Molecular changes associated with induction of cell death in a human T-cell leukaemia line: putative nucleases identified as histones |
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Authors: | G D Baxter P J Smith M F Lavin |
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Affiliation: | Molecular Oncology, Queensland Institute of Medical Research, Brisbane, Australia. |
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Abstract: | Following treatment of the human T-cell leukaemia line, CEM-C7, with the glucocorticoid, dexamethasone, a rapid decrease in viability occurred after 40 h which coincided with fragmentation of DNA in these cells. A similar pattern of DNA fragmentation was observed when these cells were gamma-irradiated or treated with cycloheximide. Distinct morphological changes occurred after treatment, indicating a form of cell death, regulated from within, termed apoptosis. A set of nuclear proteins ranging in size from 10-18 kDa appeared by 40 h following treatment with dexamethasone. Treatment of cells with gamma-irradiation or cycloheximide also produced the same protein pattern. This set of proteins, and a doublet approximately 55 kDa in size, had apparent nuclease activity which was not observed in untreated cells. However, protein microsequencing of these bands in the 10-18 kDa region revealed that they were histone proteins. These results cast doubt on a recent report which provided evidence that these proteins were induced nucleases. |
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