Open AccessPhosphorylation of ribosomal protein S6 and its regulation during differentiation of human leukemic cells
Author(s) -
In Soon Kim,
Sang Bok Lee,
Kyu Chul Cho
Publication year - 1993
Publication title -
journal of korean medical science/journal of korean medical science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.743
H-Index - 66
eISSN - 1598-6357
pISSN - 1011-8934
DOI - 10.3346/jkms.1993.8.6.413
Subject(s) - phosphorylation , ribosomal protein s6 , protein kinase c , protein phosphorylation , tyrosine phosphorylation , protein tyrosine phosphatase , kinase , ribosomal s6 kinase , biology , microbiology and biotechnology , cellular differentiation , protein kinase a , chemistry , biochemistry , p70 s6 kinase 1 , protein kinase b , gene
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.