RIBOZYME-MEDIATED RNA DEGRADATION IN NUCLEI SUSPENSION

Ribozymes containing 2'-fluoro- and 2'-amino-modified pyrimidine nucle osides in combination with terminal phosphorothioate linkages were tar geted against HTLV-I fax RNA. In oder to examine the activity of such chemically modified ribozymes in the nuclear environment, they were in cubated with nuclei of a Tax-transformed mouse fibroblast cell line. R ibozyme cleavage of tax RNA was analyzed by the RNase protection assay . Comparison of the cleavage of tax RNA isolated nuclei with that of t ax RNA present in nuclei suspension revealed a 30 times more efficient cleavage of the latter one. Pre-treatment with proteinase K and SDS a bolished the enhancement of the ribozyme-mediated RNA cleavage. Cataly tically inactive ribozymes did not yield any cleavage products. These results demonstrate an augmenting effect of nuclear proteins on the ri bozyme-mediated RNA cleavage.