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Expression of polyamine transporter activity during B lymphocyte cell cycle progression
M DeBenedette1, J W Olson, E C Snow
1Department of Microbiology and Immunology, University of Kentucky Medical Center, Lexington 40536-0084.
Journal of Immunology (Baltimore, Md. : 1950)
|May 15, 1993
Summary
Resting B cells increase polyamine levels upon cell cycle entry, partly via ornithine decarboxylase. They then actively transport extracellular polyamines, suggesting an alternative source to support B cell activation and proliferation.
Area of Science:
- Immunology
- Cell Biology
- Biochemistry
Background:
- B cell activation involves increased cellular polyamine levels.
- Ornithine decarboxylase activity contributes to polyamine elevation but wanes post-stimulation.
- An alternative polyamine source is hypothesized for sustained B cell activation.
Purpose of the Study:
- To investigate the mechanism of polyamine acquisition by B cells during cell cycle progression.
- To determine if B cells transport extracellular polyamines.
- To characterize the nature of polyamine transporters in activated B cells.
Main Methods:
- Stimulation of B cell cycle progression using PMA, ionomycin, and T helper (Th) cells.
- Measurement of extracellular polyamine transport activity.
- Characterization of transport kinetics, energy dependence, and ligand specificity.
Main Results:
- B cells initiate extracellular polyamine transport upon entering the G1 cell cycle stage.
- Transport is induced by various stimuli, including Th cell help.
- Transport is energy-dependent, temperature-sensitive, and exhibits characteristics of at least two transporter types: one low-affinity for putrescine/spermidine, and one high-affinity selective for spermidine.
Conclusions:
- B cells utilize both endogenous synthesis and extracellular uptake of polyamines for cell cycle progression.
- The induction of polyamine transport is a key event in Th cell-mediated B cell activation.
- Characterization of polyamine transporters provides insights into the biochemical regulation of B cell proliferation.