immediate after malonate addition, mitochondrial swelling was not evident before 15 min of drug presence. This latter effect was blocked by cyclosporin A (CSA), Ruthenium Red (RR), magnesium, catalase, GSH and vitamin E. Malonate added to SH-SY5Y cell cultures produced a marked loss of cell viability together with the release of Cyt c and depletion of GSH and NAD(P)H concentrations. All these effects were not apparent in SH-SY5Y cells overexpressing Bcl-xL. When GSH concentrations were lowered with buthionine sulphoximine, cytoprotection afforded by Bcl-xL overexpression was not evident anymore. Taken together, all these data suggest that malonate causes a rapid mitochondrial potential collapse and reactive oxygen species production that overwhelms mitochondrial antioxidant capacity and leads to mitochondrial swelling. Further permeability transition pore opening and the subsequent release of proapoptotic factors such as Cyt c could therefore be, at least in part, responsible for malonate-induced toxicity. PMID:15655518

  20. Osteopontin-stimulated apoptosis in cardiac myocytes involves oxidative stress and mitochondrial death pathway: role of a pro-apoptotic protein BIK.

    PubMed

    Dalal, Suman; Zha, Qinqin; Singh, Mahipal; Singh, Krishna

    2016-07-01

    Increased osteopontin (OPN) expression in the heart, specifically in myocytes, associates with increased myocyte apoptosis and myocardial dysfunction. Recently, we provided evidence that OPN interacts with CD44 receptor, and induces myocyte apoptosis via the involvement of endoplasmic reticulum stress and mitochondrial death pathways. Here we tested the hypothesis that OPN induces oxidative stress in myocytes and the heart via the involvement of mitochondria and NADPH oxidase-4 (NOX-4). Treatment of adult rat ventricular myocytes (ARVMs) with OPN (20 nM) increased oxidative stress as analyzed by protein carbonylation, and intracellular reactive oxygen species (ROS) levels as analyzed by ROS detection kit and dichlorohydrofluorescein diacetate staining. Pretreatment with NAC (antioxidant), apocynin (NOX inhibitor), MnTBAP (superoxide dismutase mimetic), and mitochondrial KATP channel blockers (glibenclamide and 5-hydroxydecanoate) decreased OPN-stimulated ROS production, cytosolic cytochrome c levels, and apoptosis. OPN increased NOX-4 expression, while decreasing SOD-2 expression. OPN decreased mitochondrial membrane potential as measured by JC-1 staining, and induced mitochondrial abnormalities including swelling and reorganization of cristae as observed using transmission electron microscopy. OPN increased expression of BIK, a pro-apoptotic protein involved in reorganization of mitochondrial cristae. Expression of dominant-negative BIK decreased OPN-stimulated apoptosis. In vivo, OPN expression in cardiac myocyte-specific manner associated with increased protein carbonylation, and expression of NOX-4 and BIK. Thus, OPN induces oxidative stress via the involvement of mitochondria and NOX-4. It may affect mitochondrial morphology and integrity, at least in part, via the involvement of BIK. PMID:27262843

  1. DRP1-dependent apoptotic mitochondrial fission occurs independently of BAX, BAK and APAF1 to amplify cell death by BID and oxidative stress.

    PubMed

    Oettinghaus, Björn; D'Alonzo, Donato; Barbieri, Elisa; Restelli, Lisa Michelle; Savoia, Claudia; Licci, Maria; Tolnay, Markus; Frank, Stephan; Scorrano, Luca

    2016-08-01

    During apoptosis mitochondria undergo cristae remodeling and fragmentation, but how the latter relates to outer membrane permeabilization and downstream caspase activation is unclear. Here we show that the mitochondrial fission protein Dynamin Related Protein (Drp) 1 participates in cytochrome c release by selected intrinsic death stimuli. While Bax, Bak double deficient (DKO) and Apaf1(-/-) mouse embryonic fibroblasts (MEFs) were less susceptible to apoptosis by Bcl-2 family member BID, H(2)O(2), staurosporine and thapsigargin, Drp1(-/-) MEFs were protected only from BID and H(2)O(2). Resistance to cell death of Drp1(-/-) and DKO MEFs correlated with blunted cytochrome c release, whereas mitochondrial fragmentation occurred in all cell lines in response to all tested stimuli, indicating that other mechanisms accounted for the reduced cytochrome c release. Indeed, cristae remodeling was reduced in Drp1(-/-) cells, potentially explaining their resistance to apoptosis. Our results indicate that caspase-independent mitochondrial fission and Drp1-dependent cristae remodeling amplify apoptosis. This article is part of a Special Issue entitled 'EBEC 2016: 19th European Bioenergetics Conference, Riva del Garda, Italy, July 2-6, 2016', edited by Prof. Paolo Bernardi.

  2. PINK1 protects against cell death induced by mitochondrial depolarization, by phosphorylating Bcl-xL and impairing its pro-apoptotic cleavage

    PubMed Central

    Arena, G; Gelmetti, V; Torosantucci, L; Vignone, D; Lamorte, G; De Rosa, P; Cilia, E; Jonas, E A; Valente, E M

    2013-01-01

    Mutations in the PINK1 gene are a frequent cause of autosomal recessive Parkinson's disease (PD). PINK1 encodes a mitochondrial kinase with neuroprotective activity, implicated in maintaining mitochondrial homeostasis and function. In concurrence with Parkin, PINK1 regulates mitochondrial trafficking and degradation of damaged mitochondria through mitophagy. Moreover, PINK1 can activate autophagy by interacting with the pro-autophagic protein Beclin-1. Here, we report that, upon mitochondrial depolarization, PINK1 interacts with and phosphorylates Bcl-xL, an anti-apoptotic protein also known to inhibit autophagy through its binding to Beclin-1. PINK1–Bcl-xL interaction does not interfere either with Beclin-1 release from Bcl-xL or the mitophagy pathway; rather it protects against cell death by hindering the pro-apoptotic cleavage of Bcl-xL. Our data provide a functional link between PINK1, Bcl-xL and apoptosis, suggesting a novel mechanism through which PINK1 regulates cell survival. This pathway could be relevant for the pathogenesis of PD as well as other diseases including cancer. PMID:23519076

  3. Saving Can Save from Death Anxiety: Mortality Salience and Financial Decision-Making

    PubMed Central

    Zaleskiewicz, Tomasz; Gasiorowska, Agata; Kesebir, Pelin

    2013-01-01

    Four studies tested the idea that saving money can buffer death anxiety and constitute a more effective buffer than spending money. Saving can relieve future-related anxiety and provide people with a sense of control over their fate, thereby rendering death thoughts less threatening. Study 1 found that participants primed with both saving and spending reported lower death fear than controls. Saving primes, however, were associated with significantly lower death fear than spending primes. Study 2 demonstrated that mortality primes increase the attractiveness of more frugal behaviors in save-or-spend dilemmas. Studies 3 and 4 found, in two different cultures (Polish and American), that the activation of death thoughts prompts people to allocate money to saving as opposed to spending. Overall, these studies provided evidence that saving protects from existential anxiety, and probably more so than spending. PMID:24244497

  4. Saving can save from death anxiety: mortality salience and financial decision-making.

    PubMed

    Zaleskiewicz, Tomasz; Gasiorowska, Agata; Kesebir, Pelin

    2013-01-01

    Four studies tested the idea that saving money can buffer death anxiety and constitute a more effective buffer than spending money. Saving can relieve future-related anxiety and provide people with a sense of control over their fate, thereby rendering death thoughts less threatening. Study 1 found that participants primed with both saving and spending reported lower death fear than controls. Saving primes, however, were associated with significantly lower death fear than spending primes. Study 2 demonstrated that mortality primes increase the attractiveness of more frugal behaviors in save-or-spend dilemmas. Studies 3 and 4 found, in two different cultures (Polish and American), that the activation of death thoughts prompts people to allocate money to saving as opposed to spending. Overall, these studies provided evidence that saving protects from existential anxiety, and probably more so than spending.

  5. Differentiation inducing factor 3 mediates its anti-leukemic effect through ROS-dependent DRP1-mediated mitochondrial fission and induction of caspase-independent cell death

    PubMed Central

    Dubois, Alix; Ginet, Clemence; Furstoss, Nathan; Belaid, Amine; Hamouda, Mohamed Amine; El Manaa, Wedjene; Cluzeau, Thomas; Marchetti, Sandrine; Ricci, Jean Ehrland; Jacquel, Arnaud; Luciano, Frederic; Driowya, Mohsine; Benhida, Rachid

    2016-01-01

    Differentiation-inducing factor (DIF) defines a group of chlorinated hexaphenones that orchestrate stalk-cell differentiation in the slime mold Dictyostelium discoideum (DD). DIF-1 and 3 have also been reported to have tumor inhibiting properties; however, the mechanisms that underlie the effects of these compounds remain poorly defined. Herein, we show that DIF-3 rapidly triggers Ca2+ release and a loss of mitochondrial membrane potential (MMP) in the absence of cytochrome c and Smac release and without caspase activation. Consistently with these findings, we also detected no evidence of apoptosis in cells treated with DIF-3 but instead found that this compound induced autophagy. In addition, DIF-3 promoted mitochondrial fission in K562 and HeLa cells, as assessed by electron and confocal microscopy analysis. Importantly, DIF-3 mediated the phosphorylation and redistribution of dynamin-related protein 1 (DRP1) from the cytoplasmic to the microsomal fraction of K562 cells. Pharmacological inhibition or siRNA silencing of DRP1 not only inhibited mitochondrial fission but also protected K562 cells from DIF-3-mediated cell death. Furthermore, DIF-3 potently inhibited the growth of imatinib-sensitive and imatinib-resistant K562 cells. It also inhibited tumor formation in athymic mice engrafted with an imatinib-resistant CML cell line. Finally, DIF-3 exhibited a clear selectivity toward CD34+ leukemic cells from CML patients, compared with CD34− cells. In conclusion, we show that the potent anti-leukemic effect of DIF-3 is mediated through the induction of mitochondrial fission and caspase-independent cell death. Our findings may have important therapeutic implications, especially in the treatment of tumors that exhibit defects in apoptosis regulation. PMID:27027430

  6. Methyl succinate antagonises biguanide-induced AMPK-activation and death of pancreatic β-cells through restoration of mitochondrial electron transfer

    PubMed Central

    Hinke, S A; Martens, G A; Cai, Y; Finsi, J; Heimberg, H; Pipeleers, D; Van de Casteele, M

    2007-01-01

    Background and purpose: Two mechanisms have been proposed to explain the insulin-sensitising properties of metformin in peripheral tissues: (a) inhibition of electron transport chain complex I, and (b) activation of the AMP activated protein kinase (AMPK). However the relationship between these mechanisms and their contribution to β-cell death and dysfunction in vitro, are currently unclear. Experimental approach: The effects of biguanides (metformin and phenformin) were tested on MIN6 β-cells and primary FACS-purified rat β-cells. Cell metabolism was assessed biochemically and by FACS analysis, and correlated with AMPK phosphorylation state and cell viability, with or without fuel substrates. Key results: In MIN6 cells, metformin reduced mitochondrial complex I activity by up to 44% and a 25% net reduction in mitochondrial reducing potential. In rat β-cells, metformin caused NAD(P)H accumulation above maximal glucose-inducible levels, mimicking the effect of rotenone. Drug exposure caused phosphorylation of AMPK on Thr172 in MIN6 cell extracts, indicative of kinase activation. Methyl succinate, a complex II substrate, appeared to bypass metformin blockade of complex I. This resulted in reduced phosphorylation of AMPK, establishing a link between biguanide-induced mitochondrial inhibition and AMPK activation. Corresponding assessment of cell death indicated that methyl succinate decreased biguanide toxicity to β-cells in vitro. Conclusions and implications: AMPK activation can partly be attributed to metformin's inhibitory action on mitochondrial complex I. Anaplerotic fuel metabolism via complex II rescued β-cells from metformin-associated toxicity. We propose that utilisation of anaplerotic nutrients may reconcile in vitro and in vivo effects of metformin on the pancreatic β-cell. PMID:17339833

  7. Differentiation inducing factor 3 mediates its anti-leukemic effect through ROS-dependent DRP1-mediated mitochondrial fission and induction of caspase-independent cell death.

    PubMed

    Dubois, Alix; Ginet, Clemence; Furstoss, Nathan; Belaid, Amine; Hamouda, Mohamed Amine; El Manaa, Wedjene; Cluzeau, Thomas; Marchetti, Sandrine; Ricci, Jean Ehrland; Jacquel, Arnaud; Luciano, Frederic; Driowya, Mohsine; Benhida, Rachid; Auberger, Patrick; Robert, Guillaume

    2016-05-01

    Differentiation-inducing factor (DIF) defines a group of chlorinated hexaphenones that orchestrate stalk-cell differentiation in the slime mold Dictyostelium discoideum (DD). DIF-1 and 3 have also been reported to have tumor inhibiting properties; however, the mechanisms that underlie the effects of these compounds remain poorly defined. Herein, we show that DIF-3 rapidly triggers Ca2+ release and a loss of mitochondrial membrane potential (MMP) in the absence of cytochrome c and Smac release and without caspase activation. Consistently with these findings, we also detected no evidence of apoptosis in cells treated with DIF-3 but instead found that this compound induced autophagy. In addition, DIF-3 promoted mitochondrial fission in K562 and HeLa cells, as assessed by electron and confocal microscopy analysis. Importantly, DIF-3 mediated the phosphorylation and redistribution of dynamin-related protein 1 (DRP1) from the cytoplasmic to the microsomal fraction of K562 cells. Pharmacological inhibition or siRNA silencing of DRP1 not only inhibited mitochondrial fission but also protected K562 cells from DIF-3-mediated cell death. Furthermore, DIF-3 potently inhibited the growth of imatinib-sensitive and imatinib-resistant K562 cells. It also inhibited tumor formation in athymic mice engrafted with an imatinib-resistant CML cell line. Finally, DIF-3 exhibited a clear selectivity toward CD34+ leukemic cells from CML patients, compared with CD34- cells. In conclusion, we show that the potent anti-leukemic effect of DIF-3 is mediated through the induction of mitochondrial fission and caspase-independent cell death. Our findings may have important therapeutic implications, especially in the treatment of tumors that exhibit defects in apoptosis regulation.

  8. Differentiation inducing factor 3 mediates its anti-leukemic effect through ROS-dependent DRP1-mediated mitochondrial fission and induction of caspase-independent cell death.

    PubMed

    Dubois, Alix; Ginet, Clemence; Furstoss, Nathan; Belaid, Amine; Hamouda, Mohamed Amine; El Manaa, Wedjene; Cluzeau, Thomas; Marchetti, Sandrine; Ricci, Jean Ehrland; Jacquel, Arnaud; Luciano, Frederic; Driowya, Mohsine; Benhida, Rachid; Auberger, Patrick; Robert, Guillaume

    2016-05-01

    Differentiation-inducing factor (DIF) defines a group of chlorinated hexaphenones that orchestrate stalk-cell differentiation in the slime mold Dictyostelium discoideum (DD). DIF-1 and 3 have also been reported to have tumor inhibiting properties; however, the mechanisms that underlie the effects of these compounds remain poorly defined. Herein, we show that DIF-3 rapidly triggers Ca2+ release and a loss of mitochondrial membrane potential (MMP) in the absence of cytochrome c and Smac release and without caspase activation. Consistently with these findings, we also detected no evidence of apoptosis in cells treated with DIF-3 but instead found that this compound induced autophagy. In addition, DIF-3 promoted mitochondrial fission in K562 and HeLa cells, as assessed by electron and confocal microscopy analysis. Importantly, DIF-3 mediated the phosphorylation and redistribution of dynamin-related protein 1 (DRP1) from the cytoplasmic to the microsomal fraction of K562 cells. Pharmacological inhibition or siRNA silencing of DRP1 not only inhibited mitochondrial fission but also protected K562 cells from DIF-3-mediated cell death. Furthermore, DIF-3 potently inhibited the growth of imatinib-sensitive and imatinib-resistant K562 cells. It also inhibited tumor formation in athymic mice engrafted with an imatinib-resistant CML cell line. Finally, DIF-3 exhibited a clear selectivity toward CD34+ leukemic cells from CML patients, compared with CD34- cells. In conclusion, we show that the potent anti-leukemic effect of DIF-3 is mediated through the induction of mitochondrial fission and caspase-independent cell death. Our findings may have important therapeutic implications, especially in the treatment of tumors that exhibit defects in apoptosis regulation. PMID:27027430

  9. Mitochondrial Cardiomyopathies

    PubMed Central

    El-Hattab, Ayman W.; Scaglia, Fernando

    2016-01-01

    Mitochondria are found in all nucleated human cells and perform various essential functions, including the generation of cellular energy. Mitochondria are under dual genome control. Only a small fraction of their proteins are encoded by mitochondrial DNA (mtDNA), whereas more than 99% of them are encoded by nuclear DNA (nDNA). Mutations in mtDNA or mitochondria-related nDNA genes result in mitochondrial dysfunction leading to insufficient energy production required to meet the needs for various organs, particularly those with high energy requirements, including the central nervous system, skeletal and cardiac muscles, kidneys, liver, and endocrine system. Because cardiac muscles are one of the high energy demanding tissues, cardiac involvement occurs in mitochondrial diseases with cardiomyopathies being one of the most frequent cardiac manifestations found in these disorders. Cardiomyopathy is estimated to occur in 20–40% of children with mitochondrial diseases. Mitochondrial cardiomyopathies can vary in severity from asymptomatic status to severe manifestations including heart failure, arrhythmias, and sudden cardiac death. Hypertrophic cardiomyopathy is the most common type; however, mitochondrial cardiomyopathies might also present as dilated, restrictive, left ventricular non-compaction, and histiocytoid cardiomyopathies. Cardiomyopathies are frequent manifestations of mitochondrial diseases associated with defects in electron transport chain complexes subunits and their assembly factors, mitochondrial transfer RNAs, ribosomal RNAs, ribosomal proteins, translation factors, mtDNA maintenance, and coenzyme Q10 synthesis. Other mitochondrial diseases with cardiomyopathies include Barth syndrome, Sengers syndrome, TMEM70-related mitochondrial complex V deficiency, and Friedreich ataxia. PMID:27504452

  10. Mitochondrial Cardiomyopathies.

    PubMed

    El-Hattab, Ayman W; Scaglia, Fernando

    2016-01-01

    Mitochondria are found in all nucleated human cells and perform various essential functions, including the generation of cellular energy. Mitochondria are under dual genome control. Only a small fraction of their proteins are encoded by mitochondrial DNA (mtDNA), whereas more than 99% of them are encoded by nuclear DNA (nDNA). Mutations in mtDNA or mitochondria-related nDNA genes result in mitochondrial dysfunction leading to insufficient energy production required to meet the needs for various organs, particularly those with high energy requirements, including the central nervous system, skeletal and cardiac muscles, kidneys, liver, and endocrine system. Because cardiac muscles are one of the high energy demanding tissues, cardiac involvement occurs in mitochondrial diseases with cardiomyopathies being one of the most frequent cardiac manifestations found in these disorders. Cardiomyopathy is estimated to occur in 20-40% of children with mitochondrial diseases. Mitochondrial cardiomyopathies can vary in severity from asymptomatic status to severe manifestations including heart failure, arrhythmias, and sudden cardiac death. Hypertrophic cardiomyopathy is the most common type; however, mitochondrial cardiomyopathies might also present as dilated, restrictive, left ventricular non-compaction, and histiocytoid cardiomyopathies. Cardiomyopathies are frequent manifestations of mitochondrial diseases associated with defects in electron transport chain complexes subunits and their assembly factors, mitochondrial transfer RNAs, ribosomal RNAs, ribosomal proteins, translation factors, mtDNA maintenance, and coenzyme Q10 synthesis. Other mitochondrial diseases with cardiomyopathies include Barth syndrome, Sengers syndrome, TMEM70-related mitochondrial complex V deficiency, and Friedreich ataxia. PMID:27504452

  11. The binary switch that controls the life and death decisions of ER stressed beta cells

    PubMed Central

    Oslowski, Christine M.; Urano, Fumihiko

    2010-01-01

    Diabetes mellitus is a group of common metabolic disorders defined by hyperglycemia. One of the most important factors contributing to hyperglycemia is dysfunction and death of β cells. Increasing experimental, clinical, and genetic evidence indicates that endoplasmic reticulum (ER) stress plays an important role in β cell dysfunction and death during the progression of type 1 and type 2 diabetes as well as genetic forms of diabetes such as Wolfram syndrome. The mechanisms of ER stress-mediated β cell dysfunction and death are complex and not homogenous. Here we review the recent key findings on the role of ER stress and the unfolded protein response (UPR) in β cells and the mechanisms of ER stress mediated β cell dysfunction and death. Complete understanding of these mechanisms will lead to novel therapeutic modalities for diabetes. PMID:21168319

  12. Decisive role of apurinic/apyrimidinic endonuclease/Ref-1 in initiation of cell death.

    PubMed

    Cho, Kyoung Joo; Kim, Hyun Jeong; Park, Soo Chul; Kim, Hyun Woo; Kim, Gyung Whan

    2010-11-01

    The apurinic/apyrimidinic endonuclease/redox effector factor-1 (APE/Ref-1) is involved in the base excision repair of apurinic/apyrimidinic sites induced by oxidative DNA damage. APE/Ref-1 was decreased by kainic acid (KA) injury in a time-dependent manner at the level of proteins, not transcripts. We investigated whether alteration of APE/Ref-1 amounts would influence hippocampal cell fate, survival or death, after KA injury. Overexpression of APE/Ref-1 using adenovirus and restoration of APE small peptides significantly reduced KA-induced hippocampal cell death. Both silencing of APE/Ref-1 by siRNA and inhibition of endonuclease by an antibody significantly increased caspase-3 activity and apoptotic cell death triggered from the early time after exposure to KA. These findings suggest that cell death is initiated by reducing APE/Ref-1 protein and inhibiting its repair function in spite of enough protein amounts. In conclusion, APE/Ref-1 may be a regulator of cell death initiation, and APE small peptides could provide molecular mechanism-based therapies for neuroprotection in progressive excitotoxic neuronal damage.

  13. Interleukin-1beta induces death in chondrocyte-like ATDC5 cells through mitochondrial dysfunction and energy depletion in a reactive nitrogen and oxygen species-dependent manner.

    PubMed

    Yasuhara, Rika; Miyamoto, Yoichi; Akaike, Takaaki; Akuta, Teruo; Nakamura, Masanori; Takami, Masamichi; Morimura, Naoko; Yasu, Kayoko; Kamijo, Ryutaro

    2005-07-15

    IL-1 (interleukin-1) acts as a key mediator of the degeneration of articular cartilage in RA (rheumatoid arthritis) and OA (osteoarthritis),where chondrocyte death is observed. It is still controversial, however, whether IL-1 induces chondrocyte death. In the present study, the viability of mouse chondrocyte-like ATDC5 cells was reduced by the treatment with IL-1beta for 48 h or longer. IL-1beta augmented the expression of the catalytic gp91 subunit of NADPH oxidase, gp91phox, as well as inducible NO synthase in ATDC5 cells. Generation of nitrated guanosine and tyrosine suggested the formation of reactive nitrogen species including ONOO- (peroxynitrite), a reaction product of NO and O2-, in ATDC5 cells and rat primary chondrocytes treated with IL-1beta. Death of ATDC5 cells after IL-1beta treatment was prevented by an NADPH-oxidase inhibitor, AEBSF[4-(2-aminoethyl)benzene-sulphonyl fluoride], an NO synthase inhibitor, L-NAME (NG-nitro-L-arginine methyl ester), and a ONOO- scavenger, uric acid. The viability of ATDC5 cells was reduced by the ONOO(-)-generator 3-(4-morpholinyl)sydnonimine hydrochloride, but not by either the NO-donor 1-hydroxy-2-oxo-3-(N-methyl-2-aminopropyl)-3-methyl-1-triazene or S-nitrosoglutathione. Disruption of mitochondrial membrane potential and ATP deprivation were observed in IL-1beta-treated ATDC5 cells, both of which were restored by L-NAME, AEBSF or uric acid. On the other hand, no morphological or biochemical signs indicating apoptosis were observed in these cells. These results suggest that the death of chondrocyte-like ATDC5 cells was mediated at least in part by mitochondrial dysfunction and energy depletion through ONOO- formation after IL-1beta treatment. PMID:15784009

  14. The influence of mitigation evidence, ethnicity, and SES on death penalty decisions by European American and Latino venire persons.

    PubMed

    Espinoza, Russ K E; Willis-Esqueda, Cynthia

    2015-04-01

    The purpose of the research was to determine whether European American and Latino mock jurors would demonstrate bias in death penalty decision making when mitigation evidence and defendant ethnicity and socioeconomic status (SES) were varied. A total of 561 actual venire persons acted as mock jurors and read a trial transcript that varied a defendant's case information (mitigating circumstances: strong/weak, defendant ethnicity: European American/Latino, and defendant SES: low/high). European American jurors recommended the death penalty significantly more often for the low SES Latino defendant when strength of mitigation evidence was weak. In addition, they also assigned this defendant higher culpability ratings and lower ratings on positive personality trait measures compared with all other conditions. Strong mitigation evidence contributed to lower guilt ratings by European American jurors for the high SES European American defendant. Latino jurors did not differ in their death penalty sentencing across defendant mitigation, ethnicity, or SES conditions. Discussion of in-group favoritism and out-group derogation, as well as suggestions for procedures to diminish juror bias in death penalty cases, is provided.

  15. The influence of mitigation evidence, ethnicity, and SES on death penalty decisions by European American and Latino venire persons.

    PubMed

    Espinoza, Russ K E; Willis-Esqueda, Cynthia

    2015-04-01

    The purpose of the research was to determine whether European American and Latino mock jurors would demonstrate bias in death penalty decision making when mitigation evidence and defendant ethnicity and socioeconomic status (SES) were varied. A total of 561 actual venire persons acted as mock jurors and read a trial transcript that varied a defendant's case information (mitigating circumstances: strong/weak, defendant ethnicity: European American/Latino, and defendant SES: low/high). European American jurors recommended the death penalty significantly more often for the low SES Latino defendant when strength of mitigation evidence was weak. In addition, they also assigned this defendant higher culpability ratings and lower ratings on positive personality trait measures compared with all other conditions. Strong mitigation evidence contributed to lower guilt ratings by European American jurors for the high SES European American defendant. Latino jurors did not differ in their death penalty sentencing across defendant mitigation, ethnicity, or SES conditions. Discussion of in-group favoritism and out-group derogation, as well as suggestions for procedures to diminish juror bias in death penalty cases, is provided. PMID:25150818

  16. Controlling the unfolded protein response-mediated life and death decisions in cancer.

    PubMed

    Maurel, Marion; McGrath, Eoghan P; Mnich, Katarzyna; Healy, Sandra; Chevet, Eric; Samali, Afshin

    2015-08-01

    Cancer cells are exposed to intrinsic (oncogene) or extrinsic (microenvironmental) challenges, leading to activation of stress response pathways. The unfolded protein response (UPR) is the cellular response to endoplasmic reticulum (ER) stress and plays a pivotal role in tumor development. Depending on ER stress intensity and duration, the UPR is either pro-survival to preserve ER homeostasis or pro-death if the stress cannot be resolved. On one hand, the adaptive arm of the UPR is essential for cancer cells to survive the harsh conditions they are facing, and on the other hand, cancer cells have evolved mechanisms to bypass ER stress-induced cell death, thereby conferring them with a selective advantage for malignant transformation. Therefore, the mechanisms involved in the balance between survival and death outcomes of the UPR may be exploited as therapeutic tools to treat cancer.

  17. Decisions that hasten death: double effect and the experiences of physicians in Australia

    PubMed Central

    2014-01-01

    Background In Australian end-of-life care, practicing euthanasia or physician-assisted suicide is illegal. Despite this, death hastening practices are common across medical settings. Practices can be clandestine or overt but in many instances physicians are forced to seek protection behind ambiguous medico-legal imperatives such as the Principle of Double Effect. Moreover, the way they conceptualise and experience such practices is inconsistent. To complement the available statistical data, the purpose of this study was to understand the reasoning behind how and why physicians in Australia will hasten death. Method A qualitative investigation was focused on palliative and critical/acute settings. A thematic analysis was conducted on semi-structured in-depth interviews with 13 specialist physicians. Attention was given to eliciting meanings and experiences in Australian end-of-life care. Results Highlighting the importance of a multidimensional approach, physicians negotiated multiple influences when death was regarded as hastened. The way they understood and experienced end-of-life care practices were affected by politico-religious and cultural influences, medico-legal imperatives, and personal values and beliefs. Interpersonal and intrapsychic aspects further emphasised the emotional and psychological investment physicians have with patients and others. In most cases death occurred as a result of treating suffering, and sometimes to fulfil the wishes of patients and others who requested death. Experience was especially subject to the efficacy with which physicians negotiated complex but context-specific situations, and was reflective of how they considered a good death. Although many were compelled to draw on the Principle of Double Effect, every physician reported its inadequacy as a medico-legal guideline. Conclusions The Principle of Double Effect, as a simplistic and generalised guideline, was identified as a convenient mechanism to protect physicians who

  18. The apoptotic effect of hesperetin on human cervical cancer cells is mediated through cell cycle arrest, death receptor, and mitochondrial pathways.

    PubMed

    Alshatwi, Ali A; Ramesh, E; Periasamy, V S; Subash-Babu, P

    2013-12-01

    Hesperetin, a flavonoid from citrus fruits, has several bioactivities such as anti-inflammatory, antihypertensive, antiatherogenic effects. However, studies elucidating the role and the mechanism(s) of action of hesperetin in cervical cancer are sparse. In this study, we investigated the mechanism of the antiproliferative and apoptotic actions exerted by hesperetin on human cervical cancer SiHa cells. The viability of SiHa cells was evaluated using the MTT assay, apoptosis by acridine orange/ethidium bromide, propidium iodide, TUNEL assay, and Annexin V-Cy3, cell cycle distribution and mitochondrial transmembrane potential using flow cytometry, and apoptotic marker genes using quantitative real-time PCR. The treatment of SiHa cells with hesperetin (IC50, 650 μm) showed a marked concentration- and time-dependent inhibition of proliferation and induced the G2/M phase in a dose-dependent manner after 24 h. There was an attenuation of mitochondrial membrane potential with increased expression of caspase-3, caspase-8, caspase-9, p53, Bax, and Fas death receptor and its adaptor protein Fas-associated death domain-containing protein (FADD), indicating the participation of both death receptor- and mitochondria-related mechanisms. Furthermore, hesperetin-induced apoptosis was confirmed by TUNEL and Annexin V-Cy3. This study shows that hesperetin exhibits a potential anticancer activity against human cervical cancer cell lines in vitro through the reduction in cell viability and the induction of apoptosis. Altogether, these data sustain our contention that hesperetin has anticancer properties and merits further investigation as a potential therapeutic agent.

  19. MiADMSA reverses impaired mitochondrial energy metabolism and neuronal apoptotic cell death after arsenic exposure in rats

    SciTech Connect

    Dwivedi, Nidhi; Mehta, Ashish; Yadav, Abhishek; Binukumar, B.K.; Gill, Kiran Dip; Flora, Swaran J.S.

    2011-11-15

    Arsenicosis, due to contaminated drinking water, is a serious health hazard in terms of morbidity and mortality. Arsenic induced free radicals generated are known to cause cellular apoptosis through mitochondrial driven pathway. In the present study, we investigated the effect of arsenic interactions with various complexes of the electron transport chain and attempted to evaluate if there was any complex preference of arsenic that could trigger apoptosis. We also evaluated if chelation with monoisoamyl dimercaptosuccinic acid (MiADMSA) could reverse these detrimental effects. Our results indicate that arsenic exposure induced free radical generation in rat neuronal cells, which diminished mitochondrial potential and enzyme activities of all the complexes of the electron transport chain. Moreover, these complexes showed differential responses towards arsenic. These early events along with diminished ATP levels could be co-related with the later events of cytosolic migration of cytochrome c, altered bax/bcl{sub 2} ratio, and increased caspase 3 activity. Although MiADMSA could reverse most of these arsenic-induced altered variables to various extents, DNA damage remained unaffected. Our study for the first time demonstrates the differential effect of arsenic on the complexes leading to deficits in bioenergetics leading to apoptosis in rat brain. However, more in depth studies are warranted for better understanding of arsenic interactions with the mitochondria. -- Research highlights: Black-Right-Pointing-Pointer Arsenic impairs mitochondrial energy metabolism leading to neuronal apoptosis. Black-Right-Pointing-Pointer Arsenic differentially affects mitochondrial complexes, I - III and IV being more sensitive than complex II. Black-Right-Pointing-Pointer Arsenic-induced apoptosis initiates through ROS generation or impaired [Ca{sup 2+}]i homeostasis. Black-Right-Pointing-Pointer MiADMSA reverses arsenic toxicity via intracellular arsenic- chelation, antioxidant

  20. Involvement of the mitochondrial apoptotic pathway and nitric oxide synthase in dopaminergic neuronal death induced by 6-hydroxydopamine and lipopolysaccharide.

    PubMed

    Singh, Sarika; Kumar, Sachin; Dikshit, Madhu

    2010-01-01

    The primary pathology in Parkinson's disease patients is significant loss of dopaminergic neurons in the substantia nigra through multiple mechanisms. We previously have demonstrated the involvement of nitric oxide (NO) in the dopaminergic neurodegeneration induced by 6-hydroxydopamine (6-OHDA) and lipopolysaccharide (LPS) in rats. The present study was undertaken to investigate further the role of NO in the mitochondria-mediated apoptosis of dopaminergic neurons during the early time period after administration of 6-OHDA and LPS. Measurement of dopamine and its metabolites, TH immunolabeling, cytochrome-c release, mitochondrial complex-I and caspase-3 activity assessment was performed in both the 6-OHDA- and LPS-induced experimental models of Parkinson's disease. Significant decreases in dopamine, 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), tyrosine hydroxylase (TH) immunolabeling and mitochondrial complex-I activity were observed, with increase in cytochrome-c release and caspase-3 activation. Dopmaine and its metabolite levels, mitochondrial complex-I activity and caspase-3 activity were significantly reversed with treatment of the NOS inhibitor, L-NAME. The reduction in the extent of cytochrome-c release responded variably to NOS inhibition in both the models. The results obtained suggest that NO contributes to mitochondria-mediated neuronal apoptosis in the dopaminergic neurodegeneration induced by 6-OHDA and LPS in rats. PMID:20594414

  1. Age-based disparities in end-of-life decisions in Belgium: a population-based death certificate survey

    PubMed Central

    2012-01-01

    Background A growing body of scientific research is suggesting that end-of-life care and decision making may differ between age groups and that elderly patients may be the most vulnerable to exclusion of due care at the end of life. This study investigates age-related disparities in the rate of end-of-life decisions with a possible or certain life shortening effect (ELDs) and in the preceding decision making process in Flanders, Belgium in 2007, where euthanasia was legalised in 2002. Comparing with data from an identical survey in 1998 we also study the plausibility of the ‘slippery slope’ hypothesis which predicts a rise in the rate of administration of life ending drugs without patient request, especially among elderly patients, in countries where euthanasia is legal. Method We performed a post-mortem survey among physicians certifying a large representative sample (n = 6927) of death certificates in 2007, identical to a 1998 survey. Response rate was 58.4%. Results While the rates of non-treatment decisions (NTD) and administration of life ending drugs without explicit request (LAWER) did not differ between age groups, the use of intensified alleviation of pain and symptoms (APS) and euthanasia/assisted suicide (EAS), as well as the proportion of euthanasia requests granted, was bivariately and negatively associated with patient age. Multivariate analysis showed no significant effects of age on ELD rates. Older patients were less often included in decision making for APS and more often deemed lacking in capacity than were younger patients. Comparison with 1998 showed a decrease in the rate of LAWER in all age groups except in the 80+ age group where the rate was stagnant. Conclusion Age is not a determining factor in the rate of end-of-life decisions, but is in decision making as patient inclusion rates decrease with old age. Our results suggest there is a need to focus advance care planning initiatives on elderly patients. The slippery slope hypothesis

  2. Yeast growth in raffinose results in resistance to acetic-acid induced programmed cell death mostly due to the activation of the mitochondrial retrograde pathway.

    PubMed

    Guaragnella, Nicoletta; Zdralević, Maša; Lattanzio, Paolo; Marzulli, Domenico; Pracheil, Tammy; Liu, Zhengchang; Passarella, Salvatore; Marra, Ersilia; Giannattasio, Sergio

    2013-12-01

    In order to investigate whether and how a modification of mitochondrial metabolism can affect yeast sensitivity to programmed cell death (PCD) induced by acetic acid (AA-PCD), yeast cells were grown on raffinose, as a sole carbon source, which, differently from glucose, favours mitochondrial respiration. We found that, differently from glucose-grown cells, raffinose-grown cells were mostly resistant to AA-PCD and that this was due to the activation of mitochondrial retrograde (RTG) response, which increased with time, as revealed by the up-regulation of the peroxisomal isoform of citrate synthase and isocitrate dehydrogenase isoform 1, RTG pathway target genes. Accordingly, the deletion of RTG2 and RTG3, a positive regulator and a transcription factor of the RTG pathway, resulted in AA-PCD, as shown by TUNEL assay. Neither deletion in raffinose-grown cells of HAP4, encoding the positive regulatory subunit of the Hap2,3,4,5 complex nor constitutive activation of the RTG pathway in glucose-grown cells due to deletion of MKS1, a negative regulator of RTG pathway, had effect on yeast AA-PCD. The RTG pathway was found to be activated in yeast cells containing mitochondria, in which membrane potential was measured, capable to consume oxygen in a manner stimulated by the uncoupler CCCP and inhibited by the respiratory chain inhibitor antimycin A. AA-PCD resistance in raffinose-grown cells occurs with a decrease in both ROS production and cytochrome c release as compared to glucose-grown cells en route to AA-PCD. PMID:23906793

  3. Anthracenedione derivative 1403P-3 induces apoptosis in KB and KBv200 cells via reactive oxygen species-independent mitochondrial pathway and death receptor pathway.

    PubMed

    Zhang, Jian-ye; Wu, Hai-ying; Xia, Xue-kui; Liang, Yong-ju; Yan, Yan-yan; She, Zhi-gang; Lin, Yong-cheng; Fu, Li-wu

    2007-09-01

    Anthracenedione derivatives are potent cytotoxic agents to tumor cells. In this study, we investigated the anticancer activities of anthracenedione derivative 1403P-3 separated from the secondary metabolites of the mangrove endophytic fungus No. 1403. Our results demonstrated that 1403P-3 showed potent cytotoxicity not only to human epidermoid carcinoma drug-sensitive parental KB cells but also to multidrug resistant (MDR) KBv200 cells and the IC50 values were 19.66 and 19.27 muM, respectively. Further research indicated that 1403P-3 induced apoptosis in KB cells and KBv200 cells confirmed by Hoechst 33258 staining, detection of DNA fragmentation and cleavage of poly (ADP-ribose) polymerase (PARP). Furthermore, apoptosis triggered by 1403P-3 was characterized by the loss of mitochondrial membrane potential (DeltaPsi(m)), release of cytochrome c, cleavage of Bid, and activation of caspases-2, -3, -7, -8 and -9. Z-IETD-FMK, caspase-8 inhibitor could inhibit the activation of caspase-2 and cleavage of Bid induced by 1403P-3. However, activation of caspase-9 and cleavage of PARP caused by 1403P-3 were not inhibited by Z-IETD-FMK. Additionally, 1403P-3 did not influence the expression level of Bcl-2 and Bax. It is noteworthy that 1403P-3 decreased the generation of reactive oxygen species (ROS) in KB cells and KBv200 cells. DNA binding assay exhibited that apoptosis induced by 1403P-3 was not involved in intercalating to DNA. In summary, 1403P-3 induced apoptosis of KB cells and KBv200 cells through mitochondrial pathway and death receptor pathway. Furthermore, the mitochondrial pathway was independent of reactive oxygen species and activation of caspase-8. PMID:17786034

  4. Yeast growth in raffinose results in resistance to acetic-acid induced programmed cell death mostly due to the activation of the mitochondrial retrograde pathway.

    PubMed

    Guaragnella, Nicoletta; Zdralević, Maša; Lattanzio, Paolo; Marzulli, Domenico; Pracheil, Tammy; Liu, Zhengchang; Passarella, Salvatore; Marra, Ersilia; Giannattasio, Sergio

    2013-12-01

    In order to investigate whether and how a modification of mitochondrial metabolism can affect yeast sensitivity to programmed cell death (PCD) induced by acetic acid (AA-PCD), yeast cells were grown on raffinose, as a sole carbon source, which, differently from glucose, favours mitochondrial respiration. We found that, differently from glucose-grown cells, raffinose-grown cells were mostly resistant to AA-PCD and that this was due to the activation of mitochondrial retrograde (RTG) response, which increased with time, as revealed by the up-regulation of the peroxisomal isoform of citrate synthase and isocitrate dehydrogenase isoform 1, RTG pathway target genes. Accordingly, the deletion of RTG2 and RTG3, a positive regulator and a transcription factor of the RTG pathway, resulted in AA-PCD, as shown by TUNEL assay. Neither deletion in raffinose-grown cells of HAP4, encoding the positive regulatory subunit of the Hap2,3,4,5 complex nor constitutive activation of the RTG pathway in glucose-grown cells due to deletion of MKS1, a negative regulator of RTG pathway, had effect on yeast AA-PCD. The RTG pathway was found to be activated in yeast cells containing mitochondria, in which membrane potential was measured, capable to consume oxygen in a manner stimulated by the uncoupler CCCP and inhibited by the respiratory chain inhibitor antimycin A. AA-PCD resistance in raffinose-grown cells occurs with a decrease in both ROS production and cytochrome c release as compared to glucose-grown cells en route to AA-PCD.

  5. Novel Nitrobenzazolo[3,2-a]quinolinium Salts Induce Cell Death through a Mechanism Involving DNA Damage, Cell Cycle Changes, and Mitochondrial Permeabilization

    PubMed Central

    Vélez, Christian; Cox, Osvaldo; Rosado-Berrios, Carlos A.; Molina, Dennise; Arroyo, Luz; Carro, Sujey; Filikov, Anton; Kumar, Vineet; Malhotra, Sanjay V.; Cordero, Marisol; Zayas, Beatriz

    2014-01-01

    This study reports the capacity of three nitro substituted benzazolo[3,2-a]quinolinium salts NBQs: NBQ 95 (NSC-763304), NBQ 38 (NSC 763305), and NBQ 97 (NSC-763306) as potential antitumor agents. NBQ’s are unnatural alkaloids possessing a positive charge that could facilitate interaction with cell organelles. The anticancer activities of these compounds were evaluated through the National Cancer Institute (NCI) 60 cell line screening which represents diverse histologies. The screening was performed at 10 µM on all cell lines. Results from the NCI screening indicated cytotoxicity activity on six cell lines. In order to explore a possible mechanism of action, a detailed biological activity study of NBQ 95 and NBQ 38 was performed on A431 human epidermoid carcinoma cells to determine an apoptotic pathway involving, cell cycle changes, DNA fragmentation, mutations, mitochondrial membrane permeabilization and caspases activation. DNA fragmentation, cell cycle effects, mutagenesis, mitochondrial permeabilization and activation of caspases were determined by fluorimetry and differential imaging. Our data showed that A431 growth was inhibited with an average IC50 of 30 µM. In terms of the mechanism, these compounds interacted with DNA causing fragmentation and cell cycle arrest at sub G0/G1 stage. Mutagenesis was higher for NBQ 38 and moderate for NBQ 95 Mitochon-drial permeabilization was observed with NBQ 38 and slightly for NBQ 95. Both compounds caused activation of Caspases 3 and 7 suggesting an apoptotic cell death pathway through an intrinsic mechanism. This study reports evidence of the toxicity of these novel compounds with overlapping structural and mechanistic similarities to ellipticine, a known anti-tumor compound. PMID:25243104

  6. Cold ischemia with selective anterograde in situ pulmonary perfusion preserves gas exchange and mitochondrial homeostasis and curbs inflammation in an experimental model of donation after cardiac death.

    PubMed

    Pottecher, Julien; Santelmo, Nicola; Noll, Eric; Charles, Anne-Laure; Benahmed, Malika; Canuet, Matthieu; Frossard, Nelly; Namer, Izzie J; Geny, Bernard; Massard, Gilbert; Diemunsch, Pierre

    2013-10-01

    The aim of this study was to assess the functional preservation of the lung graft with anterograde lung perfusion in a model of donation after cardiac death. Thirty minutes after cardiac arrest, in situ anterograde selective pulmonary cold perfusion was started in six swine. The alveolo-capillary membrane was challenged at 3, 6, and 8 h with measurements of the mean pulmonary arterial pressure (mPAP), the pulmonary vascular resistance (PVR), the PaO2 /FiO2 ratio, the transpulmonary oxygen output (tpVO2 ), and the transpulmonary CO2 clearance (tpCO2 ). Mitochondrial homeostasis was investigated by measuring maximal oxidative capacity (Vmax ) and the coupling of phosphorylation to oxidation (ACR, acceptor control ratio) in lung biopsies. Inflammation and induction of primary immune response were assessed by measurement of tumor necrosis factor alpha (TNFα), interleukine-6 (IL-6) and receptor for advanced glycation endproducts (RAGE) in bronchoalveolar lavage fluid. Data were compared using repeated measures Anova. Pulmonary hemodynamics (mPAP: P = 0.69; PVR: P = 0.46), oxygenation (PaO2 /FiO2 : P = 0.56; tpVO2 : P = 0.46), CO2 diffusion (tpCO2 : P = 0.24), mitochondrial homeostasis (Vmax : P = 0.42; ACR: P = 0.8), and RAGE concentrations (P = 0.24) did not significantly change up to 8 h after cardiac arrest. TNFα and IL-6 were undetectable. Unaffected pulmonary hemodynamics, sustained oxygen and carbon dioxide diffusion, preserved mitochondrial homeostasis, and lack of inflammation suggest a long-lasting functional preservation of the graft with selective anterograde in situ pulmonary perfusion.

  7. Preconditioning with low concentration NO attenuates subsequent NO-induced apoptosis in vascular smooth muscle cells via HO-1-dependent mitochondrial death pathway

    SciTech Connect

    Kwak, Hyun-Jeong; Park, Kyoung-Mi; Lee, Seahyoung; Lim, Hyun-Joung; Go, Sang-Hee; Eom, Sang-Mi; Park, Hyun-Young . E-mail: hypark65@nih.go.kr

    2006-12-01

    Nitric oxide (NO) signaling pathways are important in both the maintenance of vascular homeostasis and disease progression. Overproduction of NO has been associated with ischemia/reperfusion (I/R) injury. Growing evidences suggest that NO preconditioning has cytoprotective effects against I/R injury. However, the mechanism with which NO mediates these effects remains to be elucidated. The purpose of this study was to examine the mechanism of how NO preconditioning inhibits subsequent NO-induced apoptosis in vascular smooth muscle cells (VSMC), specifically focusing on heme oxygenase-1 (HO-1). According to our data, sodium nitroprusside (SNP) increased HO-1 expression in a concentration dependent manner. Preconditioning with low concentration SNP (0.3 mM) inhibited subsequent high concentration SNP (1.5 mM)-induced apoptosis, and this effect was reversed by the HO-1 inhibitor SnPP. Low concentration SNP-mediated protection involved p38 kinase inactivation and increased Bcl-2 expression. Furthermore, mitochondrial membrane potential was concomitantly increased with decreased expressions of Bax, Apaf-1, and activity of caspase-3, which was reversed by SnPP treatment. Our results show that low concentration SNP preconditioning suppresses subsequent high concentration SNP-induced apoptosis by inhibiting p38 kinase and mitochondrial death pathway via HO-1-dependent mechanisms in VSMC.

  8. Hesperidin from Citrus seed induces human hepatocellular carcinoma HepG2 cell apoptosis via both mitochondrial and death receptor pathways.

    PubMed

    Banjerdpongchai, Ratana; Wudtiwai, Benjawan; Khaw-On, Patompong; Rachakhom, Wasitta; Duangnil, Natthachai; Kongtawelert, Prachya

    2016-01-01

    Citrus seeds are full of phenolic compounds, such as flavonoids. The aims of this study were to identify the types of flavonoids in Citrus seed extracts, the cytotoxic effect, mode of cell death, and signaling pathway in human hepatic cancer HepG2 cells. The flavonoids contain anticancer, free radical scavenging, and antioxidant activities. Neohesperidin, hesperidin, and naringin, active flavanone glycosides, were identified in Citrus seed extract. The cytotoxic effect of three compounds was in a dose-dependent manner, and IC50 levels were determined. The sensitivity of human HepG2 cells was as follows: hesperidin > naringin > neohesperidin > naringenin. Hesperidin induced HepG2 cells to undergo apoptosis in a dose-dependent manner as evidenced by the externalization of phosphatidylserine and determined by annexin V-fluorescein isothiocyanate and propidium iodide staining using flow cytometry. Hesperidin did not induce the generation of reactive oxygen species, which was determined by using 2',7'-dichlorohydrofluorescein diacetate and flow cytometry method. The number of hesperidin-treated HepG2 cells with the loss of mitochondrial transmembrane potential increased concentration dependently, using 3,3'-dihexyloxacarbocyanine iodide employing flow cytometry. Caspase-9, -8, and -3 activities were activated and increased in hesperidin-treated HepG2 cells. Bcl-xL protein was downregulated whereas Bax, Bak, and tBid protein levels were upregulated after treatment with hesperidin in a dose-dependent manner. In conclusion, the bioflavanone from Citrus seeds, hesperidin, induced human HepG2 cell apoptosis via mitochondrial pathway and death receptor pathway. Citrus seed flavonoids are beneficial and can be developed as anticancer drug or food supplement, which still needs further in vivo investigation in animals and human beings. PMID:26194866

  9. Critical role of free cytosolic calcium, but not uncoupling, in mitochondrial permeability transition and cell death induced by diclofenac oxidative metabolites in immortalized human hepatocytes

    SciTech Connect

    Lim, M.S.; Lim, Priscilla L.K.; Gupta, Rashi; Boelsterli, Urs A. . E-mail: phcbua@nus.edu.sg

    2006-12-15

    Diclofenac is a widely used nonsteroidal anti-inflammatory drug that has been associated with rare but serious hepatotoxicity. Experimental evidence indicates that diclofenac targets mitochondria and induces the permeability transition (mPT) which leads to apoptotic cell death in hepatocytes. While the downstream effector mechanisms have been well characterized, the more proximal pathways leading to the mPT are not known. The purpose of this study was to explore the role of free cytosolic calcium (Ca{sup 2+} {sub c}) in diclofenac-induced cell injury in immortalized human hepatocytes. We show that exposure to diclofenac caused time- and concentration-dependent cell injury, which was prevented by the specific mPT inhibitor cyclosporin A (CsA, 5 {mu}M). At 8 h, diclofenac caused increases in [Ca{sup 2+}]{sub c} (Fluo-4 fluorescence), which was unaffected by CsA. Combined exposure to diclofenac/BAPTA (Ca{sup 2+} chelator) inhibited cell injury, indicating that Ca{sup 2+} plays a critical role in precipitating mPT. Diclofenac decreased the mitochondrial membrane potential, {delta}{psi}{sub m} (JC-1 fluorescence), even in the presence of CsA or BAPTA, indicating that mitochondrial depolarization was not a consequence of the mPT or elevated [Ca{sup 2+}]{sub c}. The CYP2C9 inhibitor sulphaphenazole (10 {mu}M) protected from diclofenac-induced cell injury and prevented increases in [Ca{sup 2+}]{sub c}, while it had no effect on the dissipation of the {delta}{psi}{sub m}. Finally, diclofenac exposure greatly increased the mitochondria-selective superoxide levels secondary to the increases in [Ca{sup 2+}]{sub c}. In conclusion, these data demonstrate that diclofenac has direct depolarizing effects on mitochondria which does not lead to cell injury, while CYP2C9-mediated bioactivation causes increases in [Ca{sup 2+}]{sub c}, triggering the mPT and precipitating cell death.

  10. Ophiopogonin D attenuates doxorubicin-induced autophagic cell death by relieving mitochondrial damage in vitro and in vivo.

    PubMed

    Zhang, Ying-Yu; Meng, Chen; Zhang, Xin-Mu; Yuan, Cai-Hua; Wen, Ming-Da; Chen, Zhong; Dong, Da-Chuan; Gao, Yan-Hong; Liu, Chang; Zhang, Zhao

    2015-01-01

    It has been reported that ophiopogonin D (OP-D), a steroidal glycoside and an active component extracted from Ophiopogon japonicas, promotes antioxidative protection of the cardiovascular system. However, it is unknown whether OP-D exerts protective effects against doxorubicin (DOX)-induced autophagic cardiomyocyte injury. Here, we demonstrate that DOX induced excessive autophagy through the generation of reactive oxygen species (ROS) in H9c2 cells and in mouse hearts, which was indicated by a significant increase in the number of autophagic vacuoles, LC3-II/LC3-I ratio, and upregulation of the expression of GFP-LC3. Pretreatment with OP-D partially attenuated the above phenomena, similar to the effects of treatment with 3-methyladenine. In addition, OP-D treatment significantly relieved the disruption of the mitochondrial membrane potential by antioxidative effects through downregulating the expression of both phosphorylated c-Jun N-terminal kinase and extracellular signal-regulated kinase. The ability of OP-D to reduce the generation of ROS due to mitochondrial damage and, consequently, to inhibit autophagic activity partially accounts for its protective effects in the hearts against DOX-induced toxicity. PMID:25378375

  11. [6]-Gingerol induces reactive oxygen species regulated mitochondrial cell death pathway in human epidermoid carcinoma A431 cells.

    PubMed

    Nigam, Nidhi; Bhui, Kulpreet; Prasad, Sahdeo; George, Jasmine; Shukla, Yogeshwer

    2009-09-14

    Since skin cancer incidence and prevalence is constantly rising up the charts despite all efforts, search for newer, better agents for protection and treatment is required. Ginger (Zingiber officinale Roscoe), a monocotyledonous herb, is widely used as a herbal medicine, given the presence of homologous phenolic ketones, of which [6]-gingerol is the major one. The quantity of [6]-gingerol in the fresh ginger rhizome was found to be 104-965 microg/g in common varieties of ginger available in Indian market. Herein, [6]-gingerol was assessed for its anti-apoptotic effects in human epidermoid carcinoma A431 cells. [6]-Gingerol treatment exhibited considerable cytotoxicity as indicated by growth inhibition of A431 cells mediated via generation of reactive oxygen species (ROS). Increase in ROS led to decrease in mitochondrial membrane potential (MMP) and subsequent induction of apoptosis. Results revealed that perturbations in mitochondrial membrane are associated with deregulation of Bax/Bcl-2 ratio at gene transcriptional level as well as protein level, where treatment with [6]-gingerol leads to up-regulation of Cytochrome-c and Apaf-1 subsequently culminating in triggering of Caspase cascade. These firmly suggest that [6]-gingerol can be effectively used for the treatment of skin cancer. PMID:19481070

  12. Rapamycin, an mTOR inhibitor, induced apoptosis via independent mitochondrial and death receptor pathway in retinoblastoma Y79 cell

    PubMed Central

    Wang, Yan-Dong; Su, Yong-Jing; Li, Jian-Ying; Yao, Xiang-Chao; Liang, Guang-Jiang

    2015-01-01

    Rapamycin is helpful in the treatment of certain cancers by inhibiting mTOR (mammalian target of rapamycin) pathway. Here, rapamycin mediated apoptosis were investigated in human retinoblastoma Y79 cells. The MTT assay showed that the IC50 value of rapamycin against Y79 cells was 0.136 ± 0.032 μmol/L. Flow cytometry analysis indicated that the percentage of apoptotic cells was increased from 2.16 ± 0.41% to 12.24 ± 3.10%, 20.16 ± 4.22%, and 31.32 ± 5.78% after 0.1, 0.2, and 0.4 μmol/L rapamycin or without rapamycin treatment for 48 hours. Flow cytometry analysis showed that rapamycin induced mitochondrial membrane potential (∆Ψm) collapse in Y79 cells in a concentration-dependent manner. Western blot assay showed that rapamycin led to release of cytochrome c from mitochondrial membranes to cytosol. Further Western blot assays showed that rapamycin induced activation of caspase-9 and caspase-8 and the cleavage of caspase-3. Rapamycin induced cleavages of caspase-3 and apoptosis was inhibited by both Z-LETD-FMK and Z-IETD-FMK treatment. Together, all these results illustrated that rapamycin induced apoptosis in human retinoblastoma Y79 cells involvement of both intrinsic and extrinsic pathways. PMID:26379864

  13. Hemoglobin Control of Cell Survival/Death Decision Regulates in Vitro Plant Embryogenesis1[W][OPEN

    PubMed Central

    Huang, Shuanglong; Hill, Robert D.; Wally, Owen S.D.; Dionisio, Giuseppe; Ayele, Belay T.; Jami, Sravan Kumar; Stasolla, Claudio

    2014-01-01

    Programmed cell death (PCD) in multicellular organisms is a vital process in growth, development, and stress responses that contributes to the formation of tissues and organs. Although numerous studies have defined the molecular participants in apoptotic and PCD cascades, successful identification of early master regulators that target specific cells to live or die is limited. Using Zea mays somatic embryogenesis as a model system, we report that the expressions of two plant hemoglobin (Hb) genes (ZmHb1 and ZmHb2) regulate the cell survival/death decision that influences somatic embryogenesis through their cell-specific localization patterns. Suppression of either of the two ZmHbs is sufficient to induce PCD through a pathway initiated by elevated NO and Zn2+ levels and mediated by production of reactive oxygen species. The effect of the death program on the fate of the developing embryos is dependent on the localization patterns of the two ZmHbs. During somatic embryogenesis, ZmHb2 transcripts are restricted to a few cells anchoring the embryos to the subtending embryogenic tissue, whereas ZmHb1 transcripts extend to several embryonic domains. Suppression of ZmHb2 induces PCD in the anchoring cells, allowing the embryos to develop further, whereas suppression of ZmHb1 results in massive PCD, leading to abortion. We conclude that regulation of the expression of these ZmHbs has the capability to determine the developmental fate of the embryogenic tissue during somatic embryogenesis through their effect on PCD. This unique regulation might have implications for development and differentiation in other species. PMID:24784758

  14. Inactivation of Akt by arsenic trioxide induces cell death via mitochondrial-mediated apoptotic signaling in SGC-7901 human gastric cancer cells.

    PubMed

    Gao, Yan-Hui; Zhang, Hao-Peng; Yang, Shu-Meng; Yang, Yue; Ma, Yu-Yan; Zhang, Xin-Yu; Yang, Yan-Mei

    2014-04-01

    Arsenic trioxide (As2O3) has been recognized as a potential chemotherapeutic agent, yet the details concerning its mechanism of action in solid cancers remain undetermined. The present study assessed the role of Akt in the cell death induced by As2O3. The MTT assay showed that As2O3 suppressed the proliferation of SGC-7901 cells in a dose- and time-dependent manner. Characteristic apoptotic changes were observed in the As2O3‑treated cells by Hoechst 33342 staining, and FACS analysis showed that As2O3 caused dose-dependent apoptotic cell death. As2O3 activated caspase-3 and -9, and PARP cleavage in a dose-dependent manner. Compromised mitochondrial membrane potential and an increased protein level of Bax indicated involvement of mitochondia. As2O3 decreased the levels of p-Akt (Ser473), p-Akt (Thr308) and p-GSK-3β (Ser9), suggesting that As2O3 inactivated Akt kinase. In addition, LY294002 (a PI3 kinase inhibitor) augmented the apoptosis induced by As2O3. These results demonstrated that inhibition of PI3K/Akt signaling was involved in As2O3-induced apoptosis of gastric cancer SGC-7901 cells. PMID:24482137

  15. Radical Decisions in Cancer: Redox Control of Cell Growth and Death

    PubMed Central

    Sainz, Rosa M.; Lombo, Felipe; Mayo, Juan C.

    2012-01-01

    Free radicals play a key role in many physiological decisions in cells. Since free radicals are toxic to cellular components, it is known that they cause DNA damage, contribute to DNA instability and mutation and thus favor carcinogenesis. However, nowadays it is assumed that free radicals play a further complex role in cancer. Low levels of free radicals and steady state levels of antioxidant enzymes are responsible for the fine tuning of redox status inside cells. A change in redox state is a way to modify the physiological status of the cell, in fact, a more reduced status is found in resting cells while a more oxidative status is associated with proliferative cells. The mechanisms by which redox status can change the proliferative activity of cancer cells are related to transcriptional and posttranscriptional modifications of proteins that play a critical role in cell cycle control. Since cancer cells show higher levels of free radicals compared with their normal counterparts, it is believed that the anti-oxidative stress mechanism is also increased in cancer cells. In fact, the levels of some of the most important antioxidant enzymes are elevated in advanced status of some types of tumors. Anti-cancer treatment is compromised by survival mechanisms in cancer cells and collateral damage in normal non-pathological tissues. Though some resistance mechanisms have been described, they do not yet explain why treatment of cancer fails in several tumors. Given that some antitumoral treatments are based on the generation of free radicals, we will discuss in this review the possible role of antioxidant enzymes in the survival mechanism in cancer cells and then, its participation in the failure of cancer treatments. PMID:24213319

  16. Melatonin prevents cytosolic calcium overload, mitochondrial damage and cell death due to toxically high doses of dexamethasone-induced oxidative stress in human neuroblastoma SH-SY5Y cells.

    PubMed

    Suwanjang, Wilasinee; Abramov, Andrey Y; Charngkaew, Komgrid; Govitrapong, Piyarat; Chetsawang, Banthit

    2016-07-01

    Stressor exposure activates the hypothalamic-pituitary-adrenal (HPA) axis and causes elevations in the levels of glucocorticoids (GC) from the adrenal glands. Increasing evidence has demonstrated that prolonged exposure to high GC levels can lead to oxidative stress, calcium deregulation, mitochondrial dysfunction and apoptosis in a number of cell types. However, melatonin, via its antioxidant activity, exhibits a neuroprotective effect against oxidative stress-induced cell death. Therefore, in the present study, we explored the protective effect of melatonin in GC-induced toxicity in human neuroblastoma SH-SY5Y cells. Cellular treatment with the toxically high doses of the synthetic GC receptor agonist, dexamethasone (DEX) elicited marked decreases in the levels of glutathione and increases in ROS production, lipid peroxidation and cell death. DEX toxicity also induced increases in the levels of cytosolic calcium and mitochondrial fusion proteins (Mfn1 and Opa1) but decreases in the levels of mitochondrial fission proteins (Fis1 and Drp1). Mitochondrial damage was observed in large proportions of the DEX-treated cells. Pretreatment of the cells with melatonin substantially prevented the DEX-induced toxicity. These results suggest that melatonin might exert protective effects against oxidative stress, cytosolic calcium overload and mitochondrial damage in DEX-induced neurotoxicity. PMID:27155536

  17. Cinnamaldehyde-induced apoptosis in human hepatoma PLC/PRF/5 cells involves the mitochondrial death pathway and is sensitive to inhibition by cyclosporin A and z-VAD-fmk.

    PubMed

    Lin, Liang-Tzung; Tai, Chen-Jei; Chang, Shun-Pang; Chen, Jin-Liang; Wu, Shu-Jing; Lin, Chun-Ching

    2013-12-01

    Cinnamaldehyde (CIN) has been shown to exert chemopreventive activity against several types of human cancer cells. We previously reported that CIN induced apoptosis of human hepatoma PLC/PRF/5 cells and this effect was associated with activation of the pro-apoptotic Bcl-2 family of proteins and the MAPK cascade. To further clarify the underlying mechanism of CIN-induced apoptosis, we examined in this study its relationship with the mitochondrial death pathway using the mitochondrial permeability transition (MPT) inhibitor, cyclosporin A (CsA), and the general caspase inhibitor, z-VAD-fmk. Results indicated that CIN-induced apoptosis involved enhanced ROS generation, disruption of mitochondrial potential, and the mitochondrial release of cytochrome c and Smac/DIABLO into the cytosol, which in turn promoted caspase-3 to its active form and the subsequent cleavage of PARP. Treatment with CIN also downregulated protein levels of the anti-apoptotic factors XIAP and Bcl-2 with concomitant accumulation of the pro-apoptotic Bax in a timedependent manner. These mitochondria-related apoptotic effects induced by CIN were however blocked by CsA and z-VAD-fmk pretreatments, which prevented cells from undergoing programmed cell death triggered by CIN. Furthermore, the increase of Bax and decrease of Bcl-2 and XIAP protein expression due to CIN treatment were also reversely modulated by the two inhibitors. Taken together, these results suggested that CIN is an apoptotic inducer that acts on the mitochondrial death pathway in PLC/PRF/5 cells and its effect could be blocked by CsA and z-VAD-fmk.

  18. Curcumin induces apoptotic cell death of activated human CD4+ T cells via increasing endoplasmic reticulum stress and mitochondrial dysfunction.

    PubMed

    Zheng, Min; Zhang, Qinggao; Joe, Yeonsoo; Lee, Bong Hee; Ryu, Do Gon; Kwon, Kang Beom; Ryter, Stefan W; Chung, Hun Taeg

    2013-03-01

    Curcumin, a natural polyphenolic antioxidant compound, exerts well-known anti-inflammatory and immunomodulatory effects, the latter which can influence the activation of immune cells including T cells. Furthermore, curcumin can inhibit the expression of pro-inflammatory cytokines and chemokines, through suppression of the NF-κB signaling pathway. The beneficial effects of curcumin in diseases such as arthritis, allergy, asthma, atherosclerosis, diabetes and cancer may be due to its immunomodulatory properties. We studied the potential of curcumin to modulate CD4+ T cells-mediated autoimmune disease, by examining the effects of this compound on human CD4+ lymphocyte activation. Stimulation of human T cells with PHA or CD3/CD28 induced IL-2 mRNA expression and activated the endoplasmic reticulum (ER) stress response. The treatment of T cells with curcumin induced the unfolded protein response (UPR) signaling pathway, initiated by the phosphorylation of PERK and IRE1. Furthermore, curcumin increased the expression of the ER stress associated transcriptional factors XBP-1, cleaved p50ATF6α and C/EBP homologous protein (CHOP) in human CD4+ and Jurkat T cells. In PHA-activated T cells, curcumin further enhanced PHA-induced CHOP expression and reduced the expression of the anti-apoptotic protein Bcl-2. Finally, curcumin treatment induced apoptotic cell death in activated T cells via eliciting an excessive ER stress response, which was reversed by the ER-stress inhibitor 4-phenylbutyric acid or transfection with CHOP-specific siRNA. These results suggest that curcumin can impact both ER stress and mitochondria functional pathways, and thereby could be used as a promising therapy in the context of Th1-mediated autoimmune diseases. PMID:23415873

  19. Enzymatic dysfunction of mitochondrial complex I of the Candida albicans goa1 mutant is associated with increased reactive oxidants and cell death.

    PubMed

    Li, Dongmei; Chen, Hui; Florentino, Abigail; Alex, Deepu; Sikorski, Patricia; Fonzi, William A; Calderone, Richard

    2011-05-01

    We have previously shown that deletion of GOA1 (growth and oxidant adaptation) of Candida albicans results in a loss of mitochondrial membrane potential, ATP synthesis, increased sensitivity to oxidants and killing by human neutrophils, and avirulence in a systemic model of candidiasis. We established that translocation of Goa1p to mitochondria occurred during peroxide stress. In this report, we show that the goa1Δ (GOA31), compared to the wild type (WT) and a gene-reconstituted (GOA32) strain, exhibits sensitivity to inhibitors of the classical respiratory chain (CRC), including especially rotenone (complex I [CI]) and salicylhydroxamic acid (SHAM), an inhibitor of the alternative oxidase pathway (AOX), while potassium cyanide (KCN; CIV) causes a partial inhibition of respiration. In the presence of SHAM, however, GOA31 has an enhanced respiration, which we attribute to the parallel respiratory (PAR) pathway and alternative NADH dehydrogenases. Interestingly, deletion of GOA1 also results in a decrease in transcription of the alternative oxidase gene AOX1 in untreated cells as well as negligible AOX1 and AOX2 transcription in peroxide-treated cells. To explain the rotenone sensitivity, we measured enzyme activities of complexes I to IV (CI to CIV) and observed a major loss of CI activity in GOA31 but not in control strains. Enzymatic data of CI were supported by blue native polyacrylamide gel electrophoresis (BN-PAGE) experiments which demonstrated less CI protein and reduced enzyme activity. The consequence of a defective CI in GOA31 is an increase in reactive oxidant species (ROS), loss of chronological aging, and programmed cell death ([PCD] apoptosis) in vitro compared to control strains. The increase in PCD was indicated by an increase in caspase activity and DNA fragmentation in GOA31. Thus, GOA1 is required for a functional CI and partially for the AOX pathway; loss of GOA1 compromises cell survival. Further, the loss of chronological aging is new to

  20. Mitochondrial regulation of apoptosis.

    PubMed

    Mayer, Bernd; Oberbauer, Rainer

    2003-06-01

    Mitochondria play a central part in cellular survival and apoptotic death. These processes are highly regulated by pro- and antiapoptotic Bcl-2 superfamily members. A key feature within apoptosis cascades is disruption of mitochondrial transmembrane potential and apoptogenic protein release, caused by opening of the permeability transition pore (PT). New data, however, indicate that mitochondrial apoptosis may occur without PT involvement.

  1. What matters to the parents? A qualitative study of parents' experiences with life-and-death decisions concerning their premature infants.

    PubMed

    Brinchmann, Berit Støre; Førde, Reidun; Nortvedt, Per

    2002-07-01

    The aim of this article is to generate knowledge about parents' participation in life-and-death decisions concerning their very premature and/or critically ill infants in hospital neonatal units. The question is: what are parents' attitudes towards their involvement in such decision making? A descriptive study design using in-depth interviews was chosen. During the period 1997-2000, 20 qualitative interviews with 35 parents of 26 children were carried out. Ten of the infants died; 16 were alive at the time of the interview. The comparative method (grounded theory) was used to analyse the data. The analysis was carried out continuously and in parallel with data collection. Six categories were revealed by the analysis: indecision and uncertainty (ambivalence); information and communication; participate, but do not decide; seeming to be included; the parents' child; and individual consideration. The findings appear to indicate that parents agree that they should not have the final word in decisions concerning their infants' future life or death. Such a responsibility would put too heavy a burden on parents who lack the medical knowledge and the professional experience needed to make such a decision, and would be likely to lead to them experiencing strong feelings of guilt. The findings show that parents should be well informed and listened to during the whole decision-making process. Their primary concern was how nurses and physicians communicate with parents who are experiencing a crisis, and how this serious information is presented.

  2. Mitigating Circumstances in Death Penalty Decisions: Using Evidence-Based Research to Inform Social Work Practice in Capital Trials

    ERIC Educational Resources Information Center

    Schroeder, Julie; Guin, Cecile C.; Pogue, Rene; Bordelon, Danna

    2006-01-01

    Providing an effective defense for individuals charged with capital crimes requires a diligent, thorough investigation by a mitigation specialist. However, research suggests that mitigation often plays a small role in the decision for life. Jurors often make sentencing decisions prematurely, basing those decisions on their personal reactions to…

  3. Mitochondrial dysfunction, impaired oxidative-reduction activity, degeneration, and death in human neuronal and fetal cells induced by low-level exposure to thimerosal and other metal compounds

    PubMed Central

    Geier, D.A.; King, P.G.; Geier, M.R.

    2009-01-01

    Thimerosal (ethylmercurithiosalicylic acid), an ethylmercury (EtHg)-releasing compound (49.55% mercury (Hg)), was used in a range of medical products for more than 70 years. Of particular recent concern, routine administering of Thimerosal-containing biologics/childhood vaccines have become significant sources of Hg exposure for some fetuses/infants. This study was undertaken to investigate cellular damage among in vitro human neuronal (SH-SY-5Y neuroblastoma and 1321N1 astrocytoma) and fetal (nontransformed) model systems using cell vitality assays and microscope-based digital image capture techniques to assess potential damage induced by Thimerosal and other metal compounds (aluminum (Al) sulfate, lead (Pb)(II) acetate, methylmercury (MeHg) hydroxide, and mercury (Hg)(II) chloride) where the cation was reported to exert adverse effects on developing cells. Thimerosal-associated cellular damage was also evaluated for similarity to pathophysiological findings observed in patients diagnosed with autistic disorders (ADs). Thimerosal-induced cellular damage as evidenced by concentration- and time-dependent mitochondrial damage, reduced oxidative–reduction activity, cellular degeneration, and cell death in the in vitro human neuronal and fetal model systems studied. Thimerosal at low nanomolar (nM) concentrations induced significant cellular toxicity in human neuronal and fetal cells. Thimerosal-induced cytoxicity is similar to that observed in AD pathophysiologic studies. Thimerosal was found to be significantly more toxic than the other metal compounds examined. Future studies need to be conducted to evaluate additional mechanisms underlying Thimerosal-induced cellular damage and assess potential co-exposures to other compounds that may increase or decrease Thimerosal-mediated toxicity. PMID:24532866

  4. Inhibition of N-Methyl-D-aspartate-induced Retinal Neuronal Death by Polyarginine Peptides Is Linked to the Attenuation of Stress-induced Hyperpolarization of the Inner Mitochondrial Membrane Potential.

    PubMed

    Marshall, John; Wong, Kwoon Y; Rupasinghe, Chamila N; Tiwari, Rakesh; Zhao, Xiwu; Berberoglu, Eren D; Sinkler, Christopher; Liu, Jenney; Lee, Icksoo; Parang, Keykavous; Spaller, Mark R; Hüttemann, Maik; Goebel, Dennis J

    2015-09-01

    It is widely accepted that overactivation of NMDA receptors, resulting in calcium overload and consequent mitochondrial dysfunction in retinal ganglion neurons, plays a significant role in promoting neurodegenerative disorders such as glaucoma. Calcium has been shown to initiate a transient hyperpolarization of the mitochondrial membrane potential triggering a burst of reactive oxygen species leading to apoptosis. Strategies that enhance cell survival signaling pathways aimed at preventing this adverse hyperpolarization of the mitochondrial membrane potential may provide a novel therapeutic intervention in retinal disease. In the retina, brain-derived neurotrophic factor has been shown to be neuroprotective, and our group previously reported a PSD-95/PDZ-binding cyclic peptide (CN2097) that augments brain-derived neurotrophic factor-induced pro-survival signaling. Here, we examined the neuroprotective properties of CN2097 using an established retinal in vivo NMDA toxicity model. CN2097 completely attenuated NMDA-induced caspase 3-dependent and -independent cell death and PARP-1 activation pathways, blocked necrosis, and fully prevented the loss of long term ganglion cell viability. Although neuroprotection was partially dependent upon CN2097 binding to the PDZ domain of PSD-95, our results show that the polyarginine-rich transport moiety C-R(7), linked to the PDZ-PSD-95-binding cyclic peptide, was sufficient to mediate short and long term protection via a mitochondrial targeting mechanism. C-R(7) localized to mitochondria and was found to reduce mitochondrial respiration, mitochondrial membrane hyperpolarization, and the generation of reactive oxygen species, promoting survival of retinal neurons.

  5. Inhibition of N-Methyl-d-aspartate-induced Retinal Neuronal Death by Polyarginine Peptides Is Linked to the Attenuation of Stress-induced Hyperpolarization of the Inner Mitochondrial Membrane Potential*

    PubMed Central

    Marshall, John; Wong, Kwoon Y.; Rupasinghe, Chamila N.; Tiwari, Rakesh; Zhao, Xiwu; Berberoglu, Eren D.; Sinkler, Christopher; Liu, Jenney; Lee, Icksoo; Parang, Keykavous; Spaller, Mark R.; Hüttemann, Maik; Goebel, Dennis J.

    2015-01-01

    It is widely accepted that overactivation of NMDA receptors, resulting in calcium overload and consequent mitochondrial dysfunction in retinal ganglion neurons, plays a significant role in promoting neurodegenerative disorders such as glaucoma. Calcium has been shown to initiate a transient hyperpolarization of the mitochondrial membrane potential triggering a burst of reactive oxygen species leading to apoptosis. Strategies that enhance cell survival signaling pathways aimed at preventing this adverse hyperpolarization of the mitochondrial membrane potential may provide a novel therapeutic intervention in retinal disease. In the retina, brain-derived neurotrophic factor has been shown to be neuroprotective, and our group previously reported a PSD-95/PDZ-binding cyclic peptide (CN2097) that augments brain-derived neurotrophic factor-induced pro-survival signaling. Here, we examined the neuroprotective properties of CN2097 using an established retinal in vivo NMDA toxicity model. CN2097 completely attenuated NMDA-induced caspase 3-dependent and -independent cell death and PARP-1 activation pathways, blocked necrosis, and fully prevented the loss of long term ganglion cell viability. Although neuroprotection was partially dependent upon CN2097 binding to the PDZ domain of PSD-95, our results show that the polyarginine-rich transport moiety C-R(7), linked to the PDZ-PSD-95-binding cyclic peptide, was sufficient to mediate short and long term protection via a mitochondrial targeting mechanism. C-R(7) localized to mitochondria and was found to reduce mitochondrial respiration, mitochondrial membrane hyperpolarization, and the generation of reactive oxygen species, promoting survival of retinal neurons. PMID:26100636

  6. End-of-life medical decisions in France: a death certificate follow-up survey 5 years after the 2005 act of parliament on patients’ rights and end of life

    PubMed Central

    2012-01-01

    Background The “Patients’ Rights and End of Life Care” Act came into force in France in 2005. It allows withholding/withdrawal of life-support treatment, and intensified use of medications that may hasten death through a double effect, as long as hastening death is not the purpose of the decision. It also specifies the requirements of the decision-making process. This study assesses the situation by examining the frequency of end-of-life decisions by patients’ and physicians’ characteristics, and describes the decision-making processes. Methods We conducted a nationwide retrospective study of a random sample of adult patients who died in December 2009. Questionnaires were mailed to the physicians who certified/attended these deaths. Cases were weighted to adjust for response rate bias. Bivariate analyses and logistic regressions were performed for each decision. Results Of all deaths, 16.9% were sudden deaths with no information about end of life, 12.2% followed a decision to do everything possible to prolong life, and 47.7% followed at least one medical decision that may certainly or probably hasten death: withholding (14.6%) or withdrawal (4.2%) of treatments, intensified use of opioids and/or benzodiazepines (28.1%), use of medications to deliberately hasten death (i.e. not legally authorized) (0.8%), at the patient’s request (0.2%) or not (0.6%). All other variables held constant, cause of death, patient's age, doctor’s age and specialty, and place of death, influenced the frequencies of decisions. When a decision was made, 20% of the persons concerned were considered to be competent. The decision was discussed with the patient if competent in 40% (everything done) to 86% (intensification of alleviation of symptoms) of cases. Legal requirements regarding decision-making for incompetent patients were frequently not complied with. Conclusions This study shows that end-of-life medical decisions are common in France. Most are in compliance with the

  7. Will the S.C.C.'s Decision on Physician-Assisted Death Apply to Persons Suffering from Severe Mental Illness?

    PubMed

    Walker-Renshaw, Barbara; Finley, Margot

    2016-02-01

    In this article, the authors address the question of whether the Supreme Court of Canada's decision in Carter v. Canada leaves open the possibility that persons with severe, treatment-refractory mental illness may lawfully seek a physician-assisted death. If so, how will health care providers distinguish between suicidal ideation and intent that is a symptom of the pathology of a treatable mental illness, on the one hand; and suicidal ideation and intent that is, perhaps, a capable and thoughtful response to a "grievous and irremediable" condition, on the other hand? Mental illness is the most common risk factor for suicide. If physician-assisted death becomes an accepted practice in mental health care, how will that be reconciled with the well-established impetus in mental health care to prevent suicide? The authors consider the competing ethical values of beneficence and promoting patient autonomy, in the context of the recovery movement in mental health care. PMID:27169201

  8. Will the S.C.C.'s Decision on Physician-Assisted Death Apply to Persons Suffering from Severe Mental Illness?

    PubMed

    Walker-Renshaw, Barbara; Finley, Margot

    2016-02-01

    In this article, the authors address the question of whether the Supreme Court of Canada's decision in Carter v. Canada leaves open the possibility that persons with severe, treatment-refractory mental illness may lawfully seek a physician-assisted death. If so, how will health care providers distinguish between suicidal ideation and intent that is a symptom of the pathology of a treatable mental illness, on the one hand; and suicidal ideation and intent that is, perhaps, a capable and thoughtful response to a "grievous and irremediable" condition, on the other hand? Mental illness is the most common risk factor for suicide. If physician-assisted death becomes an accepted practice in mental health care, how will that be reconciled with the well-established impetus in mental health care to prevent suicide? The authors consider the competing ethical values of beneficence and promoting patient autonomy, in the context of the recovery movement in mental health care.

  9. An effect of communication on medical decision making: answerability, and the medically induced death of Paul Mills.

    PubMed

    Kenny, R Wade

    2007-01-01

    In this essay, the occasion of a medically induced death is examined to illustrate how circumstances surrounding a medically induced death are interpreted through a theory of how social agents, on occasion, respond inappropriately. The essay illustrates and assesses an occasion when a health professional, faced with a medical crisis that was laden with professional, ethical, and even legal considerations, responded in a manner that overlooked all those standards when she injected potassium chloride into her patient, Paul Mills. In the essay, the case is chronicled and the character of the social and communicative mechanism that led to the disaster is given and used to interpret the events.

  10. A post-mortem survey on end-of-life decisions using a representative sample of death certificates in Flanders, Belgium: research protocol

    PubMed Central

    Chambaere, Kenneth; Bilsen, Johan; Cohen, Joachim; Pousset, Geert; Onwuteaka-Philipsen, Bregje; Mortier, Freddy; Deliens, Luc

    2008-01-01

    Background Reliable studies of the incidence and characteristics of medical end-of-life decisions with a certain or possible life shortening effect (ELDs) are indispensable for an evidence-based medical and societal debate on this issue. This article presents the protocol drafted for the 2007 ELD Study in Flanders, Belgium, and outlines how the main aims and challenges of the study (i.e. making reliable incidence estimates of end-of-life decisions, even rare ones, and describing their characteristics; allowing comparability with past ELD studies; guaranteeing strict anonymity given the sensitive nature of the research topic; and attaining a sufficient response rate) are addressed in a post-mortem survey using a representative sample of death certificates. Study design Reliable incidence estimates are achievable by using large at random samples of death certificates of deceased persons in Flanders (aged one year or older). This entails the cooperation of the appropriate administrative authorities. To further ensure the reliability of the estimates and descriptions, especially of less prevalent end-of-life decisions (e.g. euthanasia), a stratified sample is drawn. A questionnaire is sent out to the certifying physician of each death sampled. The questionnaire, tested thoroughly and avoiding emotionally charged terms is based largely on questions that have been validated in previous national and European ELD studies. Anonymity of both patient and physician is guaranteed through a rigorous procedure, involving a lawyer as intermediary between responding physicians and researchers. To increase response we follow the Total Design Method (TDM) with a maximum of three follow-up mailings. Also, a non-response survey is conducted to gain insight into the reasons for lack of response. Discussion The protocol of the 2007 ELD Study in Flanders, Belgium, is appropriate for achieving the objectives of the study; as past studies in Belgium, the Netherlands, and other European

  11. Mitochondrial DNA damage and atherosclerosis.

    PubMed

    Yu, Emma P K; Bennett, Martin R

    2014-09-01

    Mitochondria are often regarded as the cellular powerhouses through their ability to generate ATP, the universal fuel for metabolic processes. However, in recent years mitochondria have been recognised as critical regulators of cell death, inflammation, metabolism, and the generation of reactive oxygen species (ROS). Thus, mitochondrial dysfunction directly promotes cell death, inflammation, and oxidative stress and alters metabolism. These are key processes in atherosclerosis and there is now evidence that mitochondrial DNA (mtDNA) damage leads to mitochondrial dysfunction and promotes atherosclerosis directly. In this review we discuss the recent evidence for and mechanisms linking mtDNA defects and atherosclerosis and suggest areas of mitochondrial biology that are potential therapeutic targets.

  12. Mitigating circumstances in death penalty decisions: using evidence-based research to inform social work practice in capital trials.

    PubMed

    Schroeder, Julie; Guin, Cecile C; Pogue, Rene; Bordelon, Danna

    2006-10-01

    Providing an effective defense for individuals charged with capital crimes requires a diligent, thorough investigation by a mitigation specialist. However, research suggests that mitigation often plays a small role in the decision for life. Jurors often make sentencing decisions prematurely, basing those decisions on their personal reactions to the defendant (for example, fear, anger), their confusion about the rules of law, and their lack of understanding regarding their role and responsibilities. This article proposes an evidence-based conceptual model of the complicating problems surrounding mitigation practice and a focused discussion about how traditional social work mitigation strategies might be evolved to a set of best practices that more effectively ensure jurors' careful consideration of mitigation evidence.

  13. GSH depletion, protein S-glutathionylation and mitochondrial transmembrane potential hyperpolarization are early events in initiation of cell death induced by a mixture of isothiazolinones in HL60 cells.

    PubMed

    Di Stefano, Anna; Frosali, Simona; Leonini, Alessandra; Ettorre, Anna; Priora, Raffaella; Di Simplicio, Francesca Cherubini; Di Simplicio, Paolo

    2006-02-01

    We recently described that brief exposure of HL60 cells to a mixture of 5-chloro-2-methyl-4-isothiazolin-3-one (CMI) and 2-methyl-4-isothiazolin-3-one (MI) induces apoptosis at low concentrations (0.001-0.01%) and necrosis at higher concentrations (0.05-0.1%). In this study, we show that glutathione (GSH) depletion, reactive oxygen species generation, hyperpolarization of mitochondrial transmembrane potential (DeltaPsim) and formation of protein-GSH mixed disulphides (S-glutathionylation) are early molecular events that precede the induction of cell death by CMI/MI. When the cells exhibit common signs of apoptosis, they show activation of caspase-9, reduction of DeltaPsim and, more importantly, decreased protein S-glutathionylation. In contrast, necrosis is associated with severe mitochondrial damage and maximal protein S-glutathionylation. CMI/MI-induced cytotoxicity is also accompanied by decreased activity of GSH-related enzymes. Pre-incubation with L-buthionine-(S,R)-sulfoximine (BSO) clearly switches the mode of cell death from apoptosis to necrosis at 0.01% CMI/MI. Collectively, these results demonstrate that CMI/MI alters the redox status of HL60 cells, and the extent and kinetics of GSH depletion and S-glutathionylation appear to determine whether cells undergo apoptosis or necrosis. We hypothesize that S-glutathionylation of certain thiol groups accompanied by GSH depletion plays a critical role in the molecular mechanism of CMI/MI cytotoxicity.

  14. Production of Reactive Oxygen Species, Alteration of Cytosolic Ascorbate Peroxidase, and Impairment of Mitochondrial Metabolism Are Early Events in Heat Shock-Induced Programmed Cell Death in Tobacco Bright-Yellow 2 Cells1

    PubMed Central

    Vacca, Rosa Anna; de Pinto, Maria Concetta; Valenti, Daniela; Passarella, Salvatore; Marra, Ersilia; De Gara, Laura

    2004-01-01

    To gain some insight into the mechanisms by which plant cells die as a result of abiotic stress, we exposed tobacco (Nicotiana tabacum) Bright-Yellow 2 cells to heat shock and investigated cell survival as a function of time after heat shock induction. Heat treatment at 55°C triggered processes leading to programmed cell death (PCD) that was complete after 72 h. In the early phase, cells undergoing PCD showed an immediate burst in hydrogen peroxide (H2O2) and superoxide (O2·-) anion production. Consistently, death was prevented by the antioxidants ascorbate (ASC) and superoxide dismutase (SOD). Actinomycin D and cycloheximide, inhibitors of transcription and translation, respectively, also prevented cell death, but with a lower efficiency. Induction of PCD resulted in gradual oxidation of endogenous ASC; this was accompanied by a decrease in both the amount and the specific activity of the cytosolic ASC peroxidase (cAPX). A reduction in cAPX gene expression was also found in the late PCD phase. Moreover, changes of cAPX kinetic properties were found in PCD cells. Production of ROS in PCD cells was accompanied by early inhibition of glucose (Glc) oxidation, with a strong impairment of mitochondrial function as shown by an increase in cellular NAD(P)H fluorescence, and by failure of mitochondria isolated from cells undergoing PCD to generate membrane potential and to oxidize succinate in a manner controlled by ADP. Thus, we propose that in the early phase of tobacco Bright-Yellow 2 cell PCD, ROS production occurs, perhaps because of damage of the cell antioxidant system, with impairment of the mitochondrial oxidative phosphorylation. PMID:15020761

  15. Ornithine and Homocitrulline Impair Mitochondrial Function, Decrease Antioxidant Defenses and Induce Cell Death in Menadione-Stressed Rat Cortical Astrocytes: Potential Mechanisms of Neurological Dysfunction in HHH Syndrome.

    PubMed

    Zanatta, Ângela; Rodrigues, Marília Danyelle Nunes; Amaral, Alexandre Umpierrez; Souza, Débora Guerini; Quincozes-Santos, André; Wajner, Moacir

    2016-09-01

    Hyperornithinemia-hyperammonemia-homocitrullinuria (HHH) syndrome is caused by deficiency of ornithine translocase leading to predominant tissue accumulation and high urinary excretion of ornithine (Orn), homocitrulline (Hcit) and ammonia. Although affected patients commonly present neurological dysfunction manifested by cognitive deficit, spastic paraplegia, pyramidal and extrapyramidal signs, stroke-like episodes, hypotonia and ataxia, its pathogenesis is still poorly known. Although astrocytes are necessary for neuronal protection. Therefore, in the present study we investigated the effects of Orn and Hcit on cell viability (propidium iodide incorporation), mitochondrial function (thiazolyl blue tetrazolium bromide-MTT-reduction and mitochondrial membrane potential-ΔΨm), antioxidant defenses (GSH) and pro-inflammatory response (NFkB, IL-1β, IL-6 and TNF-α) in unstimulated and menadione-stressed cortical astrocytes that were previously shown to be susceptible to damage by neurotoxins. We first observed that Orn decreased MTT reduction, whereas both amino acids decreased GSH levels, without altering cell viability and the pro-inflammatory factors in unstimulated astrocytes. Furthermore, Orn and Hcit decreased cell viability and ΔΨm in menadione-treated astrocytes. The present data indicate that the major compounds accumulating in HHH syndrome impair mitochondrial function and reduce cell viability and the antioxidant defenses in cultured astrocytes especially when stressed by menadione. It is presumed that these mechanisms may be involved in the neuropathology of this disease. PMID:27161368

  16. Ornithine and Homocitrulline Impair Mitochondrial Function, Decrease Antioxidant Defenses and Induce Cell Death in Menadione-Stressed Rat Cortical Astrocytes: Potential Mechanisms of Neurological Dysfunction in HHH Syndrome.

    PubMed

    Zanatta, Ângela; Rodrigues, Marília Danyelle Nunes; Amaral, Alexandre Umpierrez; Souza, Débora Guerini; Quincozes-Santos, André; Wajner, Moacir

    2016-09-01

    Hyperornithinemia-hyperammonemia-homocitrullinuria (HHH) syndrome is caused by deficiency of ornithine translocase leading to predominant tissue accumulation and high urinary excretion of ornithine (Orn), homocitrulline (Hcit) and ammonia. Although affected patients commonly present neurological dysfunction manifested by cognitive deficit, spastic paraplegia, pyramidal and extrapyramidal signs, stroke-like episodes, hypotonia and ataxia, its pathogenesis is still poorly known. Although astrocytes are necessary for neuronal protection. Therefore, in the present study we investigated the effects of Orn and Hcit on cell viability (propidium iodide incorporation), mitochondrial function (thiazolyl blue tetrazolium bromide-MTT-reduction and mitochondrial membrane potential-ΔΨm), antioxidant defenses (GSH) and pro-inflammatory response (NFkB, IL-1β, IL-6 and TNF-α) in unstimulated and menadione-stressed cortical astrocytes that were previously shown to be susceptible to damage by neurotoxins. We first observed that Orn decreased MTT reduction, whereas both amino acids decreased GSH levels, without altering cell viability and the pro-inflammatory factors in unstimulated astrocytes. Furthermore, Orn and Hcit decreased cell viability and ΔΨm in menadione-treated astrocytes. The present data indicate that the major compounds accumulating in HHH syndrome impair mitochondrial function and reduce cell viability and the antioxidant defenses in cultured astrocytes especially when stressed by menadione. It is presumed that these mechanisms may be involved in the neuropathology of this disease.

  17. Topical Administration of the Mitochondrial PTP Opening Inhibitor CoQ10 Prevents Apoptotic Cell Death Induced by UVC-Irradiation in Rat's Corneas and Rabbit's Retinas

    NASA Astrophysics Data System (ADS)

    Papucci, Laura; Witort, Ewa; Schiavone, Nicola; Donnini, Martino; Lapucci, Andrea; Lulli, Matteo; Lazzarano, Stefano; Simoncini, Madine; Mazzoni, Tiziano; Falciani, Piergiuseppe; Capaccioli, Sergio

    2008-06-01

    We have previously demonstrated in vitro that ubiquitous free radical scavenger coenzyme Q10 prevents keratocyte apoptosis induced by excimer laser irradiation more efficiently than other antioxidants. We showed that its anti apoptotic property is independent of its free radical scavenging ability and is related to direct inhibition of PTP (permeability transition pore) opening and mitochondrial depolarization. Here, we demonstrate in vivo, that CoQ10 can efficiently protect rat's corneas and rabbit's retinas irradiated with UVC. Therefore, we propose application of CoQ10 as countermeasure to prevent micro radiation-induced eye damage during interplanetary space exploration.

  18. Benzyl alcohol protects against acetaminophen hepatotoxicity by inhibiting cytochrome P450 enzymes but causes mitochondrial dysfunction and cell death at higher doses.

    PubMed

    Du, Kuo; McGill, Mitchell R; Xie, Yuchao; Jaeschke, Hartmut

    2015-12-01

    Acetaminophen (APAP) hepatotoxicity is a serious public health problem in western countries. Current treatment options for APAP poisoning are limited and novel therapeutic intervention strategies are needed. A recent publication suggested that benzyl alcohol (BA) protects against APAP hepatotoxicity and could serve as a promising antidote for APAP poisoning. To assess the protective mechanisms of BA, C56Bl/6J mice were treated with 400 mg/kg APAP and/or 270 mg/kg BA. APAP alone caused extensive liver injury at 6 h and 24 h post-APAP. This injury was attenuated by BA co-treatment. Assessment of protein adduct formation demonstrated that BA inhibits APAP metabolic activation. In support of this, in vitro experiments also showed that BA dose-dependently inhibits cytochrome P450 activities. Correlating with the hepatoprotection of BA, APAP-induced oxidant stress and mitochondrial dysfunction were reduced. Similar results were obtained in primary mouse hepatocytes. Interestingly, BA alone caused mitochondrial membrane potential loss and cell toxicity at high doses, and its protective effect could not be reproduced in primary human hepatocytes (PHH). We conclude that BA protects against APAP hepatotoxicity mainly by inhibiting cytochrome P450 enzymes in mice. Considering its toxic effect and the loss of protection in PHH, BA is not a clinically useful treatment option for APAP overdose patient. PMID:26522885

  19. Cordyceps militaris induces tumor cell death via the caspase-dependent mitochondrial pathway in HepG2 and MCF-7 cells

    PubMed Central

    SONG, JINGJING; WANG, YINGWU; TENG, MEIYU; ZHANG, SHIQIANG; YIN, MENGYA; LU, JIAHUI; LIU, YAN; LEE, ROBERT J; WANG, DI; TENG, LESHENG

    2016-01-01

    Cordyceps militaris (CM), an entomopathogenic fungus belonging to the class ascomycetes, possesses various pharmacological activities, including cytotoxic effects, on various types of human tumor cells. The present study investigated the anti-hepatocellular carcinoma (HCC) and anti-breast cancer effects of CM in in vitro and in vivo models. CM aqueous extract reduced cell viability, suppressed cell proliferation, inhibited cell migration ability, caused the over-release of lactate dehydrogenase, induced mitochondrial dysfunction and enhanced apoptotic rates in MCF-7 and HepG2 cells. The expression levels of cleaved poly (ADP ribose) polymerase and caspase-3, biomarkers of apoptosis, were increased following treatment with CM aqueous extract for 24 h. Furthermore, in the MCF-7 and HepG2 cells, enhanced levels of B cell-associated X protein and cleaved caspase-8 were observed in the CM-treated cells. Finally, the antitumor activities of CM in HCC and breast cancer were also confirmed in MCF-7- and HepG2-xengraft nude mice models. Collectively, the data obtained in the present study suggested that the cytotoxic effects of CM aqueous extract on HCC and breast cancer are associated with the caspase-dependent mitochondrial pathway. PMID:27109250

  20. Cordyceps militaris induces tumor cell death via the caspase‑dependent mitochondrial pathway in HepG2 and MCF‑7 cells.

    PubMed

    Song, Jingjing; Wang, Yingwu; Teng, Meiyu; Zhang, Shiqiang; Yin, Mengya; Lu, Jiahui; Liu, Yan; Lee, Robert J; Wang, Di; Teng, Lesheng

    2016-06-01

    Cordyceps militaris (CM), an entomopathogenic fungus belonging to the class ascomycetes, possesses various pharmacological activities, including cytotoxic effects, on various types of human tumor cells. The present study investigated the anti‑hepatocellular carcinoma (HCC) and anti‑breast cancer effects of CM in in vitro and in vivo models. CM aqueous extract reduced cell viability, suppressed cell proliferation, inhibited cell migration ability, caused the over-release of lactate dehydrogenase, induced mitochondrial dysfunction and enhanced apoptotic rates in MCF‑7 and HepG2 cells. The expression levels of cleaved poly (ADP ribose) polymerase and caspase‑3, biomarkers of apoptosis, were increased following treatment with CM aqueous extract for 24 h. Furthermore, in the MCF‑7 and HepG2 cells, enhanced levels of B cell‑associated X protein and cleaved caspase‑8 were observed in the CM‑treated cells. Finally, the antitumor activities of CM in HCC and breast cancer were also confirmed in MCF‑7‑ and HepG2‑xengraft nude mice models. Collectively, the data obtained in the present study suggested that the cytotoxic effects of CM aqueous extract on HCC and breast cancer are associated with the caspase‑dependent mitochondrial pathway. PMID:27109250

  1. Mitochondrial Ion Channels in Cancer Transformation

    PubMed Central

    Madamba, Stephen M.; Damri, Kevin N.; Dejean, Laurent M.; Peixoto, Pablo M.

    2015-01-01

    Cancer transformation involves reprograming of mitochondrial function to avert cell death mechanisms, monopolize energy metabolism, accelerate mitotic proliferation, and promote metastasis. Mitochondrial ion channels have emerged as promising therapeutic targets because of their connection to metabolic and apoptotic functions. This mini review discusses how mitochondrial channels may be associated with cancer transformation and expands on the possible involvement of mitochondrial protein import complexes in pathophysiological process. PMID:26090338

  2. Mitochondrial drug targets in neurodegenerative diseases.

    PubMed

    Lee, Jiyoun

    2016-02-01

    Growing evidence suggests that mitochondrial dysfunction is the main culprit in neurodegenerative diseases. Given the fact that mitochondria participate in diverse cellular processes, including energetics, metabolism, and death, the consequences of mitochondrial dysfunction in neuronal cells are inevitable. In fact, new strategies targeting mitochondrial dysfunction are emerging as potential alternatives to current treatment options for neurodegenerative diseases. In this review, we focus on mitochondrial proteins that are directly associated with mitochondrial dysfunction. We also examine recently identified small molecule modulators of these mitochondrial targets and assess their potential in research and therapeutic applications.

  3. Human rights accountability for maternal death and failure to provide safe, legal abortion: the significance of two ground-breaking CEDAW decisions.

    PubMed

    Kismödi, Eszter; de Mesquita, Judith Bueno; Ibañez, Ximena Andión; Khosla, Rajat; Sepúlveda, Lilian

    2012-06-01

    In 2011, the Committee on the Elimination of Discrimination against Women (CEDAW) issued two landmark decisions. In Alyne da Silva Pimentel v. Brazil, the first maternal death case decided by an international human rights body, it confirms that States have a human rights obligation to guarantee that all women, irrespective of their income or racial background, have access to timely, non-discriminatory, and appropriate maternal health services. In L.C. v. Peru, concerning a 13-year-old rape victim who was denied a therapeutic abortion and had an operation on her spine delayed that left her seriously disabled as a result, it established that the State should guarantee access to abortion when a woman's physical or mental health is in danger, decriminalise abortion when pregnancy results from rape or sexual abuse, review its restrictive interpretation of therapeutic abortion and establish a mechanism to ensure that reproductive rights are understood and observed in all health care facilities. Both cases affirm that accessible and good quality health services are vital to women's human rights and expand States' obligations in relation to these. They also affirm that States must ensure national accountability for sexual and reproductive health rights, and provide remedies and redress in the event of violations. And they reaffirm the importance of international human rights bodies as sources of accountability for sexual and reproductive rights violations, especially where national accountability is absent or ineffective.

  4. Eighth Amendment & Death Penalty.

    ERIC Educational Resources Information Center

    Shortall, Joseph M.; Merrill, Denise W.

    1987-01-01

    Presents a lesson on capital punishment for juveniles based on three hypothetical cases. The goal of the lesson is to have students understand the complexities of decisions regarding the death penalty for juveniles. (JDH)

  5. Cedrol induces autophagy and apoptotic cell death in A549 non-small cell lung carcinoma cells through the P13K/Akt signaling pathway, the loss of mitochondrial transmembrane potential and the generation of ROS.

    PubMed

    Zhang, Shi-Yi; Li, Xue-Bo; Hou, Sheng-Guang; Sun, Yao; Shi, Yi-Ran; Lin, Song-Sen

    2016-07-01

    The objective of the present study was to determine the anticancer effects of cedrol in A549 human non-small cell lung cancer cells by examining the effects of cedrol on apoptosis induction, the phosphatidylinositol 3'-kinase (PI3K)/Akt signaling pathway, autophagy, reactive oxygen species (ROS) generation and mitochondrial transmembrane potential (MTP). The anticancer effects of cedrol were examined using A549 human lung carcinoma cells as an in vitro model. Cell viability was determined using MTT and lactate dehydrogenase (LDH) assays, and an inverted phase contrast microscope was used to examine the morphological changes in these cells. Cedrol‑triggered autophagy was confirmed by transmission electron microscopy (TEM) analysis of the cells, as well as by western blot analysis of microtubule-associated protein light-chain 3 (LC3)B expression. Intracellular ROS generation was measured by flow cytometry using 5-(6)-carboxy-2',7'-dichlorodihydrofluorescein diacetate (CM-DCFH2-DA) staining and MTP was measured using flow cytometry. The results demonstrated that cedrol reduced cell viability and induced cell apoptosis in a dose-dependent manner. Mechanistic evaluations indicated that cedrol induced apoptosis by reducing the MTP and by decreasing the levels of phosphorylated (p-)PI3K and p-Akt. Cedrol induced autophagy, which was confirmed by TEM analysis, by increasing intracellular ROS formation in a concentration-dependent manner, which was almost completely reversed by N-acetyl-L-cysteine (NAC) and tocopherol. Taken together, these findings reveal that cedrol inhibits cell proliferation and induces apoptosis in A549 cells through mitochondrial and PI3K/Akt signaling pathways. Our findings also reveal that cedrol induced pro-death autophagy by increasing intracellular ROS production.

  6. Mitochondrial Diseases

    MedlinePlus

    ... disorder, something goes wrong with this process. Mitochondrial diseases are a group of metabolic disorders. Mitochondria are ... cells and cause damage. The symptoms of mitochondrial disease can vary. It depends on how many mitochondria ...

  7. Human Cu/Zn superoxide dismutase (SOD1) overexpression in mice causes mitochondrial vacuolization, axonal degeneration, and premature motoneuron death and accelerates motoneuron disease in mice expressing a familial amyotrophic lateral sclerosis mutant SOD1.

    PubMed

    Jaarsma, D; Haasdijk, E D; Grashorn, J A; Hawkins, R; van Duijn, W; Verspaget, H W; London, J; Holstege, J C

    2000-12-01

    Cytosolic Cu/Zn superoxide dismutase (SOD1) is a ubiquitous small cytosolic metalloenzyme that catalyzes the conversion of superoxide anion to hydrogen peroxide (H(2)O(2)). Mutations in the SOD1 gene cause a familial form of amyotrophic lateral sclerosis (fALS). The mechanism by which mutant SOD1s causes ALS is not understood. Transgenic mice expressing multiple copies of fALS-mutant SOD1s develop an ALS-like motoneuron disease resembling ALS. Here we report that transgenic mice expressing a high concentration of wild-type human SOD1 (hSOD1(WT)) develop an array of neurodegenerative changes consisting of (1) swelling and vacuolization of mitochondria, predominantly in axons in the spinal cord, brain stem, and subiculum; (2) axonal degeneration in a number of long fiber tracts, predominantly the spinocerebellar tracts; and (3) at 2 years of age, a moderate loss of spinal motoneurons. Parallel to the development of neurodegenerative changes, hSOD1(WT) mice also develop mild motor abnormalities. Interestingly, mitochondrial vacuolization was associated with accumulation of hSOD1 immunoreactivity, suggesting that the development of mitochondrial pathology is associated with disturbed SOD1 turnover. In this study we also crossed hSOD1(WT) mice with a line of fALS-mutant SOD1 mice (hSOD1(G93A)) to generate "double" transgenic mice that express high levels of both wild-type and G93A mutant hSOD1. The "double" transgenic mice show accelerated motoneuron death, earlier onset of paresis, and earlier death as compared with hSOD1(G93A) littermates. Thus in vivo expression of high levels of wild-type hSOD1 is not only harmful to neurons in itself, but also increases or facilitates the deleterious action of a fALS-mutant SOD1. Our data indicate that it is important for motoneurons to control the SOD1 concentration throughout their processes, and that events that lead to improper synthesis, transport, or breakdown of SOD1 causing its accumulation are potentially dangerous.

  8. Metformin Prevents Dopaminergic Neuron Death in MPTP/P-Induced Mouse Model of Parkinson’s Disease via Autophagy and Mitochondrial ROS Clearance

    PubMed Central

    Lu, Ming; Su, Cunjin; Qiao, Chen; Bian, Yaqi; Ding, Jianhua

    2016-01-01

    Background: Our previous study demonstrated that metabolic inflammation exacerbates dopaminergic neuronal degeneration in type 2 diabetes mice. Metformin, a typical oral hypoglycemic agent for diabetes, has been regarded as an activator of AMP-activated protein kinase and a regulator of systemic energy metabolism. Although metformin plays potential protective effects in many disorders, it is unclear whether metformin has a therapeutic role in dopaminergic neuron degeneration in Parkinson’s disease. Methods: In the present study, a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine plus probenecid-induced mouse model of Parkinson’s disease was established to explore the neuroprotective effect of metformin on dopaminergic neurons in substania nigra compacta. We next cultured SH-SY5Y cells to investigate the mechanisms for the neuroprotective effect of metformin. Results: We showed that treatment with metformin (5mg/mL in drinking water) for 5 weeks significantly ameliorated the degeneration of substania nigra compacta dopaminergic neurons, increased striatal dopaminergic levels, and improved motor impairment induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine plus probenecid. We further found that metformin inhibited microglia overactivation-induced neuroinflammation in substania nigra compacta of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine plus probenecid Parkinson’s disease mice, which might contribute to the protective effect of metformin on neurodegeneration. Furthermore, metformin (2mM) activated AMP-activated protein kinase in SH-SY5Y cells, in turn inducing microtubule-associated protein 1 light chain 3-II-mediated autophagy and eliminating mitochondrial reactive oxygen species. Consequently, metformin alleviated MPP+-induced cytotoxicity and attenuated neuronal apoptosis. Conclusions: Our findings demonstrate that metformin may be a pluripotent and promising drug for dopaminergic neuron degeneration, which will give us insight into the potential of

  9. Topological Transitions in Mitochondrial Membranes controlled by Apoptotic Proteins

    NASA Astrophysics Data System (ADS)

    Hwee Lai, Ghee; Sanders, Lori K.; Mishra, Abhijit; Schmidt, Nathan W.; Wong, Gerard C. L.; Ivashyna, Olena; Schlesinger, Paul H.

    2010-03-01

    The Bcl-2 family comprises pro-apoptotic proteins, capable of permeabilizing the mitochondrial membrane, and anti-apoptotic members interacting in an antagonistic fashion to regulate programmed cell death (apoptosis). They offer potential therapeutic targets to re-engage cellular suicide in tumor cells but the extensive network of implicated protein-protein interactions has impeded full understanding of the decision pathway. We show, using synchrotron x-ray diffraction, that pro-apoptotic proteins interact with mitochondrial-like model membranes to generate saddle-splay (negative Gaussian) curvature topologically required for pore formation, while anti-apoptotic proteins can deactivate curvature generation by molecules drastically different from Bcl-2 family members and offer evidence for membrane-curvature mediated interactions general enough to affect very disparate systems.

  10. Bromelain inhibits COX-2 expression by blocking the activation of MAPK regulated NF-kappa B against skin tumor-initiation triggering mitochondrial death pathway.

    PubMed

    Bhui, Kulpreet; Prasad, Sahdeo; George, Jasmine; Shukla, Yogeshwer

    2009-09-18

    Chemoprevention impels the pursuit for either single targeted or cocktail of multi-targeted agents. Bromelain, potential agent in this regard, is a pharmacologically active compound, present in stems and fruits of pineapple (Ananas cosmosus), endowed with anti-inflammatory, anti-invasive and anti-metastatic properties. Herein, we report the anti tumor-initiating effects of bromelain in 2-stage mouse skin tumorigenesis model. Pre-treatment of bromelain resulted in reduction in cumulative number of tumors (CNT) and average number of tumors per mouse. Preventive effect was also comprehended in terms of reduction in tumor volume up to a tune of approximately 65%. Components of the cell signaling pathways, connecting proteins involved in cell death were targeted. Bromelain treatment resulted in upregulation of p53 and Bax and subsequent activation of caspase 3 and caspase 9 with concomitant decrease in Bcl-2. A marked inhibition in cyclooxygenase-2 (Cox-2) expression and inactivation of nuclear factor-kappa B (NF-kappaB) was recorded, as phosphorylation and consequent degradation of I kappa B alpha was blocked by bromelain. Also, bromelain treatment curtailed extracellular signal regulated protein kinase (ERK1/2), p38 mitogen-activated protein kinase (MAPK) and Akt activity. The basis of anti tumor-initiating activity of bromelain was revealed by its time dependent reduction in DNA nick formation and increase in percentage prevention. Thus, modulation of inappropriate cell signaling cascades driven by bromelain is a coherent approach in achieving chemoprevention.

  11. [Brain death and thanatology].

    PubMed

    Zwierlein, E

    1993-09-01

    New technologies in medicine dramatically open a twilight-zone of ignorance between life and death. The argument shows that the present definition of brain death as the death of a human person is a convention with a specific philosophy behind. You will meet the problem with more accuracy when referring to an ethics of intransparence that allows an individual decision with respect to certain qualified conditions. Only from this starting-point the informed ex ante consent for an organ donation seems to become the only conclusive but at the same time justified decision.

  12. Mitochondrial vasculopathy

    PubMed Central

    Finsterer, Josef; Zarrouk-Mahjoub, Sinda

    2016-01-01

    Mitochondrial disorders (MIDs) are usually multisystem disorders (mitochondrial multiorgan disorder syndrome) either on from onset or starting at a point during the disease course. Most frequently affected tissues are those with a high oxygen demand such as the central nervous system, the muscle, endocrine glands, or the myocardium. Recently, it has been shown that rarely also the arteries may be affected (mitochondrial arteriopathy). This review focuses on the type, diagnosis, and treatment of mitochondrial vasculopathy in MID patients. A literature search using appropriate search terms was carried out. Mitochondrial vasculopathy manifests as either microangiopathy or macroangiopathy. Clinical manifestations of mitochondrial microangiopathy include leukoencephalopathy, migraine-like headache, stroke-like episodes, or peripheral retinopathy. Mitochondrial macroangiopathy manifests as atherosclerosis, ectasia of arteries, aneurysm formation, dissection, or spontaneous rupture of arteries. The diagnosis relies on the documentation and confirmation of the mitochondrial metabolic defect or the genetic cause after exclusion of non-MID causes. Treatment is not at variance compared to treatment of vasculopathy due to non-MID causes. Mitochondrial vasculopathy exists and manifests as micro- or macroangiopathy. Diagnosing mitochondrial vasculopathy is crucial since appropriate treatment may prevent from severe complications. PMID:27231520

  13. The Use of Neuroimaging in the Diagnosis of Mitochondrial Disease

    ERIC Educational Resources Information Center

    Friedman, Seth D.; Shaw, Dennis W. W.; Ishak, Gisele; Gropman, Andrea L.; Saneto, Russell P.

    2010-01-01

    Mutations in nuclear and mitochondrial DNA impacting mitochondrial function result in disease manifestations ranging from early death to abnormalities in all major organ systems and to symptoms that can be largely confined to muscle fatigue. The definitive diagnosis of a mitochondrial disorder can be difficult to establish. When the constellation…

  14. Mitochondrial small conductance SK2 channels prevent glutamate-induced oxytosis and mitochondrial dysfunction.

    PubMed

    Dolga, Amalia M; Netter, Michael F; Perocchi, Fabiana; Doti, Nunzianna; Meissner, Lilja; Tobaben, Svenja; Grohm, Julia; Zischka, Hans; Plesnila, Nikolaus; Decher, Niels; Culmsee, Carsten

    2013-04-12

    Small conductance calcium-activated potassium (SK2/K(Ca)2.2) channels are known to be located in the neuronal plasma membrane where they provide feedback control of NMDA receptor activity. Here, we provide evidence that SK2 channels are also located in the inner mitochondrial membrane of neuronal mitochondria. Patch clamp recordings in isolated mitoplasts suggest insertion into the inner mitochondrial membrane with the C and N termini facing the intermembrane space. Activation of SK channels increased mitochondrial K(+) currents, whereas channel inhibition attenuated these currents. In a model of glutamate toxicity, activation of SK2 channels attenuated the loss of the mitochondrial transmembrane potential, blocked mitochondrial fission, prevented the release of proapoptotic mitochondrial proteins, and reduced cell death. Neuroprotection was blocked by specific SK2 inhibitory peptides and siRNA targeting SK2 channels. Activation of mitochondrial SK2 channels may therefore represent promising targets for neuroprotective strategies in conditions of mitochondrial dysfunction.

  15. Mitochondrial calcium uptake.

    PubMed

    Williams, George S B; Boyman, Liron; Chikando, Aristide C; Khairallah, Ramzi J; Lederer, W J

    2013-06-25

    Calcium (Ca(2+)) uptake into the mitochondrial matrix is critically important to cellular function. As a regulator of matrix Ca(2+) levels, this flux influences energy production and can initiate cell death. If large, this flux could potentially alter intracellular Ca(2+) ([Ca(2+)]i) signals. Despite years of study, fundamental disagreements on the extent and speed of mitochondrial Ca(2+) uptake still exist. Here, we review and quantitatively analyze mitochondrial Ca(2+) uptake fluxes from different tissues and interpret the results with respect to the recently proposed mitochondrial Ca(2+) uniporter (MCU) candidate. This quantitative analysis yields four clear results: (i) under physiological conditions, Ca(2+) influx into the mitochondria via the MCU is small relative to other cytosolic Ca(2+) extrusion pathways; (ii) single MCU conductance is ∼6-7 pS (105 mM [Ca(2+)]), and MCU flux appears to be modulated by [Ca(2+)]i, suggesting Ca(2+) regulation of MCU open probability (P(O)); (iii) in the heart, two features are clear: the number of MCU channels per mitochondrion can be calculated, and MCU probability is low under normal conditions; and (iv) in skeletal muscle and liver cells, uptake per mitochondrion varies in magnitude but total uptake per cell still appears to be modest. Based on our analysis of available quantitative data, we conclude that although Ca(2+) critically regulates mitochondrial function, the mitochondria do not act as a significant dynamic buffer of cytosolic Ca(2+) under physiological conditions. Nevertheless, with prolonged (superphysiological) elevations of [Ca(2+)]i, mitochondrial Ca(2+) uptake can increase 10- to 1,000-fold and begin to shape [Ca(2+)]i dynamics.

  16. Death imagery and death anxiety.

    PubMed

    McDonald, R T; Hilgendorf, W A

    1986-01-01

    This study investigated the relationship between positive/negative death imagery and death anxiety. Subjects were 179 undergraduate students at a large, private, midwestern university. Results reveal that on five measures of death anxiety the subjects with low death anxiety scores had significantly more positive death images than did those with high death anxiety scores. The few subjects who imagined death to be young (N = 14) had a significantly more positive image of death than those who perceived it to be an old person. Death was seen as male by 92% of the male respondents and 74% of the female respondents. Significant differences in death imagery and death anxiety were found between subjects enrolled in an introductory psychology course and those enrolled in a thanatology course. No sex differences in death anxiety or positive/negative death imagery were found.

  17. Mitochondrial cytopathies.

    PubMed

    El-Hattab, Ayman W; Scaglia, Fernando

    2016-09-01

    Mitochondria are found in all nucleated human cells and perform a variety of essential functions, including the generation of cellular energy. Most of mitochondrial proteins are encoded by the nuclear DNA (nDNA) whereas a very small fraction is encoded by the mitochondrial DNA (mtDNA). Mutations in mtDNA or mitochondria-related nDNA genes can result in mitochondrial dysfunction which leads to a wide range of cellular perturbations including aberrant calcium homeostasis, excessive reactive oxygen species production, dysregulated apoptosis, and insufficient energy generation to meet the needs of various organs, particularly those with high energy demand. Impaired mitochondrial function in various tissues and organs results in the multi-organ manifestations of mitochondrial diseases including epilepsy, intellectual disability, skeletal and cardiac myopathies, hepatopathies, endocrinopathies, and nephropathies. Defects in nDNA genes can be inherited in an autosomal or X-linked manners, whereas, mtDNA is maternally inherited. Mitochondrial diseases can result from mutations of nDNA genes encoding subunits of the electron transport chain complexes or their assembly factors, proteins associated with the mitochondrial import or networking, mitochondrial translation factors, or proteins involved in mtDNA maintenance. MtDNA defects can be either point mutations or rearrangements. The diagnosis of mitochondrial disorders can be challenging in many cases and is based on clinical recognition, biochemical screening, histopathological studies, functional studies, and molecular genetic testing. Currently, there are no satisfactory therapies available for mitochondrial disorders that significantly alter the course of the disease. Therapeutic options include symptomatic treatment, cofactor supplementation, and exercise. PMID:26996063

  18. The metabolism beyond programmed cell death in yeast

    PubMed Central

    Ring, Julia; Sommer, Cornelia; Carmona-Gutierrez, Didac; Ruckenstuhl, Christoph; Eisenberg, Tobias; Madeo, Frank

    2012-01-01

    A cell's reaction to any change in the endogenous or exogenous conditions often involves a complex response that eventually either leads to cell adaptation and survival or to the initiation and execution of (programmed) cell death. The molecular decision whether to live or die, while depending on a cell's genome, is fundamentally influenced by its actual metabolic status. Thus, the collection of all metabolites present in a biological system at a certain time point (the so-called metabolome) defines its physiological, developmental and pathological state and determines its fate during changing and stressful conditions. The budding yeast Saccharomyces cerevisiae is a unicellular organism that allows to easily modify and monitor conditions affecting the cell's metabolome, for instance through a simple change of the nutrition source. Such changes can be used to mimic and study (patho)physiological scenarios, including caloric restriction and longevity, the Warburg effect in cancer cells or changes in mitochondrial mass affecting cell death. In addition, disruption of single genes or generation of respiratory deficiency (via abrogation of mitochondrial DNA) assists in revealing connections between metabolism and apoptosis. In this minireview, we discuss recent studies using the potential of the yeast model to provide new insights into the processes of stress defense, cell death and longevity. PMID:22480867

  19. Drug-induced mitochondrial dysfunction and cardiotoxicity.

    PubMed

    Varga, Zoltán V; Ferdinandy, Peter; Liaudet, Lucas; Pacher, Pál

    2015-11-01

    Mitochondria has an essential role in myocardial tissue homeostasis; thus deterioration in mitochondrial function eventually leads to cardiomyocyte and endothelial cell death and consequent cardiovascular dysfunction. Several chemical compounds and drugs have been known to directly or indirectly modulate cardiac mitochondrial function, which can account both for the toxicological and pharmacological properties of these substances. In many cases, toxicity problems appear only in the presence of additional cardiovascular disease conditions or develop months/years following the exposure, making the diagnosis difficult. Cardiotoxic agents affecting mitochondria include several widely used anticancer drugs [anthracyclines (Doxorubicin/Adriamycin), cisplatin, trastuzumab (Herceptin), arsenic trioxide (Trisenox), mitoxantrone (Novantrone), imatinib (Gleevec), bevacizumab (Avastin), sunitinib (Sutent), and sorafenib (Nevaxar)], antiviral compound azidothymidine (AZT, Zidovudine) and several oral antidiabetics [e.g., rosiglitazone (Avandia)]. Illicit drugs such as alcohol, cocaine, methamphetamine, ecstasy, and synthetic cannabinoids (spice, K2) may also induce mitochondria-related cardiotoxicity. Mitochondrial toxicity develops due to various mechanisms involving interference with the mitochondrial respiratory chain (e.g., uncoupling) or inhibition of the important mitochondrial enzymes (oxidative phosphorylation, Szent-Györgyi-Krebs cycle, mitochondrial DNA replication, ADP/ATP translocator). The final phase of mitochondrial dysfunction induces loss of mitochondrial membrane potential and an increase in mitochondrial oxidative/nitrative stress, eventually culminating into cell death. This review aims to discuss the mechanisms of mitochondrion-mediated cardiotoxicity of commonly used drugs and some potential cardioprotective strategies to prevent these toxicities. PMID:26386112

  20. Mitochondrial Myopathy

    MedlinePlus

    ... with ragged-red fibers, and mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes. The symptoms of ... riboflavin, coenzyme Q, and carnitine (a specialized amino acid) may provide subjective improvement in fatigue and energy ...

  1. Mitochondrial DNA.

    ERIC Educational Resources Information Center

    Wright, Russell G.; Bottino, Paul J.

    1986-01-01

    Provides background information for teachers on mitochondrial DNA, pointing out that it may have once been a free-living organism. Includes a ready-to-duplicate exercise titled "Using Microchondrial DNA to Measure Evolutionary Distance." (JN)

  2. Mitochondrial Myopathies

    MedlinePlus

    ... line and are therefore called the electron transport chain, and complex V actually churns out ATP, so ... coQ10 , is a component of the electron transport chain, which uses oxygen to manufacture ATP. Some mitochondrial ...

  3. Mitochondrial genetics

    PubMed Central

    Chinnery, Patrick Francis; Hudson, Gavin

    2013-01-01

    Introduction In the last 10 years the field of mitochondrial genetics has widened, shifting the focus from rare sporadic, metabolic disease to the effects of mitochondrial DNA (mtDNA) variation in a growing spectrum of human disease. The aim of this review is to guide the reader through some key concepts regarding mitochondria before introducing both classic and emerging mitochondrial disorders. Sources of data In this article, a review of the current mitochondrial genetics literature was conducted using PubMed (http://www.ncbi.nlm.nih.gov/pubmed/). In addition, this review makes use of a growing number of publically available databases including MITOMAP, a human mitochondrial genome database (www.mitomap.org), the Human DNA polymerase Gamma Mutation Database (http://tools.niehs.nih.gov/polg/) and PhyloTree.org (www.phylotree.org), a repository of global mtDNA variation. Areas of agreement The disruption in cellular energy, resulting from defects in mtDNA or defects in the nuclear-encoded genes responsible for mitochondrial maintenance, manifests in a growing number of human diseases. Areas of controversy The exact mechanisms which govern the inheritance of mtDNA are hotly debated. Growing points Although still in the early stages, the development of in vitro genetic manipulation could see an end to the inheritance of the most severe mtDNA disease. PMID:23704099

  4. The Mitochondrial-Derived Peptide Humanin Protects RPE Cells From Oxidative Stress, Senescence, and Mitochondrial Dysfunction

    PubMed Central

    Sreekumar, Parameswaran G.; Ishikawa, Keijiro; Spee, Chris; Mehta, Hemal H.; Wan, Junxiang; Yen, Kelvin; Cohen, Pinchas; Kannan, Ram; Hinton, David R.

    2016-01-01

    Purpose To investigate the expression of humanin (HN) in human retinal pigment epithelial (hRPE) cells and its effect on oxidative stress–induced cell death, mitochondrial bioenergetics, and senescence. Methods Humanin localization in RPE cells and polarized RPE monolayers was assessed by confocal microscopy. Human RPE cells were treated with 150 μM tert-Butyl hydroperoxide (tBH) in the absence/presence of HN (0.5–10 μg/mL) for 24 hours. Mitochondrial respiration was measured by XF96 analyzer. Retinal pigment epithelial cell death and caspase-3 activation, mitochondrial biogenesis and senescence were analyzed by TUNEL, immunoblot analysis, mitochondrial DNA copy number, SA-β-Gal staining, and p16INK4a expression and HN levels by ELISA. Oxidative stress–induced changes in transepithelial resistance were studied in RPE monolayers with and without HN cotreatment. Results A prominent localization of HN was found in the cytoplasmic and mitochondrial compartments of hRPE. Humanin cotreatment inhibited tBH-induced reactive oxygen species formation and significantly restored mitochondrial bioenergetics in hRPE cells. Exogenous HN was taken up by RPE and colocalized with mitochondria. The oxidative stress–induced decrease in mitochondrial bioenergetics was prevented by HN cotreatment. Humanin treatment increased mitochondrial DNA copy number and upregulated mitochondrial transcription factor A, a key biogenesis regulator protein. Humanin protected RPE cells from oxidative stress–induced cell death by STAT3 phosphorylation and inhibiting caspase-3 activation. Humanin treatment inhibited oxidant-induced senescence. Polarized RPE demonstrated elevated cellular HN and increased resistance to cell death. Conclusions Humanin protected RPE cells against oxidative stress–induced cell death and restored mitochondrial function. Our data suggest a potential role for HN therapy in the prevention of retinal degeneration, including AMD. PMID:26990160

  5. Death Penalty in America.

    ERIC Educational Resources Information Center

    Clifford, Amie L.

    1997-01-01

    Examines the legal and moral issues, controversies, and unique trial procedures involved with the death penalty. Discusses the 1972 landmark Supreme Court decision that resulted in many states abolishing this punishment, only to reintroduce it later with different provisions. Reviews the controversial case of Sam Sheppard. (MJP)

  6. Mitochondrial Dysfunction in Neurodegenerative Diseases

    PubMed Central

    Johri, Ashu

    2012-01-01

    Neurodegenerative diseases are a large group of disabling disorders of the nervous system, characterized by the relative selective death of neuronal subtypes. In most cases, there is overwhelming evidence of impaired mitochondrial function as a causative factor in these diseases. More recently, evidence has emerged for impaired mitochondrial dynamics (shape, size, fission-fusion, distribution, movement etc.) in neurodegenerative diseases such as Parkinson's disease, Huntington's disease, amyotrophic lateral sclerosis, and Alzheimer's disease. Here, we provide a concise overview of the major findings in recent years highlighting the importance of healthy mitochondria for a healthy neuron. PMID:22700435

  7. Cot Deaths.

    ERIC Educational Resources Information Center

    Tyrrell, Shelagh

    1985-01-01

    Addresses the tragedy of crib deaths, giving particular attention to causes, prevention, and medical research on Sudden Infant Death Syndrome (SIDS). Gives anecdotal accounts of coping strategies used by parents and families of SIDS infants. (DT)

  8. Mitochondrial Metabolism in Aging Heart.

    PubMed

    Lesnefsky, Edward J; Chen, Qun; Hoppel, Charles L

    2016-05-13

    Altered mitochondrial metabolism is the underlying basis for the increased sensitivity in the aged heart to stress. The aged heart exhibits impaired metabolic flexibility, with a decreased capacity to oxidize fatty acids and enhanced dependence on glucose metabolism. Aging impairs mitochondrial oxidative phosphorylation, with a greater role played by the mitochondria located between the myofibrils, the interfibrillar mitochondria. With aging, there is a decrease in activity of complexes III and IV, which account for the decrease in respiration. Furthermore, aging decreases mitochondrial content among the myofibrils. The end result is that in the interfibrillar area, there is ≈50% decrease in mitochondrial function, affecting all substrates. The defective mitochondria persist in the aged heart, leading to enhanced oxidant production and oxidative injury and the activation of oxidant signaling for cell death. Aging defects in mitochondria represent new therapeutic targets, whether by manipulation of the mitochondrial proteome, modulation of electron transport, activation of biogenesis or mitophagy, or the regulation of mitochondrial fission and fusion. These mechanisms provide new ways to attenuate cardiac disease in elders by preemptive treatment of age-related defects, in contrast to the treatment of disease-induced dysfunction. PMID:27174952

  9. Mitochondrial Evolution

    PubMed Central

    Gray, Michael W.

    2012-01-01

    Viewed through the lens of the genome it contains, the mitochondrion is of unquestioned bacterial ancestry, originating from within the bacterial phylum α-Proteobacteria (Alphaproteobacteria). Accordingly, the endosymbiont hypothesis—the idea that the mitochondrion evolved from a bacterial progenitor via symbiosis within an essentially eukaryotic host cell—has assumed the status of a theory. Yet mitochondrial genome evolution has taken radically different pathways in diverse eukaryotic lineages, and the organelle itself is increasingly viewed as a genetic and functional mosaic, with the bulk of the mitochondrial proteome having an evolutionary origin outside Alphaproteobacteria. New data continue to reshape our views regarding mitochondrial evolution, particularly raising the question of whether the mitochondrion originated after the eukaryotic cell arose, as assumed in the classical endosymbiont hypothesis, or whether this organelle had its beginning at the same time as the cell containing it. PMID:22952398

  10. Mitochondrial dysfunction in amyotrophic lateral sclerosis - a valid pharmacological target?

    PubMed

    Muyderman, H; Chen, T

    2014-04-01

    Amyotrophic lateral sclerosis (ALS) is an adult-onset neurodegenerative disease characterized by the selective death of upper and lower motor neurons which ultimately leads to paralysis and ultimately death. Pathological changes in ALS are closely associated with pronounced and progressive changes in mitochondrial morphology, bioenergetics and calcium homeostasis. Converging evidence suggests that impaired mitochondrial function could be pivotal in the rapid neurodegeneration of this condition. In this review, we provide an update of recent advances in understanding mitochondrial biology in the pathogenesis of ALS and highlight the therapeutic value of pharmacologically targeting mitochondrial biology to slow disease progression.

  11. Potentiation of LPS-Induced Apoptotic Cell Death in Human Hepatoma HepG2 Cells by Aspirin via ROS and Mitochondrial Dysfunction: Protection by N-Acetyl Cysteine

    PubMed Central

    Raza, Haider; John, Annie; Shafarin, Jasmin

    2016-01-01

    Cytotoxicity and inflammation-associated toxic responses have been observed to be induced by bacterial lipopolysaccharides (LPS) in vitro and in vivo respectively. Use of nonsteroidal anti-inflammatory drugs (NSAIDs), such as aspirin, has been reported to be beneficial in inflammation-associated diseases like cancer, diabetes and cardiovascular disorders. Their precise molecular mechanisms, however, are not clearly understood. Our previous studies on aspirin treated HepG2 cells strongly suggest cell cycle arrest and induction of apoptosis associated with mitochondrial dysfunction. In the present study, we have further demonstrated that HepG2 cells treated with LPS alone or in combination with aspirin induces subcellular toxic responses which are accompanied by increase in reactive oxygen species (ROS) production, oxidative stress, mitochondrial respiratory dysfunction and apoptosis. The LPS/Aspirin induced toxicity was attenuated by pre-treatment of cells with N-acetyl cysteine (NAC). Alterations in oxidative stress and glutathione-dependent redox-homeostasis were more pronounced in mitochondria compared to extra- mitochondrial cellular compartments. Pre-treatment of HepG2 cells with NAC exhibited a selective protection in redox homeostasis and mitochondrial dysfunction. Our results suggest that the altered redox metabolism, oxidative stress and mitochondrial function in HepG2 cells play a critical role in LPS/aspirin-induced cytotoxicity. These results may help in better understanding the pharmacological, toxicological and therapeutic properties of NSAIDs in cancer cells exposed to bacterial endotoxins. PMID:27441638

  12. Mitochondrial control of nuclear apoptosis

    PubMed Central

    1996-01-01

    Anucleate cells can be induced to undergo programmed cell death (PCD), indicating the existence of a cytoplasmic PCD pathway that functions independently from the nucleus. Cytoplasmic structures including mitochondria have been shown to participate in the control of apoptotic nuclear disintegration. Before cells exhibit common signs of nuclear apoptosis (chromatin condensation and endonuclease-mediated DNA fragmentation), they undergo a reduction of the mitochondrial transmembrane potential (delta psi m) that may be due to the opening of mitochondrial permeability transition (PT) pores. Here, we present direct evidence indicating that mitochondrial PT constitutes a critical early event of the apoptotic process. In a cell-free system combining purified mitochondria and nuclei, mitochondria undergoing PT suffice to induce chromatin condensation and DNA fragmentation. Induction of PT by pharmacological agents augments the apoptosis-inducing potential of mitochondria. In contrast, prevention of PT by pharmacological agents impedes nuclear apoptosis, both in vitro and in vivo. Mitochondria from hepatocytes or lymphoid cells undergoing apoptosis, but not those from normal cells, induce disintegration of isolated Hela nuclei. A specific ligand of the mitochondrial adenine nucleotide translocator (ANT), bongkreik acid, inhibits PT and reduces apoptosis induction by mitochondria in a cell-free system. Moreover, it inhibits the induction of apoptosis in intact cells. Several pieces of evidence suggest that the proto-oncogene product Bcl-2 inhibits apoptosis by preventing mitochondrial PT. First, to inhibit nuclear apoptosis, Bcl-2 must be localized in mitochondrial but not nuclear membranes. Second, transfection-enforced hyperexpression of Bcl-2 directly abolishes the induction of mitochondrial PT in response to a protonophore, a pro- oxidant, as well as to the ANT ligand atractyloside, correlating with its apoptosis-inhibitory effect. In conclusion, mitochondrial PT appears

  13. Mitochondrial dysfunction and organophosphorus compounds

    SciTech Connect

    Karami-Mohajeri, Somayyeh; Abdollahi, Mohammad

    2013-07-01

    Organophosphorous (OPs) pesticides are the most widely used pesticides in the agriculture and home. However, many acute or chronic poisoning reports about OPs have been published in the recent years. Mitochondria as a site of cellular oxygen consumption and energy production can be a target for OPs poisoning as a non-cholinergic mechanism of toxicity of OPs. In the present review, we have reviewed and criticized all the evidences about the mitochondrial dysfunctions as a mechanism of toxicity of OPs. For this purpose, all biochemical, molecular, and morphological data were retrieved from various studies. Some toxicities of OPs are arisen from dysfunction of mitochondrial oxidative phosphorylation through alteration of complexes I, II, III, IV and V activities and disruption of mitochondrial membrane. Reductions of adenosine triphosphate (ATP) synthesis or induction of its hydrolysis can impair the cellular energy. The OPs disrupt cellular and mitochondrial antioxidant defense, reactive oxygen species generation, and calcium uptake and promote oxidative and genotoxic damage triggering cell death via cytochrome C released from mitochondria and consequent activation of caspases. The mitochondrial dysfunction induced by OPs can be restored by use of antioxidants such as vitamin E and C, alpha-tocopherol, electron donors, and through increasing the cytosolic ATP level. However, to elucidate many aspect of mitochondrial toxicity of Ops, further studies should be performed. - Highlights: • As a non-cholinergic mechanism of toxicity, mitochondria is a target for OPs. • OPs affect action of complexes I, II, III, IV and V in the mitochondria. • OPs reduce mitochondrial ATP. • OPs promote oxidative and genotoxic damage via release of cytochrome C from mitochondria. • OP-induced mitochondrial dysfunction can be restored by increasing the cytosolic ATP.

  14. Mitochondrial targeted β-lapachone induces mitochondrial dysfunction and catastrophic vacuolization in cancer cells.

    PubMed

    Ma, Jing; Lim, Chaemin; Sacher, Joshua R; Van Houten, Bennett; Qian, Wei; Wipf, Peter

    2015-11-01

    Mitochondria play important roles in tumor cell physiology and survival by providing energy and metabolites for proliferation and metastasis. As part of their oncogenic status, cancer cells frequently produce increased levels of mitochondrial-generated reactive oxygen species (ROS). However, extensive stimulation of ROS generation in mitochondria has been shown to be able to induce cancer cell death, and is one of the major mechanisms of action of many anticancer agents. We hypothesized that enhancing mitochondrial ROS generation through direct targeting of a ROS generator into mitochondria will exhibit tumor cell selectivity, as well as high efficacy in inducing cancer cell death. We thus synthesized a mitochondrial targeted version of β-lapachone (XJB-Lapachone) based on our XJB mitochondrial targeting platform. We found that the mitochondrial targeted β-lapachone is more efficient in inducing apoptosis compared to unconjugated β-lapachone, and the tumor cell selectivity is maintained. XJB-Lapachone also induced extensive cellular vacuolization and autophagy at a concentration not observed with unconjugated β-lapachone. Through characterization of mitochondrial function we revealed that XJB-Lapachone is indeed more capable of stimulating ROS generation in mitochondria, which led to a dramatic mitochondrial uncoupling and autophagic degradation of mitochondria. Taken together, we have demonstrated that targeting β-lapachone accomplishes higher efficacy through inducing ROS generation directly in mitochondria, resulting in extensive mitochondrial and cellular damage. XJB-Lapachone will thus help to establish a novel platform for the design of next generation mitochondrial targeted ROS generators for cancer therapy.

  15. Nanodelivery System for Mitochondrial Targeting

    NASA Astrophysics Data System (ADS)

    Yoong, Sia Lee; Pastorin, Giorgia

    2014-02-01

    Mitochondria are indispensable in cellular functions such as energy production and death execution. They are emerging as intriguing therapeutic target as their dysregulation was found to be monumental in diseases such as neurodegenerative disease, obesity, and cancer etc. Despite tremendous interest being focused on therapeutically intervening mitochondrial function, few mito-active drugs were successfully developed, particularly due to challenges in delivering active compound to this organelle. In this review, effort in utilizing nanotechnology for targeted mitochondrial delivery of compound is expounded based on the nature of the nanomaterial used. The advantage and potential offered are discussed alongside the limitation. Finally the review is concluded with perspectives of the application of nanocarrier in mitochondrial medicine, given the unresolved concern on potential complications.

  16. Altered Mitochondrial Dynamics and TBI Pathophysiology.

    PubMed

    Fischer, Tara D; Hylin, Michael J; Zhao, Jing; Moore, Anthony N; Waxham, M Neal; Dash, Pramod K

    2016-01-01

    Mitochondrial function is intimately linked to cellular survival, growth, and death. Mitochondria not only generate ATP from oxidative phosphorylation, but also mediate intracellular calcium buffering, generation of reactive oxygen species (ROS), and apoptosis. Electron leakage from the electron transport chain, especially from damaged or depolarized mitochondria, can generate excess free radicals that damage cellular proteins, DNA, and lipids. Furthermore, mitochondrial damage releases pro-apoptotic factors to initiate cell death. Previous studies have reported that traumatic brain injury (TBI) reduces mitochondrial respiration, enhances production of ROS, and triggers apoptotic cell death, suggesting a prominent role of mitochondria in TBI pathophysiology. Mitochondria maintain cellular energy homeostasis and health via balanced processes of fusion and fission, continuously dividing and fusing to form an interconnected network throughout the cell. An imbalance of these processes, particularly an excess of fission, can be detrimental to mitochondrial function, causing decreased respiration, ROS production, and apoptosis. Mitochondrial fission is regulated by the cytosolic GTPase, dynamin-related protein 1 (Drp1), which translocates to the mitochondrial outer membrane (MOM) to initiate fission. Aberrant Drp1 activity has been linked to excessive mitochondrial fission and neurodegeneration. Measurement of Drp1 levels in purified hippocampal mitochondria showed an increase in TBI animals as compared to sham controls. Analysis of cryo-electron micrographs of these mitochondria also showed that TBI caused an initial increase in the length of hippocampal mitochondria at 24 h post-injury, followed by a significant decrease in length at 72 h. Post-TBI administration of Mitochondrial division inhibitor-1 (Mdivi-1), a pharmacological inhibitor of Drp1, prevented this decrease in mitochondria length. Mdivi-1 treatment also reduced the loss of newborn neurons in the

  17. Altered Mitochondrial Dynamics and TBI Pathophysiology

    PubMed Central

    Fischer, Tara D.; Hylin, Michael J.; Zhao, Jing; Moore, Anthony N.; Waxham, M. Neal; Dash, Pramod K.

    2016-01-01

    Mitochondrial function is intimately linked to cellular survival, growth, and death. Mitochondria not only generate ATP from oxidative phosphorylation, but also mediate intracellular calcium buffering, generation of reactive oxygen species (ROS), and apoptosis. Electron leakage from the electron transport chain, especially from damaged or depolarized mitochondria, can generate excess free radicals that damage cellular proteins, DNA, and lipids. Furthermore, mitochondrial damage releases pro-apoptotic factors to initiate cell death. Previous studies have reported that traumatic brain injury (TBI) reduces mitochondrial respiration, enhances production of ROS, and triggers apoptotic cell death, suggesting a prominent role of mitochondria in TBI pathophysiology. Mitochondria maintain cellular energy homeostasis and health via balanced processes of fusion and fission, continuously dividing and fusing to form an interconnected network throughout the cell. An imbalance of these processes, particularly an excess of fission, can be detrimental to mitochondrial function, causing decreased respiration, ROS production, and apoptosis. Mitochondrial fission is regulated by the cytosolic GTPase, dynamin-related protein 1 (Drp1), which translocates to the mitochondrial outer membrane (MOM) to initiate fission. Aberrant Drp1 activity has been linked to excessive mitochondrial fission and neurodegeneration. Measurement of Drp1 levels in purified hippocampal mitochondria showed an increase in TBI animals as compared to sham controls. Analysis of cryo-electron micrographs of these mitochondria also showed that TBI caused an initial increase in the length of hippocampal mitochondria at 24 h post-injury, followed by a significant decrease in length at 72 h. Post-TBI administration of Mitochondrial division inhibitor-1 (Mdivi-1), a pharmacological inhibitor of Drp1, prevented this decrease in mitochondria length. Mdivi-1 treatment also reduced the loss of newborn neurons in the

  18. BDE-154 induces mitochondrial permeability transition and impairs mitochondrial bioenergetics.

    PubMed

    Pereira, Lílian Cristina; Miranda, Luiz Felippe Cabral; de Souza, Alecsandra Oliveira; Dorta, Daniel Junqueira

    2014-01-01

    Brominated flame retardants are used in various consumer goods to make these materials difficult to burn. Polybrominated diphenyl ethers (PBDE), which are representative of this class of retardants, consist of two benzene rings linked by an oxygen atom, and contain between 1 and 10 bromine atoms in their chemical structure, with the possibility of up to 209 different congeners. Among these congeners, BDE-154 (hexa-BDE) is persistent in the environment and easy to detect in the biota, but no apparent information regarding the mechanism underlying action and toxicity is available. Mitochondria, as the main energy-producing organelles, play an important role in the maintenance of various cellular functions. Therefore, mitochondria were used in the present study as an experimental model to determine the effects of BDE-154 congener at concentrations ranging from 0.1 μM to 50 μM. Our results demonstrated that BDE-154 interacts with the mitochondrial membrane, preferably by inserting into the hydrophobic core of the mitochondrial membrane, which partially inhibits respiration, dissipates Δψ, and permeabilizes the inner mitochondrial membrane to deplete ATP. These effects are more pronounced at concentrations equal to or higher than 10 μM. Results also showed that BDE-154 did not induce reactive oxygen species (ROS) accumulation within the mitochondria, indicating the absence of oxidative stress. Therefore, BDE-154 impairs mitochondrial bioenergetics and permeabilizes the mitochondrial membrane, potentially leading to cell death but not via mechanisms involving oxidative stress. PMID:24555644

  19. Mitochondrial Division and Fusion in Metabolism

    PubMed Central

    Roy, Madhuparna; Reddy, P. Hemachandra; Iijima, Miho; Sesaki, Hiromi

    2015-01-01

    Mitochondria govern many metabolic processes. In addition, mitochondria sense the status of metabolism and change their functions to regulate energy production, cell death, and thermogenesis. Recent studies have revealed that mitochondrial structural remodeling through division and fusion is critical to the organelle’s function. It has also become clear that abnormalities in mitochondrial division and fusion are linked to the pathophysiology of metabolic diseases such as diabetes and obesity. Here, we discuss the current understanding of the mechanisms of mitochondrial dynamics and their role in cellular and organismal metabolism. PMID:25703628

  20. Genetic and biochemical intricacy shapes mitochondrial cytopathies.

    PubMed

    Turnbull, Douglass M; Rustin, Pierre

    2016-08-01

    The major progress made in the identification of the molecular bases of mitochondrial disease has revealed the huge diversity of their origin. Today up to 300 mutations were identified in the mitochondrial genome and about 200 nuclear genes are possibly mutated. In this review, we highlight a number of features specific to mitochondria which possibly participate in the complexity of these diseases. These features include both the complexity of mitochondrial genetics and the multiplicity of the roles ensured by the organelles in numerous aspects of cell life and death. This spectacular complexity presumably accounts for the present lack of an efficient therapy in the vast majority of cases.

  1. A near death experience: Shigella manipulates host death machinery to silence innate immunity.

    PubMed

    Bronner, Denise N; O'Riordan, Mary Xd

    2014-10-01

    Release of mitochondrial contents often triggers inflammation and cell death, and modulating this process can be advantageous to invading pathogens. In this issue of The EMBO Journal, Andree and colleagues reveal new findings that an intracellular bacterial pathogen exploits apoptotic machinery to suppress host immune signaling, yet avoids cell death. This study emphasizes the need to expand our understanding of the roles played by pro‐apoptotic proteins in non‐death scenarios.

  2. OPA1 and mitochondrial solute carriers in bioenergetic metabolism

    PubMed Central

    Germain, Marc

    2015-01-01

    The mitochondrial fusion protein optic atrophy 1 (OPA1) is required to maintain cristae structure and for ATP synthase assembly. Our recent work demonstrates that OPA1 dynamically regulates these processes by sensing changes in nutrient availability through mitochondrial solute carriers and adjusting the metabolic output of mitochondria accordingly. This is a critical survival process as its inhibition leads to cell death. PMID:27308447

  3. Death duties

    PubMed Central

    Myers, Kathryn A.; Eden, David

    2007-01-01

    PROBLEM BEING ADDRESSED Family physicians are often called upon to pronounce and certify the deaths of patients. Inadequate knowledge of the Coroners Act (in the province of Ontario) and of the correct process of certifying death can make physicians uncomfortable when confronted with these tasks. OBJECTIVE OF PROGRAM To educate family physicians about how to perform the administrative tasks required of them when patients die. PROGRAM DESCRIPTION The program included an educational video, a tutorial outlining the process of death certification, and discussion with a regional coroner about key features of the Coroners Act. In small groups, participants worked through cases of patient deaths in which they were asked to determine whether a coroner needed to be involved, to determine the manner of death, and to complete a mock death certificate for each case. CONCLUSION All participants reported a high level of satisfaction with the workshop and thought the main objective of the program had been achieved. Results of a test given 3 months after the workshop showed substantial improvement in participants’ knowledge of the coroner’s role and of the process of death certification. PMID:17872782

  4. Hepatic mitochondrial glutathione: transport and role in disease and toxicity

    SciTech Connect

    Fernandez-Checa, Jose C. . E-mail: checa229@yahoo.com; Kaplowitz, Neil . E-mail: kaplowitz@hsc.usc.edu

    2005-05-01

    Synthesized in the cytosol of cells, a fraction of cytosolic glutathione (GSH) is then transported into the mitochondrial matrix where it reaches a high concentration and plays a critical role in defending mitochondria against oxidants and electrophiles. Evidence mainly from kidney and liver mitochondria indicated that the dicarboxylate and the 2-oxoglutarate carriers contribute to the transport of GSH across the mitochondrial inner membrane. However, differential features between kidney and liver mitochondrial GSH (mGSH) transport seem to suggest the existence of additional carriers the identity of which remains to be established. One of the characteristic features of the hepatic mitochondrial transport of GSH is its regulation by membrane fluidity. Conditions leading to increased cholesterol deposition in the mitochondrial inner membrane such as in alcohol-induced liver injury decrease membrane fluidity and impair the mitochondrial transport of GSH. Depletion of mitochondrial GSH by alcohol is believed to contribute to the sensitization of the liver to alcohol-induced injury through tumor necrosis factor (TNF)-mediated hepatocellular death. Through control of mitochondrial electron transport chain-generated oxidants, mitochondrial GSH modulates cell death and hence its regulation may be a key target to influence disease progression and drug-induced cell death.

  5. What Is Mitochondrial DNA?

    MedlinePlus

    ... DNA What is mitochondrial DNA? What is mitochondrial DNA? Although most DNA is packaged in chromosomes within ... proteins. For more information about mitochondria and mitochondrial DNA: Molecular Expressions, a web site from the Florida ...

  6. Mitochondrial dysfunction in uremic cardiomyopathy

    PubMed Central

    Taylor, David; Bhandari, Sunil

    2015-01-01

    Uremic cardiomyopathy (UCM) is characterized by metabolic remodelling, compromised energetics, and loss of insulin-mediated cardioprotection, which result in unsustainable adaptations and heart failure. However, the role of mitochondria and the susceptibility of mitochondrial permeability transition pore (mPTP) formation in ischemia-reperfusion injury (IRI) in UCM are unknown. Using a rat model of chronic uremia, we investigated the oxidative capacity of mitochondria in UCM and their sensitivity to ischemia-reperfusion mimetic oxidant and calcium stressors to assess the susceptibility to mPTP formation. Uremic animals exhibited a 45% reduction in creatinine clearance (P < 0.01), and cardiac mitochondria demonstrated uncoupling with increased state 4 respiration. Following IRI, uremic mitochondria exhibited a 58% increase in state 4 respiration (P < 0.05), with an overall reduction in respiratory control ratio (P < 0.01). Cardiomyocytes from uremic animals displayed a 30% greater vulnerability to oxidant-induced cell death determined by FAD autofluorescence (P < 0.05) and reduced mitochondrial redox state on exposure to 200 μM H2O2 (P < 0.01). The susceptibility to calcium-induced permeability transition showed that maximum rates of depolarization were enhanced in uremia by 79%. These results demonstrate that mitochondrial respiration in the uremic heart is chronically uncoupled. Cardiomyocytes in UCM are characterized by a more oxidized mitochondrial network, with greater susceptibility to oxidant-induced cell death and enhanced vulnerability to calcium-induced mPTP formation. Collectively, these findings indicate that mitochondrial function is compromised in UCM with increased vulnerability to calcium and oxidant-induced stressors, which may underpin the enhanced predisposition to IRI in the uremic heart. PMID:25587120

  7. Neonatal Death

    MedlinePlus

    ... story First Candle Centering Corporation The Compassionate Friends Star Legacy Foundation Last reviewed: November, 2015 Neonatal death ... story First Candle Centering Corporation The Compassionate Friends Star Legacy Foundation Last reviewed: November, 2015 Complications & Loss ...

  8. Mitochondrial calcium uniporter regulator 1 (MCUR1) regulates the calcium threshold for the mitochondrial permeability transition

    PubMed Central

    Artiga, Daniel J.; Abiria, Sunday A.; Clapham, David E.

    2016-01-01

    During the mitochondrial permeability transition, a large channel in the inner mitochondrial membrane opens, leading to the loss of multiple mitochondrial solutes and cell death. Key triggers include excessive reactive oxygen species and mitochondrial calcium overload, factors implicated in neuronal and cardiac pathophysiology. Examining the differential behavior of mitochondrial Ca2+ overload in Drosophila versus human cells allowed us to identify a gene, MCUR1, which, when expressed in Drosophila cells, conferred permeability transition sensitive to electrophoretic Ca2+ uptake. Conversely, inhibiting MCUR1 in mammalian cells increased the Ca2+ threshold for inducing permeability transition. The effect was specific to the permeability transition induced by Ca2+, and such resistance to overload translated into improved cell survival. Thus, MCUR1 expression regulates the Ca2+ threshold required for permeability transition. PMID:26976564

  9. Mitochondrial dysfunction and resuscitation in sepsis.

    PubMed

    Ruggieri, Albert J; Levy, Richard J; Deutschman, Clifford S

    2010-07-01

    Sepsis is among the most common causes of death in patients in intensive care units in North America and Europe. In the United States, it accounts for upwards of 250,000 deaths each year. Investigations into the pathobiology of sepsis have most recently focused on common cellular and subcellular processes. One possibility would be a defect in the production of energy, which translates to an abnormality in the production of adenosine triphosphate and therefore in the function of mitochondria. This article presents a clear role for mitochondrial dysfunction in the pathogenesis and pathophysiology of sepsis. What is less clear is the teleology underlying this response. Prolonged mitochondrial dysfunction and impaired biogenesis clearly are detrimental. However, early inhibition of mitochondrial function may be adaptive. PMID:20643307

  10. Mitochondrial and Postmitochondrial Survival Signaling in Cancer

    PubMed Central

    Yadav, Neelu; Chandra, Dhyan

    2014-01-01

    Cancer cells are resistant to conventional chemotherapy and radiotherapy, however, the molecular mechanisms of resistance to therapy remain unclear. Cellular survival machinery protects mitochondrial integrity against endogenous or exogenous stresses. Prodeath molecules orchestrate around mitochondria to initiate and execute cell death in cancer, and also play an under appreciated role in survival of cancer cells. Prosurvival mechanisms can operate at mitochondrial and postmitochondrial levels to attenuate core apoptotic death program. It is intriguing to explore how prosurvival and prodeath molecules crosstalk to regulate mitochondrial functions leading to increased cancer cell survival. This review describes some putative survival mechanisms at mitochondria, which may play significant role in designing effective agents for cancer prevention and therapy. These survival pathways may also have significance in understanding other human pathophysiological conditions including diabetes, cardiovascular, autoimmune, and neurodegenerative diseases. PMID:24333692

  11. CHCHD2 connects mitochondrial metabolism to apoptosis.

    PubMed

    Liu, Yong; Zhang, Yanping

    2015-01-01

    As the powerhouse of cells and gatekeeper for apoptosis, mitochondria control life and death. CHCHD2, a mitochondrial protein previously known to regulate metabolism, has recently been identified as an apoptosis inhibitor. New data suggest a model in which CHCHD2 performs a prosurvival function by acting as both a reactive oxygen species scavenger and BCL-XL activator. PMID:27308501

  12. Bcl-2 apoptosis proteins, mitochondrial membrane curvature, and cancer

    NASA Astrophysics Data System (ADS)

    Hwee Lai, Ghee; Schmidt, Nathan; Sanders, Lori; Mishra, Abhijit; Wong, Gerard; Ivashyna, Olena; Christenson, Eric; Schlesinger, Paul; Akabori, Kiyotaka; Santangelo, Christian

    2012-02-01

    Critical interactions between Bcl-2 family proteins permeabilize the outer mitochondrial membrane, a common decision point early in the intrinsic apoptotic pathway that irreversibly commits the cell to death. However, a unified picture integrating the essential non-passive role of lipid membranes with the contested dynamics of Bcl-2 regulation remains unresolved. Correlating results between synchrotron x-ray diffraction and microscopy in cell-free assays, we report activation of pro-apoptotic Bax induces strong pure negative Gaussian membrane curvature topologically necessary for pore formation and membrane remodeling events. Strikingly, Bcl-xL suppresses not only Bax-induced pore formation, but also membrane remodeling by disparate systems including cell penetrating, antimicrobial or viral fusion peptides, and bacterial toxin, none of which have BH3 allosteric domains to mediate direct binding. We propose a parallel mode of Bcl-2 pore regulation in which Bax and Bcl-xL induce antagonistic and mutually interacting Gaussian membrane curvatures. The universal nature of curvature-mediated interactions allows synergy with direct binding mechanisms, and potentially accounts for the Bcl-2 family modulation of mitochondrial fission/fusion dynamics.

  13. cAMP signalling meets mitochondrial compartments.

    PubMed

    Lefkimmiatis, Konstantinos

    2014-04-01

    Mitochondria are highly dynamic organelles comprising at least three distinct areas, the OMM (outer mitochondrial membrane), the IMS (intermembrane space) and the mitochondrial matrix. Physical compartmentalization allows these organelles to host different functional domains and therefore participate in a variety of important cellular actions such as ATP synthesis and programmed cell death. In a surprising homology, it is now widely accepted that the ubiquitous second messenger cAMP uses the same stratagem, compartmentalization, in order to achieve the characteristic functional pleiotropy of its pathway. Accumulating evidence suggests that all the main mitochondrial compartments contain segregated cAMP cascades; however, the regulatory properties and functional significance of such domains are not fully understood and often remain controversial issues. The present mini-review discusses our current knowledge of how the marriage between mitochondrial and cAMP compartmentalization is achieved and its effects on the biology of the cell. PMID:24646228

  14. Nitration of Hsp90 on Tyrosine 33 Regulates Mitochondrial Metabolism*

    PubMed Central

    Franco, Maria C.; Ricart, Karina C.; Gonzalez, Analía S.; Dennys, Cassandra N.; Nelson, Pascal A.; Janes, Michael S.; Mehl, Ryan A.; Landar, Aimee; Estévez, Alvaro G.

    2015-01-01

    Peroxynitrite production and tyrosine nitration are present in several pathological conditions, including neurodegeneration, stroke, aging, and cancer. Nitration of the pro-survival chaperone heat shock protein 90 (Hsp90) in position 33 and 56 induces motor neuron death through a toxic gain-of-function. Here we show that nitrated Hsp90 regulates mitochondrial metabolism independently of the induction of cell death. In PC12 cells, a small fraction of nitrated Hsp90 was located on the mitochondrial outer membrane and down-regulated mitochondrial membrane potential, oxygen consumption, and ATP production. Neither endogenous Hsp90 present in the homogenate nor unmodified and fully active recombinant Hsp90 was able to compete with the nitrated protein for the binding to mitochondria. Moreover, endogenous or recombinant Hsp90 did not prevent the decrease in mitochondrial activity but supported nitrated Hsp90 mitochondrial gain-of-function. Nitrotyrosine in position 33, but not in any of the other four tyrosine residues prone to nitration in Hsp90, was sufficient to down-regulate mitochondrial activity. Thus, in addition to induction of cell death, nitrated Hsp90 can also regulate mitochondrial metabolism, suggesting that depending on the cell type, distinct Hsp90 nitration states regulate different aspects of cellular metabolism. This regulation of mitochondrial homeostasis by nitrated Hsp90 could be of particular relevance in cancer cells. PMID:26085096

  15. Mitochondrial Dynamics and Mitochondrial Dysfunction in Diabetes.

    PubMed

    Wada, Jun; Nakatsuka, Atsuko

    2016-06-01

    The mitochondria are involved in active and dynamic processes, such as mitochondrial biogenesis, fission, fusion and mitophagy to maintain mitochondrial and cellular functions. In obesity and type 2 diabetes, impaired oxidation, reduced mitochondrial contents, lowered rates of oxidative phosphorylation and excessive reactive oxygen species (ROS) production have been reported. Mitochondrial biogenesis is regulated by various transcription factors such as peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α), peroxisome proliferator-activated receptors (PPARs), estrogen-related receptors (ERRs), and nuclear respiratory factors (NRFs). Mitochondrial fusion is promoted by mitofusin 1 (MFN1), mitofusin 2 (MFN2) and optic atrophy 1 (OPA1), while fission is governed by the recruitment of dynamin-related protein 1 (DRP1) by adaptor proteins such as mitochondrial fission factor (MFF), mitochondrial dynamics proteins of 49 and 51 kDa (MiD49 and MiD51), and fission 1 (FIS1). Phosphatase and tensin homolog (PTEN)-induced putative kinase 1 (PINK1) and PARKIN promote DRP1-dependent mitochondrial fission, and the outer mitochondrial adaptor MiD51 is required in DRP1 recruitment and PARKIN-dependent mitophagy. This review describes the molecular mechanism of mitochondrial dynamics, its abnormality in diabetes and obesity, and pharmaceuticals targeting mitochondrial biogenesis, fission, fusion and mitophagy. PMID:27339203

  16. Mitochondrial fragmentation in excitotoxicity requires ROCK activation.

    PubMed

    Martorell-Riera, Alejandro; Segarra-Mondejar, Marc; Reina, Manuel; Martínez-Estrada, Ofelia M; Soriano, Francesc X

    2015-01-01

    Mitochondria morphology constantly changes through fission and fusion processes that regulate mitochondrial function, and it therefore plays a prominent role in cellular homeostasis. Cell death progression is associated with mitochondrial fission. Fission is mediated by the mainly cytoplasmic Drp1, which is activated by different post-translational modifications and recruited to mitochondria to perform its function. Our research and other studies have shown that in the early moments of excitotoxic insult Drp1 must be nitrosylated to mediate mitochondrial fragmentation in neurons. Nonetheless, mitochondrial fission is a multistep process in which filamentous actin assembly/disassembly and myosin-mediated mitochondrial constriction play prominent roles. Here we establish that in addition to nitric oxide production, excitotoxicity-induced mitochondrial fragmentation also requires activation of the actomyosin regulator ROCK. Although ROCK1 has been shown to phosphorylate and activate Drp1, experiments using phosphor-mutant forms of Drp1 in primary cortical neurons indicate that in excitotoxic conditions, ROCK does not act directly on Drp1 to mediate fission, but may act on the actomyosin complex. Thus, these data indicate that a wider range of signaling pathways than those that target Drp1 are amenable to be inhibited to prevent mitochondrial fragmentation as therapeutic option. PMID:25789413

  17. Mitochondrial fragmentation in excitotoxicity requires ROCK activation.

    PubMed

    Martorell-Riera, Alejandro; Segarra-Mondejar, Marc; Reina, Manuel; Martínez-Estrada, Ofelia M; Soriano, Francesc X

    2015-01-01

    Mitochondria morphology constantly changes through fission and fusion processes that regulate mitochondrial function, and it therefore plays a prominent role in cellular homeostasis. Cell death progression is associated with mitochondrial fission. Fission is mediated by the mainly cytoplasmic Drp1, which is activated by different post-translational modifications and recruited to mitochondria to perform its function. Our research and other studies have shown that in the early moments of excitotoxic insult Drp1 must be nitrosylated to mediate mitochondrial fragmentation in neurons. Nonetheless, mitochondrial fission is a multistep process in which filamentous actin assembly/disassembly and myosin-mediated mitochondrial constriction play prominent roles. Here we establish that in addition to nitric oxide production, excitotoxicity-induced mitochondrial fragmentation also requires activation of the actomyosin regulator ROCK. Although ROCK1 has been shown to phosphorylate and activate Drp1, experiments using phosphor-mutant forms of Drp1 in primary cortical neurons indicate that in excitotoxic conditions, ROCK does not act directly on Drp1 to mediate fission, but may act on the actomyosin complex. Thus, these data indicate that a wider range of signaling pathways than those that target Drp1 are amenable to be inhibited to prevent mitochondrial fragmentation as therapeutic option.

  18. Mitochondrial biogenesis in plants during seed germination.

    PubMed

    Law, Simon R; Narsai, Reena; Whelan, James

    2014-11-01

    Mitochondria occupy a central role in the eukaryotic cell. In addition to being major sources of cellular energy, mitochondria are also involved in a diverse range of functions including signalling, the synthesis of many essential organic compounds and a role in programmed cell death. The active proliferation and differentiation of mitochondria is termed mitochondrial biogenesis and necessitates the coordinated communication of mitochondrial status within an integrated cellular network. Two models of mitochondrial biogenesis have been defined previously, the growth and division model and the maturation model. The former describes the growth and division of pre-existing mature organelles through a form of binary fission, while the latter describes the propagation of mitochondria from structurally and biochemically simple promitochondrial structures that upon appropriate stimuli, mature into fully functional mitochondria. In the last decade, a number of studies have utilised seed germination in plants as a platform for the examination of the processes occurring during mitochondrial biogenesis. These studies have revealed many new aspects of the tightly regulated procession of events that define mitochondrial biogenesis during this period of rapid development. A model for mitochondrial biogenesis that supports the maturation of mitochondria from promitochondrial structures has emerged, where mitochondrial signalling plays a crucial role in the early steps of seed germination. PMID:24727594

  19. Unraveling Biochemical Pathways Affected by Mitochondrial Dysfunctions Using Metabolomic Approaches

    PubMed Central

    Demine, Stéphane; Reddy, Nagabushana; Renard, Patricia; Raes, Martine; Arnould, Thierry

    2014-01-01

    Mitochondrial dysfunction(s) (MDs) can be defined as alterations in the mitochondria, including mitochondrial uncoupling, mitochondrial depolarization, inhibition of the mitochondrial respiratory chain, mitochondrial network fragmentation, mitochondrial or nuclear DNA mutations and the mitochondrial accumulation of protein aggregates. All these MDs are known to alter the capacity of ATP production and are observed in several pathological states/diseases, including cancer, obesity, muscle and neurological disorders. The induction of MDs can also alter the secretion of several metabolites, reactive oxygen species production and modify several cell-signalling pathways to resolve the mitochondrial dysfunction or ultimately trigger cell death. Many metabolites, such as fatty acids and derived compounds, could be secreted into the blood stream by cells suffering from mitochondrial alterations. In this review, we summarize how a mitochondrial uncoupling can modify metabolites, the signalling pathways and transcription factors involved in this process. We describe how to identify the causes or consequences of mitochondrial dysfunction using metabolomics (liquid and gas chromatography associated with mass spectrometry analysis, NMR spectroscopy) in the obesity and insulin resistance thematic. PMID:25257998

  20. Mitochondrial DNA determines androgen dependence in prostate cancer cell lines

    PubMed Central

    Higuchi, M; Kudo, T; Suzuki, S; Evans, TT; Sasaki, R; Wada, Y; Shirakawa, T; Sawyer, JR; Gotoh, A

    2008-01-01

    Prostate cancer progresses from an androgen-dependent to androgen-independent stage after androgen ablation therapy. Mitochondrial DNA plays a role in cell death and metastatic competence. Further, heteroplasmic large-deletion mitochondrial DNA is verycommon in prostate cancer. To investigate the role of mitochondrial DNA in androgen dependence of prostate cancers, we tested the changes of normal and deleted mitochondrial DNA in accordance with the progression of prostate cancer. We demonstrated that the androgen-independent cell line C4-2, established byinoculation of the androgen-dependent LNCaP cell line into castrated mice, has a greatlyreduced amount of normal mitochondrial DNA and an accumulation of large-deletion DNA. Strikingly, the depletion of mitochondrial DNA from androgen-dependent LNCaP resulted in a loss of androgen dependence. Reconstitution of normal mitochondrial DNA to the mitochondrial DNA-depleted clone restored androgen dependence. These results indicate that mitochondrial DNA determines androgen dependence of prostate cancer cell lines. Further, mitochondrial DNA-deficient cells formed tumors in castrated athymic mice, whereas LNCaP did not. The accumulation of large deletion and depletion of mitochondrial DNA maythus playa role in the development of androgen independence, leading to progression of prostate cancers. PMID:16278679

  1. Mitochondrial cytopathies and cardiovascular disease.

    PubMed

    Dominic, Elizabeth A; Ramezani, Ali; Anker, Stefan D; Verma, Mukesh; Mehta, Nehal; Rao, Madhumathi

    2014-04-01

    The global epidemic of cardiovascular disease remains the leading cause of death in the USA and across the world. Functional and structural integrity of mitochondria are essential for the physiological function of the cardiovascular system. The metabolic adaptation observed in normal heart is lost in the failing myocardium, which becomes progressively energy depleted leading to impaired myocardial contraction and relaxation. Uncoupling of electron transfer from ATP synthesis leads to excess generation of reactive species, leading to widespread cellular injury and cardiovascular disease. Accumulation of mitochondrial DNA mutation has been linked to ischaemic heart disease, cardiomyopathy and atherosclerotic vascular disease. Mitochondria are known to regulate apoptotic and autophagic pathways that have been shown to play an important role in the development of cardiomyopathy and atherosclerosis. A number of pharmacological and non-pharmacological treatment options have been explored in the management of mitochondrial diseases with variable success. PMID:24449718

  2. LHON: Mitochondrial Mutations and More

    PubMed Central

    Kirches, E

    2011-01-01

    Leber’s hereditary optic neuropathy (LHON) is a mitochondrial disorder leading to severe visual impairment or even blindness by death of retinal ganglion cells (RGCs). The primary cause of the disease is usually a mutation of the mitochondrial genome (mtDNA) causing a single amino acid exchange in one of the mtDNA-encoded subunits of NADH:ubiquinone oxidoreductase, the first complex of the electron transport chain. It was thus obvious to accuse neuronal energy depletion as the most probable mediator of neuronal death. The group of Valerio Carelli and other authors have nicely shown that energy depletion shapes the cell fate in a LHON cybrid cell model. However, the cybrids used were osteosarcoma cells, which do not fully model neuronal energy metabolism. Although complex I mutations may cause oxidative stress, a potential pathogenetic role of the latter was less taken into focus. The hypothesis of bioenergetic failure does not provide a simple explanation for the relatively late disease onset and for the incomplete penetrance, which differs remarkably between genders. It is assumed that other genetic and environmental factors are needed in addition to the ‘primary LHON mutations’ to elicit RGC death. Relevant nuclear modifier genes have not been identified so far. The review discusses the unresolved problems of a pathogenetic hypothesis based on ATP decline and/or ROS-induced apoptosis in RGCs. PMID:21886454

  3. LHON: Mitochondrial Mutations and More.

    PubMed

    Kirches, E

    2011-03-01

    Leber's hereditary optic neuropathy (LHON) is a mitochondrial disorder leading to severe visual impairment or even blindness by death of retinal ganglion cells (RGCs). The primary cause of the disease is usually a mutation of the mitochondrial genome (mtDNA) causing a single amino acid exchange in one of the mtDNA-encoded subunits of NADH:ubiquinone oxidoreductase, the first complex of the electron transport chain. It was thus obvious to accuse neuronal energy depletion as the most probable mediator of neuronal death. The group of Valerio Carelli and other authors have nicely shown that energy depletion shapes the cell fate in a LHON cybrid cell model. However, the cybrids used were osteosarcoma cells, which do not fully model neuronal energy metabolism. Although complex I mutations may cause oxidative stress, a potential pathogenetic role of the latter was less taken into focus. The hypothesis of bioenergetic failure does not provide a simple explanation for the relatively late disease onset and for the incomplete penetrance, which differs remarkably between genders. It is assumed that other genetic and environmental factors are needed in addition to the 'primary LHON mutations' to elicit RGC death. Relevant nuclear modifier genes have not been identified so far. The review discusses the unresolved problems of a pathogenetic hypothesis based on ATP decline and/or ROS-induced apoptosis in RGCs.

  4. Staphylococcus aureus Sepsis Induces Early Renal Mitochondrial DNA Repair and Mitochondrial Biogenesis in Mice

    PubMed Central

    Bartz, Raquel R.; Fu, Ping; Suliman, Hagir B.; Crowley, Stephen D.; MacGarvey, Nancy Chou; Welty-Wolf, Karen; Piantadosi, Claude A.

    2014-01-01

    Acute kidney injury (AKI) contributes to the high morbidity and mortality of multi-system organ failure in sepsis. However, recovery of renal function after sepsis-induced AKI suggests active repair of energy-producing pathways. Here, we tested the hypothesis in mice that Staphyloccocus aureus sepsis damages mitochondrial DNA (mtDNA) in the kidney and activates mtDNA repair and mitochondrial biogenesis. Sepsis was induced in wild-type C57Bl/6J and Cox-8 Gfp-tagged mitochondrial-reporter mice via intraperitoneal fibrin clots embedded with S. aureus. Kidneys from surviving mice were harvested at time zero (control), 24, or 48 hours after infection and evaluated for renal inflammation, oxidative stress markers, mtDNA content, and mitochondrial biogenesis markers, and OGG1 and UDG mitochondrial DNA repair enzymes. We examined the kidneys of the mitochondrial reporter mice for changes in staining density and distribution. S. aureus sepsis induced sharp amplification of renal Tnf, Il-10, and Ngal mRNAs with decreased renal mtDNA content and increased tubular and glomerular cell death and accumulation of protein carbonyls and 8-OHdG. Subsequently, mtDNA repair and mitochondrial biogenesis was evidenced by elevated OGG1 levels and significant increases in NRF-1, NRF-2, and mtTFA expression. Overall, renal mitochondrial mass, tracked by citrate synthase mRNA and protein, increased in parallel with changes in mitochondrial GFP-fluorescence especially in proximal tubules in the renal cortex and medulla. Sub-lethal S. aureus sepsis thus induces widespread renal mitochondrial damage that triggers the induction of the renal mtDNA repair protein, OGG1, and mitochondrial biogenesis as a conspicuous resolution mechanism after systemic bacterial infection. PMID:24988481

  5. PDT: death pathways

    NASA Astrophysics Data System (ADS)

    Kessel, David

    2007-02-01

    Cellular targets of photodynamic therapy include mitochondria, lysosomes, the endoplasmic reticulum (ER) and the plasma membrane. PDT can evoke necrosis, autophagy and apoptosis, or combinations of these, depending on the PDT dose, the site(s) of photodamage and the cellular phenotype. It has been established that loss of viability occurs even when the apoptotic program is inhibited. Studies assessing effects of ER or mitochondrial photodamage, involving loss of Bcl-2 function, indicate that low-dose PDT elicited a rapid autophagic response in L1210 cells. This was attributed to the ability of autophagy to recycle photodamaged organelles, and there was partial protection from loss of viability. This effect was not observed in L1210/Atg7, where autophagy was silenced. At higher PDT doses, apoptotic cells were observed within 60 min in both cell lines, but more so in L1210. The ability of L1210 cells to undergo autophagy did not offer protection from cell death at the higher PDT dose. Previous studies had indicated that autophagy can contribute to cell death, since L1210 cells that do not undergo an initial apoptotic response often contain multiple autophagic vacuoles 24 hr later. With L1210/Atg7, apoptosis alone may account for the loss of viability at an LD 90 PDT dose.

  6. Tantalizing Thanatos: unexpected links in death pathways.

    PubMed

    Cohen, Isabelle; Castedo, Maria; Kroemer, Guido

    2002-07-01

    Cell death is most frequently the result of apoptosis, an event that is often controlled by mitochondrial membrane permeabilization (MMP). Recent data reveal unexpected functional links between apoptosis and autophagic cell death, in the sense that MMP can trigger autophagy of damaged mitochondria. Conversely, one of the major signal-transducing molecules involved in the activation of autophagy during apoptosis--the so-called DAP kinase--can induce cell death through MMP. Connections are also emerging between apoptosis, autophagy, replicative senescence and cancer-specific metabolic changes. PMID:12185842

  7. Death Penalty Issues Following Atkins

    ERIC Educational Resources Information Center

    Patton, James R.; Keyes, Denis W.

    2006-01-01

    In light of the U.S. Supreme Court's 2002 landmark decision in "Atkins v. Virginia," a diagnosis of mild mental retardation has taken on a life and death significance for people who are the most deeply involved in criminal justice. As such, each aspect of the mental retardation definition (American Association on Mental Retardation, 2002) is a…

  8. Yeast as a tool to study signaling pathways in mitochondrial stress response and cytoprotection.

    PubMed

    Zdralević, Maša; Guaragnella, Nicoletta; Antonacci, Lucia; Marra, Ersilia; Giannattasio, Sergio

    2012-01-01

    Cell homeostasis results from the balance between cell capability to adapt or succumb to environmental stress. Mitochondria, in addition to supplying cellular energy, are involved in a range of processes deciding about cellular life or death. The crucial role of mitochondria in cell death is well recognized. Mitochondrial dysfunction has been associated with the death process and the onset of numerous diseases. Yet, mitochondrial involvement in cellular adaptation to stress is still largely unexplored. Strong interest exists in pharmacological manipulation of mitochondrial metabolism and signaling. The yeast Saccharomyces cerevisiae has proven a valuable model organism in which several intracellular processes have been characterized in great detail, including the retrograde response to mitochondrial dysfunction and, more recently, programmed cell death. In this paper we review experimental evidences of mitochondrial involvement in cytoprotection and propose yeast as a model system to investigate the role of mitochondria in the cross-talk between prosurvival and prodeath pathways. PMID:22454613

  9. Yeast as a Tool to Study Signaling Pathways in Mitochondrial Stress Response and Cytoprotection

    PubMed Central

    Ždralević, Maša; Guaragnella, Nicoletta; Antonacci, Lucia; Marra, Ersilia; Giannattasio, Sergio

    2012-01-01

    Cell homeostasis results from the balance between cell capability to adapt or succumb to environmental stress. Mitochondria, in addition to supplying cellular energy, are involved in a range of processes deciding about cellular life or death. The crucial role of mitochondria in cell death is well recognized. Mitochondrial dysfunction has been associated with the death process and the onset of numerous diseases. Yet, mitochondrial involvement in cellular adaptation to stress is still largely unexplored. Strong interest exists in pharmacological manipulation of mitochondrial metabolism and signaling. The yeast Saccharomyces cerevisiae has proven a valuable model organism in which several intracellular processes have been characterized in great detail, including the retrograde response to mitochondrial dysfunction and, more recently, programmed cell death. In this paper we review experimental evidences of mitochondrial involvement in cytoprotection and propose yeast as a model system to investigate the role of mitochondria in the cross-talk between prosurvival and prodeath pathways. PMID:22454613

  10. Therapeutically targeting mitochondrial redox signalling alleviates endothelial dysfunction in preeclampsia.

    PubMed

    McCarthy, Cathal; Kenny, Louise C

    2016-01-01

    Aberrant placentation generating placental oxidative stress is proposed to play a critical role in the pathophysiology of preeclampsia. Unfortunately, therapeutic trials of antioxidants have been uniformly disappointing. There is provisional evidence implicating mitochondrial dysfunction as a source of oxidative stress in preeclampsia. Here we provide evidence that mitochondrial reactive oxygen species mediates endothelial dysfunction and establish that directly targeting mitochondrial scavenging may provide a protective role. Human umbilical vein endothelial cells exposed to 3% plasma from women with pregnancies complicated by preeclampsia resulted in a significant decrease in mitochondrial function with a subsequent significant increase in mitochondrial superoxide generation compared to cells exposed to plasma from women with uncomplicated pregnancies. Real-time PCR analysis showed increased expression of inflammatory markers TNF-α, TLR-9 and ICAM-1 respectively in endothelial cells treated with preeclampsia plasma. MitoTempo is a mitochondrial-targeted antioxidant, pre-treatment of cells with MitoTempo protected against hydrogen peroxide-induced cell death. Furthermore MitoTempo significantly reduced mitochondrial superoxide production in cells exposed to preeclampsia plasma by normalising mitochondrial metabolism. MitoTempo significantly altered the inflammatory profile of plasma treated cells. These novel data support a functional role for mitochondrial redox signaling in modulating the pathogenesis of preeclampsia and identifies mitochondrial-targeted antioxidants as potential therapeutic candidates. PMID:27604418

  11. Therapeutically targeting mitochondrial redox signalling alleviates endothelial dysfunction in preeclampsia

    PubMed Central

    McCarthy, Cathal; Kenny, Louise C.

    2016-01-01

    Aberrant placentation generating placental oxidative stress is proposed to play a critical role in the pathophysiology of preeclampsia. Unfortunately, therapeutic trials of antioxidants have been uniformly disappointing. There is provisional evidence implicating mitochondrial dysfunction as a source of oxidative stress in preeclampsia. Here we provide evidence that mitochondrial reactive oxygen species mediates endothelial dysfunction and establish that directly targeting mitochondrial scavenging may provide a protective role. Human umbilical vein endothelial cells exposed to 3% plasma from women with pregnancies complicated by preeclampsia resulted in a significant decrease in mitochondrial function with a subsequent significant increase in mitochondrial superoxide generation compared to cells exposed to plasma from women with uncomplicated pregnancies. Real-time PCR analysis showed increased expression of inflammatory markers TNF-α, TLR-9 and ICAM-1 respectively in endothelial cells treated with preeclampsia plasma. MitoTempo is a mitochondrial-targeted antioxidant, pre-treatment of cells with MitoTempo protected against hydrogen peroxide-induced cell death. Furthermore MitoTempo significantly reduced mitochondrial superoxide production in cells exposed to preeclampsia plasma by normalising mitochondrial metabolism. MitoTempo significantly altered the inflammatory profile of plasma treated cells. These novel data support a functional role for mitochondrial redox signaling in modulating the pathogenesis of preeclampsia and identifies mitochondrial-targeted antioxidants as potential therapeutic candidates. PMID:27604418

  12. Novel insights into the mitochondrial permeability transition

    PubMed Central

    Bonora, Massimo; Bravo-San Pedro, José Manuel; Kroemer, Guido; Galluzzi, Lorenzo; Pinton, Paolo

    2014-01-01

    Alavian and colleagues recently provided further evidence in support of the notion that the c subunit of the mitochondrial F1FO ATP synthase constitutes the long-sought pore-forming unit of the supramolecular complex responsible for the so-called ‘mitochondrial permeability transition’ (MPT). Besides shedding new light on the molecular mechanisms that underlie the MPT, these findings corroborate the notion that several components of the cell death machinery, including cytochrome c and the F1FO ATP synthase, mediate critical metabolic activities. PMID:25486353

  13. The physiological role of mitochondrial calcium revealed by mice lacking the mitochondrial calcium uniporter.

    PubMed

    Pan, Xin; Liu, Jie; Nguyen, Tiffany; Liu, Chengyu; Sun, Junhui; Teng, Yanjie; Fergusson, Maria M; Rovira, Ilsa I; Allen, Michele; Springer, Danielle A; Aponte, Angel M; Gucek, Marjan; Balaban, Robert S; Murphy, Elizabeth; Finkel, Toren

    2013-12-01

    Mitochondrial calcium has been postulated to regulate a wide range of processes from bioenergetics to cell death. Here, we characterize a mouse model that lacks expression of the recently discovered mitochondrial calcium uniporter (MCU). Mitochondria derived from MCU(-/-) mice have no apparent capacity to rapidly uptake calcium. Whereas basal metabolism seems unaffected, the skeletal muscle of MCU(-/-) mice exhibited alterations in the phosphorylation and activity of pyruvate dehydrogenase. In addition, MCU(-/-) mice exhibited marked impairment in their ability to perform strenuous work. We further show that mitochondria from MCU(-/-) mice lacked evidence for calcium-induced permeability transition pore (PTP) opening. The lack of PTP opening does not seem to protect MCU(-/-) cells and tissues from cell death, although MCU(-/-) hearts fail to respond to the PTP inhibitor cyclosporin A. Taken together, these results clarify how acute alterations in mitochondrial matrix calcium can regulate mammalian physiology.

  14. Regulated cell death in AKI.

    PubMed

    Linkermann, Andreas; Chen, Guochun; Dong, Guie; Kunzendorf, Ulrich; Krautwald, Stefan; Dong, Zheng

    2014-12-01

    AKI is pathologically characterized by sublethal and lethal damage of renal tubules. Under these conditions, renal tubular cell death may occur by regulated necrosis (RN) or apoptosis. In the last two decades, tubular apoptosis has been shown in preclinical models and some clinical samples from patients with AKI. Mechanistically, apoptotic cell death in AKI may result from well described extrinsic and intrinsic pathways as well as ER stress. Central converging nodes of these pathways are mitochondria, which become fragmented and sensitized to membrane permeabilization in response to cellular stress, resulting in the release of cell death-inducing factors. Whereas apoptosis is known to be regulated, tubular necrosis was thought to occur by accident until recent work unveiled several RN subroutines, most prominently receptor-interacting protein kinase-dependent necroptosis and RN induced by mitochondrial permeability transition. Additionally, other cell death pathways, like pyroptosis and ferroptosis, may also be of pathophysiologic relevance in AKI. Combination therapy targeting multiple cell-death pathways may, therefore, provide maximal therapeutic benefits. PMID:24925726

  15. Glutathione in Cancer Cell Death

    PubMed Central

    Ortega, Angel L.; Mena, Salvador; Estrela, Jose M.

    2011-01-01

    Glutathione (L-γ-glutamyl-L-cysteinyl-glycine; GSH) in cancer cells is particularly relevant in the regulation of carcinogenic mechanisms; sensitivity against cytotoxic drugs, ionizing radiations, and some cytokines; DNA synthesis; and cell proliferation and death. The intracellular thiol redox state (controlled by GSH) is one of the endogenous effectors involved in regulating the mitochondrial permeability transition pore complex and, in consequence, thiol oxidation can be a causal factor in the mitochondrion-based mechanism that leads to cell death. Nevertheless GSH depletion is a common feature not only of apoptosis but also of other types of cell death. Indeed rates of GSH synthesis and fluxes regulate its levels in cellular compartments, and potentially influence switches among different mechanisms of death. How changes in gene expression, post-translational modifications of proteins, and signaling cascades are implicated will be discussed. Furthermore, this review will finally analyze whether GSH depletion may facilitate cancer cell death under in vivo conditions, and how this can be applied to cancer therapy. PMID:24212662

  16. Putting the pieces together: How is the mitochondrial pathway of apoptosis regulated in cancer and chemotherapy?

    PubMed Central

    2014-01-01

    In order to solve a jigsaw puzzle, one must first have the complete picture to logically connect the pieces. However, in cancer biology, we are still gaining an understanding of all the signaling pathways that promote tumorigenesis and how these pathways can be pharmacologically manipulated by conventional and targeted therapies. Despite not having complete knowledge of the mechanisms that cause cancer, the signaling networks responsible for cancer are becoming clearer, and this information is serving as a solid foundation for the development of rationally designed therapies. One goal of chemotherapy is to induce cancer cell death through the mitochondrial pathway of apoptosis. Within this review, we present the pathways that govern the cellular decision to undergo apoptosis as three distinct, yet connected puzzle pieces: (1) How do oncogene and tumor suppressor pathways regulate apoptosis upstream of mitochondria? (2) How does the B-cell lymphoma 2 (BCL-2) family influence tumorigenesis and chemotherapeutic responses? (3) How is post-mitochondrial outer membrane permeabilization (MOMP) regulation of cell death relevant in cancer? When these pieces are united, it is possible to appreciate how cancer signaling directly impacts upon the fundamental cellular mechanisms of apoptosis and potentially reveals novel pharmacological targets within these pathways that may enhance chemotherapeutic success. PMID:25621172

  17. Mitochondrial DNA inheritance after SCNT.

    PubMed

    Hiendleder, Stefan

    2007-01-01

    Mitochondrial biogenesis and function is under dual genetic control and requires extensive interaction between biparentally inherited nuclear genes and maternally inherited mitochondrial genes. Standard SCNT procedures deprive an oocytes' mitochondrial DNA (mtDNA) of the corresponding maternal nuclear DNA and require it to interact with an entirely foreign nucleus that is again interacting with foreign somatic mitochondria. As a result, most SCNT embryos, -fetuses, and -offspring carry somatic cell mtDNA in addition to recipient oocyte mtDNA, a condition termed heteroplasmy. It is thus evident that somatic cell mtDNA can escape the selective mechanism that targets and eliminates intraspecific sperm mitochondria in the fertilized oocyte to maintain homoplasmy. However, the factors responsible for the large intra- and interindividual differences in heteroplasmy level remain elusive. Furthermore, heteroplasmy is probably confounded with mtDNA recombination. Considering the essential roles of mitochondria in cellular metabolism, cell signalling, and programmed cell death, future experiments will need to assess the true extent and impact of unorthodox mtDNA transmission on various aspects of SCNT success.

  18. Behavioral science and the juvenile death penalty.

    PubMed

    Leong, G B; Eth, S

    1989-01-01

    Behavioral science data included in an amicus brief has been introduced into a recent Supreme Court decision (Thompson v. Oklahoma) involving the juvenile death penalty. However, a close examination of the data fails to provide support for either the pro- or antijuvenile death penalty position.

  19. Mitochondrial RNA granules: Compartmentalizing mitochondrial gene expression

    PubMed Central

    Jourdain, Alexis A.; Boehm, Erik; Maundrell, Kinsey

    2016-01-01

    In mitochondria, DNA replication, gene expression, and RNA degradation machineries coexist within a common nondelimited space, raising the question of how functional compartmentalization of gene expression is achieved. Here, we discuss the recently characterized “mitochondrial RNA granules,” mitochondrial subdomains with an emerging role in the regulation of gene expression. PMID:26953349

  20. Protective effect of FGF21 on type 1 diabetes-induced testicular apoptotic cell death probably via both mitochondrial- and endoplasmic reticulum stress-dependent pathways in the mouse model.

    PubMed

    Jiang, Xin; Zhang, Chi; Xin, Ying; Huang, Zhifeng; Tan, Yi; Huang, Yadong; Wang, Yonggang; Feng, Wenke; Li, Xiaokun; Li, Wei; Qu, Yaqin; Cai, Lu

    2013-05-10

    Fibroblast growth factor 21 (FGF21) is a novel member identified and was reported to express predominantly in pancreas, liver and adipose tissue, and relatively less in other organs, such as the testis. However, the role of FGF21 in the testis has never been addressed. The present study examined FGF21 expression at mRNA level by real-time RT-PCR assay in the testis of fasting and non-fasting mice or mice with type 1 diabetes that was induced with streptozotocin. We also examined the effect of Fgf21 gene deletion or supplementation of the exogenous FGF21 on the testicular apoptotic cell death spontaneously or induced by type 1 diabetes in FGF21 knockout (FGF21-KO) mice. Deletion of Fgf21 gene does not affect testicular cell proliferation, but significantly increases the spontaneous incidence of testicular TUNEL positive cells with increases in the Bax/Bcl2 expression ratio and apoptosis-inducing factor (AIF) expression. Diabetes induced significant increases in testicular TUNEL positive cells, Bax/Bcl2 expression ratio, AIF expression, CHOP and cleaved caspase-12 expression, and oxidative damage, but did not change the expression of cleaved caspase-3 and caspase-8. Deletion of Fgf21 gene also significantly enhances diabetes-induced TUNEL positive cells along with the increased expression of Bax/Bcl2 ratio, AIF, CHOP, cleaved caspase-12, and oxidative damage, which was significantly prevented by the supplementation of exogenous FGF21. These results suggest that Fgf21 gene may involve in maintaining normal spermatogenesis and also protect the germ cells from diabetes-induced apoptotic cell death probably via the prevention of diabetes-induced oxidative damage. PMID:23499715

  1. [Accompany death].

    PubMed

    Salvador Borrell, Montserrat

    2010-11-01

    One of the roles of nursing is to take care of the patients in terminal situation. The time, the experience, the formation, and the personal and professional attitudes that the nurse has will propitiate that taking care of moribund patients might turn into one of the more rewarding human experiences in life. There for, it is indispensable that nurses assume death as a natural and inevitable reality to achieve. The principal aim of the study is to evaluate the competence of confrontation and the autoefficiency of the welfare among nurses who work with adult patients at the end of the life. Descriptive study realized in the units of Oncology, Hametology and Palliative Care of the following centers: La Fe, Clínico, Dr. Peset, H. General, Arnau de Vilanova and Dr. Moliner de Portacoelli in Valencia (Spain). The following instruments were used: the Bugen Scale of confrontation of the Death (1980-1981) and the Robbins Scale of Autoefficiency (1992). Data suggests that major coping gives major autoeffciency and vice versa. The realized study opens numerous questions, specially related with training and the burden of preparation along the whole professional career, in order to achieve competence for coping and autoefficiency.

  2. Regulation of ceramide-induced neuronal death: cell metabolism meets neurodegeneration.

    PubMed

    Arboleda, Gonzalo; Morales, Luis Carlos; Benítez, Bruno; Arboleda, Humberto

    2009-03-01

    The present review explores the role of ceramides in neuronal apoptosis, as well as the recent discovery of the signaling pathways involved in this process placing particular emphasis on the correlation between cellular metabolism and neuronal death. Endogenous levels of ceramides are increased following various pro-apoptotic stimuli which have been identified as potential causes of chronic and acute neurodegenerative diseases. Ceramides induce changes in multiple enzymes and cell signaling components. The early inhibition of the neuronal survival pathway regulated by phosphatidil-inositol-3-kinase/protein kinase B or AKT mediated by ceramide may be a relevant early event in the decision of neuronal survival/death. It may perturb several molecular and metabolic functions. In particular it might decrease glycolysis through rapid modulation of hexokinase activity. This would in turn generate limited amounts of mitochondrial substrates leading to mitochondrial dysfunction and neuronal apoptosis. Subtle and early metabolic alterations caused by inhibition of the PI3K/AKT pathway mediated by ceramide may potentially work with genes associated with neurodegenerative diseases such as Parkinson's and Alzheimer's disease. Together they may be determinant steps in downstream events leading to neuronal apoptosis. Therefore, reinforcement of the PI3K/AKT pathway could constitute an important neuroprotective strategy.

  3. Religiosity and the construction of death in Turkish death announcements, 1970-2009.

    PubMed

    Ergin, Murat

    2012-03-01

    Death and rituals performed after death reflect and reproduce social distinctions despite death's popular reputation as a great leveler. This study examines expressions of religiosity and constructions of death in Turkish death announcements, paying particular attention to gendered, ethnic, and temporal variations as well as markers of status and cultural distinction. Death announcements in Turkey occupy a liminal position between obituaries and death notices: Unlike obituaries, no editorial decisions are involved in their publications. However, unlike death notices, Turkish announcements are venues for expressions of culturally scripted individual decisions. These large and decentralized collections of private decisions display rigid genre characteristics involving formulaic phrases but also change over time to reflect social, cultural, and economic changes in Turkish society. The present study focuses on a sample (N = 2,812) of death announcements in a major Turkish daily newspaper (Hürriyet) from 1970 to 2009. Results show that death announcements in Turkey increasingly rely on an emotional tone of loss and bereavement that replace constructions of death in a more detached and distant language and that religious and secular preferences in the language of announcements are an important domain in which cultural battles are fought and the participation patterns of new middle classes are negotiated.

  4. Arabidopsis ACCELERATED CELL DEATH2 modulates programmed cell death.

    PubMed

    Yao, Nan; Greenberg, Jean T

    2006-02-01

    The Arabidopsis thaliana chloroplast protein ACCELERATED CELL DEATH2 (ACD2) modulates the amount of programmed cell death (PCD) triggered by Pseudomonas syringae and protoporphyrin IX (PPIX) treatment. In vitro, ACD2 can reduce red chlorophyll catabolite, a chlorophyll derivative. We find that ACD2 shields root protoplasts that lack chlorophyll from light- and PPIX-induced PCD. Thus, chlorophyll catabolism is not obligatory for ACD2 anti-PCD function. Upon P. syringae infection, ACD2 levels and localization change in cells undergoing PCD and in their close neighbors. Thus, ACD2 shifts from being largely in chloroplasts to partitioning to chloroplasts, mitochondria, and, to a small extent, cytosol. ACD2 protects cells from PCD that requires the early mitochondrial oxidative burst. Later, the chloroplasts of dying cells generate NO, which only slightly affects cell viability. Finally, the mitochondria in dying cells have dramatically altered movements and cellular distribution. Overproduction of both ACD2 (localized to mitochondria and chloroplasts) and ascorbate peroxidase (localized to chloroplasts) greatly reduces P. syringae-induced PCD, suggesting a pro-PCD role for mitochondrial and chloroplast events. During infection, ACD2 may bind to and/or reduce PCD-inducing porphyrin-related molecules in mitochondria and possibly chloroplasts that generate reactive oxygen species, cause altered organelle behavior, and activate a cascade of PCD-inducing events.

  5. Invariant death

    PubMed Central

    Frank, Steven A.

    2016-01-01

    In nematodes, environmental or physiological perturbations alter death’s scaling of time. In human cancer, genetic perturbations alter death’s curvature of time. Those changes in scale and curvature follow the constraining contours of death’s invariant geometry. I show that the constraints arise from a fundamental extension to the theories of randomness, invariance and scale. A generalized Gompertz law follows. The constraints imposed by the invariant Gompertz geometry explain the tendency of perturbations to stretch or bend death’s scaling of time. Variability in death rate arises from a combination of constraining universal laws and particular biological processes. PMID:27785361

  6. Human Mitochondrial Protein Database

    National Institute of Standards and Technology Data Gateway

    SRD 131 Human Mitochondrial Protein Database (Web, free access)   The Human Mitochondrial Protein Database (HMPDb) provides comprehensive data on mitochondrial and human nuclear encoded proteins involved in mitochondrial biogenesis and function. This database consolidates information from SwissProt, LocusLink, Protein Data Bank (PDB), GenBank, Genome Database (GDB), Online Mendelian Inheritance in Man (OMIM), Human Mitochondrial Genome Database (mtDB), MITOMAP, Neuromuscular Disease Center and Human 2-D PAGE Databases. This database is intended as a tool not only to aid in studying the mitochondrion but in studying the associated diseases.

  7. Involvement of the mitochondrial compartment in human NCL fibroblasts

    SciTech Connect

    Pezzini, Francesco; Gismondi, Floriana; Tessa, Alessandra; Tonin, Paola; Carrozzo, Rosalba; Mole, Sara E.; Santorelli, Filippo M.; Simonati, Alessandro

    2011-12-09

    Highlights: Black-Right-Pointing-Pointer Mitochondrial reticulum fragmentation occurs in human CLN1 and CLN6 fibroblasts. Black-Right-Pointing-Pointer Likewise mitochondrial shift-to periphery and decreased mitochondrial density are seen. Black-Right-Pointing-Pointer Enhanced caspase-mediated apoptosis occurs following STS treatment in CLN1 fibroblasts. -- Abstract: Neuronal ceroid lipofuscinosis (NCL) are a group of progressive neurodegenerative disorders of childhood, characterized by the endo-lysosomal storage of autofluorescent material. Impaired mitochondrial function is often associated with neurodegeneration, possibly related to the apoptotic cascade. In this study we investigated the possible effects of lysosomal accumulation on the mitochondrial compartment in the fibroblasts of two NCL forms, CLN1 and CLN6. Fragmented mitochondrial reticulum was observed in all cells by using the intravital fluorescent marker Mitotracker, mainly in the perinuclear region. This was also associated with intense signal from the lysosomal markers Lysotracker and LAMP2. Likewise, mitochondria appeared to be reduced in number and shifted to the cell periphery by electron microscopy; moreover the mitochondrial markers VDCA and COX IV were reduced following quantitative Western blot analysis. Whilst there was no evidence of increased cell death under basal condition, we observed a significant increase in apoptotic nuclei following Staurosporine treatment in CLN1 cells only. In conclusion, the mitochondrial compartment is affected in NCL fibroblasts invitro, and CLN1 cells seem to be more vulnerable to the negative effects of stressed mitochondrial membrane than CLN6 cells.

  8. Cytoprotection by the Modulation of Mitochondrial Electron Transport Chain: The Emerging Role of Mitochondrial STAT3

    PubMed Central

    Szczepanek, Karol; Chen, Qun; Larner, Andrew C.; Lesnefsky, Edward J.

    2011-01-01

    The down regulation of mitochondrial electron transport is an emerging mechanism of cytoprotective intervention that is effective in pathologic settings such as myocardial ischemia and reperfusion when the continuation of mitochondrial respiration produces reactive oxygen species, mitochondrial calcium overload, and the release of cytochrome c to activate cell death programs. The initial target of deranged electron transport is the mitochondria themselves. In the first part of this review, we describe this concept and summarize different approaches used to regulate mitochondrial respiration by targeting complex I as a proximal site in the electron transport chain (ETC) in order to favor the cytoprotection. The second part of the review highlights the emerging role of signal transducer and activator of transcription 3 (STAT3) in the direct, non-transcriptional regulation of ETC, as an example of a genetic approach to modulate respiration. Recent studies indicate that a pool of STAT3 resides in the mitochondria where it is necessary for the maximal activity of complexes I and II of the electron transport chain (ETC). The over expression of mitochondrial-targeted STAT3 results in a partial blockade of electron transport at complexes I and II that does not impair mitochondrial membrane potential nor enhance the production of reactive oxygen species (ROS). The targeting of transcriptionally-inactive STAT3 to mitochondria attenuates damage to mitochondria during cell stress, resulting in decreased production of ROS and retention of cytochrome c by mitochondria. The overexpression of STAT3 targeted to mitochondria unveils a novel protective approach mediated by modulation of mitochondrial respiration that is independent of STAT3 transcriptional activity. The limitation of mitochondrial respiration under pathologic circumstances can be approached by activation and over expression of endogenous signaling mechanisms in addition to pharmacologic means. The regulation of

  9. Mitochondrial apoptosis: killing cancer using the enemy within

    PubMed Central

    Lopez, J; Tait, S W G

    2015-01-01

    Apoptotic cell death inhibits oncogenesis at multiple stages, ranging from transformation to metastasis. Consequently, in order for cancer to develop and progress, apoptosis must be inhibited. Cell death also plays major roles in cancer treatment, serving as the main effector function of many anti-cancer therapies. In this review, we discuss the role of apoptosis in the development and treatment of cancer. Specifically, we focus upon the mitochondrial pathway of apoptosis—the most commonly deregulated form of cell death in cancer. In this process, mitochondrial outer membrane permeabilisation or MOMP represents the defining event that irrevocably commits a cell to die. We provide an overview of how this pathway is regulated by BCL-2 family proteins and describe ways in which cancer cells can block it. Finally, we discuss exciting new approaches aimed at specifically inducing mitochondrial apoptosis in cancer cells, outlining their potential pitfalls, while highlighting their considerable therapeutic promise. PMID:25742467

  10. Regulated Cell Death in AKI

    PubMed Central

    Chen, Guochun; Dong, Guie; Kunzendorf, Ulrich; Krautwald, Stefan

    2014-01-01

    AKI is pathologically characterized by sublethal and lethal damage of renal tubules. Under these conditions, renal tubular cell death may occur by regulated necrosis (RN) or apoptosis. In the last two decades, tubular apoptosis has been shown in preclinical models and some clinical samples from patients with AKI. Mechanistically, apoptotic cell death in AKI may result from well described extrinsic and intrinsic pathways as well as ER stress. Central converging nodes of these pathways are mitochondria, which become fragmented and sensitized to membrane permeabilization in response to cellular stress, resulting in the release of cell death–inducing factors. Whereas apoptosis is known to be regulated, tubular necrosis was thought to occur by accident until recent work unveiled several RN subroutines, most prominently receptor-interacting protein kinase–dependent necroptosis and RN induced by mitochondrial permeability transition. Additionally, other cell death pathways, like pyroptosis and ferroptosis, may also be of pathophysiologic relevance in AKI. Combination therapy targeting multiple cell-death pathways may, therefore, provide maximal therapeutic benefits. PMID:24925726

  11. Encountering Death: Structured Activities for Death Awareness.

    ERIC Educational Resources Information Center

    Welch, Ira David; And Others

    This book is intended to be used as a supplement to standard textbooks on death and dying for college students. Chapter 1 "Encountering Death in the Self" builds the foundation for increased self-awareness for the study of death and dying. Chapter 2 "Encountering Death in the Family" provides activities which are appropriate for a wide variety of…

  12. The life and death of a B cell.

    PubMed

    Defrance, Thierry; Casamayor-Pallejà, Montserrat; Krammer, Peter H

    2002-01-01

    Regulation of apoptosis in the B cell lineage has implications for homeostasis, quality control of the antibody response, and tolerance. In this chapter we examine the different checkpoints that control life and death decisions of B cells during the antigen-independent and antigen-dependent phases of their development. We discuss the cell death mechanism involved in elimination of unwanted B cells at different stages of their development as well as the signals that trigger or repress the apoptotic process. At the steady state, before or after development of an immune response, B cell apoptosis ensures that the antigen receptor (BCR) on newly produced B cells is functional and does not recognize self-antigens with high avidity. It also ensures that the size of the peripheral B cell compartment remains constant in spite of the continuous input of B cells from the bone marrow. All these processes are controlled by the mitochondrial death pathway and are thus perturbed by overexpression of the antiapoptotic members of the bcl-2 gene family. By contrast, the death receptor pathway plays a prominent role during the antigen-dependent phase of B cell development. Three sets of membrane molecules stand as crucial regulators of B cell survival. First, the BCR which plays a central but ambiguous role. On the one hand, it triggers death of B cells that recognize self-antigens or have been exposed to repeated antigenic stimulations. On the other hand, it promotes survival of the peripheral mature B cell pool and protects activated B cells from CD95-induced killing. Second, the death receptor Fas/CD95 which is instrumental in censoring B cells activated in a bystander fashion at the initiation of the response to T-dependent antigens. It also drives elimination of low-affinity and self-reactive B cell clones that arise through the process of somatic mutations during the germinal center reaction. As such, it contributes to the affinity maturation of the antibody response. Finally

  13. The Mitochondrial Calcium Uniporter controls skeletal muscle trophism in vivo

    PubMed Central

    Mammucari, Cristina; Gherardi, Gaia; Zamparo, Ilaria; Raffaello, Anna; Boncompagni, Simona; Chemello, Francesco; Cagnin, Stefano; Braga, Alessandra; Zanin, Sofia; Pallafacchina, Giorgia; Zentilin, Lorena; Sandri, Marco; De Stefani, Diego; Protasi, Feliciano; Lanfranchi, Gerolamo; Rizzuto, Rosario

    2015-01-01

    Summary Muscle atrophy contributes to the poor prognosis of many pathophysiological conditions, but pharmacological therapies are still limited. Muscle activity leads to major swings in mitochondrial [Ca2+] which control aerobic metabolism, cell death and survival pathways. We have investigated in vivo the effects of mitochondrial Ca2+ homeostasis in skeletal muscle function and trophism, by overexpressing or silencing the Mitochondrial Calcium Uniporter (MCU). The results demonstrate that both in developing and in adult muscles MCU-dependent mitochondrial Ca2+ uptake has a marked trophic effect that does not depend on aerobic control, but impinges on two major hypertrophic pathways of skeletal muscle, PGC-1α4 and IGF1-AKT/PKB. In addition, MCU overexpression protects from denervation-induced atrophy. These data reveal a novel Ca2+-dependent organelle-to-nucleus signaling route, which links mitochondrial function to the control of muscle mass and may represent a possible pharmacological target in conditions of muscle loss. PMID:25732818

  14. LHON and other optic nerve atrophies: the mitochondrial connection.

    PubMed

    Howell, Neil

    2003-01-01

    The clinical, biochemical and genetic features of Leber's hereditary optic neuropathy (LHON) are reviewed. The etiology of LHON is complex, but the primary risk factor is a mutation in one of the seven mitochondrial genes that encode subunits of respiratory chain complex I. The pathogenesis of LHON is not yet understood, but one plausible model is that increased or altered mitochondrial ROS production renders the retinal ganglion cells vulnerable to apoptotic cell death. In addition to LHON, there are a large number of other optic nerve degenerative disorders including autosomal dominant optic atrophy, the toxic/nutritional optic neuropathies and glaucoma. A review of the recent scientific literature suggests that these disorders also involve mitochondrial dysfunction or altered mitochondrial signaling pathways in their pathogenesis. This mitochondrial link provides new avenues of experimental investigation to these major causes of loss of vision.

  15. The mitochondrial calcium uniporter (MCU): molecular identity and physiological roles.

    PubMed

    Patron, Maria; Raffaello, Anna; Granatiero, Veronica; Tosatto, Anna; Merli, Giulia; De Stefani, Diego; Wright, Lauren; Pallafacchina, Giorgia; Terrin, Anna; Mammucari, Cristina; Rizzuto, Rosario

    2013-04-12

    The direct measurement of mitochondrial [Ca(2+)] with highly specific probes demonstrated that major swings in organellar [Ca(2+)] parallel the changes occurring in the cytosol and regulate processes as diverse as aerobic metabolism and cell death by necrosis and apoptosis. Despite great biological relevance, insight was limited by the complete lack of molecular understanding. The situation has changed, and new perspectives have emerged following the very recent identification of the mitochondrial Ca(2+) uniporter, the channel allowing rapid Ca(2+) accumulation across the inner mitochondrial membrane.

  16. Mitochondrial dysfunction in blood cells from amyotrophic lateral sclerosis patients.

    PubMed

    Ehinger, Johannes K; Morota, Saori; Hansson, Magnus J; Paul, Gesine; Elmér, Eskil

    2015-06-01

    Mitochondrial dysfunction is implicated in amyotrophic lateral sclerosis, where the progressive degeneration of motor neurons results in muscle atrophy, paralysis and death. Abnormalities in both central nervous system and muscle mitochondria have previously been demonstrated in patient samples, indicating systemic disease. In this case-control study, venous blood samples were acquired from 24 amyotrophic lateral sclerosis patients and 21 age-matched controls. Platelets and peripheral blood mononuclear cells were isolated and mitochondrial oxygen consumption measured in intact and permeabilized cells with additions of mitochondrial substrates, inhibitors and titration of an uncoupler. Respiratory values were normalized to cell count and for two markers of cellular mitochondrial content, citrate synthase activity and mitochondrial DNA, respectively. Mitochondrial function was correlated with clinical staging of disease severity. Complex IV (cytochrome c-oxidase)-activity normalized to mitochondrial content was decreased in platelets from amyotrophic lateral sclerosis patients both when normalized to citrate synthase activity and mitochondrial DNA copy number. In mononuclear cells, complex IV-activity was decreased when normalized to citrate synthase activity. Mitochondrial content was increased in amyotrophic lateral sclerosis patient platelets. In mononuclear cells, complex I activity declined and mitochondrial content increased progressively with advancing disease stage. The findings are, however, based on small subsets of patients and need to be confirmed. We conclude that when normalized to mitochondria-specific content, complex IV-activity is reduced in blood cells from amyotrophic lateral sclerosis patients and that there is an apparent compensatory increase in cellular mitochondrial content. This supports systemic involvement in amyotrophic lateral sclerosis and suggests further study of mitochondrial function in blood cells as a future biomarker for the

  17. New insights into the role of mitochondria in aging: mitochondrial dynamics and more

    PubMed Central

    Seo, Arnold Y.; Joseph, Anna-Maria; Dutta, Debapriya; Hwang, Judy C. Y.; Aris, John P.; Leeuwenburgh, Christiaan

    2010-01-01

    A decline in mitochondrial function plays a key role in the aging process and increases the incidence of age-related disorders. A deeper understanding of the intricate nature of mitochondrial dynamics, which is described as the balance between mitochondrial fusion and fission, has revealed that functional and structural alterations in mitochondrial morphology are important factors in several key pathologies associated with aging. Indeed, a recent wave of studies has demonstrated the pleiotropic role of fusion and fission proteins in numerous cellular processes, including mitochondrial metabolism, redox signaling, the maintenance of mitochondrial DNA and cell death. Additionally, mitochondrial fusion and fission, together with autophagy, have been proposed to form a quality-maintenance mechanism that facilitates the removal of damaged mitochondria from the cell, a process that is particularly important to forestall aging. Thus, dysfunctional regulation of mitochondrial dynamics might be one of the intrinsic causes of mitochondrial dysfunction, which contributes to oxidative stress and cell death during the aging process. In this Commentary, we discuss recent studies that have converged at a consensus regarding the involvement of mitochondrial dynamics in key cellular processes, and introduce a possible link between abnormal mitochondrial dynamics and aging. PMID:20940129

  18. Mitochondrial biology: From molecules to diseases.

    PubMed

    Kabekkodu, Shama Prasada; Chakrabarty, Sanjiban; Shukla, Vaibhav; Varghese, Vinay Koshy; Singh, Keshav K; Thangaraj, Kumarasamy; Satyamoorthy, Kapaettu

    2015-09-01

    As an integral part of the cell, mitochondria play a pivotal role in the regulation of energy metabolism, signaling pathways, cell differentiation, cell proliferation and cell death. Mitochondrion with its own genetic material has characteristics distinct from those of the nuclear counterpart and its dysregulation is associated with a myriad of diseases. The discovery of interplay between the nuclear and mitochondrial genes, and various post-transcriptional modifications associated with their products has added excitement in the field. This has led to a better understanding of the basic mitochondrial function in normal and disease states, and is important for diagnosis and prognosis of a large number of disorders. The Fourth Annual Conference of Society for Mitochondrial Research and Medicine - India (SMRM) was titled "Mitochondrial Biology: from Molecules to Disease". The conference was organized by K. Satyamoorthy and K. Thangaraj at School of Life Sciences, Manipal University, Manipal, India, during 8-9 December, 2014. The aim of the conference was to bring researchers and clinicians to a common platform; create an opportunity for networking between laboratories; and to discuss about the recent development in mitochondrial biology, diagnosis, and therapy. This review summarizes the key outcomes of the conference.

  19. Mitochondrial Regulation of Cell Cycle and Proliferation

    PubMed Central

    Antico Arciuch, Valeria Gabriela; Elguero, María Eugenia; Poderoso, Juan José

    2012-01-01

    Abstract Eukaryotic mitochondria resulted from symbiotic incorporation of α-proteobacteria into ancient archaea species. During evolution, mitochondria lost most of the prokaryotic bacterial genes and only conserved a small fraction including those encoding 13 proteins of the respiratory chain. In this process, many functions were transferred to the host cells, but mitochondria gained a central role in the regulation of cell proliferation and apoptosis, and in the modulation of metabolism; accordingly, defective organelles contribute to cell transformation and cancer, diabetes, and neurodegenerative diseases. Most cell and transcriptional effects of mitochondria depend on the modulation of respiratory rate and on the production of hydrogen peroxide released into the cytosol. The mitochondrial oxidative rate has to remain depressed for cell proliferation; even in the presence of O2, energy is preferentially obtained from increased glycolysis (Warburg effect). In response to stress signals, traffic of pro- and antiapoptotic mitochondrial proteins in the intermembrane space (B-cell lymphoma-extra large, Bcl-2-associated death promoter, Bcl-2 associated X-protein and cytochrome c) is modulated by the redox condition determined by mitochondrial O2 utilization and mitochondrial nitric oxide metabolism. In this article, we highlight the traffic of the different canonical signaling pathways to mitochondria and the contributions of organelles to redox regulation of kinases. Finally, we analyze the dynamics of the mitochondrial population in cell cycle and apoptosis. Antioxid. Redox Signal. 16, 1150–1180. PMID:21967640

  20. Oxidative stress, mitochondrial dysfunction and the mitochondria theory of aging.

    PubMed

    Kong, Yahui; Trabucco, Sally E; Zhang, Hong

    2014-01-01

    Aging is characterized by a progressive decline in cellular function, organismal fitness and increased risk of age-associated diseases and death. One potential cause of aging is the progressive accumulation of dysfunctional mitochondria and oxidative damage with age. Considerable efforts have been made in our understanding of the role of mitochondrial dysfunction and oxidative stress in aging and age-associated diseases. This chapter outlines the interplay between oxidative stress and mitochondrial dysfunction, and discusses their impact on senescence, cell death, stem cell function, age-associated diseases and longevity.

  1. A cryptic mitochondrial targeting motif in Atg4D links caspase cleavage with mitochondrial import and oxidative stress

    PubMed Central

    Betin, Virginie M.S.; MacVicar, Thomas D.B.; Parsons, Stephen F.; Anstee, David J.; Lane, Jon D.

    2012-01-01

    The Atg4 cysteine proteases play crucial roles in the processing of Atg8 proteins during autophagy, but their regulation during cellular stress and differentiation remains poorly understood. We have found that two Atg4 family members—Atg4C and Atg4D—contain cryptic mitochondrial targeting sequences immediately downstream of their canonical (DEVD) caspase cleavage sites. Consequently, caspase-cleaved Atg4D (ΔN63 Atg4D) localizes to the mitochondrial matrix when expressed in mammalian cells, where it undergoes further processing to a ~42 kDa mitochondrial form. Interestingly, caspase cleavage is not needed for Atg4D mitochondrial import, because ~42 kDa mitochondrial Atg4D is observed in cells treated with caspase inhibitors and in cells expressing caspase-resistant Atg4D (DEVA63). Using HeLa cell lines stably expressing ΔN63 Atg4D, we showed that mitochondrial Atg4D sensitizes cells to cell death in the presence of the mitochondrial uncoupler, CCCP, and that mitochondrial cristae are less extensive in these cells. We further showed that the organization of mitochondrial cristae is altered during the mitochondrial clearance phase in differentiating primary human erythroblasts stably expressing ΔN63 Atg4D, and that these cells have elevated levels of mitochondrial reactive oxygen species (ROS) during late stages of erythropoiesis. Together these data suggest that the import of Atg4D during cellular stress and differentiation may play important roles in the regulation of mitochondrial physiology, ROS, mitophagy and cell viability. PMID:22441018

  2. Low-dose ionizing radiation induces mitochondrial fusion and increases expression of mitochondrial complexes I and III in hippocampal neurons

    PubMed Central

    Chang, Chuang-Rung; Kao, Mou-Chieh; Chen, Kuan-Wei; Chiu, Shih-Che; Hsu, Ming-Ling; Hsiang, I-Chou; Chen, Yu-Jen; Chen, Linyi

    2015-01-01

    High energy ionizing radiation can cause DNA damage and cell death. During clinical radiation therapy, the radiation dose could range from 15 to 60 Gy depending on targets. While 2 Gy radiation has been shown to cause cancer cell death, studies also suggest a protective potential by low dose radiation. In this study, we examined the effect of 0.2-2 Gy radiation on hippocampal neurons. Low dose 0.2 Gy radiation treatment increased the levels of MTT. Since hippocampal neurons are post-mitotic, this result reveals a possibility that 0.2 Gy irradiation may increase mitochondrial activity to cope with stimuli. Maintaining neural plasticity is an energy-demanding process that requires high efficient mitochondrial function. We thus hypothesized that low dose radiation may regulate mitochondrial dynamics and function to ensure survival of neurons. Our results showed that five days after 0.2 Gy irradiation, no obvious changes on neuronal survival, neuronal synapses, membrane potential of mitochondria, reactive oxygen species levels, and mitochondrial DNA copy numbers. Interestingly, 0.2 Gy irradiation promoted the mitochondria fusion, resulting in part from the increased level of a mitochondrial fusion protein, Mfn2, and inhibition of Drp1 fission protein trafficking to the mitochondria. Accompanying with the increased mitochondrial fusion, the expressions of complexes I and III of the electron transport chain were also increased. These findings suggest that, hippocampal neurons undergo increased mitochondrial fusion to modulate cellular activity as an adaptive mechanism in response to low dose radiation. PMID:26415228

  3. Programmed Cell Death During Caenorhabditis elegans Development.

    PubMed

    Conradt, Barbara; Wu, Yi-Chun; Xue, Ding

    2016-08-01

    Programmed cell death is an integral component of Caenorhabditis elegans development. Genetic and reverse genetic studies in C. elegans have led to the identification of many genes and conserved cell death pathways that are important for the specification of which cells should live or die, the activation of the suicide program, and the dismantling and removal of dying cells. Molecular, cell biological, and biochemical studies have revealed the underlying mechanisms that control these three phases of programmed cell death. In particular, the interplay of transcriptional regulatory cascades and networks involving multiple transcriptional regulators is crucial in activating the expression of the key death-inducing gene egl-1 and, in some cases, the ced-3 gene in cells destined to die. A protein interaction cascade involving EGL-1, CED-9, CED-4, and CED-3 results in the activation of the key cell death protease CED-3, which is tightly controlled by multiple positive and negative regulators. The activation of the CED-3 caspase then initiates the cell disassembly process by cleaving and activating or inactivating crucial CED-3 substrates; leading to activation of multiple cell death execution events, including nuclear DNA fragmentation, mitochondrial elimination, phosphatidylserine externalization, inactivation of survival signals, and clearance of apoptotic cells. Further studies of programmed cell death in C. elegans will continue to advance our understanding of how programmed cell death is regulated, activated, and executed in general. PMID:27516615

  4. Hepatocyte Death: A Clear and Present Danger

    PubMed Central

    MALHI, HARMEET; GUICCIARDI, MARIA EUGENIA; GORES, GREGORY J.

    2010-01-01

    The hepatocyte is especially vulnerable to injury due to its central role in xenobiotic metabolism including drugs and alcohol, participation in lipid and fatty acid metabolism, its unique role in the enterohepatic circulation of bile acids, the widespread prevalence of hepatotropic viruses, and its existence within a milieu of innate immune responding cells. Apoptosis and necrosis are the most widely recognized forms of hepatocyte cell death. The hepatocyte displays many unique features regarding cell death by apoptosis. It is quite susceptible to death receptor-mediated injury, and its death receptor signaling pathways involve the mitochondrial pathway for efficient cell killing. Also, death receptors can trigger lysosomal disruption in hepatocytes which further promote cell and tissue injury. Interestingly, hepatocytes are protected from cell death by only two anti-apoptotic proteins, Bcl-xL and Mcl-1, which have nonredundant functions. Endoplasmic reticulum stress or the unfolded protein response contributes to hepatocyte cell death during alterations of lipid and fatty acid metabolism. Finally, the current information implicating RIP kinases in necrosis provides an approach to more fully address this mode of cell death in hepatocyte injury. All of these processes contributing to hepatocyte injury are discussed in the context of potential therapeutic strategies. PMID:20664081

  5. Early events induced by the toxin deoxynivalenol lead to programmed cell death in Nicotiana tabacum cells.

    PubMed

    Yekkour, Amine; Tran, Daniel; Arbelet-Bonnin, Delphine; Briand, Joël; Mathieu, Florence; Lebrihi, Ahmed; Errakhi, Rafik; Sabaou, Nasserdine; Bouteau, François

    2015-09-01

    Deoxynivalenol (DON) is a mycotoxin affecting animals and plants. This toxin synthesized by Fusarium culmorum and Fusarium graminearum is currently believed to play a decisive role in the fungal phytopathogenesis as a virulence factor. Using cultured cells of Nicotiana tabacum BY2, we showed that DON-induced programmed cell death (PCD) could require transcription and translation processes, in contrast to what was observed in animal cells. DON could induce different cross-linked pathways involving (i) reactive oxygen species (ROS) generation linked, at least partly, to a mitochondrial dysfunction and a transcriptional down-regulation of the alternative oxidase (Aox1) gene and (ii) regulation of ion channel activities participating in cell shrinkage, to achieve PCD.

  6. Rape, race, and the death penalty in Georgia.

    PubMed

    Wolfgang, M E; Riedel, M

    1975-07-01

    Following the 1972 Supreme Court decision on capital punishment, the Georgia legislature enacted a death penalty statute that attempts to avoid constitutional objections by establishing discretionary death sentencing for 361 rape cases in Georgia, comparing legal and nonlegal variables. Results indicate that blacks convicted of raping whites were disproportionately sentenced to death.

  7. Carbon monoxide and mitochondria—modulation of cell metabolism, redox response and cell death

    PubMed Central

    Almeida, Ana S.; Figueiredo-Pereira, Cláudia; Vieira, Helena L. A.

    2015-01-01

    Carbon monoxide (CO) is an endogenously produced gasotransmitter, which is associated with cytoprotection and cellular homeostasis in several distinct cell types and tissues. CO mainly targets mitochondria because: (i) mitochondrial heme-proteins are the main potential candidates for CO to bind, (ii) many CO's biological actions are dependent on mitochondrial ROS signaling and (iii) heme is generated in the mitochondrial compartment. Mitochondria are the key cell energy factory, producing ATP through oxidative phosphorylation and regulating cell metabolism. These organelles are also implicated in many cell signaling pathways and the production of reactive oxygen species (ROS). Finally, mitochondria contain several factors activating programmed cell death pathways, which are released from the mitochondrial inter-membrane space upon mitochondrial membrane permeabilization. Therefore, disclosing CO mode of action at mitochondria opens avenues for deeper understanding CO's biological properties. Herein, it is discussed how CO affects the three main aspects of mitochondrial modulation of cell function: metabolism, redox response and cell death. PMID:25709582

  8. Mitochondrial Dysfunction Meets Senescence.

    PubMed

    Gallage, Suchira; Gil, Jesús

    2016-03-01

    Cellular senescence and mitochondrial dysfunction are hallmarks of ageing, but until now their relationship has not been clear. Recent work by Wiley et al. shows that mitochondrial defects can cause a distinct senescence phenotype termed MiDAS (mitochondrial dysfunction-associated senescence). MiDAS has a specific secretome that is able to drive some of the aging phenotypes. These findings suggest novel therapeutic opportunities for treating age-related pathologies. PMID:26874922

  9. MYC and Mitochondrial Biogenesis

    PubMed Central

    Morrish, Fionnuala; Hockenbery, David

    2014-01-01

    Mitochondria, the powerhouses of the cell, face two imperatives concerning biogenesis. The first is the requirement for dividing cells to replicate their mitochondrial content by growth of existing mitochondria. The second is the dynamic regulation of mitochondrial content in response to organismal and cellular cues (e.g., exercise, caloric restriction, energy status, temperature). MYC provides the clearest example of a programmed expansion of mitochondrial content linked to the cell cycle. As an oncogene, MYC also presents intriguing questions about the role of its mitochondrial targets in cancer-related phenotypes, such as the Warburg effect and MYC-dependent apoptosis. PMID:24789872

  10. Mitochondrial Approaches to Protect Against Cardiac Ischemia and Reperfusion Injury

    PubMed Central

    Camara, Amadou K. S.; Bienengraeber, Martin; Stowe, David F.

    2011-01-01

    The mitochondrion is a vital component in cellular energy metabolism and intracellular signaling processes. Mitochondria are involved in a myriad of complex signaling cascades regulating cell death vs. survival. Importantly, mitochondrial dysfunction and the resulting oxidative and nitrosative stress are central in the pathogenesis of numerous human maladies including cardiovascular diseases, neurodegenerative diseases, diabetes, and retinal diseases, many of which are related. This review will examine the emerging understanding of the role of mitochondria in the etiology and progression of cardiovascular diseases and will explore potential therapeutic benefits of targeting the organelle in attenuating the disease process. Indeed, recent advances in mitochondrial biology have led to selective targeting of drugs designed to modulate or manipulate mitochondrial function, to the use of light therapy directed to the mitochondrial function, and to modification of the mitochondrial genome for potential therapeutic benefit. The approach to rationally treat mitochondrial dysfunction could lead to more effective interventions in cardiovascular diseases that to date have remained elusive. The central premise of this review is that if mitochondrial abnormalities contribute to the etiology of cardiovascular diseases (e.g., ischemic heart disease), alleviating the mitochondrial dysfunction will contribute to mitigating the severity or progression of the disease. To this end, this review will provide an overview of our current understanding of mitochondria function in cardiovascular diseases as well as the potential role for targeting mitochondria with potential drugs or other interventions that lead to protection against cell injury. PMID:21559063

  11. A necrotic cell death model in a protist.

    PubMed

    Laporte, C; Kosta, A; Klein, G; Aubry, L; Lam, D; Tresse, E; Luciani, M F; Golstein, P

    2007-02-01

    While necrotic cell death is attracting considerable interest, its molecular bases are still poorly understood. Investigations in simple biological models, taken for instance outside the animal kingdom, may benefit from less interference from other cell death mechanisms and from better experimental accessibility, while providing phylogenetic information. Can necrotic cell death occur outside the animal kingdom? In the protist Dictyostelium, developmental stimuli induced in an autophagy mutant a stereotyped sequence of events characteristic of necrotic cell death. This sequence included swift mitochondrial uncoupling with mitochondrial 2',7'-dichlorofluorescein diacetate fluorescence, ATP depletion and increased oxygen consumption. This was followed by perinuclear clustering of dilated mitochondria. Rapid plasma membrane rupture then occurred, which was evidenced by time-lapse videos and quantified by FACS. Of additional interest, developmental stimuli and classical mitochondrial uncouplers triggered a similar sequence of events, and exogenous glucose delayed plasma membrane rupture in a nonglycolytic manner. The occurrence of necrotic cell death in the protist Dictyostelium (1) provides a very favorable model for further study of this type of cell death, and (2) strongly suggests that the mechanism underlying necrotic cell death was present in an ancestor common to the Amoebozoa protists and to animals and has been conserved in evolution.

  12. Death Education and Death Fear Reduction

    ERIC Educational Resources Information Center

    Mueller, Mary Louise

    1976-01-01

    The study examined the possibility of reducing the fear of death in early adolescents through a 12-lesson unit designed to assist the student to achieve an attitude of integration toward life and death. (NQ)

  13. Vimar Is a Novel Regulator of Mitochondrial Fission through Miro

    PubMed Central

    Ding, Lianggong; Han, Yanping; Li, Yuhong; Ji, Xunming; Liu, Lei

    2016-01-01

    As fundamental processes in mitochondrial dynamics, mitochondrial fusion, fission and transport are regulated by several core components, including Miro. As an atypical Rho-like small GTPase with high molecular mass, the exchange of GDP/GTP in Miro may require assistance from a guanine nucleotide exchange factor (GEF). However, the GEF for Miro has not been identified. While studying mitochondrial morphology in Drosophila, we incidentally observed that the loss of vimar, a gene encoding an atypical GEF, enhanced mitochondrial fission under normal physiological conditions. Because Vimar could co-immunoprecipitate with Miro in vitro, we speculated that Vimar might be the GEF of Miro. In support of this hypothesis, a loss-of-function (LOF) vimar mutant rescued mitochondrial enlargement induced by a gain-of-function (GOF) Miro transgene; whereas a GOF vimar transgene enhanced Miro function. In addition, vimar lost its effect under the expression of a constitutively GTP-bound or GDP-bound Miro mutant background. These results indicate a genetic dependence of vimar on Miro. Moreover, we found that mitochondrial fission played a functional role in high-calcium induced necrosis, and a LOF vimar mutant rescued the mitochondrial fission defect and cell death. This result can also be explained by vimar's function through Miro, because Miro’s effect on mitochondrial morphology is altered upon binding with calcium. In addition, a PINK1 mutant, which induced mitochondrial enlargement and had been considered as a Drosophila model of Parkinson’s disease (PD), caused fly muscle defects, and the loss of vimar could rescue these defects. Furthermore, we found that the mammalian homolog of Vimar, RAP1GDS1, played a similar role in regulating mitochondrial morphology, suggesting a functional conservation of this GEF member. The Miro/Vimar complex may be a promising drug target for diseases in which mitochondrial fission and fusion are dysfunctional. PMID:27716788

  14. Mitochondria: the headquarters in ischemia-induced neuronal death.

    PubMed

    Jordan, Joaquin; de Groot, Piet W J; Galindo, Maria F

    2011-06-01

    Due to a lack of efficient treatments, searching for novel therapies against acute ischemic stroke represents one of the main fields in neuropharmacology. In this review we summarize and discuss the role of mitochondrial participation in ischemia-induced neuronal death. Mitochondria are regarded as the main link between cellular stress signals and the execution of programmed death of nerve cells. Since it was described that the release of mitochondrial proteins such as cytochrome c, apoptosis inducing factor and endonuclease G are key elements in cell death pathways, they have been the focus of cell death studies. Changes in the permeability of the mitochondrial outer membrane result in a non-reversible step in cell death processes. Cytochrome c released from mitochondria binds in the cytoplasm to Apaf-1 to initiate the formation of an apoptosome, which then binds pro-caspase-9. Active caspase-9 cleaves "executioner" caspases, which in turn proceed to cleave key substrates in the cell. Thus, the identification of new targets might enable establishment of novel strategies for therapeutic research, in this case based on the molecular mechanisms of mitochondrial pathways, to improve the development of compounds for treatment of ischemia.

  15. Sudden infant death syndrome

    MedlinePlus

    Crib death; SIDS ... However, SIDS is still a major cause of death in infants under 1 year old. Thousands of ... affects boys more often than girls. Most SIDS deaths occur in the winter. The following may increase ...

  16. Death: 'nothing' gives insight.

    PubMed

    Ettema, Eric J

    2013-08-01

    According to a widely accepted belief, we cannot know our own death--death means 'nothing' to us. At first sight, the meaning of 'nothing' just implies the negation or absence of 'something'. Death then simply refers to the negation or absence of life. As a consequence, however, death has no meaning of itself. This leads to an ontological paradox in which death is both acknowledged and denied: death is … nothing. In this article, I investigate whether insight into the ontological paradox of the nothingness of death can contribute to a good end-of-life. By analysing Aquinas', Heidegger's and Derrida's understanding of death as nothingness, I explore how giving meaning to death on different ontological levels connects to, and at the same time provides resistance against, the harsh reality of death. By doing so, I intend to demonstrate that insight into the nothingness of death can count as a framework for a meaningful dealing with death.

  17. Twin Mitochondrial Sequence Analysis.

    PubMed

    Bouhlal, Yosr; Martinez, Selena; Gong, Henry; Dumas, Kevin; Shieh, Joseph T C

    2013-09-01

    When applying genome-wide sequencing technologies to disease investigation, it is increasingly important to resolve sequence variation in regions of the genome that may have homologous sequences. The human mitochondrial genome challenges interpretation given the potential for heteroplasmy, somatic variation, and homologous nuclear mitochondrial sequences (numts). Identical twins share the same mitochondrial DNA (mtDNA) from early life, but whether the mitochondrial sequence remains similar is unclear. We compared an adult monozygotic twin pair using high throughput-sequencing and evaluated variants with primer extension and mitochondrial pre-enrichment. Thirty-seven variants were shared between the twin individuals, and the variants were verified on the original genomic DNA. These studies support highly identical genetic sequence in this case. Certain low-level variant calls were of high quality and homology to the mitochondrial DNA, and they were further evaluated. When we assessed calls in pre-enriched mitochondrial DNA templates, we found that these may represent numts, which can be differentiated from mtDNA variation. We conclude that twin identity extends to mitochondrial DNA, and it is critical to differentiate between numts and mtDNA in genome sequencing, particularly since significant heteroplasmy could influence genome interpretation. Further studies on mtDNA and numts will aid in understanding how variation occurs and persists. PMID:24040623

  18. Clinical mitochondrial genetics

    PubMed Central

    Chinnery, P.; Howell, N.; Andrews, R.; Turnbull, D.

    1999-01-01

    The last decade has been an age of enlightenment as far as mitochondrial pathology is concerned. Well established nuclear genetic diseases, such as Friedreich's ataxia,12 Wilson disease,3 and autosomal recessive hereditary spastic paraplegia,4 have been shown to have a mitochondrial basis, and we are just starting to unravel the complex nuclear genetic disorders which directly cause mitochondrial dysfunction (table 1). However, in addition to the 3 billion base pair nuclear genome, each human cell typically contains thousands of copies of a small, 16.5 kb circular molecule of double stranded DNA (fig 1). Mitochondrial DNA (mtDNA) accounts for only 1% of the total cellular nucleic acid content. It encodes for 13 polypeptides which are essential for aerobic metabolism and defects of the mitochondrial genome are an important cause of human disease.9293 Since the characterisation of the first pathogenic mtDNA defects in 1988,513 over 50 point mutations and well over 100 rearrangements of the mitochondrial genome have been associated with human disease9495 (http://www.gen.emory.edu/mitomap.html). These disorders form the focus of this article.


Keywords: mitochondrial DNA; mitochondrial disease; heteroplasmy; genetic counselling PMID:10874629

  19. Mitochondrial Therapeutics for Cardioprotection

    PubMed Central

    Carreira, Raquel S.; Lee, Pamela; Gottlieb, Roberta A.

    2013-01-01

    Mitochondria represent approximately one-third of the mass of the heart and play a critical role in maintaining cellular function—however, they are also a potent source of free radicals and pro-apoptotic factors. As such, maintaining mitochondrial homeostasis is essential to cell survival. As the dominant source of ATP, continuous quality control is mandatory to ensure their ongoing optimal function. Mitochondrial quality control is accomplished by the dynamic interplay of fusion, fission, autophagy, and mitochondrial biogenesis. This review examines these processes in the heart and considers their role in the context of ischemia-reperfusion injury. Interventions that modulate mitochondrial turnover, including pharmacologic agents, exercise, and caloric restriction are discussed as a means to improve mitochondrial quality control, ameliorate cardiovascular dysfunction, and enhance longevity. PMID:21718247

  20. MITOCHONDRIAL GLUTATHIONE: FEATURES, REGULATION AND ROLE IN DISEASE

    PubMed Central

    Marí, Montserrat; Morales, Albert; Colell, Anna; García-Ruiz, Carmen; Kaplowitz, Neil; Fernández-Checa, José C

    2012-01-01

    BACKGROUND Mitochondria are the powerhouse of mammalian cells and the main source of reactive oxygen species (ROS) associated with oxygen consumption. In addition, they also play a strategic role in controlling the fate of cells through regulation of death pathways. Mitochondrial ROS production fulfills a signaling role through regulation of redox pathways, but also contributes to mitochondrial damage in a number of pathological states. SCOPE OF REVIEW Mitochondria are exposed to the constant generation of oxidant species, and yet the organelle remains functional due to the existence of an armamentarium of antioxidant defense systems aimed to repair oxidative damage, of which mitochondrial glutathione (mGSH) is of particular relevance. Thus, the aim of the review is to cover the regulation of mGSH and its role in disease. MAJOR CONCLUSIONS Cumulating evidence over recent years has demonstrated the essential role for mGSH in mitochondrial physiology and disease. Despite its high concentration in the mitochondrial matrix, mitochondria lack the enzymes to synthesize GSH de novo, so that mGSH originates from cytosolic GSH via transport through specific mitochondrial carriers, which exhibit sensitivity to membrane dynamics. Depletion of mGSH sensitizes cells to stimuli leading to oxidative stress such as TNF, hypoxia or amyloid β-peptide, thereby contributing to disease pathogenesis. GENERAL SIGNIFICANCE Understanding the regulation of mGSH may provide novel insights to disease pathogenesis and toxicity and the opportunity to design therapeutic targets of intervention in cell death susceptibility and disease. PMID:23123815

  1. Mitochondrial aquaporin-8 knockdown in human hepatoma HepG2 cells causes ROS-induced mitochondrial depolarization and loss of viability

    SciTech Connect

    Marchissio, Maria Julia; Francés, Daniel Eleazar Antonio; Carnovale, Cristina Ester; Marinelli, Raúl Alberto

    2012-10-15

    Human aquaporin-8 (AQP8) channels facilitate the diffusional transport of H{sub 2}O{sub 2} across membranes. Since AQP8 is expressed in hepatic inner mitochondrial membranes, we studied whether mitochondrial AQP8 (mtAQP8) knockdown in human hepatoma HepG2 cells impairs mitochondrial H{sub 2}O{sub 2} release, which may lead to organelle dysfunction and cell death. We confirmed AQP8 expression in HepG2 inner mitochondrial membranes and found that 72 h after cell transfection with siRNAs targeting two different regions of the human AQP8 molecule, mtAQP8 protein specifically decreased by around 60% (p < 0.05). Studies in isolated mtAQP8-knockdown mitochondria showed that H{sub 2}O{sub 2} release, assessed by Amplex Red, was reduced by about 45% (p < 0.05), an effect not observed in digitonin-permeabilized mitochondria. mtAQP8-knockdown cells showed an increase in mitochondrial ROS, assessed by dichlorodihydrofluorescein diacetate (+ 120%, p < 0.05) and loss of mitochondrial membrane potential (− 80%, p < 0.05), assessed by tetramethylrhodamine-coupled quantitative fluorescence microscopy. The mitochondria-targeted antioxidant MitoTempol prevented ROS accumulation and dissipation of mitochondrial membrane potential. Cyclosporin A, a mitochondrial permeability transition pore blocker, also abolished the mtAQP8 knockdown-induced mitochondrial depolarization. Besides, the loss of viability in mtAQP8 knockdown cells verified by MTT assay, LDH leakage, and trypan blue exclusion test could be prevented by cyclosporin A. Our data on human hepatoma HepG2 cells suggest that mtAQP8 facilitates mitochondrial H{sub 2}O{sub 2} release and that its defective expression causes ROS-induced mitochondrial depolarization via the mitochondrial permeability transition mechanism, and cell death. -- Highlights: ► Aquaporin-8 is expressed in mitochondria of human hepatoma HepG2 cells. ► Aquaporin-8 knockdown impairs mitochondrial H{sub 2}O{sub 2} release and increases ROS. ► Aquaporin

  2. Human Misato regulates mitochondrial distribution and morphology

    SciTech Connect

    Kimura, Masashi . E-mail: yo@gifu-u.ac.jp; Okano, Yukio

    2007-04-15

    Misato of Drosophila melanogaster and Saccharomyces cerevisiae DML1 are conserved proteins having a homologous region with a part of the GTPase family that includes eukaryotic tubulin and prokaryotic FtsZ. We characterized human Misato sharing homology with Misato of D. melanogaster and S. cerevisiae DML1. Tissue distribution of Misato exhibited ubiquitous distribution. Subcellular localization of the protein studied using anti-Misato antibody suggested that it is localized to the mitochondria. Further experiments of fractionating mitochondria revealed that Misato was localized to the outer membrane. The transfection of Misato siRNA led to growth deficiencies compared with control siRNA transfected HeLa cells, and the Misato-depleted HeLa cells showed apoptotic nuclear fragmentation resulting in cell death. After silencing of Misato, the filamentous mitochondrial network disappeared and fragmented mitochondria were observed, indicating human Misato has a role in mitochondrial fusion. To examine the effects of overexpression, COS-7 cells were transfected with cDNA encoding EGFP-Misato. Its overexpression resulted in the formation of perinuclear aggregations of mitochondria in these cells. The Misato-overexpressing cells showed low viability and had no nuclei or a small and structurally unusual ones. These results indicated that human Misato has a role(s) in mitochondrial distribution and morphology and that its unregulated expression leads to cell death.

  3. Mitochondrial Redox Dysfunction and Environmental Exposures

    PubMed Central

    Caito, Samuel W.

    2015-01-01

    Abstract Significance: Mitochondria are structurally and biochemically diverse, even within a single type of cell. Protein complexes localized to the inner mitochondrial membrane synthesize ATP by coupling electron transport and oxidative phosphorylation. The organelles produce reactive oxygen species (ROS) from mitochondrial oxygen and ROS can, in turn, alter the function and expression of proteins used for aerobic respiration by post-translational and transcriptional regulation. Recent Advances: New interest is emerging not only into the roles of mitochondria in disease development and progression but also as a target for environmental toxicants. Critical Issues: Dysregulation of respiration has been linked to cell death and is a major contributor to acute neuronal trauma, peripheral diseases, as well as chronic neurodegenerative diseases, such as Parkinson's disease and Alzheimer's disease. Future Directions: Here, we discuss the mechanisms underlying the sensitivity of the mitochondrial respiratory complexes to redox modulation, as well as examine the effects of environmental contaminants that have well-characterized mitochondrial toxicity. The contaminants discussed in this review are some of the most prevalent and potent environmental contaminants that have been linked to neurological dysfunction, altered cellular respiration, and oxidation. Antioxid. Redox Signal. 23, 578–595. PMID:25826672

  4. Death of mitochondria during programmed cell death of leaf mesophyll cells.

    PubMed

    Selga, Tūrs; Selga, Maija; Pāvila, Vineta

    2005-12-01

    The role of plant mitochondria in the programmed cell death (PCD) is widely discussed. However, spectrum and sequence of mitochondrial structural changes during different types of PCD in leaves are poorly described. Pea, cucumber and rye plants were grown under controlled growing conditions. A part of them were sprinkled with ethylene releaser to accelerate cell death. During yellowing the palisade parenchyma mitochondria were attracted to nuclear envelope. Mitochondrial matrix became electron translucent. Mitochondria entered vacuole by invagination of tonoplast and formed multivesicular bodies. Ethephon treatment increased the frequency of sticking of mitochondria to the nuclear envelope or chloroplasts and peroxisomes. Mitochondria divided by different mechanisms and became enclosed in Golgi and ER derived authopagic vacuoles or in the central vacuole. Several fold increase of the diameter of cristae became typical. In all cases mitochondria were attached to nuclear envelope. It can be considered as structural mechanism of promoting of PCD.

  5. Mitochondrial aquaporin-8 knockdown in human hepatoma HepG2 cells causes ROS-induced mitochondrial depolarization and loss of viability.

    PubMed

    Marchissio, Maria Julia; Francés, Daniel Eleazar Antonio; Carnovale, Cristina Ester; Marinelli, Raúl Alberto

    2012-10-15

    Human aquaporin-8 (AQP8) channels facilitate the diffusional transport of H(2)O(2) across membranes. Since AQP8 is expressed in hepatic inner mitochondrial membranes, we studied whether mitochondrial AQP8 (mtAQP8) knockdown in human hepatoma HepG2 cells impairs mitochondrial H(2)O(2) release, which may lead to organelle dysfunction and cell death. We confirmed AQP8 expression in HepG2 inner mitochondrial membranes and found that 72h after cell transfection with siRNAs targeting two different regions of the human AQP8 molecule, mtAQP8 protein specifically decreased by around 60% (p<0.05). Studies in isolated mtAQP8-knockdown mitochondria showed that H(2)O(2) release, assessed by Amplex Red, was reduced by about 45% (p<0.05), an effect not observed in digitonin-permeabilized mitochondria. mtAQP8-knockdown cells showed an increase in mitochondrial ROS, assessed by dichlorodihydrofluorescein diacetate (+120%, p<0.05) and loss of mitochondrial membrane potential (-80%, p<0.05), assessed by tetramethylrhodamine-coupled quantitative fluorescence microscopy. The mitochondria-targeted antioxidant MitoTempol prevented ROS accumulation and dissipation of mitochondrial membrane potential. Cyclosporin A, a mitochondrial permeability transition pore blocker, also abolished the mtAQP8 knockdown-induced mitochondrial depolarization. Besides, the loss of viability in mtAQP8 knockdown cells verified by MTT assay, LDH leakage, and trypan blue exclusion test could be prevented by cyclosporin A. Our data on human hepatoma HepG2 cells suggest that mtAQP8 facilitates mitochondrial H(2)O(2) release and that its defective expression causes ROS-induced mitochondrial depolarization via the mitochondrial permeability transition mechanism, and cell death. PMID:22910329

  6. Programmed cell death and hybrid incompatibility.

    PubMed

    Frank, S A; Barr, C M

    2003-01-01

    We propose a new theory to explain developmental aberrations in plant hybrids. In our theory, hybrid incompatibilities arise from imbalances in the mechanisms that cause male sterility in hermaphroditic plants. Mitochondria often cause male sterility by killing the tapetal tissue that nurtures pollen mother cells. Recent evidence suggests that mitochondria destroy the tapetum by triggering standard pathways of programmed cell death. Some nuclear genotypes repress mitochondrial male sterility and restore pollen fertility. Normal regulation of tapetal development therefore arises from a delicate balance between the disruptive effects of mitochondria and the defensive countermeasures of the nuclear genes. In hybrids, incompatibilities between male-sterile mitochondria and nuclear restorers may frequently upset the regulatory control of programmed cell death, causing tapetal abnormalities and male sterility. We propose that hybrid misregulation of programmed cell death may also spill over into other tissues, explaining various developmental aberrations observed in hybrids.

  7. SR/ER-mitochondrial local communication: Calcium and ROS

    PubMed Central

    Csordás, György; Hajnóczky, György

    2009-01-01

    Mitochondria form junctions with the sarco/endoplasmic reticulum (SR/ER), which support signal transduction and biosynthetic pathways and affect organellar distribution. Recently, these junctions have received attention because of their pivotal role in mediating calcium signal propagation to the mitochondria, which is important for both ATP production and mitochondrial cell death. Many of the SR/ER-mitochondrial calcium transporters and signaling proteins are sensitive to redox regulation and are directly exposed to the reactive oxygen species (ROS) produced in the mitochondria and SR/ER. Although ROS has been emerging as a novel signaling entity, the redox signaling of the SR/ER-mitochondrial interface is yet to be elucidated. We describe here possible mechanisms of the mutual interaction between local Ca2+ and ROS signaling in the control of SR/ER-mitochondrial function. PMID:19527680

  8. Impaired ALDH2 activity decreases the mitochondrial respiration in H9C2 cardiomyocytes.

    PubMed

    Mali, Vishal R; Deshpande, Mandar; Pan, Guodong; Thandavarayan, Rajarajan A; Palaniyandi, Suresh S

    2016-02-01

    Reactive oxygen species (ROS)-mediated reactive aldehydes induce cellular stress. In cardiovascular diseases such as ischemia-reperfusion injury, lipid-peroxidation derived reactive aldehydes such as 4-hydroxy-2-nonenal (4HNE) are known to contribute to the pathogenesis. 4HNE is involved in ROS formation, abnormal calcium handling and more importantly defective mitochondrial respiration. Aldehyde dehydrogenase (ALDH) superfamily contains NAD(P)(+)-dependent isozymes which can detoxify endogenous and exogenous aldehydes into non-toxic carboxylic acids. Therefore we hypothesize that 4HNE afflicts mitochondrial respiration and leads to cell death by impairing ALDH2 activity in cultured H9C2 cardiomyocyte cell lines. H9C2 cardiomyocytes were treated with 25, 50 and 75 μM 4HNE and its vehicle, ethanol as well as 25, 50 and 75 μM disulfiram (DSF), an inhibitor of ALDH2 and its vehicle (DMSO) for 4 h. 4HNE significantly decreased ALDH2 activity, ALDH2 protein levels, mitochondrial respiration and mitochondrial respiratory reserve capacity, and increased 4HNE adduct formation and cell death in cultured H9C2 cardiomyocytes. ALDH2 inhibition by DSF and ALDH2 siRNA attenuated ALDH2 activity besides reducing ALDH2 levels, mitochondrial respiration and mitochondrial respiratory reserve capacity and increased cell death. Our results indicate that ALDH2 impairment can lead to poor mitochondrial respiration and increased cell death in cultured H9C2 cardiomyocytes.

  9. Translocator Protein-Mediated Stabilization of Mitochondrial Architecture during Inflammation Stress in Colonic Cells

    PubMed Central

    Issop, Leeyah; Ostuni, Mariano A.; Lee, Sunghoon; Laforge, Mireille; Péranzi, Gabriel; Rustin, Pierre; Benoist, Jean-François; Estaquier, Jérome; Papadopoulos, Vassilios; Lacapère, Jean-Jacques

    2016-01-01

    Chronic inflammation of the gastrointestinal tract increasing the risk of cancer has been described to be linked to the high expression of the mitochondrial translocator protein (18 kDa; TSPO). Accordingly, TSPO drug ligands have been shown to regulate cytokine production and to improve tissue reconstruction. We used HT-29 human colon carcinoma cells to evaluate the role of TSPO and its drug ligands in tumor necrosis factor (TNF)-induced inflammation. TNF-induced interleukin (IL)-8 expression, coupled to reactive oxygen species (ROS) production, was followed by TSPO overexpression. TNF also destabilized mitochondrial ultrastructure, inducing cell death by apoptosis. Treatment with the TSPO drug ligand PK 11195 maintained the mitochondrial ultrastructure, reducing IL-8 and ROS production and cell death. TSPO silencing and overexpression studies demonstrated that the presence of TSPO is essential to control IL-8 and ROS production, so as to maintain mitochondrial ultrastructure and to prevent cell death. Taken together, our data indicate that inflammation results in the disruption of mitochondrial complexes containing TSPO, leading to cell death and epithelia disruption. Significance: This work implicates TSPO in the maintenance of mitochondrial membrane integrity and in the control of mitochondrial ROS production, ultimately favoring tissue regeneration. PMID:27054921

  10. Viral Control of Mitochondrial Apoptosis

    PubMed Central

    Morselli, Eugenia; Touat, Zahia; Kroemer, Guido

    2008-01-01

    Throughout the process of pathogen–host co-evolution, viruses have developed a battery of distinct strategies to overcome biochemical and immunological defenses of the host. Thus, viruses have acquired the capacity to subvert host cell apoptosis, control inflammatory responses, and evade immune reactions. Since the elimination of infected cells via programmed cell death is one of the most ancestral defense mechanisms against infection, disabling host cell apoptosis might represent an almost obligate step in the viral life cycle. Conversely, viruses may take advantage of stimulating apoptosis, either to kill uninfected cells from the immune system, or to induce the breakdown of infected cells, thereby favoring viral dissemination. Several viral polypeptides are homologs of host-derived apoptosis-regulatory proteins, such as members of the Bcl-2 family. Moreover, viral factors with no homology to host proteins specifically target key components of the apoptotic machinery. Here, we summarize the current knowledge on the viral modulation of mitochondrial apoptosis, by focusing in particular on the mechanisms by which viral proteins control the host cell death apparatus. PMID:18516228

  11. Children and Death.

    ERIC Educational Resources Information Center

    Brennan, Andrew J. J.

    Health professionals and educators should develop their abilities to educate about death and to comfort the bereaved. Due to lower death rates, the lack of philosophical religious views, and distorted perceptions of death contributed by television, death has become a mystery instead of a segment of the common experience. Particularly when a child…

  12. Inhibition of the Mitochondrial Permeability Transition for Cytoprotection: Direct versus Indirect Mechanisms

    PubMed Central

    Martel, Cécile; Huynh, Le Ha; Garnier, Anne; Ventura-Clapier, Renée; Brenner, Catherine

    2012-01-01

    Mitochondria are fascinating organelles, which fulfill multiple cellular functions, as diverse as energy production, fatty acid β oxidation, reactive oxygen species (ROS) production and detoxification, and cell death regulation. The coordination of these functions relies on autonomous mitochondrial processes as well as on sustained cross-talk with other organelles and/or the cytosol. Therefore, this implies a tight regulation of mitochondrial functions to ensure cell homeostasis. In many diseases (e.g., cancer, cardiopathies, nonalcoholic fatty liver diseases, and neurodegenerative diseases), mitochondria can receive harmful signals, dysfunction and then, participate to pathogenesis. They can undergo either a decrease of their bioenergetic function or a process called mitochondrial permeability transition (MPT) that can coordinate cell death execution. Many studies present evidence that protection of mitochondria limits disease progression and severity. Here, we will review recent strategies to preserve mitochondrial functions via direct or indirect mechanisms of MPT inhibition. Thus, several mitochondrial proteins may be considered for cytoprotective-targeted therapies. PMID:22675634

  13. What do we not know about mitochondrial potassium channels?

    PubMed

    Laskowski, Michał; Augustynek, Bartłomiej; Kulawiak, Bogusz; Koprowski, Piotr; Bednarczyk, Piotr; Jarmuszkiewicz, Wieslawa; Szewczyk, Adam

    2016-08-01

    In this review, we summarize our knowledge about mitochondrial potassium channels, with a special focus on unanswered questions in this field. The following potassium channels have been well described in the inner mitochondrial membrane: ATP-regulated potassium channel, Ca(2+)-activated potassium channel, the voltage-gated Kv1.3 potassium channel, and the two-pore domain TASK-3 potassium channel. The primary functional roles of these channels include regulation of mitochondrial respiration and the alteration of membrane potential. Additionally, they modulate the mitochondrial matrix volume and the synthesis of reactive oxygen species by mitochondria. Mitochondrial potassium channels are believed to contribute to cytoprotection and cell death. In this paper, we discuss fundamental issues concerning mitochondrial potassium channels: their molecular identity, channel pharmacology and functional properties. Attention will be given to the current problems present in our understanding of the nature of mitochondrial potassium channels. This article is part of a Special Issue entitled 'EBEC 2016: 19th European Bioenergetics Conference, Riva del Garda, Italy, July 2-6, 2016', edited by Prof. Paolo Bernardi.

  14. Measurement of mitochondrial NADH and FAD autofluorescence in live cells.

    PubMed

    Bartolomé, Fernando; Abramov, Andrey Y

    2015-01-01

    In the process of energy production, mitochondrial networks are key elements to allow metabolism of substrates into ATP. Many pathological conditions have been associated with mitochondrial dysfunction as mitochondria are associated with a wide range of cellular processes. Therefore, any disruption in the energy production induces devastating effects that can ultimately lead to cell death due to chemical ischemia. To address the mitochondrial health and function, there are several bioenergetic parameters reflecting either whole mitochondrial functionality or individual mitochondrial complexes. Particularly, metabolism of nutrients in the tricarboxylic acid cycle provides substrates used to generate electron carriers (nicotinamide adenine dinucleotide [NADH] and flavin adenine dinucleotide [FADH2]) which ultimately donate electrons to the mitochondrial electron transport chain. The levels of NADH and FADH2 can be estimated through imaging of NADH/NAD(P)H or FAD autofluorescence. This report demonstrates how to perform and analyze NADH/NAD(P)H and FAD autofluorescence in a time-course-dependent manner and provides information about NADH and FAD redox indexes both reflecting the activity of the mitochondrial electron transport chain (ETC). Furthermore, total pools of NADH and FAD can be estimated providing information about the rate of substrate supply into the ETC. Finally, the analysis of NADH autofluorescence after induction of maximal respiration can offer information about the pentose phosphate pathway activity where glucose can be alternatively oxidized instead of pyruvate. PMID:25631020

  15. Endoplasmic reticulum: ER stress regulates mitochondrial bioenergetics.

    PubMed

    Bravo, Roberto; Gutierrez, Tomás; Paredes, Felipe; Gatica, Damián; Rodriguez, Andrea E; Pedrozo, Zully; Chiong, Mario; Parra, Valentina; Quest, Andrew F G; Rothermel, Beverly A; Lavandero, Sergio

    2012-01-01

    Endoplasmic reticulum (ER) stress activates an adaptive unfolded protein response (UPR) that facilitates cellular repair, however, under prolonged ER stress, the UPR can ultimately trigger apoptosis thereby terminating damaged cells. The molecular mechanisms responsible for execution of the cell death program are relatively well characterized, but the metabolic events taking place during the adaptive phase of ER stress remain largely undefined. Here we discuss emerging evidence regarding the metabolic changes that occur during the onset of ER stress and how ER influences mitochondrial function through mechanisms involving calcium transfer, thereby facilitating cellular adaptation. Finally, we highlight how dysregulation of ER-mitochondrial calcium homeostasis during prolonged ER stress is emerging as a novel mechanism implicated in the onset of metabolic disorders. PMID:22064245

  16. Mitochondrial biogenesis: pharmacological approaches.

    PubMed

    Valero, Teresa

    2014-01-01

    Organelle biogenesis is concomitant to organelle inheritance during cell division. It is necessary that organelles double their size and divide to give rise to two identical daughter cells. Mitochondrial biogenesis occurs by growth and division of pre-existing organelles and is temporally coordinated with cell cycle events [1]. However, mitochondrial biogenesis is not only produced in association with cell division. It can be produced in response to an oxidative stimulus, to an increase in the energy requirements of the cells, to exercise training, to electrical stimulation, to hormones, during development, in certain mitochondrial diseases, etc. [2]. Mitochondrial biogenesis is therefore defined as the process via which cells increase their individual mitochondrial mass [3]. Recent discoveries have raised attention to mitochondrial biogenesis as a potential target to treat diseases which up to date do not have an efficient cure. Mitochondria, as the major ROS producer and the major antioxidant producer exert a crucial role within the cell mediating processes such as apoptosis, detoxification, Ca2+ buffering, etc. This pivotal role makes mitochondria a potential target to treat a great variety of diseases. Mitochondrial biogenesis can be pharmacologically manipulated. This issue tries to cover a number of approaches to treat several diseases through triggering mitochondrial biogenesis. It contains recent discoveries in this novel field, focusing on advanced mitochondrial therapies to chronic and degenerative diseases, mitochondrial diseases, lifespan extension, mitohormesis, intracellular signaling, new pharmacological targets and natural therapies. It contributes to the field by covering and gathering the scarcely reported pharmacological approaches in the novel and promising field of mitochondrial biogenesis. There are several diseases that have a mitochondrial origin such as chronic progressive external ophthalmoplegia (CPEO) and the Kearns- Sayre syndrome (KSS

  17. Mitochondrial biogenesis: pharmacological approaches.

    PubMed

    Valero, Teresa

    2014-01-01

    Organelle biogenesis is concomitant to organelle inheritance during cell division. It is necessary that organelles double their size and divide to give rise to two identical daughter cells. Mitochondrial biogenesis occurs by growth and division of pre-existing organelles and is temporally coordinated with cell cycle events [1]. However, mitochondrial biogenesis is not only produced in association with cell division. It can be produced in response to an oxidative stimulus, to an increase in the energy requirements of the cells, to exercise training, to electrical stimulation, to hormones, during development, in certain mitochondrial diseases, etc. [2]. Mitochondrial biogenesis is therefore defined as the process via which cells increase their individual mitochondrial mass [3]. Recent discoveries have raised attention to mitochondrial biogenesis as a potential target to treat diseases which up to date do not have an efficient cure. Mitochondria, as the major ROS producer and the major antioxidant producer exert a crucial role within the cell mediating processes such as apoptosis, detoxification, Ca2+ buffering, etc. This pivotal role makes mitochondria a potential target to treat a great variety of diseases. Mitochondrial biogenesis can be pharmacologically manipulated. This issue tries to cover a number of approaches to treat several diseases through triggering mitochondrial biogenesis. It contains recent discoveries in this novel field, focusing on advanced mitochondrial therapies to chronic and degenerative diseases, mitochondrial diseases, lifespan extension, mitohormesis, intracellular signaling, new pharmacological targets and natural therapies. It contributes to the field by covering and gathering the scarcely reported pharmacological approaches in the novel and promising field of mitochondrial biogenesis. There are several diseases that have a mitochondrial origin such as chronic progressive external ophthalmoplegia (CPEO) and the Kearns- Sayre syndrome (KSS

  18. [Brain death: biological and ethical aspects].

    PubMed

    Roczeń, R; Bohatyrewicz, R

    2001-01-01

    The article presents briefly historical development of death criteria from the modern times to the present. The criteria which are used for identification and diagnosing death on the base of respiratory and circulatory death definition are described. This work underlines the inadequacy of the definition of the brain death in relation to patients with persistent vegetative state and in relation to anencephalic newborns. The author describes the pathology and clinical and laboratory evidence of the brain stem death, which gave the possibility to justify the thesis that in case of the brain stem death ontological arguments are sufficient for diagnosing the death of a human being. The attention of the ethic of the life sanctity (on the base of halachic's law) and its opposing influence on the evolution of the medical definition of death has been paid. The recognition of the brain as the death of an individual is a cultural shock, which from scientific point of view changed the ways of thinking, almost immediately but did not in the awareness of the society. The work also underlies the fact that utilitarian argumentation can not be a criterion for making a decision concerning the life of an individual.

  19. Mitochondrial calcium uniporter Mcu controls excitotoxicity and is transcriptionally repressed by neuroprotective nuclear calcium signals

    PubMed Central

    Qiu, Jing; Tan, Yan-Wei; Hagenston, Anna M.; Martel, Marc-Andre; Kneisel, Niclas; Skehel, Paul A.; Wyllie, David J. A.; Bading, Hilmar; Hardingham, Giles E.

    2013-01-01

    The recent identification of the mitochondrial Ca2+ uniporter gene (Mcu/Ccdc109a) has enabled us to address its role, and that of mitochondrial Ca2+ uptake, in neuronal excitotoxicity. Here we show that exogenously expressed Mcu is mitochondrially localized and increases mitochondrial Ca2+ levels following NMDA receptor activation, leading to increased mitochondrial membrane depolarization and excitotoxic cell death. Knockdown of endogenous Mcu expression reduces NMDA-induced increases in mitochondrial Ca2+, resulting in lower levels of mitochondrial depolarization and resistance to excitotoxicity. Mcu is subject to dynamic regulation as part of an activity-dependent adaptive mechanism that limits mitochondrial Ca2+ overload when cytoplasmic Ca2+ levels are high. Specifically, synaptic activity transcriptionally represses Mcu, via a mechanism involving the nuclear Ca2+ and CaM kinase-mediated induction of Npas4, resulting in the inhibition of NMDA receptor-induced mitochondrial Ca2+ uptake and preventing excitotoxic death. This establishes Mcu and the pathways regulating its expression as important determinants of excitotoxicity, which may represent therapeutic targets for excitotoxic disorders. PMID:23774321

  20. Mitochondrial calcium uniporter Mcu controls excitotoxicity and is transcriptionally repressed by neuroprotective nuclear calcium signals.

    PubMed

    Qiu, Jing; Tan, Yan-Wei; Hagenston, Anna M; Martel, Marc-Andre; Kneisel, Niclas; Skehel, Paul A; Wyllie, David J A; Bading, Hilmar; Hardingham, Giles E

    2013-01-01

    The recent identification of the mitochondrial Ca(2+) uniporter gene (Mcu/Ccdc109a) has enabled us to address its role, and that of mitochondrial Ca(2+) uptake, in neuronal excitotoxicity. Here we show that exogenously expressed Mcu is mitochondrially localized and increases mitochondrial Ca(2+) levels following NMDA receptor activation, leading to increased mitochondrial membrane depolarization and excitotoxic cell death. Knockdown of endogenous Mcu expression reduces NMDA-induced increases in mitochondrial Ca(2+), resulting in lower levels of mitochondrial depolarization and resistance to excitotoxicity. Mcu is subject to dynamic regulation as part of an activity-dependent adaptive mechanism that limits mitochondrial Ca(2+) overload when cytoplasmic Ca(2+) levels are high. Specifically, synaptic activity transcriptionally represses Mcu, via a mechanism involving the nuclear Ca(2+) and CaM kinase-mediated induction of Npas4, resulting in the inhibition of NMDA receptor-induced mitochondrial Ca(2+) uptake and preventing excitotoxic death. This establishes Mcu and the pathways regulating its expression as important determinants of excitotoxicity, which may represent therapeutic targets for excitotoxic disorders.

  1. United Mitochondrial Disease Foundation

    MedlinePlus

    ... to Mitochondrial Disease FAQ's MitoFirst Handbook More Information Mito 101 Symposium Archives Get Connected Find an Event Adult Advisory Council Team Ask The Mito Doc Grand Rounds Kids & Teens Medical Child Abuse ...

  2. MITOCHONDRIA-DERIVED REACTIVE OXYGEN SPECIES MEDIATE CASPASE- DEPENDENT AND-INDEPENDENT NEURONAL DEATH

    PubMed Central

    McManus, Meagan J.; Murphy, Michael P.

    2014-01-01

    Mitochondrial dysfunction and oxidative stress are implicated in many neurodegenerative diseases. Mitochondria-targeted drugs that effectively decrease oxidative stress, protect mitochondrial energetics, and prevent neuronal loss may therefore lend therapeutic benefit to these currently incurable diseases. To investigate the efficacy of such drugs, we examined the effects of mitochondria-targeted antioxidants MitoQ10 and MitoE2 on neuronal death induced by neurotrophin deficiency. Our results indicate that MitoQ10 blocked apoptosis by preventing increased mitochondria-derived reactive oxygen species (ROS) and subsequent cytochrome c release, caspase activation, and mitochondrial damage in nerve growth factor (NGF)-deprived sympathetic neurons, while MitoE2 was largely ineffective. In this paradigm, the most proximal point of divergence was the ability of MitoQ10 to scavenge mitochondrial superoxide (O2•−). MitoQ10 also prevented caspase-independent neuronal death in these cells demonstrating that the mitochondrial redox state significantly influences both apoptotic and nonapoptotic pathways leading to neuronal death. We suggest that mitochondria-targeted antioxidants may provide tools for delineating the role and significance of mitochondrial ROS in neuronal death and provide a new therapeutic approach for neurodegenerative conditions involving trophic factor deficits and multiple modes of cell death. PMID:25239010

  3. DJ-1 binds to mitochondrial complex I and maintains its activity

    SciTech Connect

    Hayashi, Takuya; Ishimori, Chikako; Takahashi-Niki, Kazuko; Taira, Takahiro; Kim, Yun-chul; Maita, Hiroshi; Maita, Chinatsu; Ariga, Hiroyoshi; Iguchi-Ariga, Sanae M.M.

    2009-12-18

    Parkinson's disease (PD) is caused by neuronal cell death, and oxidative stress and mitochondrial dysfunction are thought to be responsible for onset of PD. DJ-1, a causative gene product of a familial form of Parkinson's disease, PARK7, plays roles in transcriptional regulation and anti-oxidative stress. The possible mitochondrial function of DJ-1 has been proposed, but its exact function remains unclear. In this study, we found that DJ-1 directly bound to NDUFA4 and ND1, nuclear and mitochondrial DNA-encoding subunits of mitochondrial complex I, respectively, and was colocalized with complex I and that complex I activity was reduced in DJ-1-knockdown NIH3T3 and HEK293 cells. These findings suggest that DJ-1 is an integral mitochondrial protein and that DJ-1 plays a role in maintenance of mitochondrial complex I activity.

  4. SUMO-regulated mitochondrial function in Parkinson's disease.

    PubMed

    Guerra de Souza, Ana Cristina; Prediger, Rui Daniel; Cimarosti, Helena

    2016-06-01

    Parkinson's disease (PD) is the second most common neurodegenerative disorder characterized by cardinal motor signs such as rigidity, bradykinesia or rest tremor that arise from a significant death of dopaminergic neurons. Non-dopaminergic degeneration also occurs and it seems to induce the deficits in olfactory, emotional, and memory functions that precede the classical motor symptoms in PD. Despite the majority of PD cases being sporadic, several genes have previously been associated with the hereditary forms of the disease. The proteins encoded by some of these genes, including α-synuclein, DJ-1, and parkin, are modified by small ubiquitin-like modifier (SUMO), a post-translational modification that regulates a variety of cellular processes. Among the several pathogenic mechanisms proposed for PD is mitochondrial dysfunction. Recent studies suggest that SUMOylation can interfere with mitochondrial dynamics, which is essential for neuronal function, and may play a pivotal role in PD pathogenesis. Here, we present an overview of recent studies on mitochondrial disturbance in PD and the potential SUMO-modified proteins and pathways involved in this process. SUMOylation, a post-translational modification, interferes with mitochondrial dynamics, and may play a pivotal role in Parkinson's disease (PD). SUMOylation maintains α-synuclein (α-syn) in a soluble form and activates DJ-1, decreasing mitochondrial oxidative stress. SUMOylation may reduce the amount of parkin available for mitochondrial recruitment and decreases mitochondrial biogenesis through suppression of peroxisomal proliferator-activated receptor-γ co-activator 1 α (PGC-1α). Mitochondrial fission can be regulated by dynamin-related protein 1 SUMO-1- or SUMO-2/3-ylation. A fine balance for the SUMOylation/deSUMOylation of these proteins is required to ensure adequate mitochondrial function in PD. PMID:26932327

  5. The proline metabolism intermediate Δ1-pyrroline-5-carboxylate directly inhibits the mitochondrial respiration in budding yeast.

    PubMed

    Nishimura, Akira; Nasuno, Ryo; Takagi, Hiroshi

    2012-07-30

    The proline metabolism intermediate Δ(1)-pyrroline-5-carboxylate (P5C) induces cell death in animals, plants and yeasts. To elucidate how P5C triggers cell death, we analyzed P5C metabolism, mitochondrial respiration and superoxide anion generation in the yeast Saccharomyces cerevisiae. Gene disruption analysis revealed that P5C-mediated cell death was not due to P5C metabolism. Interestingly, deficiency in mitochondrial respiration suppressed the sensitivity of yeast cells to P5C. In addition, we found that P5C inhibits the mitochondrial respiration and induces a burst of superoxide anions from the mitochondria. We propose that P5C regulates cell death via the inhibition of mitochondrial respiration.

  6. Melatonin prevents the dynamin-related protein 1-dependent mitochondrial fission and oxidative insult in the cortical neurons after 1-methyl-4-phenylpyridinium treatment.

    PubMed

    Chuang, Jih-Ing; Pan, I-Ling; Hsieh, Chia-Yun; Huang, Chiu-Ying; Chen, Pei-Chun; Shin, Jyh Wei

    2016-09-01

    Mitochondrial dysfunction and oxidative stress are involved in the pathogenesis of Parkinson's disease (PD). Mitochondrial morphology is dynamic and precisely regulated by the mitochondrial fission and fusion machinery. Aberrant mitochondrial fragmentation controlled by the mitochondrial fission protein, dynamin-related protein 1 (Drp1), may result in cell death. Our previous results showed that melatonin protected neurons by inhibiting oxidative stress in a 1-methyl-4-phenylpyridinium (MPP(+) )-induced PD model. However, the effect of melatonin on mitochondrial dynamics remains uncharacterized. Herein, we investigated the effect of melatonin and the role of Drp1 on MPP(+) -induced mitochondrial fission in rat primary cortical neurons. We found that MPP(+) induced a rapid increase in the ratio of GSSG:total glutathione (a marker of oxidative stress) and mitochondrial fragmentation, Drp1 upregulation within 4 hours, and finally resulted in neuron loss 48 hours after the treatment. Neurons overexpressing wild-type Drp1 promoted mitochondrial and nuclear fragmentation; however, neurons overexpressing dominant-negative Drp1(K38A) or cotreated with melatonin exhibited significantly reduced MPP(+) -induced mitochondrial fragmentation and neuron death. Moreover, melatonin cotreatment prevented an MPP(+) -induced high ratio of GSSG and mitochondrial Drp1 upregulation. The prevention of mitochondrial fission by melatonin was not found in neurons transfected with wild-type Drp1. These results provide a new insight that the neuroprotective effect of melatonin against MPP(+) toxicity is mediated by inhibiting the oxidative stress and Drp1-mediated mitochondrial fragmentation.

  7. Dengue Virus Impairs Mitochondrial Fusion by Cleaving Mitofusins.

    PubMed

    Yu, Chia-Yi; Liang, Jian-Jong; Li, Jin-Kun; Lee, Yi-Ling; Chang, Bi-Lan; Su, Chan-I; Huang, Wei-Jheng; Lai, Michael M C; Lin, Yi-Ling

    2015-12-01

    Mitochondria are highly dynamic subcellular organelles participating in many signaling pathways such as antiviral innate immunity and cell death cascades. Here we found that mitochondrial fusion was impaired in dengue virus (DENV) infected cells. Two mitofusins (MFN1 and MFN2), which mediate mitochondrial fusion and participate in the proper function of mitochondria, were cleaved by DENV protease NS2B3. By knockdown and overexpression approaches, these two MFNs showed diverse functions in DENV infection. MFN1 was required for efficient antiviral retinoic acid-inducible gene I-like receptor signaling to suppress DENV replication, while MFN2 participated in maintaining mitochondrial membrane potential (MMP) to attenuate DENV-induced cell death. Cleaving MFN1 and MFN2 by DENV protease suppressed mitochondrial fusion and deteriorated DENV-induced cytopathic effects through subverting interferon production and facilitating MMP disruption. Thus, MFNs participate in host defense against DENV infection by promoting the antiviral response and cell survival, and DENV regulates mitochondrial morphology by cleaving MFNs to manipulate the outcome of infection. PMID:26717518

  8. Bee Venom Protects against Rotenone-Induced Cell Death in NSC34 Motor Neuron Cells.

    PubMed

    Jung, So Young; Lee, Kang-Woo; Choi, Sun-Mi; Yang, Eun Jin

    2015-09-01

    Rotenone, an inhibitor of mitochondrial complex I of the mitochondrial respiratory chain, is known to elevate mitochondrial reactive oxygen species and induce apoptosis via activation of the caspase-3 pathway. Bee venom (BV) extracted from honey bees has been widely used in oriental medicine and contains melittin, apamin, adolapin, mast cell-degranulating peptide, and phospholipase A₂. In this study, we tested the effects of BV on neuronal cell death by examining rotenone-induced mitochondrial dysfunction. NSC34 motor neuron cells were pretreated with 2.5 μg/mL BV and stimulated with 10 μM rotenone to induce cell toxicity. We assessed cell death by Western blotting using specific antibodies, such as phospho-ERK1/2, phospho-JNK, and cleaved capase-3 and performed an MTT assay for evaluation of cell death and mitochondria staining. Pretreatment with 2.5 μg/mL BV had a neuroprotective effect against 10 μM rotenone-induced cell death in NSC34 motor neuron cells. Pre-treatment with BV significantly enhanced cell viability and ameliorated mitochondrial impairment in rotenone-treated cellular model. Moreover, BV treatment inhibited the activation of JNK signaling and cleaved caspase-3 related to cell death and increased ERK phosphorylation involved in cell survival in rotenone-treated NSC34 motor neuron cells. Taken together, we suggest that BV treatment can be useful for protection of neurons against oxidative stress or neurotoxin-induced cell death. PMID:26402700

  9. Bee Venom Protects against Rotenone-Induced Cell Death in NSC34 Motor Neuron Cells

    PubMed Central

    Jung, So Young; Lee, Kang-Woo; Choi, Sun-Mi; Yang, Eun Jin

    2015-01-01

    Rotenone, an inhibitor of mitochondrial complex I of the mitochondrial respiratory chain, is known to elevate mitochondrial reactive oxygen species and induce apoptosis via activation of the caspase-3 pathway. Bee venom (BV) extracted from honey bees has been widely used in oriental medicine and contains melittin, apamin, adolapin, mast cell-degranulating peptide, and phospholipase A2. In this study, we tested the effects of BV on neuronal cell death by examining rotenone-induced mitochondrial dysfunction. NSC34 motor neuron cells were pretreated with 2.5 μg/mL BV and stimulated with 10 μM rotenone to induce cell toxicity. We assessed cell death by Western blotting using specific antibodies, such as phospho-ERK1/2, phospho-JNK, and cleaved capase-3 and performed an MTT assay for evaluation of cell death and mitochondria staining. Pretreatment with 2.5 μg/mL BV had a neuroprotective effect against 10 μM rotenone-induced cell death in NSC34 motor neuron cells. Pre-treatment with BV significantly enhanced cell viability and ameliorated mitochondrial impairment in rotenone-treated cellular model. Moreover, BV treatment inhibited the activation of JNK signaling and cleaved caspase-3 related to cell death and increased ERK phosphorylation involved in cell survival in rotenone-treated NSC34 motor neuron cells. Taken together, we suggest that BV treatment can be useful for protection of neurons against oxidative stress or neurotoxin-induced cell death. PMID:26402700

  10. Sodium valproate induces mitochondrial respiration dysfunction in HepG2 in vitro cell model.

    PubMed

    Komulainen, Tuomas; Lodge, Tiffany; Hinttala, Reetta; Bolszak, Maija; Pietilä, Mika; Koivunen, Peppi; Hakkola, Jukka; Poulton, Joanna; Morten, Karl J; Uusimaa, Johanna

    2015-05-01

    Sodium valproate (VPA) is a potentially hepatotoxic antiepileptic drug. Risk of VPA-induced hepatotoxicity is increased in patients with mitochondrial diseases and especially in patients with POLG1 gene mutations. We used a HepG2 cell in vitro model to investigate the effect of VPA on mitochondrial activity. Cells were incubated in glucose medium and mitochondrial respiration-inducing medium supplemented with galactose and pyruvate. VPA treatments were carried out at concentrations of 0-2.0mM for 24-72 h. In both media, VPA caused decrease in oxygen consumption rates and mitochondrial membrane potential. VPA exposure led to depleted ATP levels in HepG2 cells incubated in galactose medium suggesting dysfunction in mitochondrial ATP production. In addition, VPA exposure for 72 h increased levels of mitochondrial reactive oxygen species (ROS), but adversely decreased protein levels of mitochondrial superoxide dismutase SOD2, suggesting oxidative stress caused by impaired elimination of mitochondrial ROS and a novel pathomechanism related to VPA toxicity. Increased cell death and decrease in cell number was detected under both metabolic conditions. However, immunoblotting did not show any changes in the protein levels of the catalytic subunit A of mitochondrial DNA polymerase γ, the mitochondrial respiratory chain complexes I, II and IV, ATP synthase, E3 subunit dihydrolipoyl dehydrogenase of pyruvate dehydrogenase, 2-oxoglutarate dehydrogenase and glutathione peroxidase. Our results show that VPA inhibits mitochondrial respiration and leads to mitochondrial dysfunction, oxidative stress and increased cell death, thus suggesting an essential role of mitochondria in VPA-induced hepatotoxicity.

  11. Mitochondrial transfer from Wharton's jelly-derived mesenchymal stem cells to mitochondria-defective cells recaptures impaired mitochondrial function.

    PubMed

    Lin, Hung-Yu; Liou, Chia-Wei; Chen, Shang-Der; Hsu, Te-Yao; Chuang, Jiin-Haur; Wang, Pei-Wen; Huang, Sheng-Teng; Tiao, Mao-Meng; Chen, Jin-Bor; Lin, Tsu-Kung; Chuang, Yao-Chung

    2015-05-01

    Adult mesenchymal stem cell (MSC)-conducted mitochondrial transfer has been recently shown to rescue cellular bioenergetics and prevent cell death caused by mitochondrial dysfunction. Wharton's jelly-derived MSCs (WJMSCs) harvested from postpartum umbilical cords are an accessible and abundant source of stem cells. This study aimed to determine the capability of WJMSCs to transfer their own mitochondria and rescue impaired oxidative phosphorylation (OXPHOS) and bioenergetics caused by mitochondrial DNA defects. To do this, WJMSCs were co-cultured with mitochondrial DNA (mtDNA)-depleted ρ(0) cells and the recapture of mitochondrial function was evaluated. WJMSCs were shown to be capable of transferring their own mitochondria into ρ(0) cells and underwent interorganellar mixture within these cells. Permissive culture media (BrdU-containing and pyruvate- and uridine-free) sieved out a survival cell population from the co-cultured WJMSCs (BrdU-sensitive) and ρ(0) cells (pyruvate/uridine-free). The survival cells had mtDNA identical to that of WJMSCs, whereas they expressed cellular markers identical to that of ρ(0) cells. Importantly, these ρ(0)-plus -WJMSC-mtDNA (ρ(+W)) cells recovered the expression of mtDNA-encoded proteins and exhibited functional oxygen consumption and respiratory control, as well as the activity of electron transport chain (ETC) complexes I, II, III and IV. In addition, ETC complex V-inhibitor-sensitive ATP production and metabolic shifting were also recovered. Furthermore, cellular behaviors including attachment-free proliferation, aerobic viability and OXPHOS-reliant cellular motility were also regained after mitochondrial transfer by WJMSCs. The therapeutic effect of WJMSCs-derived mitochondrial transfer was able to stably sustain for at least 45 passages. In conclusion, this study suggests that WJMSCs may serve as a potential therapeutic strategy for diseases linked to mitochondrial dysfunction through the donation of healthy

  12. How mitochondrial dynamism orchestrates mitophagy

    PubMed Central

    Shirihai, Orian; Song, Moshi; Dorn, Gerald W

    2015-01-01

    Mitochondria are highly dynamic, except in adult cardiomyocytes. Yet, the fission and fusion-promoting proteins that mediate mitochondrial dynamism are highly expressed in, and essential to the normal functioning of, hearts. Here, we review accumulating evidence supporting important roles for mitochondrial fission and fusion in cardiac mitochondrial quality control, focusing on the PINK1-Parkin mitophagy pathway.Based in part on recent findings from in vivo mouse models in which mitofusin-mediated mitochondrial fusion or Drp1-mediated mitochondrial fission were conditionally interrupted in cardiac myocytes, we propose several new concepts that may provide insight into the cardiac mitochondrial dynamism-mitophagy interactome. PMID:25999423

  13. Sudden Infant Death Syndrome

    MedlinePlus

    Sudden infant death syndrome (SIDS) is the sudden, unexplained death of an infant younger than one year old. Some people call ... boys, African Americans, and American Indian/Alaska Native infants have a higher risk of SIDS. Although health ...

  14. The Spectrum of Mitochondrial Ultrastructural Defects in Mitochondrial Myopathy.

    PubMed

    Vincent, Amy E; Ng, Yi Shiau; White, Kathryn; Davey, Tracey; Mannella, Carmen; Falkous, Gavin; Feeney, Catherine; Schaefer, Andrew M; McFarland, Robert; Gorman, Grainne S; Taylor, Robert W; Turnbull, Doug M; Picard, Martin

    2016-01-01

    Mitochondrial functions are intrinsically linked to their morphology and membrane ultrastructure. Characterizing abnormal mitochondrial structural features may thus provide insight into the underlying pathogenesis of inherited and acquired mitochondrial diseases. Following a systematic literature review on ultrastructural defects in mitochondrial myopathy, we investigated skeletal muscle biopsies from seven subjects with genetically defined mtDNA mutations. Mitochondrial ultrastructure and morphology were characterized using two complimentary approaches: transmission electron microscopy (TEM) and serial block face scanning EM (SBF-SEM) with 3D reconstruction. Six ultrastructural abnormalities were identified including i) paracrystalline inclusions, ii) linearization of cristae and abnormal angular features, iii) concentric layering of cristae membranes, iv) matrix compartmentalization, v) nanotunelling, and vi) donut-shaped mitochondria. In light of recent molecular advances in mitochondrial biology, these findings reveal novel aspects of mitochondrial ultrastructure and morphology in human tissues with implications for understanding the mechanisms linking mitochondrial dysfunction to disease. PMID:27506553

  15. The Spectrum of Mitochondrial Ultrastructural Defects in Mitochondrial Myopathy

    PubMed Central

    Vincent, Amy E.; Ng, Yi Shiau; White, Kathryn; Davey, Tracey; Mannella, Carmen; Falkous, Gavin; Feeney, Catherine; Schaefer, Andrew M.; McFarland, Robert; Gorman, Grainne S.; Taylor, Robert W.; Turnbull, Doug M.; Picard, Martin

    2016-01-01

    Mitochondrial functions are intrinsically linked to their morphology and membrane ultrastructure. Characterizing abnormal mitochondrial structural features may thus provide insight into the underlying pathogenesis of inherited and acquired mitochondrial diseases. Following a systematic literature review on ultrastructural defects in mitochondrial myopathy, we investigated skeletal muscle biopsies from seven subjects with genetically defined mtDNA mutations. Mitochondrial ultrastructure and morphology were characterized using two complimentary approaches: transmission electron microscopy (TEM) and serial block face scanning EM (SBF-SEM) with 3D reconstruction. Six ultrastructural abnormalities were identified including i) paracrystalline inclusions, ii) linearization of cristae and abnormal angular features, iii) concentric layering of cristae membranes, iv) matrix compartmentalization, v) nanotunelling, and vi) donut-shaped mitochondria. In light of recent molecular advances in mitochondrial biology, these findings reveal novel aspects of mitochondrial ultrastructure and morphology in human tissues with implications for understanding the mechanisms linking mitochondrial dysfunction to disease. PMID:27506553

  16. NDE1 and GSK3β Associate with TRAK1 and Regulate Axonal Mitochondrial Motility: Identification of Cyclic AMP as a Novel Modulator of Axonal Mitochondrial Trafficking.

    PubMed

    Ogawa, Fumiaki; Murphy, Laura C; Malavasi, Elise L V; O'Sullivan, Shane T; Torrance, Helen S; Porteous, David J; Millar, J Kirsty

    2016-05-18

    Mitochondria are essential for neuronal function, providing the energy required to power neurotransmission, and fulfilling many important additional roles. In neurons, mitochondria must be efficiently transported to sites, including synapses, where their functions are required. Neurons, with their highly elongated morphology, are consequently extremely sensitive to defective mitochondrial trafficking which can lead to neuronal ill-health/death. We recently demonstrated that DISC1 associates with mitochondrial trafficking complexes where it associates with the core kinesin and dynein adaptor molecule TRAK1. We now show that the DISC1 interactors NDE1 and GSK3β also associate robustly with TRAK1 and demonstrate that NDE1 promotes retrograde axonal mitochondrial movement. GSK3β is known to modulate axonal mitochondrial motility, although reports of its actual effect are conflicting. We show that, in our system, GSK3β promotes anterograde mitochondrial transport. Finally, we investigated the influence of cAMP elevation upon mitochondrial motility, and found a striking increase in mitochondrial motility and retrograde movement. DISC1, NDE1, and GSK3β are implicated as risk factors for major mental illness. Our demonstration that they function together within mitochondrial trafficking complexes suggests that defective mitochondrial transport may be a contributory disease mechanism in some cases of psychiatric disorder. PMID:26815013

  17. Suicide on death row.

    PubMed

    Lester, David; Tartaro, Christine

    2002-09-01

    The suicide rate on death row for the period 1976 through 1999 was found to be high (113 per 100,000 per year), some five times higher than the suicide rate for the male population of the United States. The death row suicide rate was predicted by features of the death row population (negatively with the population on death row) and by social indicators of the society as a whole (negatively with birth and divorce rates and positively with marriage rates).

  18. No life without death.

    PubMed

    Krammer, Peter H; Kamiński, Marcin; Kiessling, Michael; Gülow, Karsten

    2007-01-01

    Apoptosis-programed cell death-is the most common form of death in the body. Once apoptosis is induced, proper execution of the cell death program requires the coordinated activation and execution of multiple molecular processes. Here, we describe the pathways and the basic components of the death-inducing machinery. Since apoptosis is a key regulator of tissue homeostasis, an imbalance of apoptosis results in severe diseases like cancer, autoimmunity, and AIDS.

  19. Impaired mitochondrial function in microvesicular steatosis. Effects of drugs, ethanol, hormones and cytokines.

    PubMed

    Fromenty, B; Pessayre, D

    1997-01-01

    Microvesicular steatosis occurs in conditions characterized by severe impairment of the mitochondrial beta-oxidation process, due to genetic and/or acquired causes. Drugs and some endogenous compounds can sequester coenzyme A (aspirin, valproic acid), inhibit mitochondrial beta-oxidation enzymes (tetracyclines, several 2-arylpropionate anti-inflammatory drugs, amineptine and tianeptine), or inhibit both mitochondrial beta-oxidation and oxidative phosphorylation (endogenous bile acids, amiodarone, perhexiline and diethylaminoethoxyhexestrol), while female sex hormones have complex, but moderate, effects on mitochondrial structure and function. Other substances impair mitochondrial DNA transcription (interferon-alpha) or mitochondrial DNA replication (dideoxynucleosides), while alcohol abuse might accelerate the normal oxidative aging of mitochondrial DNA. When beta-oxidation is severely impaired, fatty acids, which are poorly oxidized by mitochondria, are mainly esterified into triglycerides, but there is a residual increase in non-esterified fatty acids. Triglycerides (possibly emulsified by a rim of non-esterified fatty acids) accumulate as small vesicles. Impairment of energy production, and the mitochondrial and general toxicity of both non-esterified fatty acids and dicarboxylic acids, may contribute to liver failure, coma and death in severe forms. Although milder forms of microvesicular steatosis have a good short-term prognosis, they can lead to chronic lipid peroxidation and the development of steatohepatitis lesions. Investigational molecules with a carboxylic group or a protonatable amine, or those which might interfere with mitochondrial DNA, should be screened for possible mitochondrial effects.

  20. Reduced calcium-dependent mitochondrial damage underlies the reduced vulnerability of excitotoxicity-tolerant hippocampal neurons.

    PubMed

    Pivovarova, Natalia B; Stanika, Ruslan I; Watts, Charlotte A; Brantner, Christine A; Smith, Carolyn L; Andrews, S Brian

    2008-03-01

    In central neurons, over-stimulation of NMDA receptors leads to excessive mitochondrial calcium accumulation and damage, which is a critical step in excitotoxic death. This raises the possibility that low susceptibility to calcium overload-induced mitochondrial damage might characterize excitotoxicity-resistant neurons. In this study, we have exploited two complementary models of preconditioning-induced excitotoxicity resistance to demonstrate reduced calcium-dependent mitochondrial damage in NMDA-tolerant hippocampal neurons. We have further identified adaptations in mitochondrial calcium handling that account for enhanced mitochondrial integrity. In both models, enhanced tolerance was associated with improved preservation of mitochondrial membrane potential and structure. In the first model, which exhibited modest neuroprotection, mitochondria-dependent calcium deregulation was delayed, even though cytosolic and mitochondrial calcium loads were quantitatively unchanged, indicating that enhanced mitochondrial calcium capacity accounts for reduced injury. In contrast, the second model, which exhibited strong neuroprotection, displayed further delayed calcium deregulation and reduced mitochondrial damage because downregulation of NMDA receptor surface expression depressed calcium loading. Reducing calcium entry also modified the chemical composition of the calcium-buffering precipitates that form in calcium-loaded mitochondria. It thus appears that reduced mitochondrial calcium loading is a major factor underlying the robust neuroprotection seen in highly tolerant cells. PMID:18036152

  1. Mitochondrial Ca2+ Overload Underlies Aβ Oligomers Neurotoxicity Providing an Unexpected Mechanism of Neuroprotection by NSAIDs

    PubMed Central

    Sanz-Blasco, Sara; Valero, Ruth A.; Rodríguez-Crespo, Ignacio; Villalobos, Carlos; Núñez, Lucía

    2008-01-01

    Dysregulation of intracellular Ca2+ homeostasis may underlie amyloid β peptide (Aβ) toxicity in Alzheimer's Disease (AD) but the mechanism is unknown. In search for this mechanism we found that Aβ1–42 oligomers, the assembly state correlating best with cognitive decline in AD, but not Aβ fibrils, induce a massive entry of Ca2+ in neurons and promote mitochondrial Ca2+ overload as shown by bioluminescence imaging of targeted aequorin in individual neurons. Aβ oligomers induce also mitochondrial permeability transition, cytochrome c release, apoptosis and cell death. Mitochondrial depolarization prevents mitochondrial Ca2+ overload, cytochrome c release and cell death. In addition, we found that a series of non-steroidal anti-inflammatory drugs (NSAIDs) including salicylate, sulindac sulfide, indomethacin, ibuprofen and R-flurbiprofen depolarize mitochondria and inhibit mitochondrial Ca2+ overload, cytochrome c release and cell death induced by Aβ oligomers. Our results indicate that i) mitochondrial Ca2+ overload underlies the neurotoxicity induced by Aβ oligomers and ii) inhibition of mitochondrial Ca2+ overload provides a novel mechanism of neuroprotection by NSAIDs against Aβ oligomers and AD. PMID:18648507

  2. Mitochondrial function is altered in horse atypical myopathy.

    PubMed

    Lemieux, Hélène; Boemer, François; van Galen, Gaby; Serteyn, Didier; Amory, Hélène; Baise, Etienne; Cassart, Dominique; van Loon, Gunther; Marcillaud-Pitel, Christel; Votion, Dominique-M

    2016-09-01

    Equine atypical myopathy in Europe is a fatal rhabdomyolysis syndrome that results from the ingestion of hypoglycin A contained in seeds and seedlings of Acer pseudoplatanus (sycamore maple). Acylcarnitine concentrations in serum and muscle OXPHOS capacity were determined in 15 atypical myopathy cases. All but one acylcarnitine were out of reference range and mitochondrial respiratory capacity was severely decreased up to 49% as compared to 10 healthy controls. The hallmark of atypical myopathy thus consists of a severe alteration in the energy metabolism including a severe impairment in muscle mitochondrial respiration that could contribute to its high death rate. PMID:27374763

  3. Mitochondrial Dysfunction in Cancer

    PubMed Central

    Boland, Michelle L.; Chourasia, Aparajita H.; Macleod, Kay F.

    2013-01-01

    A mechanistic understanding of how mitochondrial dysfunction contributes to cell growth and tumorigenesis is emerging beyond Warburg as an area of research that is under-explored in terms of its significance for clinical management of cancer. Work discussed in this review focuses less on the Warburg effect and more on mitochondria and how dysfunctional mitochondria modulate cell cycle, gene expression, metabolism, cell viability, and other established aspects of cell growth and stress responses. There is increasing evidence that key oncogenes and tumor suppressors modulate mitochondrial dynamics through important signaling pathways and that mitochondrial mass and function vary between tumors and individuals but the significance of these events for cancer are not fully appreciated. We explore the interplay between key molecules involved in mitochondrial fission and fusion and in apoptosis, as well as in mitophagy, biogenesis, and spatial dynamics of mitochondria and consider how these distinct mechanisms are coordinated in response to physiological stresses such as hypoxia and nutrient deprivation. Importantly, we examine how deregulation of these processes in cancer has knock on effects for cell proliferation and growth. We define major forms of mitochondrial dysfunction and address the extent to which the functional consequences of such dysfunction can be determined and exploited for cancer diagnosis and treatment. PMID:24350057

  4. Dreams of Death.

    ERIC Educational Resources Information Center

    Barrett, Deirdre

    1989-01-01

    Examined frequency and characteristics of overt dreams of dying among healthy young adults. Dreams of dying were found to be rare but distinctive content category, representing overwhelmingly pleasant dreams. Over one-half of death dreams involved lengthy afterlife sequence, remainder focused on process of death. Death dreams of these healthy…

  5. Analysis of mitochondrial dynamics and functions using imaging approaches

    PubMed Central

    Mitra, Kasturi; Lippincott-Schwartz, Jennifer

    2010-01-01

    Mitochondria are organelles that have been primarily known as the ‘power house of the cell’. However, recent advances in the field have revealed that mitochondria are also involved in many other cellular activities like lipid modifications, redox balance, calcium balance and even control cell death. These multifunctional organelles are motile and highly dynamic in shapes and forms; the dynamism is brought about by the mitochondria's ability to undergo fission and fusion with each other. Therefore it is very important to be able to image mitochondrial shape changes to relate to the variety of cellular functions these organelles have to accomplish. The protocols mentioned here will enable researchers to perform steady state and time lapse imaging of mitochondria in live cells by using confocal microscopy. High resolution 3D imaging of mitochondria will not only be helpful in understanding mitochondrial structure in detail but also could be used to analyze their structural relationships with other organelles in the cell. FRAP (fluorescence recovery after photobleaching) studies can be performed to understand mitochondrial dynamics or dynamics of any mitochondrial molecule within the organelle. Microirradiation assay can be performed to study functional continuity between mitochondria. Protocol for measuring mitochondrial potential has also been included in this chapter. In conclusion, the protocols described here will aid the understanding of mitochondrial structure-function relationship. PMID:20235105

  6. Mitochondrial cereblon functions as a Lon-type protease.

    PubMed

    Kataoka, Kosuke; Nakamura, China; Asahi, Toru; Sawamura, Naoya

    2016-07-15

    Lon protease plays a major role in the protein quality control system in mammalian cell mitochondria. It is present in the mitochondrial matrix, and degrades oxidized and misfolded proteins, thereby protecting the cell from various extracellular stresses, including oxidative stress. The intellectual disability-associated and thalidomide-binding protein cereblon (CRBN) contains a large, highly conserved Lon domain. However, whether CRBN has Lon protease-like function remains unknown. Here, we determined if CRBN has a protective function against oxidative stress, similar to Lon protease. We report that CRBN partially distributes in mitochondria, suggesting it has a mitochondrial function. To specify the mitochondrial role of CRBN, we mitochondrially expressed CRBN in human neuroblastoma SH-SY5Y cells. The resulting stable SH-SY5Y cell line showed no apparent effect on the mitochondrial functions of fusion, fission, and membrane potential. However, mitochondrially expressed CRBN exhibited protease activity, and was induced by oxidative stress. In addition, stably expressed cells exhibited suppressed neuronal cell death induced by hydrogen peroxide. These results suggest that CRBN functions specifically as a Lon-type protease in mitochondria.

  7. Mitochondrial cereblon functions as a Lon-type protease

    PubMed Central

    Kataoka, Kosuke; Nakamura, China; Asahi, Toru; Sawamura, Naoya

    2016-01-01

    Lon protease plays a major role in the protein quality control system in mammalian cell mitochondria. It is present in the mitochondrial matrix, and degrades oxidized and misfolded proteins, thereby protecting the cell from various extracellular stresses, including oxidative stress. The intellectual disability-associated and thalidomide-binding protein cereblon (CRBN) contains a large, highly conserved Lon domain. However, whether CRBN has Lon protease-like function remains unknown. Here, we determined if CRBN has a protective function against oxidative stress, similar to Lon protease. We report that CRBN partially distributes in mitochondria, suggesting it has a mitochondrial function. To specify the mitochondrial role of CRBN, we mitochondrially expressed CRBN in human neuroblastoma SH-SY5Y cells. The resulting stable SH-SY5Y cell line showed no apparent effect on the mitochondrial functions of fusion, fission, and membrane potential. However, mitochondrially expressed CRBN exhibited protease activity, and was induced by oxidative stress. In addition, stably expressed cells exhibited suppressed neuronal cell death induced by hydrogen peroxide. These results suggest that CRBN functions specifically as a Lon-type protease in mitochondria. PMID:27417535

  8. Mitochondrial fusion and inheritance of the mitochondrial genome.

    PubMed

    Takano, Hiroyoshi; Onoue, Kenta; Kawano, Shigeyuki

    2010-03-01

    Although maternal or uniparental inheritance of mitochondrial genomes is a general rule, biparental inheritance is sometimes observed in protists and fungi,including yeasts. In yeast, recombination occurs between the mitochondrial genomes inherited from both parents.Mitochondrial fusion observed in yeast zygotes is thought to set up a space for DNA recombination. In the last decade,a universal mitochondrial fusion mechanism has been uncovered, using yeast as a model. On the other hand, an alternative mitochondrial fusion mechanism has been identified in the true slime mold Physarum polycephalum.A specific mitochondrial plasmid, mF, has been detected as the genetic material that causes mitochondrial fusion in P. polycephalum. Without mF, fusion of the mitochondria is not observed throughout the life cycle, suggesting that Physarum has no constitutive mitochondrial fusion mechanism.Conversely, mitochondria fuse in zygotes and during sporulation with mF. The complete mF sequence suggests that one gene, ORF640, encodes a fusogen for Physarum mitochondria. Although in general, mitochondria are inherited uniparentally, biparental inheritance occurs with specific sexual crossing in P. polycephalum.An analysis of the transmission of mitochondrial genomes has shown that recombinations between two parental mitochondrial genomes require mitochondrial fusion,mediated by mF. Physarum is a unique organism for studying mitochondrial fusion. PMID:20196232

  9. Mitochondrial fusion and inheritance of the mitochondrial genome.

    PubMed

    Takano, Hiroyoshi; Onoue, Kenta; Kawano, Shigeyuki

    2010-03-01

    Although maternal or uniparental inheritance of mitochondrial genomes is a general rule, biparental inheritance is sometimes observed in protists and fungi,including yeasts. In yeast, recombination occurs between the mitochondrial genomes inherited from both parents.Mitochondrial fusion observed in yeast zygotes is thought to set up a space for DNA recombination. In the last decade,a universal mitochondrial fusion mechanism has been uncovered, using yeast as a model. On the other hand, an alternative mitochondrial fusion mechanism has been identified in the true slime mold Physarum polycephalum.A specific mitochondrial plasmid, mF, has been detected as the genetic material that causes mitochondrial fusion in P. polycephalum. Without mF, fusion of the mitochondria is not observed throughout the life cycle, suggesting that Physarum has no constitutive mitochondrial fusion mechanism.Conversely, mitochondria fuse in zygotes and during sporulation with mF. The complete mF sequence suggests that one gene, ORF640, encodes a fusogen for Physarum mitochondria. Although in general, mitochondria are inherited uniparentally, biparental inheritance occurs with specific sexual crossing in P. polycephalum.An analysis of the transmission of mitochondrial genomes has shown that recombinations between two parental mitochondrial genomes require mitochondrial fusion,mediated by mF. Physarum is a unique organism for studying mitochondrial fusion.

  10. The acylphloroglucinols hyperforin and myrtucommulone A cause mitochondrial dysfunctions in leukemic cells by direct interference with mitochondria.

    PubMed

    Wiechmann, Katja; Müller, Hans; Fischer, Dagmar; Jauch, Johann; Werz, Oliver

    2015-11-01

    The acylphloroglucinols hyperforin (Hypf) and myrtucommulone A (MC A) induce death of cancer cells by triggering the intrinsic/mitochondrial pathway of apoptosis, accompanied by a loss of the mitochondrial membrane potential and release of cytochrome c. However, the upstream targets and mechanisms leading to these mitochondrial events in cancer cells remain elusive. Here we show that Hypf and MC A directly act on mitochondria derived from human leukemic HL-60 cells and thus, disrupt mitochondrial functions. In isolated mitochondria, Hypf and MC A efficiently impaired mitochondrial viability (EC50 = 0.2 and 0.9 µM, respectively), caused loss of the mitochondrial membrane potential (at 0.03 and 0.1 µM, respectively), and suppressed mitochondrial ATP synthesis (IC50 = 0.2 and 0.5 µM, respectively). Consequently, the compounds activated the adenosine monophosphate-activated protein kinase (AMPK) in HL-60 cells, a cellular energy sensor involved in apoptosis of cancer cells. Side by side comparison with the protonophore CCCP and the ATP synthase inhibitor oligomycin suggest that Hypf and MC A act as protonophores that primarily dissipate the mitochondrial membrane potential by direct interaction with the mitochondrial membrane. Together, Hypf and MC A abolish the mitochondrial proton motive force that on one hand impairs mitochondrial viability and on the other cause activation of AMPK due to lowered ATP levels which may further facilitate the intrinsic mitochondrial pathway of apoptosis.

  11. The acylphloroglucinols hyperforin and myrtucommulone A cause mitochondrial dysfunctions in leukemic cells by direct interference with mitochondria.

    PubMed

    Wiechmann, Katja; Müller, Hans; Fischer, Dagmar; Jauch, Johann; Werz, Oliver

    2015-11-01

    The acylphloroglucinols hyperforin (Hypf) and myrtucommulone A (MC A) induce death of cancer cells by triggering the intrinsic/mitochondrial pathway of apoptosis, accompanied by a loss of the mitochondrial membrane potential and release of cytochrome c. However, the upstream targets and mechanisms leading to these mitochondrial events in cancer cells remain elusive. Here we show that Hypf and MC A directly act on mitochondria derived from human leukemic HL-60 cells and thus, disrupt mitochondrial functions. In isolated mitochondria, Hypf and MC A efficiently impaired mitochondrial viability (EC50 = 0.2 and 0.9 µM, respectively), caused loss of the mitochondrial membrane potential (at 0.03 and 0.1 µM, respectively), and suppressed mitochondrial ATP synthesis (IC50 = 0.2 and 0.5 µM, respectively). Consequently, the compounds activated the adenosine monophosphate-activated protein kinase (AMPK) in HL-60 cells, a cellular energy sensor involved in apoptosis of cancer cells. Side by side comparison with the protonophore CCCP and the ATP synthase inhibitor oligomycin suggest that Hypf and MC A act as protonophores that primarily dissipate the mitochondrial membrane potential by direct interaction with the mitochondrial membrane. Together, Hypf and MC A abolish the mitochondrial proton motive force that on one hand impairs mitochondrial viability and on the other cause activation of AMPK due to lowered ATP levels which may further facilitate the intrinsic mitochondrial pathway of apoptosis. PMID:26386573

  12. Adult-onset mitochondrial myopathy.

    PubMed Central

    Fernandez-Sola, J.; Casademont, J.; Grau, J. M.; Graus, F.; Cardellach, F.; Pedrol, E.; Urbano-Marquez, A.

    1992-01-01

    Mitochondrial diseases are polymorphic entities which may affect many organs and systems. Skeletal muscle involvement is frequent in the context of systemic mitochondrial disease, but adult-onset pure mitochondrial myopathy appears to be rare. We report 3 patients with progressive skeletal mitochondrial myopathy starting in adult age. In all cases, the proximal myopathy was the only clinical feature. Mitochondrial pathology was confirmed by evidence of ragged-red fibres in muscle histochemistry, an abnormal mitochondrial morphology in electron microscopy and by exclusion of other underlying diseases. No deletions of mitochondrial DNA were found. We emphasize the need to look for a mitochondrial disorder in some non-specific myopathies starting in adult life. Images Figure 1 Figure 2 PMID:1589382

  13. Renal Mitochondrial Cytopathies

    PubMed Central

    Emma, Francesco; Montini, Giovanni; Salviati, Leonardo; Dionisi-Vici, Carlo

    2011-01-01

    Renal diseases in mitochondrial cytopathies are a group of rare diseases that are characterized by frequent multisystemic involvement and extreme variability of phenotype. Most frequently patients present a tubular defect that is consistent with complete De Toni-Debré-Fanconi syndrome in most severe forms. More rarely, patients present with chronic tubulointerstitial nephritis, cystic renal diseases, or primary glomerular involvement. In recent years, two clearly defined entities, namely 3243 A > G tRNALEU mutations and coenzyme Q10 biosynthesis defects, have been described. The latter group is particularly important because it represents the only treatable renal mitochondrial defect. In this paper, the physiopathologic bases of mitochondrial cytopathies, the diagnostic approaches, and main characteristics of related renal diseases are summarized. PMID:21811680

  14. Cancer: Mitochondrial Origins.

    PubMed

    Stefano, George B; Kream, Richard M

    2015-12-01

    The primacy of glucose derived from photosynthesis as an existential source of chemical energy across plant and animal phyla is universally accepted as a core principle in the biological sciences. In mammalian cells, initial processing of glucose to triose phosphate intermediates takes place within the cytosolic glycolytic pathway and terminates with temporal transport of reducing equivalents derived from pyruvate metabolism by membrane-associated respiratory complexes in the mitochondrial matrix. The intra-mitochondrial availability of molecular oxygen as the ultimate electron acceptor drives the evolutionary fashioned chemiosmotic production of ATP as a high-efficiency biological process. The mechanistic bases of carcinogenesis have demonstrated profound alteration of normative mitochondrial function, notably dysregulated respiratory processes. Accordingly, the classic Warburg effect functionally links aerobic glycolysis, aberrant production and release of lactate, and metabolic down-regulation of mitochondrial oxidative processes with the carcinogenetic phenotype. We surmise, however, that aerobic fermentation by cancer cells may also represent a developmental re-emergence of an evolutionarily conserved early phenotype, which was "sidelined" with the emergence of mitochondrial oxidative phosphorylation as a primary mechanism for ATP production in normal cells. Regardless of state-dependent physiological status in mixed populations of cancer cells, it has been established that mitochondria are functionally linked to the initiation of cancer and its progression. Biochemical, molecular, and physiological differences in cancer cell mitochondria, notably mtDNA heteroplasmy and allele-specific expression of selected nuclear genes, may represent major focal points for novel targeting and elimination of cancer cells in metastatic disease afflicting human populations. To date, and despite considerable research efforts, the practical realization of advanced mitochondrial

  15. Cancer: Mitochondrial Origins

    PubMed Central

    Stefano, George B.; Kream, Richard M.

    2015-01-01

    The primacy of glucose derived from photosynthesis as an existential source of chemical energy across plant and animal phyla is universally accepted as a core principle in the biological sciences. In mammalian cells, initial processing of glucose to triose phosphate intermediates takes place within the cytosolic glycolytic pathway and terminates with temporal transport of reducing equivalents derived from pyruvate metabolism by membrane-associated respiratory complexes in the mitochondrial matrix. The intra-mitochondrial availability of molecular oxygen as the ultimate electron acceptor drives the evolutionary fashioned chemiosmotic production of ATP as a high-efficiency biological process. The mechanistic bases of carcinogenesis have demonstrated profound alteration of normative mitochondrial function, notably dysregulated respiratory processes. Accordingly, the classic Warburg effect functionally links aerobic glycolysis, aberrant production and release of lactate, and metabolic down-regulation of mitochondrial oxidative processes with the carcinogenetic phenotype. We surmise, however, that aerobic fermentation by cancer cells may also represent a developmental re-emergence of an evolutionarily conserved early phenotype, which was “sidelined” with the emergence of mitochondrial oxidative phosphorylation as a primary mechanism for ATP production in normal cells. Regardless of state-dependent physiological status in mixed populations of cancer cells, it has been established that mitochondria are functionally linked to the initiation of cancer and its progression. Biochemical, molecular, and physiological differences in cancer cell mitochondria, notably mtDNA heteroplasmy and allele-specific expression of selected nuclear genes, may represent major focal points for novel targeting and elimination of cancer cells in metastatic disease afflicting human populations. To date, and despite considerable research efforts, the practical realization of advanced

  16. The Moldovan experience of maternal death reviews.

    PubMed

    Hodorogea, S; Friptu, V

    2014-09-01

    A Confidential Enquiry into Maternal Deaths is an anonymous, multidisciplinary and systematic review of all cases of maternal mortality. This paper describes one such process implemented at national level in Moldova. Its aim was to conduct an in-depth review of the underlying causes and circumstances surrounding each mother's death to learn lessons to improve care in future. Its findings showed that deaths were predominantly due to direct obstetric causes, especially haemorrhage and sepsis, and adverse social determinants, particularly poverty and migration also played a decisive role in more than half of the cases. The final report identified potentially remediable actions and the key areas requiring interventions by the health sector, administrators and the community. Its recommendations have enabled the implementation of some solutions to help prevent future maternal deaths, including the development of evidence-based clinical guidelines. PMID:25236639

  17. Discretionary death: conditions, dilemmas, and normative regulation.

    PubMed

    Machado, Nora

    2005-11-01

    The author examines a major shift in the conceptualization and practices relating to death and dying in Western and other societies with advanced medicine. This shift is the result of socio-technical and cultural developments characterized by but not limited to the routine widespread application of life support technologies in the hospital together with notions of increased patient rights. It has resulted in a class of end-of-life situations, which the author defines as "discretionary death." The concept of discretionary death underscores the role of contextual and discretionary factors in end-of-life decision-making. The author identifies and discusses the necessary and complex process of norm formation that informs and regulates end-of-life medical practice and establishes societal consensus across society with respect to legitimizing "discretionary death."

  18. The Moldovan experience of maternal death reviews.

    PubMed

    Hodorogea, S; Friptu, V

    2014-09-01

    A Confidential Enquiry into Maternal Deaths is an anonymous, multidisciplinary and systematic review of all cases of maternal mortality. This paper describes one such process implemented at national level in Moldova. Its aim was to conduct an in-depth review of the underlying causes and circumstances surrounding each mother's death to learn lessons to improve care in future. Its findings showed that deaths were predominantly due to direct obstetric causes, especially haemorrhage and sepsis, and adverse social determinants, particularly poverty and migration also played a decisive role in more than half of the cases. The final report identified potentially remediable actions and the key areas requiring interventions by the health sector, administrators and the community. Its recommendations have enabled the implementation of some solutions to help prevent future maternal deaths, including the development of evidence-based clinical guidelines.

  19. Late Mitochondrial Acquisition, Really?

    PubMed Central

    Degli Esposti, Mauro

    2016-01-01

    This article provides a timely critique of a recent Nature paper by Pittis and Gabaldón that has suggested a late origin of mitochondria in eukaryote evolution. It shows that the inferred ancestry of many mitochondrial proteins has been incorrectly assigned by Pittis and Gabaldón to bacteria other than the aerobic proteobacteria from which the ancestor of mitochondria originates, thereby questioning the validity of their suggestion that mitochondrial acquisition may be a late event in eukaryote evolution. The analysis and approach presented here may guide future studies to resolve the true ancestry of mitochondria. PMID:27289097

  20. Autophagy prevents autophagic cell death in Tetrahymena in response to oxidative stress.

    PubMed

    Zhang, Si-Wei; Feng, Jiang-Nan; Cao, Yi; Meng, Li-Ping; Wang, Shu-Lin

    2015-05-18

    Autophagy is a major cellular pathway used to degrade long-lived proteins or organelles that may be damaged due to increased reactive oxygen species (ROS) generated by cellular stress. Autophagy typically enhances cell survival, but it may also act to promote cell death under certain conditions. The mechanism underlying this paradox, however, remains unclear. We showed that Tetrahymena cells exerted increased membrane-bound vacuoles characteristic of autophagy followed by autophagic cell death (referred to as cell death with autophagy) after exposure to hydrogen peroxide. Inhibition of autophagy by chloroquine or 3-methyladenine significantly augmented autophagic cell death induced by hydrogen peroxide. Blockage of the mitochondrial electron transport chain or starvation triggered activation of autophagy followed by cell death by inducing the production of ROS due to the loss of mitochondrial membrane potential. This indicated a regulatory role of mitochondrial ROS in programming autophagy and autophagic cell death in Tetrahymena. Importantly, suppression of autophagy enhanced autophagic cell death in Tetrahymena in response to elevated ROS production from starvation, and this was reversed by antioxidants. Therefore, our results suggest that autophagy was activated upon oxidative stress to prevent the initiation of autophagic cell death in Tetrahymena until the accumulation of ROS passed the point of no return, leading to delayed cell death in Tetrahymena.

  1. Autophagy prevents autophagic cell death in Tetrahymena in response to oxidative stress

    PubMed Central

    ZHANG, Si-Wei; FENG, Jiang-Nan; CAO, Yi; MENG, Li-Ping; WANG, Shu-Lin

    2015-01-01

    Autophagy is a major cellular pathway used to degrade long-lived proteins or organelles that may be damaged due to increased reactive oxygen species (ROS) generated by cellular stress. Autophagy typically enhances cell survival, but it may also act to promote cell death under certain conditions. The mechanism underlying this paradox, however, remains unclear. We showed that Tetrahymena cells exerted increased membrane-bound vacuoles characteristic of autophagy followed by autophagic cell death (referred to as cell death with autophagy) after exposure to hydrogen peroxide. Inhibition of autophagy by chloroquine or 3-methyladenine significantly augmented autophagic cell death induced by hydrogen peroxide. Blockage of the mitochondrial electron transport chain or starvation triggered activation of autophagy followed by cell death by inducing the production of ROS due to the loss of mitochondrial membrane potential. This indicated a regulatory role of mitochondrial ROS in programming autophagy and autophagic cell death in Tetrahymena. Importantly, suppression of autophagy enhanced autophagic cell death in Tetrahymena in response to elevated ROS production from starvation, and this was reversed by antioxidants. Therefore, our results suggest that autophagy was activated upon oxidative stress to prevent the initiation of autophagic cell death in Tetrahymena until the accumulation of ROS passed the point of no return, leading to delayed cell death in Tetrahymena. PMID:26018860

  2. Pharmacologic Effects on Mitochondrial Function

    ERIC Educational Resources Information Center

    Cohen, Bruce H.

    2010-01-01

    The vast majority of energy necessary for cellular function is produced in mitochondria. Free-radical production and apoptosis are other critical mitochondrial functions. The complex structure, electrochemical properties of the inner mitochondrial membrane (IMM), and genetic control from both mitochondrial DNA (mtDNA) and nuclear DNA (nDNA) are…

  3. [Physicians and the death penalty. Physicians' participation in the death penalty and executions].

    PubMed

    Mertz, J

    1989-06-20

    Doctorss' participation in the death penalty and in executions is described from the literature on the subject. Expert testimonies from psychiatrists during death penalty trials, concerning the mental condition and the possibility of future violent behaviour of the person charged, are of decisive importance for whether the death penalty is imposed or not. By treating prisoners on death row for mental illness the doctor can precipitate the execution. Psychiatrists make fit-for-execution certificates stating whether the condemned is healthy enough to be executed. The doctor monitors the execution and gives advice to the executioner; at an intravenous execution the doctor and medical technique are further involved. It is concluded that doctors should not participate in the death penalty and executions, and that they should discuss ways of achieving such a situation.

  4. Cardioprotection by modulation of mitochondrial respiration during ischemia–reperfusion: Role of apoptosis-inducing factor

    SciTech Connect

    Xu, Aijun; Szczepanek, Karol; Hu, Ying; Lesnefsky, Edward J.; Chen, Qun

    2013-06-14

    Highlights: •Blockade of electron transport prevents the loss of AIF from mitochondria during IR. •Blockade of electron transport decreases caspase-independent cell death during IR. •Mitochondrial AIF content is down-regulated in Harlequin mice. •Blockade of electron transport protects Harlequin mouse hearts during IR. •Amobarbital protection is partially dependent on mitochondrial AIF content. -- Abstract: The transient, reversible blockade of electron transport (BET) during ischemia or at the onset of reperfusion protects mitochondria and decreases cardiac injury. Apoptosis inducing factor (AIF) is located within the mitochondrial intermembrane space. A release of AIF from mitochondria into cytosol and nucleus triggers caspase-independent cell death. We asked if BET prevents the loss of AIF from mitochondria as a mechanism of protection in the buffer perfused heart. BET during ischemia with amobarbital, a rapidly reversible inhibitor of mitochondrial complex I, attenuated a release of AIF from mitochondria into cytosol, in turn decreasing the formation of cleaved and activated PARP-1. These results suggest that BET-mediated protection may occur through prevention of the loss of AIF from mitochondria during ischemia–reperfusion. In order to further clarify the role of mitochondrial AIF in BET-mediated protection, Harlequin (Hq) mice, a genetic model with mitochondrial AIF deficiency, were used to test whether BET could still decrease cell injury in Hq mouse hearts during reperfusion. BET during ischemia protected Hq mouse hearts against ischemia–reperfusion injury and improved mitochondrial function in these hearts during reperfusion. Thus, cardiac injury can still be decreased in the presence of down-regulated mitochondrial AIF content. Taken together, BET during ischemia protects both hearts with normal mitochondrial AIF content and hearts with mitochondrial AIF deficiency. Although preservation of mitochondrial AIF content plays a key role in

  5. Mechanism of neem limonoids-induced cell death in cancer: Role of oxidative phosphorylation.

    PubMed

    Yadav, Neelu; Kumar, Sandeep; Kumar, Rahul; Srivastava, Pragya; Sun, Leimin; Rapali, Peter; Marlowe, Timothy; Schneider, Andrea; Inigo, Joseph R; O'Malley, Jordan; Londonkar, Ramesh; Gogada, Raghu; Chaudhary, Ajay K; Yadava, Nagendra; Chandra, Dhyan

    2016-01-01

    We have previously reported that neem limonoids (neem) induce multiple cancer cell death pathways. Here we dissect the underlying mechanisms of neem-induced apoptotic cell death in cancer. We observed that neem-induced caspase activation does not require Bax/Bak channel-mediated mitochondrial outer membrane permeabilization, permeability transition pore, and mitochondrial fragmentation. Neem enhanced mitochondrial DNA and mitochondrial biomass. While oxidative phosphorylation (OXPHOS) Complex-I activity was decreased, the activities of other OXPHOS complexes including Complex-II and -IV were unaltered. Increased reactive oxygen species (ROS) levels were associated with an increase in mitochondrial biomass and apoptosis upon neem exposure. Complex-I deficiency due to the loss of Ndufa1-encoded MWFE protein inhibited neem-induced caspase activation and apoptosis, but cell death induction was enhanced. Complex II-deficiency due to the loss of succinate dehydrogenase complex subunit C (SDHC) robustly decreased caspase activation, apoptosis, and cell death. Additionally, the ablation of Complexes-I, -III, -IV, and -V together did not inhibit caspase activation. Together, we demonstrate that neem limonoids target OXPHOS system to induce cancer cell death, which does not require upregulation or activation of proapoptotic Bcl-2 family proteins.

  6. Restriction enzyme analysis of the mitochondrial genome in mitochondrial myopathy.

    PubMed Central

    Poulton, J; Turnbull, D M; Mehta, A B; Wilson, J; Gardiner, R M

    1988-01-01

    The mitochondrial myopathies are a heterogeneous group of disorders some of which may be caused by mutations in the mitochondrial genome. Mitochondrial DNA from 10 patients with mitochondrial myopathy and their mothers was analysed using five restriction enzymes and 11 mitochondrial probes in bacteriophage M13. No abnormalities were found in seven out of the 10 patients. Polymorphisms which have not previously been reported were detected in three patients and two of their mothers. These results exclude the presence of deletions or insertions of greater than 60 bp in the region of the mitochondrial genome examined. Any causative mitochondrial DNA mutations in these disorders are therefore likely to be point mutations or small structural rearrangements. Images PMID:2903249

  7. The Armc10/SVH gene: genome context, regulation of mitochondrial dynamics and protection against Aβ-induced mitochondrial fragmentation.

    PubMed

    Serrat, R; Mirra, S; Figueiro-Silva, J; Navas-Pérez, E; Quevedo, M; López-Doménech, G; Podlesniy, P; Ulloa, F; Garcia-Fernàndez, J; Trullas, R; Soriano, E

    2014-04-10

    Mitochondrial function and dynamics are essential for neurotransmission, neural function and neuronal viability. Recently, we showed that the eutherian-specific Armcx gene cluster (Armcx1-6 genes), located in the X chromosome, encodes for a new family of proteins that localise to mitochondria, regulating mitochondrial trafficking. The Armcx gene cluster evolved by retrotransposition of the Armc10 gene mRNA, which is present in all vertebrates and is considered to be the ancestor gene. Here we investigate the genomic organisation, mitochondrial functions and putative neuroprotective role of the Armc10 ancestor gene. The genomic context of the Armc10 locus shows considerable syntenic conservation among vertebrates, and sequence comparisons and CHIP-data suggest the presence of at least three conserved enhancers. We also show that the Armc10 protein localises to mitochondria and that it is highly expressed in the brain. Furthermore, we show that Armc10 levels regulate mitochondrial trafficking in neurons, but not mitochondrial aggregation, by controlling the number of moving mitochondria. We further demonstrate that the Armc10 protein interacts with the KIF5/Miro1-2/Trak2 trafficking complex. Finally, we show that overexpression of Armc10 in neurons prevents Aβ-induced mitochondrial fission and neuronal death. Our data suggest both conserved and differential roles of the Armc10/Armcx gene family in regulating mitochondrial dynamics in neurons, and underscore a protective effect of the Armc10 gene against Aβ-induced toxicity. Overall, our findings support a further degree of regulation of mitochondrial dynamics in the brain of more evolved mammals.

  8. Preventive mitochondrial replacement.

    PubMed

    Orgel, L E

    1997-03-01

    Techniques used recently to clone a sheep generate chimeras with the genome of the donor cell and mainly the mitochondria of the acceptor egg. The use of the same techniques should allow a mother carrying a mitochondrial defect to bear a normal child with normal mitochondria.

  9. Modeling mitochondrial function.

    PubMed

    Balaban, Robert S

    2006-12-01

    The mitochondrion represents a unique opportunity to apply mathematical modeling to a complex biological system. Understanding mitochondrial function and control is important since this organelle is critical in energy metabolism as well as playing key roles in biochemical synthesis, redox control/signaling, and apoptosis. A mathematical model, or hypothesis, provides several useful insights including a rigorous test of the consensus view of the operation of a biological process as well as providing methods of testing and creating new hypotheses. The advantages of the mitochondrial system for applying a mathematical model include the relative simplicity and understanding of the matrix reactions, the ability to study the mitochondria as a independent contained organelle, and, most importantly, one can dynamically measure many of the internal reaction intermediates, on line. The developing ability to internally monitor events within the metabolic network, rather than just the inflow and outflow, is extremely useful in creating critical bounds on complex mathematical models using the individual reaction mechanisms available. However, many serious problems remain in creating a working model of mitochondrial function including the incomplete definition of metabolic pathways, the uncertainty of using in vitro enzyme kinetics, as well as regulatory data in the intact system and the unknown chemical activities of relevant molecules in the matrix. Despite these formidable limitations, the advantages of the mitochondrial system make it one of the best defined mammalian metabolic networks that can be used as a model system for understanding the application and use of mathematical models to study biological systems.

  10. ENERGETICS, EPIGENETICS, MITOCHONDRIAL GENETICS

    PubMed Central

    Wallace, Douglas C.; Fan, Weiwei

    2011-01-01

    The epigenome has been hypothesized to provide the interface between the environment and the nuclear DNA (nDNA) genes. Key factors in the environment are the availability of calories and demands on the organism’s energetic capacity. Energy is funneled through glycolysis and mitochondrial oxidative phosphorylation (OXPHOS), the cellular bioenergetic systems. Since there are thousands of bioenergetic genes dispersed across the chromosomes and mitochondrial DNA (mtDNA), both cis and trans regulation of the nDNA genes is required. The bioenergetic systems convert environmental calories into ATP, acetyl-Coenzyme A (acetyl-CoA), S-adenosyl-methionine (SAM), and reduced NAD+. When calories are abundant, ATP and acetyl-CoA phosphorylate and acetylate chromatin, opening the nDNA for transcription and replication. When calories are limiting, chromatin phosphorylation and acetylation are lost and gene expression is suppressed. DNA methylaton via SAM can also be modulated by mitochondrial function. Phosphorylation and acetylation are also pivotal to regulating cellular signal transduction pathways. Therefore, bioenergetics provides the interface between the environment and the epigenome. Consistent with this conclusion, the clinical phenotypes of bioenergetic diseases are strikingly similar to those observed in epigenetic diseases (Angelman, Rett, Fragile X Syndromes, the laminopathies, cancer, etc.), and an increasing number of epigenetic diseases are being associated with mitochondrial dysfunction. This bioenergetic-epigenomic hypothesis has broad implications for the etiology, pathophysiology, and treatment of a wide range of common diseases. PMID:19796712

  11. Pretreatment Mitochondrial Priming Correlates with Clinical Response to Cytotoxic Chemotherapy

    PubMed Central

    Chonghaile, Triona Ni; Sarosiek, Kristopher A.; Vo, Thanh-Trang; Ryan, Jeremy A.; Tammareddi, Anupama; Moore, Victoria Del Gaizo; Deng, Jing; Anderson, Ken; Richardson, Paul; Tai, Yu-Tzu; Mitsiades, Constantine S.; Matulonis, Ursula A.; Drapkin, Ronny; Stone, Richard; DeAngelo, Daniel J.; McConkey, David J.; Sallan, Stephen E.; Silverman, Lewis; Hirsch, Michelle S.; Carrasco, Daniel Ruben; Letai, Anthony

    2011-01-01

    Cytotoxic chemotherapy targets elements common to all nucleated human cells, such as DNA and microtubules, yet it selectively kills tumor cells. Here we show that clinical response to these drugs correlates with, and may be partially governed by, the pre-treatment proximity of tumor cell mitochondria to the apoptotic threshold, a property called mitochondrial priming. We used BH3 profiling to measure priming in tumor cells from patients with multiple myeloma, acute myelogenous and lymphoblastic leukemia, and ovarian cancer. This assay measures mitochondrial response to peptides derived from pro-apoptotic BH3 domains of proteins critical for death signaling to mitochondria. Patients with highly primed cancers exhibited superior clinical response to chemotherapy. In contrast, chemoresistant cancers and normal tissues were poorly primed. Manipulation of mitochondrial priming might enhance the efficacy of cytotoxic agents. PMID:22033517

  12. Targeting lipid peroxidation and mitochondrial imbalance in Friedreich's ataxia.

    PubMed

    Abeti, Rosella; Uzun, Ebru; Renganathan, Indhushri; Honda, Tadashi; Pook, Mark A; Giunti, Paola

    2015-09-01

    Friedreich's ataxia (FRDA) is an autosomal recessive disorder, caused by reduced levels of the protein frataxin. This protein is located in the mitochondria, where it functions in the biogenesis of iron-sulphur clusters (ISCs), which are important for the function of the mitochondrial respiratory chain complexes. Moreover, disruption in iron biogenesis may lead to oxidative stress. Oxidative stress can be the cause and/or the consequence of mitochondrial energy imbalance, leading to cell death. Fibroblasts from two FRDA mouse models, YG8R and KIKO, were used to analyse two different categories of protective compounds: deuterised poly-unsaturated fatty acids (dPUFAs) and Nrf2-inducers. The former have been shown to protect the cell from damage induced by lipid peroxidation and the latter trigger the well-known Nrf2 antioxidant pathway. Our results show that the sensitivity to oxidative stress of YG8R and KIKO mouse fibroblasts, resulting in cell death and lipid peroxidation, can be prevented by d4-PUFA and Nrf2-inducers (SFN and TBE-31). The mitochondrial membrane potential (ΔΨm) of YG8R and KIKO fibroblasts revealed a difference in their mitochondrial pathophysiology, which may be due to the different genetic basis of the two models. This suggests that variable levels of reduced frataxin may act differently on mitochondrial pathophysiology and that these two cell models could be useful in recapitulating the observed differences in the FRDA phenotype. This may reflect a different modulatory effect towards cell death that will need to be investigated further. PMID:26141703

  13. [The mitochondrial genome of protists].

    PubMed

    Odintsova, M S; Iurina, N P

    2002-06-01

    The data on the structure and functions of the mitochondrial genomes of protists (Protozoa and unicellular red and green algae) are reviewed. It is emphasized that mitochondrial gene structure and composition, as well as organization of mitochondrial genomes in protists are more diverse than in multicellular eukaryotes. The gene content of mitochondrial genomes of protists are closer to those of plants than animals or fungi. In the protist mitochondrial DNA, both the universal (as in higher plants) and modified (as in animals and fungi) genetic codes are used. In the overwhelming majority of cases, protist mitochondrial genomes code for the major and minor rRNA components, some tRNAs, and about 30 proteins of the respiratory chain and ribosomes. Based on comparison of the mitochondrial genomes of various protists, the origin and evolution of mitochondria are briefly discussed.

  14. Silencing of mitochondrial Lon protease deeply impairs mitochondrial proteome and function in colon cancer cells.

    PubMed

    Gibellini, Lara; Pinti, Marcello; Boraldi, Federica; Giorgio, Valentina; Bernardi, Paolo; Bartolomeo, Regina; Nasi, Milena; De Biasi, Sara; Missiroli, Sonia; Carnevale, Gianluca; Losi, Lorena; Tesei, Anna; Pinton, Paolo; Quaglino, Daniela; Cossarizza, Andrea

    2014-12-01

    Lon is a nuclear-encoded, mitochondrial protease that assists protein folding, degrades oxidized/damaged proteins, and participates in maintaining mtDNA levels. Here we show that Lon is up-regulated in several human cancers and that its silencing in RKO colon cancer cells causes profound alterations of mitochondrial proteome and function, and cell death. We silenced Lon in RKO cells by constitutive or inducible expression of Lon shRNA. Lon-silenced cells displayed altered levels of 39 mitochondrial proteins (26% related to stress response, 14.8% to ribosome assembly, 12.7% to oxidative phosphorylation, 8.5% to Krebs cycle, 6.3% to β-oxidation, and 14.7% to crista integrity, ketone body catabolism, and mtDNA maintenance), low levels of mtDNA transcripts, and reduced levels of oxidative phosphorylation complexes (with >90% reduction of complex I). Oxygen consumption rate decreased 7.5-fold in basal conditions, and ATP synthesis dropped from 0.25 ± 0.04 to 0.03 ± 0.001 nmol/mg proteins, in the presence of 2-deoxy-d-glucose. Hydrogen peroxide and mitochondrial superoxide anion levels increased by 3- and 1.3-fold, respectively. Mitochondria appeared fragmented, heterogeneous in size and shape, with dilated cristae, vacuoles, and electrondense inclusions. The triterpenoid 2-cyano-3,12-dioxooleana-1,9,-dien-28-oic acid, a Lon inhibitor, partially mimics Lon silencing. In summary, Lon is essential for maintaining mitochondrial shape and function, and for survival of RKO cells.

  15. Effects of a Sublethal and Transient Stress of the Endoplasmic Reticulum on the Mitochondrial Population.

    PubMed

    Vannuvel, Kayleen; Van Steenbrugge, Martine; Demazy, Catherine; Ninane, Noëlle; Fattaccioli, Antoine; Fransolet, Maude; Renard, Patricia; Raes, Martine; Arnould, Thierry

    2016-09-01

    Endoplasmic reticulum (ER) and mitochondria are not discrete intracellular organelles but establish close physical and functional interactions involved in several biological processes including mitochondrial bioenergetics, calcium homeostasis, lipid synthesis, and the regulation of apoptotic cell death pathways. As many cell types might face a transient and sublethal ER stress during their lifetime, it is thus likely that the adaptive UPR response might affect the mitochondrial population. The aim of this work was to study the putative effects of a non-lethal and transient endoplasmic reticulum stress on the mitochondrial population in HepG2 cells. The results show that thapsigargin and brefeldin A, used to induce a transient and sublethal ER stress, rapidly lead to the fragmentation of the mitochondrial network associated with a decrease in mitochondrial membrane potential, O2 (•-) production and less efficient respiration. These changes in mitochondrial function are transient and preceded by the phosphorylation of JNK. Inhibition of JNK activation by SP600125 prevents the decrease in O2 (•-) production and the mitochondrial network fragmentation observed in cells exposed to the ER stress but has no impact on the reduction of the mitochondrial membrane potential. In conclusion, our data show that a non-lethal and transient ER stress triggers a rapid activation of JNK without inducing apoptosis, leading to the fragmentation of the mitochondrial network and a reduction of O2 (•-) production. J. Cell. Physiol. 231: 1913-1931, 2016. © 2015 Wiley Periodicals, Inc.

  16. Mitochondrial catastrophe during doxorubicin-induced cardiotoxicity: a review of the protective role of melatonin.

    PubMed

    Govender, Jenelle; Loos, Ben; Marais, Erna; Engelbrecht, Anna-Mart

    2014-11-01

    Anthracyclines, such as doxorubicin, are among the most valuable treatments for various cancers, but their clinical use is limited due to detrimental side effects such as cardiotoxicity. Doxorubicin-induced cardiotoxicity is emerging as a critical issue among cancer survivors and is an area of much significance to the field of cardio-oncology. Abnormalities in mitochondrial functions such as defects in the respiratory chain, decreased adenosine triphosphate production, mitochondrial DNA damage, modulation of mitochondrial sirtuin activity and free radical formation have all been suggested as the primary causative factors in the pathogenesis of doxorubicin-induced cardiotoxicity. Melatonin is a potent antioxidant, is nontoxic, and has been shown to influence mitochondrial homeostasis and function. Although a number of studies support the mitochondrial protective role of melatonin, the exact mechanisms by which melatonin confers mitochondrial protection in the context of doxorubicin-induced cardiotoxicity remain to be elucidated. This review focuses on the role of melatonin on doxorubicin-induced bioenergetic failure, free radical generation, and cell death. A further aim is to highlight other mitochondrial parameters such as mitophagy, autophagy, mitochondrial fission and fusion, and mitochondrial sirtuin activity, which lack evidence to support the role of melatonin in the context of cardiotoxicity. PMID:25230823

  17. The mitochondrial Ca2+ uniporter: regulation by auxiliary subunits and signal transduction pathways.

    PubMed

    Jhun, Bong Sook; Mishra, Jyotsna; Monaco, Sarah; Fu, Deming; Jiang, Wenmin; Sheu, Shey-Shing; O-Uchi, Jin

    2016-07-01

    Mitochondrial Ca(2+) homeostasis, the Ca(2+) influx-efflux balance, is responsible for the control of numerous cellular functions, including energy metabolism, generation of reactive oxygen species, spatiotemporal dynamics of Ca(2+) signaling, and cell growth and death. Recent discovery of the molecular identity of the mitochondrial Ca(2+) uniporter (MCU) provides new possibilities for application of genetic approaches to study the mitochondrial Ca(2+) influx mechanism in various cell types and tissues. In addition, the subsequent discovery of various auxiliary subunits associated with MCU suggests that mitochondrial Ca(2+) uptake is not solely regulated by a single protein (MCU), but likely by a macromolecular protein complex, referred to as the MCU-protein complex (mtCUC). Moreover, recent reports have shown the potential role of MCU posttranslational modifications in the regulation of mitochondrial Ca(2+) uptake through mtCUC. These observations indicate that mtCUCs form a local signaling complex at the inner mitochondrial membrane that could significantly regulate mitochondrial Ca(2+) handling, as well as numerous mitochondrial and cellular functions. In this review we discuss the current literature on mitochondrial Ca(2+) uptake mechanisms, with a particular focus on the structure and function of mtCUC, as well as its regulation by signal transduction pathways, highlighting current controversies and discrepancies.

  18. Lipids and cell death in yeast

    PubMed Central

    Eisenberg, Tobias; Büttner, Sabrina

    2014-01-01

    Understanding lipid-induced malfunction represents a major challenge of today's biomedical research. The connection of lipids to cellular and organ dysfunction, cell death, and disease (often referred to as lipotoxicity) is more complex than the sole lipotoxic effects of excess free fatty acids and requires genetically tractable model systems for mechanistic investigation. We herein summarize recent advances in the field of lipid-induced toxicity that employ the established model system for cell death and aging research of budding yeast Saccharomyces cerevisiae. Studies in yeast have shed light on various aspects of lipotoxicity, including free fatty acid toxicity, sphingolipid-modulated cell death as well as the involvement of cardiolipin and lipid peroxidation in the mitochondrial pathways of apoptosis. Regimens used range from exogenously applied lipids, genetic modulation of lipolysis and triacylglyceride synthesis, variations in sphingolipid/ceramide metabolism as well as changes in peroxisome function by either genetic or pharmacological means. In future, the yeast model of programmed cell death will further contribute to the clarification of crucial questions of lipid-associated malfunction. PMID:24119111

  19. A specific isoform of poly(ADP-ribose) glycohydrolase is targeted to the mitochondrial matrix by a N-terminal mitochondrial targeting sequence

    SciTech Connect

    Whatcott, Clifford J.; Meyer-Ficca, Mirella L.; Meyer, Ralph G.; Jacobson, Myron K.

    2009-12-10

    Poly(ADP-ribose) polymerases (PARPs) convert NAD to polymers of ADP-ribose that are converted to free ADP-ribose by poly(ADP-ribose) glycohydrolase (PARG). The activation of the nuclear enzyme PARP-1 following genotoxic stress has been linked to release of apoptosis inducing factor from the mitochondria, but the mechanisms by which signals are transmitted between nuclear and mitochondrial compartments are not well understood. The study reported here has examined the relationship between PARG and mitochondria in HeLa cells. Endogenous PARG associated with the mitochondrial fraction migrated in the range of 60 kDa. Transient transfection of cells with PARG expression constructs with amino acids encoded by exon 4 at the N-terminus was targeted to the mitochondria as demonstrated by subcellular fractionation and immunofluorescence microscopy of whole cells. Deletion and missense mutants allowed identification of a canonical N-terminal mitochondrial targeting sequence consisting of the first 16 amino acids encoded by PARG exon 4. Sub-mitochondrial localization experiments indicate that this mitochondrial PARG isoform is targeted to the mitochondrial matrix. The identification of a PARG isoform as a component of the mitochondrial matrix raises several interesting possibilities concerning mechanisms of nuclear-mitochondrial cross talk involved in regulation of cell death pathways.

  20. Mitochondrial carrier homolog 2 (MTCH2): the recruitment and evolution of a mitochondrial carrier protein to a critical player in apoptosis.

    PubMed

    Robinson, Alan J; Kunji, Edmund R S; Gross, Atan

    2012-07-01

    Recent studies report mitochondrial carrier homolog 2 (MTCH2) as a novel and uncharacterized protein that acts as a receptor-like protein for the truncated BH3-interacting domain death agonist (tBID) protein in the outer membrane of mitochondria. These studies, using mouse embryonic stem cells and fibroblasts as well as mice with a conditional knockout of MTCH2 in the liver, showed that deletion of MTCH2 hindered recruitment of tBID to the mitochondria with subsequent reductions in the activation of pro-apoptotic proteins, mitochondrial outer membrane permeabilization and apoptosis. Sequence analysis shows that MTCH2 is present in all examined multicellular Metazoa as well as unicellular Choanoflagellata, and is a highly derived member of the mitochondrial carrier family. Mitochondrial carriers are monomeric transport proteins that are usually found in the inner mitochondrial membrane, where they exchange small substrates between the mitochondrial matrix and intermembrane space. There are extensive differences between the protein sequences of MTCH2 and other mitochondrial carriers that may explain the ability of MTCH2 to associate with tBID and thus its role in apoptosis. We review the experimental evidence for the role of MTCH2 in apoptosis and suggest that the original transport function of the ancestral MTCH2 mitochondrial carrier has been co-opted by the apoptotic machinery to provide a receptor and signaling mechanism. PMID:22326460

  1. Mitochondrial damage-associated molecular patterns and vascular function†

    PubMed Central

    Wenceslau, Camilla Ferreira; McCarthy, Cameron G.; Szasz, Theodora; Spitler, Kathryn; Goulopoulou, Styliani; Webb, R. Clinton

    2014-01-01

    Immune system activation occurs not only due to foreign stimuli, but also due to endogenous molecules. As such, endogenous molecules that are released into the circulation due to cell death and/or injury alarm the immune system that something has disturbed homeostasis and a response is needed. Collectively, these molecules are known as damage-associated molecular patterns (DAMPs). Mitochondrial DAMPs (mtDAMPs) are potent immunological activators due to the bacterial ancestry of mitochondria. Mitochondrial DAMPs are recognized by specific pattern recognition receptors of the innate immune system, some of which are expressed in the cardiovascular system. Cell death leads to release of mtDAMPs that may induce vascular changes by mechanisms that are currently not well understood. This review will focus on recently published evidence linking mtDAMPs and immune system activation to vascular dysfunction and cardiovascular disease. PMID:24569027

  2. Alzheimer's Proteins, Oxidative Stress, and Mitochondrial Dysfunction Interplay in a Neuronal Model of Alzheimer's Disease

    PubMed Central

    Bobba, Antonella; Petragallo, Vito A.; Marra, Ersilia; Atlante, Anna

    2010-01-01

    In this paper, we discuss the interplay between beta-amyloid (Aβ) peptide, Tau fragments, oxidative stress, and mitochondria in the neuronal model of cerebellar granule neurons (CGNs) in which the molecular events reminiscent of AD are activated. The identification of the death route and the cause/effect relationships between the events leading to death could be helpful to manage the progression of apoptosis in neurodegeneration and to define antiapoptotic treatments acting on precocious steps of the death process. Mitochondrial dysfunction is among the earliest events linked to AD and might play a causative role in disease onset and progression. Recent studies on CGNs have shown that adenine nucleotide translocator (ANT) impairment, due to interaction with toxic N-ter Tau fragment, contributes in a significant manner to bioenergetic failure and mitochondrial dysfunction. These findings open a window for new therapeutic strategies aimed at preserving and/or improving mitochondrial function. PMID:20862336

  3. Mitochondrial Regulatory Pathways in the Pathogenesis of Alzheimer's Disease.

    PubMed

    Adiele, Reginald C; Adiele, Chiedukam A

    2016-07-01

    Alzheimer's disease (AD) is an age-associated neurodegenerative brain disorder with progressive cognitive decline that leads to terminal dementia and death. For decades, amyloid-beta (Aβ) and neurofibrillary tangle (NFT) aggregation hypotheses have dominated studies on the pathogenesis and identification of potential therapeutic targets in AD. Little attention has been paid to the mitochondrial molecular/biochemical pathways leading to AD. Mitochondria play a critical role in cell viability and death including neurons and neuroglia, not only because they regulate energy and oxygen metabolism but also because they regulate cell death pathways. Mitochondrial impairment and oxidative stress are implicated in the pathogenesis of AD. Interestingly, current therapeutics provide symptomatic benefits to AD patients resulting in the use of preventive trials on presymptomatic subjects. This review article elucidates the pathophysiology of AD and emphasizes the need to explore the mitochondrial pathways to provide solutions to unanswered questions in the prevention and treatment of AD. PMID:27392851

  4. The Effects of Death Education.

    ERIC Educational Resources Information Center

    Freitag, Carl B.; Hassler, Shawn David

    Although fear of death is recorded in the writings of the oldest major religions, the study of death and the fear of death have only occurred for the last few decades. Death education courses have grown in number since the early 1970's. College students participated in an investigation of the effects of death education on death anxiety by…

  5. The Carriage of Death: What Kind Does Canada Have?

    PubMed

    Sweatman, Louise R; Sweatman, M Jasmine

    2016-02-01

    Using a carriage of death metaphor, based on Emily Dickinson's poem "Because I Could Not Stop for Death", the authors highlight the development of the last 40 years of the Canadian legal landscape and end-of-life decision making. Beginning with the Canadian Criminal Code, moving through the Rodriguez decision and ending with the recent 2015 Carter decision, they explore how the evolution of time has influenced Canada's highest court. The authors conclude with an exploration of advance care directives and what we may expect as Canada continues its travels down this road. PMID:27169199

  6. Mitochondrial pathway of apoptosis is ancestral in metazoans

    PubMed Central

    Bender, Cheryl E.; Fitzgerald, Patrick; Tait, Stephen W. G.; Llambi, Fabien; McStay, Gavin P.; Tupper, Douglas O.; Pellettieri, Jason; Alvarado, Alejandro Sánchez; Salvesen, Guy S.; Green, Douglas R.

    2012-01-01

    The mitochondrial pathway of apoptosis is the major mechanism of physiological cell death in vertebrates. In this pathway, proapoptotic members of the Bcl-2 family cause mitochondrial outer membrane permeabilization (MOMP), allowing the release of cytochrome c, which interacts with Apaf-1 to trigger caspase activation and apoptosis. Despite conservation of Bcl-2, Apaf-1, and caspases in invertebrate phyla, the existence of the mitochondrial pathway in any invertebrate is, at best, controversial. Here we show that apoptosis in a lophotrochozoan, planaria (phylum Platyhelminthes), is associated with MOMP and that cytochrome c triggers caspase activation in cytosolic extracts from these animals. Further, planarian Bcl-2 family proteins can induce and/or regulate cell death in yeast and can replace Bcl-2 proteins in mammalian cells to regulate MOMP. These results suggest that the mitochondrial pathway of apoptosis in animals predates the emergence of the vertebrates but was lost in some lineages (e.g., nematodes). In further support of this hypothesis, we surveyed the ability of cytochrome c to trigger caspase activation in cytosolic extracts from a variety of organisms and found this effect in cytosolic extracts from invertebrate deuterostomes (phylum Echinodermata). PMID:22416118

  7. Parkinson's disease proteins: Novel mitochondrial targets for cardioprotection

    PubMed Central

    Mukherjee, Uma A.; Ong, Sang-Bing; Ong, Sang-Ging; Hausenloy, Derek J.

    2015-01-01

    Ischemic heart disease (IHD) is the leading cause of death and disability worldwide. Therefore, novel therapeutic targets for protecting the heart against acute ischemia/reperfusion injury (IRI) are required to attenuate cardiomyocyte death, preserve myocardial function, and prevent the onset of heart failure. In this regard, a specific group of mitochondrial proteins, which have been linked to familial forms of Parkinson's disease (PD), may provide novel therapeutic targets for cardioprotection. In dopaminergic neurons of the substantia nigra, these PD proteins, which include Parkin, PINK1, DJ-1, LRRK2, and α-synuclein, play essential roles in preventing cell death—through maintaining normal mitochondrial function, protecting against oxidative stress, mediating mitophagy, and preventing apoptosis. These rare familial forms of PD may therefore provide important insights into the pathophysiology underlying mitochondrial dysfunction and the development of PD. Interestingly, these PD proteins are also present in the heart, but their role in myocardial health and disease is not clear. In this article, we review the role of these PD proteins in the heart and explore their potential as novel mitochondrial targets for cardioprotection. PMID:26481155

  8. Mitochondrial Ca2+ Remodeling is a Prime Factor in Oncogenic Behavior

    PubMed Central

    Rimessi, Alessandro; Patergnani, Simone; Bonora, Massimo; Wieckowski, Mariusz R.; Pinton, Paolo

    2015-01-01

    Cancer is sustained by defects in the mechanisms underlying cell proliferation, mitochondrial metabolism, and cell death. Mitochondrial Ca2+ ions are central to all these processes, serving as signaling molecules with specific spatial localization, magnitude, and temporal characteristics. Mutations in mtDNA, aberrant expression and/or regulation of Ca2+-handling/transport proteins and abnormal Ca2+-dependent relationships among the cytosol, endoplasmic reticulum, and mitochondria can cause the deregulation of mitochondrial Ca2+-dependent pathways that are related to these processes, thus determining oncogenic behavior. In this review, we propose that mitochondrial Ca2+ remodeling plays a pivotal role in shaping the oncogenic signaling cascade, which is a required step for cancer formation and maintenance. We will describe recent studies that highlight the importance of mitochondria in inducing pivotal “cancer hallmarks” and discuss possible tools to manipulate mitochondrial Ca2+ to modulate cancer survival. PMID:26161362

  9. FRIENDLY Regulates Mitochondrial Distribution, Fusion, and Quality Control in Arabidopsis1[W][OPEN

    PubMed Central

    El Zawily, Amr M.; Schwarzländer, Markus; Finkemeier, Iris; Johnston, Iain G.; Benamar, Abdelilah; Cao, Yongguo; Gissot, Clémence; Meyer, Andreas J.; Wilson, Ken; Datla, Raju; Macherel, David; Jones, Nick S.; Logan, David C.

    2014-01-01

    Mitochondria are defining components of most eukaryotes. However, higher plant mitochondria differ biochemically, morphologically, and dynamically from those in other eukaryotes. FRIENDLY, a member of the CLUSTERED MITOCHONDRIA superfamily, is conserved among eukaryotes and is required for correct distribution of mitochondria within the cell. We sought to understand how disruption of FRIENDLY function in Arabidopsis (Arabidopsis thaliana) leads to mitochondrial clustering and the effects of this aberrant chondriome on cell and whole-plant physiology. We present evidence for a role of FRIENDLY in mediating intermitochondrial association, which is a necessary prelude to mitochondrial fusion. We demonstrate that disruption of mitochondrial association, motility, and chondriome structure in friendly affects mitochondrial quality control and leads to mitochondrial stress, cell death, and strong growth phenotypes. PMID:25165398

  10. The Mitochondrial Calcium Uniporter: Mice can live and die without it

    PubMed Central

    Harrington, Josephine L; Murphy, Elizabeth

    2014-01-01

    Calcium is of critical importance to mitochondrial and cell function, and calcium signaling is highly localized in the cell. When stimulated, mitochondria are capable of rapidly taking up calcium, affecting both matrix energetics within mitochondria and shaping the amplitude and frequency of cytosolic calcium “waves”. During pathological conditions a large increase in mitochondrial calcium levels is thought to activate the mitochondrial permeability transition pore, resulting in cell death. The protein responsible for mitochondrial calcium uptake, the mitochondrial calcium uniporter (MCU), was identified in 2011 and its molecular elucidation has stimulated and invigorated research in this area. MCU knockout mice have been created, a variety of other regulators have been identified, and a disease phenotype in humans has been attributed to the loss of a uniporter regulator. In the three years since its molecular elucidation, further research into the MCU has revealed a complex uniporter, and raised many questions about its physiologic and pathologic cell roles. PMID:25451167

  11. Tumor-selective mitochondrial network collapse induced by atmospheric gas plasma-activated medium.

    PubMed

    Saito, Kosuke; Asai, Tomohiko; Fujiwara, Kyoko; Sahara, Junki; Koguchi, Haruhisa; Fukuda, Noboru; Suzuki-Karasaki, Miki; Soma, Masayoshi; Suzuki-Karasaki, Yoshihiro

    2016-04-12

    Non-thermal atmospheric gas plasma (AGP) exhibits cytotoxicity against malignant cells with minimal cytotoxicity toward normal cells. However, the mechanisms of its tumor-selective cytotoxicity remain unclear. Here we report that AGP-activated medium increases caspase-independent cell death and mitochondrial network collapse in a panel of human cancer cells, but not in non-transformed cells. AGP irradiation stimulated reactive oxygen species (ROS) generation in AGP-activated medium, and in turn the resulting stable ROS, most likely hydrogen peroxide (H2O2), activated intracellular ROS generation and mitochondrial ROS (mROS) accumulation. Culture in AGP-activated medium resulted in cell death and excessive mitochondrial fragmentation and clustering, and these responses were inhibited by ROS scavengers. AGP-activated medium also increased dynamin-related protein 1-dependent mitochondrial fission in a tumor-specific manner, and H2O2 administration showed similar effects. Moreover, the vulnerability of tumor cells to mitochondrial network collapse appeared to result from their higher sensitivity to mROS accumulation induced by AGP-activated medium or H2O2. The present findings expand our previous observations on death receptor-mediated tumor-selective cell killing and reinforce the importance of mitochondrial network remodeling as a powerful target for tumor-selective cancer treatment.

  12. Programmed cell death in aging

    PubMed Central

    Tower, John

    2015-01-01

    Programmed cell death (PCD) pathways, including apoptosis and regulated necrosis, are required for normal cell turnover and tissue homeostasis. Mis-regulation of PCD is increasingly implicated in aging and aging-related disease. During aging the cell turnover rate declines for several highly-mitotic tissues. Aging-associated disruptions in systemic and inter-cell signaling combined with cell-autonomous damage and mitochondrial malfunction result in increased PCD in some cell types, and decreased PCD in other cell types. Increased PCD during aging is implicated in immune system decline, skeletal muscle wasting (sarcopenia), loss of cells in the heart, and neurodegenerative disease. In contrast, cancer cells and senescent cells are resistant to PCD, enabling them to increase in abundance during aging. PCD pathways limit life span in fungi, but whether PCD pathways normally limit adult metazoan life span is not yet clear. PCD is regulated by a balance of negative and positive factors, including the mitochondria, which are particularly subject to aging-associated malfunction. PMID:25862945

  13. Targeting Mitochondria with Avocatin B Induces Selective Leukemia Cell Death.

    PubMed

    Lee, Eric A; Angka, Leonard; Rota, Sarah-Grace; Hanlon, Thomas; Mitchell, Andrew; Hurren, Rose; Wang, Xiao Ming; Gronda, Marcela; Boyaci, Ezel; Bojko, Barbara; Minden, Mark; Sriskanthadevan, Shrivani; Datti, Alessandro; Wrana, Jeffery L; Edginton, Andrea; Pawliszyn, Janusz; Joseph, Jamie W; Quadrilatero, Joe; Schimmer, Aaron D; Spagnuolo, Paul A

    2015-06-15

    Treatment regimens for acute myeloid leukemia (AML) continue to offer weak clinical outcomes. Through a high-throughput cell-based screen, we identified avocatin B, a lipid derived from avocado fruit, as a novel compound with cytotoxic activity in AML. Avocatin B reduced human primary AML cell viability without effect on normal peripheral blood stem cells. Functional stem cell assays demonstrated selectivity toward AML progenitor and stem cells without effects on normal hematopoietic stem cells. Mechanistic investigations indicated that cytotoxicity relied on mitochondrial localization, as cells lacking functional mitochondria or CPT1, the enzyme that facilitates mitochondria lipid transport, were insensitive to avocatin B. Furthermore, avocatin B inhibited fatty acid oxidation and decreased NADPH levels, resulting in ROS-dependent leukemia cell death characterized by the release of mitochondrial proteins, apoptosis-inducing factor, and cytochrome c. This study reveals a novel strategy for selective leukemia cell eradication based on a specific difference in mitochondrial function. PMID:26077472

  14. Physiological and pathological roles of the mitochondrial permeability transition pore in the heart

    PubMed Central

    Kwong, Jennifer Q; Molkentin, Jeffery D

    2015-01-01

    Summary Prolonged mitochondrial permeability transition pore (MPTP) opening results in mitochondrial energetic dysfunction, organelle swelling, rupture and typically a type of necrotic cell death. However, acute opening of the MPTP has a critical physiologic role in regulating mitochondrial Ca2+ handling and metabolism. Despite the physiological and pathological roles that the MPTP orchestrates, the proteins that comprise the pore itself remain an area of ongoing investigation. Here, we will discuss the molecular composition of the MPTP and its role in regulating cardiac physiology and disease. A better understanding of MPTP structure and function will likely suggest novel cardioprotective therapeutic approaches. PMID:25651175

  15. Abnormal Mitochondrial L-Arginine Transport Contributes to the Pathogenesis of Heart Failure and Rexoygenation Injury

    PubMed Central

    Byrne, Melissa; Joshi, Mandar; Horlock, Duncan; Lam, Nicholas T.; Gregorevic, Paul; McGee, Sean L.; Kaye, David M.

    2014-01-01

    Background Impaired mitochondrial function is fundamental feature of heart failure (HF) and myocardial ischemia. In addition to the effects of heightened oxidative stress, altered nitric oxide (NO) metabolism, generated by a mitochondrial NO synthase, has also been proposed to impact upon mitochondrial function. However, the mechanism responsible for arginine transport into mitochondria and the effect of HF on such a process is unknown. We therefore aimed to characterize mitochondrial L-arginine transport and to investigate the hypothesis that impaired mitochondrial L-arginine transport plays a key role in the pathogenesis of heart failure and myocardial injury. Methods and Results In mitochondria isolated from failing hearts (sheep rapid pacing model and mouse Mst1 transgenic model) we demonstrated a marked reduction in L-arginine uptake (p<0.05 and p<0.01 respectively) and expression of the principal L-arginine transporter, CAT-1 (p<0.001, p<0.01) compared to controls. This was accompanied by significantly lower NO production and higher 3-nitrotyrosine levels (both p<0.05). The role of mitochondrial L-arginine transport in modulating cardiac stress responses was examined in cardiomyocytes with mitochondrial specific overexpression of CAT-1 (mtCAT1) exposed to hypoxia-reoxygenation stress. mtCAT1 cardiomyocytes had significantly improved mitochondrial membrane potential, respiration and ATP turnover together with significantly decreased reactive oxygen species production and cell death following mitochondrial stress. Conclusion These data provide new insights into the role of L-arginine transport in mitochondrial biology and cardiovascular disease. Augmentation of mitochondrial L-arginine availability may be a novel therapeutic strategy for myocardial disorders involving mitochondrial stress such as heart failure and reperfusion injury. PMID:25111602

  16. Widespread mitochondrial depletion via mitophagy does not compromise necroptosis

    PubMed Central

    Tait, Stephen W.G.; Oberst, Andrew; Quarato, Giovanni; Milasta, Sandra; Haller, Martina; Wang, Ruoning; Karvela, Maria; Ichim, Gabriel; Yatim, Nader; Albert, Matthew L.; Kidd, Grahame; Wakefield, Randall; Frase, Sharon; Krautwald, Stefan; Linkermann, Andreas; Green, Douglas R.

    2014-01-01

    Summary Programmed necrosis (or necroptosis) is a form of cell death triggered by the activation of receptor interacting protein kinase-3 (RIPK3). Several reports have implicated mitochondria and mitochondrial reactive oxygen species (ROS) generation as effectors of RIPK3-dependent cell death. Here, we directly test this idea by employing a method for the specific removal of mitochondria via mitophagy. Mitochondria-deficient cells were resistant to the mitochondrial pathway of apoptosis, but efficiently died via TNF-induced, RIPK3-dependent programmed necrosis or as a result of direct oligomerization of RIPK3. Although the ROS scavenger butylated hydroxyanisol (BHA) delayed TNF-induced necroptosis, it had no effect on necroptosis induced by RIPK3 oligomerization. Further, while TNF-induced ROS production was dependent on mitochondria, the inhibition of TNF-induced necroptosis by BHA was observed in mitochondria-depleted cells. Our data indicate that mitochondrial ROS production accompanies, but does not cause, RIPK3-dependent necroptotic cell death. PMID:24268776

  17. Widespread mitochondrial depletion via mitophagy does not compromise necroptosis.

    PubMed

    Tait, Stephen W G; Oberst, Andrew; Quarato, Giovanni; Milasta, Sandra; Haller, Martina; Wang, Ruoning; Karvela, Maria; Ichim, Gabriel; Yatim, Nader; Albert, Matthew L; Kidd, Grahame; Wakefield, Randall; Frase, Sharon; Krautwald, Stefan; Linkermann, Andreas; Green, Douglas R

    2013-11-27

    Programmed necrosis (or necroptosis) is a form of cell death triggered by the activation of receptor interacting protein kinase-3 (RIPK3). Several reports have implicated mitochondria and mitochondrial reactive oxygen species (ROS) generation as effectors of RIPK3-dependent cell death. Here, we directly test this idea by employing a method for the specific removal of mitochondria via mitophagy. Mitochondria-deficient cells were resistant to the mitochondrial pathway of apoptosis, but efficiently died via tumor necrosis factor (TNF)-induced, RIPK3-dependent programmed necrosis or as a result of direct oligomerization of RIPK3. Although the ROS scavenger butylated hydroxyanisole (BHA) delayed TNF-induced necroptosis, it had no effect on necroptosis induced by RIPK3 oligomerization. Furthermore, although TNF-induced ROS production was dependent on mitochondria, the inhibition of TNF-induced necroptosis by BHA was observed in mitochondria-depleted cells. Our data indicate that mitochondrial ROS production accompanies, but does not cause, RIPK3-dependent necroptotic cell death. PMID:24268776

  18. The development of mitochondrial medicine.

    PubMed Central

    Luft, R

    1994-01-01

    Primary defects in mitochondrial function are implicated in over 100 diseases, and the list continues to grow. Yet the first mitochondrial defect--a myopathy--was demonstrated only 35 years ago. The field's dramatic expansion reflects growth of knowledge in three areas: (i) characterization of mitochondrial structure and function, (ii) elucidation of the steps involved in mitochondrial biosynthesis, and (iii) discovery of specific mitochondrial DNA. Many mitochondrial diseases are accompanied by mutations in this DNA. Inheritance is by maternal transmission. The metabolic defects encompass the electron transport complexes, intermediates of the tricarboxylic acid cycle, and substrate transport. The clinical manifestations are protean, most often involving skeletal muscle and the central nervous system. In addition to being a primary cause of disease, mitochondrial DNA mutations and impaired oxidation have now been found to occur as secondary phenomena in aging as well as in age-related degenerative diseases such as Parkinson, Alzheimer, and Huntington diseases, amyotrophic lateral sclerosis and cardiomyopathies, atherosclerosis, and diabetes mellitus. Manifestations of both the primary and secondary mitochondrial diseases are thought to result from the production of oxygen free radicals. With increased understanding of the mechanisms underlying the mitochondrial dysfunctions has come the beginnings of therapeutic strategies, based mostly on the administration of antioxidants, replacement of cofactors, and provision of nutrients. At the present accelerating pace of development of what may be called mitochondrial medicine, much more is likely to be achieved within the next few years. Images PMID:8090715

  19. Mitochondria, calcium and cell death: A deadly triad in neurodegeneration

    PubMed Central

    Celsi, Fulvio; Pizzo, Paola; Brini, Marisa; Leo, Sara; Fotino, Carmen; Pinton, Paolo; Rizzuto, Rosario

    2009-01-01

    Mitochondrial Ca2+ accumulation is a tightly controlled process, in turn regulating functions as diverse as aerobic metabolism and induction of cell death. The link between Ca2+ (dys)regulation, mitochondria and cellular derangement is particularly evident in neurodegenerative disorders, in which genetic models and environmental factors allowed to identify common traits in the pathogenic routes. We will here summarize: i) the current view of mechanisms and functions of mitochondrial Ca2+ homeostasis, ii) the basic principles of organelle Ca2+ transport, iii) the role of Ca2+ in neuronal cell death, and iv) the new information on the pathogenesis of Alzheimer's, Huntington's and Parkinson's diseases, highlighting the role of Ca2+ and mitochondria. PMID:19268425

  20. Brain Death and Islam

    PubMed Central

    Ziad-Miller, Amna; Elamin, Elamin M.

    2014-01-01

    How one defines death may vary. It is important for clinicians to recognize those aspects of a patient’s religious beliefs that may directly influence medical care and how such practices may interface with local laws governing the determination of death. Debate continues about the validity and certainty of brain death criteria within Islamic traditions. A search of PubMed, Scopus, EMBASE, Web of Science, PsycNet, Sociological Abstracts, DIALOGUE ProQuest, Lexus Nexus, Google, and applicable religious texts was conducted to address the question of whether brain death is accepted as true death among Islamic scholars and clinicians and to discuss how divergent opinions may affect clinical care. The results of the literature review inform this discussion. Brain death has been acknowledged as representing true death by many Muslim scholars and medical organizations, including the Islamic Fiqh Academies of the Organization of the Islamic Conference and the Muslim World League, the Islamic Medical Association of North America, and other faith-based medical organizations as well as legal rulings by multiple Islamic nations. However, consensus in the Muslim world is not unanimous, and a sizable minority accepts death by cardiopulmonary criteria only. PMID:25287999

  1. Conflicting Thoughts about Death

    ERIC Educational Resources Information Center

    Harris, Paul L.

    2011-01-01

    Most research on children's conception of death has probed their understanding of its biological aspects: its inevitability, irreversibility and terminal impact. Yet many adults subscribe to a religious conception implying that death marks the beginning of a new life. Two recent empirical studies confirm that in the course of development, children…

  2. Death Acceptance through Ritual

    ERIC Educational Resources Information Center

    Reeves, Nancy C.

    2011-01-01

    This article summarizes the author's original research, which sought to discover the elements necessary for using death-related ritual as a psychotherapeutic technique for grieving people who experience their grief as "stuck," "unending," "maladaptive," and so on. A "death-related ritual" is defined as a ceremony, directly involving at least 1…

  3. Near-death experiences.

    PubMed

    Blackmore, S J

    1996-02-01

    Reactions to claims of near-death experiences (NDE) range from the popular view that this must be evidence for life after death, to outright rejection of the experiences as, at best, drug induced hallucinations or, at worse, pure invention. Twenty years, and much research, later, it is clear that neither extreme is correct.

  4. The Psychology of Death

    ERIC Educational Resources Information Center

    Fields, B. Celestine

    1976-01-01

    Forty-eight black men and women living and/or attending school in the St. Louis and Washington, D.C. areas responded to questionnaires concerning feelings, attitudes, emotions, etc. towards death and dying. It is concluded that blacks see death as a very significant happening; and that although in some areas blacks have become Americanized in…

  5. Death Writ Large

    ERIC Educational Resources Information Center

    Kastenbaum, Robert

    2004-01-01

    Mainstream thanatology has devoted its efforts to improving the understanding, care, and social integration of people who are confronted with life-threatening illness or bereavement. This article suggests that it might now be time to expand the scope and mission to include large-scale death and death that occurs through complex and multi-domain…

  6. Near-death experiences.

    PubMed Central

    Blackmore, S J

    1996-01-01

    Reactions to claims of near-death experiences (NDE) range from the popular view that this must be evidence for life after death, to outright rejection of the experiences as, at best, drug induced hallucinations or, at worse, pure invention. Twenty years, and much research, later, it is clear that neither extreme is correct. PMID:8683504

  7. Mozart's illnesses and death.

    PubMed Central

    Davies, P J

    1983-01-01

    Throughout his life Mozart suffered frequent attacks of tonsillitis. In 1784 he developed post-streptococcal Schönlein-Henoch syndrome which caused chronic glomerular nephritis and chronic renal failure. His fatal illness was due to Schönlein-Henoch purpura, with death from cerebral haemorrhage and bronchopneumonia. Venesection(s) may have contributed to his death. PMID:6352940

  8. Reflections on Death Education

    ERIC Educational Resources Information Center

    Riskey, Raymond J.

    1977-01-01

    The author comments on the need to discuss death openly in the classroom, noting that engaging students with the idea of coming to grips with the fact of their own death can prepare them for living, working, and loving more fully. (SH)

  9. SUICIDE ON DEATH ROW.

    PubMed

    Tartaro, Christine; Lester, David

    2015-12-01

    For the period 1976-2011, the suicide rate on death rows in the United States was only weakly (and non-significantly) associated with the marriage, birth, divorce, and unemployment rates in the general population. Possible explanations for why social indicators in the larger society might be associated with the behavior of prisoners on death row were discussed. PMID:26595302

  10. The Sociology of Death

    ERIC Educational Resources Information Center

    Fulton, Robert

    1977-01-01

    When we start to look at the issues associated with dying and death, we must do so in terms of the broadest parameters imaginable. Presented at the Conference on Death and Dying: Education, Counseling, and Care, December 1-3, 1976, Orlando, Florida. (Author)

  11. Programmed cell death

    SciTech Connect

    1995-12-31

    The purpose of this conference to provide a multidisciplinary forum for exchange of state-of-the-art information on the role programmed cell death plays in normal development and homeostasis of many organisms. This volume contains abstracts of papers in the following areas: invertebrate development; immunology/neurology; bcl-2 family; biochemistry; programmed cell death in viruses; oncogenesis; vertebrate development; and diseases.

  12. Natural death while driving.

    PubMed

    Oström, M; Eriksson, A

    1987-07-01

    Of sudden natural deaths while driving, 126 occurred during 1980 through 1985 in the northern half of Sweden. The mean age of the 69 car driver victims was 59 years, considerably higher than that of traumatic car deaths, and all but 2 were males. The mean age of 57 operators of other vehicles was 66 years, and of these, 6 were women. Seven car drivers were stricken during commercial employment. Most accidents occurred during daytime and the distribution of the weekdays was fairly even. Ischemic heart disease accounted for 112 deaths, and other cardiovascular diseases for an additional 9 deaths. Only 1/5 of the victims experienced previous symptoms of disease. Out of at least 31 other persons at risk in the car deaths, only 2 passengers suffered minor injuries. The trauma in the deceased was in most cases minor in both car and other vehicle deaths. Property damage was also minimal. At least 1/3 of the drivers were able to stop the car before becoming unconscious. In none of the car cases was alcohol detected in the blood, while alcohol was identified in at least 2 of the other vehicle victims. The findings here agree with previous studies that natural deaths at the wheel are fairly uncommon, and that the risk for other persons is not significant. The value of adequate postmortem examinations of drivers dying in traffic is stressed--natural deaths can otherwise be overlooked. PMID:3612079

  13. Death Obsession in Palestinians

    ERIC Educational Resources Information Center

    Abdel-Khalek, Ahmed M.; Al-Arja, Nahida S.; Abdalla, Taysir

    2006-01-01

    The authors explored death obsession level and correlates among a sample (N=601) of Palestinians living in the city of Beit Jala, the village of Al-Khader, and the Aida refugee camp in the Bethlehem area. They live in war conditions; the houses of half of them have been demolished. The Death Obsession Scale (DOS) was administered. Its alpha…

  14. The mitochondrial permeability transition pore in AD 2016: An update.

    PubMed

    Biasutto, Lucia; Azzolini, Michele; Szabò, Ildikò; Zoratti, Mario

    2016-10-01

    Over the past 30years the mitochondrial permeability transition - the permeabilization of the inner mitochondrial membrane due to the opening of a wide pore - has progressed from being considered a curious artifact induced in isolated mitochondria by Ca(2+) and phosphate to a key cell-death-inducing process in several major pathologies. Its relevance is by now universally acknowledged and a pharmacology targeting the phenomenon is being developed. The molecular nature of the pore remains to this day uncertain, but progress has recently been made with the identification of the FOF1 ATP synthase as the probable proteic substrate. Researchers sharing this conviction are however divided into two camps: these believing that only the ATP synthase dimers or oligomers can form the pore, presumably in the contact region between monomers, and those who consider that the ring-forming c subunits in the FO sector actually constitute the walls of the pore. The latest development is the emergence of a new candidate: Spastic Paraplegia 7 (SPG7), a mitochondrial AAA-type membrane protease which forms a 6-stave barrel. This review summarizes recent developments of research on the pathophysiological relevance and on the molecular nature of the mitochondrial permeability transition pore. This article is part of a Special Issue entitled: Mitochondrial Channels edited by Pierre Sonveaux, Pierre Maechler and Jean-Claude Martinou. PMID:26902508

  15. The mitochondrial permeability transition pore in AD 2016: An update.

    PubMed

    Biasutto, Lucia; Azzolini, Michele; Szabò, Ildikò; Zoratti, Mario

    2016-10-01

    Over the past 30years the mitochondrial permeability transition - the permeabilization of the inner mitochondrial membrane due to the opening of a wide pore - has progressed from being considered a curious artifact induced in isolated mitochondria by Ca(2+) and phosphate to a key cell-death-inducing process in several major pathologies. Its relevance is by now universally acknowledged and a pharmacology targeting the phenomenon is being developed. The molecular nature of the pore remains to this day uncertain, but progress has recently been made with the identification of the FOF1 ATP synthase as the probable proteic substrate. Researchers sharing this conviction are however divided into two camps: these believing that only the ATP synthase dimers or oligomers can form the pore, presumably in the contact region between monomers, and those who consider that the ring-forming c subunits in the FO sector actually constitute the walls of the pore. The latest development is the emergence of a new candidate: Spastic Paraplegia 7 (SPG7), a mitochondrial AAA-type membrane protease which forms a 6-stave barrel. This review summarizes recent developments of research on the pathophysiological relevance and on the molecular nature of the mitochondrial permeability transition pore. This article is part of a Special Issue entitled: Mitochondrial Channels edited by Pierre Sonveaux, Pierre Maechler and Jean-Claude Martinou.

  16. Platyzoan mitochondrial genomes.

    PubMed

    Wey-Fabrizius, Alexandra R; Podsiadlowski, Lars; Herlyn, Holger; Hankeln, Thomas

    2013-11-01

    Platyzoa is a putative lophotrochozoan (spiralian) subtaxon within the protostome clade of Metazoa, comprising a range of biologically diverse, mostly small worm-shaped animals. The monophyly of Platyzoa, the relationships between the putative subgroups Platyhelminthes, Gastrotricha and Gnathifera (the latter comprising at least Gnathostomulida, "Rotifera" and Acanthocephala) as well as some aspects of the internal phylogenies of these subgroups are highly debated. Here we review how complete mitochondrial (mt) genome data contribute to these debates. We highlight special features of the mt genomes and discuss problems in mtDNA phylogenies of the clade. Mitochondrial genome data seem to be insufficient to resolve the position of the platyzoan clade within the Spiralia but can help to address internal phylogenetic questions. The present review includes a tabular survey of all published platyzoan mt genomes. PMID:23274056

  17. Platyzoan mitochondrial genomes.

    PubMed

    Wey-Fabrizius, Alexandra R; Podsiadlowski, Lars; Herlyn, Holger; Hankeln, Thomas

    2013-11-01

    Platyzoa is a putative lophotrochozoan (spiralian) subtaxon within the protostome clade of Metazoa, comprising a range of biologically diverse, mostly small worm-shaped animals. The monophyly of Platyzoa, the relationships between the putative subgroups Platyhelminthes, Gastrotricha and Gnathifera (the latter comprising at least Gnathostomulida, "Rotifera" and Acanthocephala) as well as some aspects of the internal phylogenies of these subgroups are highly debated. Here we review how complete mitochondrial (mt) genome data contribute to these debates. We highlight special features of the mt genomes and discuss problems in mtDNA phylogenies of the clade. Mitochondrial genome data seem to be insufficient to resolve the position of the platyzoan clade within the Spiralia but can help to address internal phylogenetic questions. The present review includes a tabular survey of all published platyzoan mt genomes.

  18. Death in Denmark.

    PubMed Central

    Evans, M

    1990-01-01

    Does it matter that the hearts of 'brainstem dead' patients may persist in beating spontaneously? Hostile reactions, to the Danish inclusion of cardiac criteria in the determination of death, betray reductionist views of human life at the core of 'brainstem' conceptions of death. Such views (whether centred on neurological function or on abstractions concerning 'personhood') supplant the richness of human life and death with the poverty of essentialism: and mask the lethal nature of beating-heart organ retrieval. The affirmation of cardiac criteria for death is not an alternative form of essentialism as some critics suppose, but part of an understanding of human life and death which rejects essentialism altogether. The spontaneously persistent heartbeat does not constitute human life, but most certainly counts for it. PMID:2287015

  19. Death in Denmark.

    PubMed

    Evans, M

    1990-12-01

    Does it matter that the hearts of 'brainstem dead' patients may persist in beating spontaneously? Hostile reactions, to the Danish inclusion of cardiac criteria in the determination of death, betray reductionist views of human life at the core of 'brainstem' conceptions of death. Such views (whether centred on neurological function or on abstractions concerning 'personhood') supplant the richness of human life and death with the poverty of essentialism: and mask the lethal nature of beating-heart organ retrieval. The affirmation of cardiac criteria for death is not an alternative form of essentialism as some critics suppose, but part of an understanding of human life and death which rejects essentialism altogether. The spontaneously persistent heartbeat does not constitute human life, but most certainly counts for it.

  20. Mitochondrial Genetic Variation in Iranian Infertile Men with Varicocele

    PubMed Central

    Heidari, Mohammad Mehdi; Khatami, Mehri; Danafar, Amirhossein; Dianat, Tahere; Farahmand, Ghazaleh; Talebi, Ali Reza

    2016-01-01

    Background: Several recent studies have shown that mitochondrial DNA mutations lead to major disabilities and premature death in carriers. More than 150 mutations in human mitochondrial DNA (mtDNA) genes have been associated with a wide spectrum of disorders. Varicocele, one of the causes of infertility in men wherein abnormal inflexion and distension of veins of the pampiniform plexus is observed within spermatic cord, can increase reactive oxygen species (ROS) production in semen and cause oxidative stress and sperm dysfunction in patients. Given that mitochondria are the source of ROS production in cells, the aim of this study was to scan nine mitochondrial genes (MT-COX2, MT-tRNALys , MT-ATP8, MT-ATP6, MT-COX3, MT-tRNAGly , MT-ND3, MT-tRNAArg and MT-ND4L) for mutations in infertile patients with varicocele. Materials and Methods: In this cross-sectional study, polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) and DNA sequencing were used to detect and identify point mutations respectively in 9 mitochondrial genes in 72 infertile men with varicocele and 159 fertile men. In brief, the samples showing altered electrophoretic patterns of DNA in the SSCP gel were sent for DNA sequencing to identify the exact nucleotide variation. Results: Ten type nucleotide variants were detected exclusively in mitochondrial DNA of infertile men. These include six novel nucleotide changes and four variants previously reported for other disorders. Conclusion: Mutations in mitochondrial genes may affect respiratory complexes in combination with environmental risk factors. Therefore these nucleotide variants probably lead to impaired ATP synthesis and mitochondrial function ultimately interfering with sperm motility and infertility. PMID:27695613

  1. Antioxidant treatment reverses mitochondrial dysfunction in a sepsis animal model.

    PubMed

    Zapelini, Paula H; Rezin, Gislaine T; Cardoso, Mariane R; Ritter, Cristiane; Klamt, Fábio; Moreira, José C F; Streck, Emilio L; Dal-Pizzol, Felipe

    2008-06-01

    Evidence from the literature has demonstrated that reactive oxygen species (ROS) play an important role in the development of multiple organ failure and septic shock. In addition, mitochondrial dysfunction has been implicated in the pathogenesis of multiple organ dysfunction syndrome (MODS). The hypothesis of cytopathic hypoxia postulates that impairment in mitochondrial oxidative phosphorylation reduces aerobic adenosine triphosphate (ATP) production and potentially induces MODS. In this work, our aim was to evaluate the effects of antioxidants on oxidative damage and energy metabolism parameters in liver of rats submitted to a cecal ligation puncture (CLP) model of sepsis. We speculate that CLP induces a sequence of events that culminate with liver cells death. We propose that mitochondrial superoxide production induces mitochondrial oxidative damage, leading to mitochondrial dysfunction, swelling and release of cytochrome c. These events occur in early sepsis development, as reported in the present work. Liver cells necrosis only occurs 24 h after CLP, but all other events occur earlier (6-12 h). Moreover, we showed that antioxidants may prevent oxidative damage and mitochondrial dysfunction in liver of rats after CLP. In another set of experiments, we verified that L-NAME administration did not reverse increase of superoxide anion production, TBARS formation, protein carbonylation, mitochondrial swelling, increased serum AST or inhibition on complex IV activity caused by CLP. Considering that this drug inhibits nitric oxide synthase and that no parameter was reversed by its administration, we suggest that all the events reported in this study are not mediated by nitric oxide. In conclusion, although it is difficult to extrapolate our findings to human, it is tempting to speculate that antioxidants may be used in the future in the treatment of this disease. PMID:18417427

  2. Cell death induced by the Alternaria mycotoxin Alternariol.

    PubMed

    Bensassi, Fatma; Gallerne, Cindy; Sharaf El Dein, Ossama; Hajlaoui, Mohamed Rabeh; Bacha, Hassen; Lemaire, Christophe

    2012-09-01

    Mycotoxins are unavoidable contaminants of most foods and feeds, and some are known to be detrimental to human health. It is thus worthwhile to understand how cells of the intestinal system, one of the primary targets of these toxins, respond to their toxic effects. In this study, human colon carcinoma cells were used to elucidate the cell death mode and the pathways triggered by Alternariol (AOH), the most important mycotoxin produced by Alternaria species, which are the most common mycoflora infecting small grain cereals worldwide. Treatment of cells with AOH resulted in a loss of cell viability by inducing apoptosis. AOH-induced apoptosis was mediated through a mitochondria-dependent pathway, characterized by a p53 activation, an opening of the mitochondrial permeability transition pore (PTP), a loss of mitochondrial transmembrane potential (ΔΨm), a downstream generation of O(2)(*-) and caspase 9 and 3 activation. Besides, deficiency of the pro-apoptotic protein Bax partially protected cells against AOH-induced mitochondrial alterations. In addition, experiments performed on purified mitochondria indicated that AOH does not directly target this organelle to induce cell death. Our results demonstrate for the first time that AOH-induced cytotoxicity is mediated by activation of the mitochondrial pathway of apoptosis in human colon carcinoma cells.

  3. Endosymbionts and mitochondrial origins

    NASA Technical Reports Server (NTRS)

    Woese, C. R.

    1977-01-01

    The possibility is put forth that the mitochondrion did not originate from an endosymbiosis 1-2 billion years ago involving an aerobic bacterium. Rather, it arose by endosymbiosis in a much earlier anaerobic period and was initially a photosynthetic organelle analogous to the modern chloroplast. This suggestion arises from a reconsideration of the nature of endosymbiosis. It explains the remarkable diversity in mitochondrial information storage and processing systems.

  4. Human Mitochondrial DNA Replication

    PubMed Central

    Holt, Ian J.; Reyes, Aurelio

    2012-01-01

    Elucidation of the process of DNA replication in mitochondria is in its infancy. For many years, maintenance of the mitochondrial genome was regarded as greatly simplified compared to the nucleus. Mammalian mitochondria were reported to lack all DNA repair systems, to eschew DNA recombination, and to possess but a single DNA polymerase, polymerase γ. Polγ was said to replicate mitochondrial DNA exclusively via one mechanism, involving only two priming events and a handful of proteins. In this “strand-displacement model,” leading strand DNA synthesis begins at a specific site and advances approximately two-thirds of the way around the molecule before DNA synthesis is initiated on the “lagging” strand. Although the displaced strand was long-held to be coated with protein, RNA has more recently been proposed in its place. Furthermore, mitochondrial DNA molecules with all the features of products of conventional bidirectional replication have been documented, suggesting that the process and regulation of replication in mitochondria is complex, as befits a genome that is a core factor in human health and longevity. PMID:23143808

  5. Leishmania donovani: intracellular ATP level regulates apoptosis-like death in luteolin induced dyskinetoplastid cells.

    PubMed

    Sen, Nilkantha; Das, Benu Brata; Ganguly, Agneyo; Banerjee, Bijoylaxhmi; Sen, Tanusree; Majumder, Hemanta K

    2006-11-01

    Leishmaniasis presents a spectrum of diseases ranging from benign cutaneous lesions to the often-fatal visceralizing form. Luteolin, a dietary flavone induces apoptosis-like death in both promastigote and amastigote forms of Leishmania, the causative agent of the diseases. Here, we have elucidated the mechanism of action of luteolin by analyzing the mitochondrial and cytosolic changes associated with apoptosis-like death of leishmanial cells. In Leishmania donovani, treatment with luteolin induces the loss of both maxicircles and minicircles which resulted in the formation of dyskinetoplastid cells. The loss of mitochondrial DNA causes reduction in the activities of complex I, II, III, and IV of electron transport chain. However, the mitochondrial ATPase activity of complex V remains almost unaltered during treatment with luteolin but the sensitivity to oligomycin is lost. The inactivation of ETC complex is associated with decrease in mitochondrial as well as glycolytic ATP production, which is responsible for depolarization of Deltapsi(m) and alteration in mitochondrial structure. This event is followed by the release of cytochrome c from mitochondria in mt-DNA depleted leishmanial cells and causes an activation of caspase like proteases. Collectively our results provide the first insight into the mechanistic pathway of apoptosis-like death where inhibition of glycolytic ATP production is an essential event responsible for depolarization of Deltapsi(m) in mt-DNA depleted cells to propagate apoptosis-like death in leishmanial cells. PMID:16707127

  6. SET overexpression in HEK293 cells regulates mitochondrial uncoupling proteins levels within a mitochondrial fission/reduced autophagic flux scenario.

    PubMed

    Almeida, Luciana O; Goto, Renata N; Neto, Marinaldo P C; Sousa, Lucas O; Curti, Carlos; Leopoldino, Andréia M

    2015-03-01

    We hypothesized that SET, a protein accumulated in some cancer types and Alzheimer disease, is involved in cell death through mitochondrial mechanisms. We addressed the mRNA and protein levels of the mitochondrial uncoupling proteins UCP1, UCP2 and UCP3 (S and L isoforms) by quantitative real-time PCR and immunofluorescence as well as other mitochondrial involvements, in HEK293 cells overexpressing the SET protein (HEK293/SET), either in the presence or absence of oxidative stress induced by the pro-oxidant t-butyl hydroperoxide (t-BHP). SET overexpression in HEK293 cells decreased UCP1 and increased UCP2 and UCP3 (S/L) mRNA and protein levels, whilst also preventing lipid peroxidation and decreasing the content of cellular ATP. SET overexpression also (i) decreased the area of mitochondria and increased the number of organelles and lysosomes, (ii) increased mitochondrial fission, as demonstrated by increased FIS1 mRNA and FIS-1 protein levels, an apparent accumulation of DRP-1 protein, and an increase in the VDAC protein level, and (iii) reduced autophagic flux, as demonstrated by a decrease in LC3B lipidation (LC3B-II) in the presence of chloroquine. Therefore, SET overexpression in HEK293 cells promotes mitochondrial fission and reduces autophagic flux in apparent association with up-regulation of UCP2 and UCP3; this implies a potential involvement in cellular processes that are deregulated such as in Alzheimer's disease and cancer.

  7. Effects of Death Education on Conscious and Unconscious Death Anxiety.

    ERIC Educational Resources Information Center

    Hayslip, Bert, Jr.; And Others

    1994-01-01

    Adults (n=162) varying in extent of participation in didactic or experiential forms of death education versus those who had no such exposure to death and dying-related issues completed measures of conscious and unconscious death fears. Findings suggest that didactic death education was effective in altering death anxiety, although effects were…

  8. [Death experience. Antidote against fear to death].

    PubMed

    Fericgla, Josep M

    2003-12-01

    Fortunately, anthropology has brought to our modern society a higher interest for mankind's cultural dimension and the values which each people employ in order to make sense out of the changes which occur during our lives. It is this cultural dimension which permits men to develop our innate capacities and to become humans. However, in order to achieve this, we need experiences which are codified and interpreted by a values system which each individual has made his/her own. Some of these experiences take place inside cultural mores constructed expressly so that they are useful for one's lifestyle; these are known as rites. A rite, therefore, is an experience which leaves an impression, which implies social and biographical changes, which provides meaning to human beings' universal interests. Nonetheless, since rites usually are organized by diverse religions, it is convenient, as we enter the 21st Century, to speak about Experiences which Activate Structures as means to approach, to come to grasp with, some of the great causes of anxiety in humans: death and insanity. These Experiences which Activate Structures allow us to subjectively experiment, to conquer our fears and to be more conscious of our here and our now. Workshops on the Living Integration of One's Own Death are included in this context as an appropriate forum through which to approach death with knowledge and serenity, inducing changes in our own lifestyle as well and helping us to overcome situations of existential blockage.

  9. Cap-independent translation by DAP5 controls cell fate decisions in human embryonic stem cells.

    PubMed

    Yoffe, Yael; David, Maya; Kalaora, Rinat; Povodovski, Lital; Friedlander, Gilgi; Feldmesser, Ester; Ainbinder, Elena; Saada, Ann; Bialik, Shani; Kimchi, Adi

    2016-09-01

    Multiple transcriptional and epigenetic changes drive differentiation of embryonic stem cells (ESCs). This study unveils an additional level of gene expression regulation involving noncanonical, cap-independent translation of a select group of mRNAs. This is driven by death-associated protein 5 (DAP5/eIF4G2/NAT1), a translation initiation factor mediating IRES-dependent translation. We found that the DAP5 knockdown from human ESCs (hESCs) resulted in persistence of pluripotent gene expression, delayed induction of differentiation-associated genes in different cell lineages, and defective embryoid body formation. The latter involved improper cellular organization, lack of cavitation, and enhanced mislocalized apoptosis. RNA sequencing of polysome-associated mRNAs identified candidates with reduced translation efficiency in DAP5-depleted hESCs. These were enriched in mitochondrial proteins involved in oxidative respiration, a pathway essential for differentiation, the significance of which was confirmed by the aberrant mitochondrial morphology and decreased oxidative respiratory activity in DAP5 knockdown cells. Further analysis identified the chromatin modifier HMGN3 as a cap-independent DAP5 translation target whose knockdown resulted in defective differentiation. Thus, DAP5-mediated translation of a specific set of proteins is critical for the transition from pluripotency to differentiation, highlighting the importance of cap-independent translation in stem cell fate decisions.

  10. Cap-independent translation by DAP5 controls cell fate decisions in human embryonic stem cells.

    PubMed

    Yoffe, Yael; David, Maya; Kalaora, Rinat; Povodovski, Lital; Friedlander, Gilgi; Feldmesser, Ester; Ainbinder, Elena; Saada, Ann; Bialik, Shani; Kimchi, Adi

    2016-09-01

    Multiple transcriptional and epigenetic changes drive differentiation of embryonic stem cells (ESCs). This study unveils an additional level of gene expression regulation involving noncanonical, cap-independent translation of a select group of mRNAs. This is driven by death-associated protein 5 (DAP5/eIF4G2/NAT1), a translation initiation factor mediating IRES-dependent translation. We found that the DAP5 knockdown from human ESCs (hESCs) resulted in persistence of pluripotent gene expression, delayed induction of differentiation-associated genes in different cell lineages, and defective embryoid body formation. The latter involved improper cellular organization, lack of cavitation, and enhanced mislocalized apoptosis. RNA sequencing of polysome-associated mRNAs identified candidates with reduced translation efficiency in DAP5-depleted hESCs. These were enriched in mitochondrial proteins involved in oxidative respiration, a pathway essential for differentiation, the significance of which was confirmed by the aberrant mitochondrial morphology and decreased oxidative respiratory activity in DAP5 knockdown cells. Further analysis identified the chromatin modifier HMGN3 as a cap-independent DAP5 translation target whose knockdown resulted in defective differentiation. Thus, DAP5-mediated translation of a specific set of proteins is critical for the transition from pluripotency to differentiation, highlighting the importance of cap-independent translation in stem cell fate decisions. PMID:27664238

  11. Unusual sudden death.

    PubMed Central

    Warren, J. V.

    1985-01-01

    In contrast to usual sudden death seen in the course of coronary artery disease, individuals dying suddenly from other causes form a complex array of situations. In some the causes are readily identifiable. No simple pattern is available to identify the potential candidate, but on review of the many causes some moves by the physician may be helpful. For example, a more complete physical evaluation of young individuals participating in competitive athletics is in order. This is particularly true if the athlete reports an episode of unexplained syncope. This may well be the warning of a propensity towards sudden death under physical and emotional stress. Knowledge of the specific problems in underwater swimming and diving, in high altitude exposure and in various circumstances such as certain weight reduction diets and industrial exposures may lead to control of some types of unusual sudden death. Clearly, more studies are needed to give answers in so called crib death. As the incidence of usual sudden death falls, these unusual forms of sudden death will represent a more important fraction of sudden death in general. PMID:6537674

  12. Calcium signaling as a mediator of cell energy demand and a trigger to cell death.

    PubMed

    Bhosale, Gauri; Sharpe, Jenny A; Sundier, Stephanie Y; Duchen, Michael R

    2015-09-01

    Calcium signaling is pivotal to a host of physiological pathways. A rise in calcium concentration almost invariably signals an increased cellular energy demand. Consistent with this, calcium signals mediate a number of pathways that together serve to balance energy supply and demand. In pathological states, calcium signals can precipitate mitochondrial injury and cell death, especially when coupled to energy depletion and oxidative or nitrosative stress. This review explores the mechanisms that couple cell signaling pathways to metabolic regulation or to cell death. The significance of these pathways is exemplified by pathological case studies, such as those showing loss of mitochondrial calcium uptake 1 in patients and ischemia/reperfusion injury.

  13. Calcium signaling as a mediator of cell energy demand and a trigger to cell death

    PubMed Central

    Bhosale, Gauri; Sharpe, Jenny A.; Sundier, Stephanie Y.

    2015-01-01

    Calcium signaling is pivotal to a host of physiological pathways. A rise in calcium concentration almost invariably signals an increased cellular energy demand. Consistent with this, calcium signals mediate a number of pathways that together serve to balance energy supply and demand. In pathological states, calcium signals can precipitate mitochondrial injury and cell death, especially when coupled to energy depletion and oxidative or nitrosative stress. This review explores the mechanisms that couple cell signaling pathways to metabolic regulation or to cell death. The significance of these pathways is exemplified by pathological case studies, such as those showing loss of mitochondrial calcium uptake 1 in patients and ischemia/reperfusion injury. PMID:26375864

  14. Unnatural sudden infant death

    PubMed Central

    Meadow, R.

    1999-01-01

    AIM—To identify features to help paediatricians differentiate between natural and unnatural infant deaths.
METHOD—Clinical features of 81 children judged by criminal and family courts to have been killed by their parents were studied. Health and social service records, court documents, and records from meetings with parents, relatives, and social workers were studied.
RESULTS—Initially, 42 children had been certified as dying from sudden infant death syndrome (SIDS), and 29 were given another cause of natural death. In 24 families, more than one child died; 58died before the age of 6 months and most died in the afternoon or evening. Seventy per cent had experienced unexplained illnesses; over half were admitted to hospital within the previous month, and 15 had been discharged within 24 hours of death. The mother, father, or both were responsible for death in 43, five, and two families, respectively. Most homes were disadvantaged—no regular income, receiving income support—and mothers smoked. Half the perpetrators had a history of somatising or factitious disorder. Death was usually by smothering and 43% of children had bruises, petechiae, or blood on the face.
CONCLUSIONS—Although certain features are indicative of unnatural infant death, some are also associated with SIDS. Despite the recent reduction in numbers of infants dying suddenly, inadequacies in the assessment of their deaths exist. Until a thorough postmortem examination is combined with evaluation of the history and circumstances of death by an experienced paediatrician, most cases of covert fatal abuse will go undetected. The term SIDS requires revision or abandonment.

 PMID:10325752

  15. Eaten to death

    PubMed Central

    Nelson, Charles; Baehrecke, Eric H.

    2014-01-01

    Macro-autophagy (hereafter referred to as autophagy) delivers cytoplasmic material to the lysosome for degradation, and has been implicated in many cellular processes, including stress, infection, survival, and death. While the regulation and role that autophagy plays in stress, infection, and survival is apparent, the regulation of and role that autophagy has during cell death remains relatively unclear. In this review, we highlight what is known about the role that autophagy can play during physiological cell death, and discuss the implications of better understanding cellular destruction that involves autophagy. PMID:25323556

  16. Death writ large.

    PubMed

    Kastenbaum, Robert

    2004-05-01

    Mainstream thanatology has devoted its efforts to improving the understanding, care, and social integration of people who are confronted with life-threatening illness or bereavement. This article suggests that it might now be time to expand the scope and mission to include large-scale death and death that occurs through complex and multi-domain processes. Obstacles to developing a systematic macrothanatology are identified. The 9-11-01 terrorist attacks on America are discussed as an example of mass death with complex correlates and consequences. Other examples are taken from the realms of war, disease, disaster, and extinction.

  17. Negotiating natural death in intensive care.

    PubMed

    Seymour, J E

    2000-10-01

    Recent empirical evidence of barriers to palliative care in acute hospital settings shows that dying patients may receive invasive medical treatments immediately before death, in spite of evidence of their poor prognosis being available to clinicians. The difficulties of ascertaining treatment preferences, predicting the trajectory of dying in critically ill people, and assessing the degree to which further interventions are futile are well documented. Further, enduring ethical complexities attending end of life care mean that the process of withdrawing or withholding medical care is associated with significant problems for clinical staff. Specific difficulties attend the legitimation of treatment withdrawal, the perceived differences between 'killing' and 'letting die' and the cultural constraints which attend the orchestration of 'natural' death in situations where human agency is often required before death can follow dying. This paper draws on ethnographic research to examine the way in which these problems are resolved during medical work within intensive care. Building on insights from the literature, an analysis of observational case study data is presented which suggests that the negotiation of natural death in intensive care hinges upon four strategies. These, which form a framework with which to interpret social interaction between physicians during end of life decision-making in intensive care, are as follows: firstly, the establishment of a 'technical' definition of dying--informed by results of investigations and monitoring equipment--over and above 'bodily' dying informed by clinical experience. Secondly, the alignment of the trajectories of technical and bodily dying to ensure that the events of non-treatment have no perceived causative link to death. Thirdly, the balancing of medical action with non-action, allowing a diffusion of responsibility for death to the patient's body; and lastly, the incorporation of patient's companions and nursing staff

  18. Children's Death Concepts and Ethnicity.

    ERIC Educational Resources Information Center

    Wass, Hannelore; Towry, Betty J.

    1980-01-01

    Relationships between death concepts of Black and White children and their racial status were examined. Lower-middle-class elementary children completed a four-item questionnaire on death. Most children defined death as the end of living and listed physical causes as the explanation of death. In general, children's death concepts were similar.…

  19. The interactive roles of zinc and calcium in mitochondrial dysfunction and neurodegeneration

    PubMed Central

    Pivovarova, Natalia B.; Stanika, Ruslan I.; Kazanina, Galina; Villanueva, Idalis; Andrews, S. Brian

    2013-01-01

    Zinc has been implicated in neurodegeneration following ischemia. In analogy to calcium, zinc has been proposed to induce toxicity via mitochondrial dysfunction, but the relative role of each cation in mitochondrial damage is unclear. Here we report that under conditions mimicking ischemia in hippocampal neurons — normal (2 mM) calcium plus elevated (>100 μM) exogenous zinc — mitochondrial dysfunction evoked by glutamate, kainate or direct depolarization is, despite significant zinc uptake, primarily governed by calcium. Thus, robust mitochondrial ion accumulation, swelling, depolarization and ROS generation were only observed after toxic stimulation in calcium-containing media. This contrasts with the lack of any mitochondrial response in zinc-containing but calcium-free medium, even though zinc uptake and toxicity were strong under these conditions. Indeed, abnormally high, ionophore-induced zinc uptake was necessary to elicit any mitochondrial depolarization. In calcium- and zinc-containing media, depolarization-induced zinc uptake facilitated cell death and enhanced accumulation of mitochondrial calcium, which localized to characteristic matrix precipitates. Some of these contained detectable amounts of zinc. Together these data indicate that zinc uptake is generally insufficient to trigger mitochondrial dysfunction, so that mechanism(s) of zinc toxicity must be different from that of calcium. PMID:24127746

  20. The interactive roles of zinc and calcium in mitochondrial dysfunction and neurodegeneration.

    PubMed

    Pivovarova, Natalia B; Stanika, Ruslan I; Kazanina, Galina; Villanueva, Idalis; Andrews, S Brian

    2014-02-01

    Zinc has been implicated in neurodegeneration following ischemia. In analogy with calcium, zinc has been proposed to induce toxicity via mitochondrial dysfunction, but the relative role of each cation in mitochondrial damage remains unclear. Here, we report that under conditions mimicking ischemia in hippocampal neurons - normal (2 mM) calcium plus elevated (> 100 μM) exogenous zinc - mitochondrial dysfunction evoked by glutamate, kainate or direct depolarization is, despite significant zinc uptake, primarily governed by calcium. Thus, robust mitochondrial ion accumulation, swelling, depolarization, and reactive oxygen species generation were only observed after toxic stimulation in calcium-containing media. This contrasts with the lack of any mitochondrial response in zinc-containing but calcium-free medium, even though zinc uptake and toxicity were strong under these conditions. Indeed, abnormally high, ionophore-induced zinc uptake was necessary to elicit any mitochondrial depolarization. In calcium- and zinc-containing media, depolarization-induced zinc uptake facilitated cell death and enhanced accumulation of mitochondrial calcium, which localized to characteristic matrix precipitates. Some of these contained detectable amounts of zinc. Together these data indicate that zinc uptake is generally insufficient to trigger mitochondrial dysfunction, so that mechanism(s) of zinc toxicity must be different from that of calcium.

  1. Caspase-like activity in programmed nuclear death during conjugation of Tetrahymena thermophila.

    PubMed

    Kobayashi, T; Endoh, H

    2003-06-01

    Apoptosis, or programmed cell death, is common in a variety of eucaryotes, from unicellular protozoa to vertebrates. The ciliated protozoan Tetrahymena thermophila has a unique apoptosis-like nuclear death during conjugation, called programmed nuclear death. This death program involves nuclear condensation (pyknosis) and oligonucleosomal DNA fragmentation in the parental macronucleus. Subsequently, the condensed nucleus is entirely resorbed in the autophagosome. Here we demonstrate that caspase-8- and -9-like activity was detected, but no caspase-3-like activity, by in vitro assay during the nuclear resorption process, suggesting that caspase-like activity is associated with both programmed cell death and apoptosis-like nuclear death in Tetrahymena. The use of indicator dye to detect the loss of mitochondrial membrane potential suggested the uptake of mitochondria and the degenerating macronucleus by the autophagosome. An involvement of mitochondria in the programmed nuclear death is discussed.

  2. Transient mitochondrial permeability transition mediates excitotoxicity in glutamate-sensitive NSC34D motor neuron-like cells

    PubMed Central

    Liu, Xiaoyun; Xu, Shangcheng; Wang, Pei; Wang, Wang

    2015-01-01

    Excitotoxicity plays a critical role in neurodegenerative disease. Cytosolic calcium overload and mitochondrial dysfunction are among the major mediators of high level glutamate-induced neuron death. Here, we show that the transient opening of mitochondrial permeability transition pore (tMPT) bridges cytosolic calcium signaling and mitochondrial dysfunction and mediates glutamate-induced neuron death. Incubation of the differentiated motor neuron-like NSC34D cells with glutamate (1 mM) acutely induces cytosolic calcium transient (30% increase). Glutamate also stimulates tMPT opening, as reflected by a 2-fold increase in the frequency of superoxide flash, a bursting superoxide production event in individual mitochondria coupled to tMPT opening. The glutamate-induced tMPT opening is attenuated by suppressing cytosolic calcium influx and abolished by inhibiting mitochondrial calcium uniporter (MCU) with Ru360 (100 µM) or MCU shRNA. Further, increased cytosolic calcium is sufficient to induce tMPT in a mitochondrial calcium dependent manner. Finally, chronic glutamate incubation (24 hr) persistently elevates the probability of tMPT opening, promotes oxidative stress and induces neuron death. Attenuating tMPT activity or inhibiting MCU protects NSC34D cells from glutamate-induced cell death. These results indicate that high level glutamate-induced neuron toxicity is mediated by tMPT, which connects increased cytosolic calcium signal to mitochondrial dysfunction. PMID:26024861

  3. Death and Grief

    MedlinePlus

    ... for Parents for Kids for Teens Teens Home Body Mind Sexual Health Food & Fitness Diseases & Conditions Infections Q& ... a death or loss. Grief can affect our body, mind, emotions, and spirit. People might notice or show ...

  4. Hitler's Death Camps.

    ERIC Educational Resources Information Center

    Wieser, Paul

    1995-01-01

    Presents a high school lesson on Hitler's death camps and the widespread policy of brutality and oppression against European Jews. Includes student objectives, instructional procedures, and a chart listing the value of used clothing taken from the Jews. (CFR)

  5. Death and Wheatgrass

    ERIC Educational Resources Information Center

    Coleman, Jon T.

    2005-01-01

    The death of his father prompts the author and university professor to reflect on the acts of grieving and teaching. He offers a tribute to his deceased father while commenting on the importance of teaching in his life.

  6. Triggering of Programmed Erythrocyte Death by Alantolactone

    PubMed Central

    Alzoubi, Kousi; Calabrò, Salvatrice; Egler, Jasmin; Faggio, Caterina; Lang, Florian

    2014-01-01

    The sesquiterpene alantolactone counteracts malignancy, an effect at least in part due to stimulation of suicidal death or apoptosis of tumor cells. Signaling of alantolactone induced apoptosis involves altered gene expression and mitochondrial depolarization. Erythrocytes lack mitochondria and nuclei but may enter suicidal death or eryptosis, which is characterized by cell shrinkage and cell membrane scrambling with phosphatidylserine exposure at the erythrocyte surface. Cellular mechanisms involved in triggering of eryptosis include increase of cytosolic Ca2+-activity ([Ca2+]i) and oxidative stress. The present study explored, whether alantolactone stimulates eryptosis. To this end, erythrocyte volume was estimated from forward scatter, phosphatidylserine-exposure at the erythrocyte surface from FITC-annexin-V-binding, [Ca2+]i from Fluo3-fluorescence, ceramide abundance from binding of fluorescent antibodies, and oxidative stress from 2',7'-dichlorodihydrofluorescein-diacetate (DCFDA) fluorescence. As a result, a 48 h exposure of human erythrocytes to alantolactone (≥20 μM) significantly decreased erythrocyte forward scatter and increased the percentage of annexin-V-binding cells. Alantolactone significantly increased Fluo3 fluorescence (60 μM), ceramide abundance (60 μM) and DCFDA fluorescence (≥40 μM). The effect of alantolactone (60 μM) on annexin-V-binding was not significantly modified by removal of extracellular Ca2+. In conclusion, alantolactone stimulates suicidal erythrocyte death or eryptosis, an effect paralleled by increase of [Ca2+]i, ceramide abundance and oxidative stress. PMID:25533522

  7. Autoerotic deaths: four cases.

    PubMed

    Cooke, C T; Cadden, G A; Margolius, K A

    1994-07-01

    We describe the circumstances and post mortem medical findings of 4 unusual fatalities where death occurred during autoerotic practice. Three cases occurred in young to middle-aged men--hanging, electrocution and inhalation of a zucchini. The manner of death in each was accidental. The fourth case was an elderly man who died of ischemic heart disease, apparently whilst masturbating with a vacuum cleaner and a hair dryer.

  8. Mitochondrial toxicity and HIV therapy

    PubMed Central

    White, A.

    2001-01-01

    Nucleoside reverse transcriptase inhibitors (NRTIs) remain the cornerstone of highly active antiretroviral therapy (HAART) combination regimens. However, it has been known for some time that these agents have the potential to cause varied side effects, many of which are thought to be due to their effects on mitochondria. Mitochondria, the key energy generating organelles in the cell, are unique in having their own DNA, a double stranded circular genome of about 16 000 bases. There is a separate enzyme present inside the cell that replicates mitochondrial DNA, polymerase gamma. NRTIs can affect the function of this enzyme and this may lead to depletion of mitochondrial DNA or qualitative changes. The study of inherited mitochondrial diseases has led to further understanding of the consequences of mutations or depletion in mitochondrial DNA. Key among these is the realisation that there may be substantial heteroplasmy among mitochondria within a given cell, and among cells in a particular tissue. The unpredictable nature of mitochondrial segregation during cellular replication makes it difficult to predict the likelihood of dysfunction in a given tissue. In addition, there is a threshold effect for the expression of mitochondrial dysfunction, both at the mitochondrial and cellular level. Various clinical and in vitro studies have suggested that NRTIs are associated with mitochondrial dysfunction in different tissues, although the weight of evidence is limited in many cases. The heterogeneity in the tissues affected by the different drugs raises interesting questions, and possible explanations include differential distribution or activation of these agents. This article reviews the major recognised toxicities associated with NRTI therapy and evidence for mitochondrial dysfunction in these complications. Data were identified through searching of online databases including Medline and Current Contents for relevant articles, along with abstracts and posters from recent

  9. Targeting a mitochondrial potassium channel to fight cancer.

    PubMed

    Leanza, Luigi; Venturini, Elisa; Kadow, Stephanie; Carpinteiro, Alexander; Gulbins, Erich; Becker, Katrin Anne

    2015-07-01

    Although chemotherapy is able to cure many patients with malignancies, it still also often fails. Therefore, novel approaches and targets for chemotherapeutic treatment of malignancies are urgently required. Recent studies demonstrated the expression of several potassium channels in the inner mitochondrial membrane. Among them the voltage gated potassium channel Kv1.3 and the big-potassium (BK) channel were shown to directly function in cell death by serving as target for pro-apoptotic Bax and Bak proteins. Here, we discuss the role of mitochondrial potassium channel Kv1.3 (mitoKv1.3) in cell death and its potential function in treatment of solid tumors, leukemia and lymphoma. Bax and Bak inhibit mitoKv1.3 by directly binding into the pore of the channel, by a toxin-like mechanism. Inhibition of mitoKv1.3 results in an initial hyperpolarization of the inner mitochondrial membrane that triggers the production of reactive oxygen species (ROS). ROS in turn induce a release of cytochrome c from the cristae of the inner mitochondrial membrane and an activation of the permeability transition pore, resulting in opening of the intrinsic apoptotic cell death. Since mitoKv1.3 functions downstream of pro-apoptotic Bax and Bak, compounds that directly inhibit mitoKv1.3 may serve as a new class of drugs for treatment of tumors, even with an altered expression of either pro- or anti-apoptotic Bcl-2 protein family members. This was successfully proven by the in vivo treatment of mouse melanoma and ex vivo human chronic leukemia B cells with inhibitors of mitoKv1.3.

  10. Funerals against death

    PubMed Central

    Bailey, Tara; Walter, Tony

    2016-01-01

    While anthropological studies in non-Western societies show how funerals protect the community from the threat of death, sociological studies of British funerals have so far focused on meanings for the private family. The article reports on results from a Mass Observation directive – the first British study to focus specifically on the entire funeral congregation – and shows how attendees experience the contemporary life-centred funeral as a symbolic conquest of death. While the eulogy’s accuracy is important, even more so – at least for some – is its authenticity, namely that the speaker has personal knowledge of the deceased. Whereas Davies analyses the power of professionally delivered ritual words against death, our data reveals how admired is the courage exercised by non-professionals in speaking against death, however faltering their words. Further, the very presence of a congregation whose members have known the deceased in diverse ways embodies a configurational eulogy, which we term relationships against death. We thus argue that funerals symbolically conquer death not only through words delivered by ritual specialists, but also through those who knew the deceased congregating and speaking. PMID:27019605

  11. Autophagic cell death exists

    PubMed Central

    Clarke, Peter G.H.; Puyal, Julien

    2012-01-01

    The term autophagic cell death (ACD) initially referred to cell death with greatly enhanced autophagy, but is increasingly used to imply a death-mediating role of autophagy, as shown by a protective effect of autophagy inhibition. In addition, many authors require that autophagic cell death must not involve apoptosis or necrosis. Adopting these new and restrictive criteria, and emphasizing their own failure to protect human osteosarcoma cells by autophagy inhibition, the authors of a recent Editor’s Corner article in this journal argued for the extreme rarity or nonexistence of autophagic cell death. We here maintain that, even with the more stringent recent criteria, autophagic cell death exists in several situations, some of which were ignored by the Editor’s Corner authors. We reject their additional criterion that the autophagy in ACD must be the agent of ultimate cell dismantlement. And we argue that rapidly dividing mammalian cells such as cancer cells are not the most likely situation for finding pure ACD. PMID:22652592

  12. Classification of cell death

    PubMed Central

    Kroemer, G; Galluzzi, L; Vandenabeele, P; Abrams, J; Alnemri, ES; Baehrecke, EH; Blagosklonny, MV; El-Deiry, WS; Golstein, P; Green, DR; Hengartner, M; Knight, RA; Kumar, S; Lipton, SA; Malorni, W; Nuñez, G; Peter, ME; Tschopp, J; Yuan, J; Piacentini, M; Zhivotovsky, B; Melino, G

    2009-01-01

    Different types of cell death are often defined by morphological criteria, without a clear reference to precise biochemical mechanisms. The Nomenclature Committee on Cell Death (NCCD) proposes unified criteria for the definition of cell death and of its different morphologies, while formulating several caveats against the misuse of words and concepts that slow down progress in the area of cell death research. Authors, reviewers and editors of scientific periodicals are invited to abandon expressions like ‘percentage apoptosis’ and to replace them with more accurate descriptions of the biochemical and cellular parameters that are actually measured. Moreover, at the present stage, it should be accepted that caspase-independent mechanisms can cooperate with (or substitute for) caspases in the execution of lethal signaling pathways and that ‘autophagic cell death’ is a type of cell death occurring together with (but not necessarily by) autophagic vacuolization. This study details the 2009 recommendations of the NCCD on the use of cell death-related terminology including ‘entosis’, ‘mitotic catastrophe’, ‘necrosis’, ‘necroptosis’ and ‘pyroptosis’. PMID:18846107

  13. Death obsession in Palestinians.

    PubMed

    Abdel-Khalek, Ahmed M; Al-Arja, Nahida S; Abdalla, Taysir

    2006-04-01

    The authors explored death obsession level and correlates among a sample (N = 601) of Palestinians living in the city of Beit Jala, the village of Al-Khader, and the Aida refugee camp in the Bethlehem area. They live in war conditions; the houses of half of them have been demolished. The Death Obsession Scale (DOS) was administered. Its alpha reliability was .92, denoting high internal consistency. Among women, it yielded 1 factor, (General Death Obsession), whereas among men it yielded 3 factors: Death Rumination, Death Dominance, and Death Idea Repetition. Palestinian men and women attained significantly lower DOS mean scores than participants from 4 Arab countries: Egypt, Kuwait, Syria, and Lebanon in 7 out of 8 comparisons. However, Palestinian women had significantly higher DOS mean score than their Spanish, American and British counterparts, whereas Palestinian men had significantly higher mean DOS score than Spanish peers. The low DOS scores of Palestinians, in proportion to other Arab samples, may reflect their adaptation to strife and violence.

  14. Metabolic control of T-cell activation and death in SLE

    PubMed Central

    Fernandez, David; Perl, Andras

    2009-01-01

    Systemic lupus erythematosus (SLE) is characterized by abnormal T-cell activation and death, processes which are crucially dependent on the controlled production of reactive oxygen intermediates (ROI) and of ATP in mitochondria. The mitochondrial transmembrane potential (Δψm) has conclusively emerged as a critical checkpoint of ATP synthesis and cell death. Lupus T cells exhibit persistent elevation of Δψm or mitochondrial hyperpolarization (MHP) as well as depletion of ATP and glutathione which decrease activation-induced apoptosis and instead predispose T cells for necrosis, thus stimulating inflammation in SLE. NO-induced mitochondrial biogenesis in normal T cells accelerates the rapid phase and reduces the plateau of Ca2+ influx upon CD3/CD28 co-stimulation, thus mimicking the Ca2+ signaling profile of lupus T cells. Treatment of SLE patients with rapamycin improves disease activity, normalizes CD3/CD28-induced Ca2+ fluxing but fails to affect MHP, suggesting that altered Ca2+ fluxing is downstream or independent of mitochondrial dysfunction. Understanding the molecular basis and consequences of MHP is essential for controlling T-cell activation and death signaling in SLE. Lupus T cells exhibit mitochondrial dysfunctionMitochondrial hyperpolarization (MHP) and ATP depletion predispose lupus T cells to death by necrosis which is pro-inflammatoryMHP is caused by depletion of glutathione and exposure to nitric oxide (NO)NO-induced mitochondrial biogenesis regenerates the Ca2+ signaling profile of lupus T cellsRapamycin treatment normalizes Ca2+ fluxing but not MHP, suggesting that the mammalian target of rapamycin, acts as a sensor and effector of MHP in SLE PMID:18722557

  15. Sealing the mitochondrial respirasome.

    PubMed

    Winge, Dennis R

    2012-07-01

    The mitochondrial respiratory chain is organized within an array of supercomplexes that function to minimize the generation of reactive oxygen species (ROS) during electron transfer reactions. Structural models of supercomplexes are now known. Another recent advance is the discovery of non-OXPHOS complex proteins that appear to adhere to and seal the individual respiratory complexes to form stable assemblages that prevent electron leakage. This review highlights recent advances in our understanding of the structures of supercomplexes and the factors that mediate their stability.

  16. Mitochondrial form and function

    PubMed Central

    Friedman, Jonathan R.; Nunnari, Jodi

    2014-01-01

    Mitochondria are one of the major ancient endomembrane systems in eukaryotic cells. Owing to their ability to produce ATP through respiration, they became a driving force in evolution. As an essential step in the process of eukaryotic evolution, the size of the mitochondrial chromosome was drastically reduced, and the behaviour of mitochondria within eukaryotic cells radically changed. Recent advances have revealed how the organelle’s behaviour has evolved to allow the accurate transmission of its genome and to become responsive to the needs of the cell and its own dysfunction. PMID:24429632

  17. Organization of the Mitochondrial Apoptotic BAK Pore

    PubMed Central

    Aluvila, Sreevidya; Mandal, Tirtha; Hustedt, Eric; Fajer, Peter; Choe, Jun Yong; Oh, Kyoung Joon

    2014-01-01

    The multidomain pro-apoptotic Bcl-2 family proteins BAK and BAX are believed to form large oligomeric pores in the mitochondrial outer membrane during apoptosis. Formation of these pores results in the release of apoptotic factors including cytochrome c from the intermembrane space into the cytoplasm, where they initiate the cascade of events that lead to cell death. Using the site-directed spin labeling method of electron paramagnetic resonance (EPR) spectroscopy, we have determined the conformational changes that occur in BAK when the protein targets to the membrane and forms pores. The data showed that helices α1 and α6 disengage from the rest of the domain, leaving helices α2-α5 as a folded unit. Helices α2-α5 were shown to form a dimeric structure, which is structurally homologous to the recently reported BAX “BH3-in-groove homodimer.” Furthermore, the EPR data and a chemical cross-linking study demonstrated the existence of a hitherto unknown interface between BAK BH3-in-groove homodimers in the oligomeric BAK. This novel interface involves the C termini of α3 and α5 helices. The results provide further insights into the organization of the BAK oligomeric pores by the BAK homodimers during mitochondrial apoptosis, enabling the proposal of a BAK-induced lipidic pore with the topography of a “worm hole.” PMID:24337568

  18. Arabidopsis ACCELERATED CELL DEATH2 Modulates Programmed Cell DeathW⃞

    PubMed Central

    Yao, Nan; Greenberg, Jean T.

    2006-01-01

    The Arabidopsis thaliana chloroplast protein ACCELERATED CELL DEATH2 (ACD2) modulates the amount of programmed cell death (PCD) triggered by Pseudomonas syringae and protoporphyrin IX (PPIX) treatment. In vitro, ACD2 can reduce red chlorophyll catabolite, a chlorophyll derivative. We find that ACD2 shields root protoplasts that lack chlorophyll from light- and PPIX-induced PCD. Thus, chlorophyll catabolism is not obligatory for ACD2 anti-PCD function. Upon P. syringae infection, ACD2 levels and localization change in cells undergoing PCD and in their close neighbors. Thus, ACD2 shifts from being largely in chloroplasts to partitioning to chloroplasts, mitochondria, and, to a small extent, cytosol. ACD2 protects cells from PCD that requires the early mitochondrial oxidative burst. Later, the chloroplasts of dying cells generate NO, which only slightly affects cell viability. Finally, the mitochondria in dying cells have dramatically altered movements and cellular distribution. Overproduction of both ACD2 (localized to mitochondria and chloroplasts) and ascorbate peroxidase (localized to chloroplasts) greatly reduces P. syringae–induced PCD, suggesting a pro-PCD role for mitochondrial and chloroplast events. During infection, ACD2 may bind to and/or reduce PCD-inducing porphyrin-related molecules in mitochondria and possibly chloroplasts that generate reactive oxygen species, cause altered organelle behavior, and activate a cascade of PCD-inducing events. PMID:16387834

  19. Molecular Genetics of Mitochondrial Disorders

    ERIC Educational Resources Information Center

    Wong, Lee-Jun C.

    2010-01-01

    Mitochondrial respiratory chain (RC) disorders (RCDs) are a group of genetically and clinically heterogeneous diseases because of the fact that protein components of the RC are encoded by both mitochondrial and nuclear genomes and are essential in all cells. In addition, the biogenesis, structure, and function of mitochondria, including DNA…

  20. CCN6 regulates mitochondrial function.

    PubMed

    Patra, Milan; Mahata, Sushil K; Padhan, Deepesh K; Sen, Malini

    2016-07-15

    Despite established links of CCN6, or Wnt induced signaling protein-3 (WISP3), with progressive pseudo rheumatoid dysplasia, functional characterization of CCN6 remains incomplete. In light of the documented negative correlation between accumulation of reactive oxygen species (ROS) and CCN6 expression, we investigated whether CCN6 regulates ROS accumulation through its influence on mitochondrial function. We found that CCN6 localizes to mitochondria, and depletion of CCN6 in the chondrocyte cell line C-28/I2 by using siRNA results in altered mitochondrial electron transport and respiration. Enhanced electron transport chain (ETC) activity of CCN6-depleted cells was reflected by increased mitochondrial ROS levels in association with augmented mitochondrial ATP synthesis, mitochondrial membrane potential and Ca(2+) Additionally, CCN6-depleted cells display ROS-dependent PGC1α (also known as PPARGC1A) induction, which correlates with increased mitochondrial mass and volume density, together with altered mitochondrial morphology. Interestingly, transcription factor Nrf2 (also known as NFE2L2) repressed CCN6 expression. Taken together, our results suggest that CCN6 acts as a molecular brake, which is appropriately balanced by Nrf2, in regulating mitochondrial function. PMID:27252383

  1. Mitochondrial genomes as living 'fossils'.

    PubMed

    Small, Ian

    2013-04-15

    The huge variation between mitochondrial genomes makes untangling their evolutionary histories difficult. Richardson et al. report on the remarkably unaltered 'fossil' genome of the tulip tree, giving us many clues as to how the mitochondrial genomes of flowering plants have evolved over the last 150 million years, and raising questions about how such extraordinary sequence conservation can be maintained.

  2. DJ-1 protects against cell death following acute cardiac ischemia–reperfusion injury

    PubMed Central

    Dongworth, R K; Mukherjee, U A; Hall, A R; Astin, R; Ong, S-B; Yao, Z; Dyson, A; Szabadkai, G; Davidson, S M; Yellon, D M; Hausenloy, D J

    2014-01-01

    Novel therapeutic targets are required to protect the heart against cell death from acute ischemia–reperfusion injury (IRI). Mutations in the DJ-1 (PARK7) gene in dopaminergic neurons induce mitochondrial dysfunction and a genetic form of Parkinson's disease. Genetic ablation of DJ-1 renders the brain more susceptible to cell death following ischemia–reperfusion in a model of stroke. Although DJ-1 is present in the heart, its role there is currently unclear. We sought to investigate whether mitochondrial DJ-1 may protect the heart against cell death from acute IRI by preventing mitochondrial dysfunction. Overexpression of DJ-1 in HL-1 cardiac cells conferred the following beneficial effects: reduced cell death following simulated IRI (30.4±4.7% with DJ-1 versus 52.9±4.7% in control; n=5, P<0.05); delayed mitochondrial permeability transition pore (MPTP) opening (a critical mediator of cell death) (260±33 s with DJ-1 versus 121±12 s in control; n=6, P<0.05); and induction of mitochondrial elongation (81.3±2.5% with DJ-1 versus 62.0±2.8% in control; n=6 cells, P<0.05). These beneficial effects of DJ-1 were absent in cells expressing the non-functional DJ-1L166P and DJ-1Cys106A mutants. Adult mice devoid of DJ-1 (KO) were found to be more susceptible to cell death from in vivo IRI with larger myocardial infarct sizes (50.9±3.5% DJ-1 KO versus 41.1±2.5% in DJ-1 WT; n≥7, P<0.05) and resistant to cardioprotection by ischemic preconditioning. DJ-1 KO hearts showed increased mitochondrial fragmentation on electron microscopy, although there were no differences in calcium-induced MPTP opening, mitochondrial respiratory function or myocardial ATP levels. We demonstrate that loss of DJ-1 protects the heart from acute IRI cell death by preventing mitochondrial dysfunction. We propose that DJ-1 may represent a novel therapeutic target for cardioprotection. PMID:24577080

  3. [Deaths in hotels].

    PubMed

    Risse, Manfred; Weilbächer, Nadine; Birngruber, Christoph; Verhoff, Marcel A

    2010-01-01

    There are no verified statistics about deaths occurring in hotels, and only a few cases have been described in the literature. A recent case induced us to conduct a systematic search for deaths in hotels in the autopsy reports of the Institute of Legal Medicine in Giessen for the period from 1968 to 2009. This search yielded 22 evaluable cases in which persons had been found dead or had died in hotels. Data evaluated in the study were sex and age of the deceased, reason for the stay in the hotel and cause of death. Among the deaths, 18 were males and 4 females and the average age was 41 and 40 years respectively. 6 of the male guests had died from a natural and 10 from a non-natural cause. In the remaining two cases, the cause of death could not be determined, but as there was no evidence that another party had been involved, the cases were not further investigated. Of the 4 female guests, 3 had died of a natural cause; in one case, the cause of death remained unclear even after morphological and toxicological investigations. Surprisingly, a third of the men were found to be temporarily living in hotels due to social circumstances. This was not true for any of the women. Our retrospective analysis is based on a comparatively small number of deaths in what were mostly hotels in small to medium-sized towns. Interestingly, the gender ratio of 18:4 for deceased men and women was significantly higher than the usual gender ratio of 2:1 found for forensic autopsies. To be able to draw further conclusions, a greater number of cases would have to be analysed, for example by recruiting additional case files from other institutes of legal medicine. This would also open up the option of investigating possible regional variations.

  4. [Mitochondrial neurogastrointestinal encephalopathy disease].

    PubMed

    Benureau, A; Meyer, P; Maillet, O; Leboucq, N; Legras, S; Jeziorski, E; Fournier-Favre, S; Jeandel, C; Gaignard, P; Slama, A; Rivier, F; Roubertie, A; Carneiro, M

    2014-12-01

    Mitochondrial neurogastrointestinal encephalopathy disease (MNGIE) is a rare autosomal-recessive syndrome, resulting from mutations in the TYMP gene, located at 22q13. The mutation induces a thymidine phosphorylase (TP) deficit, which leads to a nucleotide pool imbalance and to instability of the mitochondrial DNA. The clinical picture regroups gastrointestinal dysmotility, cachexia, ptosis, ophthalmoplegia, peripheral neuropathy, and asymptomatic leukoencephalopathy. The prognosis is unfavorable. We present the case of a 14-year-old Caucasian female whose symptoms started in early childhood. The diagnosis was suspected after magnetic resonance imaging (MRI), performed given the atypical features of mental anorexia, which revealed white matter abnormalities. She presented chronic vomiting, postprandial abdominal pain, and problems gaining weight accompanied by cachexia. This diagnosis led to establishing proper care, in particular an enteral and parenteral nutrition program. There is no known specific effective treatment, but numerous studies are in progress. In this article, after reviewing the existing studies, we discuss the main diagnostic and therapeutic aspects of the disease. We argue for the necessity of performing a cerebral MRI given the atypical features of a patient with suspected mental anorexia (or when the clinical pattern of a patient with mental anorexia seems atypical), so that MNGIE can be ruled out. PMID:25282463

  5. Mechanism of Alternariol monomethyl ether-induced mitochondrial apoptosis in human colon carcinoma cells.

    PubMed

    Bensassi, Fatma; Gallerne, Cindy; el Dein, Ossama Sharaf; Hajlaoui, Mohamed Rabeh; Bacha, Hassen; Lemaire, Christophe

    2011-12-18

    Alternariol monomethyl ether (AME) is a major mycotoxin produced by fungi of the genus Alternaria and a common contaminant of food products such as fruits and cereals worldwide. AME can cause serious health problems for animals as well as for humans. In this study, human colon carcinoma cells (HCT116) were used to explore the mechanisms of cell death induced by AME. Exposure of HCT116 cells to AME resulted in significant cytotoxicity manifested by a loss in cell viability mainly mediated by activation of apoptotic process. AME activated the mitochondrial apoptotic pathway evidenced by the opening of the mitochondrial permeability transition pore (PTP), loss of the mitochondrial transmembrane potential (ΔΨm) downstream generation of O(2)(-), cytochrome c release and caspase 9 and 3 activation. Experiments conducted on isolated organelles indicated that AME does not directly target mitochondria to induce PTP-dependent permeabilization of mitochondrial membranes. Moreover, no difference was observed in Bax-KO cells in comparison to parental cells, suggesting that the pro-apoptotic protein Bax is not involved in AME-induced mitochondrial apoptosis. Our findings demonstrate for the first time that AME induces cell death in human colon carcinoma cells by activating the mitochond