Involvement of polyamines in B cell receptor-mediated apoptosis: spermine functions as a negative modulator.
The B cell lymphoma WEHI231 has been used as a model for studying clonal deletion of B cells on the basis of its ability to undergo growth arrest and apoptosis by B cell antigen receptor (BCR) cross-linking. To comprehensively analyze the genes involved in BCR-mediated apoptosis, we applied the technique of serial analysis of gene expression (SAGE) to WEHI231. Comparison of expression patterns revealed that BCR cross-linking caused coordinate changes in the expression of genes involved in polyamine metabolism. Polyamines are ubiquitous compounds required for cell proliferation and homeostasis. The coordinate expression of the polyamine-related genes was confirmed by semiquantitative reverse transcriptase-polymerase chain reaction analysis. During apoptosis, the genes involved in polyamine biosynthesis were downregulated, whereas those involved in polyamine catabolism were upregulated, suggesting that intracellular polyamines play a role in BCR-mediated apoptosis. Levels of intracellular putrescine, spermidine, and spermine were reduced after BCR cross-linking. These effects were prevented by concurrent CD40 stimulation, which blocked BCR-mediated apoptosis. Furthermore, addition of spermine could repress the BCR-mediated apoptosis by attenuating the mitochondrial membrane potential (Deltapsim) loss and activation of caspase-7 induced by BCR signaling. These findings strongly suggest that polyamine regulation is involved in apoptosis during B cell clonal deletion.
Nitta
T
T
Department of Microbiology and Molecular Virology, Tokyo Medical and Dental University, Tokyo, Japan.
Igarashi
K
K
Yamashita
A
A
Yamamoto
M
M
Yamamoto
N
N
D000818:Animals; D017209:Apoptosis; D001402:B-Lymphocytes / Q000166:cytology / Q000378:metabolism; D019013:CD40 Antigens / Q000378:metabolism; D015870:Gene Expression; D007424:Intracellular Fluid / Q000378:metabolism; D051379:Mice; D011947:Receptors, Antigen, B-Cell / Q000378:metabolism*; D013096:Spermine / Q000378:metabolism / Q000502:physiology*
D019013:CD40 Antigens; D011947:Receptors, Antigen, B-Cell; D013096:Spermine