Blocked negative selection of developing T cells in mice expressing the baculovirus p35 caspase inhibitor

Izquierdo, Manuel; Grandien, Alf; Criado, Luis M.; Robles, María S.; Leonardo, Esther; Albar, Juan Pablo; Buitrago, Gonzalo González de; Martı́nez-A, Carlos

doi:10.1093/emboj/18.1.156

Cited by 65 publications

(51 citation statements)

References 54 publications

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“…SEB binds to Vβ3,7,8,17-TCR-bearing T cells, which in mice make up a large proportion (~30%) of T lymphocytes, 50 and induces T-cell activation and AICD. 51 EL-4 syngeneic cells are used as target cells in murine CTL assays, 52,53 but also induce reactivation and AICD of effector T lymphocytes. After several transient synaptic contacts, CMAC + EL-4 cells and T lymphoblasts both underwent apoptosis (plasma membrane blebbing; Supplementary Video 8).…”

Section: Resultsmentioning

confidence: 99%

Protein kinase D1/2 is involved in the maturation of multivesicular bodies and secretion of exosomes in T and B lymphocytes

et al. 2015

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Multivesicular bodies (MVBs) are endocytic compartments that enclose intraluminal vesicles (ILVs) formed by inward budding from the limiting membrane of endosomes. In T lymphocytes, these ILV contain Fas ligand (FasL) and are secreted as 'lethal exosomes' following activation-induced fusion of the MVB with the plasma membrane. Diacylglycerol (DAG) and diacylglycerol kinase α (DGKα) regulate MVB maturation and polarized traffic, as well as subsequent secretion of pro-apoptotic exosomes, but the molecular basis underlying these phenomena remains unclear. Here we identify protein kinase D (PKD) family members as DAG effectors involved in MVB genesis and secretion. We show that the inducible secretion of exosomes is enhanced when a constitutively active PKD1 mutant is expressed in T lymphocytes, whereas exosome secretion is impaired in PKD2-deficient mouse T lymphoblasts and in PKD1/3-null B cells. Analysis of PKD2-deficient T lymphoblasts showed the presence of large, immature MVB-like vesicles and demonstrated defects in cytotoxic activity and in activation-induced cell death. Using pharmacological and genetic tools, we show that DGKα regulates PKD1/2 subcellular localization and activation. Our studies demonstrate that PKD1/2 is a key regulator of MVB maturation and exosome secretion, and constitutes a mediator of the DGKα effect on MVB secretory traffic. Exosomes are nanovesicles that form as intraluminal vesicles (ILVs) inside multivesicular bodies (MVBs) and are then secreted by numerous cell types. 1 ILVs are generated by inward budding of late endosome limiting membrane in a precisely regulated maturation process. 2,3 Two main pathways are involved in MVB maturation. 4,5 In addition to the ESCRT (endosomal complex required for traffic) proteins, 6 there is increasing evidence that lipids such as lyso-bisphosphatidic acid (LBPA), 7 ceramides 8 and diacylglycerol (DAG) 9 contribute to this membrane invagination process.Exosomes participate in many biological processes related to T-cell receptor (TCR)-triggered immune responses, including T lymphocyte-mediated cytotoxicity and activationinduced cell death (AICD), antigen presentation and intercellular miRNA exchange. [10][11][12][13][14][15] The discovery of exosome involvement in these responses increased interest in the regulation of exosome biogenesis and secretory traffic, with special attention to the contribution of lipids such as ceramide and DAG, as well as DAG-binding proteins. 14,16-21 These studies suggest that positive and negative DAG regulators may control secretory traffic. By transforming DAG into phosphatidic acid (PA), diacylglycerol kinase α (DGKα) is essential for the negative control of DAG function in T lymphocytes. 22 DGKα translocates transiently to the T-cell membrane after human muscarinic type 1 receptor (HM1R) triggering or to the immune synapse (IS) after TCR stimulation; at these subcellular locations, DGKα acts as a negative modulator of phospholipase C (PLC)-generated DAG. 23,24 The secretory vesicle pathway involves several DAGc...

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Section: Resultsmentioning

confidence: 99%

Protein kinase D1/2 is involved in the maturation of multivesicular bodies and secretion of exosomes in T and B lymphocytes

et al. 2015

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“…Indeed, P49 blocked virus-induced apoptosis in cultured cells from Drosophila (Figure 8). Apoptosis of DL-1 cells was also suppressed by P35, which has been shown to prevent programmed cell death in invertebrates and vertebrates (Hay et al, 1994;Sugimoto et al, 1994;Grether et al, 1995;Izquierdo et al, 1999;Hisahara et al, 2000;Viswanath et al, 2000). Since P49 and P35 were proteolytically cleaved in Drosophila cells (Figure 8), a substrate inhibitor mechanism for both apoptotic suppressors is likely.…”

Section: P49 Blocks Virus-induced Apoptosis In Drosophilamentioning

confidence: 93%

Baculovirus apoptotic suppressor P49 is a substrate inhibitor of initiator caspases resistant to P35 in vivo

Zoog¹

2002

The EMBO Journal

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Caspases play a critical role in the execution of metazoan apoptosis and are thus attractive therapeutic targets for apoptosis-associated diseases. Here we report that baculovirus P49, a homolog of pancaspase inhibitor P35, prevents apoptosis in invertebrates by inhibiting an initiator caspase that is P35 insensitive. Consequently P49 blocked proteolytic activation of effector caspases at a unique step upstream from that affected by P35 but downstream from inhibitor of apoptosis Op-IAP. Like P35, P49 was cleaved by and stably associated with its caspase target. Ectopically expressed P49 blocked apoptosis in cultured cells from a phylogenetically distinct organism, Drosophila melanogaster. Furthermore, P49 inhibited human caspase-9, demonstrating its capacity to affect a vertebrate initiator caspase. Thus, P49 is a substrate inhibitor with a novel in vivo speci®city for a P35-insensitive initiator caspase that functions at an evolutionarily conserved step in the caspase cascade. These data indicate that activated initiator caspases provide another effective target for apoptotic intervention by substrate inhibitors.

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“…However, Apaf-1 -/-thymocytes have no defect in negative selection [157]. Pan-caspase inhibitor p35 T cell specific transgenic mice led to contradictory results in terms of negative selection [158,159]. In one study, the p35 transgene rescues specific peptide and superantigen induced thymocyte apoptosis in F5 TCR transgenic mice in vivo [158].…”

Section: Sp Thymocytes and Negative Selectionmentioning

confidence: 99%

“…Pan-caspase inhibitor p35 T cell specific transgenic mice led to contradictory results in terms of negative selection [158,159]. In one study, the p35 transgene rescues specific peptide and superantigen induced thymocyte apoptosis in F5 TCR transgenic mice in vivo [158]. p35 transgenic thymocytes are also resistant to anti-CD3 induced apoptosis in vitro [158].…”

Section: Sp Thymocytes and Negative Selectionmentioning

confidence: 99%

“…In one study, the p35 transgene rescues specific peptide and superantigen induced thymocyte apoptosis in F5 TCR transgenic mice in vivo [158]. p35 transgenic thymocytes are also resistant to anti-CD3 induced apoptosis in vitro [158]. However, in another study, the p35 transgene could only rescue 7-10% thymocytes from anti-CD3 induced apoptosis in vitro [159].…”

Section: Sp Thymocytes and Negative Selectionmentioning

confidence: 99%

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The role of apoptosis in the development and function of T lymphocytes

et al. 2005

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Apoptosis plays an essential role in T cell biology. Thymocytes expressing nonfunctional or autoreactive TCRs are eliminated by apoptosis during development. Apoptosis also leads to the deletion of expanded effector T cells during immune responses. The dysregulation of apoptosis in the immune system results in autoimmunity, tumorogenesis and immunodeficiency. Two major pathways lead to apoptosis: the intrinsic cell death pathway controlled by Bcl-2 family members and the extrinsic cell death pathway controlled by death receptor signaling. These two pathways work together to regulate T lymphocyte development and function.

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Blocked negative selection of developing T cells in mice expressing the baculovirus p35 caspase inhibitor

Cited by 65 publications

References 54 publications

Protein kinase D1/2 is involved in the maturation of multivesicular bodies and secretion of exosomes in T and B lymphocytes

Protein kinase D1/2 is involved in the maturation of multivesicular bodies and secretion of exosomes in T and B lymphocytes

Baculovirus apoptotic suppressor P49 is a substrate inhibitor of initiator caspases resistant to P35 in vivo

The role of apoptosis in the development and function of T lymphocytes

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