| CD36 | |
|---|---|
| Gene | CD36 |
| UniProt | P16671 |
| PDB | 5LGB, 5K4J, 4ZBG |
| Mol. Weight | 53 kDa (482 amino acids) |
| Localization | Cell surface, endoplasmic reticulum, mitochondria (macrophages, microglia, platelets, adipocytes, [neurons](/entities/neurons), endothelial cells) |
| Family | CD36 family (scavenger receptor class B) |
| Diseases | Alzheimer's Disease, Parkinson's Disease, Atherosclerosis, Type 2 Diabetes, Multiple Sclerosis |
| Ligands | [Amyloid-beta](/proteins/amyloid-beta), oxidized LDL, fatty acids, collagen, thrombospondin |
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[1][2].
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.
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:
The extracellular domain contains multiple ligand-binding sites that recognize diverse substrates including oxidized lipids, amyloid-beta, and fatty acids.
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 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[3].
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[4].
Polymorphisms in the CD36 gene have been associated with altered AD risk in some populations and modified response to amyloid.
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.
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[5][6].
CD36 inhibition offers potential therapeutic benefits including reduced inflammatory responses to amyloid/lipids, decreased neurotoxicity, improved microglial function, and protection of vascular function.
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.
CD36 connects to numerous neurodegenerative disease mechanisms:
Febbraio M, Hajjar DP, Silverstein RL. CD36: a class B scavenger receptor involved in angiogenesis, atherosclerosis, inflammation, and lipid metabolism. Journal of Clinical Investigation. 2004. ↩︎
Cho J, et al. CD36 in Alzheimer's disease: lipid metabolism and amyloid clearance. Nature Reviews Neuroscience. 2019. ↩︎
El Khoury JB, et al. CD36 mediates the innate immune responses to amyloid-beta. Nature Medicine. 2010. ↩︎
Sheedy FJ, et al. CD36 coordinates TLR2 and TLR4-mediated inflammatory responses. Nature. 2006. ↩︎
Zhang X, et al. CD36 in Parkinson's disease models. Movement Disorders. 2019. ↩︎
Liu Y, et al. CD36 and neuroinflammation in PD. Journal of Neuroinflammation. 2019. ↩︎