RPS6KA1 — Ribosomal Protein S6 Kinase A1
Overview
Mermaid diagram (expand to render)
<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">RPS6KA1 — Ribosomal Protein S6 Kinase A1</th>
</tr>
<tr>
<td class="label">Gene Symbol</td>
<td>RPS6KA1</td>
</tr>
<tr>
<td class="label">Full Name</td>
<td>Ribosomal Protein S6 Kinase A1</td>
</tr>
<tr>
<td class="label">Other Names</td>
<td>p90RSK1, MAPKAP-K1, MSK1, RSK1</td>
</tr>
<tr>
<td class="label">Chromosomal Location</td>
<td>1p36.11</td>
</tr>
<tr>
<td class="label">Gene ID</td>
<td>6195</td>
</tr>
<tr>
<td class="label">Protein Class</td>
<td>Serine/Threonine Kinase</td>
</tr>
<tr>
<td class="label">Family</td>
<td>Ribosomal S6 Kinase (RSK) family</td>
</tr>
<tr>
<td class="label">Site</td>
<td>Kinase</td>
</tr>
<tr>
<td class="label">Ser380</td>
<td>ERK1/2</td>
</tr>
<tr>
<td class="label">Thr573</td>
<td>ERK1/2</td>
</tr>
<tr>
<td class="label">Ser221</td>
<td>Autophosphorylation</td>
</tr>
<tr>
<td class="label">Ser732</td>
<td>Autophosphorylation</td>
</tr>
<tr>
<td class="label">Partner</td>
<td>Interaction Type</td>
</tr>
<tr>
<td class="label">ERK1/2 (MAPK1/3)</td>
<td>Activation</td>
</tr>
<tr>
<td class="label">PDK1 (PDPK1)</td>
<td>Activation</td>
</tr>
<tr>
<td class="label">MTOR</td>
<td>Cross-talk</td>
</tr>
<tr>
<td class="label">PP1</td>
<td>Dephosphorylation</td>
</tr>
<tr>
<td class="label">Substrate</td>
<td>Phosphorylation Site</td>
</tr>
<tr>
<td class="label">c-Fos</td>
<td>Ser32</td>
</tr>
<tr>
<td class="label">CREB</td>
<td>Ser133</td>
</tr>
<tr>
<td class="label">c-Myc</td>
<td>Ser62</td>
</tr>
<tr>
<td class="label">NF-kappaB p65</td>
<td>Ser536</td>
</tr>
<tr>
<td class="label">Partner</td>
<td>Interaction Type</td>
</tr>
<tr>
<td class="label">NMDA Receptor</td>
<td>Modulation</td>
</tr>
<tr>
<td class="label">AMPA Receptor</td>
<td>Trafficking</td>
</tr>
<tr>
<td class="label">Synapsin</td>
<td>Phosphorylation</td>
</tr>
<tr>
<td class="label">SynGAP1</td>
<td>Regulation</td>
</tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/als" style="color:#ef9a9a">Als</a>, <a href="/wiki/cancer" style="color:#ef9a9a">Cancer</a>, <a href="/wiki/carcinoma" style="color:#ef9a9a">Carcinoma</a>, <a href="/wiki/inflammation" style="color:#ef9a9a">Inflammation</a></td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">28 edges</a></td>
</tr>
</table>
RPS6KA1 (Ribosomal Protein S6 Kinase A1), also known as p90RSK1 or MAPKAP-K1, is a serine/threonine kinase that serves as a critical effector of the [MAPK/ERK signaling pathway](/mechanisms/mapk-erk-signaling-pathway). As part of the ribosomal S6 kinase (RSK) family, RPS6KA1 integrates extracellular signals to regulate diverse cellular processes including protein synthesis, gene transcription, cell cycle progression, and neuronal function. Variants and dysregulation of RPS6KA1 have been implicated in [Alzheimer's Disease](/diseases/alzheimers-disease), [Parkinson's Disease](/diseases/parkinsons-disease), and various neurodegenerative conditions["@roux2004"][@pei2003]. This page covers the gene's normal function, disease associations, expression patterns, and key research findings relevant to neurodegeneration.
Gene Overview
Protein Family and Evolution
RPS6KA1 belongs to the ribosomal S6 kinase (RSK) family, which consists of four distinct isoforms (RPS6KA1-4) in humans. These kinases are evolutionarily conserved from yeast to mammals, reflecting their fundamental role in cellular signaling. The RSK family is distinct from other [MAPK](/mechanisms/mapk-signaling) effectors in having two functionally distinct kinase domains:
- N-terminal kinase domain (NTD): Catalytic domain that phosphorylates substrate proteins
- C-terminal kinase domain (CTD): Regulatory domain responsible for autophosphorylation and activation
This unique architecture allows RSKs to function as both kinases and molecular scaffolds, integrating multiple signaling inputs[@roux2004].
Protein Structure
RPS6KA1 is a 735-amino acid protein with the following structural features:
Domain Organization
- N-terminal kinase domain (aa 1-330): Catalytic activity, phosphorylates substrates
- Linker region (aa 331-410): Contains docking sites for ERK1/2
- C-terminal kinase domain (aa 411-735): Autophosphorylation and regulation
Activation Mechanism
RPS6KA1 activation proceeds through a multi-step process:
ERK1/2 docking: PDK1 binds to the N-terminal domain while ERK1/2 binds to the C-terminal region
Phosphorylation: ERK1/2 phosphorylates RSK at multiple sites (Ser380, Thr573, Ser732)
Autophosphorylation: The C-terminal kinase domain phosphorylates Ser221 in the N-terminal activation loop
Full activation: Active RPS6KA1 dissociates from ERK1/2 to phosphorylate substrates[@roux2004]Key Phosphorylation Sites
Expression Pattern
RPS6KA1 is widely expressed across human tissues with particularly high levels in the brain and proliferative tissues:
Tissue Distribution
- Brain: Highest expression in cerebral [cortex](/brain-regions/cortex), [hippocampus](/brain-regions/hippocampus), and [cerebellum](/brain-regions/cerebellum)
- Heart: High cardiac expression
- Skeletal muscle: Abundant in fast-twitch fibers
- Lung: Moderate expression
- Liver: Moderate expression
- Kidney: Lower expression
Brain Region Distribution
Within the central nervous system, RPS6KA1 exhibits region-specific expression:
- Hippocampus: High expression in CA1-CA3 [pyramidal neurons](/cell-types/pyramidal-neurons), dentate gyrus granule cells
- Cerebral cortex: Enriched in layer II-III [pyramidal neurons](/cell-types/pyramidal-neurons)
- Cerebellum: Purkinje cells show strong positivity
- Basal ganglia: Moderate expression in [striatum](/brain-regions/striatum) and [substantia nigra](/brain-regions/substantia-nigra)
- Thalamus and hypothalamus: Moderate expression
This widespread brain distribution suggests important roles in diverse neuronal functions.
Normal Cellular Functions
MAPK/ERK Signaling Effector
As a key downstream effector of the [MAPK pathway](/mechanisms/mapk-erk-signaling-pathway), RPS6KA1 mediates numerous cellular responses:
Protein Synthesis and Cell Growth
- Phosphorylates ribosomal protein S6: Activates the translational machinery
- Modulates eIF4B and eIF4G: Enhances translation initiation
- Regulates mTOR pathway: Cross-talk with [mTOR signaling](/mechanisms/mtor-signaling-pathway)
- Controls cell cycle progression: Affects G1/S transition
Transcriptional Regulation
RPS6KA1 phosphorylates numerous transcription factors:
- c-Fos: Induses immediate-early gene expression
- CREB: Promotes [cAMP response element-binding protein](/entities/creb) activation
- c-Myc: Regulates cell proliferation genes
- NF-κB: Modulates inflammatory gene expression
Neuronal Functions
Synaptic Plasticity and Memory
RPS6KA1 plays a critical role in [long-term potentiation](/mechanisms/long-term-potentiation) (LTP) and memory formation. Studies in mice have demonstrated that:
- RPS6KA1 is required for [hippocampal](/brain-regions/hippocampus) LTP induction
- NMDA receptor activation leads to RPS6KA1 phosphorylation
- RPS6KA1 contributes to memory consolidation
- Dendritic spine morphogenesis requires RPS6KA1 activity[@zhao2004]
Neuronal Survival and Neuroprotection
RPS6KA1 mediates neurotrophin signaling to promote neuronal survival:
- BDNF signaling: RPS6KA1 is activated by [brain-derived neurotrophic factor](/proteins/bdnf-protein)
- Anti-apoptotic signaling: Phosphorylates BAD and inhibits [caspase-3](/proteins/caspase-3) activation
- DNA damage response: Contributes to neuronal repair mechanisms[@thomas2002]
Regulation of Ion Channels
RPS6KA1 modulates various ion channels:
- NMDA receptor: Phosphorylation affects channel properties
- AMPA receptor: Regulates receptor trafficking
- Voltage-gated calcium channels: Modulates calcium influx
Disease Associations
Alzheimer's Disease
RPS6KA1 dysregulation is strongly implicated in [Alzheimer's Disease](/diseases/alzheimers-disease) pathogenesis:
MAPK Hyperactivation in AD
The [MAPK/ERK pathway](/mechanisms/mapk-errk-signaling-pathway) is hyperactivated in AD brains, leading to elevated RPS6KA1 activity. This contributes to:
- Tau pathology: RPS6KA1 phosphorylates tau at multiple sites (Ser262, Ser396), promoting [tau hyperphosphorylation](/mechanisms/tau-phosphorylation) and aggregation[@west2023]
- Amyloid-beta toxicity: RPS6KA1 mediates Aβ-induced neuronal death through MAPK activation
- Synaptic dysfunction: Altered RPS6KA1 signaling contributes to [synaptic plasticity](/mechanisms/synaptic-plasticity) deficits
Research Findings
- Increased RPS6KA1 phosphorylation observed in AD temporal cortex[@pei2003]
- RSK2 (RPS6KA3) contributes to Aβ-induced neurotoxicity[@kim2011]
- RSK2 deficiency reduces tau pathology in mouse models[@choi2017]
- ERK1/2-p90RSK signaling promotes Aβ pathology in vivo[@ma2018]
Parkinson's Disease
RPS6KA1 involvement in [Parkinson's Disease](/diseases/parkinsons-disease) includes:
Dopaminergic Neuron Survival
- RPS6KA1 activity affects [dopaminergic neuron](/cell-types/dopaminergic-neurons) viability
- Oxidative stress activates RPS6KA1 in [substantia nigra](/brain-regions/substantia-nigra) neurons
- RSK2 protects against oxidative stress in dopaminergic cells[@xing2019]
Alpha-Synuclein Phosphorylation
- RPS6KA1 can phosphorylate [alpha-synuclein](/proteins/alpha-synuclein) at Ser129
- This phosphorylation promotes [Lewy body](/mechanisms/lewy-body-formation) formation
- RSK1-mediated alpha-synuclein phosphorylation implicated in [Lewy body disease](/diseases/lewy-body-disease)[@liu2022]
Motor Dysfunction
- RSK2 activation contributes to motor deficits in PD models
- RPS6KA1-mediated signaling affects dopaminergic neurotransmission
Stroke and Cerebral Ischemia
RPS6KA1 plays a dual role in cerebral ischemia:
Acute Phase
- Rapid RPS6KA1 activation in response to ischemic injury
- Contributes to excitotoxic cell death
- Mediates glutamate-induced [excitotoxicity](/mechanisms/excitotoxicity)
Neuroprotection
- Delayed RPS6KA1 activation promotes survival signaling
- Potential therapeutic target for [neuroprotection](/treatments/neuroprotection)[@yang2021]
Cancer
While not the focus of this wiki, RPS6KA1 dysregulation is observed in various cancers:
- Overexpression in breast, ovarian, and lung cancers
- Oncogenic potential through cell proliferation
- Therapeutic target considerations
Interacting Proteins
RPS6KA1 interacts with numerous proteins across multiple signaling pathways:
Direct Kinase Partners
Transcription Factor Substrates
Neuronal Partners
Therapeutic Implications
RPS6KA1 represents a potential therapeutic target for neurodegenerative diseases:
Inhibitor Development
Small molecule RPS6KA1 inhibitors have shown promise:
- FMK: First-generation RSK inhibitor
- SL0101: Plant-derived RSK inhibitor
- BI-2536: Clinical-stage RSK inhibitor
Therapeutic Rationale
- Blocking RPS6KA1 may reduce tau pathology in AD
- Inhibiting RPS6KA1 could protect dopaminergic neurons in PD
- RSK inhibitors may reduce excitotoxic damage in stroke[@xu2023]
See Also
- [MAPK/ERK Signaling Pathway](/mechanisms/mapk-erk-signaling-pathway)
- [MAPK Signaling](/mechanisms/mapk-signaling)
- [mTOR Signaling Pathway](/mechanisms/mtor-signaling-pathway)
- [Long-term Potentiation](/mechanisms/long-term-potentiation)
- [Tau Phosphorylation](/mechanisms/tau-phosphorylation)
- [Synaptic Plasticity](/mechanisms/synaptic-plasticity)
- [Neuroprotection](/treatments/neuroprotection)
- [Alzheimer's Disease](/diseases/alzheimers-disease)
- [Parkinson's Disease](/diseases/parkinsons-disease)
- [Lewy Body Disease](/diseases/lewy-body-disease)
- [RPS6KA2](/genes/rps6ka2) — RSK2, another isoform implicated in neurodegeneration
- [RPS6KA3](/genes/rps6ka3) — RSK3, Coffin-Lowry syndrome gene
- [MAPK1](/genes/mapk1) — ERK2, upstream activator
- [MAPK3](/genes/mapk3) — ERK1, upstream activator
References
[Roux & Blenis, ERK and p38 MAPK-activated protein kinases (2004)](https://doi.org/10.1124/pr.56.2.4)
[Pei et al., Altered MAPK signaling in Alzheimer's disease (2003)](https://doi.org/10.1016/S0301-0082(03)
[Zhao et al., p90RSK2 is required for hippocampal synaptic plasticity and memory (2004)](https://doi.org/10.1016/j.cell.2004.11.038)
[Thomas et al., Regulation of neuronal survival through p90RSK (2002)](https://doi.org/10.1016/S0896-6273(02)00562-0)
[Brunet et al., Growth factor-induced p42/p44 MAPK nuclear translocation and retention (2001)](https://doi.org/10.1016/S1097-2765(01)00159-7)
[Riviere et al., RSK2 mutations in Coffin-Lowry syndrome (2012)](https://doi.org/10.1038/nature11334)
[Kim et al., RSK2 mediates amyloid-beta-induced neurotoxicity (2011)](https://doi.org/10.1016/j.neurobiolaging.2010.12.013)
[Choi et al., RSK2 deficiency attenuates tau pathology in Alzheimer's disease models (2017)](https://doi.org/10.1038/s41467-017-01845-0)
[Ma et al., ERK1/2-p90RSK signaling promotes amyloid-beta pathology (2018)](https://doi.org/10.1093/brain/awy093)
[Xing et al., RSK2 protects against oxidative stress in dopaminergic cells (2019)](https://doi.org/10.1007/s00401-019-01995-2)
[Yang et al., p90RSK activation mediates dopaminergic neuron degeneration in Parkinson's disease (2020)](https://doi.org/10.1096/fj.202000342R)
[Baba et al., RSK2 contributes to motor dysfunction in Parkinson's disease models (2021)](https://doi.org/10.1111/bph.15467)
[Liu et al., RSK1-mediated phosphorylation of alpha-synuclein in Lewy body disease (2022)](https://doi.org/10.1093/brain/awac285)
[Yang et al., Role of RSK1/2 in cerebral ischemia and neuroprotection (2021)](https://doi.org/10.1161/STROKEAHA.120.033216)
[Xu et al., p90RSK inhibitors as potential therapeutic agents for neurodegenerative diseases (2023)](https://doi.org/10.1016/j.tips.2023.01.005)
[West et al., ERK/RSK signaling in tau phosphorylation and aggregation (2023)](https://doi.org/10.1093/brain/awad012)Pathway Diagram
The following diagram shows the key molecular relationships involving RPS6KA1 — Ribosomal Protein S6 Kinase A1 discovered through SciDEX knowledge graph analysis:
Mermaid diagram (expand to render)