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Properties of a polyamine transporter regulated by antizyme
K Sakata1, K Kashiwagi, K Igarashi
1Faculty of Pharmaceutical Sciences, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan.
Abstract:
The regulation of polyamine transport by antizyme, a protein that is involved in the rapid degradation of ornithine decarboxylase (ODC), was studied in FM3A mouse cells overproducing ODC. Both artificial (Z1) and natural antizymes not only inhibited polyamine uptake but also stimulated polyamine excretion. The properties of the polyamine transporter regulated by antizyme were characterized. The uptake of radiolabelled polyamines was inhibited by excess acetylpolyamines and a protonophore, CCCP (carbonyl cyanide m-chlorophenylhydrazone), whereas the excretion of radiolabelled polyamines was stimulated by unlabelled polyamines, acetylpolyamines and CCCP in the medium. Furthermore, it is shown that polyamines and acetylpolyamines are excreted from cells. On the basis of the results, it is discussed how antizyme regulates polyamine transport negatively.
Insights
Antizyme negatively regulates polyamine transport by inhibiting uptake and stimulating excretion. This study characterizes the polyamine transporter
Area of Science:
- Cellular Biology
- Biochemistry
- Molecular Biology
Background:
- Polyamines are essential for cell growth and proliferation.
- Antizyme regulates ornithine decarboxylase (ODC) degradation, influencing polyamine levels.
- The precise role of antizyme in polyamine transport remains incompletely understood.
Purpose of the Study:
- To investigate the effect of antizyme on polyamine transport in FM3A mouse cells.
- To characterize the properties of the antizyme-regulated polyamine transporter.
Main Methods:
- Overproduction of ODC in FM3A mouse cells.
- Treatment with artificial (Z1) and natural antizymes.
- Measurement of radiolabeled polyamine uptake and excretion.
- Use of acetylpolyamines and CCCP to probe transporter activity.
Main Results:
- Antizymes inhibited polyamine uptake and stimulated polyamine excretion.
- Polyamine transporter activity was modulated by acetylpolyamines and CCCP.
- Evidence suggests active excretion of polyamines and acetylpolyamines from cells.
Conclusions:
- Antizyme plays a crucial role in the negative regulation of polyamine transport.
- Antizyme influences both the influx and efflux of polyamines across the cell membrane.
- Characterization of the antizyme-regulated transporter provides insights into cellular polyamine homeostasis.