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.

Cancer Drug Development Using Drosophila as an in vivo Tool: From Bedside to Bench and Back

“…More specifically, a library of polyamine-anthracene conjugates was found to possess similar PAT selectivity and toxicity profiles in mammalian cell culture and Drosophila imaginal discs. Furthermore, polyamine uptake in Drosophila S2 cells was found to be sensitive to pH in another independent study [97]. That Drosophila could be used for the screening of compounds with known bioavailability was reported in a recent study [22].…”

Molecular characterization of a human cation‐Cl− cotransporter (SLC12A8A, CCC9A) that promotes polyamine and amino acid transport

“…In this work, candidate substrates that might be transported by CCC9a included amino acids (Glu and Asp especially) as also described for other PA carriers (Rinehart and Chen, 1984;Jack et al, 2000;Kashiwagi et al, 1992;Uemura et al, 2005b;Romero-Calderon and Krantz, 2006) as already alluded to above. One could thus predict that CCC9a operates as a PA-amino acid efflux system-preliminary studies have confirmed that PA fluxes in HEK huCCC9a could be elicited in both directions-unless the chemical potential for PA, Glu, and Asp was balanced off by that of another (still unidentified) substrate or the electrical potential.…”

“…Many PA transporters have been shown to promote the comovement of ions and amino acids or to exhibit ion-dependent PA transport activity (Rinehart and Chen, 1984;Jack et al, 2000;Kashiwagi et al, 1992;Kobayashi et al, 1992Kobayashi et al, , 1999Uemura et al, 2005b;Romero-Calderon and Krantz, 2006). As such, we determined whether PA transport activity in stable HEK huCCC9a was affected by such cosubstrates and whether it varied with (PA) according to Michaelian behavior as would be expected it was induced by a carrier system.…”

“…In unicellular species, most PA transporters have been found to operate at the cell surface (multiple authors et al in References) as efflux systems (e.g., TPO1-5) or influx systems (e.g., GAP1p, AGP2, and lmPOT1), catalyzing the movement of one type of PA species preferentially. A number of these transporters have also been ascribed more complex functions such as promoting amino acid or ion translocation in parallel (Rinehart and Chen, 1984;Jack et al, 2000;Kashiwagi et al, 1992;Kobayashi et al, 1992Kobayashi et al, , 1999Uemura et al, 2005b;Romero-Calderon and Krantz, 2006).…”

Polyamine uptake by the intraerythrocytic malaria parasite, Plasmodium falciparum

“…Polyamine uptake has been shown to be temperature-dependent in a variety of cells (Basselin et al, 2000;Fukumoto and Byus, 1996;Romero-Calderon and Krantz, 2006;Soulet et al, 2002).…”