Acquiring signalling specificity from the cytokine receptor gp130.

Repeated use of a relatively small number of intracellular signalling molecules specifies tissue- and cell-type-specific responses to pleiotropic-acting growth factors and cytokines. Currently, gaining a better understanding of these mechanisms is a major challenge. The IL-6 family of cytokines shares a common receptor subunit called gp130. Phenotypic comparisons of mice with amino acid knock-in substitutions that disable individual signalling modules in gp130, with knockout mice lacking ligand-specific gp130 activation or transgenic mice with constitutive gp130 activation, has led to the identification of two molecular mechanisms. One mechanism is based on differential target-gene responsiveness to signalling threshold levels transduced by either the STAT1/3 or the SHP2/ERK cascade, which are under reciprocal negative regulation and together account for the majority of intracellular gp130 signalling. The second mechanism is based on the capacity of certain cell types to integrate the often-conflicting information transduced by these two pathways, and to prevent pathological responses.