FUNCTIONAL CHARACTERIZATION OF A CNS-ENRICHED EXTRANUCLEOLAR SNORNA

Small nucleolar RNAs (snoRNAs) are non-coding RNAs canonically involved in guiding ribosomal RNA modifications within the nucleolus. However, accumulating evidence indicates that some snoRNAs possess the ability to localize beyond the nucleolus, to nuclear and/or cytoplasmic compartments. There, they have been shown to participate in diverse regulatory processes, such as the modulation of alternative splicing and protein translation. Despite these findings, exact functions of these snoRNAs remain poorly understood, particularly in the context of the central nervous system (CNS). Previous data generated in our lab indicate that a subset of snoRNAs are localized to extranucleolar regions in neurons. For this study, we have selected a CNS-enriched and disease associated extranucleolar snoRNA for comprehensive characterization. Using primary mouse neurons as a model, we have validated tissue and cell type specificity via qPCR, which was followed by RNA in situ hybridization to identify the exact sub-cellular localization. Analysis of the subcellular localization revealed distribution across nuclear and cytoplasmic compartments, including dendrites, suggesting diverse regulatory roles. We investigated these roles via RNA-sequencing following knockdown of the snoRNA, which was complemented by functional assays, including dendritic spine quantification and multi-electrode array recordings. Together, our initial results indicate that the candidate snoRNA is involved in regulating neuronal activity, without any impact to synaptic morphology or cell viability. Through further characterization and analysis, we aim to uncover the molecular mechanisms underlying the candidate snoRNA’s localization and functional impact, to contribute new insights into the extranucleolar roles of snoRNAs in the CNS.