Cell Death Pathway (cell + death_pathway)

Distribution by Scientific Domains
Distribution within Life Sciences


Selected Abstracts


HIF-1 and p53: communication of transcription factors under hypoxia

JOURNAL OF CELLULAR AND MOLECULAR MEDICINE, Issue 4 2004
Tobias Schmid
Abstract Oxygen sensing and reactivity to changes in the concentration of oxygen is a fundamental property of cell physiology. The lack of O2 (hypoxia) is transmitted into many adaptive responses, a process that is largely controlled by a transcription factor known as hypoxia inducible factor-1 (HIF-1). More recent reports suggest that besides its traditional regulation via proteasomal degradation other signaling pathways contribute to stability regulation of the HIF-1, subunit and/or HIF-1 transactivation. These regulatory circuits allow for the integration of HIF-1 into scenarios of cell-survival vs. cell-death with the rule of the thumb that short-term mild hypoxia maintains cell viability while prolonged and severe hypoxia provokes cell demise. Cell death pathways are associated with stabilization of the tumor suppressor p53, a response also seen under hypoxic conditions. Here we summarize recent information on accumulation of HIF-1, and p53 under hypoxia and provide a model to explain the communication between HIF-1 and p53 under (patho)physiological conditions. [source]


IFN-, induces apoptosis in mouse embryonic stem cells, a putative mechanism of its embryotoxicity

DEVELOPMENT GROWTH & DIFFERENTIATION, Issue 3 2000
Gang-Ming Zou
It has been reported that interferon (IFN)-, should inhibit in vitro mouse embryo growth by direct cell toxicity. However, the mechanism involved has not been clearly established. In the present study, this question was addressed using the embryonic stem (ES) cell model. It was found that IFN-, induces a dose-dependent apoptosis in ES cells, as assessed by trypan-blue staining, by Annexin-V labeling and DNA analysis. Moreover, IFN-, treatment cooperates with Fas-mediated apoptosis, a phenomenon that has been recently reported. As Bcl-2 oncoprotein functions as a death repressor molecule in an evolutionarily conserved cell death pathway, its expression was analyzed by flow cytometry. It was demonstrated that Bcl-2 is expressed in ES cells. When compared to untreated ES cells, IFN-,-treated, apoptotic cells expressed a lower Bcl-2 level and a normal level of Fas, whereas surviving cells expressed a normal level of Bcl-2 but a lower Fas expression. Altogether, these data suggest that IFN-, may influence early mouse embryo development by promoting apoptosis, which may constitute a novel mechanism of IFN-, embryotoxicity. [source]


Growth hormone-releasing peptide 6 protection of hypothalamic neurons from glutamate excitotoxicity is caspase independent and not mediated by insulin-like growth factor I

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 11 2009
A. Delgado-Rubín
Abstract Treatment of the fetal hypothalamic neuronal cell line RCA-6 with growth hormone-releasing peptide 6, an agonist of the ghrelin receptor, or insulin-like growth factor I activates intracellular signalling cascades associated with anti-apoptotic actions. Abnormally high concentrations of glutamate provoke over-excitation of neurons leading to cell damage and apoptosis. Thus, the aim of this study was to investigate whether the administration of growth hormone-releasing peptide 6 and insulin-like growth factor I attenuates monosodium glutamate-induced apoptosis in RCA-6 neurons and the mechanisms involved. Two different mechanisms are involved in glutamate-induced cell death, one by means of caspase activation and the second through activation of a caspase-independent pathway of apoptosis mediated by the translocation of apoptosis-inducing factor. Growth hormone-releasing peptide 6 partially reversed glutamate-induced cell death but not the activation of caspases, suggesting blockage of the caspase-independent cell death pathway, which included interference with the translocation of apoptosis-inducing factor to the nucleus associated with the induction of Bcl-2. In contrast, the addition of insulin-like growth factor I to RCA-6 neurons abolished glutamate-induced caspase activation and cell death. These data demonstrate for the first time a neuroprotective role for growth hormone secretagogues in the caspase-independent cell death pathway and indicate that these peptides have neuroprotective effects independent of its induction of insulin-like growth factor I. [source]


Differential regulation of NMDA receptor function by DJ-1 and PINK1

AGING CELL, Issue 5 2010
Ning Chang
Summary Dysfunction of PTEN-induced kinase 1 (PINK1) or DJ-1 promotes neuronal death and is implicated in the pathogenesis of Parkinson's disease, but the underlying mechanisms remain unclear. Given the roles of N -methyl- d- aspartate receptor (NMDAr)-mediated neurotoxicity in various brain disorders including cerebral ischemia and neurodegenerative diseases, we investigated the effects of PINK1 and DJ-1 on NMDAr function. Using protein overexpression and knockdown approaches, we showed that PINK1 increased NMDAr-mediated whole-cell currents by enhancing the function of NR2A-containing NMDAr subtype (NR2ACNR). However, DJ-1 decreased NMDAr-mediated currents, which was mediated through the inhibition of both NR2ACNR and NR2B-containing NMDAr subtype (NR2BCNR). We revealed that the knockdown of DJ-1 enhanced PTEN expression, which not only potentiated NR2BCNR function but also increased PINK1 expression that led to NR2ACNR potentiation. These results indicate that NMDAr function is differentially regulated by DJ-1-dependent signal pathways DJ-1/PTEN/NR2BCNR and DJ-1/PTEN/PINK1/NR2ACNR. Our results further showed that the suppression of DJ-1, while promoted NMDA-induced neuronal death through the overactivation of PTEN/NR2BCNR-dependent cell death pathway, induced a neuroprotective effect to counteract DJ-1 dysfunction-mediated neuronal death signaling through activating PTEN/PINK1/NR2ACNR cell survival,promoting pathway. Thus, PINK1 acts with DJ-1 in a common pathway to regulate NMDAr-mediated neuronal death. This study suggests that the DJ-1/PTEN/NR2BCNR and DJ-1/PTEN/PINK1/NR2ACNR pathways may represent potential therapeutic targets for the development of neuroprotection strategy in the treatment of brain injuries and neurodegenerative diseases such as Parkinson's disease. [source]


Genotype-dependent priming to self- and xeno-cannibalism in heterozygous and homozygous lymphoblasts from patients with Huntington's disease

JOURNAL OF NEUROCHEMISTRY, Issue 4 2006
Elisabetta Mormone
Abstract In the present work, we studied the mitochondrial function and cell death pathway(s) in heterozygous and homozygous immortalized cell lines from patients with Huntington's disease (HD). Heterozygosis was characterized by specific alterations in mitochondrial membrane potential, a constitutive hyperpolarization state of mitochondria, and was correlated with an increased susceptibility to apoptosis. Lymphoblasts from homozygous patients, on the other hand, were characterized by a significant percentage of cells displaying autophagic vacuoles. These cells also demonstrated a striking attitude towards significant cannibalistic activity. Considering the pathogenic role of cell death in HD, our study provides new and useful insights into the role of mitochondrial dysfunction, i.e. hyperpolarization, in hijacking HD heterozygous cells towards apoptosis and HD homozygous cells towards a peculiar phenotype characterized by both self- and xeno-cannibalism. These events can, however, be viewed as an ultimate attempt to survive rather than a way to die. The present work underlines the possibility that HD-associated mitochondrial defects could tentatively be by-passed by the cells by activating cellular ,phagic' activities, including so-called ,mitophagy' and ,cannibalism', that only finally lead to cell death. [source]


Overexpression of human copper/zinc-superoxide dismutase in transgenic animals attenuates the reduction of apurinic/apyrimidinic endonuclease expression in neurons after in vitro ischemia and after transient global cerebral ischemia

JOURNAL OF NEUROCHEMISTRY, Issue 2 2005
Purnima Narasimhan
Abstract Oxidative stress after ischemia/reperfusion has been shown to induce DNA damage and subsequent DNA repair activity. Apurinic/apyrimidinic endonuclease (APE) is a multifunctional protein in the DNA base excision repair pathway which repairs apurinic/apyrimidinic sites in DNA. We investigated the involvement of oxidative stress and expression of APE in neurons after oxygen,glucose deprivation and after global cerebral ischemia. Our results suggest that overexpression of human copper/zinc-superoxide dismutase reduced oxidative stress with a subsequent decrease in APE expression. Production of oxygen free radicals and inhibition of the base excision repair pathway may play pivotal roles in the cell death pathway after ischemia. [source]


Activation of caspase-3 alone is insufficient for apoptotic morphological changes in human neuroblastoma cells

JOURNAL OF NEUROCHEMISTRY, Issue 6 2002
Margaret M. Racke
Abstract Activated caspase-3 is considered an important enzyme in the cell death pathway. To study the specific role of caspase-3 activation in neuronal cells, we generated a stable tetracycline-regulated SK-N-MC neuroblastoma cell line, which expressed a highly efficient self-activating chimeric,caspase-3, consisting of the caspase-1 prodomain fused to the caspase-3 catalytic domain. Under expression-inducing conditions, we observed a time-dependent increase of processed caspase-3 by immunostaining for the active form of the enzyme, intracellular caspase-3 enzyme activity, as well as poly(ADP-ribose) polymerase (PARP) cleavage. Induced expression of the caspase fusion protein showed predominantly caspase-3 activity without any apoptotic morphological changes. In contrast, staurosporine treatment of the same cells resulted in activation of multiple caspases and profound apoptotic morphology. Our work provides evidence that auto-activation of caspase-3 can be efficiently achieved with a longer prodomain and that neuronal cell apoptosis may require another caspase or activation of multiple caspase enzymes. [source]


Characterization of the caspase cascade in a cell culture model of SOD1-related familial amyotrophic lateral sclerosis: expression, activation and therapeutic effects of inhibition

NEUROPATHOLOGY & APPLIED NEUROBIOLOGY, Issue 5 2005
S. Sathasivam
There is increasing evidence that apoptosis or a similar programmed cell death pathway is the mechanism of cell death responsible for motor neurone degeneration in amyotrophic lateral sclerosis. Knowledge of the relative importance of different caspases in the cell death process is at present incomplete. In addition, there is little information on the critical point of the death pathway when the process of dying becomes irreversible. In this study, using the well-established NSC34 motor neurone-like cell line stably transfected with empty vector, normal or mutant human Cu-Zn superoxide dismutase (SOD1), we have characterized the activation of the caspase cascade in detail, revealing that the activation of caspases-9, -3 and -8 are important in motor neurone death and that the presence of mutant SOD1 causes increased activation of components of the apoptotic cascade under both basal culture conditions and following oxidative stress induced by serum withdrawal. Activation of the caspases identified in the cellular model has been confirmed in the G93A SOD1 transgenic mice. Furthermore, investigation of the effects of anti-apoptotic neuroprotective agents including specific caspase inhibitors, minocycline and nifedipine, have supported the importance of the mitochondrion-dependent apoptotic pathway in the death process and revealed that the upstream caspase cascade needs to be inhibited if useful neuro-protection is to be achieved. [source]


Apoptosis in amyotrophic lateral sclerosis: a review of the evidence

NEUROPATHOLOGY & APPLIED NEUROBIOLOGY, Issue 4 2001
S. Sathasivam
Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease primarily affecting the upper and lower motor neurones of the central nervous system. Recently, a lot of interest has been generated by the possibility that a mechanism of programmed cell death, termed apoptosis, is responsible for the motor neurone degeneration in this condition. Apoptosis is regulated through a variety of different pathways which interact and eventually lead to controlled cell death. Apart from genetic regulation, factors involved in the control of apoptosis include death receptors, caspases, Bcl-2 family of oncoproteins, inhibitor of apoptosis proteins (IAPs), inhibitors of IAPs, the p53 tumour suppressor protein and apoptosis-related molecules. The first part of this article will give an overview of the current knowledge of apoptosis. In the second part of this review, we will examine in detail the evidence for and against the contribution of apoptosis in motor neurone cell death in ALS, looking at cellular-, animal- and human post-mortem tissue-based models. In a chronic neurodegenerative disease such as ALS, conclusive evidence of apoptosis is likely to be difficult to detect, given the rapidity of the apoptotic cell death process in relation to the relatively slow time course of the disease. Although a complete picture of motor neurone death in ALS has not been fully elucidated, there is good and compelling evidence that a programmed cell death pathway operates in this disorder. The strongest body of evidence supporting this comes from the findings that, in ALS, changes in the levels of members of the Bcl-2 family of oncoproteins results in a predisposition towards apoptosis, there is increased expression or activation of caspases-1 and -3, and the dying motor neurones in human cases exhibit morphological features reminiscent of apoptosis. Further supporting evidence comes from the detection of apoptosis-related molecules and anti-Fas receptor antibodies in human cases of ALS. However, the role of the p53 protein in cell death in ALS is at present unclear. An understanding of the mechanism of programmed cell death in ALS may provide important clues for areas of potential therapeutic intervention for neuroprotection in this devastating condition. [source]


Promotion of PDT Efficacy by a Bcl-2 Antagonist

PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 3 2008
David Kessel
Photodynamic therapy (PDT) directed against the endoplasmic reticulum (ER) is also known to target antiapoptotic Bcl-2 family proteins. This effect is associated with the initiation of both apoptosis, a cell death pathway, and autophagy, an organelle recycling system that can lead to survival or cell death. In this study, we examined the ability of the Bcl-2 antagonist HA14-1 to promote the photodynamic efficacy of PDT directed at the ER. At concentrations that independently caused only a small loss of viability, HA14-1 markedly enhanced the proapoptotic and phototoxic effects of ER photodamage. These results provide additional evidence that the antiapoptotic properties of Bcl-2 constitute an important determinant of photokilling, and demonstrate that synergistic effects can result when PDT is coupled with pharmacologic suppression of Bcl-2 function. [source]


Apigenin drives the production of reactive oxygen species and initiates a mitochondrial mediated cell death pathway in prostate epithelial cells

THE PROSTATE, Issue 2 2005
Colm Morrissey
Abstract BACKGROUND Phytoestrogens may reduce tumorigenesis in prostate cancer. We screened five phytoestrogens for their effect on cell growth and apoptosis in PWR-1E, LNCaP, PC-3, and DU145 prostate epithelial cells in vitro. METHODS We assessed cell number, proliferation, and apoptosis using crystal violet assays, flow cytometric analysis, and TUNEL. Focusing specifically on apigenin we assessed the ability of calpain, serine protease, caspase, estrogen receptor, and ceramide synthase inhibitors to block apigenin induced apoptosis. We also analyzed caspase 3, 7, 8, 9, Bcl-2, Bax, Bid, and cytochrome C by Western analysis, and mitochondrial permeability and reactive oxygen species production by flow cytometry using mitosensorTM and DCFH-DA, respectively. RESULTS Apigenin and silybinin significantly reduced cell number, with apigenin inducing apoptosis in PWR-1E, LNCaP, PC-3, and DU145 cells. The PC-3 and DU145 cells were less susceptible to apigenin induced apoptosis then LNCaP and PWR-1E cells. The induction of apoptosis by apigenin was caspase dependent. Apigenin generated reactive oxygen species, a loss of mitochondrial Bcl-2 expression, mitochondrial permeability, cytochrome C release, and the cleavage of caspase 3, 7, 8, and 9 and the concomitant cleavage of the inhibitor of apoptosis protein, cIAP-2. The overexpression of Bcl-2 in LNCaP B10 cells reduced the apoptotic effects of apigenin. CONCLUSIONS Apigenin induces cell death in prostate epithelial cells using a mitochondrial mediated cell death pathway. Bcl-2 has a role in inhibiting apigenin induced cell death in prostate epithelial cells. © 2004 Wiley-Liss, Inc. [source]


Association between leptin receptor gene polymorphisms and early-onset prostate cancer

BJU INTERNATIONAL, Issue 1 2003
Z. Kote-Jarai
Significant tissue loss is a consistent feature of ureteric obstruction with, most studies showing increased programmed cell death or apoptosis of kidney epithelial cells. The study by Chuang et al. showed that there is also muscular damage during obstruction, specifically of the ureteric myocytes. More importantly they show for the first time that this induction of cell death is associated with the increased expression of cytochrome c and the caspases, key proteins that drive the induction of apoptosis. Admittedly they do not show whether cytochrome c is released from the mitochondria or that the caspases are truly activated, important events in the cell death pathway, but an increase in their expression does indicate their role in this process. Understanding the pathways leading to tissue loss during ureteric obstruction has important implications in the development of novel treatments for this condition. OBJECTIVE To report a case-control study examining the relationship between polymorphisms in the leptin receptor (OBR) gene and the development of young-onset prostate cancer, because epidemiological studies report that prostate cancer risk is associated with animal fat intake, and thus we investigated if this association occurs via this genetic mechanism. PATIENTS, SUBJECTS AND METHODS The Lys109Arg (OBR1) and Gln223Arg (OBR2) polymorphisms in the coding region of OBR were studied in blood DNA from 271 patients with prostate cancer aged < 56 years at diagnosis and 277 geographically matched control subjects. Cases were collected through the Cancer Research UK/British Prostate Group Familial Prostate Cancer Study. Blood DNA was genotyped using the polymerase chain reaction and a restriction enzyme digest. RESULTS There was no statistically significant association between the OBR genotype and prostate cancer risk; men homozygous for 109Arg genotype had a slightly increased risk for prostate cancer, with a relative risk (95% confidence interval) of 1.36 (0.65,2.85), and those homozygous for the 223Arg allele had some reduction in prostate cancer risk, at 0.82 (0.58,1.26), but neither was statistically significant. CONCLUSION This case-control study showed no significant association between leptin receptor gene polymorphisms and the risk of young-onset prostate cancer, suggesting that genetic variations in OBR are unlikely to have a major role in the development of early-onset prostate cancer in the UK. [source]


NV-128, a novel isoflavone derivative, induces caspase-independent cell death through the Akt/mammalian target of rapamycin pathway

CANCER, Issue 14 2009
Ayesha B. Alvero MD
Abstract BACKGROUND: Resistance to apoptosis is 1 of the key events that confer chemoresistance and is mediated by the overexpression of antiapoptotic proteins, which inhibit caspase activation. The objective of this study was to evaluate whether the activation of an alternative, caspase-independent cell death pathway could promote death in chemoresistant ovarian cancer cells. The authors report the characterization of NV-128 as an inducer of cell death through a caspase-independent pathway. METHODS: Primary cultures of epithelial ovarian cancer (EOC) cells were treated with increasing concentration of NV-128, and the concentration that caused 50% growth inhibition (GI50) was determined using a proprietary assay. Apoptotic proteins were characterized by Western blot analyses, assays that measured caspase activity, immunohistochemistry, and flow cytometry. Protein-protein interactions were determined using immunoprecipitation. In vivo activity was measured in a xenograft mice model. RESULTS: NV-128 was able to induce significant cell death in both paclitaxel-resistant and carboplatin-resistant EOC cells with a GI50 between 1 ,g/mL and 5 ,g/mL. Cell death was characterized by chromatin condensation but was caspase-independent. The activated pathway involved the down-regulation of phosphorylated AKT, phosphorylated mammalian target of rapamycin (mTOR), and phosphorylated ribosomal p70 S6 kinase, and the mitochondrial translocation of beclin-1 followed by nuclear translocation of endonuclease G. CONCLUSIONS: The authors characterized a novel compound, NV-128, which inhibits mTOR and promotes caspase-independent cell death. The current results indicated that inhibition of mTOR may represent a relevant pathway for the induction of cell death in cells resistant to the classic caspase-dependent apoptosis. These findings demonstrate the possibility of using therapeutic drugs, such as NV-128, which may have beneficial effects in patients with chemoresistant ovarian cancer. Cancer 2009. © 2009 American Cancer Society. [source]


Streptococcus pyogenes induces oncosis in macrophages through the activation of an inflammatory programmed cell death pathway

CELLULAR MICROBIOLOGY, Issue 1 2009
Oliver Goldmann
Summary Macrophages are crucial components of the host defence against Streptococcus pyogenes. Here, we demonstrate the ability of S. pyogenes to kill macrophages through the activation of an inflammatory programmed cell death pathway. Macrophages exposed to S. pyogenes exhibited extensive cytoplasmic vacuolization, cellular and organelle swelling and rupture of the plasma membrane typical of oncosis. The cytotoxic effect of S. pyogenes on macrophages is mediated by the streptococcal cytolysins streptolysin S and streptolysin O and does not require bacterial internalization. S. pyogenes -induced death of macrophages was not affected by the addition of osmoprotectant, implicating the activation of an orchestrated cell death pathway rather than a simple osmotic lysis. This programme cell death pathway involves the loss of mitochondria transmembrane potential (,,m) and was inhibited by the addition of exogenous glycine, which has been shown to prevent necrotic cell death by blocking the opening of death channels in the plasma membrane. The production of reactive oxygen species and activation of calpains were identified as mediators of the cell death process. We conclude that activation of the inflammatory programmed cell death pathway in macrophages could constitute an important pathogenic mechanism by which S. pyogenes evades host immune defences and causes disease. [source]


Comparative mechanisms of zearalenone and ochratoxin A toxicities on cultured HepG2 cells: Is oxidative stress a common process?

ENVIRONMENTAL TOXICOLOGY, Issue 6 2009
Emna El Golli Bennour
Abstract Zearalenone (ZEN) and Ochratoxin A (OTA) are structurally diverse fungal metabolites that can contaminate feed and foodstuff and can cause serious health problems for animals as well as for humans. In this study, we get further insight of the molecular aspects of ZEN and OTA toxicities in cultured human HepG2 hepatocytes. In this context, we have monitored the effects of ZEN and OTA on (i) cell viability, (ii) heat shock protein (Hsp) 70 and Hsp 27 gene expressions as a parameter of protective and adaptive response, (iii) oxidative damage, and (iv) cell death pathways. Our results clearly showed that both ZEN and OTA inhibit cell proliferation. For ZEN, a significant induction of Hsp 70 and Hsp 27 was observed. In the same conditions, ZEN generated an important amount of reactive oxygen species (ROS). Antioxidant supplements restored the major part of cell mortality induced by ZEN. However, OTA treatment downregulated Hsp 70 and Hsp 27 protein and mRNA levels and did not induce ROS generation. Antioxidant supplements did not have a significant effect on OTA-induced cell mortality. Using another cell system (Vero monkey kidney cells), we demonstrated that OTA downregulates three members of HSP 70 family: Hsp 70, Hsp 75, and Hsp 78. Our findings showed that oxidative damage seemed to be the predominant toxic effect for ZEN, while OTA toxicity seemed to be rather because of the absence of Hsps protective response. Furthermore, the two mycotoxins induced an apoptotic cell death. © 2008 Wiley Periodicals, Inc. Environ Toxicol, 2009. [source]


Yeast Programmed Cell Death: An Intricate Puzzle

IUBMB LIFE, Issue 3 2005
P. Ludovico
Abstract Yeasts as eukaryotic microorganisms with simple, well known and tractable genetics, have long been powerful model systems for studying complex biological phenomena such as the cell cycle or vesicle fusion. Until recently, yeast has been assumed as a cellular 'clean room' to study the interactions and the mechanisms of action of mammalian apoptotic regulators. However, the finding of an endogenous programmed cell death (PCD) process in yeast with an apoptotic phenotype has turned yeast into an 'unclean' but even more powerful model for apoptosis research. Yeast cells appear to possess an endogenous apoptotic machinery including its own regulators and pathway(s). Such machinery may not exactly recapitulate that of mammalian systems but it represents a simple and valuable model which will assist in the future understanding of the complex connections between apoptotic and non-apoptotic mammalian PCD pathways. Following this line of thought and in order to validate and make the most of this promising cell death model, researchers must undoubtedly address the following issues: what are the crucial yeast PCD regulators? How do they play together? What are the cell death pathways shared by yeast and mammalian PCD? Solving these questions is currently the most pressing challenge for yeast cell death researchers.IUBMB Life, 57: 129-135, 2005 [source]


Overexpression of Par-4 enhances thapsigargin-induced apoptosis via down-regulation of XIAP and inactivation of Akt in human renal cancer cells

JOURNAL OF CELLULAR BIOCHEMISTRY, Issue 2 2008
Tae-Jin Lee
Abstract The prostate-apoptosis-response-gene-4 (Par-4) protein has been shown to function as an effector of cell death in response to various apoptotic stimuli that trigger mitochondria and membrane receptor-mediated cell death pathways. We found that overexpressing Par-4 by stable transfection sensitizes Caki cells to induction of apoptosis by TRAIL and drugs that induce endoplasmic reticulum (ER) stress [thapsigargin (TG), tunicamycin (TU) and etoposide]. Ectopic expression of Par-4 is associated with decreased levels of XIAP protein in TG-treated cells, caused in part by XIAP protein instability and caspase activation. Levels of phospho-Akt are decreased in Caki/Par-4 cells to a significantly greater extent than in Caki/Vector cells by treatment with TG, and this is in turn associated with decreased levels of phospho-PDK1, the kinase upstream of Akt. In conclusion, we provide evidence that ectopic expression of Par-4 sensitizes Caki cells to TG and that XIAP protein instability and inactivation of Akt are important in cellular pathways affected by Par-4. J. Cell. Biochem. 103: 358,368, 2008. © 2007 Wiley-Liss, Inc. [source]


Mitochondrial alterations in Parkinson's disease: new clues

JOURNAL OF NEUROCHEMISTRY, Issue 2 2008
Miquel Vila
Abstract Mitochondrial dysfunction has long been associated with Parkinson's disease (PD). In particular, complex I impairment and subsequent oxidative stress have been widely demonstrated in experimental models of PD and in post-mortem PD samples. A recent wave of new studies is providing novel clues to the potential involvement of mitochondria in PD. In particular, (i) mitochondria-dependent programmed cell death pathways have been shown to be critical to PD-related dopaminergic neurodegeneration, (ii) many disease-causing proteins associated with familial forms of PD have been demonstrated to interact either directly or indirectly with mitochondria, (iii) aging-related mitochondrial changes, such as alterations in mitochondrial DNA, are increasingly being associated with PD, and (iv) anomalies in mitochondrial dynamics and intra-neuronal distribution are emerging as critical participants in the pathogenesis of PD. These new findings are revitalizing the field and reinforcing the potential role of mitochondria in the pathogenesis of PD. Whether a primary or secondary event, or part of a multi-factorial pathogenic process, mitochondrial dysfunction remains at the forefront of PD research and holds the promise as a potential molecular target for the development of new therapeutic strategies for this devastating, currently incurable, disease. [source]


Isoform- and subcellular fraction-specific differences in hippocampal 14-3-3 levels following experimentally evoked seizures and in human temporal lobe epilepsy

JOURNAL OF NEUROCHEMISTRY, Issue 2 2006
Clara K. Schindler
Abstract 14-3-3 proteins are a family of signaling molecules involved in diverse cellular functions, which can mediate anti-apoptotic effects. Seizure-induced neuronal death may involve programmed (apoptotic) cell death pathways and is associated with a decline in brain 14-3-3 levels. Presently, we investigated the subcellular localization and effects of seizures on isoforms of 14-3-3 in rat hippocampus, and contrasted these to findings in human temporal lobe epilepsy (TLE). All brain isoforms of 14-3-3 were detected in the cytoplasmic compartment of rat hippocampus, while 14-3-3, and -, were also present in mitochondrial and microsome-enriched fractions. Focally evoked seizures in rats significantly reduced 14-3-3, levels within the microsome-enriched compartment at 4 h, with similar responses for 14-3-3,, while cytoplasm-localized 14-3-3,, -, and -, remained unchanged. Analysis of human autopsy control hippocampus revealed similar 14-3-3 isoform expression profiles. In TLE samples, the microsome-enriched fraction also showed differences, but here 14-3-3, and -, levels were higher than controls. TLE sample 14-3-3 isoform abundance within the cytoplasmic fraction was not different to controls. This study defines the subcellular localization of 14-3-3 isoforms in rat and human hippocampus and identifies the microsome-enriched fraction as the main site of altered 14-3-3 levels in response to acute prolonged and chronic recurrent seizures. [source]


Bioenergetics in the pathogenesis of neurodegeneration

JOURNAL OF NEUROCHEMISTRY, Issue 2001
M. Flint Beal
Evidence implicating both mitochondria and bioenergetics as playing a crucial role in necrotic and apoptotic cell death is rapidly accumulating. Mitochondria are essential in controlling specific apoptosis cell death pathways and they are the major source of free radicals in the cell. Direct evidence for a role of mitochondria in neurodegenerative diseases comes from studies in Friedreich's Ataxia. Mutations in frataxin lead to an accumulation of iron within mitochondria. We found a three-fold increase in a marker of oxidative damage to DNA in the urine of patients with Friedreich's Ataxia. There is evidence for mitochondrial defects in patients with amyotrophic lateral sclerosis (ALS). There are mitochondrial abnormalities in liver biopsies and muscle biopsies from individuals with sporadic ALS. Muscle biopsies have shown reduced complex I activity in patients with sporadic ALS. A study of ALS cybrids showed a significant decrease in complex I activity as well as trends towards reduced complex 3 and 4 activities. We found increased levels of 8-hydroxy-2-deoxyguanosine, a marker of oxidative damage to DNA in the plasma, urine and CSF of sporadic ALS patients and increased numbers of point mutations in mtDNA of ALS spinal cord tissue. There is mitochondrial vacuolization in transgenic mouse models of ALS. We found substantial evidence for mitochondrial dysfunction in Huntington's Disease (HD). In HD postmortem brain tissue, there are significant reductions in complex 2, 3 activity. We also demonstrated increased brain lactate concentrations as well as reduced phosphocreatine to inorganic phosphate ratio in the resting muscle of patients with HD. More recent studies have demonstrated that there is abnormal depolarization of mitochondria of HD lymphoblasts, which directly correlates with CAG repeat length. There are reductions in ATP production in muscle are both presymptomatic and symptomatic HD patients. Transgenic mouse models of HD show significant reductions in N-acetylaspartate concentrations, which precede the onset of neuronal degeneration. We investigated a number of therapeutic interventions in both transgenic mouse models of ALS and HD. In transgenic ALS mice we found that oral administration of creatine dose-dependently extends survival and reduces the neuronal degeneration in the spinal cord. We found modest protection with ginkgo biloba and lipoic acid. In the HD mice we found significant improvement with oral administration of creatine in two different transgenic mouse models. Creatine not only extended survival but it also improved motor performance, delayed weight loss and attenuated striatal atrophy. Creatine significantly attenuated reductions in N-acetylaspartate concentrations as assessed using magnetic resonance spectroscopy. We also found significant neuroprotective effects with dichloroacetate, which stimulates pyruvate dehydrogenase. These findings implicate bioenergetic dysfunction in transgenic mouse models of both ALS and HD, and they suggest several novel therapeutic strategies aimed at energy replenishment. [source]


The flavonoid tangeretin activates the unfolded protein response and synergizes with imatinib in the erythroleukemia cell line K562

MOLECULAR NUTRITION & FOOD RESEARCH (FORMERLY NAHRUNG/FOOD), Issue 6 2010
Sofie Lust
Abstract We explored the mechanism of cell death of the polymethoxyflavone tangeretin (TAN) in K562 breakpoint cluster region-abelson murine leukemia (Bcr-Abl+) cells. Flow cytometric analysis showed that TAN arrested the cells in the G2/M phase and stimulated an accumulation of the cells in the sub-G0 phase. TAN-induced cell death was evidenced by poly(ADP)-ribose polymerase cleavage, DNA laddering fragmentation, activation of the caspase cascade and downregulation of the antiapoptotic proteins Mcl-1 and Bcl-xL. Pretreatment with the pancaspase inhibitor Z-VAD-FMK_blocked caspase activation and cell cycle arrest but did not inhibit apoptosis which suggest that other cell killing mechanisms like endoplasmic reticulum (ER)-associated cell death pathways could be involved. We demonstrated that TAN-induced apoptosis was preceded by a rapid activation of the proapoptotic arm of the unfolded protein response, namely PKR-like ER kinase. This was accompanied by enhanced levels of glucose-regulated protein of 78,kDa and of spliced X-box binding protein 1. Furthermore, TAN sensitized K562 cells to the cell killing effects of imatinib via an apoptotic mechanism. In conclusion, our results suggest that TAN is able to induce apoptosis in Bcr-Abl+ cells via cell cycle arrest and the induction of the unfolded protein response, and has synergistic cytotoxicity with imatinib. [source]


The immunohistochemical expression of BNIP3 protein in non-small-cell lung cancer: a tissue microarray study

APMIS, Issue 8 2010
IVO ÜBERALL
Überall I, Kolek V, Klein J, Krej,í V, ,,astná J, Radová L, ,karda J, Fridman E. The immunohistochemical expression of BNIP3 protein in non-small-cell lung cancer: a tissue microarray study. APMIS 2010; 118: 565,70. Drug resistance is one of the reasons for chemotherapy failure in non-small-cell lung carcinoma (NSCLC). One of the major mechanisms of drug resistance is the inhibition of chemotherapy-induced apoptosis. Therefore, the study of novel cell death pathways could possibly enable us to overcome resistance to apoptosis in NSCLC. One of the non-caspase types of cell death is autophagy. BNIP3 protein, a Bcl-2 family member, highly expressed in some tumours, plays a key role in the induction of autophagy. In the present study, we investigated the immunohistochemical expression and subcellular localization of BNIP3 in a series of early- and late-stage non-small-cell lung carcinomas and normal bronchial tissues, and correlated this expression with the occurrence of metastasis and survival. BNIP3 was strongly expressed in the nucleus of cancer cells in 16/79 (20.3%) cases. This BNIP3 positivity did not correlate with histological grade, stage, histology type, metastatic potential, or expression of BNIP3 according to median values. No significant correlation was observed between the expression of BNIP3 and the overall survival of NSCLC patients (p = 0.55). Nor did we find any significant correlation between BNIP3 expression and the occurrence of site-specific metastasis (p = 0.85). [source]


The mode of action of venom from the endoparasitic wasp Pimpla hypochondriaca (Hymenoptera: Ichneumonidae) involves Ca+2 -dependent cell death pathways,

ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY (ELECTRONIC), Issue 3 2009
David B. Rivers
Abstract The endoparasitoid Pimpla hypochondriaca injects venom during oviposition to condition its lepidopteran hosts. Venom is a complex mixture of proteins and polypeptides, many of which have been identified as enzymes, including phenoloxidase, endopeptidase, aminopeptidase, hydrolase, and angiotensin-converting enzyme. Constituents of the venom have been shown to possess cytolytic and paralytic activity, but the modes of action of factor(s) responsible for exerting such effects have not been deciphered. In this study, we examined the mode of action of isolated venom using cultured cells (BTI-TN-5B1-4). A series of blockage and inhibition assays were performed using a potent inhibitor (phenylthiourea, PTU) of venom phenoloxidase, and anti-calreticulin antibodies. Monolayers exposed to venom alone were highly susceptible with more than 84.6±2.3% dead within 15,min. Susceptible cells displayed a retraction of cytoplasmic extensions, rounding, and swelling prior to lysis in more than half (55.7±1.7%) of the dying cells. Within 15,min of exposure to venom, cells displayed qualitative increases in [Ca+2]i as evidenced by staining with the calcium-sensitive probe fluo-4 AM, and mitochondrial membrane potential (,,m) was undetectable by 5,min post-treatment with venom. These venom-mediated changes occurred regardless of whether an external source of calcium was present, or whether venom was pre-treated with PTU. In contrast, venom toxicity was attenuated by treatment with anti-calreticulin antibodies. Not only did fewer cells die when exposed to antibody-treated venom but also cell swelling diminished and no increases in intracellular calcium were detected. A possible mode of action for the venom is discussed. © 2009 Wiley Periodicals, Inc. [source]


Role of mitochondrial ion channels in cell death

BIOFACTORS, Issue 4 2010
Shin-Young Ryu
Abstract Ion channels located in the outer and inner mitochondrial membranes are key regulators of cellular signaling for life and death. Permeabilization of mitochondrial membranes is one of the most critical steps in the progression of several cell death pathways. The mitochondrial apoptosis-induced channel (MAC) and the mitochondrial permeability transition pore (mPTP) play major roles in these processes. Here, the most recent progress and current perspectives about the roles of MAC and mPTP in mitochondrial membrane permeabilization during cell death are presented. The crosstalk signaling of MAC and mPTP formation/activation mediated by cytosolic Ca2+ signaling, Bcl-2 family proteins, and other mitochondrial ion channels is also discussed. Understanding the mechanisms that regulate opening and closing of MAC and mPTP has revealed new therapeutic targets that potentially could control cell death in pathologies such as cancer, ischemia/reperfusion injuries, and neurodegenerative diseases. [source]


The combination of the antitumoural pyridyl cyanoguanidine CHS 828 and etoposide in vitro,from cytotoxic synergy to complete inhibition of apoptosis

BRITISH JOURNAL OF PHARMACOLOGY, Issue 4 2002
P Martinsson
The present study was aimed at elucidating the apoptosis inhibitory properties of the cyanoguanidine CHS 828. CHS 828 exhibits impressive cytotoxic activity in vitro and in vivo. Apoptosis is not its main mode of cytotoxic effect, and we have previously proposed a dual mechanism, where CHS 828 inhibits its own cell death pathways. Etoposide on the other hand, is a well-established anticancer agent with documented effect in a number of malignancies, induces apoptosis through extensively studied caspase dependent pathways. Here we studied the combined effect of the two drugs in the human lymphoma cell line U-937 GTB. Cytotoxicity was evaluated as total viability measured by the fluorometric microculture cytotoxicity assay (FMCA). Caspase activity was assessed by colorimetric detection of specific cleavage products for caspases 3, 8 and 9, respectively. Morphology was evaluated in May-Grünwald/Giemsa stained preparations. Interaction analysis based on FMCA results of simple combination exposure revealed impressive synergistic effect on cell kill. Detailed investigations of the kinetics involved showed that short pre-exposure (0,12 h) to CHS 828 enhanced caspase activation by etoposide, while longer pre-exposure (18,48 h) inhibited both caspase activation and apoptotic morphology otherwise induced by etoposide. The present results support the theory that CHS 828 block specific cell death pathways. The synergistic results are promising for future combination trials in animals, however, different dosing schedules should be considered, in order to investigate whether the above findings translate into the in vivo setting. British Journal of Pharmacology (2002) 137, 568,573. doi:10.1038/sj.bjp.0704888 [source]