Epileptic Encephalopathy GABRB Structural Variants Share Common Gating and Trafficking Defects

Area of Science:

• Neuroscience
• Genetics
• Molecular Biology

Background:

• Variants in the GABRB gene, encoding the GABA-A receptor β subunit, are linked to epileptic encephalopathies (EEs) and neurodevelopmental disorders.
• These disorders, including Dravet and Angelman syndromes, feature early seizures, developmental issues, and cognitive impairments due to GABA-A receptor dysfunction.
• Mutations disrupt the balance of neuronal excitation and inhibition, leading to seizures.

Purpose of the Study:

• To investigate the impact of 13 de novo EE-associated GABRB missense variants on protein stability, flexibility, channel function, and receptor biogenesis.
• To correlate specific mutation locations within the GABRB gene with observed functional and structural changes.
• To establish a framework for predicting disease severity based on variant location and impact on receptor dynamics.

Main Methods:

• Analysis of 13 de novo GABRB missense variants.
• Assessment of protein stability and flexibility.
• Evaluation of GABA-A receptor channel function and biogenesis.
• Mapping of variants to specific functional domains (GABA-binding, coupling zone, pore domain).

Main Results:

• All analyzed GABRB variants significantly altered protein structure, stability, flexibility, and function.
• Mutations in key domains (GABA-binding, coupling zone, pore) affected the β+/α- interface, channel activation, and receptor trafficking.
• The degree of functional alteration varied among the studied variants.

Conclusions:

• GABRB variants impact GABA-A receptor structure and function, contributing to epileptic encephalopathies.
• The specific structural domain affected by a mutation correlates with the extent of receptor dysfunction.
• Assessing variant location and receptor dynamics can help predict disease severity in GABRB-related disorders.