Proteostasis regulation of GABA_A receptors in neuronal function and disease

The γ-aminobutyric acid type A receptors (GABA_ARs) are ligand-gated anion channels that mediate fast inhibitory neurotransmission in the mammalian central nervous system. GABA_ARs form heteropentameric assemblies comprising two α1, two β2, and one γ2 subunits as the most common subtype in mammalian brains. Proteostasis regulation of GABA_ARs involves subunit folding within the endoplasmic reticulum, assembling into heteropentamers, receptor trafficking to the cell surface, and degradation of terminally misfolded subunits. As GABA_ARs are surface proteins, their trafficking to the plasma membrane is critical for proper receptor function. Thus, variants in the genes encoding GABA_ARs that disrupt proteostasis result in various neurodevelopmental disorders, ranging from intellectual disability to idiopathic generalized epilepsy. This review summarizes recent progress about how the proteostasis network regulates protein folding, assembly, degradation, trafficking, and synaptic clustering of GABA_ARs. Additionally, emerging pharmacological approaches that restore proteostasis of pathogenic GABA_AR variants are presented, providing a promising strategy to treat related neurological diseases.