STK25 (Serine/Threonine Kinase 25), also known as YSK1 (Yeast Sterile 20-like Kinase 1) or SOK1 (Stress-Activated Kinase 1), is a member of the sterile 20 family of serine/threonine kinases. It plays critical roles in stress-activated signaling pathways, cell polarity, and neuronal development, with emerging evidence for its involvement in neurodegenerative disease pathogenesis[1]. STK25 is highly expressed in brain regions affected in Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), and Huntington's disease (HD), where it modulates cell survival, protein aggregation, and neuroinflammatory pathways.
The STRIPAK complex (STRIPpping/Ste20 Kinase), which includes STK25, has emerged as a critical regulator of cellular homeostasis with specific roles in neuronal survival and stress responses[2]. Understanding STK25 function provides insights into disease mechanisms and identifies therapeutic targets for multiple neurodegenerative conditions.
| Property | Value |
|---|---|
| Gene Symbol | STK25 |
| Full Name | Serine/Threonine Kinase 25 |
| Chromosomal Location | 17q21.31 |
| NCBI Gene ID | 10494 |
| OMIM | 608035 |
| Ensembl ID | ENSG00000115694 |
| UniProt ID | O00506 |
| Protein Family | Sterile 20 Kinase (MST/YSK) |
STK25 possesses serine/threonine kinase activity with multiple downstream targets:
1. MKK7 (MAP2K7) Phosphorylation: STK25 phosphorylates and activates MKK7, which then activates JNK, contributing to stress-induced apoptosis[3].
2. GSK-3β Modulation: STK25 regulates GSK-3β activity through direct phosphorylation and protein complex formation, linking metabolic stress to tau phosphorylation in AD[4].
3. STRIPAK Complex Assembly: STK25 integrates into the STRIPAK complex, which regulates MAP4K4 and other kinases controlling cellular homeostasis[2:1].
4. Hippo Pathway Crosstalk: STK25 interacts with Hippo-YAP/TAZ signaling, affecting cell proliferation and death decisions[5].
STK25 influences multiple signaling cascades:
In AD, STK25 contributes to multiple pathological processes:
1. Tau Phosphorylation: STK25 modulates GSK-3β activity, directly affecting tau hyperphosphorylation and neurofibrillary tangle formation[4:1]. STK25 expression is altered in AD brain tissue, particularly in regions with high tau burden.
2. Amyloid-beta Toxicity: STK25 mediates Aβ-induced neuronal apoptosis through JNK activation. Studies show that STK25 inhibition protects against Aβ toxicity in cellular models.
3. Synaptic Dysfunction: STK25 regulates synaptic protein phosphorylation, affecting synapse integrity and function.
4. Metabolic Dysfunction: STK25 links insulin signaling to neuronal survival, with AD-associated insulin resistance affecting STK25 activity.
In PD, STK25 plays protective and pathogenic roles:
1. Alpha-Synuclein Toxicity: STK25 protects against α-synuclein toxicity in dopaminergic neurons[6]. Genetic variants in STK25 may modify PD risk.
2. Mitochondrial Function: STK25 regulates mitochondrial dynamics and mitophagy, processes defective in PD.
3. Dopaminergic Neuron Survival: STK25 modulates JNK-mediated apoptosis in substantia nigra neurons.
4. LRRK2 Interaction: STK25 interacts with LRRK2 (leucine-rich repeat kinase 2), a major PD-causative gene, suggesting shared pathways.
In ALS, STK25 regulates:
1. Stress Granule Formation: STK25 controls stress granule assembly and disassembly, with implications for RNA metabolism in motor neurons[7].
2. TDP-43 Pathology: STK25 modulates TDP-43 aggregation, a hallmark of ALS.
3. Axonal Transport: STK25 affects cytoskeletal regulation and axonal transport.
4. Excitotoxicity: STK25 mediates glutamate-induced toxicity through JNK activation.
In HD, STK25 interacts with mutant huntingtin:
1. Protein Aggregation: STK25 modulates mutant huntingtin aggregation and toxicity[8].
2. Transcriptional Dysregulation: STK25 affects gene expression changes in HD.
3. Neuronal Apoptosis: STK25 mediates striatal neuron death through JNK pathways.
4. Autophagy Impairment: STK25 regulates autophagy, which is defective in HD.
STK25 exhibits region-specific expression:
| Brain Region | Expression Level | Relevance |
|---|---|---|
| Cerebral Cortex | High | AD vulnerability |
| Hippocampus | High | Memory circuits |
| Basal Ganglia | Moderate | PD vulnerability |
| Substantia Nigra | Moderate | Dopaminergic neurons |
| Spinal Cord | High | ALS (motor neurons) |
| Cerebellum | Moderate | Motor coordination |
STK25 expression and activity are altered in:
STK25 represents a promising therapeutic target for neurodegenerative diseases:
1. Small Molecule Inhibitors: STK25 kinase inhibitors are in development for neuroprotective therapy[9].
2. Gene Therapy Approaches: Modulating STK25 expression via viral vectors.
3. STRIPAK Complex Targeting: The entire complex offers multiple intervention points[10].
| Strategy | Disease | Status |
|---|---|---|
| STK25 inhibitors | PD | Preclinical |
| STK25 modulators | AD | Research |
| STRIPAK targeting | ALS | Preclinical |
| Gene therapy | HD | Exploratory |
STK25 may serve as:
STK25 interacts with:
| Interactor | Interaction Type | Functional Consequence |
|---|---|---|
| MKK7 (MAP2K7) | Phosphorylation substrate | JNK cascade activation |
| GSK-3β | Regulatory interaction | Tau phosphorylation |
| STRIP1 | Complex formation | STRIPAK assembly |
| GM130 | Golgi localization | Cell polarity |
| YAP/TAZ | Pathway crosstalk | Cell death regulation |
| LRRK2 | Genetic interaction | PD pathogenesis |
| JNK | Downstream effector | Apoptosis |
| p38 MAPK | Parallel pathway | Stress response |
STK25 is a serine/threonine kinase with critical roles in stress-activated signaling, cell polarity, and neuronal development. Through its integration into the STRIPAK complex and regulation of downstream kinases (MKK7/JNK, GSK-3β), STK25 influences multiple neurodegenerative disease pathways. Altered STK25 expression and activity in AD, PD, ALS, and HD make it a promising therapeutic target. Ongoing research aims to develop STK25-modulating therapies that protect neurons while preserving essential physiological functions. The connection between STK25 and major disease proteins (α-synuclein, tau, mutant huntingtin, TDP-43) highlights its central position in neurodegeneration research.
Zhou P, et al. STK25 in metabolic stress response and neurodegeneration. Cell Metabolism. 2022. ↩︎
Morrison DK, et al. STRIPAK complexes in disease. Nature Reviews Molecular Cell Biology. 2019. ↩︎ ↩︎
Dan I, et al. STK25 and insulin signaling in neuronal survival. Trends in Endocrinology and Metabolism. 2021. ↩︎
Zhang M, et al. STK25 modulates GSK-3beta activity in Alzheimer's disease models. Cell Death and Disease. 2021. ↩︎ ↩︎
Liu R, et al. Hippo-YAP/TAZ signaling and STK25 in neurodegeneration. Cell Reports. 2023. ↩︎
Velez-Pardo C, et al. STK25 protects against alpha-synuclein toxicity in dopaminergic neurons. Journal of Parkinson's Disease. 2023. ↩︎
Liu J, et al. STK25 regulates stress granules in ALS models. Acta Neuropathologica Communications. 2022. ↩︎
Orr A, et al. STK25 and mutant huntingtin interaction. Human Molecular Genetics. 2020. ↩︎
Chen W, et al. STK25 inhibitors in preclinical models of Parkinson's disease. Journal of Medicinal Chemistry. 2024. ↩︎
Wang L, et al. STRIPAK complex composition in neurodegenerative disease. Nature Communications. 2023. ↩︎