Exploring the Molecular Mechanisms Associated with Angelman Syndrome to Develop Clinically Relevant Biomarkers

Abstract

Angelman syndrome is a rare neurogenetic disorder that leads to severe motor deficits, intellectual disability, and seizures. It arises from the loss of expression of the maternal allele of UBE3A in central nervous system neurons; therefore, several therapies are being developed to target central nervous system neurons and restore UBE3A expression. This cell type specificity has made it difficult to evaluate the efficacy of potential therapies without collecting brain tissue. A biomarker reflecting the level of UBE3A expression after treatment would be helpful; however, there are still gaps in knowledge surrounding which pathways are affected in Angelman syndrome. The objective of these studies was to investigate the dysregulated pathways in Angelman syndrome pigs to inform future biomarker studies. The small RNA cargo of extracellular vesicles isolated from blood and cerebrospinal fluid was characterized and compared between Angelman syndrome and WT pigs using RNA sequencing. We identified several known brain-specific and brain-enriched miRNAs contained within these vesicles, suggesting that brain-derived extracellular vesicles and their cargo are detectable in biofluids and may provide a non-invasive way to study the brain in Angelman syndrome. Five small RNAs were dysregulated in extracellular vesicles and will be further investigated for their use as biomarkers in Angelman syndrome. Additionally, mRNA sequencing was used to identify differentially expressed genes in pig tissues to better understand the pathways affected by maternal UBE3A loss. Tubulin genes were identified as dysregulated, suggesting that cytoskeleton dynamics play a role in Angelman syndrome phenotypes. Altogether, these findings lay the groundwork for further investigating the pathways affected by Angelman syndrome and provide evidence for the use of extracellular vesicles as efficacy biomarkers in neurological disorders.