A mechanistic classification of GNAO1 mutations links Gβ γ sequestration to hyperkinetic disease and treatment response
Go is the most prevalent G protein subunit in the brain and is critical for signal transduction through G protein-coupled receptors. Mutations in the gene encoding Go (GNAO1) cause a rare neurodevelopmental disorder with involuntary movements (NEDIM) and, in some patients, developmental and epileptic encephalopathy (DEE). Here, we integrate human genetic analysis with cellular assays to define mechanistic classes of GNAO1 mutations and in vivo approaches to evaluate therapeutic strategies. We grouped variants into two functional categories: those predicted to sequester G{beta}{gamma} and those with reduced Go expression and therefore increased G{beta}{gamma} signaling. Analysis of patient data revealed that mutations predicted to impair G{beta}{gamma} release are significantly associated with NEDIM. Using the GNAO1R209H/+ mouse as a model of NEDIM, we evaluated two small molecules: caffeine, a nonselective adenosine receptor antagonist, and gallein, a selective modulator of G{beta}{gamma}-effector interactions. Both compounds significantly reduced hyperlocomotion in the open field test. Whole-cell patch-clamp electrophysiology revealed sex- and cell type-specific hyperexcitability in spiny projection neurons within the dorsolateral striatum of GNAO1R209H/+ mice. Together, these findings implicate dysfunction of dorsolateral striatal pathways in GNAO1-related disorder and suggest that mechanistic understanding of disease variants can guide targeted therapeutic strategies.