Abstract |
Protein phosphorylation plays an important role in signal transduction, but its involvement in apoptosis still remains unclear. In this report, the p53-null human leukemia HL60 cells were used to investigate phosphorylation and degradation of lamin B during apoptosis. We found that lamin B was phosphorylated within 1 h after addition of the DNA topoisomerase I inhibitor, camptothecin, and that lamin B phosphorylation preceded lamin B degradation and DNA fragmentation. Using a cell-free system we also found that cytosol from camptothecin-treated cells induced lamin B phosphorylation and degradation in isolated nuclei from untreated HL60 cells. Lamin B phosphorylation was prevented by the protein kinase C (PKC) inhibitor 7-hydroxystaurosporine (UCN-01) but not by the Cdc2 inhibitor, flavopiridol. Phosphorylation of lamin B was inhibited by immunodepletion of PKCalpha from activated cytosol and was restored by addition of purified PKCalpha. PKCalpha activity also increased rapidly as lamin B was phosphorylated after initiation of the apoptotic response in HL60 cells. These data suggest that lamin B is phosphorylated by PKCalpha and proteolyzed before DNA fragmentation in HL60 cells undergoing apoptosis.
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Authors | T Shimizu, C X Cao, R G Shao, Y Pommier |
Journal | The Journal of biological chemistry
(J Biol Chem)
Vol. 273
Issue 15
Pg. 8669-74
(Apr 10 1998)
ISSN: 0021-9258 [Print] United States |
PMID | 9535842
(Publication Type: Journal Article)
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Chemical References |
- Coumarins
- Isocoumarins
- Isoenzymes
- Lamin Type B
- Lamins
- Nuclear Proteins
- Peptide Fragments
- Serine Proteinase Inhibitors
- Topoisomerase I Inhibitors
- Tumor Suppressor Protein p53
- 3,4-dichloroisocoumarin
- PRKCA protein, human
- Protein Kinase C
- Protein Kinase C-alpha
- Camptothecin
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Topics |
- Amino Acid Sequence
- Apoptosis
(drug effects)
- Camptothecin
(pharmacology)
- Cell Nucleus
(metabolism)
- Coumarins
(pharmacology)
- Cytosol
(metabolism)
- DNA Fragmentation
- HL-60 Cells
(cytology, metabolism)
- Humans
- Isocoumarins
- Isoenzymes
(metabolism)
- Kinetics
- Lamin Type B
- Lamins
- Molecular Sequence Data
- Nuclear Proteins
(chemistry, metabolism)
- Peptide Fragments
(chemistry)
- Phosphorylation
- Protein Kinase C
(metabolism)
- Protein Kinase C-alpha
- Protein Structure, Secondary
- Serine Proteinase Inhibitors
(pharmacology)
- Time Factors
- Topoisomerase I Inhibitors
- Tumor Suppressor Protein p53
(deficiency)
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