Molecular changes associated with induction of cell death in a human T-cell leukaemia line: putative nucleases identified as histones.
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.
Baxter
G D
GD
Molecular Oncology, Queensland Institute of Medical Research, Brisbane, Australia.
Smith
P J
PJ
Lavin
M F
MF
D000595:Amino Acid Sequence; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D002843:Chromatin / Q000378:metabolism; D004247:DNA / Q000187:drug effects; D003907:Dexamethasone; D004720:Endonucleases / Q000302:isolation & purification / Q000378:metabolism*; D006657:Histones / Q000302:isolation & purification / Q000378:metabolism*; D006801:Humans; D015458:Leukemia, T-Cell / Q000201:enzymology* / Q000378:metabolism / Q000473:pathology; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins / Q000096:biosynthesis; D014407:Tumor Cells, Cultured / Q000201:enzymology / Q000378:metabolism / Q000473:pathology
D002843:Chromatin; D006657:Histones; D009363:Neoplasm Proteins; D003907:Dexamethasone; D004247:DNA; D004720:Endonucleases