Solution Structure of the C-terminal Domain of the Ciliary Neurotrophic Factor (CNTF) Receptor and Ligand Free Associations among Components of the CNTF Receptor Complex

Abstract

The functional receptor complex of ciliary neurotrophic factor (CNTF), a member of the gp130 family of cytokines, is composed of CNTF, the CNTF receptor ␣ (CNTFR), gp130, and the leukemia inhibitory factor receptor (LIFR). However, the nature of the receptor-mediated interactions in this complex has not yet been resolved. To address this issue we have determined the solution structure of the C-terminal or BC domain of CNTFR and studied the interactions of CNTFR with LIFR and gp130. We reported previously that the membrane distal cytokine-binding domain (CBD1) of LIFR could interact in vitro with soluble CNTFR (sCNTFR) in the absence of CNTF. Here we show that the CBD of human gp130 can also bind in vitro to sCNTFR in the absence of CNTF. In addition, the gp130 CBD could compete with the LIFR CBD1 for the binding of sCNTFR. Substitution of residues in the gp130 CBD, the LIFR CBD1, and the CNTFR BC domain that are expected to be involved in receptor-receptor interactions significantly reduced their interactions. An NMR chemical shift perturbation study of the interaction between the BC domains of CNTFR and gp130 further mapped the interaction surface. These data suggest that both the gp130 CBD and the LIFR CBD1 interact with CNTFR in a similar way and provide insights into the nature of the CNTF receptor complex.

Leukemia Inhibitory Factor Receptor Signaling Negatively Modulates Nerve Growth Factor-induced Neurite Outgrowth in PC12 Cells and Sympathetic Neurons

“…In the present study, PC12 cells stably expressing AS-LIFR extend short protrusions even without NGF treatment. The less pronounced basal level of neurite initiation observed in DN-LIFR PC12 cells might be because of the incomplete blockade of LIFR signaling or alternatively, different receptorreceptor interactions on the cell surface based on the formation of ligand-free dimers between CNTFR and gp130/LIFR (41,42). The enhanced Rac1 activity observed in AS-LIFR and DN-LIFR cells is consistent with the central tenet that Rac1 activity plays a critical role in the initiation of neurite outgrowth.…”

LIF in the regulation of T-cell fate and as a potential therapeutic

“…24 Overall, it is likely that each of the alternative forms of LIF serves distinct and biologically significant functions. 25 As discussed later, by varied expression levels of LIF-M in different tissues in the body, the micro-environment of T cells in those tissues will be influenced by the combination of LIF-M plus LIF-D. 27 Ligand-specific utilisation of gp130-related receptors [28][29][30][31] and the exchangeable nature of the receptor modules 32 contribute to regulation of LIF signalling at the receptor level. Cross-regulation between downstream pathways has recently been discussed by Niwa et al, 33 here in the context of embryonic stem cells but likely to also apply in principle to other cell types especially those showing epigenetic plasticity during developmental differentiation.…”

Crystal Structures of the Pro-Inflammatory Cytokine Interleukin-23 and Its Complex with a High-Affinity Neutralizing Antibody

“…[8][9][10] The molecular structures of many cytokinereceptor systems are already well known, including several members of the small family of heterodimeric cytokines. Accordingly, the structures for gp130, 11 the C-terminal domain of ciliary neurotrophic factor receptor, 12 and the prototype IL-12 ligand 13 have all been reported as either X-ray or NMR structures. The p35 subunit of IL-12 is a typical four-helix-bundle cytokine sharing homology with IL-6 and granulocyte colony-stimulating factor; it is disulfide linked to the p40 subunit through a pair *Corresponding author.…”