J. Avila et al., PHOSPHORYLATION OF MICROTUBULE-ASSOCIATED PROTEINS BY PROTEIN-KINASE CK2 IN NEURITOGENESIS, Cellular & molecular biology research, 40(5-6), 1994, pp. 573-579
Phosphorylation of microtubule-associated protein MAP1B and the neuron
al-specific beta III-tubulin isoform takes place during neurite growth
in neuroblastoma cells. Protein kinase CK2 (formerly referred to as c
asein kinase 2) is possibly involved in beta III-tubulin phosphorylati
on. As for MAP1B, there are at least two types of phosphorylation; one
catalyzed by proline-directed protein kinases and another catalyzed b
y CK2, Protein kinase CK2 is primarily localized to the nuclei in prol
iferating neuroblastoma cells, whereas an increased amount of the enzy
me is present in the cytoplasm of postmitotic cells bearing neurites.
Treatment of neuroblastoma cells with an antisense oligonucleotide whi
ch specifically results in CK2 catalytic subunit depletion inhibits ne
uritogenesis. CK2 depletion is accompanied by dephosphorylation of MAP
1B on the corresponding phosphorylatable sites. This dephosphorylation
is paralleled by a release of MAP1B from microtubules. These results
suggest that MAP1B phosphorylation by CK2 may be required for the asse
mbly of microtubules within neurites. Other neuronal cytoskeletal prot
eins including MAP1A and tau are also substrates for CK2, indicating a
role for the enzyme in the regulation of cytoskeletal functions also
in mature neurons.