The roles in neuronal differentiation of Ca^<2+>/calmodulin-dependent phosphorylation of microtubule proteins

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1) In order to investigate the physiological roles of Ca^<2+>/calmodulin-dependent protein kinase II (CaM kinase II) in neuronal differentiation, we transfected the cDNA of the alpha subunit of mouse CaM kinase II into PC12 cells. We have established the subclonal cell lines that constitutively express the transfected CaM kinase II.The phosphorylation of microtubule-associated protein 2 (MAP2) in these cell lines was higher than in the wild type cells, and was enhanced by treatment with ionomycin. 2) The two antiphosphopeptide antibodies to tau indicate that tau in the peripheral nervous system and Alzheimer's disease brain is highly phosphorylated at serine 199, serine 202 and serine 396.3) We synthesized a peptide (MAP2 peptide) which included serine 1562 of MAP2. MAP2 peptide was strongly phosphorylated by CaM kinase II.4) We prepared antiphosphopeptide antibody which reacted with MAP2 phosphorylated at serine 1562 by CaM kinase II.5) The phosphorylation of MAP2 in cerebellar culture cells was enhanced by treatment with ionomycin.These results suggest that CaM kinase II regulates the functions of MAP2 in the cells and that phosphorylation of tau is increased in Alzheimer's disease brain. The antiphosphopeptide antibody to MAP2 is useful for the investigation of phosphorylation of MAP2 by CaM kinase II in the cells.