Aripiprazole offsets mutant ATXN3-induced motor dysfunction by targeting dopamine D2 and serotonin 1A and 2A receptors in C. elegans

The atypical antipsychotic aripiprazole is a Food and Drug Administration-approved drug for the treatment of psychotic, mood, and other psychiatric disorders. Previous drug discovery efforts pinpointed aripiprazole as an effective suppressor of Machado–Joseph disease (MJD) pathogenesis, as its administration resulted in a reduced abundance and aggregation of mutant Ataxin-3 (ATXN3) proteins. Dopamine partial agonism and functional selectivity have been proposed as the main pharmacological mechanism of action of aripiprazole in the treatment of psychosis; however, this mechanism remains to be determined in the context of MJD. Here, we focus on confirming the efficacy of aripiprazole to reduce motor dysfunction in vivo, using a Caenorhabditis elegans (C. elegans) model of MJD, and on unveiling the drug targets required for its positive action against mutant ATXN3 pathogenesis. We employed pharmacogenetics and pharmacological approaches to identify which dopamine and serotonin receptors are critical for aripiprazole-mediated improvements in motor function. We demonstrated that dopamine D2-like and serotonin 5-HT1A and 5-HT2A receptors play important roles in this process. Our findings strengthen the relevance of dopaminergic and serotoninergic signaling modulation against mutant ATXN3-mediated pathogenesis. The identification of aripiprazole’s cellular targets, relevant for MJD and perhaps other neurodegenerative diseases, may pave the way for prospective drug discovery and development campaigns aiming to improve the features of this prototypical compound and reduce side effects not negligible in the case of aripiprazole.This work was funded by FEDER through the Competitiveness Internationalization Operational Program (POCI) and by National funds through the Foundation for Science and Technology (FCT), under the scope of the project POCI-01-0145-FEDER-0 31987, NORTE-01-0145-FEDER-000013, and NORTE-01-0145-FEDER-000023, supported by the Northern Portugal Regional Operational Program (NORTE 2020), under the Portugal 2020 Partnership Agreement through the European Regional Development Fund (ERDF) and by ICVS Scientific Microscopy Platform, member of the national infrastructure PPBI—Portuguese Platform of Bioimaging (PPBI-POCI-01-0145-FEDER-022122; by National funds through the Foundation for Science and Technology (FCT)—project UIDB/50026/2020 and UIDP/50026/2020). Additionally, this project was supported by the National Ataxia Foundation (NAF). A.J., J.P.-S., D.V.-C., and J.D.S. were supported by the FCT individual fellowships SFRH/BD/76613/2011, PD/BDE/127834/2016, SFRH/BD/147826/2019, and PD/BD/128074/2016, respectively