يعرض 1 - 10 نتائج من 16 نتيجة بحث عن '"mitochondrial outer membrane permeabilization"', وقت الاستعلام: 0.77s تنقيح النتائج
  1. 1

    المصدر: Cellular and Molecular Life Sciences

    الوصف: Apoptotic cell death is essential for development, immune function or tissue homeostasis, and its mis-regulation is linked to various diseases. Mitochondrial outer membrane permeabilization (MOMP) is a central event in the intrinsic apoptotic pathway and essential to control the execution of cell death. Here we review current concepts in regulation of MOMP focusing on the interaction network of the Bcl-2 family proteins as well as further regulatory elements influencing MOMP. As MOMP is a complex spatially and temporally controlled process, we point out the importance of single-molecule techniques to unveil processes which would be masked by ensemble measurements. We report key single-molecule studies applied to decipher the composition, assembly mechanism and structure of protein complexes involved in MOMP regulation.

  2. 2

    المساهمون: Universidade do Minho

    المصدر: Repositório Científico de Acesso Aberto de Portugal
    Repositório Científico de Acesso Aberto de Portugal (RCAAP)
    instacron:RCAAP

    الوصف: Endoplasmic reticulum-mitochondria contact sites have been a subject of increasing scientific interest since the discovery that these structures are disrupted in several pathologies. Due to the emerging data that correlate endoplasmic reticulum-mitochondria contact sites function with known events of the apoptotic program, we aimed to dissect this interplay using our well-established model of acetic acid-induced apoptosis in Saccharomyces cerevisiae. Until recently, the only known tethering complex between ER and mitochondria in this organism was the ER-mitochondria encounter structure (ERMES). Following our results from a screening designed to identify genes whose deletion rendered cells with an altered sensitivity to acetic acid, we hypothesized that the ERMES complex could be involved in cell death mediated by this stressor. Herein we demonstrate that single ablation of the ERMES components Mdm10p, Mdm12p and Mdm34p increases the resistance of S. cerevisiae to acetic acid-induced apoptosis, which is associated with a prominent delay in the appearance of several apoptotic markers. Moreover, abrogation of Mdm10p or Mdm34p abolished cytochrome c release from mitochondria. Since these two proteins are embedded in the mitochondrial outer membrane, we propose that the ERMES complex plays a part in cytochrome c release, a key event of the apoptotic cascade. In all, these findings will aid in targeted therapies for diseases where apoptosis is disrupted, as well as assist in the development of acetic acid-resistant strains for industrial processes.
    This work was funded by the strategic program UID/BIA/04050/2013 (POCI-01-0145-FEDER-007569) financed by national funds through Fundação para a Ciência e a Tecnologia (FCT) and by Fundo Europeu de Desenvolvimento Regional (FEDER) through COMPETE 2020 – Programa Operacional Competitividade e Internacionalização (POCI).

    وصف الملف: application/pdf

  3. 3

    المصدر: Cancers
    Volume 12
    Issue 6
    Cancers, Vol 12, Iss 1694, p 1694 (2020)

    الوصف: Background: The evidence that pan-Bcl-2 or Bcl-xL-specific inhibitors prematurely kill virus-infected or RNA/DNA-transfected cells provides rationale for investigating these apoptotic inducers further. We hypothesized that not only invasive RNA or DNA (biological factors) but also DNA/RNA-damaging chemical or physical factors could trigger apoptosis that have been sensitized with pan-Bcl-2 or Bcl-xL-specific agents
    Methods: We tested chemical and physical factors plus Bcl-xL-specific inhibitor A-1155463 in cells of various origins and the small roundworms (C. elegans)
    Results: We show that combination of a A-1155463 along with a DNA-damaging agent, 4-nitroquinoline-1-oxide (4NQO), prematurely kills cells of various origins as well as C. elegans. The synergistic effect is p53-dependent and associated with the release of Bad and Bax from Bcl-xL, which trigger mitochondrial outer membrane permeabilization. Furthermore, we found that combining Bcl-xL-specific inhibitors with various chemical compounds or physical insults also induced cell death
    Conclusions: Thus, we were able to identify several biological, chemical and physical triggers of the evolutionarily conserved Bcl-xL-mediated apoptotic pathway, shedding light on strategies and targets for novel drug development.

    وصف الملف: application/pdf

  4. 4

    المصدر: Developmental Cell. 53:619-620

    الوصف: Mitochondrial outer membrane permeabilization (MOMP) is a crucial event enabling apoptotic cell death. In this issue of Developmental Cell, Wang et al. reveal an interaction contributing to full MOMP execution, which depends on endosomes accumulating on apoptotic mitochondria. This causes mitochondrial lipid alterations that may contribute to functional pore assembly.

  5. 5

    المصدر: eLife
    eLife, Vol 9 (2020)

    الوصف: The Bcl-2 family BH3 protein Bim promotes apoptosis at mitochondria by activating the pore forming proteins Bax and Bak and by inhibiting the anti-apoptotic proteins Bcl-XL, Bcl-2 and Mcl-1. Bim binds to these proteins via its BH3 domain and to the mitochondrial membrane by a carboxyl-terminal sequence (CTS). In cells killed by Bim, the expression of a Bim mutant in which the CTS was deleted (BimL-dCTS) triggered variable amounts of apoptosis that correlated with inhibition of anti-apoptotic proteins being sufficient to permeabilize mitochondria isolated from the same cells. Detailed analysis of the molecular mechanism demonstrated that BimL-dCTS inhibited Bcl-XL but did not activate Bax. Our examination of additional point mutants unexpectedly revealed that the CTS of Bim is required for physiological concentrations of Bim to activate Bax and that different residues in the CTS enable Bax activation and binding to membranes.

  6. 6

    المؤلفون: Geetika Singh, Tudor Moldoveanu

    المصدر: Methods in Molecular Biology ISBN: 9781493988600

    الوصف: Mitochondrial outer membrane permeabilization (MOMP) is a crucial initiating event in apoptosis that activates the caspase cascade to execute cell demise. The effector B-cell lymphoma 2 (BCL-2) antagonist killer (BAK) forms mitochondrial apoptotic pores to mediate MOMP. In healthy cells, BAK resides at the outer mitochondrial membrane as a dormant monomer. Upon direct interactions with the BCL-2 homology 3 (BH3)-only proapoptotic proteins during apoptosis, BAK undergoes conformational changes to form the active species associated with apoptotic pores. We describe methods to purify mitochondria for MOMP assays and to detect conformational changes in native BAK associated with MOMP by using limited proteolysis and cross-linking analyses.

  7. 7

    المصدر: Methods in Molecular Biology ISBN: 9781493988600

    الوصف: The proteins of the Bcl-2 family regulate apoptosis by forming a complex interaction network whose output determines whether mitochondrial outer membrane permeabilization is executed. Quantification of complex formation between Bcl-2 proteins in solution and in membranes is therefore key to understand how the hierarchy of interactions controls cell death induction. Fluorescence correlation spectroscopy (FCS) is a noninvasive, nondestructive method to investigate the mobility and the association of fluorescently labeled biomolecules that has provided useful insight into the binding affinity of the Bcl-2 interactome. FCS is based on the detection of fluorescence fluctuations caused by the diffusion of individual molecules through a very tiny observation volume of the detection system. Scanning FCS (SFCS) solves some of the practical challenges of acquiring FCS in membranes and expands the application scope of the method. In this chapter, we explain the principle of FCS and describe protocols how it can be used to quantify interactions between Bcl-2 proteins in solution and in model membrane systems.

  8. 8

    المؤلفون: Claire Thornton, Henrik Hagberg

    المصدر: Clinica Chimica Acta; International Journal of Clinical Chemistry

    الوصف: Hypoxic–ischemic encephalopathy induces secondary brain injury characterized by delayed energy failure. Currently, therapeutic hypothermia is the sole treatment available after severe intrapartum asphyxia in babies and acts to attenuate secondary loss of high energy phosphates improving both short- and long-term outcome. In order to develop the next generation of neuroprotective therapies, we urgently need to understand the underlying molecular mechanisms leading to cell death. Hypoxia–ischemia creates a toxic intracellular environment including accumulation of reactive oxygen/nitrosative species and intracellular calcium after the insult, inducing mitochondrial impairment. More specifically mitochondrial respiration is suppressed and calcium signaling is dysregulated. At a certain threshold, Bax-dependent mitochondrial permeabilization will occur leading to activation of caspase-dependent and apoptosis-inducing factor-dependent apoptotic cell death. In addition, hypoxia–ischemia induces inflammation, which leads to the release of TNF-α, TRAIL, TWEAK, FasL and Toll-like receptor agonists that will activate death receptors on neurons and oligodendroglia. Death receptors trigger apoptotic death via caspase-8 and necroptotic cell death through formation of the necrosome (composed of RIP1, RIP3 and MLKL), both of which converge at the mitochondria.
    Highlights • Hypoxic-ischemic encephalopathy induces secondary brain injury characterized by delayed energy failure and excitotoxicity. • Hypoxia-ischemia triggers accumulation of reactive oxygen species andintracellular calcium, which induces mitochondrial dysfunction. • Mitochondrial impairment can cause Bax-dependent mitochondrial permeabilization, which triggers release of pro-apoptotic proteins and cell death. • During the recovery phase, Inflammation is produced leading to death receptor activation and induction of necroptosis.

  9. 9

    المصدر: Autophagy

    مصطلحات موضوعية: endoplasmic-reticulum stress, Fas-Associated Death Domain Protein, GAPDH, glyceraldehyde 3-phosphate dehydrogenase, ATG, autophagy related, chain, DDIT3, DNA-damage-inducible transcript 3, Endoplasmic Reticulum, Autophagy-Related Protein 7, caspase-8, Autophagy-Related Protein 5, cytochrome-c, FADD, Fas (TNFRSF6)-associated via death domain, Mice, 0302 clinical medicine, HSPA5, heat shock 70 kDa protein 5 (glucose-regulated protein, 78 kDa), MOMP, mitochondrial outer membrane permeabilization, FADD, Endoplasmic Reticulum Chaperone BiP, Caspase, TNF, tumor necrosis factor, Caspase 8, 0303 health sciences, biology, Caspase 3, MEFs, mouse embryonic fibroblasts, BCL2, B-cell CLL/lymphoma 2, apoptosis, BAK1, BCL2-antagonist/killer 1, unfolded protein response, Caspase 9, Mitochondria, Cell biology, BAX, BCL2-associated X protein, autophagic cell death, 030220 oncology & carcinogenesis, endoplasmic reticulum stress, Tm, tunicamycin, roles, Microtubule-Associated Proteins, PARP, poly (ADP-ribose) polymerase, Signal Transduction, DISC, death inducing signaling complex, autophagy, Programmed cell death, Basic Research Papers, assays, caspase, fadd, ATG5, PBS, phosphate-buffered saline, ER, endoplasmic reticulum, PI, propidium iodide, 03 medical and health sciences, Animals, Humans, Molecular Biology, 030304 developmental biology, Bcl-2 family, Cell Biology, Fibroblasts, cell-death, Enzyme Activation, MAP1LC3 (LC3), microtubule-associated protein 1 light chain 3, HEK293 Cells, Gene Expression Regulation, DTT, dithiothreitol, TNFSF10, tumor necrosis factor (ligand) superfamily, member 10, Tg, thapsigargin, biology.protein, activation, bcl-2 family

    الوصف: Endoplasmic reticulum (ER) stress-induced cell death is normally associated with activation of the mitochondrial apoptotic pathway, which is characterized by CYCS (cytochrome c, somatic) release, apoptosome formation, and caspase activation, resulting in cell death. In this study, we demonstrate that under conditions of ER stress cells devoid of CASP9/caspase-9 or BAX and BAK1, and therefore defective in the mitochondrial apoptotic pathway, still undergo a delayed form of cell death associated with the activation of caspases, therefore revealing the existence of an alternative stress-induced caspase activation pathway. We identified CASP8/caspase-8 as the apical protease in this caspase cascade, and found that knockdown of either of the key autophagic genes, ATG5 or ATG7, impacted on CASP8 activation and cell death induction, highlighting the crucial role of autophagy in the activation of this novel ER stress-induced death pathway. In line with this, we identified a protein complex composed of ATG5, FADD, and pro-CASP8 whose assembly coincides with caspase activation and cell death induction. Together, our results reveal the toxic potential of autophagy in cells undergoing ER stress that are defective in the mitochondrial apoptotic pathway, and suggest a model in which the autophagosome functions as a platform facilitating pro-CASP8 activation. Chemoresistance, a common problem in the treatment of cancer, is frequently caused by the downregulation of key mitochondrial death effector proteins. Alternate stress-induced apoptotic pathways, such as the one described here, may become of particular relevance for tackling the problem of chemoresistance in cancer cells.

  10. 10

    المصدر: Repositorio Abierto de la UdL
    Universitad de Lleida
    Recercat. Dipósit de la Recerca de Catalunya
    instname

    الوصف: Autophagy is generally regarded as a mechanism to promote cell survival. However, autophagy can occasionally be the mechanism responsible of cell demise. We have found that a concomitant depletion of glucose, nutrients and growth factors provoked cell death in a variety of cell lines. This death process was contingent upon caspase activation and was mediated by BAX/BAK proteins, thus indicating its apoptotic nature and the engagement of an intrinsic pathway. In order to abrogate autophagy, 3-methyladenine (3-MA), BECLIN-1 siRNA and Atg5 knock-out (Tet-Off type) approaches were alternatively employed. Irrespective of the procedure, at short times of starvation, we found that the ongoing autophagy was sensitizing cells to the permeabilization of the mitochondrial outer membrane (MOMP), caspase activation and, therefore, apoptosis. On the contrary, at longer times of starvation, autophagy displayed its characteristic pro-survival effect on cells. As far as we know, we provide the first experimental paradigm where time is the only variable determining the final outcome of autophagy. In other words, we have circumscribed in time the shift transforming autophagy from a cell death to a protection mechanism. Moreover, at short times, starvation-driven autophagy exacerbated the apoptotic cell death caused by several antitumor agents. In agreement with this fact, their apoptotic effects were greatly diminished by autophagy inhibition. The implications of these facts in tumor biology will be discussed. The author’s thanks Dr. P. Codogno for the Atg5 Tet-Off MEFs m5-7 (originated at Prof. Mizushima’s laboratory) and Dr. S.E. Lupold for the PC3 and DU145 cell lines. This work was supported by Ministerio de Economía y Competitividad SAF2011-29730. VJY is under a “Retention of Research Talent” contract of “Programa Banco de Santander”. PM was supported by a fellowship (AH9815758) from AGAUR (Generalitat de Catalunya). University of Lleida Funds (Ajuts Pont 2015) contributed to the completion of this work.

    وصف الملف: application/pdf