GNAO1-related neurodevelopmental disorders are caused by mutations in the GNAO1 gene encoding the major neuronal G protein, Gαo. GNAO1 encephalopathies manifest in a range of symptoms, including epilepsy, movement disorder, hypotonia, and developmental delay, affecting >400 patients worldwide to date. A growth in the number of diagnosed cases is expected due to the wider availability of whole genome sequencing. One of the most recurrent pathogenic variants causing GNAO1 encephalopathy is an intronic mutation c. 724-8G>A, which results in an in-frame insertion of two amino acid residues Pro-Gln after Thr241: GαoT241N242insPQ. We previously performed in-depth profiling of GαoinsPQ using structural, biochemical, and cellular studies. Compared to the wild-type protein, GαoinsPQ exhibits faster GTP binding and decreased hydrolysis. Importantly, GαoinsPQ is deficient in interacting with regulators of G protein signaling (RGS), GTPase-activating proteins that deactivate Gαo. These defects render GαoinsPQ as a constitutively active mutant loaded with GTP in the G protein signaling. Patients harboring GαoinsPQ variant are in urgent need of novel therapy as they are refractory to available medications. In this study, we performed a high-throughput screening to find molecules that might suppress the constitutive GTP loading by GαoinsPQ. We used a high-diversity chemical library of 54, 080 compounds, identifying a novel compound, N-5- (2-methylpropyl) -1, 3, 4-thiadiazol-2-yl-1H-1, 2, 3-benzotriazole-5-carboxamide, that decreases the GTP binding rate of Gαo, likely acting as a competitive inhibitor with higher selectivity to the pathogenic protein. This small-molecule inhibitor of Gαo opens new opportunities to drug discovery towards Gαo-dependent pathologies.
Larasati et al. (Thu,) studied this question.