Regulation of polyamine transport in Chinese hamster ovary cells

✍ Scribed by Timothy L. Byers; Anthony E. Pegg

• Publisher: John Wiley and Sons
• Year: 1990
• Tongue: English
• Weight: 875 KB
• Volume: 143
• Category: Article
• ISSN: 0021-9541
• DOI: 10.1002/jcp.1041430309

✦ Synopsis

Control Chinese hamster ovary (CHO) cells and mutant CHO cells lacking ornithine decarboxylase activity (CHODC-) were used to study the regulation of polyamine uptake. It was found that the transport system responsible for this uptake was regulated by intracellular polyamine levels and that this regulation was responsible for the maintenance of physiological intracellular levels under extreme conditions such as polyamine deprivation or exposure to exogenous polyarnines. Polyamine transport activity was enhanced by decreases in polyamine content produced either by inhibition of ornithine decarboxylase with a-difluoromethylornithine in CHO cells or via polyamine starvation of CHODCcells. The provision of exogenous polyamines resulted in rapid and large increases in intracellular polyarnine content followed by decreased polyamine transport activity. Soon after this decrease in uptake activity, intracellular polyarnine levels then fell to near control values. Cells grown in the presence of exogenous polyamines maintained intracellular polyarnine levels at values similar to those of control cells. Protein synthesis was necessary for the increase in transport in response to polyamine depletion, but appeared to play no role in decreasing polyamine transport. Bis(ethyl1 polyamine analogues mimicked polyamines in the regulation of polyamine transport but this process was relatively insensitive to regulation by methylglyoxal bis(guany1 hydrazone), a spermidine analogue known to enter cells via this transport system and to accumulate to very high levels.