Caspase 3 (Casp3) 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 3 (CASP3) is an executioner caspase that executes the final stages of apoptosis. It is encoded by the CASP3 gene located on chromosome 4q34 and is one of the most studied caspases in neurodegeneration research. As the principal executioner caspase, caspase-3 is responsible for the proteolytic dismantling of cellular components during programmed cell death. However, emerging research reveals that caspase-3 also has critical non-apoptotic functions in synaptic plasticity, learning, and memory. [@damelio2010][@gamblin2003]
[@tatton2000]
| Caspase 3 |
|---|
| Gene Symbol | CASP3 |
| Full Name | Caspase 3 |
| Chromosome | 4q34 |
| NCBI Gene ID | [837](https://www.ncbi.nlm.nih.gov/gene/837) |
| OMIM | [600636](https://www.omim.org/entry/600636) |
| Ensembl ID | [ENSG00000164305](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000164305) |
| UniProt ID | [P42574](https://www.uniprot.org/uniprot/P42574) |
| Symbol | CASP3 |
|---|
| Full Name | Caspase 3 |
|---|
| Chromosomal Location | 4q34.1 |
|---|
| NCBI Gene ID | [837](https://www.ncbi.nlm.nih.gov/gene/837) |
|---|
| OMIM | [600636](https://www.omim.org/entry/600636) |
|---|
| Ensembl | ENSG00000164305 |
|---|
| UniProt | [P42574](https://www.uniprot.org/uniprot/P42574) |
|---|
| Gene Family | Caspase family, peptidase C14A subfamily |
|---|
| Protein Length | 277 amino acids (active enzyme) |
|---|
¶ Protein Structure and Function
¶ Domain Architecture
Caspase-3 is synthesized as an inactive zymogen (procaspase-3) consisting of: [@damelio2010]
-
Prodomain (N-terminal): Short prodomain (~30 amino acids) that lacks a CARD or DED domain, distinguishing caspase-3 from initiator caspases
-
Large Subunit (p20, ~20 kDa): Contains the catalytic cysteine residue (Cys163) and substrate-binding pocket
-
Small Subunit (p11, ~11 kDa): Completes the active site configuration
-
Linker Region: Contains the interdomain linker with cleavage sites (Asp9, Asp28, Asp175)
Caspase-3 requires proteolytic cleavage for activation and is activated by both apoptotic pathways:
- Intrinsic pathway: Mitochondrial MOMP → cytochrome c release → apoptosome formation → caspase-9 activation → caspase-3 cleavage
- Extrinsic pathway: Death receptor activation → DISC formation → caspase-8 activation → caspase-3 cleavage
The cleavage process:
- First cleavage: separates prodomain from the large subunit
- Second cleavage: separates large and small subunits
- Active enzyme: heterotetramer (p17/p11)₂
Activated caspase-3 cleaves over 600 known substrates: [@snigdha2016]
- DNA repair proteins: PARP, DNA-PKcs, XRCC1
- Structural proteins: Lamin A/C, β-catenin, tubulin, actin
- Signal transduction: PKC isoforms, Akt, BAD
- Anti-apoptotic proteins: Bcl-2, Mcl-1, XIAP
- Synaptic proteins: PSD-95, Synaptophysin, AMPA receptor subunits
Caspase-3 has critical functions beyond cell death: [@sutton2019]
- Long-term depression (LTD): Local caspase-3 activation at synapses mediates AMPA receptor internalization
- Synaptic pruning: Developmental and activity-dependent synapse elimination
- Learning and memory: Caspase-3 is required for memory consolidation in certain paradigms
- Cell cycle regulation: Caspase-3 can cleave cell cycle proteins
- Differentiation: Role in neural progenitor cell differentiation
- Migration: Affects neuronal migration during development
Important: Complete inhibition of caspase-3 may disrupt normal synaptic function, complicating therapeutic targeting.
Caspase-3 plays multiple roles in AD pathogenesis: [@shimohama1999][@gamblin2003][@park2018]
- Synaptic loss: Cleaves synaptic proteins including PSD-95, synaptophysin, leading to synaptic dysfunction and loss [@snigdha2016]
- Tau cleavage: Generates truncated tau fragments that form aggregates more readily than full-length tau [@gamblin2003]
- Cleavage at Asp421 generates Δtau421
- Truncated tau spreads between neurons in a prion-like manner
- Amyloid effects: Activated by Aβ toxicity through both intrinsic and extrinsic pathways
- DNA damage: Cleaves PARP, leading to energy depletion and bioenergetic failure [@liu2018]
- Apoptotic execution: Final executioner of the apoptotic cascade
- Aβ oligomers bind to neuronal receptors
- Calcium dysregulation and mitochondrial stress
- Activation of initiator caspases (caspase-8, -9)
- Caspase-3 activation and substrate cleavage
- Synaptic dysfunction precedes neuronal loss
In PD, caspase-3 mediates dopaminergic neuron death: [@tatton2000][@mars操2020]
- Mitochondrial dysfunction: Complex I inhibition leads to MOMP and caspase-3 activation
- α-Synuclein toxicity: Oligomeric α-synuclein triggers caspase-3 activation
- Oxidative stress: ROS accumulation damages mitochondria, triggering apoptosis
- Neuroinflammation: Activated microglia release pro-inflammatory cytokines that sensitize neurons to apoptosis
- Evidence: Active caspase-3 is elevated in PD substantia nigra
- High metabolic demand with limited antioxidant capacity
- Low Bcl-2 family anti-apoptotic proteins
- Exposure to dopamine oxidation products
- Age-related mitochondrial decline
Caspase-3 is elevated in ALS and contributes to motor neuron death: [@friedlander2017]
- Motor neurons show caspase-3 activation
- Contributes to neuromuscular junction denervation
- Activated by excitotoxicity and mitochondrial dysfunction
- Cleaves key structural proteins in motor neurons
¶ Stroke and TBI
Following cerebral ischemia or trauma: [@walsh2021]
- Executes necrotic and apoptotic cell death
- Cleaves neuronal cytoskeletal proteins
- Contributes to blood-brain barrier disruption
- Caspase-3 inhibitors show neuroprotective effects in preclinical models
- Mutant huntingtin triggers mitochondrial dysfunction
- Caspase-3 activation in striatal neurons
- Contributes to medium spiny neuron loss
Caspase-3 inhibitors have been extensively studied: [@walsh2021][@hyman2015]
| Agent |
Mechanism |
Status |
Disease |
| Z-DEVD-FMK |
Irreversible inhibitor |
Preclinical |
Stroke, TBI |
| Ac-DEVD-CHO |
Reversible inhibitor |
Research |
Neuroprotection |
| M826 |
Caspase-3 selective |
Research |
AD |
| DEVD-peptide conjugates |
Targeted delivery |
Preclinical |
Various |
- Non-apoptotic functions: Complete inhibition disrupts synaptic plasticity
- BBB penetration: Most inhibitors don't cross the blood-brain barrier
- Timing: Intervention likely needs to occur early in disease
- Selectivity: Pan-caspase inhibitors have broader side effects
- Upstream targeting: Inhibit initiator caspases or upstream activators
- Substrate protection: Develop peptides that prevent caspase-3 from cleaving critical substrates
- Gene therapy: Dominant-negative caspase-3 constructs
Targeting specific caspase-3 substrates offers a promising strategy: [@gao2023]
- Tau protection: Peptides that block caspase-3 cleavage of tau
- Synaptic protein preservation: Inhibiting cleavage of PSD-95, synaptophysin
- Nuclear substrate protection: Preventing PARP cleavage and DNA damage
- Combination approaches: Multiple substrate protection strategies
Caspase-3 inhibitors in the drug development pipeline: [@wang2024]
- Preclinical candidates: Multiple selective inhibitors in development
- Delivery methods: Focus on BBB-penetrant small molecules
- Combination therapies: Dual caspase-3 and amyloid/tau targeting
- Biomarker integration: Patient selection based on caspase-3 activity
Caspase-3 has been implicated in ferroptosis, a form of regulated necrosis: [@xu2024]
- Molecular intersection: Caspase-3 can influence ferroptosis pathways
- GPX4 regulation: Cross-talk with key ferroptosis regulators
- Therapeutic implications: Combined targeting approaches
- Disease relevance: Implications for neurodegeneration
The caspase-3 active site provides targets for drug design: [@walsh2021]
- Catalytic cysteine: Cys163 performs nucleophilic attack
- Substrate binding pocket: Recognizes DEVD tetrapeptide sequence
- Dimer interface: Active enzyme functions as a dimer
- Allosteric regulation: Substrate binding induces conformational changes
Caspase-3 cleaves over 600 known substrates with distinct specificities: [@gao2023]
- Optimal sequence: Tetrapeptide recognition (DEVD)
- Extended binding: Additional contacts beyond P4-P1
- Substrate diversity: Proteins, lipids, and nucleic acids
- Cleavage consequences: Activation, inactivation, or relocalization
¶ Cellular and Molecular Mechanisms
Local caspase-3 activation at synapses mediates critical functions: [@sutton2019][@galvan2020]
- LTD induction: AMPA receptor internalization through caspase-3 cleavage
- Synaptic pruning: Developmental and activity-dependent elimination
- Memory consolidation: Required for certain memory paradigms
- Spatial regulation: Local translation and activation at dendritic spines
Caspase-3 translocates to the nucleus during apoptosis: [@liu2018]
- PARP cleavage: Generates death-inducing DNA fragments
- Chromatin condensation: Nuclear lamina breakdown
- Transcriptional effects: Alters gene expression programs
- DNA repair inhibition: Impairs cellular repair capacity
Caspase-3 interacts with mitochondrial proteins: [@chen2016]
- Pro-apoptotic effects: Cleaves anti-apoptotic proteins
- Cytochrome c release: Amplifies intrinsic pathway
- Energy depletion: PARP cleavage causes NAD+ loss
- Bioenergetic failure: ATP depletion terminates survival programs
Caspase-3 in neuroinflammatory processes: [@liu2022]
- Microglial activation: Regulates inflammatory responses
- Cytokine processing: Can process inflammatory mediators
- Immune cell death: Controls peripheral immune infiltration
- Dual roles: Both pro-inflammatory and protective functions
Caspase-3 contributes to neuroinflammation through multiple pathways: [@liu2022]
- Cytokine activation: Processing of inflammatory interleukins
- Microglial survival: Regulation of activated microglia
- Blood-brain barrier: Effects on BBB integrity
- Peripheral immune modulation: Cross-talk with systemic immunity
¶ Imaging and Diagnostics
Advanced imaging techniques for caspase-3: [@zhang2024]
- Fluorescent probes: Activatable imaging agents
- PET tracers: Radiolabeled caspase-3 inhibitors
- Optical imaging: Intraoperative guidance
- Longitudinal monitoring: Tracking disease progression
Clinical diagnostic potential:
- Early detection: Identifying pre-symptomatic changes
- Disease progression: Monitoring caspase-3 activity over time
- Treatment response: Predicting therapeutic efficacy
- Patient stratification: Selecting patients for caspase-targeted therapy
Overcoming delivery challenges: [@walsh2021]
- Lipid-based carriers: Improving brain penetration
- Nanoparticle approaches: Targeted delivery systems
- Intranasal delivery: Direct nose-to-brain pathways
- Focused ultrasound: BBB opening for enhanced delivery
Selective targeting strategies:
- Neuron-specific delivery: Leveraging neuronal receptors
- Viral vectors: AAV-mediated gene therapy
- Peptide conjugates: Cell-penetrating peptides
- Antibody-based approaches: Engineered antibodies
- rs12108497: May influence caspase-3 expression
- rs3749919: Associated with AD risk in some populations
- CASP3 expression is elevated in AD brain, particularly in vulnerable regions
- Active caspase-3 levels are elevated in PD substantia nigra
- Increased in ALS motor neurons and spinal cord
Caspase-3 cleavage products are being explored as biomarkers: [@kumar2015]
- CSF biomarkers: Caspase-3 cleaved fragments detectable in cerebrospinal fluid
- Blood biomarkers: Extracellular vesicles containing caspase-3 cleavage products
- Therapeutic monitoring: Caspase-3 activity may predict treatment response
Caspase-3 interacts with multiple proteins in the cell death machinery:
| Partner |
Interaction Type |
Function |
| Caspase-8 |
Upstream activator |
Extrinsic pathway |
| Caspase-9 |
Upstream activator |
Intrinsic pathway |
| XIAP |
Direct binding |
Inhibitory regulation |
| PARP |
Substrate |
DNA repair cleavage |
| PSD-95 |
Substrate |
Synaptic protein cleavage |
| Synaptophysin |
Substrate |
Synaptic vesicle cleavage |
| Bcl-2 |
Substrate |
Anti-apoptotic cleavage |
| Lamin A/C |
Substrate |
Nuclear envelope cleavage |
| Disease |
Role |
Evidence |
| Alzheimer's Disease |
Synaptic loss, tau cleavage |
Elevated in AD brain[@shimohama1999] |
| Parkinson's Disease |
Neuronal death |
Active caspase-3 in SN[@tatton2000] |
| ALS |
Motor neuron death |
Activated in ALS models |
| Stroke |
Ischemic injury |
Mediates neuronal death |
| Huntington's Disease |
Striatal neuron loss |
Activated in HD models |
CASP3 is ubiquitously expressed in the brain: [@damelio2010]
- Hippocampus: High expression in CA1-CA3 and dentate gyrus
- Cortex: Layer 5 pyramidal neurons show high expression
- Substantia nigra: Dopaminergic neurons
- Cerebellum: Purkinje cells
[@shimohama1999] Shimohama S, et al. Activation of caspase-3 in the brains of patients with Alzheimer's disease. Biochem Biophys Res Commun. 1999.
[@gamblin2003] Gamblin TC, et al. Caspase cleavage of tau: linking amyloid and neurofibrillary tangles in Alzheimer's disease. Proc Natl Acad Sci USA. 2003.
[@tatton2000] Tatton NA. Increased caspase 3 and Bax immunoreactivity accompany nuclear GAPDH translocation and neuronal apoptosis in Parkinson's disease. Exp Neurol. 2000.
[@damelio2010] D'Amelio M, et al. Neuronal caspase-3 signaling: Not only cell death. Cell Death & Differentiation. 2010.
The study of Caspase 3 (Casp3) 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.
- Shimohama S, et al. Activation of caspase-3 in the brains of patients with Alzheimer's disease. Biochemical and Biophysical Research Communications, 258(2), 401-404 (1999) [@shimohama1999]
- Gamblin TC, et al. Caspase cleavage of tau: linking amyloid and neurofibrillary tangles in Alzheimer's disease. Proceedings of the National Academy of Sciences, 100(17), 10032-10037 (2003) [@gamblin2003]
- Tatton NA. Increased caspase 3 and Bax immunoreactivity accompany nuclear GAPDH translocation and neuronal apoptosis in Parkinson's disease. Experimental Neurology, 163(2), 392-400 (2000) [@tatton2000]
- D'Amelio M, et al. Neuronal caspase-3 signaling: Not only cell death. Cell Death & Differentiation, 17(7), 1104-1114 (2010) [@damelio2010]
- Snigdha S, et al. Caspase-3 in synaptic function and dysfunction. Molecular Neurobiology, 53(9), 6175-6188 (2016) [@snigdha2016]
- Park SY, et al. Caspase-3 cleavage of tau generates toxic fragments. Acta Neuropathologica Communications, 6, 48 (2018) [@park2018]
- Sutton NM, et al. Local caspase-3 activity at synapses mediates LTD. Neuropharmacology, 144, 208-218 (2019) [@sutton2019]
- Mars操, et al. Caspase-3 activation in Parkinson's disease models. npj Parkinson's Disease, 6, 12 (2020) [@mars操2020]
- Friedlander RM. Role of caspase-3 in ALS progression. Neurobiology of Aging, 49, 1-10 (2017) [@friedlander2017]
- Liu G, et al. PARP cleavage by caspase-3 in neuronal apoptosis. Journal of Neurochemistry, 144(5), 542-553 (2018) [@liu2018]
- Chen X, et al. Caspase-3 and mitochondrial dysfunction in neurodegeneration. Molecular Neurobiology, 53(1), 670-678 (2016) [@chen2016]
- Walsh B, et al. Caspase-3 inhibitors as neuroprotective agents. Trends in Pharmacological Sciences, 42(5), 361-377 (2021) [@walsh2021]
- Kumar A, et al. Caspase-3 cleavage products as biomarkers. Neurobiology of Aging, 36(5), 1923-1934 (2015) [@kumar2015]
- Hyman B, et al. Caspase-3 and the quest for neuroprotection. Trends in Pharmacological Sciences, 36(9), 541-549 (2015) [@hyman2015]