Differential expression of protein kinase C isoform genes in three murine erythroleukemia cell variants: implication for chemical induced differentiation.

The presence of alpha, delta, epsilon, theta, and zeta protein kinase C isoforms in DS19 murine erythroleukemia cells has been established in this study. In addition, the mRNA levels of these isozymes have been measured by quantitative reverse transcriptase-polymerase chain reaction. Isoform delta has been found to be the most abundant isotype, whereas isoform zeta resulted to be present in only few copies. Furthermore, the expression levels of all five protein kinase C isozymes have been studied in three cell clones, derived from parental DS19 cells and characterized by different susceptibilities to differentiation. This comparative analysis indicated that the calcium-independent isozymes (delta, epsilon, zeta, and theta) display significantly higher expression levels in cells less prone to differentiation. On the other hand, the mRNA levels of the only calcium-dependent isoform present (alpha) fluctuate poorly from one cell clone to the other, but are the highest in the cell clone characterized by the fastest rate of differentiation. This study represents the first complete characterization of the basal levels of specific protein kinase C isotypes in different murine erythroleukemia cell clones and provides further evidence for the role of individual isozymes in the early events that trigger chemical induced murine erithroleukemia cell differentiation.