PKCα-specific ribozymes substantially inhibit proplatelet formation.

(A) The proplatelet assay was performed in the presence of ribozymes R1, R2, or the control ribozyme, which is identical to R1 except that the binding site is present in reverse orientation. The numbers of proplatelet-bearing MKs, expressed as a percentage of the control, were significantly decreased in the presence of R1 and R2. No effect on total cell number was found. The experiments were performed 3 times with similar results. ░, control ribozyme; ▧, R1 ribozyme; ▨, R2 ribozyme. (B) Equal numbers of MKs were transfected with ribozymes. PKCα protein expression was then assessed by Western blot analysis 48 hours after transfection and quantified by phosphoimager. The amount of PKCα expression in R1- and R2-transfected MKs was 25% and 51% of the control, respectively (upper panel). The blot was stripped and reprobed with the ERK2 MAPK antibody to ensure an equal number of cells per lane (lower panel).