CDNA CLONING AND SEQUENCING OF CA2+ CALMODULIN-DEPENDENT PROTEIN-KINASE II-ALPHA SUBUNIT AND ITS MESSENGER-RNA EXPRESSION IN DIISOPROPYL PHOSPHOROFLUORIDATE (DFP)-TREATED HEN CENTRAL-NERVOUS-SYSTEM/

Diisopropyl phosphorofluoridate (DFP) produces delayed neurotoxicity, known as organophosphorus ester-induced delayed neurotoxicity (OPIDN), in hen, human, and other sensitive species. A single dose of DFP (1.7 mg/kg, se.) produces first mild ataxia followed by paralysis in 7-14 days in hens. DFP treatment also increases in vitro autophosphorylatio n of Ca2+ calmodulin-dependent protein kinase II (CaM kinase II) and t he phosphorylation of several cytoskeletal proteins in the hen brain. To investigate whether increase in CaM kinase II activity is associate d with increased expression of its mRNA, we cloned and sequenced CaM k inase II alpha subunit cDNA, and used it to study CaM kinase II expres sion in brain regions and spinal cord. Hen CaM kinase II a subunit dif fers in 7 amino acids from that of rat CaM kinase II Its mRNA occurs p redominantly as a 6.7 kb message, which is very close to that of human CaM kinase II alpha subunit. Northern blot analysis showed a transien t increase in CaM kinase II alpha subunit mRNA in the cerebellum and s pinal cord of DFP-treated chickens. The increase in CaM kinase II mRNA expression is consistent with the previously reported increase in its activity in brain and spinal cord, and its increased expression only in cerebellum and spinal cord, which are sensitive to the Wallerian-ty pe degeneration characteristic of OPIDN, suggests the probable role of this enzyme in delayed neurotoxicity.