MAPK9 Protein (JNK2)

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.

Protein Information

Isoforms

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:

JNK2 is activated by dual phosphorylation on Thr183 and Tyr185 by upstream MAP2Ks (MKK4/MKK7).

Normal Function

Stress-Activated Signaling

• Oxidative stress: [ROS](/entities/reactive-oxygen-species), UV radiation
• Cytokine signaling: TNF-α, IL-1β
• Growth factor deprivation
• DNA damage

Signal Transduction Cascade

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

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

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

^[1] Davis RJ. (2000). Signal transduction by the JNK group of MAP kinases. Cell. PMID: 10648792(https://pubmed.ncbi.nlm.nih.gov/10648792/)

^[2] Manning AM, Davis RJ. (2003). Targeting JNK for therapeutic benefit. Nat Rev Drug Discov. PMID: 12858587(https://pubmed.ncbi.nlm.nih.gov/12858587/)

^[3] Pocivavsek A, et al. (2009). JNK activation in Alzheimer disease. J Neurosci Res. PMID: 19301434(https://pubmed.ncbi.nlm.nih.gov/19301434/)

^[4] Ries V, et al. (2016). JNK signaling in Parkinson disease. Neurodegener Dis. PMID: 27055123(https://pubmed.ncbi.nlm.nih.gov/27055123/)

^[5] Centeno C, et al. (2010). Role of JNK in ALS pathogenesis. Brain Res. PMID: 19815014(https://pubmed.ncbi.nlm.nih.gov/19815014/)