In an RNA-seq-based study, investigators at the University of California, San Francisco, have found that the human genome encodes far more long, intergenic noncoding RNAs (lincRNAs) than were previously known.
And while lincRNAs had largely been considered genomic “junk”—transcriptional noise—the scientists present in PLOS Genetics new evidence to suggest some may have functional consequences.
“We found that the lincRNAs we identified have many characteristics that are inconsistent with noise, including specific regulation of their expression, the presence of conserved sequence and evidence for regulated processing,” UCSF’s Michael McManus, Ph.D., and his colleagues write. “Furthermore, these lincRNAs are strongly enriched with intergenic sequences that were previously known to be functional in human traits and diseases.”
Dr. McManus et al., studied a large set of RNA-seq data covering an array of tissue types and performed de novo transcriptome assembly.
Overall, the investigators identified tens of thousands of putative lincRNAs expressed at a level of at least one copy per cell. Finding many more lincRNAs than they had anticipated, the researchers write, actually helps “to resolve the discrepancy between the vast amount of observed intergenic transcription and the limited number of previously known lincRNAs.”
“Now that we realize that all these RNA molecules exist and have identified them, the struggle is to understand which are going to have a function that is important,” Dr. McManus said in a statement. “It may take decades to determine this.”
“Pervasive transcription of the human genome produces thousands of previously unidentified long intergenic noncoding RNAs” appeared in PLOS Genetics June 20.