Circular RNA biogenesis is decreased in postmortem cortical gray matter in schizophrenia and may alter the bioavailability of associated miRNA

Journal article

The RNA binding protein FUS participates in several RNA biosynthetic processes; it controls alternative splicing in the nervous system and has recently been demonstrated to be involved in circular RNA (circRNA) biogenesis, a new class of covalently closed RNA molecules arising from a backsplicing event. Notably, alterations of RNA splicing due to FUS mutations have been linked to the pathogenesis of Amyotrophic Lateral Sclerosis (ALS), a neurodegenerative disease that affects upper and lower motoneurons (MNs). In order to investigate the role played by circRNAs in a neuronal system and their potential involvement in ALS, we focused on two circRNAs, circ-31 and circ-16. These circRNAs are conserved between human and mouse, upregulated during neuronal differentiation and highly expressed in MNs, moreover, their expression is affected in FUS-KO MNs and in MNs carrying the P517L FUS mutation. The latter causes a relevant FUS delocalization in the cytoplasm, which is linked to one of the most severe forms of familial ALS where the mutant protein forms cytoplasmic aggregates. In situ Hybridization and immuno-fluorescence approaches showed that circ-31 and circ-16 are localized in the cell body as well as in neuronal processes both in WT and FUS mutant MNs. Oxidative stress on MNs induces stress granule (SG) formation and in mutant cells this was used to mimic pathological ALS conditions where FUS aggregates mostly colocalize with SGs. In this condition, circ-31 is retained in the cell body, and in FUS mutant MNs, tend to co-localize with FUS-positive SG in a preferential manner when compared to circ-16. This suggests an active role of mutant FUS granules in trapping this transcript. Moreover, in order to study circRNA function in physiological MN conditions, we set up and performed RNA pull down experiments in in vitro-derived MNs by using antisense biotinylated oligonucleotides and UV and AMT-psoralen derivative crosslinking, in order to look at protein and RNA interactors respectively. Data from these experiments are currently under analysis. In parallel, we set up a CRISPR/Cas9 approach in order to obtain circRNA KO

Authors: Mahmoudi, E; Fitzsimmons, C; Geaghan, MP; Shannon Weickert, C; Atkins, JR

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Springer Nature [academic journals on nature.com]
• Journal: Neuropsychopharmacology
• Volume: 44
• Issue: 6
• Pages: 1043-1054
• Publication date: 2019-02-20
• DOI: 10.1038/s41386-019-0348-1
• EISSN: 1740-634X
• ISSN: 0893-133X
• Language: English
• Keywords: Gene expression; Gene; Transcriptome; Gene silencing; Circular RNA; Non-coding RNA; Prefrontal cortex; Neuroscience; Genetics; RNA; microRNA; Dorsolateral prefrontal cortex; Biology