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Calcium‐activated DNA fragmentation kills immature thymocytes

Calcium‐activated DNA fragmentation kills immature thymocytes Glucocorticoid hormones kill immature thymocytes by activating a self‐destructive process that involves extensive DNA fragmentation. It has been demonstrated that thymocyte suicide is dependent on an early, sustained increase in cytosolic Ca2+ concentration, and new protein synthesis, but the biochemical lesion that leads to cell death has not been established. To determine whether endonuclease activation or activation of another Ca2+‐de‐pendent process could mediate cell killing, we treated thymocytes with the glucocorticoid methylprednisolone in the presence of inhibitors of various Ca2+‐dependent degradative enzymes. The role of poly(ADP‐ribose) polymerase, an enzyme known to be activated by DNA damage, was also assessed. Glucocorticoid‐induced chromatin cleavage and cell killing were blocked by the endonuclease inhibitor aurintricarboxylic acid, whereas inhibitors of other Ca2+‐dependent degradative processes or of poly(ADP‐ribose) polymerase did not abrogate cell death. In addition, stimulation of thymocyte DNA fragmentation by the Ca2+ ionophore A23187 resulted in cell killing that could be blocked by the endonuclease inhibitor. Together, our results suggest that thymocyte suicide is caused by extensive Ca2+‐stimulated DNA fragmentation.— McConkey, D. J.; Hartzell, P.; Nicotera, P.; Orrenius, S. Calcium‐activated DNA fragmentation kills immature thymocytes. FASEB J. 3: 1843‐1849; 1989. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The FASEB journal Wiley

Calcium‐activated DNA fragmentation kills immature thymocytes

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References (35)

Publisher
Wiley
Copyright
© Federation of American Societies for Experimental Biology
ISSN
0892-6638
eISSN
1530-6860
DOI
10.1096/fasebj.3.7.2497041
Publisher site
See Article on Publisher Site

Abstract

Glucocorticoid hormones kill immature thymocytes by activating a self‐destructive process that involves extensive DNA fragmentation. It has been demonstrated that thymocyte suicide is dependent on an early, sustained increase in cytosolic Ca2+ concentration, and new protein synthesis, but the biochemical lesion that leads to cell death has not been established. To determine whether endonuclease activation or activation of another Ca2+‐de‐pendent process could mediate cell killing, we treated thymocytes with the glucocorticoid methylprednisolone in the presence of inhibitors of various Ca2+‐dependent degradative enzymes. The role of poly(ADP‐ribose) polymerase, an enzyme known to be activated by DNA damage, was also assessed. Glucocorticoid‐induced chromatin cleavage and cell killing were blocked by the endonuclease inhibitor aurintricarboxylic acid, whereas inhibitors of other Ca2+‐dependent degradative processes or of poly(ADP‐ribose) polymerase did not abrogate cell death. In addition, stimulation of thymocyte DNA fragmentation by the Ca2+ ionophore A23187 resulted in cell killing that could be blocked by the endonuclease inhibitor. Together, our results suggest that thymocyte suicide is caused by extensive Ca2+‐stimulated DNA fragmentation.— McConkey, D. J.; Hartzell, P.; Nicotera, P.; Orrenius, S. Calcium‐activated DNA fragmentation kills immature thymocytes. FASEB J. 3: 1843‐1849; 1989.

Journal

The FASEB journal – Wiley

Published: May 1, 1989

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