scholarly journals FLIPL induces caspase 8 activity in the absence of interdomain caspase 8 cleavage and alters substrate specificity

2011 ◽  
Vol 433 (3) ◽  
pp. 447-457 ◽  
Author(s):  
Cristina Pop ◽  
Andrew Oberst ◽  
Marcin Drag ◽  
Bram J. Van Raam ◽  
Stefan J. Riedl ◽  
...  
Keyword(s):  
Catalytic Domain ◽  
Functional Divergence ◽  
Caspase 8 ◽  
Death Domain ◽  
Extrinsic Pathway ◽  
Inhibitory Protein ◽  
Developmental Abnormalities ◽  
Developmental Role ◽  
Apoptotic Pathways

Caspase 8 is an initiator caspase that is activated by death receptors to initiate the extrinsic pathway of apoptosis. Caspase 8 activation involves dimerization and subsequent interdomain autoprocessing of caspase 8 zymogens, and recently published work has established that elimination of the autoprocessing site of caspase 8 abrogates its pro-apoptotic function while leaving its proliferative function intact. The observation that the developmental abnormalities of caspase 8-deficient mice are shared by mice lacking the dimerization adapter FADD (Fas-associated death domain) or the caspase paralogue FLIPL [FLICE (FADD-like interleukin 1β-converting enzyme)-inhibitory protein, long form] has led to the hypothesis that FADD-dependent formation of heterodimers between caspase 8 and FLIPL could mediate the developmental role of caspase 8. In the present study, using an inducible dimerization system we demonstrate that cleavage of the catalytic domain of caspase 8 is crucial for its activity in the context of activation by homodimerization. However, we find that use of FLIPL as a partner for caspase 8 in dimerization-induced activation rescues the requirement for intersubunit linker proteolysis in both protomers. Moreover, before processing, caspase 8 in complex with FLIPL does not generate a fully active enzyme, but an attenuated species able to process only selected natural substrates. Based on these results we propose a mechanism of caspase 8 activation by dimerization in the presence of FLIPL, as well as a mechanism of caspase 8 functional divergence in apoptotic and non-apoptotic pathways.

scholarly journals C5, A Cassaine Diterpenoid Amine, Induces Apoptosis via the Extrinsic Pathways in Human Lung Cancer Cells and Human Lymphoma Cells

2020 ◽  
Vol 21 (4) ◽  
pp. 1298 ◽  
Author(s):  
Hyo-Jin Kim ◽  
Bo-Gyeong Seo ◽  
Kwang Dong Kim ◽  
Jiyun Yoo ◽  
Joon-Hee Lee ◽  
...  
Keyword(s):  
Cancer Cells ◽  
Death Receptor ◽  
B Cell Lymphoma ◽  
Human Lung Cancer ◽  
Caspase 8 ◽  
Death Domain ◽  
Extrinsic Pathway ◽  
Inhibitory Protein ◽  
Apoptosis Pathways ◽  
Induced Apoptosis

Apoptosis pathways in cells are classified into two pathways: the extrinsic pathway, mediated by binding of the ligand to a death receptor and the intrinsic pathway, mediated by mitochondria. Apoptosis is regulated by various proteins such as Bcl-2 (B-cell lymphoma 2) family and cellular FLICE (Fas-associated Death Domain Protein Interleukin-1β-converting enzyme)-inhibitory protein (c-FLIP), which have been reported to inhibit caspase-8 activity. In this study, it was found that C5 (3β-Acetyl-nor-erythrophlamide), a compound of cassaine diterpene amine from Erythrophleum fordii, induced cell apoptosis in a variety of types of cancer cells. Induction of apoptosis in cancer cells by C5 was inversely related to the level of Bcl-2 expression. Overexpression of Bcl-2 into cancer cells significantly decreased C5-induced apoptosis. It was also found that treatment of cancer cells with a caspase-8 inhibitor significantly suppressed C5-induced apoptosis; however, treatment with caspase-9 inhibitors did not affect C5-induced apoptosis, suggesting that C5 may induce apoptosis via the extrinsic pathway by activating caspase-8. It was confirmed that treatment with C5 alone induced an association of FADD with procaspase-8; however, overexpression of c-FLIP decreased C5-induced caspase-8 activation. In conclusion, C5 could be utilized as a new useful lead compound for the development of an anti-cancer agent that has the goal of apoptosis.

scholarly journals The flip side of FLIP

2004 ◽  
Vol 382 (2) ◽  
Author(s):  
Marcus E. PETER
Keyword(s):  
Mammalian Cells ◽  
Caspase 8 ◽  
Death Domain ◽  
Extrinsic Pathway ◽  
Inhibitory Protein ◽  
Apoptosis Pathway ◽  
Surface Receptors ◽  
Biochemical Journal ◽  
Initiator Caspases ◽  
Extrinsic Apoptosis

Two major pathways regulate apoptosis induction in mammalian cells. In the extrinsic pathway, apoptosis is induced through specialized surface receptors, whereas in the intrinsic pathway, apoptosis is induced from within the cell, mainly through activation of mitochondria. Shortly after the major mediators of the extrinsic apoptosis pathway, the initiator caspases-8 and -10, were identified, c-FLIP [FLICE-like inhibitory protein; FLICE is FADD (Fas-associated death domain protein)-like interleukin-1β-converting enzyme], a catalytically inactive caspase-8/-10 homologue, was reported. Whether this structure acts as an inhibitor or promoter of the extrinsic apoptosis pathway has been the subject of much debate. In this issue of the Biochemical Journal, Boatright et al. provide further evidence for the long splice form of c-FLIP (c-FLIPL) being an activator of caspase-8/-10, and demonstrate that the resulting heterodimer is enzymically active with a substrate specificity identical with that of the caspase-8 homodimer. Our understanding of the regulators of the extrinsic apoptosis signalling pathway biochemically may provide the means to design drugs to correct the imbalance between apoptosis and proliferation, as found in many diseases.

Maturation of dendritic cells leads to up-regulation of cellular FLICE-inhibitory protein and concomitant down-regulation of death ligand–mediated apoptosis

Blood ◽  
2000 ◽  
Vol 96 (7) ◽  
pp. 2628-2631 ◽  
Author(s):  
Martin Leverkus ◽  
Henning Walczak ◽  
Alex McLellan ◽  
Hans-Werner Fries ◽  
Gabi Terbeck ◽  
...  
Keyword(s):  
Dendritic Cells ◽  
Tumor Necrosis ◽  
Caspase 8 ◽  
Inhibitory Protein ◽  
Cd95 Ligand ◽  
Induction Of Apoptosis ◽  
Low Levels ◽  
Necrosis Factor ◽  
Dc Maturation

Dendritic cells (DCs) disappear from lymph nodes 1 to 2 days after antigen presentation, presumably by apoptosis. To evaluate the role of death ligands in elimination of DCs, we analyzed the sensitivity of human DCs to CD95 ligand (CD95L) and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). We found mature DCs to be resistant to killing via CD95L or TRAIL, whereas only immature DCs were partially sensitive. However, all DC populations expressed CD95, TRAIL-R2, and TRAIL-R3 at comparable levels, suggesting that sensitivity to death ligand-induced DC apoptosis is not regulated at the receptor level. Interestingly, mature DCs highly expressed the caspase 8 inhibitory protein cFLIP, whereas only low levels were detected in immature DCs. Thus, death ligand sensitivity proved to be dependent on DC maturation and inversely correlated with expression levels of cFLIP. Induction of apoptosis by TRAIL or CD95L does not seem to play a role in the elimination of mature DCs, but instead might serve to regulate immature DC populations.

scholarly journals The role of Ubiquitination in Apoptosis and Necroptosis

2021 ◽  
Author(s):  
Jamie Z. Roberts ◽  
Nyree Crawford ◽  
Daniel B. Longley
Keyword(s):  
Cell Death ◽  
Death Receptors ◽  
Tnf Receptor ◽  
Extrinsic Pathway ◽  
Post Translational Modifications ◽  
Cell Death Pathways ◽  
Apoptotic Pathways ◽  
Extrinsic Apoptotic Pathways ◽  
Necrosis Factor

AbstractCell death pathways have evolved to maintain tissue homoeostasis and eliminate potentially harmful cells from within an organism, such as cells with damaged DNA that could lead to cancer. Apoptosis, known to eliminate cells in a predominantly non-inflammatory manner, is controlled by two main branches, the intrinsic and extrinsic apoptotic pathways. While the intrinsic pathway is regulated by the Bcl-2 family members, the extrinsic pathway is controlled by the Death receptors, members of the tumour necrosis factor (TNF) receptor superfamily. Death receptors can also activate a pro-inflammatory type of cell death, necroptosis, when Caspase-8 is inhibited. Apoptotic pathways are known to be tightly regulated by post-translational modifications, especially by ubiquitination. This review discusses research on ubiquitination-mediated regulation of apoptotic signalling. Additionally, the emerging importance of ubiquitination in regulating necroptosis is discussed.

scholarly journals Role of Insulin Receptor and Balance in Insulin Receptor Isoforms A and B in Regulation of Apoptosis in Simian Virus 40-immortalized Neonatal Hepatocytes

2008 ◽  
Vol 19 (3) ◽  
pp. 1185-1198 ◽  
Author(s):  
Carmen Nevado ◽  
Manuel Benito ◽  
Angela M. Valverde
Keyword(s):  
Insulin Receptor ◽  
Caspase 3 ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
Caspase 8 ◽  
Death Domain ◽  
Cytochrome C Release ◽  
Insulin Receptor Isoforms ◽  
Neonatal Hepatocytes

We have investigated the unique role of the insulin receptor (IR) and the balance of its isoforms A and B in the regulation of apoptosis in simian virus 40 (SV40)-immortalized neonatal hepatocytes. Immortalized hepatocytes lacking (HIR KO) or expressing the entire IR (HIR LoxP), and cells expressing either IRA (HIR RecA) or IRB (HIR RecB) have been generated. IR deficiency in hepatocytes increases sensitivity to the withdrawal of growth factors, because these cells display an increase in reactive oxygen species, a decrease in Bcl-xL, a rapid accumulation of nuclear Foxo1, and up-regulation of Bim. These events resulted in acceleration of caspase-3 activation, DNA laddering, and cell death. The single expression of either IRA or IRB produced a stronger apoptotic phenotype. In these cells, protein complexes containing IRA or IRB and Fas/Fas-associating protein with death domain activated caspase-8, and, ultimately, caspase-3. In hepatocytes expressing IRA, Bid cleavage and cytochrome C release were increased whereas direct activation of caspase-3 by caspase-8 and a more rapid apoptotic process occurred in hepatocytes expressing IRB. Conversely, coexpression of IRA and IRB in IR-deficient hepatocytes rescued from apoptosis. Our results suggest that balance alteration of IRA and IRB may serve as a ligand-independent apoptotic trigger in hepatocytes, which may regulate liver development.

scholarly journals TNF-α-mediated cardiorenal injury after rhabdomyolysis in rats

2015 ◽  
Vol 308 (11) ◽  
pp. F1259-F1267 ◽  
Author(s):  
Eduardo Homsi ◽  
Diego Duarte Andreazzi ◽  
Jose Butori Lopes de Faria ◽  
Patrícia Janino
Keyword(s):  
Cellular Response ◽  
Caspase 8 ◽  
Infliximab Treatment ◽  
Death Domain ◽  
Caspase 9 ◽  
Inhibitory Protein ◽  
Similar Reduction ◽  
Tubular Necrosis ◽  
Glycerol Injection ◽  
Tnf Α

The TNF-α serum level increases after rhabdomyolysis and is involved in the subsequent cardiorenal injury. In the present study, we investigated the TNF-α-dependent cell signaling pathways implicated in cellular injury in these organs. Rhabdomyolysis was induced by intramuscular glycerol injection in rats. Renal function, cardiac and renal pathology, and activation of caspases were evaluated during the first 24 h after glycerol injection. TNF-α blockade with infliximab reduced tubular necrosis and cardiorenal apoptosis. Cellular Fas-associated protein with death domain-like IL-1β-converting enzyme inhibitory protein (cFLIP), an inhibitor of caspase-8, was overexpressed in the kidney but not in the heart. The inhibitory effect of cFLIP blunted caspase-8 activation in the kidney. In this condition, the cellular response to the TNF-α stimulus was driven to receptor-interacting protein-1 (RIP1)-mediated necroptosis. Treatment with RIP1 inhibitor (necrostatin-1) isolated or in combination with infliximab showed a similar reduction in tubular necrosis, underscoring the importance of TNF-α-mediated tubular necroptosis in this model. TNF-α played a positive regulatory role in the transcription of proapoptotic Bax and p53-upregulated modulator of apoptosis (PUMA) proteins. Infliximab treatment reduced caspase-9-mediated apoptosis in both organs. Treatment with a caspase-8 inhibitor showed that caspase-8 participated in the process of apoptosis only in the heart, upstream of caspase-9 activation. TNF-α-mediated necroptosis is the predominant form of tubular injury observed in the glycerol model. TNF-α up regulates Bax and PUMA proapoptotic proteins, resulting in activation of the intrinsic pathway of apoptosis in the kidney and heart.

scholarly journals Cellular FLICE-inhibitory protein is required for T cell survival and cycling

2005 ◽  
Vol 202 (3) ◽  
pp. 405-413 ◽  
Author(s):  
Hien Chau ◽  
Veronica Wong ◽  
Nien-Jung Chen ◽  
Huey-Lan Huang ◽  
Wen-Jye Lin ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cell Survival ◽  
Cell Function ◽  
Embryonic Stem ◽  
Underlying Mechanism ◽  
Caspase 8 ◽  
Death Domain ◽  
Inhibitory Protein ◽  
T Cell Survival

Fas-associated death domain (FADD) and caspase-8 are key signal transducers for death receptor–induced apoptosis, whereas cellular FLICE-inhibitory protein (cFLIP) antagonizes this process. Interestingly, FADD and caspase-8 also play a role in T cell development and T cell receptor (TCR)–mediated proliferative responses. To investigate the underlying mechanism, we generated cFLIP-deficient T cells by reconstituting Rag−/− blastocysts with cFLIP-deficient embryonic stem cells. These Rag chimeric mutant mice (rcFLIP−/−) had severely reduced numbers of T cells in the thymus, lymph nodes, and spleen, although mature T lymphocytes did develop. Similar to FADD- or caspase-8–deficient cells, rcFLIP−/− T cells were impaired in proliferation in response to TCR stimulation. Further investigation revealed that cFLIP is required for T cell survival, as well as T cell cycling in response to TCR stimulation. Interestingly, some signaling pathways from the TCR complex appeared competent, as CD3 plus CD28 cross-linking was capable of activating the ERK pathway in rcFLIP−/− T cells. We demonstrate an essential role for cFLIP in T cell function.

scholarly journals Caspase-8 prevents sustained activation of NF-κB in monocytes undergoing macrophagic differentiation

Blood ◽  
2006 ◽  
Vol 109 (4) ◽  
pp. 1442-1450 ◽  
Author(s):  
Cédric Rébé ◽  
Séverine Cathelin ◽  
Sophie Launay ◽  
Rodolphe Filomenko ◽  
Laurent Prévotat ◽  
...  
Keyword(s):  
Death Receptor ◽  
Adaptor Protein ◽  
Cell Types ◽  
Caspase 8 ◽  
Specific Cell ◽  
Death Domain ◽  
Blood Monocytes ◽  
Inhibitory Protein ◽  
Interacting Protein ◽  
Macrophage Colony

Abstract Caspases have demonstrated several nonapoptotic functions including a role in the differentiation of specific cell types. Here, we show that caspase-8 is the upstream enzyme in the proteolytic caspase cascade whose activation is required for the differentiation of peripheral-blood monocytes into macrophages. On macrophage colony-stimulating factor (M-CSF) exposure, caspase-8 associates with the adaptor protein Fas-associated death domain (FADD), the serine/threonine kinase receptor-interacting protein 1 (RIP1) and the long isoform of FLICE-inhibitory protein FLIP. Overexpression of FADD accelerates the differentiation process that does not involve any death receptor. Active caspase-8 cleaves RIP1, which prevents sustained NF-κB activation, and activates downstream caspases. Together these data identify a role for caspase-8 in monocytes undergoing macrophagic differentiation, that is, the enzyme activated in an atypical complex down-regulates NF-κB activity through RIP1 cleavage.

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