IN VITRO ASSESSMENT OF D2 DOPAMINE RECEPTOR-INDUCED MICROEXON 8A INCLUSION IN LSD1: AN EPIGENETIC FATE UNDER DOPAMINE CONTROL

Lysine-specific demethylase 1 (LSD1) is a key epigenetic enzyme involved in neuroplastic adaptation and modulates gene expression in response to environmental stimuli. LSD1 exists in distinct isoforms with opposing transcriptional functions, generated by alternative splicing. The ubiquitous isoform (uLSD1) functions as a transcriptional repressor by demethylating the permissive epigenetic marks H3K4me1/2. In contrast, neuroLSD1—an isoform exclusively expressed in neurons via the inclusion of microexon 8a (Ex8a)—acquires transcriptional activating properties by demethylating the repressive marks H3K9me1/2 and H4K20me1/2. Our preliminary results suggest that dopaminergic signaling directly modulates LSD1 splicing; specifically, the dopamine D2 receptor (D2R) agonist Quinpirole increases neuroLSD1 transcripts in the Nucleus Accumbens (NAc) of rats in acute exposure and reduces them after repeated exposure in the NAc and mesencephalon. On the other hand, mice lacking D2R in dopaminergic neurons show decreased neuroLSD1 expression in the mesencephalon. These findings suggest that Ex8a inclusion responds to D2R stimulation. The expression of LSD1 isoforms depends on the splicing factors NOVA1 and SRRM4, which are known to be responsive to neuronal depolarization. Here, we investigate the direct effect of D2R stimulation on LSD1 splicing in vitro. Using a minigene reporter system, we evaluate the impact of the selective D2R agonist Quinpirole on splicing factor activity and the subsequent inclusion of Ex8a.