The interleukin-6 signal transducer, gp130, functioning in immune, hematopoietic, and neural systems]

Functional pleiotropy and redundancy are characteristic features of cytokines. To understand the signaling mechanisms of such cytokines, we have proposed a two-chain interleukin-6 receptor (IL-6-R) model: IL-6 triggers the association of a ligand-binding chain (IL-6-R) and a non-binding signal transducer (gp130) to form a high-affinity receptor complex, causing transmission of the signal by the cytoplasmic portion of gp130. This model would explain the functional redundancy of cytokines if we were to assume that gp130 interacts with several different receptor chains. Here we present data indicating that gp130 functions as a common signal transducer for IL-6, oncostatin M (OM), leukemia inhibitory factor (LIF), and ciliary neurotrophic factor (CNTF). We show that anti-gp130 monoclonal antibodies completely block the biological responses induced by all of these factors. Since LIF functions as a cholinergic differentiation factor in nerve cells as does CNTF, these results suggest that gp130 may also play a role in the neural system.