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The DNA synthesis of leukemic (L2C) guinea pig B lymphocytes involves a permanent activation of protein kinase C without corresponding phosphoinositide hydrolysis.
- Source :
-
Leukemia research [Leuk Res] 1989; Vol. 13 (7), pp. 583-94. - Publication Year :
- 1989
-
Abstract
- L2C B lymphocytes have a constant high DNA synthesis due to their continuous proliferative state. The addition of polymyxin B (PmB), a rather selective inhibitor of protein kinase C, stopped (3H)thymidine incorporation with an IC50 of 10 microM when added 18 h before measuring DNA synthesis. Interestingly, PmB inhibition of DNA synthesis was suppressed when 4 nM 12-O-tetradecanoylphorbol-13-acetate was added along with PmB, indicating that PmB may act through inhibition of protein kinase C. In the node and spleen lymphocytes of normal guinea pigs, protein kinase C activity was entirely cytosolic and was eluted at 0.12 M NaCl when adsorbed on DEAE-cellulose. In L2C leukemic lymphocytes, total protein kinase C activity was of the same order of magnitude, but 20% of it was associated with the membrane fraction. The lipid-dependent activity, eluted at 0.12 M NaCl from cytosolic and membrane fractions, was suppressed by staurosporine with an IC50 of 10-40 nM and by polymyxin B with an IC50 of 2-6 microM. Phosphoinositide metabolism was studied in the transformed cells. Incorporation of 32Pi into polyphosphoinositides was considerable, whereas much more time was required for a tiny incorporation of inositol. We detected no release of radioactive inositol triphosphate. Taken together, these results suggest that protein kinase C function is indispensible for triggering L2C leukemic lymphocyte proliferation. The causes of this permanent activation merit further investigation.
- Subjects :
- Animals
B-Lymphocytes enzymology
Burkitt Lymphoma enzymology
Burkitt Lymphoma genetics
Cell Line
Chromatography, DEAE-Cellulose
Cyclic AMP antagonists & inhibitors
Enzyme Activation
Female
Guinea Pigs
Hydrolysis
Phosphatidic Acids biosynthesis
Phosphatidylinositol 4,5-Diphosphate
Phosphatidylinositols biosynthesis
Phospholipids analysis
Protein Kinase C antagonists & inhibitors
Tumor Cells, Cultured enzymology
Tumor Cells, Cultured metabolism
B-Lymphocytes metabolism
Burkitt Lymphoma metabolism
DNA biosynthesis
Phosphatidylinositols metabolism
Protein Kinase C metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 0145-2126
- Volume :
- 13
- Issue :
- 7
- Database :
- MEDLINE
- Journal :
- Leukemia research
- Publication Type :
- Academic Journal
- Accession number :
- 2548042
- Full Text :
- https://doi.org/10.1016/0145-2126(89)90125-2