Differential expression of protein kinase C isozymes in rat glial cell cultures

Protein kinase C (PKC) is a family of closely related enzymes implicated in molecular processes involved in growth and differentiation in a variety of cells. We studied the presence and distribution of 4 PKC isozymes in glial cell cultures of the rat hippocampus employing antisera raised against synthetic peptides predicted from the cDNA sequences corresponding to the C-terminal portion of 4 PKC isoforms, α, βI, βII, and γ. PKC(α) and -(βII), but neither PKC(βI) nor -(γ) isoforms were detected in glial cultures of the rat hippocampus. Anti-PKC(α) immunostained all glial cells, whereas anti-PKC(βII) faintly stained about 20% of total glial cells resembling the type-2 astrocyte that were GFAP immunopositive, with few processes. Anti-PKC(βII) did not stain about 80% of the glial fibrillary acidic protein (GFAP)-immunopositive cells with a few thick processes which resembled the type-1 astrocyte. A few cells that stained intensely with anti-PKC(βII) were GFAP immunopositive and possessed fine, but well-developed, multiple processes. Faint PKC(βII) immunoreactivity was also detected among anti-MBP-positive cells (possibly oligodendrocytes), RCA-1-positive cells (possibly microglia), and small, oval, anti-GFAP-positive cells. These results suggest the involvement of distinct PKC isoforms in different glial functions.