The polarized structure of axons and dendrites in neuronal cells depends in part on RNA localization. Previous studies have looked at which polyadenylated RNAs are enriched in neuronal projections or at synapses, but less is known about the distribution of non-adenylated RNAs. By physically dissecting projections from cell bodies of primary rat hippocampal neurons and sequencing total RNA, we found an unexpected set of free circular introns with a non-canonical branchpoint enriched in neuronal projections. These introns appear to be tailless lariats that escape debranching. They lack ribosome occupancy, sequence conservation, and known localization signals, and their function, if any, is not known. Nonetheless, their enrichment in projections has important implications for our understanding of the mechanisms by which RNAs reach distal compartments of asymmetric cells.
All raw data (fastq format) and corresponding coverage files (bigwig format) are available at NCBI GEO under accession number GSE129924, and a tarball of supplementary tables and code is at http://eddylab.org/publications.html#Saini19.
Free circular introns with an unusual branchpoint in neuronal projectionsNCBI Gene Expression Omnibus, GSE129924.
- Melissa J Moore
- Sean R Eddy
- Melissa J Moore
- Harleen Saini
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Animal experimentation: This study was performed in strict accordance with the recommendations in the Guide for the Care and Use of Laboratory Animals of the National Institutes of Health. Animals were handled in accordance with protocols approved by the Institutional Animal Careand Use Committees at University of Massachusetts Medical School (docket #A-2245-16) and Harvard University (protocol #10-16-1). All surgery was performed after euthanization, and every effort was made to minimize suffering.
- Benjamin J Blencowe, University of Toronto, Canada
© 2019, Saini et al.
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