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Keywords:

  • interferon;
  • IFN-ζlimitin;
  • cytokine;
  • structure;
  • signal;
  • Daxx;
  • Crk

Abstract

Interferon (IFN)-ζlimitin has been considered as a novel type I IFN by the Nomenclature Committee of the International Society for Interferon and Cytokine Research. IFN-ζlimitin shows some sequence homology with IFN-α and IFN-β, has a globular structure with five α-helices and four loops, and recognizes IFN-α/β receptor. Although IFN-ζlimitin displays antiviral, immunomodulatory, and antitumor effects, it has much less lymphomyelosuppressive activities than IFN-α. Treatment of cells with type I IFNs induces and/or activates a number of molecules, which regulate cell cycle and apoptosis. It is noteworthy that IFN-ζlimitin activates the Tyk2-Daxx and Tyk2-Crk pathways weaker than IFN-α. Because experiments using antisense oligonucleotides have revealed their essential role in type I IFN-related suppression of lympho-hematopoiesis, little ability of IFN-ζlimitin to activate the Tyk2-dependent signaling pathway may explain its uniquely narrow range of biological activities. Further analysis of structure-function relationship of type I IFNs will establish an engineered cytokine with useful features of IFN-ζlimitin.