scholarly journals The Vaccinia Virus F1L Protein Interacts with the Proapoptotic Protein Bak and Inhibits Bak Activation

2005 ◽  
Vol 79 (22) ◽  
pp. 14031-14043 ◽  
Author(s):  
Shawn T. Wasilenko ◽  
Logan Banadyga ◽  
David Bond ◽  
Michele Barry
Keyword(s):  
Vaccinia Virus ◽  
Jurkat Cells ◽  
Wild Type ◽  
Inner Mitochondrial Membrane ◽  
Embryonic Fibroblasts ◽  
Cellular Immune Responses ◽  
Proapoptotic Protein ◽  
Cellular Apoptosis ◽  
Induced Apoptosis ◽  
Cellular Immune

ABSTRACT Many viruses have evolved strategies to counteract cellular immune responses, including apoptosis. Vaccinia virus, a member of the poxvirus family, encodes an antiapoptotic protein, F1L. F1L localizes to mitochondria and inhibits apoptosis by preventing the release of cytochrome c by an undetermined mechanism (S. T. Wasilenko, T. L. Stewart, A. F. Meyers, and M. Barry, Proc. Natl. Acad. Sci. USA 100:14345-14350, 2003; T. L. Stewart, S. T. Wasilenko, and M. Barry, J. Virol. 79:1084-1098, 2005). Here, we show that in the absence of an apoptotic stimulus, F1L associates with Bak, a proapoptotic member of the Bcl-2 family that plays a pivotal role in the release of cytochrome c. Cells infected with vaccinia virus were resistant to Bak oligomerization and the initial N-terminal exposure of Bak following the induction of apoptosis with staurosporine. A mutant vaccinia virus missing F1L was no longer able to inhibit apoptosis or Bak activation. In addition, the expression of F1L was essential to inhibit tBid-induced cytochrome c release in both wild-type murine embryonic fibroblasts (MEFs) and Bax-deficient MEFs, indicating that F1L could inhibit apoptosis in the presence and absence of Bax. tBid-induced Bak oligomerization and N-terminal exposure of Bak in Bax-deficient MEFs were inhibited during virus infection, as assessed by cross-linking and limited trypsin proteolysis. Infection with the F1L deletion virus no longer provided protection from tBid-induced Bak activation and apoptosis. Additionally, infection of Jurkat cells with the F1L deletion virus resulted in cellular apoptosis, as measured by loss of the inner mitochondrial membrane potential, caspase 3 activation, and cytochrome c release, indicating that the presence of F1L was pivotal for inhibiting vaccinia virus-induced apoptosis. Our data indicate that F1L expression during infection inhibits apoptosis and interferes with the activation of Bak.

scholarly journals Caspase3-deficient cells require fibronectin for protection against autophagy-dependent death

2021 ◽  
Author(s):  
David B. Weir ◽  
Lawrence H. Boise
Keyword(s):  
Cell Death ◽  
Survival Advantage ◽  
Deficient Mouse ◽  
Wild Type ◽  
Mouse Embryonic Fibroblasts ◽  
Embryonic Fibroblasts ◽  
Serum Withdrawal ◽  
Presence And Absence ◽  
Induced Apoptosis

ABSTRACTCaspases are required for execution of apoptosis. However, in their absence, signals that typically induce apoptosis can still result in cell death. Our laboratory previously demonstrated that Casp3-deficient mouse embryonic fibroblasts (MEFs) have increased fibronectin (FN) secretion, and an adhesion-dependent survival advantage compared to wild type (WT) MEFs. Here, we show that FN is required for survival of Casp3-deficient MEFs following serum withdrawal. Furthermore, when FN is silenced, serum withdrawal-induced death is caspase-independent. However, procaspase-7 is cleaved, suggesting that MOMP is taking place. Indeed, in the absence of FN, cytochrome c release is increased following serum withdrawal in Casp3-deficient MEFs. Yet death does not correspond to cytochrome c release in Casp3-deficient MEFs. This is true both in the presence and absence of FN. Additionally, caspase-independent death is inhibited by Bcl-XL overexpression. These findings suggest that Bcl-XL is not inhibiting death through regulation of Bax/Bak insertion into the mitochondria, but through a different mechanism. One such possibility is autophagy and induction of autophagy is associated with caspase-independent death in Casp3-deficient cells. Importantly, when ATG5 is ablated in Casp3-deficient cells, autophagy is blocked and death is largely inhibited. Taken together, our data indicate that Casp3-deficient cells incapable of undergoing canonical serum withdrawal-induced apoptosis, are protected from autophagy-dependent death by FN-mediated adhesion.

scholarly journals A Soluble Version of Nipah Virus Glycoprotein G Delivered by Vaccinia Virus MVA Activates Specific CD8 and CD4 T Cells in Mice

Viruses ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 26 ◽  
Author(s):  
Georgia Kalodimou ◽  
Svenja Veit ◽  
Sylvia Jany ◽  
Ulrich Kalinke ◽  
Christopher C. Broder ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Immune Responses ◽  
Vaccinia Virus ◽  
G Protein ◽  
Nipah Virus ◽  
Cell Responses ◽  
Cellular Immune Responses ◽  
Glycoprotein G ◽  
Cellular Immune

Nipah virus (NiV) is an emerging zoonotic virus that is transmitted by bats to humans and to pigs, causing severe respiratory disease and often fatal encephalitis. Antibodies directed against the NiV-glycoprotein (G) protein are known to play a major role in clearing NiV infection and in providing vaccine-induced protective immunity. More recently, T cells have been also shown to be involved in recovery from NiV infection. So far, relatively little is known about the role of T cell responses and the antigenic targets of NiV-G that are recognized by CD8 T cells. In this study, NiV-G protein served as the target immunogen to activate NiV-specific cellular immune responses. Modified Vaccinia virus Ankara (MVA), a safety-tested strain of vaccinia virus for preclinical and clinical vaccine research, was used for the generation of MVA–NiV-G candidate vaccines expressing different versions of recombinant NiV-G. Overlapping peptides covering the entire NiV-G protein were used to identify major histocompatibility complex class I/II-restricted T cell responses in type I interferon receptor-deficient (IFNAR−/−) mice after vaccination with the MVA–NiV-G candidate vaccines. We have identified an H2-b-restricted nonamer peptide epitope with CD8 T cell antigenicity and a H2-b 15mer with CD4 T cell antigenicity in the NiV-G protein. The identification of this epitope and the availability of the MVA–NiV-G candidate vaccines will help to evaluate NiV-G-specific immune responses and the potential immune correlates of vaccine-mediated protection in the appropriate murine models of NiV-G infection. Of note, a soluble version of NiV-G was advantageous in activating NiV-G-specific cellular immune responses using these peptides.

scholarly journals Adenovectors encoding RSV-F protein induce durable and mucosal immunity in macaques after two intramuscular administrations

npj Vaccines ◽  
2019 ◽  
Vol 4 (1) ◽  
Author(s):  
N. C. Salisch ◽  
A. Izquierdo Gil ◽  
D. N. Czapska-Casey ◽  
L. Vorthoren ◽  
J. Serroyen ◽  
...  
Keyword(s):  
T Cells ◽  
Adenoviral Vectors ◽  
Wild Type ◽  
F Protein ◽  
Cell Responses ◽  
Cellular Immune Responses ◽  
Cynomolgus Macaques ◽  
Syncytial Virus ◽  
Multiple Strains ◽  
Cellular Immune

AbstractRespiratory Syncytial Virus (RSV) can cause severe respiratory disease, yet a licensed vaccine is not available. We determined the immunogenicity of two homologous and one heterologous intramuscular prime-boost vaccination regimens using replication-incompetent adenoviral vectors of human serotype 26 and 35 (Ad26 and Ad35), expressing a prototype antigen based on the wild-type fusion (F) protein of RSV strain A2 in adult, RSV-naive cynomolgus macaques. All regimens induced substantial, boostable antibody responses that recognized the F protein in pre- and postfusion conformation, neutralized multiple strains of RSV, and persisted for at least 80 weeks. Vaccination induced durable systemic RSV-F-specific T-cell responses characterized mainly by CD4+ T cells expressing Th1-type cytokines, as well as RSV-F-specific CD4+ and CD8+ T cells, IgG, and IgA in the respiratory tract. Intramuscular immunization with Ad26 and 35 vectors thus is a promising approach for the development of an optimized RSV vaccine expected to induce long-lasting humoral and cellular immune responses that distribute systemically and to mucosal sites.

scholarly journals Induction of Cellular Immune Responses to Simian Immunodeficiency Virus Gag by Two Recombinant Negative-Strand RNA Virus Vectors

2004 ◽  
Vol 78 (17) ◽  
pp. 9366-9375 ◽  
Author(s):  
Yurie Nakaya ◽  
Takaaki Nakaya ◽  
Man-Seong Park ◽  
Jerome Cros ◽  
Jiro Imanishi ◽  
...  
Keyword(s):  
Immune Responses ◽  
Vaccinia Virus ◽  
Simian Immunodeficiency Virus ◽  
Rna Virus ◽  
Influenza Viruses ◽  
Gag Protein ◽  
Virus Vectors ◽  
Cellular Immune Responses ◽  
Immunodeficiency Virus ◽  
Cellular Immune

ABSTRACT A recombinant Newcastle disease virus (rNDV) expressing simian immunodeficiency virus (SIV) Gag protein (rNDV/SIVgag) was generated. The rNDV/SIVgag virus induced Gag-specific cellular immune responses in mice, leading to a specific anti-Gag antiviral immunity. This was evidenced by the inhibition of growth of recombinant vaccinia virus expressing an identical Gag antigen (rVac/SIVgag) but not of wild-type vaccinia virus in rNDV/SIVgag-immunized mice. Among intravenous, intraperitoneal, or intranasal immunization routes, intranasal administration induced the strongest protective response against challenge with rVac/SIVgag. We further demonstrated that these immune responses were greatly enhanced after booster immunization with recombinant influenza viruses expressing immunogenic portions of SIV Gag. The magnitude of the protective immune response correlated with the levels of cellular immune responses to Gag, which were still evident 9 weeks after immunization. These results suggest that rNDV and influenza virus vectors are suitable candidate vaccines against AIDS as well as against other infectious diseases.

scholarly journals Comparison of Apoptosis in Wild-Type and Fas-Resistant Cells: Chemotherapy-Induced Apoptosis Is Not Dependent on Fas/Fas Ligand Interactions

Blood ◽  
1997 ◽  
Vol 90 (3) ◽  
pp. 935-943 ◽  
Author(s):  
Christine M. Eischen ◽  
Timothy J. Kottke ◽  
Luis M. Martins ◽  
Guriqbal S. Basi ◽  
Jay S. Tung ◽  
...  
Keyword(s):  
Cell Death ◽  
Fas Ligand ◽  
Apoptotic Cell ◽  
Chemotherapeutic Agents ◽  
Jurkat Cells ◽  
Wild Type ◽  
Γ Irradiation ◽  
Human T Cell ◽  
Apoptotic Pathways ◽  
Induced Apoptosis

Abstract The Fas/Fas ligand (FasL) pathway is widely involved in apoptotic cell death in lymphoid and nonlymphoid cells. It has recently been postulated that many chemotherapeutic agents also induce cell death by activating the Fas/FasL pathway. In the present study we compared apoptotic pathways induced by anti-Fas or chemotherapeutic agents in the Jurkat human T-cell leukemia line. Immunoblotting showed that treatment of wild-type Jurkat cells with anti-Fas or the topoisomerase II-directed agent etoposide resulted in proteolytic cleavage of precursors for the cysteine-dependent aspartate-directed proteases caspase-3 and caspase-7 and degradation of the caspase substrates poly(ADP-ribose) polymerase (PARP) and lamin B1 . Likewise, affinity labeling with N-(Nα-benzyloxycarbonylglutamyl-Nε-biotinyllysyl)aspartic acid [(2,6-dimethyl-benzoyl)oxy]methyl ketone [Z-EK (bio)D-amok] labeled the same five active caspase species after each treatment, suggesting that the same downstream apoptotic pathways have been activated by anti-Fas and etoposide. Treatment with ZB4, an antibody that inhibits Fas-mediated cell death, failed to block etoposide-induced apoptosis, raising the possibility that etoposide does not initiate apoptosis through Fas/FasL interactions. To further explore the relationship between Fas- and chemotherapy-induced apoptosis, Fas-resistant Jurkat cells were treated with various chemotherapeutic agents. Multiple independently derived Fas-resistant Jurkat lines underwent apoptosis that was indistinguishable from that of the Fas-sensitive parental cells after treatment with etoposide, doxorubicin, topotecan, cisplatin, methotrexate, staurosporine, or γ-irradiation. These results indicate that antineoplastic treatments induce apoptosis through a Fas-independent pathway even though Fas- and chemotherapy-induced pathways converge on common downstream apoptotic effector molecules.

NF-κB Protection against Apoptosis Induced by HEMA

2004 ◽  
Vol 83 (11) ◽  
pp. 837-842 ◽  
Author(s):  
G. Spagnuolo ◽  
C. Mauro ◽  
A. Leonardi ◽  
M. Santillo ◽  
R. Paternò ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Protective Role ◽  
Oxygen Species ◽  
Wild Type ◽  
Mouse Embryonic Fibroblasts ◽  
Embryonic Fibroblasts ◽  
Primary Fibroblasts ◽  
Underlying Mechanisms ◽  
Induced Apoptosis ◽  
Dose Dependent

The cytotoxicity of dental monomers has been widely investigated, but the underlying mechanisms have not been elucidated. We studied the molecular mechanisms involved in cell death induced by HEMA. In human primary fibroblasts, HEMA induced a dose-dependent apoptosis that was confirmed by the activation of caspases-8, -9, and -3. We found an increase of reactive oxygen species (ROS) and NF-κB activation after HEMA exposure. Blocking of ROS production by anti-oxidants had no direct influence on apoptosis caused by HEMA, but inhibition of NF-κB increased the fraction of apoptotic cells. Accordingly, mouse embryonic fibroblasts (MEF) from p65−/− mice were more susceptible to HEMA-induced apoptosis than were wild-type controls. Our results indicate that exposure to HEMA triggers apoptosis and that this mechanism is not directly dependent upon redox signaling. Nevertheless, ROS induction by HEMA activates NF-κB, which exerts a protective role in counteracting apoptosis.

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