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MAP2K5
MAP2K5 (MEK5)
Gene Overview
<div class="infobox infobox-gene">
<div class="infobox-header">Gene Information</div>
<table>
<tr><th>Symbol</th><td>MAP2K5</td></tr>
<tr><th>Full Name</th><td>Mitogen-Activated Protein Kinase Kinase 5</td></tr>
<tr><th>Alias</th><td>MEK5</td></tr>
<tr><th>Chromosome</th><td>15q23</td></tr>
<tr><th>NCBI Gene ID</th><td>5608</td></tr>
<tr><th>UniProt ID</td><td>Q13131</td></tr>
<tr><th>Ensembl ID</th><td>ENSG00000108691</td></tr>
<tr><th>Protein Family</th><td>MAP kinase kinase (MEK) family</td></tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/als" style="color:#ef9a9a">Als</a>, <a href="/wiki/amyotrophic-lateral-sclerosis" style="color:#ef9a9a">Amyotrophic Lateral Sclerosis</a></td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">6 edges</a></td>
</tr>
</table>
</div>
Introduction
MAP2K5 (also known as MEK5) encodes mitogen-activated protein kinase kinase 5, a dual-specificity protein kinase that serves as the specific upstream activator of ERK5 (also known as Big MAP Kinase 1, BMK1). The MAP2K5-ERK5 signaling axis represents a distinct MAPK cascade that plays critical roles in neuronal development, synaptic plasticity, cell survival, and stress responses. Unlike other MAP kinase pathways, the MEK5-ERK5 pathway has unique functions in the nervous system that are particularly relevant to neurodegenerative disease pathogenesis and neuroprotection.
MAP2K5 (MEK5)
Gene Overview
<div class="infobox infobox-gene">
<div class="infobox-header">Gene Information</div>
<table>
<tr><th>Symbol</th><td>MAP2K5</td></tr>
<tr><th>Full Name</th><td>Mitogen-Activated Protein Kinase Kinase 5</td></tr>
<tr><th>Alias</th><td>MEK5</td></tr>
<tr><th>Chromosome</th><td>15q23</td></tr>
<tr><th>NCBI Gene ID</th><td>5608</td></tr>
<tr><th>UniProt ID</td><td>Q13131</td></tr>
<tr><th>Ensembl ID</th><td>ENSG00000108691</td></tr>
<tr><th>Protein Family</th><td>MAP kinase kinase (MEK) family</td></tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/als" style="color:#ef9a9a">Als</a>, <a href="/wiki/amyotrophic-lateral-sclerosis" style="color:#ef9a9a">Amyotrophic Lateral Sclerosis</a></td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">6 edges</a></td>
</tr>
</table>
</div>
Introduction
MAP2K5 (also known as MEK5) encodes mitogen-activated protein kinase kinase 5, a dual-specificity protein kinase that serves as the specific upstream activator of ERK5 (also known as Big MAP Kinase 1, BMK1). The MAP2K5-ERK5 signaling axis represents a distinct MAPK cascade that plays critical roles in neuronal development, synaptic plasticity, cell survival, and stress responses. Unlike other MAP kinase pathways, the MEK5-ERK5 pathway has unique functions in the nervous system that are particularly relevant to neurodegenerative disease pathogenesis and neuroprotection.
The MEK5 protein consists of 471 amino acids and contains a kinase domain with characteristic motifs required for dual-specificity phosphorylation. MEK5 is distinguished from other MAP2K family members (MEK1/2, MEK3/6, MEK4/7) by its highly specific substrate specificity for ERK5, as it does not efficiently phosphorylate other MAPKs. This specificity makes MEK5 a critical regulator of ERK5-mediated signaling in neurons and glia.
The MAPK/ERK5 Signaling Pathway
Pathway Architecture
The MAP2K5-ERK5 pathway constitutes one of five major MAPK cascades in mammalian cells:[@cavalli2023]
Upstream Regulators
MAP2K5 is activated by MAPKKK proteins, primarily MEKK2 (MAP3K2) and MEKK3 (MAP3K3), which respond to various extracellular signals:[@nithianandarajahjones2022]
- Growth factors: BDNF, NGF, EGF
- Cellular stress: Oxidative stress, endoplasmic reticulum stress
- Synaptic activity: Glutamate receptor activation
- Inflammatory signals: Cytokine signaling in glia
Downstream Targets
Activated ERK5 phosphorylates multiple transcription factors and effectors:[@lim2022]
- MEF2 family: Myocyte enhancer factor 2 (MEF2A-D)
- CREB: cAMP response element-binding protein
- c-Fos: Immediate early gene product
- SGK: Serum- and glucocorticoid-induced kinase
- BIM: Pro-apoptotic Bcl-2 family protein
Biological Functions in the Nervous System
Neuronal Development
MAP2K5-ERK5 signaling is essential for multiple aspects of brain development:[@peyrachel2019]
Axon Growth and Guidance:
- Regulates axonal extension and branching
- Controls growth cone dynamics
- Mediates guidance cue responses
- Essential for proper circuit formation
- Promotes neuronal fate specification
- Controls dendritic arborization
- Regulates synapse formation
- Essential for cortical development
Synaptic Plasticity
The MEK5-ERK5 pathway plays critical roles in learning and memory:[@harada2021][@tang2021]
Long-Term Potentiation (LTP):
- Required for LTP induction in hippocampal neurons
- Controls AMPA receptor trafficking
- Regulates spine morphogenesis
- Mediates activity-dependent gene expression
- ERK5 activation in hippocampus during memory tasks
- CREB phosphorylation and gene transcription
- Consolidation of synaptic changes
- Long-term memory stability
Neuroprotection
MEK5-ERK5 signaling mediates neuroprotective responses:[@finegan2021][@sun2023]
Oxidative Stress Response:
- Activation of antioxidant gene expression
- Protection against ROS-induced cell death
- Maintenance of mitochondrial function
- Upregulation of survival proteins
- ERK5 is downstream of TrkB receptor
- Mediates BDNF's neuroprotective effects
- Promotes neuronal survival in injury models[@zhao2023]
- Essential for trophic factor signaling
- Phosphorylation and inhibition of pro-apoptotic BIM
- Activation of MEF2-dependent survival genes
- Cross-talk with PI3K/Akt pathway
- Regulation of caspase activity
Mitochondrial Function
ERK5 regulates mitochondrial biology in neurons:[@yan2019]
- Controls mitochondrial biogenesis
- Regulates mitochondrial dynamics (fusion/fission)
- Maintains mitochondrial membrane potential
- Protects against mitochondrial apoptosis
Disease Associations
Alzheimer's Disease
The MEK5-ERK5 pathway is implicated in multiple aspects of AD pathogenesis:[@wang2022][@johnson2019]
Amyloid-Beta Effects:
- Aβ induces ERK5 activation in neurons
- Paradoxically, ERK5 activation can be both protective and detrimental
- MEK5-ERK5 signaling in microglial activation
- Regulation of inflammatory responses
- ERK5 can phosphorylate tau at multiple sites
- GSK-3β and ERK5 collaboration in tau hyperphosphorylation
- Role in tau aggregation and spread
- Therapeutic targeting considerations
- ERK5 is required for synaptic plasticity deficits in AD models
- Memory consolidation impairments
- dendritic spine loss mechanisms
- MEK5 inhibitors as AD therapeutic strategy
- Targeting ERK5 activation to reduce neuroinflammation
- Modulating tau pathology through ERK5
Parkinson's Disease
MAP2K5-ERK5 signaling is relevant to PD pathophysiology:[@chen2020]
Dopaminergic Neuron Survival:
- ERK5 activation protects dopaminergic neurons
- Neuroprotective effects against oxidative stress
- Response to mitochondrial toxins (MPTP, 6-OHDA)
- Role in L-DOPA-induced dyskinesia
- ERK5 activation in response to α-synuclein aggregation
- Potential role in protein clearance pathways
- Involvement in cellular stress responses
- MEK5-ERK5 modulators for PD treatment
- Neuroprotection strategies
Amyotrophic Lateral Sclerosis
Recent research has identified MEK5-ERK5 in ALS:[@zhang2023]
Motor Neuron Survival:
- MEK5 is protective in SOD1 models
- ERK5 activation promotes survival
- Cross-talk with other survival pathways
- Targeting MEK5 as ALS therapeutic strategy
Other Neurodegenerative Conditions
Huntington's Disease:
- ERK5 dysregulation in HD models
- Role in mutant huntingtin toxicity
- Therapeutic targeting potential
- ERK5 activation in ischemic preconditioning
- Neuroprotection in stroke models
- Recovery and plasticity mechanisms
Expression Patterns
Brain Expression
MAP2K5 is widely expressed in the brain:
- High expression: Hippocampus (CA1-3, dentate gyrus), cerebral cortex, cerebellum
- Cellular localization: Neurons (soma, dendrites, synapses), some glial cells
- Developmental regulation: Higher expression during development
- Activity-dependent: Synaptic activity modulates expression
Cell Type Specificity
- Neurons: Primary expression in excitatory and inhibitory neurons
- Astrocytes: Lower expression, upregulated in injury
- Microglia: Inducible expression in activated states
- Oligodendrocytes: Present in myelin-producing cells
Genetic Variants
Known Variants
MAP2K5 genetic variants have been associated with:
- Psychiatric disorders: Depression, antidepressant response[@stuart2021]
- Neurological conditions: Stroke susceptibility
- Cancer: Some somatic mutations in tumors
- Development: Rare developmental disorders
Clinical Significance
- Pharmacogenomics of MEK inhibitors
- Predictors of treatment response
- Potential biomarker applications
Therapeutic Implications
MEK5 as Drug Target
The specificity of MEK5 for ERK5 makes it an attractive target:[@li2022]
Small Molecule Inhibitors:
- BIX02188: Selective MEK5 inhibitor
- BIX02189: MEK5 inhibitor
- Compound 43: ERK5 inhibitor
- Neurodegeneration prevention
- Cancer therapy (brain penetrant versions)
- Inflammatory conditions
Challenges
- Blood-brain barrier penetration
- Optimal timing of intervention
- Pathway compensation mechanisms
Research Directions
Unresolved Questions
Emerging Areas
- Single-cell studies: Cell-type specific ERK5 functions
- Optogenetics: Light-controlled ERK5 activation
- Biomarkers: ERK5 activity as disease biomarker
- Combination therapy: MEK5 modulation with other targets
Protein Structure and Function
Structural Features
The MEK5 protein contains several key structural features essential for its function:
Kinase Domain:
- Dual-specificity protein kinase domain (residues 50-300)
- ATP-binding site in the active site cleft
- Phosphorylation sites for activation (S218, T222)
- DFG motif for substrate recognition
- N-terminal docking domain for ERK5 interaction
- C-terminal region for protein-protein interactions
- Nuclear localization signals
- Nuclear export signals
- MEK5α: Full-length isoform (471 aa)
- MEK5β: Truncated isoform lacking N-terminal region
- Different tissue distribution and function
Catalytic Mechanism
MEK5 phosphorylates ERK5 through a canonical kinase mechanism:
Protein-Protein Interactions
MEK5 interacts with multiple proteins to execute its functions:
- MEKK2/3: Upstream MAPKKK activators
- ERK5: Primary substrate
- ERK5 nuclear carriers: Chaperones for nuclear import
- Phosphatases: MKP5, MKP7 for pathway termination
- Scaffold proteins: KSR for pathway optimization
Animal Models
Knockout Studies
MAP2K5 knockout mice have provided insights into its functions:
MEK5 Knockout:
- Embryonic lethality around E9.5-10.5
- Defects in heart development
- Impaired neuronal development
- Vascular abnormalities
- Neuron-specific deletion: Learning and memory deficits
- Glia-specific deletion: Altered inflammatory responses
- Muscle-specific deletion: Metabolic phenotypes
Transgenic Models
Transgenic and knock-in models have been developed:
ERK5 Transgenic:
- Neuronal ERK5 overexpression: Enhanced LTP
- Constitutive ERK5: Developmental abnormalities
- Dominant-negative ERK5: Impaired memory
- AD models with MEK5 modulation: Altered pathology
- PD models with MEK5 manipulation: Changed outcomes
- Stroke models: Ischemic preconditioning effects
Behavioral Studies
MEK5-ERK5 signaling in behavior:
Learning and Memory:
- MEK5/ERK5 knockouts: Impaired spatial memory
- Constitutive activation: Enhanced memory
- Specific brain region manipulation: Distinct effects
- Cerebellar MEK5: Motor coordination
- Basal ganglia: Habit formation
- Motor neuron ERK5: Function in ALS models
- Depression-related behaviors
- Anxiety-like behaviors
- Response to stress
Signaling Pathway Integration
Cross-talk with Other MAPK Pathways
MEK5-ERK5 interacts with other MAPK cascades:
ERK1/2 Pathway:
- Parallel activation by growth factors
- Shared downstream targets (CREB)
- Distinct temporal patterns
- Different cellular outcomes
- Often opposing functions
- Stress-activated vs growth factor activated
- Cell fate decisions: survival vs death
- Coordination in development
- Similar stress-activated pattern
- Common substrates
- Complementary functions
Integration with Other Signaling
MEK5-ERK5 integrates with multiple pathways:
cAMP/PKA:
- Cross-activation of CREB
- Shared target genes
- Modulation by cAMP
- Co-activation by growth factors
- Parallel survival signaling
- Intersection at BAD phosphorylation
- Activity-dependent activation
- Calmodulin interactions
- Activity-dependent transcription
Spatial Signaling
MEK5-ERK5 has distinct spatial pools:
Nuclear ERK5:
- Transcriptional regulation
- Gene expression programs
- Long-term effects
- Cytoskeletal effects
- Immediate responses
- Local signaling
- Synaptic plasticity
- Local translation
- Spine function
Clinical Perspectives
Biomarker Potential
ERK5 activity as a biomarker:
Diagnostic:
- Disease state identification
- Subtype classification
- Progression monitoring
- Outcome prediction
- Treatment response
- Survival markers
- Target engagement
- Pathway modulation
- Efficacy measures
Therapeutic Development
MEK5-ERK5 pathway targeting strategies:
Direct MEK5 Modulators:
- Agonists for neuroprotection
- Antagonists for specific contexts
- Isoform-specific compounds
- Direct ERK5 inhibitors
- Allosteric modulators
- Substrate competitors
- With other neuroprotective agents
- With anti-inflammatory drugs
- With disease-modifying therapies
Clinical Trials
Current status of MEK5-ERK5 targeted therapies:
- Preclinical validation ongoing
- CNS-penetrant compounds in development
- Biomarker development for patient selection
- Combination trial designs in planning
Biochemical Properties
Enzyme Kinetics
Substrate Specificity:
- High specificity for ERK5
- Km for ERK5: ~0.5 μM
- Vmax: ~100 pmol/min/mg
- Autophosphorylation on activation loop
- Feedback phosphorylation by ERK5
- Phosphatase-mediated deactivation
Post-Translational Modifications
Phosphorylation:
- S218 and T222: Activation loop phosphorylation
- Multiple serine/threonine sites for regulation
- Acetylation: Affects kinase activity
- Ubiquitination: Protein turnover
- Sumoylation: Localization changes
Protein Complexes
MEK5 is found in various complexes:
Signaling Complexes:
- MEKK2/3-MEK5-ERK5 modules
- Scaffold protein complexes (KSR)
- Nuclear import complexes
- Transcription factor complexes
- Mitochondrial complexes
- Synaptic complexes
Evolutionary Conservation
Species Conservation
MAP2K5 is evolutionarily conserved:
- Mammals: Highly conserved (95%+ identity)
- Birds: ~85% identity
- Fish: ~70% identity
- Drosophila: Homolog DSOR1
- C. elegans: Homolog mek-2
Functional Conservation
The MEK5-ERK5 pathway is functionally conserved across species:
- Developmental functions
- Stress responses
- Synaptic plasticity
Pathophysiological Mechanisms
Oxidative Stress
MEK5-ERK5 in oxidative stress:
Direct Effects:
- ROS activates MEKK2/3
- MEK5-ERK5 activation
- Antioxidant gene expression
- Mitochondrial protection
- DNA damage repair
- Protein homeostasis
Endoplasmic Reticulum Stress
The pathway in ER stress:
- IRE1-MEKK2-MEK5-ERK5 axis
- Unfolded protein response
- Cell survival signaling
Mitochondrial Dysfunction
ERK5 in mitochondrial health:
- Biogenesis regulation
- Dynamics control
- Quality control pathways
- Apoptosis regulation
Treatment Approaches
Pharmacological Modulation
Activators:
- Brain-penetrant MEK5 agonists
- Upstream receptor agonists
- Exercise mimetics
- Selective MEK5 inhibitors
- ERK5 inhibitors
- Combination approaches
Non-Pharmacological
Lifestyle Interventions:
- Exercise enhances ERK5
- Dietary factors
- Stress management
- Gene therapy
- Cell-based therapy
- Optogenetic stimulation
Future Directions
Research Priorities
Therapeutic Potential
- Neuroprotection in AD/PD
- Stroke prevention
- ALS treatment
- Traumatic brain injury
Interactions with Other Proteins
Kinase Interactions
MEK5 interacts with multiple kinases:
Upstream Kinases:
- MEKK2 (MAP3K2): Primary activator
- MEKK3 (MAP3K3): Alternative activator
- TAK1 (MAP3K7): Stress-activated
- Potential cross-talk with MEK1/2
- Shared upstream regulators
- Parallel pathway interaction
Non-Kinase Interactions
Transcription Factors:
- MEF2 family: Primary ERK5 targets
- CREB: Phosphorylation target
- c-Fos: Induction target
- KSR: Scaffold for MAPK cascade
- JIP proteins: Alternative scaffolds
- MP1: Endosomal scaffolding
- Phosphatases: MKP5, MKP7
- Ubiquitin ligases: Degradation control
- Chaperones: Protein folding
Disease Mechanisms
Neurodegeneration Initiation
MEK5-ERK5 in disease onset:
Early Events:
- Subtle synaptic changes
- Early mitochondrial dysfunction
- Initial transcriptional changes
- Sustained pathway dysregulation
- Inflammatory response activation
- Protein aggregation interaction
Cellular Vulnerability
Neuronal vulnerability factors:
Intrinsic Factors:
- High metabolic demand
- Limited regenerative capacity
- Excitable state sensitivity
- [Neuroinflammation](/mechanisms/neuroinflammation) Glial support changes
- Vascular factors
Therapeutic Target Considerations
Target Validation
Evidence supporting MEK5 as target:
- Pathway activation in disease models
- Neuroprotective effects of pathway activation
- Correlation with disease severity
Drug Development Challenges
Chemistry Challenges:
- Achieving brain penetration
- Maintaining selectivity
- Balancing agonist vs antagonist effects
- Complex temporal requirements
- Cell-type specificity needs
- Pathway compensation issues
Combination Strategies
Rationale for combinations:
- MEK5 + other neuroprotective pathways
- MEK5 + anti-inflammatory approaches
- MEK5 + disease-modifying agents
Models and Systems
In Vitro Models
Cell culture systems for studying MEK5:
Primary Neurons:
- Hippocampal neurons: Synaptic plasticity studies
- Cortical neurons: Development studies
- Dopaminergic neurons: PD models
- PC12 cells: Differentiation studies
- SH-SY5Y: Neurodegeneration models
- N2A cells: Molecular mechanisms
In Vivo Models
Animal models for MEK5-ERK5:
Mouse Models:
- Conditional knockouts
- Transgenic overexpression
- Disease model crosses
- Developmental studies
- CNS visualization
- Drug screening
Organoid Systems
Human models:
- Brain organoids: Development
- Disease-specific iPSCs
- Microfluidic devices
Measurement and Detection
Activity Assays
Measuring MEK5-ERK5 activity:
Kinase Assays:
- In vitro kinase assays
- Immunoprecipitation kinase assays
- Fluorescence-based detection
- Phospho-ERK5 antibodies
- Activity-based probes
- Reporter constructs
Expression Analysis
Measuring expression:
mRNA:
- qRT-PCR
- RNAseq
- In situ hybridization
- Western blot
- Immunohistochemistry
- ELISA
See Also
- [ERK5 Signaling Pathway](/mechanisms/erk5-signaling-pathway)
- [MAPK Signaling in Neurodegeneration](/mechanisms/mapk-signaling-neurodegeneration)
- [Neuroprotection Mechanisms](/mechanisms/neuroprotection-mechanisms)
- [Alzheimer's Disease](/diseases/alzheimers-disease)
- [Parkinson's Disease](/diseases/parkinsons-disease)
- [BDNF Signaling](/mechanisms/bdnf-signaling-pathway)
Allen Brain Atlas Data
Gene Expression
MEK5 (MAP2K5) shows moderate expression in:
- Cerebral cortex - Layer 5 pyramidal neurons
- Hippocampus - CA1 and CA3 regions
- Cerebellum - Purkinje cells
- Olfactory bulb - Mitral cells
Brain Region Expression Levels
| Region | Expression Level | Data Source |
|--------|-----------------|--------------|
| Cerebral cortex | Medium | Mouse Brain Atlas |
| Hippocampus | Medium | Mouse Brain Atlas |
| Cerebellum | Low-Medium | Human MTG |
Single-Cell Expression
Single-cell RNA sequencing shows MAP2K5 expression in:
- Pyramidal neurons
- Purkinje cells
- Some interneurons
External Resources
- [Allen Brain Atlas - MAP2K5 Expression](https://portal.brain-map.org/)
- [Allen Brain Cell Atlas](https://portal.brain-map.org/explore/classes/nucleus)
References
External Links
- [NCBI Gene - MAP2K5](https://www.ncbi.nlm.nih.gov/gene/5608)
- [UniProt - Q13131](https://www.uniprot.org/uniprot/Q13131)
- [Ensembl - ENSG00000108691](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000108691)
- [KEGG Pathway - MAPK signaling](https://www.genome.jp/kegg/pathway/map04010.html)
- [PubMed](https://pubmed.ncbi.nlm.nih.gov/)
▸Metadataorigin_type: v1_polymorphic_backfill
| slug | genes-map2k5 |
| kg_node_id | MAP2K5 |
| entity_type | gene |
| origin_type | v1_polymorphic_backfill |
| source_table | wiki_pages |
| wiki_page_id | wp-f89c3f182614 |
| __merged_from | {'merged_at': '2026-05-13', 'unprefixed_id': 'genes-map2k5'} |
| _schema_version | 1 |
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