Spatioselective Imaging of Noncoding RNAs in Mitochondria via an Organelle-Specific DNA Assembly Strategy.

Precise imaging of noncoding RNAs (ncRNAs) in specific organelles allows decoding of their functions at subcellular level but lacks advanced tools. Here we present a DNA-based nanobiotechnology for spatially selective imaging of ncRNA (e.g., microRNA (miRNA)) in mitochondria via an organelle-specific DNA assembly strategy. The target miRNA-initiated assembly of DNA hairpins is inhibited by the block of toehold-mediated strand displacement reaction but can be exclusively activated by a mitochondria-encoded ribosomal RNA (rRNA) for hybridization chain reaction, enabling spatial control over miRNA imaging. We demonstrate that the conditionally controlled DNA assembly technology allows for minimization of nonspecific activation and thus improves the spatial precision of miRNA detection. In addition, the strategy is adaptable to visualizing other ncRNAs such as long noncoding RNAs in mitochondria, highlighting the universality of the approach. Overall, this work provides a useful tool for spatially selective imaging of ncRNAs and investigating the functions of organelle-located RNA.