Figure 1.

Circular RNAs Can Collectively Modulate Innate Immune Responses

A pre-mRNA can be spliced to generate a linear mRNA or a circular RNA. In normal uninfected cells, many circular RNAs act as a group to bind and inhibit activity of the PKR kinase (1). Upon viral infection (2), pathogenic double-stranded RNAs (dsRNAs) can be produced that lead to activation of RNase L (3), which endonucleolytically cleaves circular RNAs. This releases PKR (4) which can then bind the pathogenic dsRNAs and become activated (5) to inhibit the viral infection (6).