PPT1-mediated GABA_ARα1 depalmitoylation maintains inhibitory synaptic homeostasis and cognition

GABA_A receptors (GABA_ARs), essential for inhibitory neurotransmission, are palmitoylated proteins and their depalmitoylation is catalyzed by palmitoyl-protein thioesterase 1 (PPT1). By generating Gabra1^em1 knock-in mice carrying mutations that disrupt the interaction between GABA_ARα1 and PPT1, we found that the mutant mice exhibited impaired learning and memory, whereas the underlying cellular mechanisms remained largely unclear. Molecular analyses showed that heterozygous (HET) Gabra1^em1 mice (Gabra1^em1HET) displayed normal GABA_ARα1 protein expression but persistent hyperpalmitoylation of GABA_ARα1. Electrophysiological recordings demonstrated the decreased neuronal excitability, enhanced inhibitory synaptic transmission and impaired hippocampal long-term potentiation (LTP). Behavioral analyses further revealed deficits in learning, memory and social behavior. The homozygous (HOMO) Gabra1^em1 mice (Gabra1^em1HOMO) exhibited a marked reduction in GABA_ARα1 protein expression, accompanied by enhanced neuronal excitability and excitatory synaptic transmission, but impaired LTP and learning and memory along with a shorten life span. Collectively, these findings indicate that Gabra1^em1 HET mice represent a valuable model for investigating the physiological and pathological roles of protein palmitoylation, as aberrant GABA_ARα1 palmitoylation disrupts neuronal excitability, synaptic plasticity, and cognitive function without altering receptor expression. In contrast, the phenotypes observed in Gabra1^em1 HOMO mice are primarily attributable to the marked reduction in GABA_ARα1 protein expression, which consequently impairs synaptic plasticity and learning and memory. These findings provide new mechanistic insights into the role of protein palmitoylation in neurological disorders and offer a theoretical foundation for the development of precision therapeutic strategies targeting palmitoylation homeostasis.