Selection and Characterization of Active Hammerhead Ribozymes Targeted Against Cyclin E and E2F1 Full-Length mRNA

Proliferation of vascular smooth muscle cells is generally accepted as a key event in the development of restenosis following percutaneous transluminal angioplasty. To prevent human restenosis, we have designed a molecular strategy based on hammerhead ribozymes targeted against the mRNA of cyclin E and E2F1, two proteins relevant in cell cycle progression whose regulation is interconnected by a positive feedback loop. Following the identification of accessible ribozyme target sites by RNase H mapping, several hammerhead ribozymes were generated that cleave with comparable efficiency two different splice forms of cyclin E mRNA and the full-length and a truncated form of E2F1 RNA, respectively. The most active ribozymes were tested in vitro under single-turnover conditions yielding kreact/Km ratios between 36 and 73 × 104 M-1 min-1, which places them in the top range ribozymes targeted against long and structured substrates. In addition, we show that the most active ribozyme selected in vitro reduces specif...