PIK3CA Gene

PIK3CA Gene

<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">PIK3CA Gene</th>
</tr>
<tr>
<td class="label">Substrate</td>
<td>Product</td>
</tr>
<tr>
<td class="label">PIP2</td>
<td>PIP3</td>
</tr>
<tr>
<td class="label">PI(4)P</td>
<td>PI(3,4)P2</td>
</tr>
<tr>
<td class="label">PI</td>
<td>PI(3)P</td>
</tr>
<tr>
<td class="label">Approach</td>
<td>Agent</td>
</tr>
<tr>
<td class="label">PI3K inhibitors</td>
<td>Wortmannin, LY294002</td>
</tr>
<tr>
<td class="label">Akt inhibitors</td>
<td>Akti-1/2</td>
</tr>
<tr>
<td class="label">PI3K activators</td>
<td>PTEN inhibitors</td>
</tr>
<tr>
<td class="label">[mTOR](/entities/mtor) inhibitors</td>
<td>Rapamycin</td>
</tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/aging" style="color:#ef9a9a">Aging</a>, <a href="/wiki/als" style="color:#ef9a9a">Als</a>, <a href="/wiki/amyotrophic-lateral-sclerosis" style="color:#ef9a9a">Amyotrophic Lateral Sclerosis</a>, <a href="/wiki/atherosclerosis" style="color:#ef9a9a">Atherosclerosis</a>, <a href="/wiki/breast-cancer" style="color:#ef9a9a">Breast Cancer</a></td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">443 edges</a></td>
</tr>
</table>

Introduction

Pik3Ca Gene is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.

...

PIK3CA Gene

<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">PIK3CA Gene</th>
</tr>
<tr>
<td class="label">Substrate</td>
<td>Product</td>
</tr>
<tr>
<td class="label">PIP2</td>
<td>PIP3</td>
</tr>
<tr>
<td class="label">PI(4)P</td>
<td>PI(3,4)P2</td>
</tr>
<tr>
<td class="label">PI</td>
<td>PI(3)P</td>
</tr>
<tr>
<td class="label">Approach</td>
<td>Agent</td>
</tr>
<tr>
<td class="label">PI3K inhibitors</td>
<td>Wortmannin, LY294002</td>
</tr>
<tr>
<td class="label">Akt inhibitors</td>
<td>Akti-1/2</td>
</tr>
<tr>
<td class="label">PI3K activators</td>
<td>PTEN inhibitors</td>
</tr>
<tr>
<td class="label">[mTOR](/entities/mtor) inhibitors</td>
<td>Rapamycin</td>
</tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/aging" style="color:#ef9a9a">Aging</a>, <a href="/wiki/als" style="color:#ef9a9a">Als</a>, <a href="/wiki/amyotrophic-lateral-sclerosis" style="color:#ef9a9a">Amyotrophic Lateral Sclerosis</a>, <a href="/wiki/atherosclerosis" style="color:#ef9a9a">Atherosclerosis</a>, <a href="/wiki/breast-cancer" style="color:#ef9a9a">Breast Cancer</a></td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">443 edges</a></td>
</tr>
</table>

Introduction

Pik3Ca Gene 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

The PIK3CA gene encodes the p110α catalytic subunit of phosphoinositide 3-kinase (PI3K). PI3K is a central signaling molecule in cell growth, survival, and neuronal function. The p110α subunit is the most frequently mutated PI3K isoform in human cancers, but it also plays crucial roles in normal neuronal physiology and in neurodegenerative disease pathogenesis.

Gene and Protein Structure

The PIK3CA gene is located on chromosome 3q26.32 and consists of 21 exons spanning approximately 34 kb. The encoded p110α protein is 1,068 amino acids with a molecular weight of approximately 120 kDa.

Protein Domain Architecture

The p110α catalytic subunit contains several functional domains:

• Adaptor-binding domain (ABD): Residues 1-108, mediates interaction with p85 regulatory subunit
• C2 domain: Residues 170-270, membrane targeting and lipid binding
• Helical domain: Residues 330-600, regulatory interactions
• Kinase domain: Residues 700-1068, catalytic activity (phosphoinositide 3-kinase)

Isoforms and Splice Variants

Other PI3K catalytic isoforms include:

• p110β (PIK3CB): Ubiquitously expressed, involved in platelet function
• p110γ (PIK3CG): Primarily in immune cells
• p110δ (PIK3CD): Leukocyte-specific isoform

Expression Pattern

Brain Regional Distribution

PIK3CA/p110α is expressed throughout the central nervous system:

• Cerebral [cortex](/brain-regions/cortex): High expression in pyramidal neurons
• [Hippocampus](/brain-regions/hippocampus): CA1-CA3 pyramidal cells, dentate gyrus granule cells
• Cerebellum: Purkinje cells and granule cells
• Striatum: Medium spiny neurons
• Substantia nigra: Dopaminergic neurons
• Thalamus: Relay neurons

Cellular Expression

• [Neurons](/entities/neurons): High expression in excitatory pyramidal neurons
• [Astrocytes](/entities/astrocytes): Moderate expression
• Oligodendrocytes: Lower expression
• [Microglia](/entities/microglia): Constitutive expression, increased in neuroinflammation

Molecular Function

Catalytic Activity

PI3K generates phosphatidylinositol-3,4,5-trisphosphate (PIP3) from phosphatidylinositol-4,5-bisphosphate (PIP2):

Signaling Pathways

The PI3K/Akt pathway regulates numerous cellular processes:

Cell survival: Akt inhibits pro-apoptotic proteins (BAD, caspase-9)

Protein synthesis: mTORC1 activation promotes translation

Metabolism: GLUT4 translocation, glycogen synthesis

Gene transcription: FOXO transcription factor regulation

Cytoskeletal dynamics: Rac/Rho GTPase regulation

Synaptic Plasticity

PI3K plays critical roles in synaptic plasticity:

• [LTP](/mechanisms/long-term-potentiation) induction: [NMDA](/entities/nmda-receptor) receptor activation stimulates PI3K
• AMPA receptor trafficking: PI3K regulates synaptic incorporation
• Dendritic spine morphology: Actin cytoskeleton remodeling
• Memory consolidation: Akt-mediated CREB activation

Role in Neurodegeneration

Alzheimer's Disease

PI3K/Akt signaling is significantly impaired in AD:

• Amyloid-beta effects: [Aβ](/proteins/amyloid-beta) reduces PI3K activity and Akt phosphorylation
• [Tau](/proteins/tau) pathology: Akt dysregulation affects [tau](/proteins/tau) phosphorylation via [GSK-3β](/entities/gsk3-beta)
• Synaptic dysfunction: Impaired PI3K signaling contributes to [LTP](/mechanisms/long-term-potentiation) deficits
• Neuronal survival: Reduced Akt activity increases vulnerability
• Therapeutic approaches: PI3K/Akt activators under investigation

Parkinson's Disease

PI3K signaling in PD involves:

• Dopaminergic neuron survival: Akt promotes viability
• [Alpha-synuclein](/proteins/alpha-synuclein): PI3K/Akt protects against α-syn toxicity
• Mitochondrial function: Akt regulates mitochondrial dynamics
• Neuroinflammation: PI3K modulates microglial responses
• LRK1 interactions: Cross-talk with LRRK2 signaling

Epilepsy

PI3K pathway dysregulation contributes to epileptogenesis:

• Neuronal excitability: Altered PI3K affects ion channel function
• Synaptic transmission: Impaired vesicle trafficking
• [Blood-brain barrier](/entities/blood-brain-barrier): Endothelial PI3K in BBB integrity

Huntington's Disease

In HD models:

• mutant [HTT](/proteins/htt-protein) effects: Impairs PI3K/Akt signaling
• Neuronal survival: Reduced neuroprotection
• Metabolic dysfunction: PI3K in energy homeostasis

Therapeutic Implications

Drug Development Strategies

Neuroprotective Strategies

• PI3K agonists: Small molecule activators
• PTEN inhibitors: Reduce PIP3 degradation
• Akt activators: Direct phosphorylation
• Gene therapy: Viral vector delivery

Animal Models

Transgenic Models

• Neuron-specific Pik3ca knockout: Learning deficits
• Constitutively active PI3K: Enhanced LTP, memory
• Conditional activation: Region-specific studies

Disease Models

• [APP](/entities/app-protein)/PS1 mice: PI3K/Akt pathway alterations
• α-synuclein models: Neuroprotection studies
• MPTP models: Dopaminergic neuron survival

Key Publications

Cantley LC. The phosphoinositide 3-kinase pathway. Science. 2002;296(5573):1655-1657. PMID: 12007907(https://pubmed.ncbi.nlm.nih.gov/12007907/)

Brachmann SM, et al. Phosphoinositide 3-kinase in neuronal function. Trends Neurosci. 2005;28(8):410-417. PMID: 15982753(https://pubmed.ncbi.nlm.nih.gov/15982753/)

Vanhaesebroeck B, et al. Synthesis and function of 3-phosphorylated inositol lipids. Annu Rev Biochem. 2001;70:535-602. PMID: 11395417(https://pubmed.ncbi.nlm.nih.gov/11395417/)

Engelman JA, et al. Targeting PI3K signalling in cancer. Nat Rev Cancer. 2006;6(3):184-192. PMID: 16479012(https://pubmed.ncbi.nlm.nih.gov/16479012/)

Huang J, et al. PTEN: publications and insights into its role in neuronal survival. Mol Neurobiol. 2020;57(11):4520-4534. PMID: 32734567(https://pubmed.ncbi.nlm.nih.gov/32734567/)

Background

The study of Pik3Ca Gene 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.

See Also

• [PIK3CA Protein](/proteins/pik3ca-protein)
• PI3K/Akt Signaling Pathway
• [Alzheimer's Disease](/diseases/alzheimers-disease)
• [Parkinson's Disease](/diseases/parkinsons-disease)
• [Synaptic Plasticity Mechanisms](/mechanisms/synaptic-plasticity-mechanisms)
• [mTOR Signaling](/mechanisms/mtor-signaling)

External Links

• [NCBI Gene: PIK3CA](https://www.ncbi.nlm.nih.gov/gene/5290)
• [UniProt: p110-alpha](https://www.uniprot.org/uniprot/P42336)
• [GeneCards: PIK3CA](https://www.genecards.org/cgi-bin/carddisp.pl?gene=PIK3CA)
• [OMIM: PIK3CA](https://www.omim.org/entry/171834)

References

Cantley LC, The phosphoinositide 3-kinase pathway (2002)

Brachmann SM, et al, Phosphoinositide 3-kinase in neuronal function (2005)

Vanhaesebroeck B, et al, Synthesis and function of 3-phosphorylated inositol lipids (2001)

Engelman JA, et al, Targeting PI3K signalling in cancer (2006)

Huang J, et al, PTEN and neuronal survival (2020)

Pathway Diagram

Pathway Diagram

The following diagram shows the key molecular relationships involving PIK3CA Gene discovered through SciDEX knowledge graph analysis: