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Updated: Jun 3, 2026

Measuring Transcellular Interactions through Protein Aggregation in a Heterologous Cell System
Published on: May 22, 2020
Proteoglycan-specific molecular switch for RPTPσ clustering and neuronal extension
Charlotte H Coles1, Yingjie Shen, Alan P Tenney
1Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford, OX3 7BN, UK.
Heparan and chondroitin sulfate proteoglycans (HSPGs and CSPGs) have opposite effects on sensory neuron extension via receptor protein tyrosine phosphatase sigma (RPTPσ). RPTPσ mediates inhibition by CSPGs and promotion by HSPGs, revealing a novel regulatory mechanism.
Area of Science:
- Neuroscience
- Cell Biology
- Biochemistry
Background:
- Heparan and chondroitin sulfate proteoglycans (HSPGs and CSPGs) modulate cell surface signaling with opposing effects.
- Chondroitin sulfate proteoglycans (CSPGs) are known inhibitors of nerve regeneration through receptor protein tyrosine phosphatase sigma (RPTPσ).
Purpose of the Study:
- To investigate the dual role of RPTPσ in sensory neuron extension.
- To elucidate the mechanism by which RPTPσ mediates opposing effects of HSPGs and CSPGs.
Main Methods:
- Crystallographic analysis of the RPTPσ binding site.
- Biochemical assays measuring RPTPσ ectodomain oligomerization.
- Immunofluorescence microscopy to determine cellular localization of RPTPσ and proteoglycans.
Main Results:
- RPTPσ exhibits conformational plasticity, accommodating both HSPGs and CSPGs with similar affinities.
- Heparan sulfate (HS) induced RPTPσ ectodomain oligomerization, while chondroitin sulfate (CS) inhibited it.
- RPTPσ and HSPGs colocalize on sensory neuron puncta, whereas CSPGs are in the extracellular matrix.
Conclusions:
- RPTPσ acts bimodally in sensory neuron extension, mediating CSPG-induced inhibition and HSPG-induced growth promotion.
- Proteoglycans compete to control RPTPσ oligomerization, thereby exerting opposing effects on neuronal extension.
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