title: Protein kinase C delta regulates neural cell adhesion molecule polysialylation state in the rat brain.
abstract: Polysialylation of neural cell adhesion molecule (NCAM PSA) modulates cell-cell homophilic binding and signalling during brain development and the remodelling of discrete brain regions in the adult. Following learning, a transient increase in the frequency of polysialylated neurones occurs in the dentate gyrus of the hippocampal formation, and this has been correlated with the selective retention and/or elimination of synapses that are transiently overproduced during memory consolidation. We now demonstrate that protein kinase C delta (PKCdelta) negatively regulates polysialyltransferase activity in the rat brain during development and also in the hippocampus during memory consolidation, where its down-regulation in the Golgi membrane fraction coincides with the transient increase in NCAM PSA expression. Decreased expression of PKCdelta was also observed in the hippocampus of rats reared in a complex environment and this directly contrasted the significant increase in frequency of hippocampal polysialylated neurones observed in these animals. These effects were isoform-specific as no change in total PKC enzyme activity was detected during memory consolidation and complex environment rearing had no effect on the hippocampal expression of PKCalpha, beta, gamma or epsilon. By sequential immunoprecipitation and immunoblot analysis, phosphorylation of polysialyltransferase protein(s) was (were) demonstrated to occur on both serine and tyrosine residues and this was associated with decreased enzyme activity. Moreover, a similar experimental approach revealed the degree of PKCdelta co-precipitation with polysialyltransferase protein(s) to be inversely correlated with polysialyltransferase activity. These findings support in vitro evidence indicating PKCdelta to regulate polysialyltransferase activity and NCAM polysialylation state.
authors: Department of Pharmacology, The Conway Institute, University College, Dublin, Ireland.
authors: H C
authors: HC
authors: Gallagher
authors: K J
authors: KJ
authors: Murphy
authors: A G
authors: AG
authors: Foley
authors: C M
authors: CM
authors: Regan
mesh_terms: D000818:Animals; D001362:Avoidance Learning / Q000502:physiology; D001921:Brain / Q000201:enzymology*; D001923:Brain Chemistry; D002448:Cell Adhesion; D002455:Cell Division; D018891:Dentate Gyrus / Q000378:metabolism; D004777:Environment; D004789:Enzyme Activation; D006031:Glycosylation / Q000187:drug effects; D006056:Golgi Apparatus / Q000201:enzymology; D006624:Hippocampus / Q000378:metabolism; D007425:Intracellular Membranes / Q000201:enzymology; D007527:Isoenzymes / Q000502:physiology*; D008297:Male; D008568:Memory / Q000502:physiology; D011939:Mental Recall / Q000502:physiology; D051379:Mice; D009419:Nerve Tissue Proteins / Q000502:physiology*; D039842:Neural Cell Adhesion Molecule L1; D019006:Neural Cell Adhesion Molecules / Q000096:biosynthesis* / Q000378:metabolism*; D009447:Neuroblastoma / Q000473:pathology; D010766:Phosphorylation; D010768:Phosphoserine / Q000032:analysis; D019000:Phosphotyrosine / Q000032:analysis; D011493:Protein Kinase C / Q000502:physiology*; D051745:Protein Kinase C-delta; D011499:Protein Processing, Post-Translational / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D011930:Reaction Time / Q000502:physiology; D012794:Sialic Acids / Q000096:biosynthesis* / Q000378:metabolism*; D012799:Sialyltransferases / Q000737:chemistry / Q000378:metabolism; D013347:Subcellular Fractions / Q000201:enzymology; D014407:Tumor Cells, Cultured
chemical_list: D007527:Isoenzymes; D009419:Nerve Tissue Proteins; D039842:Neural Cell Adhesion Molecule L1; D019006:Neural Cell Adhesion Molecules; D012794:Sialic Acids; C021319:polysialic acid; C103469:polysialyl neural cell adhesion molecule; D010768:Phosphoserine; D019000:Phosphotyrosine; C046778:CMP-N-acetylneuraminate-poly-alpha-2,8-sialosyl sialyltransferase; D012799:Sialyltransferases; C497259:Prkcd protein, mouse; C497260:Prkcd protein, rat; D011493:Protein Kinase C; D051745:Protein Kinase C-delta