Phosphorylation of ribosomal protein S6 and its regulation during differentiation of human leukemic cells.
10.3346/jkms.1993.8.6.413
- Author:
In Soon KIM
1
;
Sang Bok LEE
;
Kyu Chul CHO
Author Information
1. Department of Pharmacology, Catholic University Medical College, Seoul, Korea.
- Publication Type:Original Article ; Research Support, Non-U.S. Gov't
- Keywords:
Differentiation;
S6;
TPA;
Protein kinase C;
Protein tyrosine kinase
- MeSH:
Cell Differentiation;
Humans;
Leukemia/*metabolism/pathology;
Macrophage Colony-Stimulating Factor/pharmacology;
Phosphorylation;
Protein Kinase C/physiology;
Protein-Tyrosine Kinases/physiology;
Ribosomal Protein S6;
Ribosomal Proteins/*metabolism;
Tetradecanoylphorbol Acetate/pharmacology;
Tumor Cells, Cultured
- From:Journal of Korean Medical Science
1993;8(6):413-419
- CountryRepublic of Korea
- Language:English
-
Abstract:
We attempted to study the role of protein tyrosine kinase (PTK) and protein kinase C (PKC) in the cascade of phosphorylation of ribosomal protein S6 during differentiation of leukemic cells (HL-60, THP-1, and RWLeu-4). Neither activation nor inhibition of colony stimulating factor-1 (CSF-1) receptor's PTK activity with CSF-1 or genistein respectively affected the phosphorylation of S6. However, vanadate which is a protein tyrosine phosphatase (PTP) inhibitor showed enhancement of S6 phosphorylation. Dimethylsulfoxide which does not affect either PTK or PKC demonstrated no change in S6 phosphorylation. PKC activation by acute 12-0-tetradecanoyl phorbol-13-acetate (TPA) treatment induced monocytic differentiation and S6 phosphorylation. Surprisingly, the more prominent phosphorylation of S6 protein was observed in PKC-depleted cells by prolonged TPA treatment. Our results suggest that PTK/PTP play a lesser role in S6 phosphorylation of HL-60 cells than PKC does. In addition, two different mechanisms seem to be involved in TPA-induced S6 phosphorylation during HL-60 differentiation: PKC activation by acute TPA treatment and PKC depletion which may lead to the synthesis of some endogenous protein responsible for the differentiation by chronic TPA treatment.
