Polyamine transport systems in the LLC-PK1 renal epithelial established cell line

Polyamine regulation of Na+/glucose symporter expression in LLC‐PK1 cells

“…In the kidney, increases in polyamines and in activity of ornithine decarboxylase (ODC), the rate-limiting first step in polyamine biosynthesis, accompany renal hypertrophy (Humphreys et al, 1988). Polyamines are taken up into LLC-PK, cells by both Na+-dependent and -independent transporters (DeSmedt et al, 1989;Hauser and Cook, 1990;Parys et al, 1990). In the present study, we demonstrate that addition of polyamines or their analogs to a clonal line of LLC-PK, cells results in a dramatic decrease in Na+/glucose symporter expression.…”

Regulation of polyamine transport in Chinese hamster ovary cells

“…One of these has a higher affinity for terminal aminobutyl groups, is sodium dependent, interacts with the toxic herbicide paraquat, and demonstrated a faster regulatory response to elevated polyamines while the other has a greater affinity for terminal aminopropyl groups, is sodium independent, is insensitive to paraquat and is relatively less sensitive to increased intracellular polyamine levels (Feige and Chambaz, 1985;Byers et al, 1987;Rannels et al, 1989;De Smedt et al, 1989;Kumagi et al, 1989;Saunders et al, 1989;Nuttall et al, 1990). The apparent differential regulation of these two systems deserves further study and could be related to the greater affinity of a critical protein for spermine as opposed to putrescine.…”

Recent advances in the molecular biology of metazoan polyamine transport

“…"Taking baby steps: the riddle of the identity of polyamine permeases"). A number of reports have provided evidence for at least two classes of polyamine permeases, often on the basis of the apparent "Na + dependence" discussed above (De Smedt et al 1989;Rannels et al 1989;Nicolet et al 1990;Parys et al 1990;Seiler et al 1996;Seiler and Dezeure 1990). Since the latter property more likely corresponds to the differential degree of transport inhibition by high concentrations of monovalent cations, the mammalian PTSs can be divided into (a) putrescine or diamine-preferential transporters that are more monocation-sensitive and (b) spermidine/spermine-or true polyamine-preferential transporters that are less sensitive to monovalent cations (Seiler and Dezeure 1990).…”

“…This series exhibits two peaks of maximal affinity at n = 4 (putrescine) and 7-8, with the particular distinction that diaminoheptane and diaminooctane are excellent competitors of spermidine transport, unlike putrescine (Porter and Bergeron 1983;Bergeron and Seligsohn 1986). Thus, by analogy with the prokaryotic PotABCD ABC permease that can use both putrescine and spermidine as substrates via interaction with partially overlapping residues in the substrate binding site of PotD (Kashiwagi et al 1996), a single polyamine permease type might in fact be responsible for the uptake of both diamines and polyamines in mammalian cells (Feige and Chambaz 1985;Gawel-Thompson and Greene 1988;De Smedt et al 1989). This hypothesis would also be consistent with the fact that all known mammalian cell mutants deficient in spermidine or spermine transport are also deficient in putrescine transport (Seiler 2003), and transfection of human genomic DNA invariably restores transport activity for all three substrates .…”