scholarly journals 82 EVALUATION OF CELL DEATH IN CRYOPRESERVED MOUSE EMBRYOS

2005 ◽  
Vol 17 (2) ◽  
pp. 191
Author(s):  
A.R.S. Coutinho ◽  
A.B. Nascimeto ◽  
C.M. Mendes ◽  
R. Simoes ◽  
C.F. Lucio ◽  
...  
Keyword(s):  
Cell Death ◽  
Liquid Nitrogen ◽  
Chromatin Condensation ◽  
Membrane Integrity ◽  
Embryonic Cell ◽  
Slow Freezing ◽  
Cell Membrane Integrity ◽  
Frozen Embryos ◽  
Mammalian Embryos ◽  
Cryopreserved Embryos

Cryopreservation of mammalian embryos is an important tool for the application of reproductive biotechnology. Recent evidence indicates that apoptosis may be important in determining the viability of cryopreserved embryos. Our goal was to detect apoptosis and characterize and quantify the embryonic cell death caused by cryopreservation. Mouse morulae were collected, selected, and separated into three groups: fresh, slow-freezing, and vitrification. In the slow-freezing procedure, embryos were exposed to 10% ethylene glycol (EG) for 10 min. After loading, the straws were placed into methanol at −7°C for 5 min, seeded and after 5 min cooled at 0.5°C/minute. After 10 minutes at −31°C, straws were plunged into and stored in liquid nitrogen. Slow-frozen straws were thawed in air for 10 s, and then immersed in a 25°C water bath for 20 s. Embryos were vitrified by exposing them to 10% and 20% EG for 5 min followed by 40% EG + 18% Ficoll + 10% sucrose (EFS) for 30 s and the 0.25-mL straws then plunged into and stored in liquid nitrogen. The vitrified straws were warmed by immersing them in 25°C water for 20 s. Cell membrane integrity was assessed by Hoechst and propidium iodide double staining (H/PI). Fresh and thawed embryos were scored (following IETS recommendations) and then fixed after 30 min in PBS + 10% FCS. Morphology and apoptosis were assessed with Haematoxylin-Eosin staining (HE) and by electron microscopy (MET). The number of Grade I embryos recovered after thawing was higher for slow-frozen embryos (61.5%) than vitrified embryos (29.5%). H/PI detected more membrane permeability in the vitrified embryos (69.7%), than in the slow-frozen (48.4%) or non-frozen (13.8%) groups (P < 0,05, Wilcoxon's test). Nuclear evaluation by HE revealed that vitrification and slow-freezing induced pyknosis and chromatin condensation. Mitotic pattern was observed in the fresh and slow-frozen group, but not in vitrification group suggesting that the embryos were either not randomly allocated to the groups or not-treated and fixed at the same age, or that vitrification changed the nuclear status of the embryos. HE staining revealed weakly staining cytoplasm and degenerated cells in the vitrification group (indicating oncosis), while in the slow-frozen group the presence of cytoplasmic condensation and eosinophilic structures indicated apoptosis. The ultrastructure examination confirmed the HE observations. In conclusion, the results demonstrated that staining with HE allows detection of oncosis and apoptosis in cryopreserved embryos. According to these data, vitrification caused more cellular injuries than slow-freezing, and oncosis was the predominant injury. It is important to point that specific molecular apoptosis tests must be performed to confirm these results. This work was supported by FAPESP 04/01252-4.

270 APOPTOSIS AND ONCOSIS ASSESSMENT IN CRYOPRESERVED MOUSE EMBRYOS

2006 ◽  
Vol 18 (2) ◽  
pp. 242
Author(s):  
M. E. O. A. Assumpção ◽  
A. R. S. Coutinho ◽  
W. B. Feitosa ◽  
C. M. Mendes ◽  
R. Simões ◽  
...  
Keyword(s):  
Cell Death ◽  
Liquid Nitrogen ◽  
Caspase 3 ◽  
Chromatin Condensation ◽  
Membrane Integrity ◽  
Water Bath ◽  
Slow Freezing ◽  
Control Group ◽  
Embryo Viability ◽  
Cryopreserved Embryos

Cryopreservation of mammalian embryos is an important tool for the application of reproductive biotechnology. Recent evidence indicates that apoptosis of cryopreserved embryos may be a negative factor for their viability. The aim of this study was to detect apoptosis and to characterize and quantify the embryonic cell death caused by cryopreservation. Mouse morulae were separated to be subjected to two cryopreservation protocols (slow freezing and vitrification) and a control group (fresh). In the slow-freezing procedure, embryos were exposed to 10% ethylene glycol (EG) for 10 min. Straws were placed in a methanol bath at -7�C until it reached -31�C and then plunged and stored in liquid nitrogen. The embryos were thawed in air for 10 s and in a 25�C water bath for 20 s. In the vitrification method, embryos were exposed to 10% and 20% EG for 5 min, followed by 40% EG + 18% Ficoll + 10% sucrose (EFS) for 30 s and then plunged and stored in liquid nitrogen. These embryos were thawed in a 25�C water bath for 20 s. For the cell death evaluation, cell membrane integrity from the fresh and cryopreserved embryos was assessed by Hoechst and propidium iodide (H/PI staining). Morphology and apoptosis were assessed by means of the haematoxylin-eosin staining (HE) and by electron microscopy (MET). To confirm apoptosis, 64 cryopreserved mouse morulae (34 submitted to slow freezing and 30 to vitrification) were used to evaluate Caspase-3 activity. The cryopreserved embryos were divided into experimental and control groups and incubated with Caspase-3 and buffer solution, respectively. Afterward, the embryos were incubated with rhodamine and the Caspase activity was determined under a fluorescence microscope. H/PI staining detected more membrane permeability in the vitrification (69.7%) than in the slow-freezing (48.4%) or fresh (13.8%) groups (P < 0.05; Wilcoxon's test). Nuclear evaluation by HE revealed that vitrification and slow freezing induced pyknosis and chromatin condensation. HE staining revealed weakly staining cytoplasm and degenerated cells in the vitrification group (indicating oncosis), whereas in the slow-freezing the presence of cytoplasmic condensation and eosinophilic structures indicating apoptosis were observed. MET examination of the ultrastructure confirmed the HE results. The Caspase-3 activity showed a fluorescence increase in both experimental groups compared with the control group. In conclusion, staining with HE allows detection of oncosis and apoptosis in cryopreserved embryos. Regarding the cryopreservation techniques, both slow freezing and vitrification showed oncosis and apoptosis injuries. However, in this experiment vitrification caused more cellular injuries, with less embryo viability, than slow freezing. This work was supported by FAPESP 04/01252-4 and CAPES.

Quercetin in attenuation of ischemic/reperfusion injury: A review

2020 ◽  
Vol 13 ◽  
Author(s):  
Milad Ashrafizadeh ◽  
Saeed Samarghandian ◽  
Kiavash Hushmandi ◽  
Amirhossein Zabolian ◽  
Md Shahinozzaman ◽  
...  
Keyword(s):  
Cell Death ◽  
Cell Membrane ◽  
Blood Supply ◽  
Apoptotic Cell ◽  
Ischemia Reperfusion ◽  
Membrane Integrity ◽  
Therapeutic Effects ◽  
Molecular Pathways ◽  
Cell Membrane Integrity ◽  
Cell Membrane Disruption

Background: Ischemia/reperfusion (I/R) injury is a serious pathologic event that occurs due to restriction in blood supply to an organ, followed by hypoxia. This condition leads to enhanced levels of pro-inflammatory cytokines such as IL-6 and TNF-, and stimulation of oxidative stress via enhancing reactive oxygen species (ROS) levels. Upon reperfusion, blood supply increases, but it deteriorates condition, and leads to generation of ROS, cell membrane disruption and finally, cell death. Plant derived-natural compounds are well-known due to their excellent antioxidant and anti-inflammatory activities. Quercetin is a flavonoid exclusively found in different vegetables, herbs, and fruits. This naturally occurring compound possesses different pharmacological activities making it appropriate option in disease therapy. Quercetin can also demonstrate therapeutic effects via affecting molecular pathways such as NF-B, PI3K/Akt and so on. Methods: In the present review, we demonstrate that quercetin administration is beneficial in ameliorating I/R injury via reducing ROS levels, inhibition of inflammation, and affecting molecular pathways such as TLR4/NF-B, MAPK and so on. Results and conclusion: Quercetin can improve cell membrane integrity via decreasing lipid peroxidation. Apoptotic cell death is inhibited by quercetin via down-regulation of Bax, and caspases, and upregulation of Bcl-2. Quercetin is able to modulate autophagy (inhibition/induction) in decreasing I/R injury. Nanoparticles have been applied for delivery of quercetin, enhancing its bioavailability and efficacy in alleviation of I/R injury. Noteworthy, clinical trials have also confirmed the capability of quercetin in reducing I/R injury.

scholarly journals Neurotoxic Effect of Flavonol Myricetin in the Presence of Excess Copper

Molecules ◽  
2021 ◽  
Vol 26 (4) ◽  
pp. 845
Author(s):  
Anja Sadžak ◽  
Ignacija Vlašić ◽  
Zoran Kiralj ◽  
Marijana Batarelo ◽  
Nada Oršolić ◽  
...  
Keyword(s):  
Cell Death ◽  
Intracellular Signaling ◽  
Chromatin Condensation ◽  
Membrane Integrity ◽  
Toxic Effects ◽  
Trypan Blue Exclusion ◽  
Atp Production ◽  
Mtt Method ◽  
Biophysical Approach ◽  
Induced Changes

Oxidative stress (OS) induced by the disturbed homeostasis of metal ions is one of the pivotal factors contributing to neurodegeneration. The aim of the present study was to investigate the effects of flavonoid myricetin on copper-induced toxicity in neuroblastoma SH-SY5Y cells. As determined by the MTT method, trypan blue exclusion assay and measurement of ATP production, myricetin heightened the toxic effects of copper and exacerbated cell death. It also increased copper-induced generation of reactive oxygen species, indicating the prooxidative nature of its action. Furthermore, myricetin provoked chromatin condensation and loss of membrane integrity without caspase-3 activation, suggesting the activation of both caspase-independent programmed cell death and necrosis. At the protein level, myricetin-induced upregulation of PARP-1 and decreased expression of Bcl-2, whereas copper-induced changes in the expression of p53, p73, Bax and NME1 were not further affected by myricetin. Inhibitors of ERK1/2 and JNK kinases, protein kinase A and L-type calcium channels exacerbated the toxic effects of myricetin, indicating the involvement of intracellular signaling pathways in cell death. We also employed atomic force microscopy (AFM) to evaluate the morphological and mechanical properties of SH-SY5Y cells at the nanoscale. Consistent with the cellular and molecular methods, this biophysical approach also revealed a myricetin-induced increase in cell surface roughness and reduced elasticity. Taken together, we demonstrated the adverse effects of myricetin, pointing out that caution is required when considering powerful antioxidants for adjuvant therapy in copper-related neurodegeneration.

132 SUCCESSFUL EMBRYO TRANSFER OF IN VIVO-PRODUCED RED DEER (CERVUS ELAPHUS) EMBRYOS AFTER CRYOPRESERVATION BY SLOW FREEZING OR VITRIFICATION

2007 ◽  
Vol 19 (1) ◽  
pp. 183
Author(s):  
J. P. Soler ◽  
G. G. Kaiser ◽  
N. Mucci ◽  
L. B. Ferre ◽  
R. H. Alberio
Keyword(s):  
Liquid Nitrogen ◽  
Embryo Transfer ◽  
Cervus Elaphus ◽  
Red Deer ◽  
Slow Freezing ◽  
Alternative Methods ◽  
Embryo Cryopreservation ◽  
Chi Square ◽  
Cryopreserved Embryos

Multiple ovulation and embryo transfer (MOET) programs for red deer (Cervus elaphus) have been established commercially over the last decade, with embryo cryopreservation being a related practice necessary to enhance the use of valuable genetic information. The aim of this work was to establish alternative methods for red deer embryo cryopreservation by using slow freezing with ethylene glycol (SF–EG) and vitrification by open pulled straw (OPS) methods. After surgical flushing of 18 superstimulated donors, 54 transferable embryos were recovered; 28 were transferred fresh to synchronized recipients and the others were cryopreserved by SF–EG (n = 11) or OPS (n = 15), respectively thawed or warmed, and transferred to recipients. Fresh embryos were maintained in Dulbecco's PBS + 20% cow serum (holding medium, HM) until transfer (maximum 3 h after collection). SF–EG cryopreserved embryos were suspended in HM + 1.78 M EG + 0.1 M sucrose + 4 mg mL−1 BSA. After a 10-min equilibration, embryos were loaded individually into 0.25-mL plastic straws and placed into a −7°C methanol bath chamber. After seeding (5 min later), the straws were cooled from −7 to −35°C at a rate of 0.5°C min. Straws were plunged into and stored in liquid nitrogen. Thawing was performed by placing the straws in a 30°C water bath for 30 s; their contents were drained into HM until transfer. Embryos were vitrified using the OPS method with minor modifications. They were first incubated in HM + 1.78 M EG + 1.3 M DMSO for 3 min and then transferred for 25 s into a vitrification solution of HM + 3.56 M EG + 2.6 M DMSO + 0.5 M sucrose. Each embryo was loaded by touching a 1-µL drop with the straw, which was immediately submerged into and stored in liquid nitrogen. Warming was done by placing the narrow end of the straws into HM + 0.25 M sucrose for 5 min. Embryos were then transferred into HM + 0.15 M sucrose for 5 min and finally to HM until transfer. Both types of cryopreserved embryos were transferred a few hours after collection, immediately after thawing or warming. Before embryo transfer, the presence of corpus luteum (CL) of recipients was confirmed by laparoscopic examination. Each embryo was surgically transferred into the apical extreme of the uterine horn ipsilateral to the CL of one recipient. Pregnancy was determined by ultrasonography 41 days after embryo transfer. The pregnancy rate between groups was compared with the chi-square test (P &lt; 0.05). No statistical differences were found between groups (Table 1). Our results show that both vitrification and slow freezing methods with EG are suitable to cryopreserve red deer embryos. Table 1. Pregnancy rates in recipient hinds after transfer of fresh, vitrified, or frozen red deer embryos

scholarly journals Slow freezing versus vitrification for the cryopreservation of zebrafish (Danio rerio) ovarian tissue

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Lis S. Marques ◽  
Ana A. N. Fossati ◽  
Rômulo B. Rodrigues ◽  
Helen T. Da Rosa ◽  
Aryele P. Izaguirry ◽  
...  
Keyword(s):  
Plasma Membranes ◽  
Ovarian Tissue ◽  
Membrane Integrity ◽  
Egg Yolk ◽  
Slow Freezing ◽  
Mitochondrial Activity ◽  
Trypan Blue Exclusion ◽  
Cell Membrane Integrity ◽  
Cell Plasma ◽  
Cryopreservation Method

Abstract The aim of the present study was to compare the efficiency of vitrification and slow freezing techniques for the cryopreservation of zebrafish ovarian tissue containing immature follicles. In Experiment 1, assessment of cell membrane integrity by trypan blue exclusion staining was used to select the best cryoprotectant solution for each cryopreservation method. Primary growth (PG) oocytes showed the best percentage of membrane integrity (63.5 ± 2.99%) when SF4 solution (2 M methanol + 0.1 M trehalose + 10% egg yolk solution) was employed. The vitrification solution, which presented the highest membrane integrity (V2; 1.5 M methanol + 5.5 M Me2SO + 0.5 M sucrose + 10% egg yolk solution) was selected for Experiment 2. Experiment 2 aimed to compare the vitrification and slow freezing techniques in the following parameters: morphology, oxidative stress, mitochondrial activity, and DNA damage. Frozen ovarian tissue showed higher ROS levels and lower mitochondrial activity than vitrified ovarian tissue. Ultrastructural observations of frozen PG oocytes showed rupture of the plasma membrane, loss of intracellular contents and a large number of damaged mitochondria, while vitrified PG oocytes had intact mitochondria and cell plasma membranes. We conclude that vitrification may be more effective than slow freezing for the cryopreservation of zebrafish ovarian tissue.

scholarly journals Dehydroabietic Acid Derivative QC4 Induces Gastric Cancer Cell Death via Oncosis and Apoptosis

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Dongjun Luo ◽  
Qing Ni ◽  
Anlai Ji ◽  
Wen Gu ◽  
Junhua Wu ◽  
...  
Keyword(s):  
Gastric Cancer ◽  
Cell Death ◽  
Cancer Cells ◽  
Cytotoxic Effect ◽  
Membrane Integrity ◽  
Dehydroabietic Acid ◽  
Protein Cleavage ◽  
Gastric Cancer Cells ◽  
Cell Membrane Integrity ◽  
Cancer Cell Death

Aim. QC4 is the derivative of rosin’s main components dehydroabietic acid (DHA). We investigated the cytotoxic effect of QC4 on gastric cancer cells and revealed the mechanisms beneath the induction of cell death.Methods. The cytotoxic effect of QC4 on gastric cancer cells was evaluated by CCK-8 assay and flow cytometry. The underlying mechanisms were tested by administration of cell death related inhibitors and detection of apoptotic and oncosis related proteins. Cytomembrane integrity and organelles damage were confirmed by lactate dehydrogenase (LDH) leakage assay, mitochondrial function test, and cytosolic free Ca2+concentration detection.Results. QC4 inhibited cell proliferation dose- and time-dependently and destroyed cell membrane integrity, activated calpain-1 autolysis, and induced apoptotic protein cleavage in gastric cancer cells. The detection of decreased ATP and mitochondrial membrane potential, ROS accumulation, and cytosolic free Ca2+elevation confirmed organelles damage in QC4-treated gastric cancer cells.Conclusions. DHA derivative QC4 induced the damage of cytomembrane and organelles which finally lead to oncosis and apoptosis in gastric cancer cells. Therefore, as a derivative of plant derived small molecule DHA, QC4 might become a promising agent in gastric cancer therapy.

Induction by arsenate of cell-type-specific cytotoxic effects in nerve and hepatoma cells

2017 ◽  
Vol 36 (12) ◽  
pp. 1256-1269 ◽  
Author(s):  
Wafa Kharroubi ◽  
Thomas Nury ◽  
Samia Haj Ahmed ◽  
Pierre Andreoletti ◽  
Rachid Sakly ◽  
...  
Keyword(s):  
Cell Death ◽  
Trypan Blue ◽  
Membrane Integrity ◽  
Cell Types ◽  
Hepatoma Cells ◽  
Cell Counting ◽  
Cell Type ◽  
Human Hepatoma Cells ◽  
Cell Membrane Integrity ◽  
The Impact

The aim of the study was to compare the effect of sodium arsenate (AsV) on two different cell types: 158N murine oligodendrocytes and HepG2 human hepatoma cells. Exposure of 158N cells to AsV (0.1–400 µM; 48 h) induced a biphasic cytoxic effect defined as hormesis. Thus, low concentrations of AsV stimulate cell proliferation, as shown by phase-contrast microscopy, cell counting with trypan blue, and crystal violet assay, whereas high concentrations induce cell death associated with a loss of cell adhesion. These side effects were confirmed by staining with propidium iodide and cell cycle analysis, characterized by the presence of a subG1 peak, a criterion of apoptosis. The effects of AsV on mitochondrial function, as determined by the 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium (MTT) assay, the measurement of mitochondrial transmembrane potential with 3,3′-dihexyloxacarbocyanine iodide, and the rate of mitochondrial adenosine triphosphate confirm the impact of AsV on the mitochondria. In contrast to 158N cells, HepG2 cells were susceptible to all AsV concentrations as shown by microscopic observations, by counting with trypan blue. However, no alteration is noted in the cell membrane integrity, which indicated an apoptotic mode of cell death, and this side effect is confirmed by the cycle analysis, which revealed a subG1 peak. Of note, there was a loss of MTT, suggesting that AsV induces mitochondrial complex II dysfunction. Altogether, our data show that the cytotoxic characteristics of AsV depend on the cell type considered.

scholarly journals Racemoside A, an anti-leishmanial, water-soluble, natural steroidal saponin, induces programmed cell death in Leishmania donovani

2007 ◽  
Vol 56 (9) ◽  
pp. 1196-1204 ◽  
Author(s):  
Avijit Dutta ◽  
Angana Ghoshal ◽  
Debayan Mandal ◽  
Nirup B. Mondal ◽  
Sukdeb Banerjee ◽  
...  
Keyword(s):  
Cell Death ◽  
Programmed Cell Death ◽  
Leishmania Donovani ◽  
Chromatin Condensation ◽  
Membrane Integrity ◽  
Water Soluble ◽  
Asparagus Racemosus ◽  
Steroidal Saponin ◽  
Significant Activity ◽  
Major Health Problem

Leishmaniasis remains a major health problem of the tropical and subtropical world. The visceral form causes the most fatalities if left untreated. Dramatic increases in the rates of infection and drug resistance and the non-availability of safe vaccines have highlighted the need for identification of novel and inexpensive anti-leishmanial agents. This study reports that racemoside A, a water-soluble steroidal saponin purified from the fruits of Asparagus racemosus, is a potent anti-leishmanial molecule effective against antimonial-sensitive (strain AG83) and -unresponsive (strain GE1F8R) Leishmania donovani promastigotes, with IC50 values of 1.15 and 1.31 μg ml−1, respectively. Incubation of promastigotes with racemoside A caused morphological alterations including cell shrinkage, an aflagellated ovoid shape and chromatin condensation. This compound exerts its leishmanicidal effect through the induction of programmed cell death mediated by the loss of plasma membrane integrity as detected by binding of annexin V and propidium iodide, loss of mitochondrial membrane potential culminating in cell-cycle arrest at the sub-G0/G1 phase, and DNA nicking shown by deoxynucleotidyltransferase-mediated dUTP end labelling (TUNEL). Racemoside A also showed significant activity against intracellular amastigotes of AG83 and GE1F8R at a 7–8-fold lower dose, with IC50 values of 0.17 and 0.16 μg ml−1, respectively, and was non-toxic to murine peritoneal macrophages up to a concentration of 10 μg ml−1. Hence, racemoside A is a potent anti-leishmanial agent that merits further pharmacological investigation.

scholarly journals The Calcineurin Pathway Inhibitor Tacrolimus Enhances the In Vitro Activity of Azoles against Mucorales via Apoptosis

2013 ◽  
Vol 12 (9) ◽  
pp. 1225-1234 ◽  
Author(s):  
F. Shirazi ◽  
D. P. Kontoyiannis
Keyword(s):  
Cell Death ◽  
Dna Fragmentation ◽  
Rhizopus Oryzae ◽  
Apoptotic Cell ◽  
Chromatin Condensation ◽  
Membrane Integrity ◽  
Ros Generation ◽  
Content Type ◽  
Intracellular Ca ◽  
Calcineurin Pathway

ABSTRACT The calcineurin pathway regulates antifungal drug resistance and the virulence of several major human-pathogenic fungi, including the recalcitrant Mucorales . We hypothesized that the fungistatic triazoles posaconazole (PCZ) and itraconazole (ICZ) become fungicidal in the setting of the calcineurin inhibitor tacrolimus (TCR) and that such an effect is mediated through apoptosis. Fungicidal activity and apoptosis were studied using standard microbiological techniques and hyphal metabolic and vital dye reduction assays at 37°C in RPMI 1640. Apoptosis was characterized by detecting intracellular Ca 2+ , phosphatidylserine (PS) externalization, DNA fragmentation, plasma membrane integrity, chromatin condensation, reactive oxygen species (ROS) generation, caspase-like activity, ATP, and cytochrome c release. MICs for PCZ and ICZ alone were significantly higher (8 to 128 μg/ml) than those of PCZ or ICZ plus TCR (0.25 to 4 μg/ml) for Rhizopus oryzae , Cunninghamella bertholletiae , and Mucor circinelloides . Both PCZ and ICZ in combination with TCR became fungicidal, and their activity was mediated through increased apoptotic cell death of R. oryzae (10 to 50%), C. bertholletiae (5 to 50%), and M. circinelloides (5 to 55%) germlings, with morphological apoptotic changes characterized by externalization of PS, nuclear condensation, and DNA fragmentation. Moreover, activation of the caspase-like activity was correlated with cell death induced by TCR plus PCZ or ICZ. These changes correlated with elevated intracellular Ca 2+ and ROS levels and disturbance of mitochondrial potential. We found that PCZ or ICZ in combination with TCR renders Mucorales sensitive to triazoles via apoptotic death. These observations could serve as a new paradigm for the development of new therapeutic strategies.

scholarly journals The Drosophila TNF Eiger activates caspase-dependent necrosis when apoptosis is blocked

2018 ◽  
Author(s):  
Mingli Li ◽  
Yun Fan
Keyword(s):  
Cell Death ◽  
Apoptotic Cell ◽  
Membrane Integrity ◽  
Apoptotic Cell Death ◽  
Dual Roles ◽  
Developmental Defects ◽  
Cell Membrane Integrity ◽  
Effector Caspases ◽  
Necrosis Factor ◽  
Cellular Organelles

AbstractEiger (Egr), the homolog of the mammalian tumor-necrosis factor (TNF), is the ligand of the c-Jun N-terminal kinase (JNK) stress response signaling pathway in Drosophila. Although expression of Egr frequently leads to apoptosis, it has also been implicated in activation of non-apoptotic cell death. However, it is not yet clear how Egr can induce both apoptosis and non-apoptotic cell death, and if so, how such processes are coordinated. Here, we show that expression of Egr in the developing Drosophila eye induces apoptosis and non-apoptotic developmental defects, both of which are JNK-dependent. Intriguingly, when apoptotic effector caspases DrICE and Dcp-1 are defective or inhibited, expression of Egr induces necrosis characterized by loss of cell membrane integrity, translucent cytoplasm and aggregation of cellular organelles. Surprisingly, the induction of necrosis depends on the catalytic activity of the initiator caspase Dronc and the input from JNK signaling independently of their roles in apoptosis. Therefore, similar to the mammalian caspase-8, caspases in Drosophila also have dual roles in promoting TNF-mediated apoptosis and inhibiting necrosis.

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