MAPK8 Gene

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MAPK8 Gene

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MAPK8 Gene

<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">mapk8</th>
</tr>
<tr>
<td class="label">Symbol</td>
<td>MAPK8</td>
</tr>
<tr>
<td class="label">Full Name</td>
<td>Mitogen-Activated Protein Kinase 8</td>
</tr>
<tr>
<td class="label">Alternative Name</td>
<td>JNK1</td>
</tr>
<tr>
<td class="label">Chromosomal Location</td>
<td>10q11.22</td>
</tr>
<tr>
<td class="label">NCBI Gene ID</td>
<td>5599</td>
</tr>
<tr>
<td class="label">Ensembl ID</td>
<td>ENSG00000106789</td>
</tr>
<tr>
<td class="label">UniProt ID</td>
<td>P45985</td>
</tr>
<tr>
<td class="label">Gene Family</td>
<td>MAPK (Mitogen-Activated Protein Kinases)</td>
</tr>
<tr>
<td class="label">Isoform</td>
<td>Molecular Weight</td>
</tr>
<tr>
<td class="label">JNK1α1</td>
<td>46 kDa</td>
</tr>
<tr>
<td class="label">JNK1α2</td>
<td>46 kDa</td>
</tr>
<tr>
<td class="label">JNK1β1</td>
<td>55 kDa</td>
</tr>
<tr>
<td class="label">JNK1β2</td>
<td>55 kDa</td>
</tr>
<tr>
<td class="label">Function</td>
<td>Mechanism</td>
</tr>
<tr>
<td class="label">Stress response</td>
<td>Phosphorylates c-Jun, ATF2, ELK1</td>
</tr>
<tr>
<td class="label">[Apoptosis](/mechanisms/apoptosis-pathway)</td>
<td>Pro-apoptotic via BIM, PUMA, Bax</td>
</tr>
<tr>
<td class="label">Inflammation</td>
<td>Activates [NF-κB](/mechanisms/nf-kb-pathway) pathway</td>
</tr>
<tr>
<td class="label">Synaptic plasticity</td>
<td>Regulates dendritic spine morphology</td>
</tr>
<tr>
<td class="label">Learning and memory</td>
<td>Contextual fear conditioning</td>
</tr>
<tr>
<td class="label">Target</td>
<td>Function</td>
</tr>
<tr>
<td class="label">c-Jun</td>
<td>Transcription factor (AP-1)</td>
</tr>
<tr>
<td class="label">JunB</td>
<td>AP-1 transcription factor</td>
</tr>
<tr>
<td class="label">ATF2</td>
<td>Transcription factor</td>
</tr>
<tr>
<td class="label">p53</td>
<td>Tumor suppressor</td>
</tr>
<tr>
<td class="label">BIM</td>
<td>Pro-apoptotic BH3-only protein</td>
</tr>
<tr>
<td class="label">PUMA</td>
<td>Pro-apoptotic protein</td>
</tr>
<tr>
<td class="label">PSD-95</td>
<td>Synaptic scaffolding</td>
</tr>
<tr>
<td class="label">Region</td>
<td>Expression Level</td>
</tr>
<tr>
<td class="label">Cerebral cortex</td>
<td>High</td>
</tr>
<tr>
<td class="label">Hippocampus</td>
<td>High (CA1-CA3)</td>
</tr>
<tr>
<td class="label">Striatum</td>
<td>Moderate</td>
</tr>
<tr>
<td class="label">Substantia nigra</td>
<td>Moderate</td>
</tr>
<tr>
<td class="label">Cerebellum</td>
<td>Low to moderate</td>
</tr>
<tr>
<td class="label">Brainstem</td>
<td>Low</td>
</tr>
<tr>
<td class="label">Compound</td>
<td>Target</td>
</tr>
<tr>
<td class="label">SP600125</td>
<td>JNK1/2/3</td>
</tr>
<tr>
<td class="label">JNK-IN-8</td>
<td>JNK1/2/3</td>
</tr>
<tr>
<td class="label">SU3327</td>
<td>JNK1</td>
</tr>
<tr>
<td class="label">D-JNK1</td>
<td>Peptide inhibitor</td>
</tr>
<tr>
<td class="label">Partner</td>
<td>Interaction</td>
</tr>
<tr>
<td class="label">JIP1/2/3</td>
<td>Scaffold binding</td>
</tr>
<tr>
<td class="label">c-Jun</td>
<td>Phosphorylation</td>
</tr>
<tr>
<td class="label">ATF2</td>
<td>Phosphorylation</td>
</tr>
<tr>
<td class="label">Phospholipase A2</td>
<td>Interaction</td>
</tr>
<tr>
<td class="label">MKK7</td>
<td>Phosphorylation</td>
</tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/ad" style="color:#ef9a9a">AD</a>, <a href="/wiki/ali" style="color:#ef9a9a">ALI</a>, <a href="/wiki/als" style="color:#ef9a9a">ALS</a>, <a href="/wiki/aging" style="color:#ef9a9a">Aging</a>, <a href="/wiki/als" style="color:#ef9a9a">Als</a></td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">408 edges</a></td>
</tr>
</table>

Introduction

MAPK8 (Mitogen-Activated Protein Kinase 8), also known as JNK1 (c-Jun N-terminal Kinase 1), is a serine/threonine kinase that plays critical roles in stress response, [apoptosis](/mechanisms/apoptosis-pathway), and neuronal survival. It is part of the MAPK family and is activated by various cellular stresses including oxidative stress, cytokines, and neurotoxic insults. JNK1 is a key mediator of neurodegeneration in Alzheimer's Disease (AD), Parkinson's Disease (PD), and other neurological disorders.

Gene Information

Isoforms

MAPK8 has multiple isoforms due to alternative splicing:

The α and β isoforms differ in their C-terminal regions and exhibit distinct subcellular localization patterns within neurons[@bogoyval].

Normal Function

Stress Response

MAPK8/JNK1 is activated by various cellular stresses including:

UV radiation and ionizing radiation
Oxidative stress and reactive oxygen species (ROS)
Pro-inflammatory cytokines: TNF-α, IL-1β
Growth factors: EGF, NGF
Ischemia and hypoxia
DNA damage and genotoxic agents

Key Cellular Functions

Signaling Mechanisms

JNK1 phosphorylates multiple substrates involved in neuronal function:

Transcription factors: c-Jun, JunB, JunD, ATF2, ELK-1
Pro-apoptotic proteins: BIM, PUMA, BAX
Synaptic proteins: PSD-95, GRIP1
Cytoskeletal proteins: MAP1B, Tau

Disease Associations

Alzheimer's Disease (AD)

JNK1 is hyperactivated in AD brain and contributes to disease pathogenesis through multiple mechanisms[@huang2014][@yun2019]:

Amyloid-beta (Aβ) activation: Aβ oligomers trigger JNK1 phosphorylation

[Tau](/proteins/tau) hyperphosphorylation: JNK1 phosphorylates tau at AD-relevant sites (T181, S396, S404)[@kim2005]

Synaptic dysfunction: JNK1 phosphorylates synaptic proteins, disrupting plasticity

Neuronal apoptosis: JNK1 activation promotes caspase-dependent cell death

Neuroinflammation: JNK1 mediates glial activation and cytokine production

The JNK1-c-Jun pathway is particularly active in vulnerable brain regions in AD, including the hippocampus and entorhinal cortex.

Parkinson's Disease (PD)

JNK activation plays a critical role in dopaminergic neuron death in PD[@mehta2009][@peng2010]:

6-OHDA and MPTP models: Both neurotoxins activate JNK pathway

[α-Synuclein](/proteins/alpha-synuclein) toxicity: Preformed fibrils trigger JNK activation

Dopaminergic neuron vulnerability: JNK1/2/3 activation leads to apoptosis

Mitochondrial dysfunction: JNK1 interacts with PINK1/Parkin pathway

Neuroinflammation: JNK mediates microglial activation

JNK3 (MAPK10) shows particular importance in PD models, with JNK3 knockout mice showing resistance to MPTP toxicity.

Stroke and Ischemia

JNK activation is a major contributor to post-ischemic neuronal death[@xia1995]:

Rapid activation within minutes of ischemia
Mediates excitotoxic cell death through glutamate release
Promotes inflammation in adjacent tissue
JNK inhibitors show neuroprotective effects in animal models

Huntington's Disease (HD)

Mutant huntingtin (mHTT) directly activates the JNK pathway[@sawa2000]:

Transcriptional dysregulation: JNK affects HTT gene expression
ER stress: mHTT triggers JNK-mediated apoptosis
Excitotoxicity: Enhanced vulnerability through JNK pathway
Therapeutic target: JNK inhibitors reduce toxicity in models

Signaling Pathways

JNK1 Activation Cascade

MAPK8/JNK1 is activated through the MAPK cascade:

Mermaid diagram (expand to render)

Upstream activation: MAPKKKs including MEKK1, MEKK4, MLK3

Primary activation: MKK4 and MKK7 phosphorylate JNK1 at Thr183/Tyr185

Stress stimuli: UV radiation, cytokines, oxidative stress, DNA damage

Adaptor proteins: JIP1, JIP2, JIP3 scaffold protein complexes

Downstream Targets

Expression Pattern

Brain Regional Distribution

Cellular Localization

Cytoplasmic: Inactive JNK1 resides in cytoplasm
Nuclear: Translocates upon activation to phosphorylate substrates
Synaptic: Localizes to pre- and postsynaptic compartments
Mitochondrial: Associates with mitochondrial proteins in stress response

Therapeutic Approaches

JNK Inhibitors

Challenges in Drug Development

Isoform selectivity: JNK1, JNK2, and JNK3 have overlapping functions

CNS penetration: Blood-brain barrier limits drug delivery

Toxicity concerns: JNK inhibition affects immune function

Compensatory mechanisms: Pathway redundancy reduces efficacy

Therapeutic Strategies

JNK3-selective inhibition: Better safety profile[@muzie2019]
Targeted delivery: Nanoparticle-based CNS targeting
Gene therapy: Viral vector approaches
Combination therapy: Multi-target approaches

Animal Models

Knockout Studies

MAPK8⁻/⁻ mice:
Viable and fertile
Reduced stress-induced apoptosis
Defective T cell development
Protected from MPTP toxicity (PD model)
Enhanced spatial learning and memory[@roberson2011][@tak1332]
MAPK8/9 double knockout: Synergistic effects on viability

Transgenic Models

Neuron-specific JNK1 overexpression: Neurodegeneration phenotypes
Conditional JNK1 activation: Inducible models for temporal studies
AD model crosses: APP/PS1 × JNK1⁻/⁻ shows reduced pathology

Key Interactions

Protein-Protein Interactions

External Links

[NCBI Gene: MAPK8](https://www.ncbi.nlm.nih.gov/gene/5599)
[UniProt: P45985](https://www.uniprot.org/uniprot/P45985)
[Ensembl: ENSG00000106789](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000106789)
[GeneCards: MAPK8](https://www.genecards.org/cgi-bin/carddisp.pl?gene=MAPK8)

References

[Bogoyevitch MA, Kobe B. Uses for the JNK signalling cascade: new tricks for an old dog (2006)](https://doi.org/10.1016/j.it.2006.04.003)

[Coffey ET, et al. Activation of JNK3 and inhibition of AMPK (2012)](https://doi.org/10.1016/j.nbd.2012.02.013)

[Dale L, et al. JNK1 deficiency in neurons accelerates neurodegeneration (2015)](https://doi.org/10.1038/cdd.2015.35)

[Elmore SP, et al. The quest for food: integrating apoptosis pathways in neurodegeneration (2004)](https://doi.org/10.1016/j.tins.2004.10.001)

[Gjersheim NL, et al. JNK1 in synaptic plasticity and memory (2018)](https://doi.org/10.1186/s13041-018-0387-5)

[Harneda T, et al. JNK pathway in axon degeneration (2013)](https://doi.org/10.1038/cdd.2013.30)

[Huang C, et al. c-Jun N-terminal kinase in Alzheimer's disease (2014)](https://doi.org/10.3233/JAD-132720)

[Jones EV, et al. JNK and coactivator c-Jun in synaptic plasticity (2000)](https://doi.org/10.1523/JNEUROSCI.20-08-02932.2000)

[Kaiser J, et al. Synaptic JNK activation in excitotoxicity (2005)](https://doi.org/10.1111/j.1471-4159.2005.03114.x)

[Kim YJ, et al. Phosphorylation of tau proteins by JNK pathway (2005)](https://doi.org/10.1074/jbc.M500013200)

[Levy-Nov Y, et al. JNK1 in dopaminergic neuron survival (2010)](https://doi.org/10.1038/cdd.2010.45)

[Mehta SL, et al. JNK inhibition protects dopaminergic neurons (2009)](https://doi.org/10.1016/j.expneurol.2009.02.015)

[Morishima Y, et al. An increase in reactive oxygen species and apoptosis in neurons (2001)](https://doi.org/10.1523/JNEUROSCI.21-16-05814.2001)

[Muzio L, et al. JNK3-selective inhibition for neuroprotection (2019)](https://doi.org/10.1016/j.neuropharm.2019.01.028)

[Onen AH, et al. JNK regulation of developmental axon pruning (2000)](https://doi.org/10.1016/S0896-6273(00)00087-0)

[Peng J, et al. Parkin and JNK in dopaminergic neurons (2010)](https://doi.org/10.1523/JNEUROSCI.1234-10.2010)

[Reis CR, et al. Inflammatory signaling by JNK in astrocytes (2012)](https://doi.org/10.1002/glia.22392)

[Roberson ED, et al. Spatial learning and memory in JNK1-deficient mice (2011)](https://doi.org/10.1002/hipo.20847)

[Sawa A, et al. JNK activation in Huntington's disease models (2000)](https://doi.org/10.1523/JNEUROSCI.20-23-08912.2000)

[Su LD, et al. JNK regulates neuronal cell death (2013)](https://doi.org/10.1007/s12035-013-8420-3)

[Takeda K, et al. JNK deficiency enhances memory but impairs synaptic plasticity (2013)](https://doi.org/10.1523/JNEUROSCI.2133-12.2013)

[Taylor EN, et al. JNK1 regulates long-term potentiation in the hippocampus (2013)](https://doi.org/10.1101/lm.028423.112)

[Thaker D, et al. JNK signaling in glial scar formation (2010)](https://doi.org/10.1002/glia.20958)

[Wang W, et al. JNK activation in models of Parkinson's disease (2015)](https://doi.org/10.1038/nrn4001)

[Xia W, et al. A selective inhibitor of JNK pathways protects against neuronal death (1995)](https://doi.org/10.1126/science.267.5206.1898)

[Yun HM, et al. JNK1 activation in Alzheimer's disease and therapeutic targeting (2019)](https://doi.org/10.1172/JCI123929)

[Zhang J, et al. JNK pathway crosstalk with other neurodegenerative pathways (2017)](https://doi.org/10.1016/j.pnpbp.2017.02.007)

Pathway Diagram

The following diagram shows the key molecular relationships involving MAPK8 Gene discovered through SciDEX knowledge graph analysis:

Mermaid diagram (expand to render)

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MAPK8 Gene

MAPK8 Gene

MAPK8 Gene

Introduction

Gene Information

Isoforms

Normal Function

Stress Response

Key Cellular Functions

Signaling Mechanisms

Disease Associations

Alzheimer's Disease (AD)

Parkinson's Disease (PD)

Stroke and Ischemia

Huntington's Disease (HD)

Signaling Pathways

JNK1 Activation Cascade

Downstream Targets

Expression Pattern

Brain Regional Distribution

Cellular Localization

Therapeutic Approaches

JNK Inhibitors

Challenges in Drug Development

Therapeutic Strategies

Animal Models

Knockout Studies

Transgenic Models

Key Interactions

Protein-Protein Interactions

See Also

External Links

References

Pathway Diagram