title: Multidrug efflux transporters limit accumulation of inorganic, but not organic, mercury in sea urchin embryos.
abstract: Mercuric compounds are persistent global pollutants that accumulate in marine organisms and in humans who consume them. While the chemical cycles and speciation of mercury in the oceans are relatively well described, the cellular mechanisms that govern which forms of mercury accumulate in cells and why they persist are less understood. In this study we examined the role of multidrug efflux transport in the differential accumulation of inorganic (HgCl(2)) and organic (CH(3)HgCl) mercury in sea urchin (Strongylocentrotus purpuratus) embryos. We found that inhibition of MRP/ABCC-type transporters increases intracellular accumulation of inorganic mercury but had no effect on accumulation of organic mercury. Similarly, pharmacological inhibition of metal conjugating enzymes by ligands GST/GSH significantly increases this antimitotic potency of inorganic mercury, but had no effect on the potency of organic mercury. Our results point to MRP-mediated elimination of inorganic mercury conjugates as a cellular basis for differences in the accumulation and potency of the two major forms of mercury found in marine environments.
authors.affiliation: Laboratory for Biology and Microbial Genetics, Department for Biochemical Engineering, Faculty of Food Technology and Biotechnology, University of Zagreb, 10000 Zagreb, Croatia.
authors.forename: Ivana
authors.initials: I
authors.lastname: Bosnjak
authors.forename: Kevin R
authors.initials: KR
authors.lastname: Uhlinger
authors.forename: Wesley
authors.initials: W
authors.lastname: Heim
authors.forename: Tvrtko
authors.initials: T
authors.lastname: Smital
authors.forename: Jasna
authors.initials: J
authors.lastname: Franekić-Colić
authors.forename: Kenneth
authors.initials: K
authors.lastname: Coale
authors.forename: David
authors.initials: D
authors.lastname: Epel
authors.forename: Amro
authors.initials: A
authors.lastname: Hamdoun
mesh_terms: D000818:Animals; D001692:Biological Transport; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000378:metabolism*; D004784:Environmental Monitoring; D005978:Glutathione / Q000378:metabolism; D007287:Inorganic Chemicals / Q000378:metabolism*; D042541:Intracellular Space / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000378:metabolism*; D008628:Mercury / Q000378:metabolism*; D008938:Mitosis; D009930:Organic Chemicals / Q000378:metabolism*; D012617:Sea Urchins / Q000166:cytology / Q000196:embryology* / Q000378:metabolism*
chemical_list: D007287:Inorganic Chemicals; D026901:Membrane Transport Proteins; D009930:Organic Chemicals; D008628:Mercury; D005978:Glutathione