Initiation of transcription in permeabilized Novikoff hepatoma cells

Novikoff hepatoma cells, grown in monolayer cultures, when permeabilized by treatment with lysolecithin, incorporated 3H-UTP at a high rate for 2 hours at 25 degrees. The incorporation was inhibited by initiation inhibitors such as rifampicin AF/013, heparin and aurintricarboxylic acid. About 75% of RNA polymerase II, and 45% of RNA polymerase I activities were inhibited by rifampicin AF/013. In contrast, transcription in isolated nuclei was not inhibited either by rifampicin AF/013 or heparin. The permeabilized cells apparently retain the mechanisms for reinitiation in vitro and may be a useful model for studies on the effects of proteins on gene transcription.