The delivery and expression of hammerhead ribozymes to eukaryotic cells have largely been achieved using RNA polymerase II (pol II)-based promoters for transcription of ribozyme sequences. These constructs produce transcripts that are capped (5′-m7 G) at the 5′-end and contain long tracts of adenine residues (i.e., are polyadenylated) at the 3′-end. Although there is a large body of literature (1 that suggests the success of pol II-based ribozyme constructs in reducing target gene activity, several other studies have provided evidence for alternate modes of delivery. This chapter will review the methods for the use of RNA polymerase III-based delivery systems. In particular, it will focus on the use of tRNA molecules as delivery systems for hammerhead ribozymes.
