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Mol. Cell. Biol., Feb 1995, 932-942, Vol 15, No. 2
R Fotedar, J Flatt, S Gupta, RL Margolis, P Fitzgerald, H Messier and A Fotedar
Developing thymocytes and some T-cell hybridomas undergo activation-
dependent programmed cell death. Although recent studies have identified
some critical regulators in programmed cell death, the role of cell cycle
regulation in activation-induced cell death in T cells has not been
addressed. We demonstrate that synchronized T-cell hybridomas, irrespective
of the point in the cell cycle at which they are activated, stop cycling
shortly after they reach G2/M. These cells exhibit the diagnostic
characteristics of apoptotic cell death. Although p34cdc2 levels are not
perturbed after activation of synchronously cycling T cells, cyclin B- and
p34cdc2-associated histone H1 kinase activity is persistently elevated.
This activation-dependent induction of H1 kinase activity in T cells is
associated with a decrease in the phosphotyrosine content of p34cdc2. We
also demonstrate that transient inappropriate coexpression of cyclin B with
p34cdc2 induces DNA fragmentation in a heterologous cell type. Finally, in
T cells, cyclin B-specific antisense oligonucleotides suppress activation-
induced cell death but not cell death induced by exposure to dexamethasone.
We therefore conclude that a persistent elevation of the level of cyclin B
kinase is required for activation-induced programmed T-cell death.
Copyright © 1995, American Society for Microbiology
Activation-induced T-cell death is cell cycle dependent and regulated by cyclin B
Institut de Biologie Structurale J.-P. Ebel, Grenoble, France.
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