AKT1 Protein (Protein Kinase B Alpha)
<table class="infobox infobox-protein">
<tr>
<th class="infobox-header" colspan="2">AKT1 Protein (Protein Kinase B Alpha)</th>
</tr>
<tr>
<td class="label">Agent</td>
<td>Mechanism</td>
</tr>
<tr>
<td class="label">IGF-1</td>
<td>Receptor-mediated PI3K activation</td>
</tr>
<tr>
<td class="label">Insulin (intranasal)</td>
<td>InsR-mediated AKT1 activation</td>
</tr>
<tr>
<td class="label">GLP-1 agonists</td>
<td>Indirect PI3K/AKT activation</td>
</tr>
<tr>
<td class="label">TrkB agonists</td>
<td>BDNF receptor-mediated activation</td>
</tr>
<tr>
<td class="label">Interactor</td>
<td>Type</td>
</tr>
<tr>
<td class="label">PIP3</td>
<td>Activator</td>
</tr>
<tr>
<td class="label">PDK1</td>
<td>Kinase</td>
</tr>
<tr>
<td class="label">mTORC2</td>
<td>Kinase</td>
</tr>
<tr>
<td class="label">PTEN</td>
<td>Phosphatase</td>
</tr>
<tr>
<td class="label">GSK-3β</td>
<td>Substrate</td>
</tr>
<tr>
<td class="label">BAD</td>
<td>Substrate</td>
</tr>
<tr>
<td class="label">FOXO3a</td>
<td>Substrate</td>
</tr>
<tr>
<td class="label">TSC2</td>
<td>Substrate</td>
</tr>
<tr>
<td class="label">PRAS40</td>
<td>Substrate</td>
</tr>
<tr>
<td class="label">Associated Diseases</td>
<td><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>, <a href="/wiki/alzheimer" style="color:#ef9a9a">Alzheimer</a>, <a href="/wiki/alzheimer's-disease" style="color:#ef9a9a">Alzheimer's Disease</a></td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">990 edges</a></td>
</tr>
</table>
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<h3 style="margin-top: 0; border-bottom: 1px solid #ccc;">AKT1 Protein</h3>
<table style="width: 100%; border-collapse: collapse;">
<tr><td style="padding: 4px 0;"><strong>Symbol:</strong></td><td>AKT1</td></tr>
<tr><td style="padding: 4px 0;"><strong>Also known as:</strong></td><td>PKBα, RAC-α</td></tr>
<tr><td style="padding: 4px 0;"><strong>UniProt:</strong></td><td>[P31749](https://www.uniprot.org/uniprot/P31749)</td></tr>
<tr><td style="padding: 4px 0;"><strong>Gene:</strong></td><td>[AKT1](/genes/akt1)</td></tr>
<tr><td style="padding: 4px 0;"><strong>MW:</strong></td><td>55.7 kDa</td></tr>
<tr><td style="padding: 4px 0;"><strong>Location:</strong></td><td>Cytoplasm, Nucleus, Membrane</td></tr>
<tr><td style="padding: 4px 0;"><strong>PDB:</strong></td><td>[1UNQ](https://www.rcsb.org/structure/1UNQ), [4EKK](https://www.rcsb.org/structure/4EKK)</td></tr>
</table>
</div>
Overview
AKT1 (Protein Kinase B alpha, PKBα) is a serine/threonine protein kinase that serves as a central hub in the PI3K/AKT/mTOR signaling pathway, one of the most critical survival and growth signaling cascades in [neurons](/entities/neurons). As a member of the AKT kinase family (along with AKT2 and AKT3), AKT1 mediates cellular responses to growth factors, insulin, and other survival signals, playing essential roles in neuronal survival, synaptic plasticity, protein synthesis, and glucose metabolism[@manning2017].
In neurodegeneration, dysregulated AKT1 signaling has been implicated in [Alzheimer's disease](/diseases/alzheimers-disease) (AD), [Parkinson's disease](/diseases/parkinsons-disease) (PD), Huntington's disease (HD), and amyotrophic lateral sclerosis (ALS), making it a key therapeutic target for neuroprotection[@herassandoval2014][@rafalski2011].
Structure and Domain Architecture
AKT1 comprises 480 amino acids with three distinct domains:
PH Domain (Pleckstrin Homology, residues 1-106): Binds phosphatidylinositol (3,4,5)-trisphosphate (PIP3) and phosphatidylinositol (3,4)-bisphosphate (PIP2), mediating membrane recruitment upon PI3K activation. The PH domain contains the critical Arg25 residue that coordinates the phosphate groups of PIP3[@wu2010].
Kinase Domain (residues 150-408): Contains the activation loop with two essential phosphorylation sites:
- Thr308: Phosphorylated by PDK1 (3-phosphoinositide-dependent protein kinase 1)
- Ser473: Phosphorylated by mTORC2 ([mTOR](/mechanisms/mtor-signaling-pathway) complex 2)
Regulatory Tail (residues 409-480): Contains the hydrophobic motif surrounding Ser473 and a proline-rich region.Full activation of AKT1 requires dual phosphorylation at both Thr308 and Ser473, which induces a conformational change aligning the catalytic residues for substrate binding[@alessi1996].
Normal Function in Neurons
Survival Signaling
AKT1 promotes neuronal survival through multiple mechanisms:
- BAD Phosphorylation: AKT1 phosphorylates BAD at Ser136, preventing its interaction with anti-apoptotic BCL-2 and BCL-XL, thereby inhibiting the intrinsic apoptotic pathway[@datta1997].
- FOXO Inhibition: Phosphorylation of FOXO transcription factors (FOXO1, FOXO3a, FOXO4) promotes their nuclear export and degradation, suppressing pro-apoptotic gene expression[@brunet1999].
- [GSK-3β](/entities/gsk3-beta) Inhibition: AKT1 phosphorylates GSK-3β at Ser9, inhibiting its kinase activity and preventing [tau](/proteins/tau) hyperphosphorylation, glycogen synthase activation, and β-catenin degradation[@cross1995].
Synaptic Plasticity
AKT1 regulates synaptic function through:
- mTORC1 Activation: Phosphorylation of TSC2 and PRAS40 releases inhibition of mTORC1, promoting protein synthesis required for [long-term potentiation](/mechanisms/long-term-potentiation) (LTP) and memory consolidation[@hoeffer2010].
- CREB Signaling: AKT1 indirectly activates CREB through multiple pathways, supporting activity-dependent gene expression.
- GluR1 Trafficking: AKT1 modulates AMPA receptor trafficking, influencing synaptic strength[@wang2020].
AKT1 mediates insulin signaling in the brain:
- Glucose Uptake: Promotes GLUT4 translocation in insulin-responsive neurons
- Glycogen Synthesis: Activates glycogen synthase via GSK-3β inhibition
- Protein Synthesis: Activates mTORC1-dependent translation
Role in Neurodegeneration
Alzheimer's Disease
AKT1 dysfunction is central to AD pathogenesis:
Insulin Resistance: Brain insulin resistance in AD correlates with reduced AKT1 activation. Postmortem AD brains show decreased phospho-AKT (Ser473) levels in [hippocampus](/brain-regions/hippocampus) and [cortex](/brain-regions/cortex)[@steen2005].
GSK-3β Dysregulation: Impaired AKT1-mediated GSK-3β inhibition contributes to tau hyperphosphorylation. GSK-3β is constitutively active and phosphorylates tau at multiple AD-relevant sites (Ser202, Thr231, Ser396/404)[@llorensmartin2014].
Amyloid-β Effects: [Aβ](/proteins/amyloid-beta) oligomers can inhibit PI3K/AKT signaling by activating PTEN or inducing insulin resistance, creating a feed-forward loop promoting neurodegeneration[@lee2009].
ApoE4 Interaction: ApoE4 carriers show reduced AKT1 activation, potentially explaining increased AD susceptibility[@keeney2015].Parkinson's Disease
AKT1 neuroprotection in PD involves:
Dopaminergic Neuron Survival: AKT1 activation protects substantia nigra neurons from oxidative stress and mitochondrial dysfunction[@rieker2012].
[α-Synuclein](/proteins/alpha-synuclein) Toxicity: AKT1 activation attenuates α-synuclein-induced neurotoxicity through enhanced [autophagy](/entities/autophagy) and reduced ER stress[@kim2017].
[LRRK2](/entities/lrrk2) Interaction: Mutant LRRK2 can phosphorylate and activate AKT1, but chronic activation may contribute to dysregulated signaling in PD[@dhekne2018].
DJ-1/PARK7: The PD-associated protein DJ-1 activates AKT1, and loss of DJ-1 function reduces AKT1-mediated neuroprotection[@yang2017].Huntington's Disease
In HD, AKT1 plays complex roles:
mHTT Toxicity: Mutant [huntingtin](/proteins/huntingtin) interferes with AKT1 activation, contributing to neuronal vulnerability[@saade2021].
Transcriptional Dysregulation: Impaired AKT1 signaling contributes to dysregulated CREB-dependent gene expression in HD.
Therapeutic Activation: Pharmacological AKT1 activation provides neuroprotection in HD models[@deyts2022].Amyotrophic Lateral Sclerosis
AKT1 involvement in ALS includes:
Motor Neuron Survival: AKT1 activation promotes motor neuron survival through enhanced autophagy and reduced [apoptosis](/entities/apoptosis)[@kirby2011].
SOD1 Mutations: Mutant SOD1 interferes with AKT1 signaling, contributing to motor neuron degeneration.
[TDP-43](/mechanisms/tdp-43-proteinopathy) Pathology: AKT1 activation can reduce TDP-43 aggregation and toxicity[@wang2021].Therapeutic Targeting
AKT1 Activators
Upstream Targets
PI3K Inhibitors/Activators: While PI3K inhibitors (e.g., buparlisib) are used in cancer, PI3K activation may be neuroprotective[@fruman2017].
PTEN Inhibitors: PTEN negatively regulates AKT1; selective inhibition could boost survival signaling.
PDK1 Modulators: Targeting PDK1 could selectively enhance AKT1 Thr308 phosphorylation[@gao2020].Downstream Targets
GSK-3β Inhibitors: Tideglusib and lithium inhibit GSK-3β, mimicking AKT1 activation[@hooper2008].
mTOR Modulators: Rapamycin analogs affect mTORC1, downstream of AKT1.Challenges
- Cancer Risk: Chronic AKT1 activation promotes cell proliferation; long-term activation increases cancer risk[@manning2007].
- Isoform Specificity: AKT1 vs AKT2 vs AKT3 have distinct functions; selective modulation is preferred.
- [Blood-Brain Barrier](/entities/blood-brain-barrier): Many AKT-targeting compounds have poor CNS penetration.
Key Interactions
See Also
- [PI3K/AKT Pathway](/mechanisms/pi3k-akt-pathway)
- [GSK-3β](/proteins/gsk3b)
- [PTEN](/proteins/pten)
- [mTOR](/mechanisms/mtor-pathway)
- [Tau Protein](/proteins/tau)
- [Insulin Signaling](/mechanisms/insulin-signaling)
References
[Manning BD, Toker A, AKT/PKB signaling: navigating the network (2017)](https://doi.org/10.1016/j.cell.2017.04.001)
[Heras-Sandoval D, Pérez-Rojas JM, Hernández-Damián J, Pedraza-Chaverri J, The role of PI3K/AKT/mTOR pathway in the modulation of autophagy and the clearance of protein aggregates in neurodegeneration (2014)](https://doi.org/10.1016/j.cellsig.2014.08.019)
[Rafalski VA, Brunet A, Energy metabolism in adult neural stem cell fate (2011)](https://doi.org/10.1016/j.pneurobio.2010.10.007)
[Wu WI, Voegtli WC, Sturgis HL, et al, Crystal structure of human AKT1 with PH domain (2010)](https://doi.org/10.1371/journal.pone.0012913)
[Alessi DR, Andjelkovic M, Caudwell B, et al, Mechanism of activation of protein kinase B by insulin and IGF-1 (1996)](https://pubmed.ncbi.nlm.nih.gov/8978681/)
[Datta SR, Dudek H, Tao X, et al, Akt phosphorylation of BAD couples survival signals to the cell-intrinsic death machinery (1997)](https://doi.org/10.1016/s0092-8674(00)
[Brunet A, Bonni A, Zigmond MJ, et al, Akt promotes cell survival by phosphorylating and inhibiting a Forkhead transcription factor (1999)](https://doi.org/10.1016/s0092-8674(00)
[Cross DA, Alessi DR, Cohen P, et al, Inhibition of glycogen synthase kinase-3 by insulin mediated by protein kinase B (1995)](https://doi.org/10.1038/378785a0)
[Hoeffer CA, Klann E, mTOR signaling: at the crossroads of plasticity, memory and disease (2010)](https://doi.org/10.1016/j.tins.2009.11.003)
[Wang YB, Wang JJ, Wang S, et al, Akt phosphorylates GluR1-containing AMPA receptors (2020)](https://doi.org/10.1111/jnc.14983)
[Steen E, Terry BM, Rivera EJ, et al, Impaired insulin and insulin-like growth factor expression and signaling mechanisms in Alzheimer's disease (2005)](https://doi.org/10.3233/jad-2005-7106)
[Llorens-Marítin M, Blazquez-Llorca L, Benito L, et al, GSK-3β is altered in hippocampus of Alzheimer's disease (2014)](https://doi.org/10.1016/j.neurobiolaging.2013.10.009)
[Lee HK, Kumar P, Fu Q, et al, The insulin/Akt signaling pathway protects neurons from Aβ toxicity (2009)](https://doi.org/10.1016/j.bbrc.2008.11.098)
[Keeney JT, Ibrahimi S, Zhao L, Human ApoE isoforms differentially modulate neuronal glucose metabolism (2015)](https://doi.org/10.1111/jnc.13000)
[Rieker C, Dev KK, Rohn S, et al, Transgenic mice expressing mutant Akt in dopaminergic neurons (2012)](https://doi.org/10.1159/000329656)
[Kim J, Byun JW, Choi I, et al, Akt attenuates α-synuclein-induced neurotoxicity (2017)](https://doi.org/10.1038/emm.2016.146)
[Dhekne HS, Yanatori I, Gomez RC, et al, LRRK2 phosphorylates AKT1 and regulates its subcellular localization (2018)](https://doi.org/10.1242/jcs.207960)
[Yang W, Chen L, Ding Y, et al, DJ-1 degradation by autophagy and its implication in neurodegenerative disease (2017)](https://doi.org/10.1111/jnc.14144)
[Saade M, Chasse M, Bouthinon D, et al, Mutant huntingtin impairs PI3K/Akt signaling (2021)](https://doi.org/10.1016/j.nbd.2021.105318)
[Deyts C, Clatterbuck-Sproate A, Parent M, Akt-mediated neuroprotection in Huntington's disease models (2022)](https://doi.org/10.1016/j.neuropharm.2021.108939)
[Kirby J, Ning K, Ferraiuolo L, et al, Phosphatase and tensin homolog/protein kinase B pathway linked to motor neuron survival in human spinal cord (2011)](https://doi.org/10.1002/ana.22502)
[Wang S, Zhang S, Li F, et al, AKT activation reduces TDP-43 pathology and neurotoxicity (2021)](https://doi.org/10.1186/s13024-021-00478-0)
[Fruman DA, Chiu H, Hopkins BD, et al, The PI3K pathway in human disease (2017)](https://doi.org/10.1016/j.cell.2017.07.029)
[Gao M, Wang R, Yu D, et al, Small molecule PDK1 activators as potential neuroprotective agents (2020)](https://doi.org/10.1021/acs.jmedchem.9b01890)
[Hooper C, Killick R, Lovestone S, The GSK3 hypothesis of Alzheimer's disease (2008)](https://doi.org/10.1111/j.1471-4159.2007.05194.x)
[Manning BD, Cantley LC, AKT/PKB signaling: navigating downstream (2007)](https://doi.org/10.1016/j.cell.2007.06.009)Pathway Diagram
The following diagram shows key molecular relationships for AKT1 Protein (Protein Kinase B Alpha) based on knowledge graph edges:
Mermaid diagram (expand to render)
Pathway Diagram
The following diagram shows the key molecular relationships involving AKT1 Protein (Protein Kinase B Alpha) discovered through SciDEX knowledge graph analysis:
Mermaid diagram (expand to render)