Cajal-Retzius Cells
<table class="infobox infobox-celltype">
<tr>
<th class="infobox-header" colspan="2">Cajal-Retzius Cells</th>
</tr>
<tr>
<td class="label">Allen Atlas ID</td>
<td><a href="https://portal.brain-map.org/atlases-and-data/rnaseq" target="_blank">CS202210140_3301</a></td>
</tr>
<tr>
<td class="label">Lineage</td>
<td>Neuron > Transient > Cajal-Retzius</td>
</tr>
<tr>
<td class="label">Markers</td>
<td>RELN, CALB1, LHX5, NRP1, ASTN1</td>
</tr>
<tr>
<td class="label">Brain Regions</td>
<td>Cortical marginal zone (Layer 1)</td>
</tr>
<tr>
<td class="label">Disease Vulnerability</td>
<td>Lissencephaly, Schizophrenia</td>
</tr>
</table>
Cajal-Retzius Cells
Introduction
Cajal Retzius Cells 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
Cajal-Retzius Cells are a critical transient population of neurons that play essential roles in cortical development. Named after Santiago Ramón y Cajal and Gustaf Retzius, who first described these cells in the late 19th century, they are among the first neurons generated in the developing cerebral cortex.
...Cajal-Retzius Cells
<table class="infobox infobox-celltype">
<tr>
<th class="infobox-header" colspan="2">Cajal-Retzius Cells</th>
</tr>
<tr>
<td class="label">Allen Atlas ID</td>
<td><a href="https://portal.brain-map.org/atlases-and-data/rnaseq" target="_blank">CS202210140_3301</a></td>
</tr>
<tr>
<td class="label">Lineage</td>
<td>Neuron > Transient > Cajal-Retzius</td>
</tr>
<tr>
<td class="label">Markers</td>
<td>RELN, CALB1, LHX5, NRP1, ASTN1</td>
</tr>
<tr>
<td class="label">Brain Regions</td>
<td>Cortical marginal zone (Layer 1)</td>
</tr>
<tr>
<td class="label">Disease Vulnerability</td>
<td>Lissencephaly, Schizophrenia</td>
</tr>
</table>
Cajal-Retzius Cells
Introduction
Cajal Retzius Cells 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
Cajal-Retzius Cells are a critical transient population of neurons that play essential roles in cortical development. Named after Santiago Ramón y Cajal and Gustaf Retzius, who first described these cells in the late 19th century, they are among the first neurons generated in the developing cerebral cortex.
Cajal-Retzius Cells are classified within the Neuron > Transient > Cajal-Retzius lineage and are primarily located in the cortical marginal zone (Layer 1). These cells are transient - they are abundant during embryonic and early postnatal development but largely disappear in adulthood through programmed cell death.
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Multi-Taxonomy Classification
Taxonomy Database Cross-References
| Taxonomy | ID | Name / Label |
|----------|----|---------------|
| Cell Ontology (CL) | [CL:0000695](https://www.ebi.ac.uk/ols4/ontologies/cl/classes/http%253A%252F%252Fpurl.obolibrary.org%252Fobo%252FCL_0000695) | Cajal-Retzius cell |
PanglaoDB Marker Cross-References
External Database Links
- [Cell Ontology (CL:0000695)](https://www.ebi.ac.uk/ols4/ontologies/cl/classes/http%253A%252F%252Fpurl.obolibrary.org%252Fobo%252FCL_0000695)
- [OBO Foundry (CL:0000695)](http://purl.obolibrary.org/obo/CL_0000695)
- [Allen Brain Cell Atlas](https://portal.brain-map.org/atlases-and-data/bkp/abc-atlas)
- [CellxGene Census](https://cellxgene.cziscience.com/)
- [Human Cell Atlas](https://www.humancellatlas.org/)
- [PanglaoDB](https://panglaodb.se/)
Taxonomy & Classification
| Database | ID | Name | Confidence |
|----------|----|------|------------|
| Cell Ontology | [CL:0000695](https://www.ebi.ac.uk/ols4/ontologies/cl/classes/http%253A%252F%252Fpurl.obolibrary.org%252Fobo%252FCL_0000695) | Cajal-Retzius cell | Exact |
PanglaoDB Marker Cross-References
External Database Links
- [Cell Ontology (CL:0000695)](https://www.ebi.ac.uk/ols4/ontologies/cl/classes/http%253A%252F%252Fpurl.obolibrary.org%252Fobo%252FCL_0000695)
- [OBO Foundry (CL:0000695)](http://purl.obolibrary.org/obo/CL_0000695)
- [Allen Brain Cell Atlas](https://portal.brain-map.org/atlases-and-data/bkp/abc-atlas)
- [CellxGene Census](https://cellxgene.cziscience.com/)
- [PanglaoDB](https://panglaodb.se/)
Historical Discovery
Santiago Ramón y Cajal (1891)
Cajal first described these cells in 1891 as "células de casquete" (cap cells) based on their distinctive morphology with horizontally oriented axons in the marginal zone.
Gustaf Retzius (1894)
Retzius provided detailed anatomical descriptions, coining the term "Cajal-Retzius cells" that persists today.
Morphology and Cellular Properties
Morphological Features
- Somatic Location: Horizontally oriented cell bodies in layer 1, just beneath the pial surface
- Dendritic Arborization: Vertically oriented dendrites extending toward the pial surface
- Axonal Projection: Horizontally running axons that travel long distances within layer 1, forming extensive axonal plexuses
- Characteristic Axon Initial Segment: Thick, vertically oriented axon initial segment
Electrophysiological Properties
Cajal-Retzius cells exhibit unique firing properties:
- Depolarized Resting Membrane Potential: ~-50 mV
- High Input Resistance: 300-500 MΩ
- Sodium-Dependent Action Potentials: Generate overshooting action potentials
- Spontaneous Firing: Many fire spontaneously in the embryonic cortex
- Depolarizing Responses: Typically respond to excitatory inputs with depolarization
Molecular Markers and Transcriptomic Profile
Primary Markers
- RELN (Reelin): The defining secreted protein; crucial for cortical lamination
- CALB1 (Calretinin): Calcium-binding protein
- LHX5: Lim homeobox transcription factor
- NRP1 (Neuropilin-1): Semaphorin receptor
- ASTN1 (Astrin 1): Neuronal migration protein
Transcriptomic Signature
Single-cell RNA sequencing from the [Allen Cell Type Atlas](https://portal.brain-map.org/atlases-and-data/rnaseq) reveals:
- High expression of Reelin signaling components
- Distinct transcription factor profile (LHX5, FOXP2)
- Extracellular matrix remodeling genes
- Cell adhesion molecules
Developmental Functions
Cajal-Retzius cells serve critical functions during cortical development:
Cortical Lamination
The primary function of Cajal-Retzius cells is to secrete Reelin, which is essential for:
Neuronal Positioning: Guide postmitotic neurons to their correct laminar position
Pyramidal Cell Migration: Control radial migration of pyramidal neuron precursors
Inverted Cortical Architecture: Reelin deficiency leads to inverted cortical layers (lissencephaly)Synaptogenesis
- Provide scaffold for synaptic contacts
- Express synaptic adhesion molecules
- Guide thalamocortical axon targeting
Neuronal Survival
- Secrete neurotrophic factors
- Support adjacent neuron survival
- Regulate programmed cell death
Normal Function in the Adult Brain
While Cajal-Retzius cells are predominantly transient, residual populations persist in the adult brain:
Layer 1 Interneurons
- Small population remains in adult layer 1
- Function as modulatory interneurons
- May contribute to cortical processing
Role in Plasticity
- Express activity-dependent genes
- Potential role in adult plasticity
- Contribute to Reelin signaling maintenance
Vulnerability in Disease
Lissencephaly
Causal Relationship: Loss of Cajal-Retzius cell function directly causes lissencephaly:
RELN Mutations: Loss of Reelin secretion
RELN Gene Deletions: Chromosomal abnormalities
DCX Mutations: Affect Cajal-Retzius cell migrationPathological Features
- Absent or reduced cortical gyration (smooth brain)
- Thick, four-layered cortex
- Neuronal migration defects
- Severe intellectual disability
Schizophrenia
Evidence for Involvement
- Postmortem studies show reduced Reelin expression in schizophrenia
- Genetic associations with RELN polymorphisms
- Altered Cajal-Retzius cell numbers in prefrontal cortex
Proposed Mechanisms
Reelin Deficiency: Reduced Reelin affects neuronal positioning
Synaptic Abnormalities: Impaired synapse formation
Network Dysconnectivity: Altered cortical circuitryOther Neurological Conditions
- Epilepsy: Altered Reelin signaling
- Autism Spectrum Disorder: Reelin polymorphisms associated
- Bipolar Disorder: Reelin expression changes
Reelin Signaling Pathway
The Reelin signaling cascade is essential for cortical lamination:
Reelin Secretion: Cajal-Retzius cells secrete Reelin into the extracellular matrix
Receptor Binding: Reelin binds to ApoER2 and VLDLR on target neurons
Dab1 Phosphorylation: Intracellular adaptor protein Dab1 is phosphorylated
Downstream Signaling: Activates PI3K/Akt and MAPK/ERK pathways
Cellular Effects: Controls cytoskeletal organization, migration, and synaptic plasticityReeler Mouse
The reeler mouse (RELN-deficient) provides a model system:
- Inverted cortical layers
- Cerebellar hypoplasia
- Motor coordination deficits
- Cognitive impairments
Therapeutic Implications
Drug Targets
- Reelin agonists: Small molecules enhancing Reelin signaling
- HDAC inhibitors: Increase RELN expression
- ApoER2/VLDLR modulators: Enhance downstream signaling
Gene Therapy
- RELN gene delivery
- Cell replacement therapy
- Exosome-mediated Reelin delivery
Research Applications
- Reeler Mouse Model: Study cortical development
- Organoid Systems: Model human cortical lamination
- CRISPR Screens: Identify Reelin signaling components
Key Publications
[Cajal-Retzius cells: embryonic organizers of the cortex](https://doi.org/10.1038/s41583-020-0335-5). Nat Rev Neurosci, 2020.
[Reelin in cortical development and disease](https://doi.org/10.1016/j.neuropharm.2020.108214). Neuropharmacology, 2020.
[Molecular anatomy of the developing cerebral cortex](https://doi.org/10.1038/s41586-020-1972-0). Nature, 2020.
External Links
- Allen Cell Type Atlas: [https://portal.brain-map.org/atlases-and-data/rnaseq](https://portal.brain-map.org/atlases-and-data/rnaseq)
- Allen Human Brain Atlas: [https://human.brain-map.org/](https://human.brain-map.org/)
- Reeler Mouse: [Jackson Laboratory](https://www.jax.org/strain:000235)
- [Cell Types Index](/cell-types) RELN Gene
- Reelin Signaling Pathway
- Cortical Development
- [Lissencephaly](/diseases/lissencephaly)
- S- [Genes Index](/genes)Genes In- [Mechanisms Index](/mechanisms)- Mechanisms Index
- --
Background
The study of Cajal Retzius Cells 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.