Background: Adenosine to inosine (A-to-I) RNA editing is the most frequent editing event in humans. It converts adenosine to inosine in double-stranded RNA regions (in coding and non-coding RNAs) through the action of the adenosine deaminase acting on RNA (ADAR) enzymes. Long non-coding RNAs, particularly abundant in the brain, account for a large fraction of the human transcriptome, and their important regulatory role is becoming progressively evident in both normal and transformed cells. Results: Herein, we present a bioinformatic analysis to generate a comprehensive inosinome picture in long non-coding RNAs (lncRNAs), using an ad hoc index and searching for de novo editing events in the normal brain cortex as well as in glioblastoma, a highly aggressive human brain cancer. We discovered >10,000 new sites and 335 novel lncRNAs that undergo editing, never reported before. We found a generalized downregulation of editing at multiple lncRNA sites in glioblastoma samples when compared to the normal brain cortex. Conclusion: Overall, our study discloses a novel layer of complexity that controls lncRNAs in the brain and brain cancer.

Adenosine-to-inosine (A-to-I) RNA editing, catalyzed by ADAR1 and ADAR2, is an epitranscriptomic mechanism with emerging roles in cardiovascular disease. We investigated ADAR expression, clinical correlates, A-to-I RNA editing signatures, transcriptome and miRNA targetome in thoracic aortic aneurysm (TAA), focusing on Marfan syndrome (MFS). Immunohistochemical analysis of 58 TAA specimens (18 MFS-associated TAA, 19 tricuspid aortic valve-associated TAA (TAV), 21 bicuspid aortic valve-associated TAA (BAV)) showed the highest ADAR1 and ADAR2 in MFS. ADAR2 in vascular smooth muscle cells (vSMCs) correlated positively with aortic diameter across subtypes; ADAR1 inversely correlated with sinotubular junction dimension in MFS. Transcriptomic profiling of MFS-derived vSMC cultures identified 30 differentially expressed genes enriched in immune activation, impaired RTK signaling, and vSMC reprogramming. RNA editing analysis revealed 77 differentially edited sites across 65 genes, predominantly hypoedited in MFS, including four protein-coding recoding events at PPIL3, SLC12A6, CTSB, and VHL. miRNA seed-match analysis of 47 significant 3′UTR sites predicted 458 editing-dependent interactions across 36 genes. Only 14/36 genes showed concordant mRNA changes, suggesting that editing-dependent miRNA retargeting acts primarily at the translational level. These findings establish ADAR enzymes as candidates tissue biomarkers of TAA severity and ADAR1 as the principal driver of epitranscriptomic dysregulation in MFS aortopathy.