Journal of Biological Chemistry
Volume 283, Issue 44, 31 October 2008, Pages 30341-30350
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Protein Structure and Folding
Ciliary Neurotrophic Factor, Cardiotrophin-like Cytokine, and Neuropoietin Share a Conserved Binding Site on the Ciliary Neurotrophic Factor Receptor α Chain*

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Ciliary neurotrophic factor, cardiotrophin-like cytokine, and neuropoietin are members of the four-helix bundle cytokine family. These proteins signal through a common tripartite receptor composed of leukemia inhibitory factor receptor, gp130, and ciliary neurotrophic factor receptor α. Binding to ciliary neurotrophic factor receptor α occurs through an interaction site located at the C terminus of the cytokine AB loop and αD helix, known as site 1. In the present study, we have generated a model of neuropoietin and identified a conserved binding site for the three cytokines interacting with ciliary neurotrophic factor receptor α. To identify the counterpart of this site on ciliary neurotrophic factor receptor α, its cytokine binding domain was modeled, and the physicochemical properties of its surface were analyzed. This analysis revealed an area displaying properties complementary to the site 1 of ciliary neurotrophic factor, cardiotrophin-like cytokine, and neuropoietin. Based on our computational predictions, residues were selected for their potential involvement in the ciliary neurotrophic factor receptor α binding epitope, and site-directed mutagenesis was carried out. Biochemical, cell proliferation, and cell signaling analyses showed that Phe172 and Glu286 of ciliary neurotrophic factor receptor α are key interaction residues. Our results demonstrated that ciliary neurotrophic factor, cardiotrophin-like cytokine, and neuropoietin share a conserved binding site on ciliary neurotrophic factor receptor α.

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*

This work was supported by Association Française contre les Myopathies Grant 9884 and by the Ciblage Moléculaire et Application Thérapeutique (CIMATH) program of the region Pays de la Loire. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

The on-line version of this article (available at http://www.jbc.org) contains supplemental Fig. 1.

1

Supported by the Angers Agglomeration.