Involvement of Histone Phosphorylation in Thymocyte Apoptosis by Protein Phosphatase Inhibitors

Incubation of rat thymocytes with the inhibitors of protein phosphatase such as calyculin A and okadaic acid resulted in an increase in DNA fragmentation. These effects were dependent on the concentration of the inhibitors and the incubation time. Analyses of the fragmented DNA revealed the producti...

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Bibliographic Details
Published in:IUBMB life 1999-07, Vol.48 (1), p.79-83
Main Authors: Lee, Eibai, Nakatsuma, Akira, Hiraoka, Rikako, Ishikawa, Eriko, Enomoto, Riyo, Yamauchi, Aiko
Format: Article
Language:English
Subjects:
Apoptosis
Chromatin
Dna Fragmentation
Histone Phosphorylation
Protein Phosphatase Inhibitors
Thymocyte
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Summary:Incubation of rat thymocytes with the inhibitors of protein phosphatase such as calyculin A and okadaic acid resulted in an increase in DNA fragmentation. These effects were dependent on the concentration of the inhibitors and the incubation time. Analyses of the fragmented DNA revealed the production of 50 kbp of DNA and a 180 bp DNA ladder. In addition, a laser scanning microscopic analysis showed that these compounds caused nuclear condensation. Thus, these results demonstrated that protein phosphatase inhibitors induced thymocyte apoptosis. The inhibitors of protein phosphatase increased the phosphorylation of proteins of 15 kDa. The phosphorylation of proteins preceded the DNA fragmentation induced by these inhibitors. Judging from acetic acid urea Triton X‐100 gel electrophoresis, the phosphorylated proteins were histone H1 and H2A/H3. Therefore, these results suggest that phosphorylation of histones triggers the DNA fragmentation of thymocytes undergoing apoptosis.
ISSN:1521-6543
1521-6551
DOI:10.1080/713803462