MAPK7 (Mitogen-Activated Protein Kinase 7), also known as ERK5 (Extracellular Signal-Regulated Kinase 5), is a serine/threonine protein kinase that plays critical roles in neuronal development, synaptic plasticity, cell survival, and stress responses. As part of the MAPK signaling cascade, MAPK7 integrates extracellular signals to regulate gene expression and cellular responses relevant to neurodegenerative disease pathogenesis.
The MAPK signaling pathways are central regulators of cellular responses to growth factors, stress, and inflammatory signals. MAPK7/ERK5 is unique among MAPK family members due to its distinctive N-terminal domain and specific biological functions. In the central nervous system, MAPK7 is essential for neurogenesis, neuronal differentiation, synaptic plasticity, and memory formation. Dysregulation of MAPK7 signaling contributes to the pathogenesis of Alzheimer's disease, Parkinson's disease, and other neurodegenerative disorders.
| Mitogen-Activated Protein Kinase 7 |
|---|
| Gene Symbol | MAPK7 |
| Full Name | Mitogen-Activated Protein Kinase 7 (ERK5) |
| Chromosome | 17p11.2 |
| NCBI Gene ID | [5598](https://www.ncbi.nlm.nih.gov/gene/5598) |
| OMIM | 602534 |
| Ensembl ID | ENSG00000166401 |
| UniProt ID | [Q13115](https://www.uniprot.org/uniprot/Q13115) |
MAPK7/ERK5 is activated by upstream MAPKKs, specifically MEK5, which phosphorylates ERK5 at TEY motif within its activation loop . Unlike other MAPK family members, ERK5 has a unique N-terminal region that mediates protein-protein interactions and transcriptional co-activation functions.
The MAPK7 signaling cascade consists of:
- MEKK2/3 - MAPKKK that activates MEK5
- MEK5 - Specific MAPKK for ERK5
- MAPK7/ERK5 - The terminal kinase
ERK5 phosphorylates multiple downstream targets including:
- MEF2 (myocyte enhancer factor 2) transcription factors
- c-Fos, c-Myc
- Bad (pro-apoptotic protein)
- GSK-3β
In neurons, MAPK7/ERK5 regulates :
- Neurogenesis: Controls neural progenitor cell proliferation and differentiation
- Synaptic plasticity: Essential for long-term potentiation (LTP) and memory formation
- Neuronal survival: Mediates neurotrophic factor signaling (BDNF, NGF)
- Stress responses: Activated by oxidative stress, excitotoxicity, and neuroinflammation
MAPK7 is widely expressed in the brain with high levels in :
- Hippocampus (CA1-CA3 regions)
- Cerebral cortex (layers II-IV)
- Cerebellum (Purkinje cells)
- Substantia nigra (dopaminergic neurons)
- Basal forebrain cholinergic neurons
MAPK7/ERK5 signaling is profoundly dysregulated in Alzheimer's disease :
- Amyloid-beta pathology: Aβ oligomers inhibit MAPK7 signaling in neurons, contributing to synaptic dysfunction and memory deficits
- Tau phosphorylation: MAPK7 can phosphorylate tau at certain residues, potentially linking Aβ to tau pathology
- Synaptic failure: Impaired ERK5 signaling contributes to synaptic loss and cognitive decline
- Neurotrophic support: BDNF-mediated neuroprotective signaling through ERK5 is compromised in AD
- Therapeutic targeting: ERK5 activators are being investigated as potential AD therapeutics
MAPK7 plays complex roles in PD pathogenesis :
- Dopaminergic neuron survival: ERK5 mediates survival signaling in substantia nigra neurons
- Alpha-synuclein toxicity: MAPK7 activation can modify neuronal responses to alpha-synuclein aggregation
- Mitochondrial dysfunction: ERK5 signaling intersects with mitochondrial quality control pathways
- Neuroinflammation: Glial ERK5 activation can modulate neuroinflammatory responses
ERK5 dysregulation contributes to motor neuron degeneration in ALS:
- Excitotoxicity: ERK5 signaling modulates glutamate receptor expression and excitotoxic cell death
- Axonal degeneration: Impaired ERK5 signaling affects axonal stability
- Protein aggregation: ERK5 activation can influence TDP-43 pathology
¶ Stroke and Ischemia
ERK5 has dual roles in ischemic brain injury :
- Acute phase: Rapid ERK5 activation in neurons is protective against ischemic damage
- Delayed phase: Sustained ERK5 activation in glial cells can promote inflammation
MAPK7 represents a therapeutic target for neurodegenerative diseases:
- ERK5 activators: Small molecules that enhance ERK5 signaling for neuroprotection
- MEK5-ERK5 pathway modulators: Target the upstream activator
- BDNF mimetics: Exploit the ERK5-mediated neurotrophic pathway
Key interacting partners include :
- MEK5 (upstream activator)
- MEF2A/C/D (transcription factor substrates)
- PTEN (phosphatase that negatively regulates ERK5)
- GADD45 (stress-responsive protein)
- SGK1 (serum/glucocorticoid-regulated kinase)