Distinct roles of PKC isoforms in NCAM-mediated neurite outgrowth.
The role of protein kinase C (PKC) isoforms in the neural cell adhesion molecule (NCAM)-mediated neurite outgrowth was tested using a co-culture system consisting of fibroblasts with or without NCAM expression upon which either primary cerebellar granular neurones (CGN) or pheochromocytoma (PC12-E2) cells were grown. The latter transiently expressed various PKC isoforms and domains derived from selected PKCs. PKC inhibitors of various specificity inhibited NCAM-stimulated neuritogenesis from CGN, indicating that PKC is involved in this process. Moreover, stimulation by the NCAM-mimetic peptide, C3d, elicited phosphorylation of PKC in CGN. Expression of kinase-deficient forms of PKCalpha, betaI and betaII blocked NCAM-mediated neurite extension, but had no effect on nerve growth factor (NGF)-mediated neurite outgrowth. Expression of two PKCepsilon constructs: (i) a fragment from PKCepsilon encompassing the pseudosubstrate, the C1a domain (including the actin-binding site, ABS), and parts of the V3 region, or (ii) the PKCepsilon-specific ABS blocked NCAM-mediated neurite extension in both cases. These two constructs also partially inhibited NGF-stimulated neuritogenesis indicating that PKCepsilon is a positive regulator of both NCAM- and NGF-mediated differentiation. We suggest that PKCepsilon is a common downstream mediator for several neuritogenic factors, whereas one or more conventional PKCs are specifically involved in NCAM-stimulated neurite outgrowth.
Kolkova
Kateryna
K
Protein Laboratory, Institute of Molecular Pathology, University of Copenhagen, Copenhagen, Denmark. katya@plab.ku.dk
Stensman
Helena
H
Berezin
Vladimir
V
Bock
Elisabeth
E
Larsson
Christer
C
D000818:Animals; D049108:Cell Enlargement / Q000187:drug effects; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D007211:Indoles / Q000494:pharmacology; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000502:physiology; D008301:Maleimides / Q000494:pharmacology; D019006:Neural Cell Adhesion Molecules / Q000502:physiology*; D016501:Neurites / Q000187:drug effects / Q000502:physiology*; D016716:PC12 Cells; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000502:physiology*; D051381:Rats
D007211:Indoles; D007527:Isoenzymes; D008301:Maleimides; D019006:Neural Cell Adhesion Molecules; C099154:ruboxistaurin; D011493:Protein Kinase C