The amino acid exchange R28E in ciliary neurotrophic factor (CNTF) abrogates interleukin-6 receptor-dependent but retains CNTF receptor-dependent signaling via glycoprotein 130 (gp130)/leukemia inhibitory factor receptor (LIFR).

Abstract

Ciliary neurotrophic factor (CNTF) is a neurotrophic factor with therapeutic potential for neurodegenerative diseases. Moreover, therapeutic application of CNTF reduced body weight in mice and humans. CNTF binds to high or low affinity receptor complexes consisting of CNTFR·gp130·LIFR or IL-6R·gp130·LIFR, respectively. Clinical studies of the CNTF derivative Axokine revealed intolerance at higher concentrations, which may rely on the low-affinity binding of CNTF to the IL-6R. Here, we aimed to generate a CNTFR-selective CNTF variant (CV). CV-1 contained the single amino acid exchange R28E. Arg(28) is in close proximity to the CNTFR binding site. Using molecular modeling, we hypothesized that Arg(28) might contribute to IL-6R/CNTFR plasticity of CNTF. CV-2 to CV-5 were generated by transferring parts of the CNTFR-binding site from cardiotrophin-like cytokine to CNTF. Cardiotrophin-like cytokine selectively signals via the CNTFR·gp130·LIFR complex, albeit with a much lower affinity compared with CNTF. As shown by immunoprecipitation, all CNTF variants retained the ability to bind to CNTFR. CV-1, CV-2, and CV-5, however, lost the ability to bind to IL-6R. Although all variants induced cytokine-dependent cellular proliferation and STAT3 phosphorylation via CNTFR·gp130·LIFR, only CV-3 induced STAT3 phosphorylation via IL-6R·gp130·LIFR. Quantification of CNTF-dependent proliferation of CNTFR·gp130·LIFR expressing cells indicated that only CV-1 was as biologically active as CNTF. Thus, the CNTFR-selective CV-1 will allow discriminating between CNTFR- and IL-6R-mediated effects in vivo.

• Authors: Eva-Maria Wagener, Matthias Aurich, Samadhi Aparicio-Siegmund, Doreen M Floss, Christoph Garbers, Kati Breusing, Björn Rabe, Ralf Schwanbeck, Joachim Grötzinger, Stefan Rose-John, Jürgen Scheller
• Journal: The Journal of biological chemistry (J Biol Chem) Vol. 289 Issue 26 Pg. 18442-50 (Jun 27 2014) ISSN: 1083-351X [Electronic] United States
• PMID: 24802752 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

Chemical References

• Ciliary Neurotrophic Factor
• Interleukin-6
• LIFR protein, human
• Leukemia Inhibitory Factor Receptor alpha Subunit
• Receptor, Ciliary Neurotrophic Factor
• Receptors, Interleukin-6
• STAT3 Transcription Factor
• Cytokine Receptor gp130

Topics

• Amino Acid Substitution
• Ciliary Neurotrophic Factor (genetics, metabolism)
• Cytokine Receptor gp130 (genetics, metabolism)
• Humans
• Interleukin-6 (metabolism)
• Leukemia Inhibitory Factor Receptor alpha Subunit (genetics, metabolism)
• Mutation, Missense
• Phosphorylation
• Receptor, Ciliary Neurotrophic Factor (genetics, metabolism)
• Receptors, Interleukin-6 (genetics, metabolism)
• STAT3 Transcription Factor (genetics, metabolism)
• Signal Transduction