engleski

Expression and characterization of rainbow trout (Oncorhynchus Mykiss) BCRP (ABCG2) in SF9 insect cells

The cellular efflux transporter BCRP (abcg2) belongs to the ATP-binding cassette (ABC) superfamily and plays an importantrole in elimination of xenobiotics in mammals. To date, its role in fish remains elusive . To invstigate and characterize its role we expressed rainbow trout (Oncorhynchus mykiss) BCRP in both Sf9 insect cells and human HEK293 cell line. For direct comparison of fish and mammalian transporters the human BCRP was also expressed in the same protein expression systems. We found that fish BCRP is not glycosylated in the same way as its human counterpart. Furthermore, trout BCRP exhibited much weaker modulation of transport activity in the presence of cholesterol, a major component of cell membranes that strongly affects the transport rate (Vm or Km values) of human BCRP. Km values for ATP were similar in the absence of cholesterol for both human (0.38 mM) and trout BCRP (0.11 mM). Cholesterol increased both Km 2.5-fold. Although cholesterol did not change the baseline transporter activity, it changed the transport rate (Vm values) of fish and human BCRP in the presence of the model substrate sulfasalazine. After initial biochemical characterization of the two transporters, we tested 40 model compounds using the ATPase assay in order to determine and compare human and trout BCRP substrates/inhibitors specificity. Overall, we found significant correlation (r2=0.64) in substrates/inhibitors affinity between trout and human BCRP. Among the most interesting findings was the high affinity transport rate of trout transporter for the PAHs benzo[a]pyren and 2-acetylamninofluorene. Our data show that BCRP is an efflux transporter for PAHs in fish.

ABC transporters in fish ; BCRP ; cholesterol

nije evidentirano