Subcellular Distribution of Protein Kinase C in Rat Colonie Epithelial Cells with Different Proliferative Activities1

Activation of Ca2*and phospholipid-dependent protein kinase C (PKC) is associated with increased proliferation in several cell types. When activated, PKC is tightly bound to the particulate cell fraction. Accord ingly, we examined the subcellular distribution of PKC in superficial (nonproliferative) and proliferativi.-colonie epithelial cells from rat colonie mucosa. PKC was determined in soluble and particulate fractions of these cells following partÃ-a!purification of enzyme activity of cellular homogenates by DEAE-cellulose chromatography. In the superficial cells, 90% of the PKC was associated with the soluble fraction. By contrast only 42% of the enzyme activity was found in the soluble fraction of prolifer ativi' cells. The specific activity of protein kinase C was higher in the particulate fraction of proliferative compared to superficial cells when expressed as a function of either particulate protein or cellular DNA content. Addition of deoxycholate or 12-O-tetradecanoylphorboI-13-acetate induced a translocation of protein kinase C from the soluble to the particulate fraction. |'I l|Tliymidine incorporation into DNA was higher in colonie epithelial cells isolated from the colons of rats which had been exposed to deoxycholate or 12-0-tetradecanoylphorbol-13-acetate in vivo. Treatment of rats with l-(5-isoquinolinyl)-2-methylpiperazine(H-7) suppressed basal [3H|thymidine incorporation into DNA and increases in this parameter induced by 12-0-tetradecanoylphorbol-13-acetate and deoxycholate. The results are consistent with a positive role for activation of protein kinase C in the control of colonie epithelial proliferation.