Nuclease-resistant ribozyme

Flory, C.M., Pavco, P.A., Jarvis, T.C., Lesch, M.E., Wincott, F.E., Beigelman, L. et al. (1996) Nuclease-resistant ribozymes decrease stromelysin mRNA levels in rabbit synovium following exogenous delivery to the knee joint. Proc. Natl. Acad. Sci. USA, 93, 754-758. Forster, A.C. and Altman, S. (1990) External guide sequences for an RNA enzyme. Science, 249, 783-786. 

Profile Founded in 1992, the company commercializes patented ribozyme technology in the human therapeutic, agricultural, animal health, and diagnostic fields, through both internal efforts and collaborations with strategic partners. It announced a collaboration with Protogene Laboratories, Inc. in December 1996 one goal is to create an instrument that will synthesize thousands of RPI s proprietary nuclease resistant ribozymes, combinatorial libraries of other compounds, and methods that allow for low-level quantitative detection of RNA in cells. 

Substantial progress has also been reported with regard to the synthesis and testing of nuclease-resistant ribozyme drugs. Modifications including phosphorothioates and nucleoside analogs have been demonstrated to be incorporable in many sites in hammerhead ribozymes, to increase nuclease resistance and support retained ribozyme activity (59-61). In fact, modified relatively nuclease-resistant ribozymes were reported to decrease the target, stromelysin, mRNA levels in knee joints of rabbits after intra-articular injection (62). Further, the pharmacokinetics of a relatively nuclease-stable hammerhead ribozyme were determined after intravenous (i.v.), subcutaneous (s.c.), or intraperitoneal (i.p.) administration to mice. The ribozyme... 

Usman N, Blatt LRM (2000) Nuclease-resistant synthetic ribozymes developing a new class of therapeutics. J Clin Invest 106 1197-1202... 

One of the shortcomings of ribozymes is that they are short single-stranded RNA moieties with a simple secondary structure. It is possible that their use in gene therapy could be limited because they could be highly susceptible to cellular nucleases. Present research is aimed at producing ribozymes that are more resistant to degradation. 

In order to obtain therapeutic agents based on synthetic ribozymes, it is necessary to modify these structures chemically. Such modifications - as in the traditional antisense strategy - should confer resistance to nucleases, selectivity, and proper hybridization and uptake characteristics. In the case of ribozymes, the design of new modified nucleotides becomes more complex, since correct folding of the nucleic acid is needed in order to maintain the catalytic activity. Several studies (e.g.. X-ray structure elucidation and mapping with modified nucleotides) have shown that the presence of the 2 -hydroxyl group at specific positions in the catalytic core is essential for hydrolytic activity. Ribozymes are currently used in larger screens as a... 

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