Ribozyme expression

Trans-splicing ribozymes Expression of enzyme capable Expression of cytotoxic or... 

RNA pol III promoters, including tRNA, adenovirus VAl, Ul, and U6 small nuclear RNA derivatives, have allowed ubiquitous and very high intracellular levels of ribozyme expression. Several creative permutations, such as the combination of two promoters driving the same ribozyme gene or the placement of the ribozyme expression cassette within the U3 region of a Long terminal repeat, to produce a double-copy retroviral vector led to further increases in ribozyme expression. Finally, multiple ribozymes can be expressed within the same RNA transcript or from multiple promoter-ribozyme cassettes. 

Therapeutics and target validation studies will certainly be tested in animals. Ribozymes have been used in transgenic mice to create disease models such as diabetes by selectively downregulating the hexokinase mRNA in pancreatic islets. In this case, the ribozyme expression was under the control of the insulin promoter, and was therefore only expressed in the pancreatic beta cells. Retroviral delivery of ribozymes targeted against neuregulin-1 in a chick blastoderm resulted in the same embryonic lethal... 

Figure 2. Effects of ribozyme-expression plasmids specific for cleavage of CBP mRNA on the levels of CBP in a transient-expression assay. Relative levels of CBP were compared by an amplified sandwich ELISA. Normalized levels of CBP in wild-type (WT) F9 cells were taken arbitrarily as 100%. All values are the averages of results from at least three experiments and the standard deviation for each value relative to the value for WT cells is indicated.

Figure 6. Levels of the cdk inhibitor p27 P during the retinoic acid-induced (RA-induced) differentiation of wild-type (WT) and ribozyme-expressing F9 cells. Normalized levels of p27Kipi p9 (-gi]s taken arbitrarily as 1.0. All values are the averages of results...

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