Specific Targeting and Imaging of RNA G‐Quadruplex (rG4) Structure Using Non‐G4‐Containing l‐RNA Aptamer and Fluorogenic l‐Aptamer

Abstract

AbstractRNA G‐quadruplex structures (rG4s) play important roles in the regulation of biological processes. So far, all the l‐RNA aptamers developed to target rG4 of interest contain G4 motif itself, raising the question of whether non‐G4‐containing l‐RNA aptamer can be developed to target rG4. Furthermore, it is unclear whether an l‐Aptamer‐based tool can be generated for G4 detection in vitro and imaging in cells. Herein, a new strategy is designed using a low GC content template library to develop a novel non‐G4‐containing l‐RNA aptamer with strong binding affinity and improved binding specificity to rG4 of interest. The first non‐G4‐containing l‐Aptamer, l‐Apt.1‐1, is identified with nanomolar binding affinity to amyloid precursor protein (APP) D‐rG4. l‐Apt.1‐1 is applied to control APP gene expression in cells via targeting APP D‐rG4 structure. Moreover, the first l‐RNA‐based fluorogenic bi‐functional aptamer (FLAP) system is developed, and l‐Apt.1‐1_Pepper is engineered for in vitro detection and cellular imaging of APP D‐rG4. This work provides an original approach for developing non‐G4‐containing l‐RNA aptamer for rG4 targeting, and the novel l‐Apt.1‐1 developed for APP gene regulation, as well as the l‐Apt.1‐1_Pepper generated for imaging of APP rG4 structure can be further used in other applications in vitro and in cells.