Jean-Paul Bourdineaud, Sébastien Cambier1, Sandra Prévéral, Patrice Catty and Cyrille Forestier
ABC transporters belonging to the subfamilies ABCB (MDR/TAP) and ABCC (CFTR/MRP) are likely to play a role in the detoxification of metallic pollutants. We made an inventory of the transcriptional response of 10 abcb and 9 abcc gene members in zebrafish Danio rerio exposed for 7 days to ionic cadmium (89 nM), zinc (7.3 μM), or a blend of both metals. These concentrations correspond to those found in a polluted tributary of the Lot River, France. The general trend was that cadmium is rather an up-regulator (but for high accumulation factors only) whereas zinc is rather a repressor. In muscles the expression pattern of ABC genes in response to metals appeared unpredictable since there was no relationship between differential expression and metal accumulation. Although no increase of zinc burden was observed in fish muscles and gills exposed to zinc, that metal repressed 9 and 4 ABC genes in muscles and gills, respectively. Despite a 3-fold increase in zinc burden in brain, it triggered the down-regulation of 3 ABC genes. Also, despite an accumulation factor of 7 in muscles, cadmium repressed 2 ABC genes in muscles. However, in gills and liver cadmium exposure caused the up-regulation of 4 and 6 ABC genes linked to accumulation factors of 33 and 25, respectively. Beside MDR- and MRP-transporter encoding genes, metals up regulated other genes encoding zebrafish homologues of TAP2 (abcb3 and abcb3L1), ATM1 (abcb7), M-ABC1 (abcb8), TAPL (abcb9), SUR1 (abcc8) and SUR2 (abcc9) transporters.
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