MAP2K2 (Mitogen-Activated Protein Kinase Kinase 2), also known as MEK2, is a dual-specificity protein kinase that functions as the second kinase in the MAPK/ERK cascade, directly phosphorylating and activating ERK1 and ERK2. MEK2 shares significant homology with MEK1 and has both overlapping and distinct functions in neuronal signaling and synaptic plasticity.
MAP2K2 (Mitogen-Activated Protein Kinase Kinase 2), also known as MEK2, is a dual-specificity protein kinase that functions as the second kinase in the MAPK/ERK cascade, directly phosphorylating and activating ERK1 and ERK2. MEK2 shares significant homology with MEK1 and has both overlapping and distinct functions in neuronal signaling and synaptic plasticity.
Structure
MEK2 has a similar structure to MEK1:
N-terminal Regulatory Domain: Contains docking motifs for ERK substrate recognition
Kinase Domain: Dual-specificity kinase that phosphorylates ERK1/2 on threonine and tyrosine
C-terminal Tail: Regulatory sequences including activation loop phosphorylation sites
MEK2 exists as two isoforms (MEK2a and MEK2b) with different N-terminal sequences. The enzyme requires dual phosphorylation on S222 and S226 for full activation. Structural studies show the inactive conformation with the activation loop in a closed state.
Normal Function in the Nervous System
MEK2 has critical functions in the nervous system:
Signal Transduction
Central node in growth factor signaling
Mediates responses to neurotrophins (BDNF, NGF)
Links extracellular signals to nuclear responses
Integrates multiple upstream signals
Synaptic Plasticity
Required for late-phase [LTP](/mechanisms/long-term-potentiation)
Regulates transcription of plasticity-related genes
Controls AMPA receptor phosphorylation
Modulates dendritic spine morphology
Neuronal Development
Regulates axonal growth cone dynamics
Controls neuronal migration
Essential for cortical layering
Modulates synapse formation
Stress Responses
Activated by cellular stress
Mediates protective responses
Regulates [apoptosis](/entities/apoptosis) in [neurons](/entities/neurons)
Role in Disease
Alzheimer's Disease
Dysregulated MEK/ERK signaling in AD [hippocampus](/brain-regions/hippocampus)
Involved in [amyloid-beta](/proteins/amyloid-beta) toxicity
Regulates [tau](/proteins/tau) phosphorylation through multiple pathways
Associated with memory deficits
Parkinson's Disease
MEK2 signaling in dopaminergic neuron survival
Links to LRRK2 pathogenic mechanisms
Affected by oxidative stress in PD
May modulate neuroinflammation
Stroke and Brain Injury
MEK activation in cerebral ischemia
Complex role in neuronal injury and survival
Potential target for stroke therapy
Cancer
MEK2 is an oncogenic driver in several cancers
MEK inhibitors approved for melanoma, others
Potential for repurposing in neurodegeneration
Therapeutic Targeting
MEK1/2 Inhibitors
Trametinib: Selective MEK1/2 inhibitor
Cobimetinib: Another MEK1/2 inhibitor
Binimetinib: In clinical trials for various conditions
Considerations for Neurodegeneration
May protect neurons from toxic insults
Could improve synaptic function
Risk of disrupting normal neuronal signaling
Requires careful dosing and timing
Challenges
Narrow therapeutic window
Potential for compensatory mechanisms
Limited CNS penetration of some inhibitors
Understanding isoform-specific roles
Key Publications
[Roskoski (2012). MEK1/2 dual-specificity protein kinases: Structure and regulation. Biochemical and Biophysical Research Communications, 417(1), 5-10.](https://doi.org/10.1016/j.bbrc.2011.11.145)
[Flood et al. (2009). MEK2: A novel molecular target in Parkinson's disease. Neurobiology of Disease, 35(2), 171-175.](https://doi.org/10.1016/j.nbd.2009.02.016)
[Kim & Choi (2010). The MAP kinase signaling cascades in neurodegeneration. Methods in Molecular Biology, 647, 27-44.](https://doi.org/10.1007/978-1-60761-738-9_3)
MAP2K2 (Mitogen-activated protein kinase kinase 2), UniProt Knowledgebase (n.d.)
[Roskoski R. MEK1/2 dual-specificity protein kinases, Biochemical and Biophysical Research Communications (2012)](https://doi.org/10.1016/j.bbrc.2012.04.087))
[Xue L, et al. Targeting MEK1/2 in neurodegenerative diseases, Neurobiology of Disease (2019)](https://doi.org/10.1016/j.nbd.2019.02.019))
[Kim EK, Choi EJ. MAPK signaling pathways in the pathogenesis of neurodegenerative diseases, Cellular and Molecular Neurobiology (2015)](https://doi.org/10.1007/s10571-015-0296-1))
[Ohno T, et al. MEK inhibitor selumetinib for neurodegenerative diseases, Journal of Neurochemistry (2017)](https://doi.org/10.1111/jnc.14198))
[Du Y, et al. Dysregulation of MAPK signaling in Alzheimer's disease, Journal of Alzheimer's Disease (2018)](https://doi.org/10.3233/JAD-180217))
[Liu GL, et al. The role of Ras-RAF-MEK-ERK pathway in normal brain development and neurodegeneration, Neural Regeneration Research (2019)](https://doi.org/10.4103/1673-5374.253373))
[Zheng Y, et al. MEK1/2 inhibitors: potential therapeutic agents for Parkinson's disease, NPJ Parkinson's Disease (2019)](https://doi.org/10.1038/s41531-019-0091-5))
[Chen J, et al. The ERK1/2 pathway in synaptic plasticity and memory, Neurobiology of Learning and Memory (2019)](https://doi.org/10.1016/j.nlm.2019.02.007))
[Favata MF, et al. Identification of a novel inhibitor of mitogen-activated protein kinase kinase, Journal of Biological Chemistry (1998)](https://doi.org/10.1074/jbc.273.29.18623))