1. Evidence for an involvement of the ubiquitin-like modifier ISG15 in MHC class I antigen presentation.
- Author
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Held T, Basler M, Knobeloch KP, and Groettrup M
- Subjects
- Animals, Cytokines deficiency, Cytokines genetics, Cytokines metabolism, HEK293 Cells, Histocompatibility Antigens Class I metabolism, Humans, Lymphocytic choriomeningitis virus genetics, Lymphocytic choriomeningitis virus immunology, Mice, Mice, Inbred BALB C, Mice, Inbred C57BL, Mice, Knockout, Nucleocapsid Proteins genetics, Nucleocapsid Proteins immunology, Nucleocapsid Proteins metabolism, Proteasome Endopeptidase Complex immunology, Proteasome Endopeptidase Complex metabolism, Protein Modification, Translational immunology, Proteolysis, Recombinant Fusion Proteins genetics, Recombinant Fusion Proteins immunology, Recombinant Fusion Proteins metabolism, Ubiquitin Thiolesterase deficiency, Ubiquitin Thiolesterase genetics, Ubiquitin Thiolesterase immunology, Ubiquitins deficiency, Ubiquitins genetics, Ubiquitins metabolism, Antigen Presentation immunology, Cytokines immunology, Histocompatibility Antigens Class I immunology, Ubiquitins immunology
- Abstract
The IFN stimulated gene 15 (ISG15) encodes a 15-kDa ubiquitin-like protein, that is induced by type I IFNs and is conjugated to the bulk of newly synthesized polypeptides at the ribosome. ISG15 functions as an antiviral molecule possibly by being covalently conjugated to viral proteins and disturbing virus particle assembly. Here, we have investigated the effect of ISGylation on degradation and antigen presentation of viral and cellular proteins. ISGylation did not induce proteasomal degradation of bulk ISG15 target proteins neither after overexpressing ISG15 nor after induction by IFN-β. The MHC class I cell surface expression of splenocytes derived from ISG15-deficient mice or mice lacking the catalytic activity of the major de-ISGylating enzyme USP18 was unaltered as compared to WT mice. Fusion of ubiquitin or FAT10 to the long-lived nucleoprotein (NP) of lymphocytic choriomeningitis virus accelerated the proteasomal degradation of NP while fusion to ISG15 did not detectably speed up NP degradation. Nevertheless, MHC-I restricted presentation of two epitopes of NP were markedly enhanced when it was fused to ISG15 similarly to fusion with ubiquitin or FAT10. Thus, we provide evidence that ISG15 can enhance the presentation of antigens on MHC-I most likely by promoting co-translational antigen processing., (© 2020 Wiley-VCH GmbH.)
- Published
- 2021
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