MAPK9 Protein (JNK2)
Introduction
<table class="infobox infobox-protein">
<tr>
<th class="infobox-header" colspan="2">MAPK9 Protein (JNK2)</th>
</tr>
<tr>
<td class="label">Gene</td>
<td>MAPK9</td>
</tr>
<tr>
<td class="label">UniProt ID</td>
<td>Q9Y0S2</td>
</tr>
<tr>
<td class="label">Molecular Weight</td>
<td>48 kDa</td>
</tr>
<tr>
<td class="label">Length</td>
<td>424 amino acids</td>
</tr>
<tr>
<td class="label">Subcellular Localization</td>
<td>Cytoplasm, Nucleus</td>
</tr>
<tr>
<td class="label">Family</td>
<td>MAPK family, JNK subfamily</td>
</tr>
<tr>
<td class="label">Aliases</td>
<td>JNK2, JNK2A, SAPK1A</td>
</tr>
<tr>
<td class="label">Kinase Domain</td>
<td>residues 45-308</td>
</tr>
<tr>
<td class="label">Strategy</td>
<td>Agent</td>
</tr>
<tr>
<td class="label">JNK inhibitors</td>
<td>SP600125, JNK-IN-8</td>
</tr>
<tr>
<td class="label">Peptide inhibitors</td>
<td>TAT-JNK-interacting protein</td>
</tr>
<tr>
<td class="label">Natural compounds</td>
<td>Curcumin, BDMA</td>
</tr>
<tr>
<td class="label">Downstream targets</td>
<td>c-Jun, ATF2</td>
</tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/alzheimer" style="color:#ef9a9a">ALZHEIMER</a>, <a href="/wiki/alzheimer" style="color:#ef9a9a">Alzheimer</a>, <a href="/wiki/ms" style="color:#ef9a9a">Ms</a></td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/a
...MAPK9 Protein (JNK2)
Introduction
<table class="infobox infobox-protein">
<tr>
<th class="infobox-header" colspan="2">MAPK9 Protein (JNK2)</th>
</tr>
<tr>
<td class="label">Gene</td>
<td>MAPK9</td>
</tr>
<tr>
<td class="label">UniProt ID</td>
<td>Q9Y0S2</td>
</tr>
<tr>
<td class="label">Molecular Weight</td>
<td>48 kDa</td>
</tr>
<tr>
<td class="label">Length</td>
<td>424 amino acids</td>
</tr>
<tr>
<td class="label">Subcellular Localization</td>
<td>Cytoplasm, Nucleus</td>
</tr>
<tr>
<td class="label">Family</td>
<td>MAPK family, JNK subfamily</td>
</tr>
<tr>
<td class="label">Aliases</td>
<td>JNK2, JNK2A, SAPK1A</td>
</tr>
<tr>
<td class="label">Kinase Domain</td>
<td>residues 45-308</td>
</tr>
<tr>
<td class="label">Strategy</td>
<td>Agent</td>
</tr>
<tr>
<td class="label">JNK inhibitors</td>
<td>SP600125, JNK-IN-8</td>
</tr>
<tr>
<td class="label">Peptide inhibitors</td>
<td>TAT-JNK-interacting protein</td>
</tr>
<tr>
<td class="label">Natural compounds</td>
<td>Curcumin, BDMA</td>
</tr>
<tr>
<td class="label">Downstream targets</td>
<td>c-Jun, ATF2</td>
</tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/alzheimer" style="color:#ef9a9a">ALZHEIMER</a>, <a href="/wiki/alzheimer" style="color:#ef9a9a">Alzheimer</a>, <a href="/wiki/ms" style="color:#ef9a9a">Ms</a></td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">16 edges</a></td>
</tr>
</table>
Mapk9 Protein (Jnk2) is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.
Overview
MAPK9 (Mitogen-Activated Protein Kinase 9), also known as JNK2 (c-Jun N-terminal Kinase 2), is a serine/threonine protein kinase that plays central roles in stress signaling, inflammation, cell proliferation, and [apoptosis](/entities/apoptosis). JNK2 is one of three JNK isoforms (JNK1, JNK2, JNK3) and is widely expressed in most tissues, including the brain. Unlike JNK3, which is neuron-specific, JNK2 is expressed in [neurons](/entities/neurons) and glia.
MAPK9 has multiple isoforms due to alternative splicing:
- JNK2α1: Full-length isoform (424 aa)
- JNK2α2: Alternative splice variant
- JNK2β1, β2: Additional variants
Structure
The JNK2 protein contains:
Kinase domain (KD): Catalytic core with ATP-binding site
Docking domain (D-domain): For substrate and upstream kinase binding
Transactivation domain (TAD): For interacting with transcription factorsJNK2 is activated by dual phosphorylation on Thr183 and Tyr185 by upstream MAP2Ks (MKK4/MKK7).
Normal Function
Stress-Activated Signaling
JNK2 responds to various cellular stresses:
- Oxidative stress: [ROS](/entities/reactive-oxygen-species), UV radiation
- Cytokine signaling: TNF-α, IL-1β
- Growth factor deprivation
- DNA damage
Signal Transduction Cascade
The JNK pathway follows:
Key Targets
- c-Jun: AP-1 transcription factor component
- ATF2: Activating transcription factor 2
- ELK1: ETS domain-containing protein
- p53: Tumor suppressor
- Bim, Bad: Pro-apoptotic proteins
Expression Pattern
MAPK9 is expressed in:
- Brain: [Cortex](/brain-regions/cortex), [hippocampus](/brain-regions/hippocampus), basal ganglia, cerebellum
- Immune cells: T cells, B cells, macrophages
- Peripheral tissues: Heart, liver, lung, kidney
In neurons, JNK2 is localized in both cytosolic and nuclear compartments.
Role in Neurodegeneration
Alzheimer Disease
JNK2 plays complex roles in AD pathogenesis:
- Amyloid-β toxicity: JNK2 is activated by [Aβ](/proteins/amyloid-beta) and contributes to synaptic dysfunction
- [Tau](/proteins/tau) phosphorylation: JNK2 can phosphorylate [tau](/proteins/tau) at multiple sites (Thr181, Ser202, Thr231)
- Neuroinflammation: JNK2 mediates cytokine-induced neuroinflammation
- Synaptic plasticity: JNK2 regulates AMPA receptor trafficking and [LTP](/mechanisms/long-term-potentiation)
- Neuronal apoptosis: JNK2 activation can lead to caspase-dependent cell death
JNK2/3 deficiency protects against Aβ toxicity in mouse models.
Parkinson Disease
JNK2 contributes to PD pathogenesis:
- Dopaminergic neuron death: JNK2 activation in substantia nigra pars compacta
- Mitochondrial dysfunction: JNK2 links mitochondrial stress to apoptosis
- [α-Synuclein](/proteins/alpha-synuclein) toxicity: JNK2 may phosphorylate α-syn and promote aggregation
- Neuroinflammation: JNK2 mediates microglial activation
Amyotrophic Lateral Sclerosis
- Motor neuron degeneration: JNK2/3 activation in SOD1 models
- Glial activation: JNK2 in [astrocytes](/entities/astrocytes) and [microglia](/entities/microglia)
- Potential therapeutic target
Stroke and Brain Injury
- Ischemic injury: JNK2 activation in stroke models
- Traumatic brain injury: JNK2 contributes to secondary damage
- Neuroprotective strategies: JNK inhibitors in clinical trials
Therapeutic Implications
Challenges: JNK2 has both protective and pathogenic roles; complete inhibition may have adverse effects.
Research Directions
- Developing brain-penetrant selective JNK2 inhibitors
- Understanding isoform-specific functions
- Biomarkers for JNK2 activity
- Combination with other pathway modulators
See Also
- [MAPK9 Gene](/proteins/mapk9-protein)
- [MAPK8 Protein (JNK1)](/proteins/mapk8-protein)
- [MAPK10 Protein (JNK3)](/proteins/mapk10-protein)
- [JNK Signaling Pathway](/mechanisms/jnk-signaling-pathway)
- [Alzheimer Disease](/diseases/alzheimers-disease)
- [Parkinson Disease](/diseases/parkinsons-disease)
- [Neuroinflammation Pathway](/mechanisms/neuroinflammation-pathway)
External Links
- [UniProt: MAPK9](https://www.uniprot.org/uniprot/Q9Y0S2)
- [PDB: JNK2](https://www.rcsb.org/structure/1JNK)
- [Kegg: MAPK9](https://www.kegg.jp/kegg-bin/show_pathway?map=map04010)
Background
The study of Mapk9 Protein (Jnk2) has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.
Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.
References
<sup>[1]</sup> Davis RJ. (2000). Signal transduction by the JNK group of MAP kinases. Cell. PMID: 10648792(https://pubmed.ncbi.nlm.nih.gov/10648792/)
<sup>[2]</sup> Manning AM, Davis RJ. (2003). Targeting JNK for therapeutic benefit. Nat Rev Drug Discov. PMID: 12858587(https://pubmed.ncbi.nlm.nih.gov/12858587/)
<sup>[3]</sup> Pocivavsek A, et al. (2009). JNK activation in Alzheimer disease. J Neurosci Res. PMID: 19301434(https://pubmed.ncbi.nlm.nih.gov/19301434/)
<sup>[4]</sup> Ries V, et al. (2016). JNK signaling in Parkinson disease. Neurodegener Dis. PMID: 27055123(https://pubmed.ncbi.nlm.nih.gov/27055123/)
<sup>[5]</sup> Centeno C, et al. (2010). Role of JNK in ALS pathogenesis. Brain Res. PMID: 19815014(https://pubmed.ncbi.nlm.nih.gov/19815014/)