title: Comparative toxicological study of the novel protein phosphatase inhibitor 19-Epi-okadaic acid in primary cultures of rat cerebellar cells.
abstract: Okadaic acid (OKA) and analogues are frequent contaminants of coastal waters and seafood. Structure analysis of the isolated OKA analogue 19-epi-OKA showed important conformation differences expected to result in lower protein phosphatase (PP) inhibitory potencies than OKA. However, 19-epi-OKA and OKA inhibitory activities versus PP2A were unexpectedly found to be virtually equipotent. To investigate the toxicological relevance of these findings, we tested the effects of 19-epi-OKA on cultured cerebellar cells and compared them with those of OKA and its isomer dinophysistoxin-2. 19-epi-OKA caused degeneration of neurites and neuronal death with much lower potency than its congeners. The concentration of 19-epi-OKA that reduced after 24h the maximum neuronal survival (EC5024) by 50% was ~300nM compared with ~2nM and ~8nM for OKA and dinophysistoxin-2, respectively. Exposure to 19-epi-OKA resulted also in less toxicity for cultured glial cells (EC5024,19-epi-OKA ~ 600nM; EC5024,OKA ~ 20nM). 19-epi-OKA induced apoptotic condensation and fragmentation of chromatin, activation of caspases, and activation of ERK1/2 MAP kinases, features previously reported for OKA and dinophysistoxin-2. Also, differential sensitivity to 19-epi-OKA was observed between neuronal and glial cells, a specific characteristic shared by OKA and dinophysistoxin-2 but not by other toxins. Our results are consistent with 19-epi-OKA being included among the group of toxins of OKA and derivatives and support the suitability of cellular bioassays for the detection of these compounds.
authors: Instituto Universitario de Biotecnología de Asturias, Departamento de Bioquímica y Biología Molecular, Universidad de Oviedo, Oviedo, Spain. neurolab@bioquimica.uniovi.es
authors: Maria-Teresa
authors: MT
authors: Fernández-Sánchez
authors: David
authors: D
authors: Cabrera-García
authors: Amaia
authors: A
authors: Ferrero-Gutierrez
authors: Anabel
authors: A
authors: Pérez-Gómez
authors: Patricia G
authors: PG
authors: Cruz
authors: Antonio H
authors: AH
authors: Daranas
authors: José J
authors: JJ
authors: Fernández
authors: Manuel
authors: M
authors: Norte
authors: Antonello
authors: A
authors: Novelli
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology / Q000187:drug effects*; D004789:Enzyme Activation; D015870:Gene Expression / Q000187:drug effects; D019319:Okadaic Acid / Q000031:analogs & derivatives* / Q000633:toxicity; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors*; D011494:Protein Kinases / Q000378:metabolism; D051381:Rats
chemical_list: C522300:19-epi-okadaic acid; D019319:Okadaic Acid; D011494:Protein Kinases; D010749:Phosphoprotein Phosphatases