Interleukin-6-induced tyrosine phosphorylation of multiple proteins in murine hematopoietic lineage cells.

Interleukin-6 (IL-6) is a multifunctional cytokine playing various roles in the immune system, hematopoiesis and acute phase reactions. To elucidate the intracellular signal transduction mechanism through the IL-6 receptor, we investigated IL-6-induced protein tyrosine phosphorylation in murine hematopoietic cell lines, BAFm130 and Y6. IL-6 stimulated tyrosine phosphorylation of multiple cellular proteins, such as gp130, an IL-6 signal transducer; Jak family of the cytoplasmic tyrosine kinases; and the latent cytoplasmic signal transducer and activator of transcription. We showed that the pattern of these tyrosine-phosphorylated molecules was different between BAFm130 and Y6 cells on which IL-6 exhibited different biological activities.