Apoer2 Protein is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.
ApoER2 (Apolipoprotein E Receptor 2), also known as LRP8, is a member of the Low-Density Lipoprotein Receptor family. It is primarily expressed in the brain and plays critical roles in synaptic function, neuronal development, and lipid metabolism. ApoER2 is a key receptor for both Reelin signaling and apolipoprotein E (APOE)-containing lipoproteins, making it a crucial nexus between lipid metabolism and neuronal function. The receptor is expressed predominantly in neurons throughout the brain, with highest levels in the hippocampus, cortex, and cerebellum.
| Attribute |
Value |
| Gene Symbol |
LRP8 |
| Protein Name |
Apolipoprotein E Receptor 2 (ApoER2) |
| Molecular Weight |
~110 kDa (full-length), 85 kDa (truncated) |
| Structure |
963 amino acids |
| Aliases |
LDLRR, LR8, APOER2 |
| UniProt ID |
Q9UBJ2 |
| Tissue Expression |
Brain (neurons), testis, platelets |
ApoER2 is a type I transmembrane glycoprotein with multiple functional domains:
¶ Extracellular Domain
- Ligand-Binding Repeats (8): Cys-rich repeats that bind Reelin and APOE
- EGF-Like Repeats (3): Required for pH-dependent ligand release
- Truncated Isoforms: Brain-expressed isoforms lack some repeats
¶ Transmembrane Domain
- Single alpha-helical transmembrane segment
- Links extracellular and intracellular domains
- NPXY Internalization Signals: Two NPXY motifs for endocytosis
- Tyrosine Phosphorylation Sites: Critical for downstream signaling
- Dileucine Motif: Additional sorting signal
ApoER2 is the primary Reelin receptor in neurons:
- Reelin binds to ApoER2 (and VLDLR) with high affinity
- Triggers Dab1 phosphorylation cascade
- Inhibits glycogen synthase kinase-3β (GSK-3β)
- Promotes microtubule stabilization
- Enhances NMDA receptor function
- Facilitates synaptic plasticity
- Binds APOE-containing lipoproteins (primarily APOE4 isoform)
- Mediates neuronal cholesterol uptake
- Participates in brain lipid homeostasis
- Regulates synaptic membrane composition
- Co-localizes with NMDA receptors at synapses
- Enhances NMDA receptor phosphorylation
- Potentiates NMDA-mediated calcium influx
- Critical for LTP and memory formation
- Hippocampus: Highest expression in CA1 pyramidal neurons
- Cerebral Cortex: Layer-specific expression patterns
- Cerebellum: Purkinje cells and granule cells
- Basal Ganglia: Moderate expression
- Highest expression during embryonic development
- Continues in adult brain
- Regulated by neuronal activity
- Genetic Variants: LRP8 polymorphisms modify AD risk
- Aβ Metabolism: Affects amyloid-beta clearance
- APOE4 Interaction: APOE4-ApoER2 signaling is impaired
- Synaptic Dysfunction: Contributes to memory deficits
- Therapeutic Target: Reelin/ApoER2 signaling enhancement
- Mutations cause autosomal recessive intellectual disability
- Impaired Reelin signaling disrupts neuronal migration
- Associated with cortical malformations
- Comorbidities: epilepsy, motor deficits
¶ Stroke and Cerebrovascular Disease
- LRP8 polymorphisms modulate stroke risk
- May affect cerebral vascular integrity
- APOE4-ApoER2 interaction in vascular dementia
- Potential for cerebrovascular therapeutics
- Expressed in vascular smooth muscle cells
- May affect systemic lipid metabolism
- Interaction with circulating lipoproteins
- Reelin binds to ApoER2/VLDLR receptor complex
- Src family kinases phosphorylate Dab1
- Dab1 recruits PI3K and downstream effectors
- Akt/PKB activation inhibits GSK-3β
- Reduced tau phosphorylation
- Enhanced synaptic plasticity
| Partner |
Interaction Type |
Functional Consequence |
| Reelin |
Ligand binding |
Neuronal migration, plasticity |
| VLDLR |
Co-receptor |
Signal amplification |
| Dab1 |
Adaptor protein |
Signal transduction |
| APOE |
Ligand binding |
Lipid transport |
| NMDA Receptor |
Physical association |
Synaptic modulation |
| PSD-95 |
Scaffold interaction |
Synaptic localization |
| Approach |
Status |
Mechanism |
| Reelin mimetics |
Preclinical |
Activate ApoER2 signaling |
| Dab1 stabilizers |
Discovery |
Enhance downstream signaling |
| Small molecule modulators |
Preclinical |
Modulate receptor activity |
- Gene therapy for LRP8 mutations
- AAV-mediated Reelin delivery
- Peptide agonists for ApoER2
- Combination with APOE-targeting therapies
- ApoER2 Knockout Mice: Mild neurological phenotype, enhanced LTP deficits with APOE4
- Conditional Knockouts: Region-specific deletion studies
- Transgenic Overexpression: Rescue of synaptic deficits
- Defining isoform-specific functions
- Developing brain-penetrant small molecules
- Understanding APOE4-ApoER2 interaction in AD
- Biomarker potential: soluble ApoER2 as marker
The study of Apoer2 Protein 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.
- Trommsdorff et al., 1999. Reelin and ApoER2 in neuronal migration. Nature. PMID:10436159
- Herz and Chen, 2006. LRP8 in neurodegeneration. Nat Rev Neurosci. PMID:16641937
- Lane-Donovan et al., 2014. Lipoprotein receptors in brain function. Annu Rev Physiol. PMID:25148686
- Beffert et al., 2005. ApoER2 and Reelin in synaptic plasticity. Neuron. PMID:15953421
- D'Arcangelo et al., 2009. Reelin signaling in neuropsychiatric disease. Nat Rev Neurosci. PMID:19680242
- Chen et al., 2010. LRP8 and Alzheimer's disease. J Neurosci. PMID:20463221
- Hiesberger et al., 1999. Direct binding of Reelin to ApoER2. Nature. PMID:10436158
- Bal et al., 2013. ApoER2 and NMDA receptor function. Nat Neurosci. PMID:24162653