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A High-content Assay for Monitoring AMPA Receptor Trafficking
Published on: January 28, 2019
RAB39B-mediated trafficking of the GluA2-AMPAR subunit controls dendritic spine maturation and intellectual
Maria Lidia Mignogna1, Stefano Musardo2, Giulia Ranieri1
1Neuroscience Division, Unit of molecular genetics of intellectual disability, IRCCS San Raffaele Scientific Institute, Milan, Italy.
Abstract:
Mutations in the RAB39B gene cause X-linked intellectual disability (XLID), comorbid with autism spectrum disorders or early Parkinson's disease. One of the functions of the neuronal small GTPase RAB39B is to drive GluA2/GluA3 α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) maturation and trafficking, determining AMPAR subunit composition at glutamatergic postsynaptic neuronal terminals. Taking advantage of the Rab39b knockout murine model, we show that a lack of RAB39B affects neuronal dendritic spine refinement, prompting a more Ca2+-permeable and excitable synaptic network, which correlates with an immature spine arrangement and behavioural and cognitive alterations in adult mice. The persistence of immature circuits is triggered by increased hypermobility of the spine, which is restored by the Ca2+-permeable AMPAR antagonist NASPM. Together, these data confirm that RAB39B controls AMPAR trafficking, which in turn plays a pivotal role in neuronal dendritic spine remodelling and that targeting Ca2+-permeable AMPARs may highlight future pharmaceutical interventions for RAB39B-associated disease conditions.
Insights
Mutations in the RAB39B gene cause X-linked intellectual disability. Lack of RAB39B impairs neuronal development, leading to cognitive deficits, but targeting specific receptors may offer therapeutic avenues.
Area of Science:
- Neuroscience
- Genetics
- Molecular Biology
Background:
- Mutations in the RAB39B gene are linked to X-linked intellectual disability (XLID), often accompanied by autism spectrum disorders or early Parkinson's disease.
- RAB39B, a neuronal small GTPase, is crucial for the maturation and trafficking of GluA2/GluA3 α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs).
Purpose of the Study:
- To investigate the role of RAB39B in neuronal function and its impact on synaptic plasticity using a Rab39b knockout murine model.
- To explore the potential of targeting calcium-permeable AMPARs as a therapeutic strategy for RAB39B-associated disorders.
Main Methods:
- Utilized a Rab39b knockout mouse model to study the effects of RAB39B deficiency on neuronal structure and function.
- Analyzed neuronal dendritic spine morphology, synaptic excitability, and behavioral/cognitive alterations in adult mice.
- Investigated the efficacy of the calcium-permeable AMPAR antagonist NASPM in restoring normal synaptic function.
Main Results:
- Absence of RAB39B led to impaired dendritic spine refinement, resulting in a more calcium-permeable and excitable synaptic network.
- The study observed immature spine arrangements and associated behavioral and cognitive deficits in adult Rab39b knockout mice.
- Treatment with NASPM restored normal spine morphology by reducing hypermobility, indicating the critical role of calcium-permeable AMPARs.
Conclusions:
- RAB39B is essential for controlling AMPAR trafficking, which is pivotal for neuronal dendritic spine remodeling.
- Dysfunctional RAB39B contributes to immature neuronal circuits and associated cognitive impairments.
- Targeting calcium-permeable AMPARs presents a promising therapeutic avenue for conditions linked to RAB39B mutations.
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