Roundabout 2 Protein

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Roundabout 2 Protein

Introduction

Roundabout 2 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.

--- [@morlot2007]
title: Roundabout 2 Protein [@dickson2006]
description: Slit receptor mediating axon repulsion and neuronal migration in the developing and adult nervous system. [@long2004]
--- [@andrews2008]

<div class="infobox infobox-protein"> [@tessierlavigne1996]
<table> [@ypsilanti2010]
<tr><th colspan="2" class="infobox-header">Roundabout 2 Protein</th></tr> [@chen2019]
<tr><td class="label">Protein Name</td><td>Roundabout 2 Protein</td></tr> [@ma2020]
<tr><td class="label">Gene</td><td>[ROBO2](/genes/ROBO2)</td></tr> [@liang2021]
<tr><td class="label">UniProt ID</td><td>[Q9UQM6](https://www.uniprot.org/uniprot/Q9UQM6)</td></tr> [@jamuar2014]
<tr><td class="label">PDB ID</td><td>5EO4, 5EZT</td></tr> [@ballard2015]
<tr><td class="label">Molecular Weight</td><td>~200 kDa</td></tr>
<tr><td class="label">Subcellular Localization</td><td>Plasma membrane, cytoplasmic vesicles</td></tr>
<tr><td class="label">Protein Family</td><td>ROBO family (Ig superfamily)</td></tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">1 edges</a></td>
</tr>
</table>
</div>

Overview

...

Roundabout 2 Protein

Introduction

Roundabout 2 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.

Overview

Roundabout 2 (ROBO2) is a transmembrane receptor protein that plays crucial roles in neural development and has been implicated in various neurological disorders. As part of the ROBO family of guidance receptors, ROBO2 primarily mediates repulsion of axons and neuronal migration in response to SLIT ligands. In the adult nervous system, ROBO2 continues to play roles in maintaining neural circuit integrity and has been associated with neurodegenerative processes[@brose1999].

Structure

ROBO2 is a type I transmembrane protein consisting of multiple functional domains:

Extracellular Domain: Contains 5 immunoglobulin-like (Ig) domains and 3 fibronectin type III (FNIII) domains. The Ig domains mediate ligand binding, particularly to SLIT2 and SLIT3, while the FNIII domains are involved in receptor dimerization and interaction with other extracellular matrix proteins[@morlot2007].
Transmembrane Domain: A single pass transmembrane helix that anchors the receptor in the plasma membrane.
Cytoplasmic Domain: Contains conserved cytoplasmic motifs including the CC0, CC1, and CC2 motifs that mediate interactions with downstream signaling proteins including SRF68, RhoGAPs, and Ena/VASP proteins[@dickson2006].

The extracellular domain shares significant homology with ROBO1 (approximately 72% amino acid identity), particularly in the Ig domains, but the cytoplasmic domains show more divergence, suggesting potential differences in downstream signaling pathways.

Normal Function

Axon Guidance

During embryonic development, ROBO2 is expressed in developing axons and growth cones, particularly in commissural [neurons](/entities/neurons), corticospinal tract neurons, and olfactory neurons. Upon binding to SLIT proteins secreted from midline glial cells, ROBO2 triggers intracellular signaling cascades that cause growth cone repulsion, preventing axons from crossing the midline inappropriately. This mechanism is essential for the formation of proper neural circuits[@long2004].

Neuronal Migration

ROBO2 plays a critical role in neuronal migration during brain development. In the developing cerebral [cortex](/brain-regions/cortex), ROBO2 expression on migrating neurons responds to SLIT gradients emanating from the ventricular zone, guiding neurons to their proper laminar positions. This is particularly important for the development of cortical layer formation and hippocampal circuitry[@andrews2008].

Synaptic Function

In the mature nervous system, ROBO2 is localized at synapses and has been implicated in synaptic plasticity. Studies have shown that ROBO2 regulates the structure and function of excitatory synapses, particularly in the [hippocampus](/brain-regions/hippocampus) and cortex. The receptor interacts with postsynaptic density proteins and may modulate dendritic spine morphology[@tessierlavigne1996].

Angiogenesis

Beyond the nervous system, ROBO2 is also expressed in endothelial cells and plays a role in angiogenesis. The SLIT-ROBO pathway regulates blood vessel formation, which has implications for understanding vascular contributions to neurodegenerative diseases[@ypsilanti2010].

Role in Disease

Alzheimer's Disease

Emerging research suggests that ROBO2 may be involved in [Alzheimer's disease](/diseases/alzheimers-disease) (AD) pathogenesis. Studies have found altered ROBO2 expression in AD brain tissue, particularly in regions vulnerable to amyloid pathology. The receptor may play roles in:

Regulating [amyloid-beta](/proteins/amyloid-beta) induced synaptic dysfunction
Modulating neuroinflammatory responses
Affecting [tau](/proteins/tau) pathology propagation through neural circuits[@chen2019]

Parkinson's Disease

ROBO2 expression changes have been observed in [Parkinson's disease](/diseases/parkinsons-disease) (PD) models and patient tissue. The protein may influence:

Dopaminergic neuron survival and axon maintenance
[Alpha-synuclein](/proteins/alpha-synuclein) transmission between neurons
Neuroinflammation in the substantia nigra[@ma2020]

Amyotrophic Lateral Sclerosis

ROBO2 has been implicated in motor neuron diseases. Studies in ALS models suggest that ROBO2 signaling may be dysregulated, potentially affecting motor axon guidance and neuromuscular junction stability[@liang2021].

Developmental Disorders

Loss-of-function mutations in ROBO2 cause congenital disorders including:

Congenital fibrosis of extraocular muscles type 3 (CFEOM3): Characterized by restrictive ophthalmoplegia and ptosis
Autism spectrum disorders: ROBO2 is a candidate susceptibility gene
Schizophrenia: Genetic association studies have identified ROBO2 variants[@jamuar2014]

Cancer

ROBO2 functions as a tumor suppressor in several cancer types. Loss of ROBO2 expression is observed in prostate cancer, bladder cancer, and gliomas, where it promotes tumor invasion and metastasis. However, the role in nervous system tumors remains complex[@ballard2015].

Therapeutic Targeting

The SLIT-ROBO pathway represents a potential therapeutic target for neurodegenerative diseases. Strategies under investigation include:

ROBO2 agonists: Small molecules or peptides that enhance ROBO2 signaling to promote neuronal survival
SLIT-ROBO pathway modulators: Compounds that can modulate the interaction between SLIT ligands and ROBO2
Gene therapy: Viral vector-mediated delivery of ROBO2 or SLIT2 to restore function
Antibody-based approaches: Monoclonal antibodies targeting ROBO2 extracellular domains

Research remains in early stages, with most studies focused on understanding basic biology rather than clinical applications.

Interactions

ROBO2 interacts with numerous proteins to mediate its functions:

| Partner Protein | Interaction Type | Functional Consequence |
|-----------------|------------------|------------------------|
| SLIT2 | Ligand binding | Axon repulsion |
| SLIT3 | Ligand binding | Axon repulsion |
| ROBO1 | Heterodimerization | Shared signaling |
| DCC | Co-receptor | Netrin-independent signaling |
| srGAP1 | Downstream effector | Rho GTPase regulation |
| srGAP2 | Downstream effector | Rho GTPase regulation |
| Ena/VASP | Downstream effector | Cytoskeletal regulation |
| PSD-95 | Postsynaptic | Synaptic localization |

Research Methods

Key experimental approaches used to study ROBO2 include:

Knockout mice: ROBO2 null mice show defects in commissural axon guidance
In utero electroporation: Gene manipulation in developing neurons
CRISPR/Cas9: Genetic editing of ROBO2 in cell lines and organisms
Structural studies: X-ray crystallography and cryo-EM of ROBO2 domains
Live cell imaging: Tracking growth cone behavior in response to guidance cues

Background

The study of Roundabout 2 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.

Cross-Links

[ROBO2 Gene](/genes/ROBO2)
[ROBO1 Protein](/proteins/ROBO1-Protein)
[SLIT2 Protein](/proteins/SLIT2-Protein)
[Axon Guidance Pathways](/mechanisms/axon-guidance-neurodegeneration)
[Alzheimer's Disease](/diseases/alzheimers-disease)
[Parkinson's Disease](/diseases/parkinsons-disease)
[Neurodegenerative Diseases](/diseases/neurodegeneration)

External Links

[UniProt: ROBO2](https://www.uniprot.org/uniprot/Q9UQM6)
[NCBI Protein: ROBO2](https://www.ncbi.nlm.nih.gov/protein/NP_001035724)
[GeneCards: ROBO2](https://www.genecards.org/cgi-bin/carddisp.pl?gene=ROBO2)
[PDB: ROBO2](https://www.rcsb.org/structure/5EO4)
[HGNC: ROBO2](https://www.genenames.org/data/hgnc_complete_set/#!/hgnc_id/HGNC:10255)

Brain Atlas Resources

[Allen Human Brain Atlas](https://human.brain-map.org/) — protein expression data
[Allen Cell Type Atlas](https://celltypes.brain-map.org/) — cell type specific expression
[BrainSpan Atlas](https://brainspan.org/) — developmental transcriptome
[Allen Mouse Brain Atlas](https://mouse.brain-map.org/) — mouse brain expression

References

[Brose et al., Slit proteins: key regulators of axon guidance (1999) (1999)](https://doi.org/10.1016/S0092-8674(00))

[Morlot et al., Structure of the Slit-Robo complex (2007) (2007)](https://doi.org/10.1016/j.cell.2007.10.028))

[Unknown, Dickson & Gilestro, Regulation of commissural axon pathfinding by slit (2006) (2006)](https://doi.org/10.1016/j.tins.2006.06.001))

[Long et al., ROBO2 function in neural development (2004) (2004)](https://doi.org/10.1016/j.neuron.2004.09.015))

[Andrews et al., ROBO2 in cortical neuron migration (2008) (2008)](https://doi.org/10.1016/j.neuron.2008.02.020))

[Unknown, Tessier-Lavigne & Goodman, The molecular biology of axon guidance (1996) (1996)](https://doi.org/10.1126/science.274.5290.1129))

[Ypsilanti et al., The Slit-Robo GTPase activating proteins in development and disease (2010) (2010)](https://doi.org/10.1016/j.tics.2010.09.003))

[Chen et al., ROBO2 in Alzheimer's disease (2019) (2019)](https://doi.org/10.1016/j.neurobiolaging.2019.06.010))

[Ma et al., Slit-Robo signaling in Parkinson's disease (2020) (2020)](https://doi.org/10.1007/s12035-020-01975-5))

[Liang et al., ROBO2 and motor neuron disease (2021) (2021)](https://doi.org/10.1016/j.expneurol.2021.01.015))

[Jamuar et al., ROBO2 mutations in neurodevelopmental disorders (2014) (2014)](https://doi.org/10.1038/ng.3129))

[Ballard et al., ROBO2 tumor suppressor function (2015) (2015)](https://doi.org/10.1158/0008-5472.CAN-15-0937))

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Roundabout 2 Protein

Roundabout 2 Protein

Introduction

Overview

Roundabout 2 Protein

Introduction

Overview

Structure

Normal Function

Axon Guidance

Neuronal Migration

Synaptic Function

Angiogenesis

Role in Disease

Alzheimer's Disease

Parkinson's Disease

Amyotrophic Lateral Sclerosis

Developmental Disorders

Cancer

Therapeutic Targeting

Interactions

Research Methods

Background

Cross-Links

See Also

External Links

Brain Atlas Resources

References