A conformational switch-controlled RNA sensor based on orthogonal dCas12a for RNA imaging in live cells

RNA imaging technology is essential for understanding the complex RNA regulatory mechanisms and serves as a powerful tool for disease diagnosis. However, conventional RNA imaging methods often require multiple fluorescent tags for the specific labeling of individual targets, complicating both the imaging process and subsequent analysis. Herein, we develop an RNA sensor that integrates a blocked CRISPR RNA (crRNA)-based conformational switch with a controllable CRISPR activation (CRISPRa) system and apply for RNA imaging. By leveraging nuclease-inactive Cas12a (dCas12a)-mediated processing of precursor crRNA (pre-crRNA) and the orthogonality of dCas12a from different bacteria, our sensor establishes an artificial link between two unrelated RNA targets, enabling cells to sense one RNA target and image another with a single fluorescent signal. By visualizing a single target for dual-target analysis, our method significantly reduces the reliance on multiple fluorescent tags. Our sensor provides a new platform for RNA imaging, enhancing both biomedical research and the development of advanced molecular diagnostics.