Genome-Wide Perturbations of Alu Expression and Alu-Associated Post-Transcriptional Regulations Find a Uniqueness in Oligodendroglioma

Abstract BackgroundAlu is a primate-specific repeat element in the human genome and has been increasingly appreciated as a regulatory element in many biological processes. But the role of Alu has not been studied comprehensively in brain tumor because an evolutionary perspective has been the subject of little research in brain tumor. We aim to investigate the relevance of Alu to the gliomagenesis.MethodsUsing a total of 41 pairs of neurotypicial brain tissue samples and samples of diverse gliomas, we performed strand-specific RNA-seq and analyzed two Alu-associated post-transcriptional regulations, A-to-I editing and circular RNAs, and Alu expression in a genome-wide way. ResultsWe found that while both A-to-I editing and circular RNA are decreased overall in gliomas, grade 2 oligodendrogliomas do not show this same pattern of global changes. Instead, in comparison with other gliomas, oligodendrogliomas showed a higher proportion of perturbed Alu RNA. Adenosine deaminase acting on RNA 2 (ADAR2) was down-regulated in gliomas other than grade 2 oligodendrogliomas, contributing to the observed Alu-associated perturbation. ConclusionsOur results demonstrate that Alu is associated with glioma development and grade 2 oligodendroglioma exhibits a unique pattern of Alu-associated post-transcriptional regulations, which provides an insight to gliomagenesis from the perspective of an evolutionary genetic element.