iTRAQ‐based proteomic study of the effects of microcystin‐LR on medaka fish liver

Microcystins are cyanotoxins that occur in ground water and thus pose a potential health risk. Microcystin‐LR (microcystin‐leucine‐arginine) is a potent hepatotoxin, and is suspected of being a tumour promoter. Poisoning with this toxin causes several dysfunctions in hepatocytes by inhibiting protein phosphatases 1 and 2A, and notably produces oxidative stress, disrupts the cytoskeleton, and deregulates mitogen‐activated protein kinase pathway. Medaka fish ( Oryzias latipes ) was chosen as a model for studying the effects of this cyanotoxin on liver proteins using a gel‐free approach, iTRAQ. Fish were gavaged with microcystin‐LR. Two hours later, 325 proteins could be identified by Scaffold Q+ and 32 proteins revealed statistically significant variations above a ∣0.2∣ threshold of log 2 ratio by comparison with control. These proteins are mostly involved in the translation and maturation of proteins, lipid metabolism and detoxification. Notably, apolipoproteins are deregulated which indicates a possible alteration of chylomicron‐mediated transport.