FIGURE 4.

Uncoupling transcription and 3′ end formation reduces mRNA accumulation from the 5′ intron construct, but has little effect on 3′ intron mRNA. (A) Efficiency of ribozyme (rz) self-cleavage. A probe spanning the ribozyme sequence (probe R) was hybridized to 1.5 μg (lanes 1,3,5) or 6 μg (lanes 2,4,6) total RNA from transfected cells. No intron plasmid DNA was used to obtain protected fragments corresponding to uncleaved mRNA (lane 7). (B) Comparison of mRNA levels from cells transfected with either the parental constructs (Fig. 1A ▶) or their ribozyme-containing equivalents. RPAs were performed with probe B on 1.5 or 6 μg total RNA. Lower panel shows endogenous cyclophilin mRNA levels. (C) Summary of TPI/Renilla mRNA levels for each construct relative to the no-intron/no-ribozyme control. Numbers represent the average of two independent experiments and error bars indicate standard deviations.