Signal transduction pathways activated by ciliary neurotrophic factor and related cytokines.

Neuropoietic cytokines such as ciliary neurotrophic factor, leukemia inhibitory factor, and interleukin-6 are known to be responsible for a wide variety of effects on cells of the immune and nervous systems. The mechanisms by which such diverse effects are regulated and coordinated within cells is of central importance to the understanding of how these molecules function during development. This review discusses the receptor complexes through which neuropoietic cytokines signal and the mechanisms by which activation of specific enzymes such as the Jak family of kinases are transduced into changes of gene expression through molecules such as the Stat proteins. This review also discusses how this JAK-Stat signaling pathway is thought to interact with other known cascades, such as the mitogen-activated protein kinase pathway.