Crucial Differences in RNA Editing Between Living and Postmortem Brain Tissue Uncovered in New Study

Researchers from the Icahn School of Medicine at Mount Sinai have uncovered significant differences in RNA editing between living and postmortem brain tissues, shedding new light on brain development and disease mechanisms. Their study, published in Nature Communications, focused on adenosine-to-inosine (A-to-I) editing, a critical RNA modification in the brain.

The team discovered that RNA editing levels were generally higher in postmortem brain tissue compared to living tissue, likely due to postmortem changes such as inflammation and hypoxia. However, they also found hundreds of sites with higher A-to-I editing in living brain tissue, primarily located in synapses and evolutionarily conserved.

Michael Breen, co-senior author, emphasized the importance of these findings: "Until now, the investigation of A-to-I editing and its biological significance in the mammalian brain has been restricted to the analysis of postmortem tissues. By using fresh samples from living individuals, we were able to uncover significant differences in RNA editing activity that previous studies, relying only on postmortem samples, may have overlooked."

The research team utilized the Living Brain Project, which obtains dorsolateral prefrontal cortex tissues from living individuals during neurosurgical procedures. They compared these samples with postmortem tissues matched for demographic and clinical variables. The team investigated multiple genomic data types from the Living Brain Project, including bulk tissue RNA sampling, single-nuclei RNA sequencing, and whole-genome sequencing. 

Alexander W. Charney, co-senior author, highlighted the study's implications: "Utilizing fresh brain tissue from living human donors provided us the opportunity to investigate the brain without the confounds inherent to postmortem tissue analysis. In doing so, we revealed more accurate insights into the prevalence and roles of A-to-I editing in the human brain."

The research team will further analyze the RNA editing data to understand its implications better and to identify potential therapeutic targets for Parkinson’s disease. They are also expanding the research to include emerging work from this cohort that focuses on gene expression, proteomics, and multi-omics of the living brain.