Rational design of interleukin-21 antagonist through selective elimination of the gammaC binding epitope

Lishan Kang, Kent Bondensgaard, Tengkun Li, Rune Hartmann, Siv A Hjorth

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    14 Citations (Scopus)

    Abstract

    The cytokine interleukin (IL)-21 exerts pleiotropic effects acting through innate as well as adaptive immune responses. The activities of IL-21 are mediated through binding to its cognate receptor complex composed of the IL-21 receptor private chain (IL-21Ralpha) and the common gamma-chain (gammaC), the latter being shared by IL-2, IL-4, IL-7, IL-9, and IL-15. The binding energy of the IL-21 ternary complex is predominantly provided by the high affinity interaction between IL-21 and IL-21Ralpha, whereas the interaction between IL-21 and gammaC, albeit essential for signaling, is rather weak. The design of IL-21 analogues, which have lost most or all affinity toward the signaling gammaC chain, while simultaneously maintaining a tight interaction with the private chain, would in theory represent candidates for IL-21 antagonists. We predicted the IL-21 residues, which compose the gammaC binding epitope using homology modeling and alignment with the related cytokines, IL-2 and IL-4. Next we systematically analyzed the predicted binding epitope by a mutagenesis study. Indeed two mutants, which have significantly impaired gammaC affinity with undiminished IL-21Ralpha affinity, were successfully identified. Functional studies confirmed that these two novel hIL-21 double mutants do act as hIL-21 antagonists.
    Original languageEnglish
    JournalJournal of Biological Chemistry
    Volume285
    Issue16
    Pages (from-to)12223-31
    Number of pages9
    ISSN0021-9258
    DOIs
    Publication statusPublished - 16 Apr 2010

    Keywords

    • Amino Acid Sequence
    • Amino Acid Substitution
    • Binding Sites
    • Cell Line
    • Drug Design
    • Epitopes
    • Humans
    • Interleukin-2
    • Interleukin-4
    • Interleukins
    • Models, Molecular
    • Molecular Sequence Data
    • Multiprotein Complexes
    • Mutagenesis, Site-Directed
    • Protein Interaction Domains and Motifs
    • Receptors, Interleukin-21
    • Recombinant Proteins
    • Sequence Homology, Amino Acid
    • Structural Homology, Protein

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