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Structure of the higher-order IL-25-IL-17RB complex
Structural highlights
FunctionIL25_HUMAN Cytokine produced by various cells such as eosinophils, T-helper type 2 (Th2) cells or epithelial cells that plays a role in internal safety of adaptive immune responses by regulating cytokine production (PubMed:15860795, PubMed:25821217). Promotes and augments T-helper type 2 responses locally or systemically (PubMed:25821217). Exerts its activity via its receptor composed of IL17RA and IL17RB for signal transduction (By similarity). In turn, stimulates the JAK2-STAT5A pathway and promotes the secretion of type-2 associated cytokines including IL4, IL9 and IL13 (PubMed:25821217). Induces also the release of IL8, and IL6 from eosinophils through the combined activation of MAPK and NF-kappa-B pathways (PubMed:15860795). Inhibits the differentiation of T-helper (Th17) cells via the production of IL4, IL5 and IL13 (PubMed:11754819).[UniProtKB:Q8VHH8][1] [2] [3] Publication Abstract from PubMedThe IL-17 family of cytokines and receptors have central roles in host defence against infection and development of inflammatory diseases(1). The compositions and structures of functional IL-17 family ligand-receptor signalling assemblies remain unclear. IL-17E (also known as IL-25) is a key regulator of type 2 immune responses and driver of inflammatory diseases, such as allergic asthma, and requires both IL-17 receptor A (IL-17RA) and IL-17RB to elicit functional responses(2). Here we studied IL-25-IL-17RB binary and IL-25-IL-17RB-IL-17RA ternary complexes using a combination of cryo-electron microscopy, single-molecule imaging and cell-based signalling approaches. The IL-25-IL-17RB-IL-17RA ternary signalling assembly is a C2-symmetric complex in which the IL-25-IL-17RB homodimer is flanked by two 'wing-like' IL-17RA co-receptors through a 'tip-to-tip' geometry that is the key receptor-receptor interaction required for initiation of signal transduction. IL-25 interacts solely with IL-17RB to allosterically promote the formation of the IL-17RB-IL-17RA tip-to-tip interface. The resulting large separation between the receptors at the membrane-proximal level may reflect proximity constraints imposed by the intracellular domains for signalling. Cryo-electron microscopy structures of IL-17A-IL-17RA and IL-17A-IL-17RA-IL-17RC complexes reveal that this tip-to-tip architecture is a key organizing principle of the IL-17 receptor family. Furthermore, these studies reveal dual actions for IL-17RA sharing among IL-17 cytokine complexes, by either directly engaging IL-17 cytokines or alternatively functioning as a co-receptor. , PMID:35863378[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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