Okadaic Acid from Laboratory Cultures of a Dinoflagellate Alga: Effects on Protein Phosphorylation in C3H10T1/2 Fibroblasts

Abstract

Okadaic acid is a polyether carboxylic acid-containing compound of Mr 802, first isolated from species of the black sponge, Halichondria okadai and H. melanodocia (Tachibana et al., 1981). The compound is probably produced by the benthic marine dinoflagellate, Prorocentrum lima and may be absorbed by the sponge after feeding on this alga. Through progression of the food chain, okadaic acid has been shown to accumulate in the digestive glands of bivalves (Murakami et al., 1982) and is the major cause of diarrhetic shellfish poisoning (Hartshorne et al., 1989). Okadaic acid has also been shown to have potent tumour promoting activity (Suganuma et al., 1988), but unlike other promoters such as the phorbol ester TPA, okadaic acid does not activate protein kinase C (PRC) but is a specific inhibitor of protein phosphatases types 1 (PP1) and 2A (PP2A) (Cohen et al., 1989).