Microcystin-LR induced an inhibition of protein synthesis in isolated rat hepatocytes.
The effect of microcystin-LR, an inhibitor of protein phosphatases PP1 and PP2A, was studied on protein synthesis by measuring the incorporation of labelled amino acid into protein in isolated rat hepatocytes. Microcystin-LR inhibited protein synthesis in the first minutes of the incubation period, and half-maximum effect was obtained at about 60 nM. Such an inhibition was also observed in the presence of different protein phosphatase inhibitors, i.e. okadaic acid, calyculin A and microcystin-RR. This effect was observed in whole hepatocytes, in the supernatant of the post-mitochondrial fraction and in the microsomal fraction. It was independent of a substrate supply and of the labelled amino acid used. Furthermore, this inhibition preceded the previously reported glucose-6-phosphatase activation induced by microcystin-LR [Claeyssens, Chédeville and Lavoinne (1993) FEBS Lett. 315, 7-10].
Claeyssens
S
S
Groupe de Biochimie et Physiopathologie Digestive et Nutritionnelle, U.F.R. Médecine-Pharmacie, Saint-Etienne du Rouvray, France.
Francois
A
A
Chedeville
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A
Lavoinne
A
A
D000818:Animals; D002478:Cells, Cultured; D008099:Liver / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D008387:Marine Toxins; D052998:Microcystins; D010456:Peptides, Cyclic / Q000494:pharmacology*; D014176:Protein Biosynthesis; D051381:Rats; D017208:Rats, Wistar; D013347:Subcellular Fractions
D008387:Marine Toxins; D052998:Microcystins; D010456:Peptides, Cyclic; C057862:cyanoginosin LR