Related Experiment Video
Updated: May 28, 2026
07:17
Measuring Composition of CD95 Death-Inducing Signaling Complex and Processing of Procaspase-8 in this Complex
Published on: August 2, 2021
Caspase-8 activity has an essential role in CD95/Fas-mediated MAPK activation
A M M Kober1, S Legewie, C Pforr
1Division of Immunogenetics, German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany.
Cell Death & Disease
|October 7, 2011
Summary
CD95 stimulation triggers both cell death and survival pathways. Caspase-8 activation is key for MAPK signaling, with c-FLIP proteins regulating this process via the CD95 death-inducing signaling complex (DISC).
Area of Science:
- Cell Biology
- Molecular Signaling
- Systems Biology
Background:
- CD95 (Fas/APO-1) receptor stimulation initiates complex signaling cascades.
- Both apoptotic (cell death) and non-apoptotic (survival) pathways are induced, but their regulation is not fully understood.
- Mitogen-activated protein kinases (MAPKs), like ERK1/2 and p38, are involved in these non-apoptotic responses.
Purpose of the Study:
- To investigate the dynamics of DISC components, specifically DED proteins, procaspase-8, and c-FLIPs.
- To elucidate the role of these components in CD95-mediated activation of ERK1/2 and p38 MAPKs.
- To develop a mathematical model for CD95 DISC-mediated MAPK activation and apoptosis.
Main Methods:
- Quantitative immunoblots to measure protein levels and activation.
- Imaging techniques to visualize protein dynamics.
- Mathematical modeling to simulate and analyze signaling pathway kinetics.
Main Results:
- CD95 DISC-induced caspase-8 activity is crucial for initiating ERK1/2 and p38 MAPK activation.
- Both long (c-FLIP(L)) and short (c-FLIP(R)) isoforms of c-FLIP inhibit MAPK induction by preventing caspase-8 processing at the DISC.
- A mathematical model quantitatively described the dynamics leading to caspase-8 activation and subsequent MAPK/apoptotic pathway induction.
Conclusions:
- Caspase-8 plays a critical role in CD95-mediated MAPK activation.
- c-FLIP proteins act as key regulators, modulating caspase-8 processing and downstream signaling.
- Integrated biochemical and mathematical approaches provide insights into the complex regulation of CD95 signaling.
Related Concept Videos
01:24Caspases
Caspase, a family of cysteine proteases, serve as effectors in apoptosis. The ced3 gene in C.elegans was first identified to be involved in apoptosis. This gene encodes the ced-3 caspase that is similar to the interleukin-1-beta converting enzyme or ICE in mammals. In addition to apoptosis, caspases also function in the inflammatory response. Inflammatory caspases are essential in activating pro-inflammatory cytokines that recruit immune cells and block the replication of pathogens inside cells.
01:17The Extrinsic Apoptotic Pathway
The extrinsic apoptotic pathway is initiated when extracellular death-inducing signals, such as specific cytokines, activate the death receptors expressed on the cell surface. The immune cells involved in this pathway are natural killer cells (NK cells) and cytotoxic T-lymphocytes. NK cells are critical in innate immune response, while cytotoxic T-lymphocytes are associated with adaptive immune response. These cells recognize specific receptors expressed on the altered cells and activate...
01:07MAPK Signaling Cascades
Mitogen-activated protein kinase, or MAPK pathway, activates three sequential kinases to regulate cellular responses such as proliferation, differentiation, survival, and apoptosis. The canonical MAPK pathway starts with a mitogen or growth factor binding to an RTK. The activated RTKs stimulate Ras, which recruits Raf or MAP3 Kinase (MAPKKK), the first kinase of the MAPK signaling cascade. Raf further phosphorylates and activates MEK or MAP2 Kinases (MAPKK), which in turn phosphorylates MAP...
01:31The Intrinsic Apoptotic Pathway
Internal cellular stress, such as cellular injury or hypoxia, triggers intrinsic apoptosis. The B-cell lymphoma 2 (Bcl-2) family of proteins are the primary regulators of the intrinsic apoptotic pathway. For example, during DNA damage, checkpoint proteins, such as Ataxia Telangiectasia Mutated (ATM protein) and Checkpoints Factor-2 (Chk2) proteins, are activated. These proteins phosphorylate p53 which further activates pro-apoptotic proteins, such as Bax, Bak, PUMA, and Noxa, and inhibits...
01:25cAMP-dependent Protein Kinase Pathways
Cyclic Adenosine Monophosphate (cAMP) is an essential second messenger that activates protein kinase A (PKA) and regulates various biological processes. A single epinephrine molecule binds to GPCR and activates several heterotrimeric G proteins, each stimulating multiple adenylyl cyclase, amplifying the signal, and synthesizing large numbers of cAMP molecules. Small changes in cAMP concentration affect PKA activity. The binding of four cAMP molecules induces a conformational change in PKA,...
01:19Interactions Between Signaling Pathways
Signaling cascades usually lack linearity. Multiple pathways interact and regulate one another, allowing cells to integrate and respond to diverse environmental stimuli.
Convergence and divergence, and cross-talk between signaling pathways
Two distinct signaling pathways can converge on a single functional unit, which may either be a single protein or a complex of proteins. The response is either functionally distinct or synergistic between the two pathways but different from the response...
Convergence and divergence, and cross-talk between signaling pathways
Two distinct signaling pathways can converge on a single functional unit, which may either be a single protein or a complex of proteins. The response is either functionally distinct or synergistic between the two pathways but different from the response...