Small mitochondrial-targeted RNAs modulate endogenous mitochondrial protein expression in vivo

•We developed a novel series of mtTRES vectors that express small RNAs in vivo.•Chimeric mitochondrial-targeted RNAs function as translational inhibitors (TLIs).•We developed mtTRES TLI constructs that modulate expression of ATP6 in vivo.•Expression of human COXII is modulated by chimeric TLI RNAs in HELA cells.

Endogenous mitochondrial genes encode critical oxidative phosphorylation components and their mutation results in a set of disorders known collectively as mitochondrial encephalomyopathies. There is intensive interest in modulating mitochondrial function as organelle dysfunction has been associated with numerous disease states. Proteins encoded by the mitochondrial genome cannot be genetically manipulated by current techniques. Here we report the development of a mitochondrial-targeted RNA expression system (mtTRES) utilizing distinct non-coding leader sequences (NCLs) and enabling in vivo expression of small mitochondrial-targeted RNAs. mtTRES expressing small chimeric antisense RNAs was used as translational inhibitors (TLIs) to target endogenous mitochondrial protein expression in vivo. By utilizing chimeric antisense RNA we successfully modulate expression of two mitochondrially-encoded proteins, ATP6 and COXII, and demonstrate the utility of this system in vivo and in human cells. This technique has important and obvious research and clinical implications.