4-Phenylbutyrate Rescue in GABRA1 Variants Associated with Developmental Epileptic Encephalopathies: From Cell and...

Area of Science:

• Neuroscience
• Genetics
• Pharmacology

Background:

• Developmental and epileptic encephalopathies (DEEs) are severe neurological disorders often caused by mutations in GABA receptor (GABA_AR) genes.
• Current treatments for DEEs are limited, despite GABA_AR being a key target for antiseizure medications.

Purpose of the Study:

• To investigate the therapeutic potential of 4-phenylbutyrate (PBA) in DEEs associated with GABRA1 gene variants.
• To evaluate PBA's effect on GABA_AR α1 subunit expression, surface trafficking, and function in vitro and in vivo.

Main Methods:

• In silico structural modeling, flow cytometry, patch-clamp electrophysiology, and biochemical assays were employed.
• Studies were conducted using a heterologous HEK293T cell model and GABRA1 variant knockin mice (Gabra1^+/A322D).
• Differential tagging was used to distinguish wildtype (WT) and mutant alleles.

Main Results:

• GABRA1 variants reduced α1 subunit expression and cell surface availability, leading to diminished GABA-evoked currents.
• In silico analysis predicted reduced protein stability for GABRA1 variants.
• PBA treatment increased total and surface expression of both WT and variant α1 subunits, improving GABA_AR function.
• PBA also increased GABA_AR expression in the cortex and thalamus of treated mice.

Conclusions:

• PBA demonstrates significant potential as a treatment for DEEs caused by GABRA1 mutations.
• PBA may act as a common therapeutic agent for various genetic neurological disorders sharing proteostasis pathway defects.
• The drug enhances GABA_AR expression and function, mitigating seizures and improving neurobehavioral outcomes.