RELN — Reelin
Pathway Diagram
Mermaid diagram (expand to render)
Overview
Reln Gene plays an important role in the study of neurodegenerative diseases. This page provides comprehensive information about this topic, including its mechanisms, significance in disease processes, and therapeutic implications.
Introduction
RELN (Reelin) is a gene encoding the extracellular matrix protein reelin, one of the largest secreted proteins in the brain (approximately 400 kDa). Reelin plays fundamental roles in brain development, neuronal migration, synaptic plasticity, and cognitive function. Dysregulation of RELN expression and function has been strongly implicated in Alzheimer's disease (AD), Parkinson's disease (PD), schizophrenia, autism spectrum disorder, and lissencephaly [1](https://pubmed.ncbi.nlm.nih.gov/31997389/). [@nakano2017]
<div class="infobox infobox-gene"> [@alcntara2018]
<table> [@weeber2002]
<tr><th colspan="2" style="background:#e8f4f8; text-align:center; font-size:1.1em;">Reelin</th></tr> [@trommsdorff2004]
<tr><td><strong>Gene Symbol</strong></td><td>RELN</td></tr> [@bock2009]
<tr><td><strong>Full Name</strong></td><td>Reelin</td></tr> [@beffert2012]
<tr><td><strong>Chromosome</strong></td><td>7q22.1</td></tr> [@zhou2018]
<tr><td><strong>NCBI Gene ID</strong></td><td>[5649](https://www.ncbi.nlm.nih.gov/gene/5649)</td></tr> [@chen2005]
<tr><td><strong>OMIM</strong></td><td>[600514](https://www.omim.org/entry/600514)</td></tr> [@hong1995]
<tr><td><strong>Ensembl ID</strong></td><td>ENSG00000189056</td></tr> [@frotscher2009]
<tr><td><strong>UniProt ID</strong></td><td>[P78509](https://www.uniprot.org/uniprot/P78509)</td></tr> [@chen2005a]
<tr><td><strong>Associated Diseases</strong></td><td>Alzheimer's Disease, Parkinson's Disease, Lissencephaly, Schizophrenia, Autism</td></tr> [@schuste2016]
</table> [@alcntara2018a]
</div> [@puelles2019a]
Function
Protein Structure and Secretion
Reelin is a large extracellular glycoprotein composed of multiple repeat domains. The protein contains an N-terminal signal peptide followed by 8 reelin repeat domains (R1-R8), each approximately 350 amino acids in length. The C-terminal region contains a cysteine-rich domain that is essential for receptor binding [2](https://pubmed.ncbi.nlm.nih.gov/28726847/). [@botellalpez2008]
Reelin is primarily secreted by Cajal-Retzius cells located in the marginal zone of the developing cerebral [cortex](/brain-regions/cortex). In the adult brain, reelin is also produced by GABAergic interneurons, particularly in the [hippocampus](/brain-regions/hippocampus) and cerebellum. The protein is secreted into the extracellular matrix where it can diffuse and act on target [neurons](/entities/neurons) [3](https://pubmed.ncbi.nlm.nih.gov/25889337/). [@muta2012]
Receptor Binding and Signaling Pathways
Reelin exerts its effects by binding to two main receptor proteins on the neuronal surface: [@fatemi2005]
Very Low-Density Lipoprotein Receptor (VLDLR): Expressed in migrating neurons and mature neurons, VLDLR mediates reelin signaling involved in neuronal positioning and synaptic function [4](https://pubmed.ncbi.nlm.nih.gov/12446774/).
ApoER2 (LRP8): Expressed in hippocampal and cortical neurons, ApoER2 is crucial for reelin-mediated synaptic plasticity and memory formation [5](https://pubmed.ncbi.nlm.nih.gov/12446774/).Upon reelin binding, these receptors cluster and activate downstream intracellular signaling cascades: [@pesold2018]
- Disabled-1 (DAB1) phosphorylation: The adaptor protein DAB1 binds to the cytoplasmic tails of VLDLR and ApoER2. Reelin binding induces tyrosine phosphorylation of DAB1, which is essential for downstream signaling [6](https://pubmed.ncbi.nlm.nih.govPMC2882708/).
- PI3K/Akt pathway: Phosphorylated DAB1 activates PI3K, leading to Akt phosphorylation. This pathway promotes neuronal survival and regulates glycogen synthase kinase-3β (GSK-3β) activity [7](https://pubmed.ncbi.nlm.nih.gov/22170047/).
- [mTOR](/mechanisms/mtor-signaling-pathway) signaling: Reelin activates mTORC1 and mTORC2, regulating protein synthesis and synaptic plasticity [8](https://pubmed.ncbi.nlm.nih.gov/29545227/).
- [NMDA receptor](/entities/nmda-receptor) modulation: Reelin enhances NMDA receptor function through ApoER2-mediated signaling, facilitating synaptic plasticity and [long-term potentiation](/mechanisms/long-term-potentiation) (LTP) [9](https://pubmed.ncbi.nlm.nih.gov/15591051/).
Role in Neuronal Migration
During cortical development, reelin guides radially migrating neurons from the ventricular zone to their final positions in the cortical plate. This process, known as "inside-out" lamination, ensures proper cortical layering. Neurons lacking reelin or functional receptors fail to migrate properly, resulting in cortical malformation [10](https://pubmed.ncbi.nlm.nih.gov/8645281/). [@beffert2012a]
Synaptic Plasticity and Cognitive Function
In the adult brain, reelin continues to play critical roles in synaptic maintenance and plasticity: [@botellalpez2008a]
- Dendritic spine formation: Reelin promotes the formation and maintenance of [dendritic spines](/mechanisms/dendritic-spines), the primary sites of excitatory synaptic transmission [11](https://pubmed.ncbi.nlm.nih.gov/19535918/).
- Long-term potentiation (LTP): Reelin enhances LTP through NMDA receptor modulation, a cellular correlate of learning and memory [12](https://pubmed.ncbi.nlm.nih.gov/15591051/).
- Synaptic scaling: Reelin regulates homeostatic synaptic scaling, helping neurons maintain stable firing rates despite changes in activity [13](https://pubmed.ncbi.nlm.nih.gov/25828855/).
Expression
Developmental Expression
During embryonic development, reelin is highly expressed in Cajal-Retzius cells in the marginal zone of the cortex, the subplate, and the hippocampal stratum radiatum. This expression pattern guides the radial migration of neurons forming the characteristic six-layer cortical structure [14](https://pubmed.ncbi.nlm.nih.gov/25889337/). [@puelles2019b]
Adult Brain Expression
In the adult brain, reelin expression shifts to GABAergic interneurons, particularly:
- Parvalbumin-positive interneurons in the cortex
- Calretinin-positive interneurons in the hippocampus
- Cerebellar basket cells in the cerebellum
Reelin continues to be secreted at synapses, where it modulates plasticity and stability [15](https://pubmed.ncbi.nlm.nih.gov/25889337/).
Expression in Disease States
Alterations in RELN expression are observed in several neurodegenerative and psychiatric disorders:
- Alzheimer's disease: Reelin expression is reduced in the [entorhinal cortex](/brain-regions/entorhinal-cortex) and hippocampus of AD patients, particularly in early stages [16](https://pubmed.ncbi.nlm.nih.gov/17656456/).
- Parkinson's disease: Reduced reelin immunoreactivity has been reported in the striatum of PD patients [17](https://pubmed.ncbi.nlm.nih.gov/22472201/).
- Schizophrenia: Postmortem studies show decreased reelin expression in the prefrontal cortex and hippocampus of schizophrenic patients [18](https://pubmed.ncbi.nlm.nih.gov/15601780/).
Disease Associations
Alzheimer's Disease
Reelin plays a complex role in Alzheimer's disease pathogenesis:
- [Amyloid-beta](/proteins/amyloid-beta) interaction: Reelin can bind to amyloid-beta (Aβ) oligomers and potentially modulate Aβ toxicity. However, Aβ can also impair reelin signaling, creating a detrimental feedback loop [19](https://pubmed.ncbi.nlm.nih.gov/28628077/).
- [Tau](/proteins/tau) phosphorylation: Reelin signaling through [GSK-3β](/entities/gsk3-beta) can influence tau phosphorylation. Dysregulated reelin signaling may contribute to tau pathology in AD [20](https://pubmed.ncbi.nlm.nih.gov/22170047/).
- Synaptic vulnerability: Reduced reelin in AD compromises synaptic stability and plasticity, contributing to cognitive decline [21](https://pubmed.ncbi.nlm.nih.gov/17656456/).
- Therapeutic potential: Enhancing reelin signaling is being explored as a therapeutic strategy for AD. Small molecules that activate reelin receptors or stabilize reelin are under investigation [22](https://pubmed.ncbi.nlm.nih.gov/31997389/).
| Disease | Variants | Inheritance | Mechanism |
|---------|----------|-------------|-----------|
| Lissencephaly | Missense, nonsense | Autosomal recessive | Impaired neuronal migration, cortical layering defects |
| Schizophrenia | Promoter variants, risk SNPs | Susceptibility | Altered synaptic function, GABAergic dysfunction |
| Autism | Rare missense variants | De novo | Impaired neural circuit formation |
| Alzheimer's Disease | Expression downregulated | Acquired | Synaptic dysfunction, Aβ interaction |
Parkinson's Disease
In PD, reelin expression is reduced in key brain regions:
- The striatum shows decreased reelin immunoreactivity, potentially contributing to dopaminergic dysfunction
- Reelin may protect dopaminergic neurons from oxidative stress
- Reduced reelin signaling may exacerbate tau pathology in PD [17](https://pubmed.ncbi.nlm.nih.gov/22472201/)
Lissencephaly
Homozygous or compound heterozygous mutations in RELN cause lissencephaly with cerebellar hypoplasia. These mutations impair reelin secretion or function, leading to severe cortical malformation [10](https://pubmed.ncbi.nlm.nih.gov/8645281/).
Schizophrenia and Autism
Both schizophrenia and autism show reduced RELN expression in the brain:
- Epigenetic regulation: Promoter hypermethylation of RELN has been documented in both disorders
- GABAergic dysfunction: Reduced reelin affects GABAergic interneuron function
- Synaptic pathology: Altered reelin signaling contributes to synaptic dysfunction [18](https://pubmed.ncbi.nlm.nih.gov/15601780/)
Therapeutic Implications
Reelin-Based Therapies
Several therapeutic strategies targeting reelin signaling are under development:
Reelin mimetics: Peptide fragments that replicate reelin's receptor-binding activity
Small molecule agonists: Compounds that activate VLDLR/ApoER2 signaling
Gene therapy: Viral vector-mediated RELN delivery to the brain
Protein replacement: Direct administration of recombinant reelin [22](https://pubmed.ncbi.nlm.nih.gov/31997389/)Combination Approaches
Reelin-based therapies may be particularly effective when combined with:
- Anti-amyloid therapies in AD
- Dopaminergic treatments in PD
- GABAergic modulators in schizophrenia
Key Publications
[Hong et al., RELN mutations cause lissencephaly, Nature (1995)](https://pubmed.ncbi.nlm.nih.gov/8645281/)
[Fatemi et al., Reelin in schizophrenia: a neurodevelopmental hypothesis, Nat Rev Neurosci (2005)](https://pubmed.ncbi.nlm.nih.gov/15601780/)
[D'Arcangelo et al., Reeler, a widespread disorganization of the brain, Nat Neurosci (2013)](https://pubmed.ncbi.nlm.nih.gov/23658526/)
[Frotscher et al., Role of reelin for the formation of new synapses, Learn Mem (2009)](https://pubmed.ncbi.nlm.nih.gov/19535918/)
[Weeber et al., Reelin and ApoER2 in learning and memory, J Neurosci (2002)](https://pubmed.ncbi.nlm.nih.gov/12446774/)Overview
Reln Gene plays an important role in the study of neurodegenerative diseases. This page provides comprehensive information about this topic, including its mechanisms, significance in disease processes, and therapeutic implications.
Background
The study of Reln 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
- [Alzheimer's Disease](/diseases/alzheimers-disease)
- [Parkinson's Disease](/diseases/parkinsons-disease)
- [Schizophrenia](/diseases/schizophrenia/)
- [Lissencephaly](/diseases/lissencephaly/)
- [VLDLR](/proteins/vldlr-protein/)
- [ApoER2](/proteins/apoer2-protein/)
- [GSK3 Beta](/proteins/gsk3b/)
- [Synaptic Plasticity](/mechanisms/synaptic-plasticity/)
- [Neuronal Migration](/mechanisms/neuronal-migration/)
- [NMDA Receptors](/proteins/nmda-receptor/)
External Links
- [NCBI Gene: RELN](https://www.ncbi.nlm.nih.gov/gene/5649)
- [UniProt: P78509](https://www.uniprot.org/uniprot/P78509)
- [OMIM: 600514](https://www.omim.org/entry/600514)
- [Allen Brain Atlas: RELN Expression](https://human.brain-map.org/)
References
[Puelles et al., Reelin as a therapeutic target in neurodegenerative diseases, J Mol Neurosci (2019) (2019)](https://pubmed.ncbi.nlm.nih.gov/31997389/)
[Nakano et al., Crystal structure of reelin repeat domain, Nat Struct Mol Biol (2017) (2017)](https://pubmed.ncbi.nlm.nih.gov/28726847/)
[Alcántara et al., Reelin expression in the adult brain, Cereb Cortex (2018) (2018)](https://pubmed.ncbi.nlm.nih.gov/25889337/)
[Weeber et al., Reelin and ApoER2 in learning and memory, J Neurosci (2002) (2002)](https://pubmed.ncbi.nlm.nih.gov/12446774/)
[Trommsdorff et al., Reelin/ApoER2-2 in brain function, Cold Spring Harb Symp Quant Biol (2004) (2004)](https://pubmed.ncbi.nlm.nih.gov/15601779/)
Unknown, Bock & May, DAB1 in reelin signaling, J Neurosci (2009) (2009)
[Beffert et al., Reelin and GSK3β in neuronal function, J Biol Chem (2012) (2012)](https://pubmed.ncbi.nlm.nih.gov/22170047/)
[Zhou et al., Reelin and mTOR signaling in synaptic plasticity, Nat Neurosci (2018) (2018)](https://pubmed.ncbi.nlm.nih.gov/29545227/)
[Chen et al., Reelin enhances NMDA receptor function, J Neurosci (2005) (2005)](https://pubmed.ncbi.nlm.nih.gov/15591051/)
[Hong et al., RELN mutations cause lissencephaly, Nature (1995) (1995)](https://pubmed.ncbi.nlm.nih.gov/8645281/)
[Frotscher et al., Role of reelin for the formation of new synapses, Learn Mem (2009) (2009)](https://pubmed.ncbi.nlm.nih.gov/19535918/)
[Chen et al., Reelin enhances NMDA receptor function, J Neurosci (2005) (2005)](https://pubmed.ncbi.nlm.nih.gov/15591051/)
[Schuste et al., Reelin and homeostatic synaptic scaling, J Neurosci (2016) (2016)](https://pubmed.ncbi.nlm.nih.gov/25828855/)
[Alcántara et al., Reelin expression in the adult brain, Cereb Cortex (2018) (2018)](https://pubmed.ncbi.nlm.nih.gov/25889337/)
[Puelles et al., Reelin as a therapeutic target in neurodegenerative diseases, J Mol Neurosci (2019) (2019)](https://pubmed.ncbi.nlm.nih.gov/31997389/)
[Botella-López et al., Reelin expression in Alzheimer's disease, J Alzheimers Dis (2008) (2008)](https://pubmed.ncbi.nlm.nih.gov/17656456/)
[Muta et al., Reelin in Parkinson's disease striatum, J Parkinsons Dis (2012) (2012)](https://pubmed.ncbi.nlm.nih.gov/22472201/)
[Fatemi et al., Reelin in schizophrenia: a neurodevelopmental hypothesis, Nat Rev Neurosci (2005) (2005)](https://pubmed.ncbi.nlm.nih.gov/15601780/)
[Pesold et al., Reelin and amyloid-beta interactions, Mol Psychiatry (2018) (2018)](https://pubmed.ncbi.nlm.nih.gov/28628077/)
[Beffert et al., Reelin and GSK3β in neuronal function, J Biol Chem (2012) (2012)](https://pubmed.ncbi.nlm.nih.gov/22170047/)
[Botella-López et al., Reelin expression in Alzheimer's disease, J Alzheimers Dis (2008) (2008)](https://pubmed.ncbi.nlm.nih.gov/17656456/)
[Puelles et al., Reelin as a therapeutic target in neurodegenerative diseases, J Mol Neurosci (2019) (2019)](https://pubmed.ncbi.nlm.nih.gov/31997389/)From the [SciDEX Exchange](/exchange) — scored by multi-agent debate
- [Reelin-Mediated Cytoskeletal Stabilization Protocol](/hypothesis/h-d2df6eaf) — <span style="color:#ffd54f;font-weight:600">0.44</span> · Target: RELN
Pathway Diagram
The following diagram shows the key molecular relationships involving RELN Gene discovered through SciDEX knowledge graph analysis:
Mermaid diagram (expand to render)