Figure 6. Schematic model of circular and linear RNAs in proliferating and non-proliferating cells.

Assumption: Circular and linear RNAs are synthesized by specific splice events in a gene (cell type and condition) dependent ratio. While linear RNAs are in a steady state of regulated synthesis and degradation, circular RNAs are much more stable. During proliferation both RNA species are evenly distributed to daughter cells. The steady state level of linear transcripts is accurately controlled and maintained by active transcription and degradation also leading to new expression of circular RNAs and resulting in constant ratios of circular to linear isoforms (lower panel). In contrast, in non-proliferating cells stable circular RNAs accumulate whereas linear transcripts are in a regulated steady state of transcription and degradation (upper panel).