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1
Zweck, Elric, Julia Szendrödi, Malte Kelm, and Michael Roden. "Das diabetische Herz und Herzinsuffizienz – Aktuelles zu Entstehung und Therapie." DMW - Deutsche Medizinische Wochenschrift 144, no. 03 (January 31, 2019): 175–79. http://dx.doi.org/10.1055/a-0646-7871.
Анотація:
Was ist neu? Klinisches Bild Typ-2-Diabetes-mellitus (T2 D) ist ein unabhängiger Risikofaktor für Herzinsuffizienz, die als Komplikation oftmals unterschätzt wird. Bei T2 D kann sich früh eine diastolische Funktionsstörung ausbilden, die sich später zu einer Herzinsuffizienz entwickeln kann. Von einer ischämischen Kardiomyopathie ist eine Diabetes-bedingte Herzinsuffizienz aktuell nicht abgrenzbar. Pathophysiologie Hyperglykämie, Hyperinsulinämie und Hyperlipidämie bei T2 D verändern den myokardialen Stoffwechsel. Daraus resultieren oxidativer Stress, reduzierte mitochondriale Effizienz, Lipotoxizität und Apoptose im Herzen. Die T2D-assoziierte nicht-alkoholische Fettlebererkrankung (NAFLD) zeigt ähnliche Pathomechanismen und stellt einen potenziellen Risikofaktor dar. Therapiestrategien Zur Verbesserung der Herzfunktion wird die Kontrolle kardiovaskulärer Risikofaktoren sowie Reduktion der Insulinresistenz durch Bewegung und Gewichtsabnahme empfohlen. Neben Metformin scheinen SGLT2-Inhibitoren als zusätzliche Therapieoption besonders geeignet zu sein. Auch die NAFLD könnte ein Angriffspunkt zukünftiger Therapieansätze werden.
2
Adhihetty, Peter J., Vladimir Ljubicic, and David A. Hood. "Effect of chronic contractile activity on SS and IMF mitochondrial apoptotic susceptibility in skeletal muscle." American Journal of Physiology-Endocrinology and Metabolism 292, no. 3 (March 2007): E748—E755. http://dx.doi.org/10.1152/ajpendo.00311.2006.
Анотація:
Chronic contractile activity of skeletal muscle induces an increase in mitochondria located in proximity to the sarcolemma [subsarcolemmal (SS)] and in mitochondria interspersed between the myofibrils [intermyofibrillar (IMF)]. These are energetically favorable metabolic adaptations, but because mitochondria are also involved in apoptosis, we investigated the effect of chronic contractile activity on mitochondrially mediated apoptotic signaling in muscle. We hypothesized that chronic contractile activity would provide protection against mitochondrially mediated apoptosis despite an elevation in the expression of proapoptotic proteins. To induce mitochondrial biogenesis, we chronically stimulated (10 Hz; 3 h/day) rat muscle for 7 days. Chronic contractile activity did not alter the Bax/Bcl-2 ratio, an index of apoptotic susceptibility, and did not affect manganese superoxide dismutase levels. However, contractile activity increased antiapoptotic 70-kDa heat shock protein and apoptosis repressor with a caspase recruitment domain by 1.3- and 1.4-fold ( P < 0.05), respectively. Contractile activity elevated SS mitochondrial reactive oxygen species (ROS) production 1.4- and 1.9-fold ( P < 0.05) during states IV and III respiration, respectively, whereas IMF mitochondrial state IV ROS production was suppressed by 28% ( P < 0.05) and was unaffected during state III respiration. Following stimulation, exogenous ROS treatment produced less cytochrome c release (25–40%) from SS and IMF mitochondria, and also reduced apoptosis-inducing factor release (≈30%) from IMF mitochondria, despite higher inherent cytochrome c and apoptosis-inducing factor expression. Chronic contractile activity did not alter mitochondrial permeability transition pore (mtPTP) components in either subfraction. However, SS mitochondria exhibited a significant increase in the time to Vmax of mtPTP opening. Thus, chronic contractile activity induces predominantly antiapoptotic adaptations in both mitochondrial subfractions. Our data suggest the possibility that chronic contractile activity can exert a protective effect on mitochondrially mediated apoptosis in muscle.
3
Wissel, Kirsten, Elisabeth Berger, Gudrun Brandes, Gerrit Paasche, Thomas Lenarz, and Martin Durisin. "Erratum: Wie beeinflussen Platin-Nanopartikel die Zellviabilität der Corti-Organ Zelllinie der Maus (HEI-OC1) und der Spiralganglienzellen postnataler Ratten in Kultur?" Laryngo-Rhino-Otologie 101, S 02 (May 2022): e1-e2. http://dx.doi.org/10.1055/a-2004-8821.
Анотація:
Einleitung Systemische Kortison- und Antibiotikagabe können bei einem geringen Prozentsatz der CI-Träger die erhöhten Impedanzen nicht normalisieren. In Studien werden erodierte Platinelektrodenkontakte als mögliche Ursache genannt. Ziel dieser Studie ist die Charakterisierung der Effekte von Platin-Nanopartikeln (Pt-NP, 3 nm) auf die HEI-OC1-Zellen und Spiralganglionneuronen (SGN) in der Zellkultur. Methoden Die metabolische Aktivität mittels Resazurin wurde in den HEI-OC1-Zellen mit 50–150 µg/ml Pt-NP ermittelt. Die Überlebensrate und das Neuritenwachstum der SGN, dissoziiert aus den postnatalen Ratten (P5) und kultiviert für 48 h, wurde nach Gabe der Pt-NP (20–100 µg/ml) mittels Färbung der Neurofilament-Antigene quantitativ bestimmt. Mittels Raster- (REM) und Transmissionselektronenmikroskopie (TEM) wurden Veränderungen der Morphologie und der Ultrastrukturen der Zellen analysiert. Ergebnisse Pt-NP zwischen 75 und 150 µg/ml reduzierten die metabolische Aktivität der HEI-OC1-Zellen, ohne jedoch zytotoxisch zu wirken. REM und TEM zeigten, dass 100 µg/ml Pt-NP nicht nur die Apoptose, sondern auch Reparaturvorgänge mitels des autophagosomal-lysosomalen Systems induzierten. Bei keiner Pt-NP-Konzentration wurde ein SGN-Verlust oder eine Reduktion des Neuritenwachstums gefunden. Schlußfolgerungen Pt-NP reduzierten in Konzentrationen ab 75 µg/ml die mitochondriale Aktivität in den HEI-OC1-Zellen, induzierten jedoch nicht den Zelltod. TEM weist dagegen auf effektive Reparaturmechanismen hin. Im Vergleich dazu führten Pt-NP zu keiner direkten Beeinträchtigung des SGN-Stoffwechsels. Es ist zu untersuchen, ob eine Exposition der SGN und Gliazellen mit PT-NP über eine längere Kultivierungsdauer zur Schädigung des Stoffwechsels der Neuronen führt.
4
Breckenridge, David G., Marina Stojanovic, Richard C. Marcellus, and Gordon C. Shore. "Caspase cleavage product of BAP31 induces mitochondrial fission through endoplasmic reticulum calcium signals, enhancing cytochrome c release to the cytosol." Journal of Cell Biology 160, no. 7 (March 31, 2003): 1115–27. http://dx.doi.org/10.1083/jcb.200212059.
Анотація:
Stimulation of cell surface death receptors activates caspase-8, which targets a limited number of substrates including BAP31, an integral membrane protein of the endoplasmic reticulum (ER). Recently, we reported that a caspase-resistant BAP31 mutant inhibited several features of Fas-induced apoptosis, including the release of cytochrome c (cyt.c) from mitochondria (Nguyen, M., D.G. Breckenridge, A. Ducret, and G.C. Shore. 2000. Mol. Cell. Biol. 20:6731–6740), implicating ER-mitochondria crosstalk in this pathway. Here, we report that the p20 caspase cleavage fragment of BAP31 can direct pro-apoptotic signals between the ER and mitochondria. Adenoviral expression of p20 caused an early release of Ca2+ from the ER, concomitant uptake of Ca2+ into mitochondria, and mitochondrial recruitment of Drp1, a dynamin-related protein that mediates scission of the outer mitochondrial membrane, resulting in dramatic fragmentation and fission of the mitochondrial network. Inhibition of Drp1 or ER-mitochondrial Ca2+ signaling prevented p20-induced fission of mitochondria. p20 strongly sensitized mitochondria to caspase-8–induced cyt.c release, whereas prolonged expression of p20 on its own ultimately induced caspase activation and apoptosis through the mitochondrial apoptosome stress pathway. Therefore, caspase-8 cleavage of BAP31 at the ER stimulates Ca2+-dependent mitochondrial fission, enhancing the release of cyt.c in response to this initiator caspase.
5
Basu, Urmimala, Alicia M. Bostwick, Kalyan Das, Kristin E. Dittenhafer-Reed, and Smita S. Patel. "Structure, mechanism, and regulation of mitochondrial DNA transcription initiation." Journal of Biological Chemistry 295, no. 52 (October 30, 2020): 18406–25. http://dx.doi.org/10.1074/jbc.rev120.011202.
Анотація:
Mitochondria are specialized compartments that produce requisite ATP to fuel cellular functions and serve as centers of metabolite processing, cellular signaling, and apoptosis. To accomplish these roles, mitochondria rely on the genetic information in their small genome (mitochondrial DNA) and the nucleus. A growing appreciation for mitochondria's role in a myriad of human diseases, including inherited genetic disorders, degenerative diseases, inflammation, and cancer, has fueled the study of biochemical mechanisms that control mitochondrial function. The mitochondrial transcriptional machinery is different from nuclear machinery. The in vitro re-constituted transcriptional complexes of Saccharomyces cerevisiae (yeast) and humans, aided with high-resolution structures and biochemical characterizations, have provided a deeper understanding of the mechanism and regulation of mitochondrial DNA transcription. In this review, we will discuss recent advances in the structure and mechanism of mitochondrial transcription initiation. We will follow up with recent discoveries and formative findings regarding the regulatory events that control mitochondrial DNA transcription, focusing on those involved in cross-talk between the mitochondria and nucleus.
6
Kokkinopoulou, Ioanna, and Paraskevi Moutsatsou. "Mitochondrial Glucocorticoid Receptors and Their Actions." International Journal of Molecular Sciences 22, no. 11 (June 3, 2021): 6054. http://dx.doi.org/10.3390/ijms22116054.
Анотація:
Mitochondria are membrane organelles present in almost all eukaryotic cells. In addition to their well-known role in energy production, mitochondria regulate central cellular processes, including calcium homeostasis, Reactive Oxygen Species (ROS) generation, cell death, thermogenesis, and biosynthesis of lipids, nucleic acids, and steroid hormones. Glucocorticoids (GCs) regulate the mitochondrially encoded oxidative phosphorylation gene expression and mitochondrial energy metabolism. The identification of Glucocorticoid Response Elements (GREs) in mitochondrial sequences and the detection of Glucocorticoid Receptor (GR) in mitochondria of different cell types gave support to hypothesis that mitochondrial GR directly regulates mitochondrial gene expression. Numerous studies have revealed changes in mitochondrial gene expression alongside with GR import/export in mitochondria, confirming the direct effects of GCs on mitochondrial genome. Further evidence has made clear that mitochondrial GR is involved in mitochondrial function and apoptosis-mediated processes, through interacting or altering the distribution of Bcl2 family members. Even though its exact translocation mechanisms remain unknown, data have shown that GR chaperones (Hsp70/90, Bag-1, FKBP51), the anti-apoptotic protein Bcl-2, the HDAC6- mediated deacetylation and the outer mitochondrial translocation complexes (Tom complexes) co-ordinate GR mitochondrial trafficking. A role of mitochondrial GR in stress and depression as well as in lung and hepatic inflammation has also been demonstrated.
7
Kim, Sin Ri, Ji Won Park, You-Jin Choi, Seong Keun Sonn, Goo Taeg Oh, Byung-Hoon Lee, and Tong-Shin Chang. "Mitochondrial H2O2 Is a Central Mediator of Diclofenac-Induced Hepatocellular Injury." Antioxidants 13, no. 1 (December 21, 2023): 17. http://dx.doi.org/10.3390/antiox13010017.
Анотація:
Nonsteroidal anti-inflammatory drug (NSAID) use is associated with adverse consequences, including hepatic injury. The detrimental hepatotoxicity of diclofenac, a widely used NSAID, is primarily connected to oxidative damage in mitochondria, which are the primary source of reactive oxygen species (ROS). The primary ROS responsible for inducing diclofenac-related hepatocellular toxicity and the principal antioxidant that mitigates these ROS remain unknown. Peroxiredoxin III (PrxIII) is the most abundant and potent H2O2-eliminating enzyme in the mitochondria of mammalian cells. Here, we investigated the role of mitochondrial H2O2 and the protective function of PrxIII in diclofenac-induced mitochondrial dysfunction and apoptosis in hepatocytes. Mitochondrial H2O2 levels were differentiated from other types of ROS using a fluorescent H2O2 indicator. Upon diclofenac treatment, PrxIII-knockdown HepG2 human hepatoma cells showed higher levels of mitochondrial H2O2 than PrxIII-expressing controls. PrxIII-depleted cells exhibited higher mitochondrial dysfunction as measured by a lower oxygen consumption rate, loss of mitochondrial membrane potential, cardiolipin oxidation, and caspase activation, and were more sensitive to apoptosis. Ectopic expression of mitochondrially targeted catalase in PrxIII-knockdown HepG2 cells or in primary hepatocytes derived from PrxIII-knockout mice suppressed the diclofenac-induced accumulation of mitochondrial H2O2 and decreased apoptosis. Thus, we demonstrated that mitochondrial H2O2 is a key mediator of diclofenac-induced hepatocellular damage driven by mitochondrial dysfunction and apoptosis. We showed that PrxIII loss results in the critical accumulation of mitochondrial H2O2 and increases the harmful effects of diclofenac. PrxIII or other antioxidants targeting mitochondrial H2O2 could be explored as potential therapeutic agents to protect against the hepatotoxicity associated with NSAID use.
8
Heikaus, Sebastian, Linda van den Berg, Tobias Kempf, Csaba Mahotka, Helmut Erich Gabbert, and Uwe Ramp. "HA14-1 is Able to Reconstitute the Impaired Mitochondrial Pathway of Apoptosis in Renal Cell Carcinoma Cell Lines." Analytical Cellular Pathology 30, no. 5 (January 1, 2008): 419–33. http://dx.doi.org/10.1155/2008/693095.
Анотація:
Renal cell carcinomas (RCCs) exhibit a marked resistance towards apoptosis. Although most apoptotic stimuli converge at the level of the mitochondria, little is known about the mitochondrial apoptosis pathway in renal cell carcinomas. The aim of the present study, therefore, was to investigate the functionality of the mitochondrial apoptosis pathway in renal cell carcinoma cell lines by exposure to TRAIL, etoposide, HA14-1 and betulinic acid activating the mitochondria by different mechanisms. Sensitivity to TRAIL-induced apoptosis correlated with cleavage of the initiator caspase-8, but the mitochondrial apoptosis pathway was not induced. Similarly, etoposide and betulinic acid could not induce mitochondrial damage. In contrast, HA14-1 was able to activate mitochondrial apoptosis, thereby demonstrating functionally inducible signalling pathways downstream of the mitochondria. The intactness of the pathways upstream of the mitochondria was shown by pretreatment of TRAIL-sensitive cell lines with HA14-1, which could reconstitute TRAIL-induced mitochondrial damage and resulted in a synergistic apoptosis induction.Our results demonstrate that the apoptotic pathways upstream and downstream of the mitochondria are intact and inducible in renal cell carcinoma cell lines. However, resistance towards mitochondrial apoptosis is located on the level of the mitochondria themselves.
9
Peterson, Courtney M., Darcy L. Johannsen, and Eric Ravussin. "Skeletal Muscle Mitochondria and Aging: A Review." Journal of Aging Research 2012 (2012): 1–20. http://dx.doi.org/10.1155/2012/194821.
Анотація:
Aging is characterized by a progressive loss of muscle mass and muscle strength. Declines in skeletal muscle mitochondria are thought to play a primary role in this process. Mitochondria are the major producers of reactive oxygen species, which damage DNA, proteins, and lipids if not rapidly quenched. Animal and human studies typically show that skeletal muscle mitochondria are altered with aging, including increased mutations in mitochondrial DNA, decreased activity of some mitochondrial enzymes, altered respiration with reduced maximal capacity at least in sedentary individuals, and reduced total mitochondrial content with increased morphological changes. However, there has been much controversy over measurements of mitochondrial energy production, which may largely be explained by differences in approach and by whether physical activity is controlled for. These changes may in turn alter mitochondrial dynamics, such as fusion and fission rates, and mitochondrially induced apoptosis, which may also lead to net muscle fiber loss and age-related sarcopenia. Fortunately, strategies such as exercise and caloric restriction that reduce oxidative damage also improve mitochondrial function. While these strategies may not completely prevent the primary effects of aging, they may help to attenuate the rate of decline.
10
Kroemer, Guido. "Heat Shock Protein 70 Neutralizes Apoptosis-Inducing Factor." Scientific World JOURNAL 1 (2001): 590–92. http://dx.doi.org/10.1100/tsw.2001.322.
Анотація:
Programmed cell death (apoptosis) is the physiological process responsible for the demise of superfluous, aged, damaged, mutated, and ectopic cells. Its normal function is essential both for embryonic development and for maintenance of adult tissue homeostasis. Deficient apoptosis participates in cancerogenesis, whereas excessive apoptosis leads to unwarranted cell loss accounting for disparate diseases including neurodegeneration and AIDS. One critical step in the process of apoptosis consists in the permeabilization of mitochondrial membranes, leading to the release of proteins which normally are secluded behind the outer mitochondrial membrane[1]. For example, cytochrome c, which is normally confined to the mitochondrial intermembrane space, is liberated from mitochondria and interacts with a cytosolic protein, Apaf-1, causing its oligomerization and constitution of the so-called apoptosome, a protein complex which activates a specific class of cysteine proteases, the caspases[2]. Another example concerns the so-called apoptosis-inducing factor (AIF), another mitochondrial intermembrane protein which can translocate to the nucleus where it induces chromatin condensation and DNA fragmentation[3].
11
Brooks, Craig, Sung-Gyu Cho, Cong-Yi Wang, Tianxin Yang, and Zheng Dong. "Fragmented mitochondria are sensitized to Bax insertion and activation during apoptosis." American Journal of Physiology-Cell Physiology 300, no. 3 (March 2011): C447—C455. http://dx.doi.org/10.1152/ajpcell.00402.2010.
Анотація:
Recent studies have shown mitochondrial fragmentation during cell stress and have suggested a role for the morphological change in mitochondrial injury and ensuing apoptosis. However, the underlying mechanism remains elusive. Here we demonstrate that mitochondrial fragmentation facilitates Bax insertion and activation in mitochondria, resulting in the release of apoptogenic factors. In HeLa cells, overexpression of mitofusins attenuated mitochondrial fragmentation during cisplatin- and azide-induced cell injury, which was accompanied by less apoptosis and less cytochrome c release from mitochondria. Similar effects were shown by inhibiting the mitochondrial fission protein Drp1 with a dominant negative mutant (dn-Drp1). Mitofusins and dn-Drp1 did not seem to significantly affect Bax translocation/accumulation to mitochondria; however, they blocked Bax insertion and activation in mitochondrial membrane. Consistently, in rat kidney proximal tubular cells, small interfering RNA knockdown of Drp1 prevented mitochondrial fragmentation during azide-induced ATP depletion, which was accompanied by less Bax activation, insertion, and oligomerization in mitochondria. These cells released less cytochrome c and AIF from mitochondria and showed significantly lower apoptosis. Finally, mitofusin-null mouse embryonic fibroblasts (MEF) had fragmented mitochondria. These MEFs were more sensitive to cisplatin-induced Bax activation, release of cytochrome c, and apoptosis. Together, this study provides further support for a role of mitochondrial fragmentation in mitochondrial injury and apoptosis. Mechanistically, mitochondrial fragmentation may sensitize the cells to Bax insertion and activation in mitochondria, facilitating the release of apoptogenic factors and consequent apoptosis.
12
Minamikawa, T., A. Sriratana, D. A. Williams, D. N. Bowser, J. S. Hill, and P. Nagley. "Chloromethyl-X-rosamine (MitoTracker Red) photosensitises mitochondria and induces apoptosis in intact human cells." Journal of Cell Science 112, no. 14 (July 15, 1999): 2419–30. http://dx.doi.org/10.1242/jcs.112.14.2419.
Анотація:
We report that chloromethyl-X-rosamine (MitoTracker Red), a mitochondrion-selective fluorescent probe, has a strong photosensitising action. Photoirradiation of intact cells loaded with chloromethyl-X-rosamine induces depolarisation of the inner mitochondrial membrane and swelling of mitochondria, subsequently resulting in apoptosis. We have studied human osteosarcoma 143B TK-(rho+) cells and the derived (rho)0 206 cell line devoid of mitochondrial DNA. Colony formation tests revealed that chloromethyl-X-rosamine itself has no toxicity to either cell line in the concentration range 100–250 nM (unless photoirradiated). Chloromethyl-X-rosamine has potent phototoxicity such that almost quantitative cell killing was achieved at light doses of >2 J/cm2. These photodamaged cells initially showed swollen degenerative mitochondria and, later, uptake of propidium iodide in their apoptotic nuclei was observed. When cells were loaded with chloromethyl-X-rosamine (100 nM) and imaged by laser scanning confocal microscopy, photoirradiation by the laser beam under routine scanning conditions was sufficient to induce mitochondrial damage in both cell lines. This was evidenced by a rapid decrease of fluorescence intensity of co-loaded rhodamine 123 (indicative of mitochondrial depolarisation). Globular swelling of mitochondria took place within 15 minutes, imaged by the residual fluorescence of chloromethyl-X-rosamine itself, which also markedly decreased in intensity after imaging. Mitochondrial membrane depolarisation of cells loaded with chloromethyl-X-rosamine after photoirradiation using a measured dose of visible light was independently confirmed in 143B TK- and (rho)0 206 cells, by the significant decrease in uptake into cells of [3H]methyltriphenylphosphonium ions. Photoactivation of chloromethyl-X-rosamine in 143B TK-(rho+) cells, whose mitochondria had previously been loaded with calcein, caused rapid release of the mitochondrially entrapped calcein into the cytosol and nucleus. This major change in permeability of the mitochondrial inner membrane could not be prevented by cyclosporin A. Immunohistochemical study of cytochrome c revealed its diffuse redistribution into the cytoplasm in chloromethyl-X-rosamine-loaded cells after irradiation, as opposed to its specific mitochondrial localisation in non-irradiated cells. As a photosensitiser specifically targeted to mitochondria, and also a reporter of membrane potential and morphology, chloromethyl-X-rosamine may provide versatile new applications in studies of mitochondrial roles in cell death.
13
Zamzami, N., S. A. Susin, P. Marchetti, T. Hirsch, I. Gómez-Monterrey, M. Castedo, and G. Kroemer. "Mitochondrial control of nuclear apoptosis." Journal of Experimental Medicine 183, no. 4 (April 1, 1996): 1533–44. http://dx.doi.org/10.1084/jem.183.4.1533.
Анотація:
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 to be a critical step of the apoptotic cascade.
14
Sharma, Sudha, Papori Sharma, Tara Bailey, Susmita Bhattarai, Utsab Subedi, Chloe Miller, Hosne Ara, et al. "Electrophilic Aldehyde 4-Hydroxy-2-Nonenal Mediated Signaling and Mitochondrial Dysfunction." Biomolecules 12, no. 11 (October 25, 2022): 1555. http://dx.doi.org/10.3390/biom12111555.
Анотація:
Reactive oxygen species (ROS), a by-product of aerobic life, are highly reactive molecules with unpaired electrons. The excess of ROS leads to oxidative stress, instigating the peroxidation of polyunsaturated fatty acids (PUFA) in the lipid membrane through a free radical chain reaction and the formation of the most bioactive aldehyde, known as 4-hydroxynonenal (4-HNE). 4-HNE functions as a signaling molecule and toxic product and acts mainly by forming covalent adducts with nucleophilic functional groups in proteins, nucleic acids, and lipids. The mitochondria have been implicated as a site for 4-HNE generation and adduction. Several studies clarified how 4-HNE affects the mitochondria’s functions, including bioenergetics, calcium homeostasis, and mitochondrial dynamics. Our research group has shown that 4-HNE activates mitochondria apoptosis-inducing factor (AIFM2) translocation and facilitates apoptosis in mice and human heart tissue during anti-cancer treatment. Recently, we demonstrated that a deficiency of SOD2 in the conditional-specific cardiac knockout mouse increases ROS, and subsequent production of 4-HNE inside mitochondria leads to the adduction of several mitochondrial respiratory chain complex proteins. Moreover, we highlighted the physiological functions of HNE and discussed their relevance in human pathophysiology and current discoveries concerning 4-HNE effects on mitochondria.
15
Qian, Wei, Namrata Kumar, Vera Roginskaya, Elise Fouquerel, Patricia L. Opresko, Sruti Shiva, Simon C. Watkins, Dmytro Kolodieznyi, Marcel P. Bruchez, and Bennett Van Houten. "Chemoptogenetic damage to mitochondria causes rapid telomere dysfunction." Proceedings of the National Academy of Sciences 116, no. 37 (August 26, 2019): 18435–44. http://dx.doi.org/10.1073/pnas.1910574116.
Анотація:
Reactive oxygen species (ROS) play important roles in aging, inflammation, and cancer. Mitochondria are an important source of ROS; however, the spatiotemporal ROS events underlying oxidative cellular damage from dysfunctional mitochondria remain unresolved. To this end, we have developed and validated a chemoptogenetic approach that uses a mitochondrially targeted fluorogen-activating peptide (Mito-FAP) to deliver a photosensitizer MG-2I dye exclusively to this organelle. Light-mediated activation (660 nm) of the Mito-FAP–MG-2I complex led to a rapid loss of mitochondrial respiration, decreased electron transport chain complex activity, and mitochondrial fragmentation. Importantly, one round of singlet oxygen produced a persistent secondary wave of mitochondrial superoxide and hydrogen peroxide lasting for over 48 h after the initial insult. By following ROS intermediates, we were able to detect hydrogen peroxide in the nucleus through ratiometric analysis of the oxidation of nuclear cysteine residues. Despite mitochondrial DNA (mtDNA) damage and nuclear oxidative stress induced by dysfunctional mitochondria, there was a lack of gross nuclear DNA strand breaks and apoptosis. Targeted telomere analysis revealed fragile telomeres and telomere loss as well as 53BP1-positive telomere dysfunction-induced foci (TIFs), indicating that DNA double-strand breaks occurred exclusively in telomeres as a direct consequence of mitochondrial dysfunction. These telomere defects activated ataxia-telangiectasia mutated (ATM)-mediated DNA damage repair signaling. Furthermore, ATM inhibition exacerbated the Mito-FAP–induced mitochondrial dysfunction and sensitized cells to apoptotic cell death. This profound sensitivity of telomeres through hydrogen peroxide induced by dysregulated mitochondria reveals a crucial mechanism of telomere–mitochondria communication underlying the pathophysiological role of mitochondrial ROS in human diseases.
16
Costanzini, Anna, Gianluca Sgarbi, Alessandra Maresca, Valentina Del Dotto, Giancarlo Solaini, and Alessandra Baracca. "Mitochondrial Mass Assessment in a Selected Cell Line under Different Metabolic Conditions." Cells 8, no. 11 (November 18, 2019): 1454. http://dx.doi.org/10.3390/cells8111454.
Анотація:
Changes of quantity and/or morphology of cell mitochondria are often associated with metabolic modulation, pathology, and apoptosis. Exogenous fluorescent probes used to investigate changes in mitochondrial content and dynamics are strongly dependent, for their internalization, on the mitochondrial membrane potential and composition, thus limiting the reliability of measurements. To overcome this limitation, genetically encoded recombinant fluorescent proteins, targeted to different cellular districts, were used as reporters. Here, we explored the potential use of mitochondrially targeted red fluorescent probe (mtRFP) to quantify, by flow cytometry, mitochondrial mass changes in cells exposed to different experimental conditions. We first demonstrated that the mtRFP fluorescence intensity is stable during cell culture and it is related with the citrate synthase activity, an established marker of the mitochondrial mass. Incidentally, the expression of mtRFP inside mitochondria did not alter the oxygen consumption rate under both state 3 and 4 respiration conditions. In addition, using this method, we showed for the first time that different inducers of mitochondrial mass change, such as hypoxia exposure or resveratrol treatment of cells, could be consistently detected. We suggest that transfection and selection of stable clones expressing mtRFP is a reliable method to monitor mitochondrial mass changes, particularly when pathophysiological or experimental conditions change ΔΨm, as it occurs during mitochondrial uncoupling or hypoxia/anoxia conditions.
17
Parone, Philippe A., Dominic I. James, Sandrine Da Cruz, Yves Mattenberger, Olivier Donzé, François Barja, and Jean-Claude Martinou. "Inhibiting the Mitochondrial Fission Machinery Does Not Prevent Bax/Bak-Dependent Apoptosis." Molecular and Cellular Biology 26, no. 20 (October 15, 2006): 7397–408. http://dx.doi.org/10.1128/mcb.02282-05.
Анотація:
ABSTRACT Apoptosis, induced by a number of death stimuli, is associated with a fragmentation of the mitochondrial network. These morphological changes in mitochondria have been shown to require proteins, such as Drp1 or hFis1, which are involved in regulating the fission of mitochondria. However, the precise role of mitochondrial fission during apoptosis remains elusive. Here we report that inhibiting the fission machinery in Bax/Bak-mediated apoptosis, by down-regulating of Drp1 or hFis1, prevents the fragmentation of the mitochondrial network and partially inhibits the release of cytochrome c from the mitochondria but fails to block the efflux of Smac/DIABLO. In addition, preventing mitochondrial fragmentation does not inhibit cell death induced by Bax/Bak-dependent death stimuli, in contrast to the effects of Bcl-xL or caspase inhibition. Therefore, the fission of mitochondria is a dispensable event in Bax/Bak-dependent apoptosis.
18
Takatani, Tomoka, Kyoko Takahashi, Yoriko Uozumi, Eriko Shikata, Yasuhiro Yamamoto, Takashi Ito, Takahisa Matsuda, Stephen W. Schaffer, Yasushi Fujio, and Junichi Azuma. "Taurine inhibits apoptosis by preventing formation of the Apaf-1/caspase-9 apoptosome." American Journal of Physiology-Cell Physiology 287, no. 4 (October 2004): C949—C953. http://dx.doi.org/10.1152/ajpcell.00042.2004.
Анотація:
Cardiomyocyte apoptosis contributes to cell death during myocardial infarction. One of the factors that regulate the degree of apoptosis during ischemia is the amino acid taurine. To study the mechanism underlying the beneficial effect of taurine, we examined the interaction between taurine and mitochondria-mediated apoptosis using a simulated ischemia model with cultured rat neonatal cardiomyocytes sealed in closed flasks. Exposure to medium containing 20 mM taurine reduced the degree of apoptosis following periods of ischemia varying from 24 to 72 h. In the untreated group, simulated ischemia for 24 h led to mitochondrial depolarization accompanied by cytochrome c release. The apoptotic cascade was also activated, as evidenced by the activation of caspase-9 and -3. Taurine treatment had no effect on mitochondrial membrane potential and cytochrome c release; however, it inhibited ischemia-induced cleavage of caspase-9 and -3. Taurine loading also suppressed the formation of the Apaf-1/caspase-9 apoptosome and the interaction of caspase-9 with Apaf-1. These findings demonstrate that taurine effectively prevents myocardial ischemia-induced apoptosis by inhibiting the assembly of the Apaf-1/caspase-9 apoptosome.
19
Sionov, Ronit Vogt, Orly Cohen, Shlomit Kfir, Yael Zilberman, and Eitan Yefenof. "Role of mitochondrial glucocorticoid receptor in glucocorticoid-induced apoptosis." Journal of Experimental Medicine 203, no. 1 (January 3, 2006): 189–201. http://dx.doi.org/10.1084/jem.20050433.
Анотація:
The mechanisms by which glucocorticoid receptor (GR) mediates glucocorticoid (GC)-induced apoptosis are unknown. We studied the role of mitochondrial GR in this process. Dexamethasone induces GR translocation to the mitochondria in GC-sensitive, but not in GC-resistant, T cell lines. In contrast, nuclear GR translocation occurs in all cell types. Thymic epithelial cells, which cause apoptosis of the PD1.6 T cell line in a GR-dependent manner, induce GR translocation to the mitochondria, but not to the nucleus, suggesting a role for mitochondrial GR in eliciting apoptosis. This hypothesis is corroborated by the finding that a GR variant exclusively expressed in the mitochondria elicits apoptosis of several cancer cell lines. A putative mitochondrial localization signal was defined to amino acids 558–580 of human GR, which lies within the NH2-terminal part of the ligand-binding domain. Altogether, our data show that mitochondrial and nuclear translocations of GR are differentially regulated, and that mitochondrial GR translocation correlates with susceptibility to GC-induced apoptosis.
20
Parone, Philippe, Muriel Priault, Dominic James, Steven F. Nothwehr, and Jean-Claude Martinou. "Apoptosis: bombarding the mitochondria." Essays in Biochemistry 39 (October 1, 2003): 41–51. http://dx.doi.org/10.1042/bse0390041.
Анотація:
Mitochondria play a central role in apoptosis triggered by many stimuli. They integrate death signals through Bcl-2 family members and co-ordinate caspase activation through the release of apoptogenic factors that are normally sequestered in the mitochondrial intermembrane space. The release of these proteins is the result of the outer mitochondrial membrane becoming permeable. In addition, mitochondria can initiate apoptosis through the production of reactive oxygen species.
21
Synowiec, Ewelina, Grazyna Hoser, Jolanta Bialkowska-Warzecha, Elzbieta Pawlowska, Tomasz Skorski, and Janusz Blasiak. "Doxorubicin Differentially Induces Apoptosis, Expression of Mitochondrial Apoptosis-Related Genes, and Mitochondrial Potential in BCR-ABL1-Expressing Cells Sensitive and Resistant to Imatinib." BioMed Research International 2015 (2015): 1–9. http://dx.doi.org/10.1155/2015/673512.
Анотація:
Imatinib resistance is an emerging problem in the therapy of chronic myeloid leukemia (CML). Because imatinib induces apoptosis, which may be coupled with mitochondria and DNA damage is a prototype apoptosis-inducing factor, we hypothesized that imatinib-sensitive and -resistant CML cells might differentially express apoptosis-related mitochondrially encoded genes in response to genotoxic stress. We investigated the effect of doxorubicin (DOX), a DNA-damaging anticancer drug, on apoptosis and the expression of the mitochondrial NADH dehydrogenase 3 (MT-ND3) and cytochromeb(MT-CYB) in model CML cells showing imatinib resistance caused by Y253H mutation in theBCR-ABL1gene (253) or culturing imatinib-sensitive (S) cells in increasing concentrations of imatinib (AR). The imatinib-resistant 253 cells displayed higher sensitivity to apoptosis induced by 1 μM DOX and this was confirmed by an increased activity of executioner caspases 3 and 7 in those cells. Native mitochondrial potential was lower in imatinib-resistant cells than in their sensitive counterparts and DOX lowered it. MT-CYB mRNA expression in 253 cells was lower than that in S cells and 0.1 μM DOX kept this relationship. In conclusion, imatinib resistance may be associated with altered mitochondrial response to genotoxic stress, which may be further exploited in CML therapy in patients with imatinib resistance.
22
Resanović, Ivana, Emina Sudar-Milovanović, Nikola Bogdanović, Aleksandra Jovanović, Sonja Zafirović, Anastasija Panić, and Esma Isenović. "Fundamentals of apoptosis." Medicinska istrazivanja 49, no. 3 (2015): 42–45. http://dx.doi.org/10.5937/medist1502042r.
Анотація:
Apoptosis is evolutionary conserved, programmed pattern of cell death with an essential role in various physiological processes, such as normal cell turnover and embryonic development, hormone-regulated cell demise, aging, immune system functioning and development and removal of defective and harmful cells. There are two general pathways for activation of apoptosis: the intrinsic and extrinsic pathways. While the intrinsic apoptotic pathway can be triggered by a cytotoxic accumulation of intracellular Ca 2+ , followed permeabilization of mitochondrial membrane and release of pro-apoptotic proteins into the cytosol from mitochondria, the extrinsic mechanisms of apoptosis include the participation of death receptors of tumor necrosis factor-a (TNF-a), receptor superfamily such as TNFR-1, Fas, and TNF-related apoptosis-inducing ligand receptors (TRAIL-R) located on the plasma membrane. There is also the perforin-granzyme pathway that involves T-cell mediated cytotoxicity. All three pathways converge on the same execution pathway, resulting in DNA fragmentation, degradation of cytoskeletal and nuclear proteins, cross-linking of proteins, formation of apoptotic bodies, expression of ligands for phagocytic cell receptors and finally uptake by phagocytic cells. In this review we summarize data from recent studies focusing on apoptotic proteins that have been identified and molecular mechanisms of apoptosis. Understanding apoptotic mechanism might provide useful information and a new approach to prevention and development of new therapies for variety of diseases.
23
Karbowski, Mariusz, Damien Arnoult, Hsiuchen Chen, David C. Chan, Carolyn L. Smith, and Richard J. Youle. "Quantitation of mitochondrial dynamics by photolabeling of individual organelles shows that mitochondrial fusion is blocked during the Bax activation phase of apoptosis." Journal of Cell Biology 164, no. 4 (February 9, 2004): 493–99. http://dx.doi.org/10.1083/jcb.200309082.
Анотація:
A dynamic balance of organelle fusion and fission regulates mitochondrial morphology. During apoptosis this balance is altered, leading to an extensive fragmentation of the mitochondria. Here, we describe a novel assay of mitochondrial dynamics based on confocal imaging of cells expressing a mitochondrial matrix–targeted photoactivable green fluorescent protein that enables detection and quantification of organelle fusion in living cells. Using this assay, we visualize and quantitate mitochondrial fusion rates in healthy and apoptotic cells. During apoptosis, mitochondrial fusion is blocked independently of caspase activation. The block in mitochondrial fusion occurs within the same time range as Bax coalescence on the mitochondria and outer mitochondrial membrane permeabilization, and it may be a consequence of Bax/Bak activation during apoptosis.
24
Pavlov, Evgeny V., Muriel Priault, Dawn Pietkiewicz, Emily H. Y. Cheng, Bruno Antonsson, Stephen Manon, Stanley J. Korsmeyer, Carmen A. Mannella, and Kathleen W. Kinnally. "A novel, high conductance channel of mitochondria linked to apoptosis in mammalian cells and Bax expression in yeast." Journal of Cell Biology 155, no. 5 (November 26, 2001): 725–32. http://dx.doi.org/10.1083/jcb.200107057.
Анотація:
During apoptosis, proapoptotic factors are released from mitochondria by as yet undefined mechanisms. Patch-clamping of mitochondria and proteoliposomes formed from mitochondrial outer membranes of mammalian (FL5.12) cells has uncovered a novel ion channel whose activity correlates with onset of apoptosis. The pore diameter inferred from the largest conductance state of this channel is ∼4 nm, sufficient to allow diffusion of cytochrome c and even larger proteins. The activity of the channel is affected by Bcl-2 family proteins in a manner consistent with their pro- or antiapoptotic properties. Thus, the channel activity correlates with presence of proapoptotic Bax in the mitochondrial outer membrane and is absent in mitochondria from cells overexpressing antiapoptotic Bcl-2. Also, a similar channel activity is found in mitochondrial outer membranes of yeast expressing human Bax. These findings implicate this channel, named mitochondrial apoptosis–induced channel, as a candidate for the outer-membrane pore through which cytochrome c and possibly other factors exit mitochondria during apoptosis.
25
Saleem, Ayesha, Peter J. Adhihetty, and David A. Hood. "Role of p53 in mitochondrial biogenesis and apoptosis in skeletal muscle." Physiological Genomics 37, no. 1 (March 2009): 58–66. http://dx.doi.org/10.1152/physiolgenomics.90346.2008.
Анотація:
p53 is a tumor suppressor protein that also plays a role in regulating aerobic metabolism. Since skeletal muscle is a major source of whole body aerobic respiration, it is important to delineate the effects of p53 on muscle metabolism. In p53 knockout (KO) mice, we observed diminished mitochondrial content in mixed muscle and lowered peroxisome proliferator-activated receptor-γ (PPARγ) coactivator (PGC)-1α protein levels in gastrocnemius muscle. In intermyofibrillar (IMF) mitochondria, lack of p53 was associated with reduced respiration and elevated reactive oxygen species production. Permeability transition pore kinetics remained unchanged; however, IMF mitochondrial cytochrome c release was reduced and DNA fragmentation was lowered, illustrating a resistance to mitochondrially driven apoptosis in muscle of KO mice. p53-null animals displayed similar muscle strength but greater fatigability and less locomotory endurance than wild-type (WT) animals. Surprisingly, the adaptive responses in mitochondrial content to running were similar in WT and KO mice. Thus p53 may be important, but not necessary, for exercise-induced mitochondrial biogenesis. In WT animals, acute muscle contractions induced the phosphorylation of p53 in concert with increased activation of upstream kinases AMP-activated protein kinase and p38, indicating a pathway through which p53 may initiate mitochondrial biogenesis in response to contractile activity. These data illustrate a novel role for p53 in maintaining mitochondrial biogenesis, apoptosis, and performance in skeletal muscle.
26
Zhang, Linlin, Jingyi Qi, Xu Zhang, Xiya Zhao, Peng An, Yongting Luo, and Junjie Luo. "The Regulatory Roles of Mitochondrial Calcium and the Mitochondrial Calcium Uniporter in Tumor Cells." International Journal of Molecular Sciences 23, no. 12 (June 15, 2022): 6667. http://dx.doi.org/10.3390/ijms23126667.
Анотація:
Mitochondria, as the main site of cellular energy metabolism and the generation of oxygen free radicals, are the key switch for mitochondria-mediated endogenous apoptosis. Ca2+ is not only an important messenger for cell proliferation, but it is also an indispensable signal for cell death. Ca2+ participates in and plays a crucial role in the energy metabolism, physiology, and pathology of mitochondria. Mitochondria control the uptake and release of Ca2+ through channels/transporters, such as the mitochondrial calcium uniporter (MCU), and influence the concentration of Ca2+ in both mitochondria and cytoplasm, thereby regulating cellular Ca2+ homeostasis. Mitochondrial Ca2+ transport-related processes are involved in important biological processes of tumor cells including proliferation, metabolism, and apoptosis. In particular, MCU and its regulatory proteins represent a new era in the study of MCU-mediated mitochondrial Ca2+ homeostasis in tumors. Through an in-depth analysis of the close correlation between mitochondrial Ca2+ and energy metabolism, autophagy, and apoptosis of tumor cells, we can provide a valuable reference for further understanding of how mitochondrial Ca2+ regulation helps diagnosis and therapy.
27
Su, Ching-Chieh, Jia-Ying Yang, Hsin-Ban Leu, Yumay Chen, and Ping H. Wang. "Mitochondrial Akt-regulated mitochondrial apoptosis signaling in cardiac muscle cells." American Journal of Physiology-Heart and Circulatory Physiology 302, no. 3 (February 2012): H716—H723. http://dx.doi.org/10.1152/ajpheart.00455.2011.
Анотація:
We recently reported translocation and activation of Akt in cardiac mitochondria. This study was to determine whether activation of Akt in mitochondria could inhibit apoptosis of cardiac muscle cells. Insulin stimulation induced translocation of phosphorylated Akt to the mitochondria in primary cardiomyocytes. A mitochondria-targeted constitutively active Akt was overexpressed via adenoviral vector and inhibited efflux of cytochrome c and apoptosis-inducing factor from mitochondria to cytosol and partially prevented loss of mitochondria cross-membrane electrochemical gradient. Activation of caspase 3 was suppressed in the cardiomyocytes transduced with mitochondria-targeted active Akt, whereas a mitochondria-targeted dominant negative Akt enhanced activation of caspase 3. Terminal deoxynucleotidyl transferase dUTP-mediated nick-end labeling assay showed that mitochondrial activation of Akt significantly reduced the number of apoptotic cells. When the endogenous Akt was abolished by LY294002, the antiapoptotic actions of mitochondrial Akt remained effective. These experiments suggested that mitochondrial Akt suppressed apoptosis signaling independent of cytosolic Akt in cardiac muscle cells.
28
Wang, Hongji, Chaowen Zhang, Mengnan Li, Chaoran Liu, Jingyi Wang, Xuan Ou, and Yuzhu Han. "Antimicrobial Peptides Mediate Apoptosis by Changing Mitochondrial Membrane Permeability." International Journal of Molecular Sciences 23, no. 21 (October 22, 2022): 12732. http://dx.doi.org/10.3390/ijms232112732.
Анотація:
Changes in mitochondrial membrane permeability are closely associated with mitochondria-mediated apoptosis. Antimicrobial peptides (AMPs), which have been found to enter cells to exert physiological effects, cause damage to the mitochondria. This paper reviews the molecular mechanisms of AMP-mediated apoptosis by changing the permeability of the mitochondrial membrane through three pathways: the outer mitochondrial membrane (OMM), inner mitochondrial membrane (IMM), and mitochondrial permeability transition pore (MPTP). The roles of AMPs in inducing changes in membrane permeability and apoptosis are also discussed. Combined with recent research results, the possible application prospects of AMPs are proposed to provide a theoretical reference for the development of AMPs as therapeutic agents for human diseases.
29
Dhar, Sanjit Kumar, and Daret K. St. Clair. "Nucleophosmin Blocks Mitochondrial Localization of p53 and Apoptosis." Journal of Biological Chemistry 284, no. 24 (April 14, 2009): 16409–18. http://dx.doi.org/10.1074/jbc.m109.005736.
Анотація:
Activation of p53 is an important mechanism in apoptosis. However, whether the presence of p53 in mitochondria plays an important role in p53-mediated apoptosis is unclear. Here, we demonstrate that overexpression of NPM (nucleophosmin) significantly suppresses 12-O-tetradecanoylphorbol 13-acetate (TPA)-mediated apoptosis, in part, by blocking the mitochondrial localization of p53. Within 1 h following TPA treatment of skin epithelial (JB6) cells, p53 accumulated in mitochondria. Expression of NPM enhances p53 levels in the nucleus but reduces p53 levels in mitochondria, as detected by immunocytochemistry and Western blot analysis. The suppressive effect of NPM on p53 mitochondrial localization is also observed in TPA-treated primary epithelial cells and in JB6 cells treated with doxorubicin. NPM enhances the expression of p53 target gene p21 and bax. However, the increase in Bax level in the absence of p53 in mitochondria did not lead to an increase in TPA-induced apoptosis, suggesting that the presence of p53 in mitochondria is important. Suppression of NPM by NPM small interfering RNA leads to an increase of p53 levels in mitochondria and apoptosis. Furthermore, suppression of NPM in tumor cells with a high constitutive level of NPM results in p53 translocation to mitochondria and enhances TPA-mediated apoptosis. The results demonstrate the effect of NPM on p53 localization in mitochondria and apoptosis. Together, the data indicate that the presence of p53 in mitochondria plays an important role in stress-induced apoptosis and suggest that NPM may protect cells from apoptosis by reducing the mitochondrial level of p53.
30
Gao, Wenhua, Yongmei Pu, Kathy Q. Luo, and Donald C. Chang. "Temporal relationship between cytochrome c release and mitochondrial swelling during UV-induced apoptosis in living HeLa cells." Journal of Cell Science 114, no. 15 (August 1, 2001): 2855–62. http://dx.doi.org/10.1242/jcs.114.15.2855.
Анотація:
During apoptosis, cytochrome c is released from mitochondria to the cytosol to activate a caspase cascade, which commits the cell to the death process. It has been proposed that the release of cytochrome c is caused by a swelling of the mitochondrial matrix triggered by the apoptotic stimuli. To test this theory, we measured directly the dynamic re-distribution of green fluorescence protein (GFP)-tagged cytochrome c and morphological change of mitochondria within living HeLa cells during u.v.-induced apoptosis. We observed that mitochondria did not swell when cytochrome c was released from mitochondria to cytosol during apoptosis. Instead, mitochondria swelled to spherical shapes within 10 minutes of cytochrome c release. This finding strongly suggests that cytochrome c release in apoptosis was not caused by mitochondrial swelling. This conclusion was further supported in two separated experiments using an immunostaining method and carbonyl cyanide m-chlorophenyl-hydrazone (CCCP) treatment. In addition, we found evidence that cytochrome c was also released before mitochondrial swelling in apoptosis induced by other cell death-inducing treatments, including tumor necrosis factor (TNF) and actinomycin D.
31
Kaczmarek, Agata, Anna Katarzyna Wrońska, and Mieczysława Irena Boguś. "The Changes in Mitochondrial Morphology and Physiology Accompanying Apoptosis in Galleria mellonella (Lepidoptera) Immunocompetent Cells during Conidiobolus coronatus (Entomophthorales) Infection." International Journal of Molecular Sciences 24, no. 12 (June 15, 2023): 10169. http://dx.doi.org/10.3390/ijms241210169.
Анотація:
Mitochondria have been shown to play an important role in apoptosis using mammalian cell lines. However, their role in insects is not fully understood; thus, more indepth studies of insect cell apoptosis are necessary. The present study investigates mitochondrial involvement during Conidiobolus coronatus-induced apoptosis in Galleria mellonella hemocytes. Previous research has shown that fungal infection could induce apoptosis in insect hemocytes. Our findings indicate that mitochondria undergo several morphological and physiological changes during fungal infection, e.g., loss of mitochondrial membrane potential, megachannel formation, disturbances in intracellular respiration, increased nonrespiratory oxygen consumption in mitochondria, decreased ATP-coupled oxygen consumption and increased non-ATP–coupled oxygen consumption, decreased extracellular and intracellular oxygen consumption, and increased extracellular pH. Our findings confirm that G. mellonella immunocompetent cells demonstrate Ca2+ overload in mitochondria, translocation of cytochrome c-like protein from mitochondrial to cytosol fraction, and higher activation of caspase-9-like protein after C. coronatus infection. Most importantly, several of the changes observed in insect mitochondria are similar to those accompanying apoptosis in mammalian cells, suggesting that the process is evolutionarily conserved.
32
Wang, Xiuli, Yi Wang, Lulu Zhang, Da Zhang, Lu Bai, Wei Kong, Yaqian Huang, Chaoshu Tang, Junbao Du, and Hongfang Jin. "L-Cystathionine Protects against Homocysteine-Induced Mitochondria-Dependent Apoptosis of Vascular Endothelial Cells." Oxidative Medicine and Cellular Longevity 2019 (November 25, 2019): 1–13. http://dx.doi.org/10.1155/2019/1253289.
Анотація:
The study was aimed at investigating the effects of L-cystathionine on vascular endothelial cell apoptosis and its mechanisms. Cultured human umbilical vein endothelial cells (HUVECs) were used in the study. Apoptosis of vascular endothelial cells was induced by homocysteine. Apoptosis, mitochondrial superoxide anion, mitochondrial membrane potential, mitochondrial permeability transition pore (MPTP) opening, and caspase-9 and caspase-3 activities were examined. Expression of Bax, Bcl-2, and cleaved caspase-3 was tested and BTSA1, a Bax agonist, and HUVEC Bax overexpression was used in the study. Results showed that homocysteine obviously induced the apoptosis of HUVECs, and this effect was significantly attenuated by the pretreatment with L-cystathionine. Furthermore, L-cystathionine decreased the production of mitochondrial superoxide anion and the expression of Bax and restrained its translocation to mitochondria, increased mitochondrial membrane potential, inhibited mitochondrial permeability transition pore (MPTP) opening, suppressed the leakage of cytochrome c from mitochondria into the cytoplasm, and downregulated activities of caspase-9 and caspase-3. However, BTSA1, a Bax agonist, or Bax overexpression successfully abolished the inhibitory effect of L-cystathionine on Hcy-induced MPTP opening, caspase-9 and caspase-3 activation, and HUVEC apoptosis. Taken together, our results indicated that L-cystathionine could protect against homocysteine-induced mitochondria-dependent apoptosis of HUVECs.
33
MacDonald, Glen, Lianfa Shi, Christine Vande Velde, Judy Lieberman, and Arnold H. Greenberg. "Mitochondria-dependent and -independent Regulation of Granzyme B–induced Apoptosis." Journal of Experimental Medicine 189, no. 1 (January 4, 1999): 131–44. http://dx.doi.org/10.1084/jem.189.1.131.
Анотація:
Granzyme B (GraB) is required for the efficient activation of apoptosis by cytotoxic T lymphocytes and natural killer cells. We find that GraB and perforin induce severe mitochondrial perturbation as evidenced by the release of cytochrome c into the cytosol and suppression of transmembrane potential (Δψ). The earliest mitochondrial event was the release of cytochrome c, which occurred at the same time as caspase 3 processing and consistently before the activation of apoptosis. Granzyme K/perforin or perforin treatment, both of which kill target cells efficiently but are poor activators of apoptosis in short-term assays, did not induce rapid cytochrome c release. However, they suppressed Δψ and increased reactive oxygen species generation, indicating that mitochondrial dysfunction is also associated with this nonapoptotic cell death. Pretreatment with peptide caspase inhibitors zVAD-FMK or YVAD-CHO prevented GraB apoptosis and cytochrome c release, whereas DEVD-CHO blocked apoptosis but did not prevent cytochrome c release, indicating that caspases act both up- and downstream of mitochondria. Of additional interest, Δψ suppression mediated by GraK or GraB and perforin was not affected by zVAD-FMK and thus was caspase independent. Overexpression of Bcl-2 and Bcl-XL suppressed caspase activation, mitochondrial cytochrome c release, Δψ suppression, and apoptosis and cell death induced by GraB, GraK, or perforin. In an in vitro cell free system, GraB activates nuclear apoptosis in S-100 cytosol at high doses, however the addition of mitochondria amplified GraB activity over 15-fold. GraB- induced caspase 3 processing to p17 in S-100 cytosol was increased only threefold in the presence of mitochondria, suggesting that another caspase(s) participates in the mitochondrial amplification of GraB apoptosis. We conclude that GraB-induced apoptosis is highly amplified by mitochondria in a caspase-dependent manner but that GraB can also initiate caspase 3 processing and apoptosis in the absence of mitochondria.
34
Xie, Qiang, Jun Zeng, Yongtao Zheng, Tianwen Li, Junwei Ren, Kezhu Chen, Quan Zhang, Rong Xie, Feng Xu, and Jianhong Zhu. "Mitochondrial Transplantation Attenuates Cerebral Ischemia-Reperfusion Injury: Possible Involvement of Mitochondrial Component Separation." Oxidative Medicine and Cellular Longevity 2021 (November 20, 2021): 1–21. http://dx.doi.org/10.1155/2021/1006636.
Анотація:
Background. Mitochondrial dysfunctions play a pivotal role in cerebral ischemia-reperfusion (I/R) injury. Although mitochondrial transplantation has been recently explored for the treatment of cerebral I/R injury, the underlying mechanisms and fate of transplanted mitochondria are still poorly understood. Methods. Mitochondrial morphology and function were assessed by fluorescent staining, electron microscopy, JC-1, PCR, mitochondrial stress testing, and metabolomics. Therapeutic effects of mitochondria were evaluated by cell viability, reactive oxygen species (ROS), and apoptosis levels in a cellular hypoxia-reoxygenation model. Rat middle cerebral artery occlusion model was applied to assess the mitochondrial therapy in vivo. Transcriptomics was performed to explore the underlying mechanisms. Mitochondrial fate tracking was implemented by a variety of fluorescent labeling methods. Results. Neuro-2a (N2a) cell-derived mitochondria had higher mitochondrial membrane potential, more active oxidative respiration capacity, and less mitochondrial DNA copy number. Exogenous mitochondrial transplantation increased cellular viability in an oxygen-dependent manner, decreased ROS and apoptosis levels, improved neurobehavioral deficits, and reduced infarct size. Transcriptomic data showed that the differential gene enrichment pathways are associated with metabolism, especially lipid metabolism. Mitochondrial tracking indicated specific parts of the exogenous mitochondria fused with the mitochondria of the host cell, and others were incorporated into lysosomes. This process occurred at the beginning of internalization and its efficiency is related to intercellular connection. Conclusions. Mitochondrial transplantation may attenuate cerebral I/R injury. The mechanism may be related to mitochondrial component separation, altering cellular metabolism, reducing ROS, and apoptosis in an oxygen-dependent manner. The way of isolated mitochondrial transfer into the cell may be related to intercellular connection.
35
Álvarez-Illera, Pilar, Paloma García-Casas, Rosalba I. Fonteriz, Mayte Montero, and Javier Alvarez. "Mitochondrial Ca2+ Dynamics in MCU Knockout C. elegans Worms." International Journal of Molecular Sciences 21, no. 22 (November 16, 2020): 8622. http://dx.doi.org/10.3390/ijms21228622.
Анотація:
Mitochondrial [Ca2+] plays an important role in the regulation of mitochondrial function, controlling ATP production and apoptosis triggered by mitochondrial Ca2+ overload. This regulation depends on Ca2+ entry into the mitochondria during cell activation processes, which is thought to occur through the mitochondrial Ca2+ uniporter (MCU). Here, we have studied the mitochondrial Ca2+ dynamics in control and MCU-defective C. elegans worms in vivo, by using worms expressing mitochondrially-targeted YC3.60 yellow cameleon in pharynx muscle. Our data show that the small mitochondrial Ca2+ oscillations that occur during normal physiological activity of the pharynx were very similar in both control and MCU-defective worms, except for some kinetic differences that could mostly be explained by changes in neuronal stimulation of the pharynx. However, direct pharynx muscle stimulation with carbachol triggered a large and prolonged increase in mitochondrial [Ca2+] that was much larger in control worms than in MCU-defective worms. This suggests that MCU is necessary for the fast mitochondrial Ca2+ uptake induced by large cell stimulations. However, low-amplitude mitochondrial Ca2+ oscillations occurring under more physiological conditions are independent of the MCU and use a different Ca2+ pathway.
36
Otera, Hidenori, and Katsuyoshi Mihara. "Mitochondrial Dynamics: Functional Link with Apoptosis." International Journal of Cell Biology 2012 (2012): 1–10. http://dx.doi.org/10.1155/2012/821676.
Анотація:
Mitochondria participate in a variety of physiologic processes, such as ATP production, lipid metabolism, iron-sulfur cluster biogenesis, and calcium buffering. The morphology of mitochondria changes dynamically due to their frequent fusion and division in response to cellular conditions, and these dynamics are an important constituent of apoptosis. The discovery of large GTPase family proteins that regulate mitochondrial dynamics, together with novel insights into the role of mitochondrial fusion and fission in apoptosis, has provided important clues to understanding the molecular mechanisms of cellular apoptosis. In this paper, we briefly summarize current knowledge of the role of mitochondrial dynamics in apoptosis and cell pathophysiology in mammalian cells.
37
van der Toorn, Marco, Dirk-Jan Slebos, Harold G. de Bruin, Henri G. Leuvenink, Stephan J. L. Bakker, Rijk O. B. Gans, Gerard H. Koëter, Antoon J. M. van Oosterhout, and Henk F. Kauffman. "Cigarette smoke-induced blockade of the mitochondrial respiratory chain switches lung epithelial cell apoptosis into necrosis." American Journal of Physiology-Lung Cellular and Molecular Physiology 292, no. 5 (May 2007): L1211—L1218. http://dx.doi.org/10.1152/ajplung.00291.2006.
Анотація:
Increased lung cell apoptosis and necrosis occur in patients with chronic obstructive pulmonary disease (COPD). Mitochondria are crucially involved in the regulation of these cell death processes. Cigarette smoke is the main risk factor for development of COPD. We hypothesized that cigarette smoke disturbs mitochondrial function, thereby decreasing the capacity of mitochondria for ATP synthesis, leading to cellular necrosis. This hypothesis was tested in both human bronchial epithelial cells and isolated mitochondria. Cigarette smoke extract exposure resulted in a dose-dependent inhibition of complex I and II activities. This inhibition was accompanied by decreases in mitochondrial membrane potential, mitochondrial oxygen consumption, and production of ATP. Cigarette smoke extract abolished the staurosporin-induced caspase-3 and -7 activities and induced a switch from epithelial cell apoptosis into necrosis. Cigarette smoke induced mitochondrial dysfunction, with compounds of cigarette smoke acting as blocking agents of the mitochondrial respiratory chain; loss of ATP generation leading to cellular necrosis instead of apoptosis is a new pathophysiological concept of COPD development.
38
Li, Yan, Hong-Ying Li, Jun Shao, Lingpeng Zhu, Tian-Hua Xie, Jiping Cai, Wenjuan Wang, et al. "GRP75 Modulates Endoplasmic Reticulum–Mitochondria Coupling and Accelerates Ca2+-Dependent Endothelial Cell Apoptosis in Diabetic Retinopathy." Biomolecules 12, no. 12 (November 29, 2022): 1778. http://dx.doi.org/10.3390/biom12121778.
Анотація:
Endoplasmic reticulum (ER) and mitochondrial dysfunction play fundamental roles in the pathogenesis of diabetic retinopathy (DR). However, the interrelationship between the ER and mitochondria are poorly understood in DR. Here, we established high glucose (HG) or advanced glycosylation end products (AGE)-induced human retinal vascular endothelial cell (RMEC) models in vitro, as well as a streptozotocin (STZ)-induced DR rat model in vivo. Our data demonstrated that there was increased ER–mitochondria coupling in the RMECs, which was accompanied by elevated mitochondrial calcium ions (Ca2+) and mitochondrial dysfunction under HG or AGE incubation. Mechanistically, ER–mitochondria coupling was increased through activation of the IP3R1–GRP75–VDAC1 axis, which transferred Ca2+ from the ER to the mitochondria. Elevated mitochondrial Ca2+ led to an increase in mitochondrial ROS and a decline in mitochondrial membrane potential. These events resulted in the elevation of mitochondrial permeability and induced the release of cytochrome c from the mitochondria into the cytoplasm, which further activated caspase-3 and promoted apoptosis. The above phenomenon was also observed in tunicamycin (TUN, ER stress inducer)-treated cells. Meanwhile, BAPTA-AM (calcium chelator) rescued mitochondrial dysfunction and apoptosis in DR, which further confirmed of our suspicions. In addition, 4-phenylbutyric acid (4-PBA), an ER stress inhibitor, was shown to reverse retinal dysfunction in STZ-induced DR rats in vivo. Taken together, our findings demonstrated that DR fueled the formation of ER–mitochondria coupling via the IP3R1–GRP75–VDAC1 axis and accelerated Ca2+-dependent cell apoptosis. Our results demonstrated that inhibition of ER–mitochondrial coupling, including inhibition of GRP75 or Ca2+ overload, may be a potential therapeutic target in DR.
39
Poulaki, Aikaterini, and Stavroula Giannouli. "Mitochondrial Lipids: From Membrane Organization to Apoptotic Facilitation." International Journal of Molecular Sciences 23, no. 7 (March 29, 2022): 3738. http://dx.doi.org/10.3390/ijms23073738.
Анотація:
Mitochondria are the most complex intracellular organelles, their function combining energy production for survival and apoptosis facilitation for death. Such a multivariate physiology is structurally and functionally reflected upon their membrane configuration and lipid composition. Mitochondrial double membrane lipids, with cardiolipin as the protagonist, show an impressive level of complexity that is mandatory for maintenance of mitochondrial health and protection from apoptosis. Given that lipidomics is an emerging field in cancer research and that mitochondria are the organelles with the most important role in malignant maintenance knowledge of the mitochondrial membrane, lipid physiology in health is mandatory. In this review, we will thus describe the delicate nature of the healthy mitochondrial double membrane and its role in apoptosis. Emphasis will be given on mitochondrial membrane lipids and the changes that they undergo during apoptosis induction and progression.
40
Seo, Young Ah, Veronica Lopez, and Shannon L. Kelleher. "A histidine-rich motif mediates mitochondrial localization of ZnT2 to modulate mitochondrial function." American Journal of Physiology-Cell Physiology 300, no. 6 (June 2011): C1479—C1489. http://dx.doi.org/10.1152/ajpcell.00420.2010.
Анотація:
Female reproductive tissues such as mammary glands, ovaries, uterus, and placenta are phenotypically dynamic, requiring tight integration of bioenergetic and apoptotic mechanisms. Mitochondrial zinc (Zn) pools have emerged as a central player in regulating bioenergetics and apoptosis. Zn must first be imported into mitochondria to modulate mitochondrion-specific functions; however, mitochondrial Zn import mechanisms have not been identified. Here we documented that the Zn transporter ZnT2 is associated with the inner mitochondrial membrane and acts as an auxiliary Zn importer into mitochondria in mammary cells. We found that attenuation of ZnT2 expression significantly reduced mitochondrial Zn uptake and total mitochondrial Zn pools. Moreover, expression of a ZnT2-hemagglutinin (HA) fusion protein was localized to mitochondria and significantly increased Zn uptake and mitochondrial Zn pools, directly implicating ZnT2 in Zn import into mitochondria. Confocal microscopy of truncated and point mutants of ZnT2-green fluorescent protein (GFP) fusion proteins revealed a histidine-rich motif (51HH XH54) in the NH2 terminus that is important for mitochondrial targeting of ZnT2. More importantly, the expansion of mitochondrial Zn pools by ZnT2 overexpression significantly reduced ATP biogenesis and mitochondrial oxidation concurrent with increased apoptosis, suggesting a functional role for ZnT2-mediated Zn import into mitochondria. These results identify the first Zn transporter directly associated with mitochondria and suggest that unique secretory tissues such as the mammary gland require novel mechanisms to modulate mitochondrion-specific functions.
41
Read, Stuart H., Belinda C. Baliga, Paul G. Ekert, David L. Vaux, and Sharad Kumar. "A novel Apaf-1–independent putative caspase-2 activation complex." Journal of Cell Biology 159, no. 5 (December 2, 2002): 739–45. http://dx.doi.org/10.1083/jcb.200209004.
Анотація:
CVaspase activation is a key event in apoptosis execution. In stress-induced apoptosis, the mitochondrial pathway of caspase activation is believed to be of central importance. In this pathway, cytochrome c released from mitochondria facilitates the formation of an Apaf-1 apoptosome that recruits and activates caspase-9. Recent data indicate that in some cells caspase-9 may not be the initiator caspase in stress-mediated apoptosis because caspase-2 is required upstream of mitochondria for the release of cytochrome c and other apoptogenic factors. To determine how caspase-2 is activated, we have studied the formation of a complex that mediates caspase-2 activation. Using gel filtration analysis of cell lysates, we show that caspase-2 is spontaneously recruited to a large protein complex independent of cytochrome c and Apaf-1 and that recruitment of caspase-2 to this complex is sufficient to mediate its activation. Using substrate-binding assays, we also provide the first evidence that caspase-2 activation may occur without processing of the precursor molecule. Our data are consistent with a model where caspase-2 activation occurs by oligomerization, independent of the Apaf-1 apoptosome.
42
Kroemer, Guido. "Mitochondrial control of apoptosis: an overview." Biochemical Society Symposia 66 (September 1, 1999): 1–15. http://dx.doi.org/10.1042/bss0660001.
Анотація:
The mitochondrial permeability transition (PT) pore, also called the mitochondrial megachannel, is a multiprotein complex formed at the contact site between the mitochondrial inner and outer membranes, exactly the same location at which Bax, Bcl-2 and Bcl-XL are particularly abundant. The PT pore participates in the regulation of matrix Ca2+, pH, transmembrane potential and volume, and functions as a Ca2+-, voltage-, pH- and redox-gated channel with several levels of conductance and little, if any, ion selectivity. We have obtained three independent lines of evidence implicating the mitochondrial PT pore in apoptosis. First, in intact cells, apoptosis is accompanied by an early dissipation of the mitochondrial transmembrane potential, ΔΨm. In several models of apoptosis, specific agents inhibiting the mitochondrial PT pore abolish this dissipation of the ΔΨm and simultaneously prevent activation of downstream caspases and endonucleases, indicating that PT pore opening can be a critical event of the apoptotic process. Secondly, mitochondria are rate-limiting for caspase and nuclease activation in several cell-free systems of apoptosis. Isolated mitochondria release apoptogenic factors capable of activating pro-caspases or endonucleases upon opening of the mitochondrial megachannel in vitro. Thirdly, opening of the purified PT pore complex reconstituted into liposomes is inhibited by recombinant Bcl-2 or Bcl-XL, two apoptosis-inhibitory proteins that also prevent PT pore opening in cells and isolated mitochondria. Altogether, our results suggest that PT pore opening is sufficient and (mostly) necessary for triggering apoptosis. The implications of these findings are examined in the light of pharmacological interventions in apoptosis.
43
Tang, Ho Lam, Anh-Huy Phan Le, and Hong Lok Lung. "The increase in mitochondrial association with actin precedes Bax translocation in apoptosis." Biochemical Journal 396, no. 1 (April 26, 2006): 1–5. http://dx.doi.org/10.1042/bj20060241.
Анотація:
Accumulating evidence indicates the potential role of actin cytoskeleton in facilitating the mitochondrial recruitment of various pro-apoptotic proteins from the cytosol to initiate apoptosis. In the present paper, we report the observation of the increase in mitochondrial association of actin in early apoptosis. Using cell fractionation and Western blot analysis, we found that mitochondrial accumulation of β-actin occurred before the mitochondrial insertion of Bax and release of cytochrome c in apoptosis. The mitochondrial accumulation of β-actin was observed with various apoptotic stimuli in various cell lines, suggesting that this is a general apoptotic phenomenon in mammalian systems. Using fluorescence microscopy, we have shown that an apoptotic induction triggered the reorganization of the F-actin (filamentous actin) network with an increase in the association with mitochondria, which was observed before mitochondrial fission and nuclear condensation. Perhaps actin could contribute to the initiation of apoptosis by enabling cytosolic pro-apoptotic proteins to be carried to mitochondria by the cytoskeleton-driven trafficking system.
44
Khera, Samira Y., and Nan-Shan Chang. "Role of p53 Tumor Suppressor in Mitochondrial Apoptosis." Guthrie Journal 70, no. 3 (July 2001): 98–103. http://dx.doi.org/10.3138/guthrie.70.3.098.
Анотація:
The p53 tumor suppressor plays an important role in controlling gene expression, cell growth and apoptosis. Mutation of p53 has been found in more than 50% of cancers, suggesting its role in cancer development. P53 induces the expression of a variety of apoptosis inducing proteins, some of which are located in mitochondria. In addition to its nuclear localization, p53 is also found in the mitochondria and translocates from the nucleus to this organelle during apoptosis. P53 appears to play a homeostatic role of mitochondrial biogenesis, function and apoptosis. P53 physically associates with a mitochondrial protein WOX1 (WW domain oxidoreductase). Without WOX1, the p53 apoptotic function is impaired. This review discusses the functional significance of p53 and WOX1 in mitochondrial apoptosis.
45
Feng, Yongmei, Maria E. Ariza, Anne-Christine Goulet, Jiaqi Shi, and Mark A. Nelson. "Death-signal-induced relocalization of cyclin-dependent kinase 11 to mitochondria." Biochemical Journal 392, no. 1 (November 8, 2005): 65–73. http://dx.doi.org/10.1042/bj20050195.
Анотація:
Fas receptor–Fas ligand interaction appears to be important in carcinogenesis, tumour outgrowth and metastasis. Emerging evidence suggests that CDK11 (cyclin-dependent kinase 11) plays a role in apoptosis and melanoma development. Here, we show that CDK11p110 protein kinase was cleaved after induction of apoptosis by Fas. The N-terminal portion of CDK11p110, CDK11p60, was translocated from the nucleus to the mitochondria. The targeting of CDK11p60 to mitochondria occurred as early as 12 h after treatment. Overexpression of EGFP (enhanced green fluorescent protein)-tagged CDK11p60 could partially break down the mitochondrial membrane potential, induce cytochrome c release and promote apoptosis. Reduction of endogenous CDK11p110 protein levels with siRNA (small interfering RNA) resulted in the suppression of both cytochrome c release and apoptosis. In addition, subcellular fractionation studies of Fas-mediated apoptosis demonstrated that CDK11p60 was associated with the mitochondrial import motor, mitochondrial heat shock protein 70. Taken together, our data suggest that CDK11p60 can contribute to apoptosis by direct signalling at the mitochondria, thereby amplifying Fas-induced apoptosis in melanoma cells.
46
Waterhouse, Nigel J., Joshua C. Goldstein, Oliver von Ahsen, Martin Schuler, Donald D. Newmeyer, and Douglas R. Green. "Cytochrome C Maintains Mitochondrial Transmembrane Potential and Atp Generation after Outer Mitochondrial Membrane Permeabilization during the Apoptotic Process." Journal of Cell Biology 153, no. 2 (April 16, 2001): 319–28. http://dx.doi.org/10.1083/jcb.153.2.319.
Анотація:
During apoptosis, cytochrome c is released into the cytosol as the outer membrane of mitochondria becomes permeable, and this acts to trigger caspase activation. The consequences of this release for mitochondrial metabolism are unclear. Using single-cell analysis, we found that when caspase activity is inhibited, mitochondrial outer membrane permeabilization causes a rapid depolarization of mitochondrial transmembrane potential, which recovers to original levels over the next 30–60 min and is then maintained. After outer membrane permeabilization, mitochondria can use cytoplasmic cytochrome c to maintain mitochondrial transmembrane potential and ATP production. Furthermore, both cytochrome c release and apoptosis proceed normally in cells in which mitochondria have been uncoupled. These studies demonstrate that cytochrome c release does not affect the integrity of the mitochondrial inner membrane and that, in the absence of caspase activation, mitochondrial functions can be maintained after the release of cytochrome c.
47
Su, Jin, Gen Wang, John W. Barrett, Timothy S. Irvine, Xiujuan Gao, and Grant McFadden. "Myxoma Virus M11L Blocks Apoptosis through Inhibition of Conformational Activation of Bax at the Mitochondria." Journal of Virology 80, no. 3 (February 1, 2006): 1140–51. http://dx.doi.org/10.1128/jvi.80.3.1140-1151.2006.
Анотація:
ABSTRACT Many viruses inhibit or retard apoptosis, a strategy that subverts one of the most ancient antiviral mechanisms. M11L, a myxoma virus-encoded antiapoptotic protein, has been previously shown to localize to mitochondria and block apoptosis of virus-infected cells (H. Everett, M. Barry, S. F. Lee, X. J. Sun, K. Graham, J. Stone, R. C. Bleackley, and G. McFadden, J. Exp. Med. 191:1487-1498, 2000; H. Everett, M. Barry, X. Sun, S. F. Lee, C. Frantz, L. G. Berthiaume, G. McFadden, and R. C. Bleackley, J. Exp. Med. 196:1127-1139, 2002; and G. Wang, J. W. Barrett, S. H. Nazarian, H. Everett, X. Gao, C. Bleackley, K. Colwill, M. F. Moran, and G. McFadden, J. Virol. 78:7097-7111, 2004). This protection from apoptosis involves constitutive-forming inhibitory complexes with the peripheral benzodiazepine receptor and Bak on the outer mitochondrial membrane. Here, we extend the study to investigate the interference of M11L with Bax activation during the process of apoptosis. Myxoma virus infection triggers an early apoptotic signal that induces rapid Bax translocation from cytoplasm to mitochondria, despite the existence of various viral antiapoptotic proteins. However, in the presence of M11L, the structural activation of Bax at the mitochondrial membrane, which is characterized by the occurrence of a Bax conformational change, is blocked in both M11L-expressing myxoma-infected cells and M11L-transfected cells under apoptotic stimulation. In addition, inducible binding of M11L to the mitochondrially localized Bax is detected in myxoma virus-infected cells and in M11L/Bax-cotransfected cells as measured by immunoprecipitation and tandem affinity purification analysis, respectively. Importantly, this inducible Bax/M11L interaction is independent of Bak, demonstrated by the complete block of Bax-mediated apoptosis in myxoma-infected cells that lack Bak expression. Our findings reveal that myxoma M11L modulates apoptosis by multiple independent strategies which all contribute to the blockade of apoptosis at the mitochondrial checkpoint.
48
Sugioka, Rie, Shigeomi Shimizu, and Yoshihide Tsujimoto. "Fzo1, a Protein Involved in Mitochondrial Fusion, Inhibits Apoptosis." Journal of Biological Chemistry 279, no. 50 (September 30, 2004): 52726–34. http://dx.doi.org/10.1074/jbc.m408910200.
Анотація:
Mitochondrial morphology and physiology are regulated by the processes of fusion and fission. Some forms of apoptosis are reported to be associated with mitochondrial fragmentation. We showed that overexpression of Fzo1A/B (rat) proteins involved in mitochondrial fusion, or silencing of Dnm1 (rat)/Drp1 (human) (a mitochondrial fission protein), increased elongated mitochondria in healthy cells. After apoptotic stimulation, these interventions inhibited mitochondrial fragmentation and cell death, suggesting that a process involved in mitochondrial fusion/fission might play a role in the regulation of apoptosis. Consistently, silencing of Fzo1A/B or Mfn1/2 (a human homolog of Fzo1A/B) led to an increase of shorter mitochondria and enhanced apoptotic death. Overexpression of Fzo1 inhibited cytochromecrelease and activation of Bax/Bak, as assessed from conformational changes and oligomerization. Silencing of Mfn or Drp1 caused an increase or decrease of mitochondrial sensitivity to apoptotic stimulation, respectively. These results indicate that some of the proteins involved in mitochondrial fusion/fission modulate apoptotic cell death at the mitochondrial level.
49
Adachi, Masayuki, Hajime Higuchi, Soichiro Miura, Toshifumi Azuma, Sayaka Inokuchi, Hidetsugu Saito, Shinzo Kato, and Hiromasa Ishii. "Bax interacts with the voltage-dependent anion channel and mediates ethanol-induced apoptosis in rat hepatocytes." American Journal of Physiology-Gastrointestinal and Liver Physiology 287, no. 3 (September 2004): G695—G705. http://dx.doi.org/10.1152/ajpgi.00415.2003.
Анотація:
Acute ethanol exposure induces oxidative stress and apoptosis in primary rat hepatocytes. Previous data indicate that the mitochondrial permeability transition (MPT) is essential for ethanol-induced apoptosis. However, the mechanism by which ethanol induces the MPT remains unclear. In this study, we investigated the role of Bax, a proapoptotic Bcl-2 family protein, in acute ethanol-induced hepatocyte apoptosis. We found that Bax translocates from the cytosol to mitochondria before mitochondrial cytochrome c release. Bax translocation was oxidative stress dependent. Mitochondrial Bax formed a protein complex with the mitochondrial voltage-dependent anion channel (VDAC). Prevention of Bax-VDAC interactions by a microinjection of anti-VDAC antibody effectively prevented hepatocyte apoptosis by ethanol. In conclusion, these data suggest that Bax translocation from the cytosol to mitochondria leads to the subsequent formation of a Bax-VDAC complex that plays a crucial role in acute ethanol-induced hepatocyte apoptosis.
50
Singh, R., G. Upadhyay, and MM Godbole. "Hypothyroidism alters mitochondrial morphology and induces release of apoptogenic proteins during rat cerebellar development." Journal of Endocrinology 176, no. 3 (March 1, 2003): 321–29. http://dx.doi.org/10.1677/joe.0.1760321.
Анотація:
Thyroid hormone (TH) deficiency leads to extensive apoptosis during cerebellar development, but the mechanism still remains unclear. Different signals also converge on mitochondria during apoptosis to induce the release of apoptogenic proteins that activate proteolytic cascade through specific enzymes called caspases. Here we studied the effect of hypothyroidism on alterations in mitochondrial structure and translocation of apoptogenic molecules during rat cerebellar development. Structural analysis of mitochondria was studied by electron microscopy. The translocation of apoptogenic molecules was analyzed by Western blotting. TH deficiency led to vacuolization, enlargement and decrease in the number of cristae. The majority of the proapoptotic molecule, Bax, was localized in mitochondria under hypothyroid conditions whereas a limited presence of Bax was detected in the euthyroid state. Translocation of cytochrome c, apoptosis-inducing factor (AIF) and second mitochondrial-derived activator of caspases (SMAC) from mitochondria to cytosol was detected primarily in early developmental stages in the hypothyroid condition. These experimental results demonstrate that TH maintains mitochondrial architecture and inhibits the release of apoptogenic molecules to prevent excess apoptosis during cerebellar development.