CD36 Protein (Cluster of Differentiation 36)

CD36 Protein (Cluster of Differentiation 36)

Pathway Diagram

```mermaid
flowchart TD
AmyloidBeta["Amyloid beta<br/>Protein"]
CD36["CD36<br/>Scavenger Receptor"]
PINK1["PINK1<br/>Mitochondrial Kinase"]
Pericytes["Pericytes<br/>BBB Support Cells"]

Inflammation["Inflammation<br/>Process"]
Neuroinflammation["Neuroinflammation<br/>CNS Inflammation"]

Alzheimer["Alzheimer's<br/>Disease"]
ALS["ALS<br/>Disease"]
MS["Multiple<br/>Sclerosis"]
Stroke["Stroke<br/>Cerebrovascular"]

BBBDysfunction["BBB Dysfunction<br/>Barrier Breakdown"]
MitochondrialDysfunction["Mitochondrial<br/>Dysfunction"]
VascularPathology["Vascular<br/>Pathology"]

AmyloidBeta -->|"activates"| CD36
CD36 -->|"activates"| PINK1
CD36 -->|"promotes"| Pericytes
CD36 -->|"regulates"| Pericytes

CD36 -->|"activates"| Inflammation
CD36 -->|"activates"| Neuroinflammation

CD36 -->|"interacts_with"| Alzheimer
CD36 -->|"inhibits"| ALS
CD36 -->|"activates"| MS
CD36 -->|"associated_with"| Stroke

Pericytes -->|"dysfunction_leads_to"| BBBDysfunction
PINK1 -->|"dysfunction_leads_to"| MitochondrialDysfunction
CD36 -->|"contributes_to"| VascularPathology

BBBDysfunction -->|"contributes_to"| Alzheimer
MitochondrialDysfunction -->|"contributes_to"| ALS
VascularPathology -->|"contributes_to"| Stroke
Neuroinflammation -->|"drives"| MS

style CD36 fill:#006494
style PINK1 fill:#4a1a6b
style Pericytes fill:#1b5e20
style AmyloidBeta fill:#ef5350
style In

CD36 Protein (Cluster of Differentiation 36)

Pathway Diagram

<table class="infobox infobox-protein">
<tr>
<th class="infobox-header" colspan="2">CD36</th>
</tr>
<tr>
<td class="label">Gene</td>
<td><a href="/genes/cd36">CD36</a></td>
</tr>
<tr>
<td class="label">UniProt</td>
<td><a href="https://www.uniprot.org/uniprot/P16671" target="_blank">P16671</a></td>
</tr>
<tr>
<td class="label">PDB</td>
<td><a href="https://www.rcsb.org/structure/5LGB" target="_blank">5LGB</a>, <a href="https://www.rcsb.org/structure/5K4J" target="_blank">5K4J</a>, <a href="https://www.rcsb.org/structure/4ZBG" target="_blank">4ZBG</a></td>
</tr>
<tr>
<td class="label">Mol. Weight</td>
<td>53 kDa (482 amino acids)</td>
</tr>
<tr>
<td class="label">Localization</td>
<td>Cell surface, endoplasmic reticulum, mitochondria (macrophages, microglia, platelets, adipocytes, neurons, endothelial cells)</td>
</tr>
<tr>
<td class="label">Family</td>
<td>CD36 family (scavenger receptor class B)</td>
</tr>
<tr>
<td class="label">Diseases</td>
<td><a href="/diseases/alzheimers">Alzheimer's Disease</a>, <a href="/diseases/parkinsons-disease">Parkinson's Disease</a>, <a href="/diseases/atherosclerosis">Atherosclerosis</a>, <a href="/diseases/type-2-diabetes">Type 2 Diabetes</a>, Multiple Sclerosis</td>
</tr>
<tr>
<td class="label">Ligands</td>
<td>Amyloid-beta, oxidized LDL, fatty acids, collagen, thrombospondin</td>
</tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/als" style="color:#ef9a9a">ALS</a>, <a href="/wiki/amyloid" style="color:#ef9a9a">AMYLOID</a>, <a href="/wiki/als" style="color:#ef9a9a">Als</a>, <a href="/wiki/alzheimer" style="color:#ef9a9a">Alzheimer</a>, <a href="/wiki/atherosclerosis" style="color:#ef9a9a">Atherosclerosis</a></td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">279 edges</a></td>
</tr>
</table>

CD36 (Cluster of Differentiation 36)

Overview

CD36 (Cluster of Differentiation 36) is a class B scavenger receptor that functions as a multi-ligand membrane glycoprotein involved in diverse biological processes including lipid metabolism, immune responses, cellular adhesion, and angiogenesis. Originally identified as a platelet surface glycoprotein (GPIV), CD36 has emerged as a critical player in the pathogenesis of neurodegenerative diseases, particularly through its role in amyloid-beta clearance, neuroinflammation, and lipid homeostasis in the brain[@febbraio2004][@cho2019].

This review examines the structure and function of CD36, its expression in the central nervous system, and its contributions to Alzheimer's disease (AD), Parkinson's disease (PD), and related neurodegenerative disorders.

Structure and Molecular Biology

Gene and Protein Structure

The CD36 gene is located on chromosome 7q11.2 and encodes a 472-amino acid protein with a molecular weight of approximately 53 kDa. The protein contains:

• N-terminal cytoplasmic domain (6-10 amino acids)
• Transmembrane regions (two short helices)
• Large extracellular loop (~300 amino acids) containing ligand-binding sites
• C-terminal cytoplasmic tail (~10 amino acids)

Expression and Localization in the Brain

Cellular Distribution

CD36 is expressed in multiple cell types within the central nervous system:

Microglia:
CD36 is highly expressed in microglia, the resident immune cells of the brain. It serves as a pattern recognition receptor for pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs). Microglial CD36 mediates recognition and phagocytosis of Aβ aggregates and production of pro-inflammatory cytokines.

Neurons:
Neuronal expression of CD36 is lower than in microglia but increases in disease states. In neurons, CD36 participates in fatty acid uptake and metabolism, synaptic plasticity, and response to metabolic stress.

Endothelial Cells:
CD36 is expressed on brain microvascular endothelial cells where it mediates amyloid-beta transport across the blood-brain barrier and vascular inflammation.

CD36 in Alzheimer's Disease

Amyloid Metabolism

CD36 plays complex roles in amyloid-beta metabolism in AD:

Clearance and Phagocytosis:
Microglial CD36 participates in amyloid-beta clearance through direct binding and phagocytosis of Aβ aggregates, collaboration with TLRs to enhance phagocytosis, and activation of the NLRP3 inflammasome.

However, chronic exposure to amyloid leads to CD36-mediated inflammation that paradoxically impairs effective clearance. The inflammatory response includes pro-inflammatory cytokine production, migration inhibition, and phagolysosomal dysfunction[@elkhoury2010].

Neuroinflammation

CD36 is a key mediator of neuroinflammation in AD. CD36 acts as a co-receptor for TLR2 and TLR4, coordinating innate immune responses to amyloid. This synergy amplifies inflammatory signaling and cytokine production[@sheedy2006].

Genetic Associations

Polymorphisms in the CD36 gene have been associated with altered AD risk in some populations and modified response to amyloid.

CD36 in Parkinson's Disease

Alpha-Synuclein and Neuroinflammation

CD36 contributes to Parkinson's disease through several mechanisms. Like Aβ in AD, α-synuclein aggregates activate microglia through CD36. This activation triggers pro-inflammatory cytokine production, promotes oxidative stress, and contributes to dopaminergic neuron toxicity.

Evidence from Models

Preclinical models demonstrate CD36 involvement in PD: CD36 knockout mice show altered responses to MPTP, CD36 deficiency affects alpha-synuclein-induced inflammation, and CD36 contributes to toxin-induced dopaminergic degeneration[@zhang2019][@liu2019].

Therapeutic Targeting

Rationale for Inhibition

CD36 inhibition offers potential therapeutic benefits including reduced inflammatory responses to amyloid/lipids, decreased neurotoxicity, improved microglial function, and protection of vascular function.

Therapeutic Approaches

Small Molecule Inhibitors:
Several CD36 inhibitors have been developed including sulfatide analogs, oxLDL-binding compounds, and synthetic antagonists.

Antibody-Based Approaches:
Anti-CD36 antibodies can block ligand binding and signaling. Challenges include blood-brain barrier penetration and target engagement in microglia.

Cross-Linking to Related Topics

CD36 connects to numerous neurodegenerative disease mechanisms:

• [Amyloid-beta](/mechanisms/amyloid-pathology) - CD36 in Aβ clearance and inflammation
• [Microglia](/cell-types/microglia-neuroinflammation) - Primary CD36-expressing cells in brain
• [Neuroinflammation](/mechanisms/neuroinflammation-alzheimers) - CD36-mediated inflammatory responses
• [TLR Signaling](/mechanisms/toll-like-receptor-signaling) - CD36 as TLR co-receptor
• [Lipid Metabolism](/mechanisms/lipid-metabolism-alzheimers) - CD36 in fatty acid transport
• [TREM2](/proteins/trem2-protein) - Complementary microglial receptor

See Also

• [Microglia](/cell-types/microglia-neuroinflammation)
• [Amyloid-beta](/mechanisms/amyloid-pathology)
• [Neuroinflammation](/mechanisms/neuroinflammation-alzheimers)
• [Alzheimer's Disease](/diseases/alzheimers-disease)
• [Parkinson's Disease](/diseases/parkinsons-disease)
• [TREM2](/proteins/trem2-protein)

External Links

• [UniProt - CD36](https://www.uniprot.org/uniprot/P16671)
• [PDB - CD36 Structures](https://www.rcsb.org/structure/5LGB)
• [PubMed - CD36 Neurodegeneration](https://pubmed.ncbi.nlm.nih.gov/?term=CD36+Alzheimer+Parkinson)

References