Protein kinases represent one of the most promising therapeutic target classes for neurodegenerative diseases. Kinases regulate critical cellular processes including endolysosomal trafficking, neuroinflammation, mitochondrial homeostasis, and protein quality control systems—all of which are frequently dysregulated in Alzheimer's disease, Parkinson's disease, and multiple sclerosis.
This mechanism page synthesizes the current state of kinase-targeted drug development for neurodegenerative disorders, based on the comprehensive review by Shomali and Trempe in Pharmacology Reviews (2026) PMID:41880688].
CDK5 is a proline-directed serine/threonine kinase activated by binding partners p35 or p39. It plays a critical role in neuronal development and synaptic function, but dysregulated CDK5 activity contributes to tau hyperphosphorylation and neurofibrillary tangle formation in Alzheimer's disease.
Role in Disease:
- Phosphorylates tau at multiple sites associated with NFT formation
- Regulates amyloid precursor protein (APP) processing
- Controls synaptic vesicle trafficking
- Contributes to neuronal death through p53 activation
Therapeutic Approaches:
- Inhibitors: Roscovitine, Flavopiridol (pan-CDK inhibitors with limited brain penetration)
- Allosteric inhibitors targeting CDK5-p35 interaction
- Prodrugs designed to cross the blood-brain barrier
Preclinical Evidence:
- CDK5 knockdown reduces tau pathology in 3xTG-AD mice
- p25 transgenic mice show CDK5 hyperactivation with enhanced tau pathology
- Neuroprotective effects in multiple animal models
See the CDK5 gene page for more details on this target.
GSK3 exists as two isoforms: GSK3α and GSK3β. It is a multifunctional serine/threonine kinase involved in numerous cellular processes including glycogen metabolism, gene transcription, and apoptosis. GSK3β is particularly implicated in Alzheimer's disease pathogenesis.
Role in Disease:
- Phosphorylates tau at multiple pathogenic sites (Ser396, Ser404, Thr181)
- Regulates amyloid-β production through APP processing
- Promotes inflammatory responses via NF-κB activation
- Contributes to synaptic dysfunction
Therapeutic Approaches:
- ATP-competitive inhibitors: Tideglusib, SB-216763
- Isoform-selective inhibitors under development
- Lithium (indirect GSK3 inhibition via upstream mechanisms)
Clinical Trials:
- Tideglusib (NP-12): Completed Phase II trials in AD with mixed results
- Lithium: Ongoing trials for AD and ALS
See GSK3B gene page and GSK3 mechanism page for more details.
LRRK2 is a large ROCO kinase with GTPase and kinase domains. Gain-of-function mutations are the most common genetic cause of familial Parkinson's disease (G2019S, R1441C/H/G).
Role in Disease:
- Regulates endolysosomal trafficking and autophagy
- Controls mitochondrial dynamics and quality control
- Modulates inflammatory responses in microglia
- Affects synaptic function and dopamine neuron survival
Therapeutic Approaches:
- ATP-competitive inhibitors: DNL151 (Denali), GLC-474 (Genentech)
- Brain-penetrant compounds in clinical development
- Allosteric inhibitors targeting the kinase domain
Clinical Trials:
- DNL151: Completed Phase I, showed target engagement
- BIIB122 (DNL151): Phase II trials in PD (LBP-PD)
- GLC-474: Preclinical/Phase I
See LRRK2 gene page and LRRK2 pathway page for more details.
PINK1 is a serine/threonine-protein kinase that acts as a master regulator of mitophagy. Loss-of-function mutations cause early-onset familial Parkinson's disease.
Role in Disease:
- Recruits Parkin to damaged mitochondria
- Phosphorylates ubiquitin and Parkin to activate mitophagy
- Protects against oxidative stress
- Maintains mitochondrial integrity
Therapeutic Approaches:
- Activators of PINK1-Parkin pathway
- Small molecules stabilizing PINK1 on mitochondrial outer membrane
- Gene therapy approaches
Preclinical Evidence:
- PINK1 knockin mice show mitochondrial dysfunction
- Adenoviral PINK1 delivery protects against MPTP toxicity
- Phosphomimetic Parkin shows enhanced mitophagy
See PINK1 gene page for more details.
The p38 MAPK family (α, β, γ, δ isoforms) mediates cellular stress responses and inflammatory signaling. p38α is the most studied in neurodegeneration.
Role in Disease:
- Mediates cytokine production in microglia (IL-1β, TNF-α)
- Promotes neuronal apoptosis under stress conditions
- Contributes to blood-brain barrier dysfunction
- Regulates tau pathology through kinase activation
Therapeutic Approaches:
- p38α inhibitors: Losmapimod, Pamapimod
- Brain-penetrant compounds under development
- Anti-inflammatory strategies
Clinical Trials:
- Losmapimod: Tested in AD and ALS (Phase II)
- Mixed results due to limited efficacy and safety concerns
See MAPK14 gene page and p38 MAPK pathway page for more details.
BTK is a non-receptor tyrosine kinase involved in B-cell receptor signaling and myeloid cell activation. It has emerged as a novel target for neurodegenerative diseases.
Role in Disease:
- Regulates microglial activation and neuroinflammation
- Controls B-cell mediated autoimmune responses relevant to MS
- Modulates phagocytosis in myeloid cells
- Involved in TLR signaling
Therapeutic Approaches:
- BTK inhibitors: Tolebrutinib (SAR442168), Evobrutinib
- Central nervous system-penetrant compounds
Clinical Trials:
- Tolebrutinib: Phase II/III trials in MS (peripheral and CNS effects)
- Evobrutinib: Tested in MS and AD
c-Abl is a non-receptor tyrosine kinase involved in cell growth, differentiation, and stress responses. It is activated in Alzheimer's and Parkinson's disease brains.
Role in Disease:
- Promotes tau phosphorylation and aggregation
- Activates autophagy pathways (both beneficial and pathological)
- Contributes to mitochondrial dysfunction
- Mediates oxidative stress responses
Therapeutic Approaches:
- ATP-competitive inhibitors: Imatinib (approved for CML)
- Brain-penetrant second-generation inhibitors
- Allosteric inhibitors
Clinical Evidence:
- Imatinib showed neuroprotective effects in preclinical models
- Safety established but efficacy in neurodegeneration unclear
- Second-generation compounds under development
JNK family members (JNK1, JNK2, JNK3) mediate stress-activated signaling pathways. JNK3 is neuron-specific and particularly implicated in neurodegeneration.
Role in Disease:
- Phosphorylates tau at pathological sites
- Mediates excitotoxicity-induced neuronal death
- Regulates transcription of pro-apoptotic genes
- Controls synaptic plasticity
Therapeutic Approaches:
- JNK3-selective inhibitors
- Peptide inhibitors targeting JNK interaction domains
- Brain-penetrant small molecules
Preclinical Evidence:
- JNK3 knockout mice show neuroprotection
- SP600125 (pan-JNK inhibitor) shows efficacy in PD models
See JNK1 gene page and JNK3 gene page for more details.
flowchart TD
subgraph Alzheimer's_Disease
A"Amyloid-β" -->|"activates"| CDK5
A -->|"activates"| GSK3
CDK5 -->|"phosphorylates"| TAU"Tau Protein"
GSK3 -->|"phosphorylates"| TAU
TAU -->|"aggregates"| NFT"Neurofibrillary Tangles"
A -->|"triggers"| NFkB"p38 MAPK"
NFkB -->|"promotes"| INFL"Neuroinflammation"
CDK5 -->|"activates"| P53"p53"
P53 -->|"induces"| APOP"Apoptosis"
end
subgraph Parkinson's_Disease
MitoD"Mitochondrial Damage" -->|"recruits"| PINK1
PINK1 -->|"activates"| PRKN"Parkin"
PRKN -->|"triggers"| MITO"Mitophagy"
LRRK2"G2019S" -->|"dysregulates"| EL"Endolysosomal Trafficking"
EL -->|"impairs"| AUTOPH"Autophagy"
LRRK2 -->|"activates"| NFkB
NFkB -->|"promotes"| INFL
cAbl" c-Abl" -->|"activates"| AUTOPH
cAbl -->|"phosphorylates"| SNCA"α-Synuclein"
SNCA -->|"aggregates"| LB"Lewy Bodies"
end
subgraph Common_Pathways
OXSTR"Oxidative Stress" -->|"activates"| JNK
JNK -->|"promotes"| APOP
OXSTR -->|"activates"| p38
p38 -->|"mediates"| INFL
end
CDK5 -.->|inhibited by| Roscovitine
GSK3 -.->|inhibited by| Tideglusib
LRRK2 -.->|inhibited by| DNL151
PINK1 -.->|activated by| GeneTherapy
p38 -.->|inhibited by| Losmapimod
JNK -.->|inhibited by| SP600125
cAbl -.->|inhibited by| Imatinib
BTK -.->|inhibited by| Tolebrutinib
style CDK5 fill:#f3e5f5,stroke:#333
style GSK3 fill:#f3e5f5,stroke:#333
style LRRK2 fill:#f3e5f5,stroke:#333
style PINK1 fill:#f3e5f5,stroke:#333
style NFkB fill:#fff9c4,stroke:#333
style JNK fill:#fff9c4,stroke:#333
| Kinase |
Disease Focus |
Drug Candidates |
Development Stage |
Key Challenge |
| CDK5 |
AD, PD |
Roscovitine |
Preclinical |
Brain penetration |
| GSK3α/β |
AD |
Tideglusib |
Phase II |
Safety, efficacy |
| LRRK2 |
PD |
DNL151, GLC-474 |
Phase II |
Selectivity |
| PINK1 |
PD |
Gene therapy |
Preclinical |
Delivery |
| p38α |
AD, MS |
Losmapimod |
Phase II |
Efficacy |
| BTK |
MS, AD |
Tolebrutinib |
Phase II/III |
CNS activity |
| c-Abl |
PD |
Imatinib |
Phase II |
Brain penetration |
| JNK3 |
AD, PD |
SP600125 |
Preclinical |
Isoform selectivity |
Kinases share highly conserved ATP-binding pockets, making selective inhibition challenging. Off-target effects lead to toxicity and limit therapeutic window. Strategies to improve selectivity include:
- Targeting allosteric sites unique to each kinase
- Developing isoform-selective inhibitors
- Using covalent inhibitors for irreversible targeting
The blood-brain barrier (BBB) excludes most kinase inhibitors. Current approaches include:
- Designing compounds with optimal physicochemical properties (MW < 400, LogP 2-4)
- Using prodrug strategies
- Targeting transporter-mediated uptake
- Intranasal delivery systems
See the blood-brain barrier mechanism page for more details.
Many kinase inhibitors show preclinical promise but fail in clinical trials due to:
- Incomplete understanding of disease-relevant pathways
- Compensatory mechanisms negating kinase inhibition
- Inadequate biomarkers for target engagement
- Insufficient patient stratification
Several kinases are implicated across multiple neurodegenerative conditions:
- Neuroinflammation: p38 MAPK, BTK, JNK
- Protein aggregation: CDK5, GSK3, c-Abl
- Mitochondrial dysfunction: PINK1, LRRK2, JNK
- Autophagy dysregulation: LRRK2, c-Abl, GSK3
- Alzheimer's: CDK5, GSK3, p38, JNK
- Parkinson's: LRRK2, PINK1, c-Abl, JNK
- Multiple Sclerosis: BTK, p38
¶ Conclusion and Future Directions
Kinase targeting represents a promising but challenging therapeutic strategy for neurodegenerative diseases. Key success factors include:
- Improved selectivity through structural-based drug design
- Better brain penetration with novel delivery strategies
- Patient stratification based on genetic and biomarker profiles
- Combination therapies targeting multiple kinases or pathways
- Disease-modifying approaches rather than symptomatic relief
The ongoing clinical trials for LRRK2 and BTK inhibitors represent critical tests for the entire field of kinase-targeted neurodegeneration therapy.
- Shomali T, Trempe JF. Targeting of kinases to treat neurodegenerative diseases. Pharmacol Rev. 2026 Feb 26. PMID: 41880688