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Keywords:

  • PKC isoforms;
  • epsilon;
  • neurons;
  • culture;
  • neuroblasts;
  • glia;
  • development;
  • immunocytochemistry;
  • cell lineage

Abstract

Protein kinase C (PKC) is expressed as many isoforms and in high quantities in the central nervous system (CNS), which suggests an important role for this enzyme in neuronal development and function. We used specific antibodies to investigate the expression of the known PKC isoforms in extracts from chick major CNS areas during embryogenesis, from day 3 (E3) of incubation to day 1 post-hatching (P1). PKC-ε was the predominant isoform and was expressed from E6 onward in all brain regions, except retina (E12 and on). PKC-α/β and -ζ isoforms were expressed at lower levels prior to PKC-ε expression and throughout embryogenesis. No other isoforms were detected in neural tissue preparations. We then used neural culture systems derived from the chick CNS to study the expression of PKC isoforms in neuroblasts, cortical neurons, and cortical glial cells. Western blotting and immunostaining of neuroblastenriched cultures, derived from E3 CNS, showed only the Ca2+-dependent PKC-α/β to be present. Studies on neuronal cultures derived from E6 cerebral hemispheres revealed only the Ca2+-independent PKC-ε to be expressed in neurons, as predicted by the developmental studies on tissue homogenates. PKC-ε immunoreactivity was seen intracellularly in differentiating neurons, regardless of their neurotransmitter phenotypes, and it correlated well with the level of neuronal activity. Furthermore, PKC-α/β immunoreactivity was verified on glia cells, as the glial lineage emerges in E15 cortical cultures. These data suggest that PKC-ε expression is associated with the final neuroblast division in neurons, and the correlation of PKC isoform expression and neural cell lineage is discussed. © 1993 Wiley-Liss, Inc.