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  • Structure of the IL-27 quaternary receptor signaling complex. eLife Caveney, N. A., Glassman, C. R., Jude, K. M., Tsutsumi, N., Garcia, K. C. 2022; 11

    Abstract

    Interleukin 27 (IL-27) is a heterodimeric cytokine that functions to constrain T cell-mediated inflammation and plays an important role in immune homeostasis. Binding of IL-27 to cell surface receptors IL-27Ralpha and gp130 results in activation of receptor-associated Janus Kinases and nuclear translocation of Signal Transducer and Activator of Transcription 1 (STAT1) and STAT3 transcription factors. Despite the emerging therapeutic importance of this cytokine axis in cancer and autoimmunity, a molecular blueprint of the IL-27 receptor signaling complex, and its relation to other gp130/IL-12 family cytokines, is currently unclear. We used cryogenic-electron microscopy to determine the quaternary structure of IL-27, composed of p28 and Ebi3 subunits, bound to receptors, IL-27Ralpha and gp130. The resulting 3.47 A resolution structure revealed a three-site assembly mechanism nucleated by the central p28 subunit of the cytokine. The overall topology and molecular details of this binding are reminiscent of IL-6 but distinct from related heterodimeric cytokines IL-12 and IL-23. These results indicate distinct receptor assembly mechanisms used by heterodimeric cytokines with important consequences for targeted agonism and antagonism of IL-27 signaling.

    View details for DOI 10.7554/eLife.78463

    View details for PubMedID 35579417