Nonmetabolizable glucose analogues and ornithine decarboxylase expression in LLC-PK1 cells.
This report examines the effect of nonmetabolizable glucose analogues on ornithine decarboxylase (ODC) activity in LLC-PK1 cells. The addition of Na(+)-dependent cotransported glucose analogues, 1-O-methyl-alpha-D-glucopyranoside (alpha-MDG) and 1-O-methyl-beta-D-glucopyranoside, to Earle's balanced salt solution minus glucose (EBSS-G) increased ODC activity five- to sevenfold above basal levels. The passive carrier-mediated transported glucose analogue 3-O-methyl-D-glucopyranose had very little effect on enzyme activity. alpha-MDG increased ODC activity in quiescent but not growing cells. ODC activity increased as a function of both the incubation time in EBSS-G + alpha-MDG and the concentration of alpha-MDG in EBSS-G. Phlorizin significantly reduced the level of enzyme activity induced by alpha-MDG. ODC expression by alpha-MDG was reduced in cells incubated in hypertonic EBSS-G + alpha-MDG. Enzyme activity, in the absence of extracellular organic substrates, was markedly elevated in cells incubated in hypotonic media. It is suggested that an influx of Na+ and/or an increase in cell volume elevates one or more signal transducers that regulate ODC expression.
Lundgren
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DW
Department of Pediatrics, Case Western Reserve Univesity, Cleveland, Ohio 44109.
Vacca
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CV
D019325:3-O-Methylglucose; D000818:Animals; D002460:Cell Line; D003470:Culture Media; D007700:Kinetics; D008757:Methylglucosides / Q000494:pharmacology*; D009955:Ornithine Decarboxylase / Q000378:metabolism*; D009994:Osmolar Concentration; D010695:Phlorhizin / Q000494:pharmacology
D003470:Culture Media; D008757:Methylglucosides; D019325:3-O-Methylglucose; C027020:methylglucoside; D010695:Phlorhizin; D009955:Ornithine Decarboxylase