Caspase 8 is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.
Caspase-8 is encoded by the CASP8 gene. It is a Caspase family, initiator caspases involved in caspase-8 mediates extrinsic apoptosis by death receptors (fas/cd95, trail-r1/2, tnfr1). it can also...
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| Caspase-8 |
|---|
| Protein Name | Caspase-8 |
| Gene | [CASP8](/genes/casp8) |
| UniProt ID | [Q14790](https://www.uniprot.org/uniprot/Q14790) |
| PDB ID(s) | 1K7J, 1K8A, 2C7E, 2C7F, 3K7E, 4JJU, 4PSV |
| Molecular Weight | 55.4 kDa |
| Subcellular Localization | Cytoplasm, Cell Membrane |
| Protein Family | Caspase family, initiator caspases |
Caspase-8 exists as two isoforms (Caspase-8a and Caspase-8b) that differ by 2 amino acids. It has a long prodomain with two death effector domains (DEDs).
Caspase-8 mediates extrinsic apoptosis by death receptors (Fas/CD95, TRAIL-R1/2, TNFR1). It can also initiate a caspase cascade independent of mitochondria (Type I cells) or cleave Bid to engage the intrinsic pathway (Type II cells). Caspase-8 also has non-apoptotic roles in cell proliferation and differentiation.
Death receptor signaling contributes to neuronal apoptosis in AD.
Caspase-8 is activated by DJ-1 loss and contributes to dopaminergic neuron death.
Extrinsic apoptotic pathway contributes to ischemic neuronal injury.
Death receptor-mediated caspase-8 activation contributes to secondary injury.
Caspase-8 inhibitors (IETD-FMK) have shown neuroprotective potential in preclinical models of stroke and TBI.
Protein information and structure. UniProt Database.
Caspase-8 is activated by the death receptor pathway through a well-characterized cascade:
- Ligand binding: FasL, TRAIL, or TNF-α binds to their respective death receptors (Fas/CD95, TRAIL-R1/R2, TNFR1)
- DISC formation: Death-inducing signaling complex (DISC) assembles at the receptor
- Pro-caspase-8 recruitment: Pro-caspase-8 binds to the DISC via FADD adapter protein
- Auto-activation: Pro-caspase-8 undergoes autocatalytic cleavage to form active caspase-8
- Downstream execution: Active caspase-8 cleaves downstream effector caspases (caspase-3, -6, -7)
Caspase-8 has important non-apoptotic roles:
- Cell proliferation: Required for NF-κB activation and cell survival signaling
- Differentiation: Essential for T-cell differentiation and macrophage function
- Migration: Regulates actin cytoskeleton dynamics and cell motility
- Inflammation: Processes pro-inflammatory cytokines
- NF-κB pathway: Caspase-8 can activate NF-κB, promoting cell survival
- ERK pathway: Involved in cell survival signaling
- JNK pathway: Stress-activated kinase signaling
- Aβ oligomers can activate death receptors (Fas, TNFR1)
- Caspase-8 activation contributes to synaptic loss
- Elevated caspase-8 levels in AD brain tissue
- Death receptor signaling amplifies neuroinflammation
- DJ-1 loss-of-function increases caspase-8 activation
- Dopaminergic neurons are particularly vulnerable to extrinsic apoptosis
- α-Synuclein can sensitize cells to death receptor signaling
- Mitochondrial dysfunction cross-talk with extrinsic pathway
¶ Stroke and Ischemia
- Oxygen-glucose deprivation activates death receptors
- TNF-α and FasL release during ischemia
- Caspase-8 contributes to penumbra expansion
- Dual inhibition of caspase-8 and caspase-9 provides neuroprotection
- Secondary injury involves death receptor activation
- Caspase-8 mediates inflammatory responses
- Inhibition reduces both apoptotic and necrotic cell death
- Mutant huntingtin can interact with death receptor components
- Caspase-8 activation in striatal neurons
- Cross-talk with mitochondrial apoptotic pathway
- Death receptor signaling in motor neuron degeneration
- Astrocyte-mediated caspase-8 activation
- Potential therapeutic target
| Compound |
Type |
Status |
Notes |
| Z-IETD-FMK |
Peptide inhibitor |
Research tool |
Selective for caspase-8 |
| A-385,358 |
Small molecule |
Preclinical |
Brain-penetrant |
| Emricasan |
Pan-caspase inhibitor |
Clinical trials |
Not specific to caspase-8 |
- Fas/FasL blocking antibodies: Tested in preclinical models
- TRAIL receptor decoys: Potential for neuroprotection
- TNF-α inhibitors: Used in neurodegenerative disease models
- Dominant-negative caspase-8 mutants
- RNAi targeting caspase-8 expression
- Viral vector delivery of protective genes
- CSF caspase-8: Elevated in AD, PD, and ALS
- Peripheral blood mononuclear cells: Caspase-8 activation state
- Therapeutic response marker: Inhibition efficacy monitoring
- Active caspase-8 fragments in patient samples
- Correlates with disease progression
- Potential for diagnostic and prognostic use
- Activity assays: Fluorometric substrates (IETD-AFC)
- Western blot: Pro-caspase-8 and cleaved forms
- Immunohistochemistry: Tissue localization
- Flow cytometry: Cell surface death receptor analysis
- Caspase-8 conditional knockout mice
- Transgenic overexpression models
- Humanized mouse models for drug testing
The study of Caspase 8 has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.
Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.