scholarly journals Bax Is Activated during Rotavirus-Induced Apoptosis through the Mitochondrial Pathway

2007 ◽  
Vol 81 (9) ◽  
pp. 4457-4464 ◽  
Author(s):  
Sandra Martin-Latil ◽  
Laurence Mousson ◽  
Arnaud Autret ◽  
Florence Colbère-Garapin ◽  
Bruno Blondel
Keyword(s):  
Mitochondrial Pathway ◽  
Cellular Level ◽  
Viral Gastroenteritis ◽  
Small Interfering Rnas ◽  
Apoptotic Pathway ◽  
Osmotic Diarrhea ◽  
Dividing Cells ◽  
Intestinal Functions ◽  
Infected Cells ◽  
Induced Apoptosis

ABSTRACT Rotaviruses are the leading cause of infantile viral gastroenteritis worldwide. Mature enterocytes of the small intestine infected by rotavirus undergo apoptosis, and their replacement by less differentiated dividing cells probably leads to defective absorptive function of the intestinal epithelium, which, in turn, contributes to osmotic diarrhea and rotavirus pathogenesis. Here we show that infection of MA104 cells by the simian rhesus rotavirus strain RRV induced caspase-3 activation, DNA fragmentation, and cleavage of poly(ADP-ribose) polymerase; all three phenomena are features of apoptosis. RRV induced the release of cytochrome c from mitochondria to the cytosol, indicating that the mitochondrial apoptotic pathway was activated. RRV infection of MA104 cells activated Bax, a proapoptotic member of the Bcl-2 family, as revealed by its conformational change. Most importantly, Bax-specific small interfering RNAs partially inhibited cytochrome c release in RRV-infected cells. Thus, mitochondrial dysfunction induced by rotavirus is Bax dependent. Apoptosis presumably leads to impaired intestinal functions, so our findings contribute to improving our understanding of rotavirus pathogenesis at the cellular level.

scholarly journals Role of the Mitochondrial Signaling Pathway in Murine Coronavirus-Induced Oligodendrocyte Apoptosis

2006 ◽  
Vol 80 (1) ◽  
pp. 395-403 ◽  
Author(s):  
Yin Liu ◽  
Yinghui Pu ◽  
Xuming Zhang
Keyword(s):  
Hepatitis Virus ◽  
Mitochondrial Pathway ◽  
Caspase 8 ◽  
Caspase 9 ◽  
Apoptotic Pathway ◽  
Antiapoptotic Proteins ◽  
Mitochondrial Signaling ◽  
Drastic Increase ◽  
Infected Cells

ABSTRACT A previous study demonstrated that infection of rat oligodendrocytes by mouse hepatitis virus (MHV) resulted in apoptosis, which is caspase dependent (Y. Liu, Y. Cai, and X. Zhang, J. Virol. 77:11952-11963, 2003). Here we determined the involvement of the mitochondrial pathway in MHV-induced oligodendrocyte apoptosis. We found that caspase-9 activity was 12-fold higher in virus-infected cells than in mock-infected cells at 24 h postinfection (p.i.). Pretreatment of cells with a caspase-9 inhibitor completely blocked caspase-9 activation and partially inhibited the apoptosis mediated by MHV infection. Analyses of cytochrome c release further revealed an activation of the mitochondrial apoptotic pathway. Stable overexpression of the two antiapoptotic proteins Bcl-2 and Bcl-xL significantly, though only partially, blocked apoptosis, suggesting that activation of the mitochondrial pathway is partially responsible for the apoptosis. To identify upstream signals, we determined caspase-8 activity, cleavage of Bid, and expression of Bax and Bad by Western blotting. We found a drastic increase in caspase-8 activity and cleavage of Bid at 24 h p.i. in virus-infected cells, suggesting that Bid may serve as a messenger to relay the signals from caspase-8 to mitochondria. However, treatment with a caspase-8 inhibitor only slightly blocked cytochrome c release from the mitochondria. Furthermore, we found that Bax but not Bad was significantly increased at 12 h p.i. in cells infected with both live and UV-inactivated viruses and that Bax activation was partially blocked by treatment with the caspase-8 inhibitor. These results thus establish the involvement of the mitochondrial pathway in MHV-induced oligodendrocyte apoptosis.

scholarly journals Rotavirus NSP4 Induces a Novel Vesicular Compartment Regulated by Calcium and Associated with Viroplasms

2006 ◽  
Vol 80 (12) ◽  
pp. 6061-6071 ◽  
Author(s):  
Z. Berkova ◽  
S. E. Crawford ◽  
G. Trugnan ◽  
T. Yoshimori ◽  
A. P. Morris ◽  
...  
Keyword(s):  
Virus Replication ◽  
Fluorescent Protein ◽  
Nonstructural Protein ◽  
Brefeldin A ◽  
Viral Gastroenteritis ◽  
Small Interfering Rnas ◽  
Hek 293 ◽  
C Terminus ◽  
Infected Cells ◽  
Green Fluorescent

ABSTRACT Rotavirus is a major cause of infantile viral gastroenteritis. Rotavirus nonstructural protein 4 (NSP4) has pleiotropic properties and functions in viral morphogenesis as well as pathogenesis. Recent reports show that the inhibition of NSP4 expression by small interfering RNAs leads to alteration of the production and distribution of other viral proteins and mRNA synthesis, suggesting that NSP4 also affects virus replication by unknown mechanisms. This report describes studies aimed at correlating the localization of intracellular NSP4 in cells with its functions. To be able to follow the localization of NSP4, we fused the C terminus of full-length NSP4 with the enhanced green fluorescent protein (EGFP) and expressed this fusion protein inducibly in a HEK 293-based cell line to avoid possible cytotoxicity. NSP4-EGFP was initially localized in the endoplasmic reticulum (ER) as documented by Endo H-sensitive glycosylation and colocalization with ER marker proteins. Only a small fraction of NSP4-EGFP colocalized with the ER-Golgi intermediate compartment (ERGIC) marker ERGIC-53. NSP4-EGFP did not enter the Golgi apparatus, in agreement with the Endo H sensitivity and a previous report that secretion of an NSP4 cleavage product generated in rotavirus-infected cells is not inhibited by brefeldin A. A significant population of expressed NSP4-EGFP was distributed in novel vesicular structures throughout the cytoplasm, not colocalizing with ER, ERGIC, Golgi, endosomal, or lysosomal markers, thus diverging from known biosynthetic pathways. The appearance of vesicular NSP4-EGFP was dependent on intracellular calcium levels, and vesicular NSP4-EGFP colocalized with the autophagosomal marker LC3. In rotavirus-infected cells, NSP4 colocalized with LC3 in cap-like structures associated with viroplasms, the site of nascent viral RNA replication, suggesting a possible new mechanism for the involvement of NSP4 in virus replication.

scholarly journals IκB Kinase Subunits α and γ Are Required for Activation of NF-κB and Induction of Apoptosis by Mammalian Reovirus

2006 ◽  
Vol 81 (3) ◽  
pp. 1360-1371 ◽  
Author(s):  
Mark W. Hansberger ◽  
Jacquelyn A. Campbell ◽  
Pranav Danthi ◽  
Pia Arrate ◽  
Kevin N. Pennington ◽  
...  
Keyword(s):  
Nuclear Translocation ◽  
Cultured Cells ◽  
Inhibitory Effect ◽  
Regulatory Subunit ◽  
Small Interfering Rnas ◽  
Gene Encoding ◽  
Iκb Kinase ◽  
Infected Cells ◽  
Induced Apoptosis

ABSTRACT Reoviruses induce apoptosis both in cultured cells and in vivo. Apoptosis plays a major role in the pathogenesis of reovirus encephalitis and myocarditis in infected mice. Reovirus-induced apoptosis is dependent on the activation of transcription factor NF-κB and downstream cellular genes. To better understand the mechanism of NF-κB activation by reovirus, NF-κB signaling intermediates under reovirus control were investigated at the level of Rel, IκB, and IκB kinase (IKK) proteins. We found that reovirus infection leads initially to nuclear translocation of p50 and RelA, followed by delayed mobilization of c-Rel and p52. This biphasic pattern of Rel protein activation is associated with the degradation of the NF-κB inhibitor IκBα but not the structurally related inhibitors IκBβ or IκBε. Using IKK subunit-specific small interfering RNAs and cells deficient in individual IKK subunits, we demonstrate that IKKα but not IKKβ is required for reovirus-induced NF-κB activation and apoptosis. Despite the preferential usage of IKKα, both NF-κB activation and apoptosis were attenuated in cells lacking IKKγ/Nemo, an essential regulatory subunit of IKKβ. Moreover, deletion of the gene encoding NF-κB-inducing kinase, which is known to modulate IKKα function, had no inhibitory effect on either response in reovirus-infected cells. Collectively, these findings indicate a novel pathway of NF-κB/Rel activation involving IKKα and IKKγ/Nemo, which together mediate the expression of downstream proapoptotic genes in reovirus-infected cells.

scholarly journals Diosgenin Induces Apoptosis in HepG2 Cells through Generation of Reactive Oxygen Species and Mitochondrial Pathway

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Dae Sung Kim ◽  
Byoung Kook Jeon ◽  
Young Eun Lee ◽  
Won Hong Woo ◽  
Yeun Ja Mun
Keyword(s):  
P38 Mapk ◽  
Hepg2 Cells ◽  
Caspase 3 ◽  
Mitochondrial Pathway ◽  
Carcinoma Cells ◽  
Dapi Staining ◽  
Apoptotic Pathway ◽  
Induced Apoptosis ◽  
Dose Dependent ◽  
Human Hepatocellular Carcinoma Cells

Diosgenin, a naturally occurring steroid saponin found abundantly in legumes and yams, is a precursor of various synthetic steroidal drugs. Diosgenin is studied for the mechanism of its action in apoptotic pathway in human hepatocellular carcinoma cells. Based on DAPI staining, diosgenin-treated cells manifested nuclear shrinkage, condensation, and fragmentation. Treatment of HepG2 cells with 40 μM diosgenin resulted in activation of the caspase-3, -8, -9 and cleavage of poly-ADP-ribose polymerase (PARP) and the release of cytochromec.In the upstream, diosgenin increased the expression of Bax, decreased the expression of Bid and Bcl-2, and augmented the Bax/Bcl-2 ratio. Diosgenin-induced, dose-dependent induction of apoptosis was accompanied by sustained phosphorylation of JNK, p38 MAPK and apoptosis signal-regulating kinase (ASK)-1, as well as generation of the ROS. NAC administration, a scavenger of ROS, reversed diosgene-induced cell death. These results suggest that diosgenin-induced apoptosis in HepG2 cells through Bcl-2 protein family-mediated mitochndria/caspase-3-dependent pathway. Also, diosgenin strongly generated ROS and this oxidative stress might induce apoptosis through activation of ASK1, which are critical upstream signals for JNK/p38 MAPK activation in HepG2 cancer cells.

scholarly journals Bak and Bax Function To Limit Adenovirus Replication through Apoptosis Induction

2002 ◽  
Vol 76 (9) ◽  
pp. 4547-4558 ◽  
Author(s):  
Andrea Cuconati ◽  
Kurt Degenhardt ◽  
Ramya Sundararajan ◽  
Alan Anschel ◽  
Eileen White
Keyword(s):  
Cellular Level ◽  
Productive Infection ◽  
Apoptosis Induction ◽  
Wild Type ◽  
Caspase 9 ◽  
Proliferation And Apoptosis ◽  
Infected Cells ◽  
Induced Apoptosis ◽  
Induced Changes ◽  
Adenovirus Replication

ABSTRACT Adenovirus infection and expression of E1A induces both proliferation and apoptosis, the latter of which is blocked by the adenovirus Bcl-2 homologue E1B 19K. The mechanism of apoptosis induction and the role that it plays in productive infection are not known. Unlike apoptosis mediated by death receptors, infection with proapoptotic E1B 19K mutant viruses did not induce cleavage of Bid but nonetheless induced changes in Bak and Bax conformation, Bak-Bax interaction, caspase 9 and 3 activation, and apoptosis. In wild-type-adenovirus-infected cells, in which E1B 19K inhibits apoptosis, E1B 19K was bound to Bak, precluding Bak-Bax interaction and changes in Bax conformation. Infection with E1B 19K mutant viruses induced apoptosis in wild-type and Bax- or Bak-deficient baby mouse kidney cells but not in those deficient for both Bax and Bak. Furthermore, Bax and Bak deficiency dramatically increased E1A expression and virus replication. Thus, Bax- and Bak-mediated apoptosis severely limits adenoviral replication, demonstrating that Bax and Bak function as an antiviral response at the cellular level.

scholarly journals The Major Apoptotic Pathway Activated and Suppressed by Poliovirus

2003 ◽  
Vol 77 (1) ◽  
pp. 45-56 ◽  
Author(s):  
George A. Belov ◽  
Lyudmila I. Romanova ◽  
Elena A. Tolskaya ◽  
Marina S. Kolesnikova ◽  
Yuri A. Lazebnik ◽  
...  
Keyword(s):  
Program Implementation ◽  
Caspase 3 ◽  
Chromatin Condensation ◽  
Productive Infection ◽  
Caspase 9 ◽  
Apoptotic Pathway ◽  
Poliovirus Infection ◽  
Proapoptotic Protein ◽  
Infected Cells ◽  
Induced Apoptosis

ABSTRACT Cells respond to poliovirus infection by switching on the apoptotic program, implementation of which is usually suppressed by viral antiapoptotic functions. We show here that poliovirus infection of HeLa cells or derivatives of MCF-7 cells was accompanied by the efflux of cytochrome c from mitochondria. This efflux occurred during both abortive infection (e.g., interrupted by guanidine-HCl and ending with apoptosis) and productive infection (leading to cytopathic effect). The former type of infection, but not the latter, was accompanied by truncation of the proapoptotic protein Bid. The virus-triggered cytochrome c efflux was suppressed by overexpression of Bcl-2. Both abortive and productive infections also resulted in a decreased level of procaspase-9, as revealed by Western blotting. In the former case, this decrease was accompanied by the accumulation of a protein with the electrophoretic mobility of active caspase-9. In contrast, in the productively infected cells, the latter protein was absent but caspase-9-related polypeptides with altered mobility could be detected. Both caspase-9 and caspase-3 were shown to be essential for the development of such hallmarks of virus-induced apoptosis as chromatin condensation, DNA degradation, and nuclear fragmentation. These and some other results suggest the following scenario. Poliovirus infection activates the apoptotic pathway, involving mitochondrial damage, cytochrome c efflux, and consecutive activation of caspase-9 and caspase-3. The apoptotic signal appears to be amplified by a loop which includes secondary processing of Bid. The implementation of the apoptotic program in productively infected cells may be suppressed, however, by the viral antiapoptotic functions, which act at a step(s) downstream of the cytochrome c efflux. The suppression appears to be caused, at least in part, by aberrant processing and degradation of procaspase-9.

scholarly journals LCT-3d Induces Oxidative Stress-Mediated Apoptosis by Upregulating Death Receptor 5 in Gastric Cancer Cells

2021 ◽  
Vol 11 ◽  
Author(s):  
Menglin Wang ◽  
Xinxin Wu ◽  
Lu Yu ◽  
Zi-yun Hu ◽  
Xiaobo Li ◽  
...  
Keyword(s):  
Gastric Cancer ◽  
Cancer Cells ◽  
Cell Apoptosis ◽  
Death Receptor ◽  
Mitochondrial Pathway ◽  
Related Factor ◽  
Death Receptor 5 ◽  
Gastric Cancer Cells ◽  
Apoptotic Pathway ◽  
Induced Apoptosis

Gastric cancer is a global health problem. In this study, we investigate the role of a novel Indole derivative, named LCT-3d, in inhibiting the growth of gastric cancer cells by MTT assay. The Western blotting results showed that LCT-3d modulated the mitochondrial-related proteins and Cleaved-Caspases 3/9, to induce cell apoptosis. The up-regulation of Death receptor 5 (DR5) in MGC803 cells was observed with LCT-3d treatment. Knockdown of DR5 on MGC803 cells partially reversed the LCT-3d-induced mitochondrial apoptosis. The level of Reactive Oxygen Species (ROS) in MGC803 cells was increased with LCT-3d treatment and could be blocked with the pretreatment of the ROS inhibitor N-Acetylcysteine (NAC). The results demonstrate that the elevating ROS can up-regulate the expression of DR5, resulting in apoptosis via mitochondrial pathway. Although the nuclear factor erythroid-2 related factor 2 (Nrf2) pathway served an important role in protecting gastric cancer cells against the injury of ROS, it can’t reverse LCT-3d-induced cell apoptosis. Taken together, our study showed that LCT-3d induced apoptosis via DR5-mediated mitochondrial apoptotic pathway in gastric cancer cells. LCT-3d could be a novel lead compound for development of anti-cancer activity in gastric cancer.

scholarly journals HOXA5-Induced Apoptosis in Breast Cancer Cells Is Mediated by Caspases 2 and 8

2004 ◽  
Vol 24 (2) ◽  
pp. 924-935 ◽  
Author(s):  
Hexin Chen ◽  
Seung Chung ◽  
Saraswati Sukumar
Keyword(s):  
Breast Cancer ◽  
Cell Death ◽  
Target Genes ◽  
Small Interfering Rnas ◽  
Mcf7 Cells ◽  
Apoptotic Pathway ◽  
Apoptotic Pathways ◽  
Caspase 2 ◽  
Induced Apoptosis ◽  
Specific Inhibitors

ABSTRACT HOXA5 is a transcriptional factor whose expression is lost in more than 60% of breast carcinomas. Our previous work demonstrated that the overexpression of HOXA5 in MCF7 cells resulted in cell death through a p53-dependent apoptotic pathway. To determine whether p53-independent apoptotic pathways are involved in HOXA5-induced cell death, we engineered a p53-mutant breast cancer cell line, Hs578T, to inducibly express HOXA5. Induction of HOXA5 expression led to cell death with features typical of apoptosis within 24 h, and the expression levels of mutant p53 and its target genes either decreased or remained unchanged. To decipher apoptotic pathways, the HOXA5-expressing cells were treated with a variety of apoptotic inhibitors. Besides a general caspase inhibitor, caspase 2- and 8-specific inhibitors largely abolished HOXA5-induced apoptosis, whereas caspase 1-, 3-, 6-, and 9-specific inhibitors had no significant effects. Western blot analysis further confirmed that caspases 2 and 8 were activated after the induction of HOXA5 expression. Further, several small interfering RNAs which specifically silenced caspase 2 and caspase 8 expression significantly blocked HOXA5-induced apoptosis. HOXA5 expression could also sensitize cells to tumor necrosis factor alpha-induced apoptosis by at least 100-fold. These results indicate that expression of HOXA5 can induce apoptosis through an apoptotic mechanism mediated by caspases 2 and 8.

scholarly journals Reovirus-Induced Apoptosis Is Mediated by TRAIL

2000 ◽  
Vol 74 (17) ◽  
pp. 8135-8139 ◽  
Author(s):  
Penny Clarke ◽  
Suzanne M. Meintzer ◽  
Spencer Gibson ◽  
Christian Widmann ◽  
Timothy P. Garrington ◽  
...  
Keyword(s):  
Death Receptor ◽  
Tnf Receptor ◽  
Death Domain ◽  
Apoptotic Pathway ◽  
Cellular Receptors ◽  
Trail Receptors ◽  
Infected Cells ◽  
Soluble Trail ◽  
Induced Apoptosis ◽  
Necrosis Factor

ABSTRACT Members of the tumor necrosis factor (TNF) receptor superfamily and their activating ligands transmit apoptotic signals in a variety of systems. We now show that the binding of TNF-related, apoptosis-inducing ligand (TRAIL) to its cellular receptors DR5 (TRAILR2) and DR4 (TRAILR1) mediates reovirus-induced apoptosis. Anti-TRAIL antibody and soluble TRAIL receptors block reovirus-induced apoptosis by preventing TRAIL-receptor binding. In addition, reovirus induces both TRAIL release and an increase in the expression of DR5 and DR4 in infected cells. Reovirus-induced apoptosis is also blocked following inhibition of the death receptor-associated, apoptosis-inducing molecules FADD (for FAS-associated death domain) and caspase 8. We propose that reovirus infection promotes apoptosis via the expression of DR5 and the release of TRAIL from infected cells. Virus-induced regulation of the TRAIL apoptotic pathway defines a novel mechanism for virus-induced apoptosis.

GSH extrusion and the mitochondrial pathway of apoptotic signalling

2000 ◽  
Vol 28 (2) ◽  
pp. 56-61 ◽  
Author(s):  
S. Coppola ◽  
L. Ghibelli
Keyword(s):  
Protein Interactions ◽  
Mitochondrial Pathway ◽  
Protein Protein Interactions ◽  
Cytochrome C Release ◽  
Apoptotic Pathway ◽  
Redox Imbalance ◽  
Mitochondrial Alterations ◽  
Execution Phase ◽  
Induced Apoptosis ◽  
Necessary And Sufficient

New evidence suggests that physiological and damaging agents activate two different pathways of apoptotic signalling, which are mediated by protein-protein interactions and mitochondrial alterations respectively. The two pathways converge at the activation of caspase 3, the key effector of the execution phase of apoptosis, thus giving similar final results. The knowledge that different biochemical routes exist allows us to re-evaluate previous apparently contradictory results concerning the events occurring during apoptosis, and their respective roles. In particular, this applies to the role of oxidative stress and redox imbalance in the signal transduction events of apoptosis. It now appears that oxidative alterations are absent, or at least unnecessary, for the development of the physiological pathway. Instead, clear indications are emerging showing that redox imbalance is required for the damage-induced mitochondrial pathway. This is suggested by the finding that the depletion of glutathione, a common event in damage-induced apoptosis, is necessary and sufficient to induce cytochrome c release, the key event of this pathway. A model is proposed with GSH efflux as the backbone of the damage-induced apoptotic pathway.

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