Ribozyme-mediated repair of defective mRNA by targeted trans -splicing

RIBOZYMES can be targeted to cleave specific RNAs 1–8 , which has led to much interest in their potential as gene inhibitors 3,9,10 . Such fra/is-cleaving ribozymes join a growing list of agents that stop the flow of genetic information 11,12 . Here we describe a different application of ribozymes for which they may be uniquely suited. By targeted trans -splicing, a ribozyme can replace a defective por-tion of RNA with a functional sequence. The self-splicing intron from Tetrahymena thermophila 13 was previously shown to mediate trans -splicing of oligonucleotides in vitro 14,15 . As a model system for messenger RNA repair, this group I intron was re-engineered to regenerate the proper coding capacity of short, truncated lacZ transcripts. Trans -splicing was efficient in vitro and proceeded in Escherichia coli to generate translatable lacZ messages. Targeted frans -splicing represents a general means of altering the sequence of specified transcripts and may provide a new approach to the treatment of many genetic diseases.