Genome-wide map of spliced-leader-led trans-splice sites in Oikopleura dioica

GEO series: GSE50849

Experiment type: Expression profiling by high throughput sequencing

Summary: Polycistronic mRNAs transcribed from operons are resolved via the trans-splicing of a spliced leader (SL) RNA. The SL is also frequently trans-spliced to monocistronic transcripts. Using a modified cap analysis of gene expression (CAGE) protocol we mapped sites of SL trans-splicing genome-wide in the marine chordate Oikopleura dioica and find evidence for proposed functions of SL-trans-splicing. A recent hypothesis postulates that operons facilitate recovery from growth arrested states in metazoans. We examined the expression dynamics of operons across the life-cycle of the animal and during growth arrest recovery. We show that operons do not facilitate recovery from growth arrest in O. dioica. We find that operons are enriched in the germline and that trans-spliced transcripts are predominantly maternal., Interestingly, there is a TOP-like motif in the SL sequence, and trans-splicing in TOP mRNAs, indicating that trans-spliced mRNAs are targets for nutrient-dependent translational control in O. dioica.

Overall design: Total RNA from a number of stages across development were pooled and used in a modified DeepCAGE protocol. A custom designed spliced-leader primer (using the SL exon) was used in the 2nd strand synthesis step.

CitationG.B. Danks, M. Raasholm, C. Campsteijn, A.M. Long, J.R. Manak, B. Lenhard, and E.M. Thompson. Trans-splicing and operons in metazoans: Translational control in maternally regulated development and recovery from growth arrest. Molecular Biology and Evolution, 32(3), 2015.