Modular structure of 4.5SH RNA. The sensor module (target binding via base-pairing) recognizes and binds to abnormal sequences. The effector binding module brings in molecules that modulate alternative splicing to prevent incorporation of abnormal sequences in mRNA. (Illustration: Shinichi Nakagawa)

In mice, 4.5SH RNA acts as a natural gene therapy agent, preventing the inclusion of mutations in RNA (left). By engineering recombinant 4.5SH RNA, it may be possible to apply this system to treat genetic diseases in humans (right). (Illustration: Shinichi Nakagawa)