PIK3R6 Gene
Introduction <table class="infobox infobox-gene">
PIK3R6 (Phosphoinositide-3-Kinase Regulatory Subunit 6) encodes the p101 regulatory subunit of class I phosphoinositide 3-kinases (PI3Ks). While initially characterized in immune cells, emerging research reveals important functions in neuronal survival, synaptic plasticity, and neurodegenerative disease pathogenesis. [@hawkins2015]
Overview ...
PIK3R6 Gene
Introduction <table class="infobox infobox-gene">
PIK3R6 (Phosphoinositide-3-Kinase Regulatory Subunit 6) encodes the p101 regulatory subunit of class I phosphoinositide 3-kinases (PI3Ks). While initially characterized in immune cells, emerging research reveals important functions in neuronal survival, synaptic plasticity, and neurodegenerative disease pathogenesis. [@hawkins2015]
Overview PIK3R6 is located on chromosome 17p13.1 and encodes the p101 (also known as p84) regulatory subunit of PI3K. The gene is catalogued as NCBI Gene ID 27137 and OMIM 607270. p101 forms heterodimers with PI3K catalytic subunits (p110γ) to create functional PI3K complexes that generate phosphatidylinositol-3,4,5-trisphosphate (PIP3). [@vanhaesebroeck2010]
Protein Structure and Function PIK3R6 encodes the p101 regulatory subunit:
SH2 domains : Two src homology 2 domains for phosphotyrosine bindingiSH2 domain : Inter-SH2 domain for dimerization with catalytic subunitp110γ binding : Forms heterodimer with PI3K catalytic subunit p110γMembrane recruitment : Mediates localization to plasma membraneThe p101/p110γ complex is a class IB PI3K predominantly expressed in leukocytes but also detected in [neurons](/entities/neurons) and glial cells. [@wymann2005]
Normal Physiological Functions
PI3K/Akt signaling : Activate downstream Akt pathway promoting cell survivalCell migration : Regulate cytoskeletal dynamics in response to chemoattractantsInflammatory responses : Mediate immune cell activation and cytokine productionNeuronal survival : Support neuronal viability through Akt-dependent mechanismsSynaptic plasticity : Regulate synaptic vesicle trafficking and plasticity
Expression Pattern PIK3R6 shows cell-type specific expression:
Neurons : Moderate expression in cortical and hippocampal neurons[Microglia](/cell-types/microglia-neuroinflammation) : High expression in activated microglia[Astrocytes](/entities/astrocytes) : Detectable expression in astrocytesOligodendrocytes : Low expression in oligodendrocyte lineage cellsImmune cells : Highest expression in macrophages and neutrophilsExpression data is available from the Allen Human Brain Atlas and Brain RNA-seq. [@allen]
Disease Associations
Alzheimer's Disease PI3K/Akt signaling is critically involved in AD pathogenesis:
[Amyloid-beta](/proteins/amyloid-beta) toxicity : PI3K/Akt activation protects neurons from Aβ-induced [apoptosis](/entities/apoptosis)[Tau](/proteins/tau) phosphorylation : Akt regulates tau kinases ([GSK-3β](/entities/gsk3-beta), CDK5) affecting phosphorylationSynaptic dysfunction : PI3K signaling regulates synaptic plasticity and memoryNeuroinflammation : Microglial PI3Kγ contributes to neuroinflammatory responsesTherapeutic potential : PI3K modulators may protect against AD pathologyParkinson's Disease
Dopaminergic neuron survival : PI3K/Akt pathway supports SNc neuron viabilityMitophagy : PI3K signaling regulates mitochondrial quality controlNeuroinflammation : Microglial PI3Kγ promotes neuroinflammation in PDLRRK2 interactions : PIK3R6 may interact with LRRK2 pathogenic variantsTherapeutic targeting : PI3K inhibitors/modulators for PD treatmentAmyotrophic Lateral Sclerosis
Motor neuron survival : PI3K/Akt promotes motor neuron viabilityGlial activation : Astrocytic and microglial PI3K contributes to neuroinflammationAxonal transport : PI3K signaling regulates axonal transport machineryProtein aggregation : PI3K dysregulation affects [autophagy](/entities/autophagy) of protein aggregatesOther Neurological Disorders
Multiple sclerosis : PI3K in immune cell migration across [blood-brain barrier](/entities/blood-brain-barrier)Stroke : PI3K/Akt mediates ischemic preconditioning and neuroprotectionHuntington's disease : PI3K signaling regulates mutant [huntingtin](/proteins/huntingtin) toxicityFrontotemporal dementia : PI3K dysregulation in tauopathiesPsychiatric disorders : PI3K signaling in mood disorders and schizophreniaTherapeutic Implications PI3K signaling pathways represent important therapeutic targets:
PI3K inhibitors : Isoform-selective inhibitors for neuroinflammationAkt activators : Direct Akt activators for neuroprotectionPI3K modulators : Targeting specific cell types (microglia vs. neurons)Combination therapy : PI3K modulators with other disease-modifying approachesRepurposing : FDA-approved PI3K inhibitors for neurodegenerative diseases
Interacting Proteins PIK3R6 interacts with several key proteins:
p110γ (PIK3CG) : Catalytic subunit of class IB PI3KAkt1/PKB : Downstream effector kinaseGSK-3β : Tau kinase regulated by PI3K/Akt[mTOR](/mechanisms/mtor-signaling-pathway) : Downstream regulator of cell growth and autophagyPTEN : Negative regulator of PI3K/Akt signalingSignaling Pathways PIK3R6 participates in critical signaling cascades:
PI3K/Akt/mTOR pathway : Cell survival and growthPI3K/Akt/GSK-3β pathway : Tau phosphorylationPI3K/Akt/NF-κB pathway : Inflammatory gene expressionPI3K/Akt/FOXO pathway : Transcription factor regulationPI3K/Akt/Bad pathway : Apoptosis regulation
Knockout mice : Pik3r6-/- mice show immune cell migration defectsConditional KO mice : Cell-type specific deletion for neuronal studiesPharmacological tools : PI3K inhibitors (wortmannin, LY294002), Akt inhibitorsAAV vectors : For neuronal overexpression or knockdownSummary PIK3R6 encodes the p101 regulatory subunit of class IB PI3K, which plays essential roles in neuronal survival, synaptic plasticity, and neuroinflammation. PI3K/Akt signaling dysfunction contributes to Alzheimer's disease, Parkinson's disease, ALS, and other neurodegenerative disorders. Modulating PIK3R6 and downstream PI3K pathways represents a promising therapeutic strategy for neuroprotection. [@zhang2023]
See Also
[Alzheimer's Disease](/diseases/alzheimers-disease)
[Parkinson's Disease](/diseases/parkinsons-disease)
External Links
[Ensembl: ENSG00000110676](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000110676)
References
[Unknown, Hawkins PT, Stephens LR (2015). PI3K signaling in inflammation and cancer. Biochim Biophys Acta (2015)](https://pubmed.ncbi.nlm.nih.gov/25925676/)
[Vanhaesebroeck B, et al., (2010). PI3K isoforms in cell migration and survival. Nat Rev Cancer (2010)](https://pubmed.ncbi.nlm.nih.gov/20190755/)
[Unknown, Wymann MP, Marone R (2005). PI3K in disease. Curr Opin Cell Biol (2005)](https://pubmed.ncbi.nlm.nih.gov/15821850/)
Unknown, Allen Human Brain Atlas. PIK3R6 expression data (n.d.)
[Zhang L, et al., (2023). PI3K/Akt signaling in Alzheimer's disease. J Alzheimers Dis (2023)](https://pubmed.ncbi.nlm.nih.gov/37249876/)
[Herrero-Martin G, et al., (2018). PIK3R6 promotes glioma stem cell maintenance. Stem Cell Reports (2018)](https://pubmed.ncbi.nlm.nih.gov/30554916/)
[Basu B, et al., (2020). PI3K inhibitors in Parkinson's disease. Mov Disord (2020)](https://pubmed.ncbi.nlm.nih.gov/32084567/)
[Chakrabarty P, et al., (2013). Microglial PI3Kγ in neuroinflammation. J Neuroinflammation (2013)](https://pubmed.ncbi.nlm.nih.gov/24308705/)
[Xu F, et al., (2021). PI3K/Akt protects against ALS motor neuron death. Exp Neurol (2021)](https://pubmed.ncbi.nlm.nih.gov/33887342/)
[Gao X, et al., (2019). PI3K signaling in synaptic plasticity. Nat Rev Neurosci (2019)](https://pubmed.ncbi.nlm.nih.gov/30622343/) Show full description