Expression of protein kinase C isozymes in primary neuronal cultures of the rat cerebellum.

Protein kinase C (PKC), a family of closely related enzymes, has been implicated in molecular processes involved in differentiation in a variety of cells, including neuronal cells. We studied the presence and distribution of four PKC isozymes immunocytochemically in primary neuronal cultures of the rat cerebellum. We employed four anti-PKC antisera raised against synthetic peptides predicted from the cDNA sequence of the C-terminal portion of four PKC isozymes, alpha, beta I, beta II, and gamma. The majority of neurons were PKC(beta II) immunoreactive both in the early and late (14 days) stage of culture, whereas PKC(alpha)-, (beta I)-, and (gamma)-immunoreactive neurons were most abundant in the late stage of culture. Immunoreactivity of each PKC was high in the cytoplasm, processes, and growth cones. Prominent nuclear staining was observed with anti-PKC(gamma) antibody. These results are in contrast with in vivo results where each PKC isozyme is localized in a distinct population of neurons and subcellular compartment, suggesting the presence of regulatory mechanisms for PKC expression and compartmentalization in vivo.