One Ring to Rule Them All: Mitochondrial Circular RNAs Control Mitochondrial Function

Circular RNAs (circRNAs) have emerged as key regulators of a wide variety of biological processes, but the roles of mitochondrial circRNAs are largely unknown. In this issue of Cell, Zhao et al. (2020) reveal that mitochondrial DNA-encoded circRNAs interact with ATP synthase subunit β (ATP5B) to inhibit the output of mitochondrial reactive oxygen species and the activation of liver fibroblasts, which regulate the pathogenesis of liver disease.