IL-6-induced calmodulin-dependent protein phosphorylation in B9 hybridoma cells.
The addition of IL-6 to the IL-6-dependent B9-55 hybridoma cells starved for IL-6 for 16 h induced an increased phosphorylation of a 25-kda protein (p25). Phosphorylation of p25 was IL-6 dependent and maximal at 5 min after IL-6 stimulation. Phosphorylation of p25 was inhibited by N-(6-aminohexyl)-5-chloro-1-naphthalene sulfonamide (W-7), an inhibitor of calmodulin-dependent protein kinase, but not by tyrphostin nor ionomycin. When enolase was used as an exogenous substrate, similar results were obtained. Furthermore, calmodulin stimulated p25 phosphorylation in vitro. IL-6-starved B9 hybridoma cells synthesized DNA at 9 to 12 h after addition of IL-6. Preincubation of cells with W-7 before IL-6 stimulation blocked DNA synthesis. Similar effects were observed when cells were preincubated with tyrphostin or ionomycin but to a lesser extent. The concentrations of W-7 required for blocking p25 phosphorylation and DNA synthesis correlated relatively well. These results suggest that an IL-6-inducible calmodulin-dependent protein kinase is involved in IL-6 signal transduction, including p25 phosphorylation and B9 hybridoma proliferation.
Choi
I
I
Immunology Research Laboratory, Genetic Engineering Research Institute, KIST, Taejon, Republic of Korea.
Na
W J
WJ
Kang
H S
HS
Pyun
K H
KH
D000818:Animals; D002147:Calmodulin / Q000494:pharmacology*; D002455:Cell Division; D002478:Cells, Cultured; D006825:Hybridomas / Q000378:metabolism*; D015850:Interleukin-6 / Q000494:pharmacology*; D051379:Mice; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation
D002147:Calmodulin; D015850:Interleukin-6; D010750:Phosphoproteins