Restoration of mRNA splicing by a second-site intragenic suppressor in the T4 ribonucleotide reductase (small subunit) self-splicing intron

Ribozyme: A clinical tool

Catalytic RNAs (ribozymes) are capable of specifically cleaving RNA molecules, a property that enables them to act as potential antiviral and anti-cancer agents, as well as powerful tools for functional genomic studies. Recently, ribozymes have been used successfully to inhibit gene expression in a variety of biological systems in vitro and in vivo. Phase I clinical trials using ribozyme gene therapy to treat AIDS patients have been conducted. Despite initial success, there are many areas that require further investigation. These include stability of ribozymes in cells and designing highly active ribozymes in vivo, identification of target sequence sites and co-localization of ribozymes and substrates, and their delivery to specific tissues and maintenance of its stable long-term expression. This review gives a brief introduction to ribozyme structure, catalysis and its potential applications in biological systems as therapeutic agents.

Ribozymes: a modern tool in medicine

Since the discovery of ribozymes and self-splicing introns, it has been estimated that this biological property of RNA combined with other recombinant DNA technologies would become a tool to combat viral diseases and control oncogenes. These goals seem like a distinct possibility now. However, there is still a lot to be learned about the mobility of RNA inside the cells and the cellular factors that can impede ribozyme action in order to capitalize fully on the targeted RNA inactivation property of ribozymes. The most effective approach to maximize ribozyme function in a complex intracellular environment is to understand as much as possible about the intracellular fate of the RNA that is being targeted. As new techniques in cell biology become available, such understanding will be less problematic. Fundamental studies of ribozyme structure and mechanism of catalysis are flourishing both at the academic and industrial level and it can be expected that many new developments will continue to take place in these areas in the near future. Here, we review the design, stability and therapeutic application of these technologies illustrating relevant gene targets and applications in molecular medicine. Relevant problems in implementation of the technology, group I and II introns and the differences in applications, ribozyme structure and the application of this technology to virus attack and oncogene downregulation are discussed. Also some of the latest RNA-based technologies such as siRNA, RNA/DNA duplexes and RNA decoys have been introduced.