title: Transport of polyamines in Drosophila S2 cells: kinetics, pharmacology and dependence on the plasma membrane proton gradient.
abstract: Polyamine transport activities have been described in diverse multicellular systems, but their bioenergetic mechanisms and molecular identity remain unclear. In the present paper, we describe a high-affinity spermine/spermidine transport activity expressed in Drosophila S2 cells. Ion-replacement experiments indicate that polyamine uptake across the cell membrane is Na+-, K+-, Cl-- and Ca2+-independent, but pH-sensitive. Additional experiments using ionophores suggest that polyamine uptake may be H+-coupled. Pharmacological experiments show that polyamine uptake in S2 cells is selectively blocked by MGBG {methylglyoxal bis(guanylhydrazone) or 1,1'-[(methylethanediylidine)-dinitrilo]diguanidine} and paraquat (N,N-dimethyl-4,4'-bipyridylium), two known inhibitors of polyamine uptake in mammalian cells. In addition, inhibitors known to block the Slc22 (solute carrier 22) family of organic anion/cation transporters inhibit spermine uptake in S2 cells. These data and the genetic tools available in Drosophila will facilitate the molecular identification and further characterization of this activity.
authors.affiliation: Interdepartmental Ph.D. Program in Neuroscience, UCLA, Los Angeles, CA 90095, USA.
authors.forename: Rafael
authors.initials: R
authors.lastname: Romero-Calderón
authors.forename: David E
authors.initials: DE
authors.lastname: Krantz
mesh_terms: D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002118:Calcium / Q000494:pharmacology; D002352:Carrier Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D002460:Cell Line; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism*; D002712:Chlorides / Q000494:pharmacology; D004331:Drosophila melanogaster / Q000166:cytology* / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008935:Mitoguazone / Q000494:pharmacology; D010269:Paraquat / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D018892:Proton-Motive Force / Q000187:drug effects* / Q000502:physiology*; D012964:Sodium / Q000494:pharmacology; D013095:Spermidine / Q000378:metabolism*; D013096:Spermine / Q000378:metabolism*
chemical_list: D002352:Carrier Proteins; D002712:Chlorides; D013096:Spermine; D012964:Sodium; D008935:Mitoguazone; D010269:Paraquat; D011188:Potassium; D002118:Calcium; D013095:Spermidine