Related Experiment Video
Updated: Jul 26, 2026
07:17
Measuring Composition of CD95 Death-Inducing Signaling Complex and Processing of Procaspase-8 in this Complex
Published on: August 2, 2021
Lymphocyte life and death: the caspase-8 connection
Jun Tang1, Holli Kawadler, Xiaolu Yang
1Abramson Family Cancer Research Institute and Department of Cancer Biology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA.
Cancer Biology & Therapy
|August 6, 2005
Summary
Caspase-8 is crucial for immune responses, not just apoptosis. This study shows its enzymatic activity is essential for activating NF-kappaB in lymphocytes, linking it to antigen receptor signaling.
Area of Science:
- Immunology
- Molecular Biology
- Cell Signaling
Background:
- Caspase-8 is primarily known for its role in apoptosis via death receptors.
- Emerging research suggests caspase-8 has non-apoptotic functions, particularly in immune responses.
- Caspase-8 is vital for lymphocyte proliferation following antigen stimulation.
Purpose of the Study:
- To investigate the role of caspase-8 in antigen receptor-induced NF-kappaB activation.
- To elucidate the mechanism by which caspase-8 influences immune signaling pathways.
- To determine if caspase-8's enzymatic activity is necessary for NF-kappaB activation.
Main Methods:
- Utilized molecular biology techniques to identify key protein interactions.
- Investigated the role of caspase-8 in the activation cascade of the IKK complex.
- Assessed the requirement of caspase-8's enzymatic activity for NF-kappaB signaling.
Main Results:
- Identified caspase-8 as a critical component in the activation of the IKK complex.
- Established a link between the upstream Bcl10-MALT1 complex and the IKK complex via caspase-8.
- Demonstrated that the enzymatic activity of caspase-8, not just its presence, is required for NF-kappaB activation.
Conclusions:
- Caspase-8 plays a significant role in immune cell signaling beyond apoptosis.
- The enzymatic function of caspase-8 is essential for linking antigen receptor stimulation to NF-kappaB activation.
- This finding provides new insights into the molecular mechanisms of immune responses and lymphocyte activation.
Related Concept Videos
01:30Overview of Cell Death
Cell death is an essential process where the body gets rid of old or damaged cells. Cell proliferation and death need to be balanced, as an imbalance between the two may lead to cancer or autoimmune diseases.
Cell death was observed in the early 19th century, but there was no experimental evidence to prove it. In 1842, Carl Vogt first discovered cell death in a metamorphic toad; however, it was not termed ‘cell death.’ Scientists discovered different cell death pathways only in the 20th century...
Cell death was observed in the early 19th century, but there was no experimental evidence to prove it. In 1842, Carl Vogt first discovered cell death in a metamorphic toad; however, it was not termed ‘cell death.’ Scientists discovered different cell death pathways only in the 20th century...
01:30Apoptosis
Apoptosis is a combination of two Greek words, 'apo' and 'ptosis,' meaning separation and falling off, respectively. Hippocrates used this word to describe gangrene, which was caused due to bandaging of fractured bones. Apoptosis was distinguished from necrosis in 1970 when John Kerr reported observations of morphological changes occurring during apoptosis. During one experiment, he observed that the disruption of blood supply to the liver tissue resulted in a size reduction of the tissue.
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...
01:31The 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...
01:22Cellular Injury V: Apoptosis and Autophagy
Cells respond to damage and stress through highly coordinated processes that decide whether they survive or undergo controlled self-destruction. Two major pathways involved in this regulation are apoptosis, a type of programmed cell death, and autophagy, a survival mechanism that helps cells adapt to adverse conditions.ApoptosisApoptosis removes aged or injured cells to maintain tissue balance. During this process, the cell shrinks, chromatin condenses and fragments, and membrane-bound...