TY - JOUR
T1 - Rapid turnover of endogenous endonuclease activity in thymocytes
T2 - Effects of inhibitors of macromolecular synthesis
AU - McConkey, David J.
AU - Hartzell, Pia
AU - Orrenius, Sten
N1 - Funding Information:
We thank Sten Thorold for preparing the illustrations. This study was supportedb y grants from the Swedish Medical Research Council (Project No. 03X-2471) and the Karolinska Institutet.
Copyright:
Copyright 2014 Elsevier B.V., All rights reserved.
PY - 1990/4
Y1 - 1990/4
N2 - Previous work has shown that inhibitors of protein or mRNA synthesis block endonuclease activation in thymocytes undergoing programmed cell death. In the present study we used isolated nuclei to investigate the effects of cycloheximide and actinomycin D, inhibitors of protein and mRNA synthesis, respectively, on endogenous endonuclease activity in thymocytes. We observed a rapid loss of Ca2+-dependent endonuclease activity in nuclei isolated from thymocytes treated with these inhibitors. In contrast, pretreatment of cells with antipain and leupeptin, inhibitors of proteases, prevented the depletion of endonuclease activity in the nuclei, suggesting that proteolysis was involved. The effects of cycloheximide and actinomycin D were mimicked by incubating thymocytes with treatments known to exert their effects via activation of protein kinase C. Our results suggest that endonuclease activity in thymocyte nuclei undergoes rapid, spontaneous turnover. Agents interfering with macromolecular synthesis may therefore block DNA fragmentation in thymocytes by depleting nuclei of endogenous endonuclease activity.
AB - Previous work has shown that inhibitors of protein or mRNA synthesis block endonuclease activation in thymocytes undergoing programmed cell death. In the present study we used isolated nuclei to investigate the effects of cycloheximide and actinomycin D, inhibitors of protein and mRNA synthesis, respectively, on endogenous endonuclease activity in thymocytes. We observed a rapid loss of Ca2+-dependent endonuclease activity in nuclei isolated from thymocytes treated with these inhibitors. In contrast, pretreatment of cells with antipain and leupeptin, inhibitors of proteases, prevented the depletion of endonuclease activity in the nuclei, suggesting that proteolysis was involved. The effects of cycloheximide and actinomycin D were mimicked by incubating thymocytes with treatments known to exert their effects via activation of protein kinase C. Our results suggest that endonuclease activity in thymocyte nuclei undergoes rapid, spontaneous turnover. Agents interfering with macromolecular synthesis may therefore block DNA fragmentation in thymocytes by depleting nuclei of endogenous endonuclease activity.
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U2 - 10.1016/0003-9861(90)90261-V
DO - 10.1016/0003-9861(90)90261-V
M3 - Article
C2 - 2157360
AN - SCOPUS:0025276090
SN - 0003-9861
VL - 278
SP - 284
EP - 287
JO - Archives of Biochemistry and Biophysics
JF - Archives of Biochemistry and Biophysics
IS - 1
ER -