SNCA-AS1, antisense transcript to the SNCA gene, regulates alpha-synuclein and synaptic modulation with possible implications in Parkinson’s Disease and aging.

Background/Objectives: SNCA protein product, alpha-synuclein (alpha-syn), is widely renowned for its role in synaptogenesis and implication in both Parkinson’s Disease (PD) and aging, but research efforts are needed to clarify its physiological functions. SNCA-AS1, the antisense transcript to the SNCA gene, has been found up-regulated in PBMCs of patients affected by sporadic PD and its transcriptional modification is implicated in synapse-related genes expression. This work aims to report how SNCA-AS1 affects both synaptic processes and alpha-syn’s expression. Methods: SH-SY5Y cells stably transfected with SNCA-AS1 to overexpress the gene, whereas the knock-down model was performed via CRISPR-dCas9. Real Time-PCR and western blot were used to verify SNCA-AS1’s effects on SNCA’s expression and synapses-related markers. SNCA half-life was assessed via Actinomycin D treatment. Alpha-syn’s expression was evaluated in presence of Cycloheximide. TEM and SEM were performed to analyze morphological aspects of synapses during the neural differentiation. Results: The overexpression of SNCA-AS1 in SH-SY5Y cells upregulates both alpha-syn’s mRNA and protein, whilst its knock-down decreases both targets. This strongly impacts on neurites’ extension and synapses’ morphological ultrastructural aspect, as assessed by SEM and TEM. Through specific molecular signatures SNCA-AS1 causes transcriptional modification in synaptic modulation pathways recapitulating an aging-related decline, as confirmed by RNA-Seq studies. Moreover, we demonstrate that the SNCA-AS1 overexpression reduces the half-life of SNCA mRNA, contrary to what happens in the knock-down model. Lastly, we report that SNCA-AS1 overexpressing cells release alpha-syn in the medium. Conclusions: Our results show that SNCA-AS1 impacts alpha-syn expression, synapses biology and PD-related genes.