A deamidated interferon-ß variant binds to integrin αvß3.

Human type I interferons are a family of pleiotropic cytokines with antiviral, anti-proliferative and immunomodulatory activities. They signal through the same cell surface receptors IFNAR1 and IFNAR2 yet evoking markedly different physiological effects. One differentiating factor of interferon-beta (IFN-ß) from other type I interferons is the presence of theAsn-Gly-Arg (NGR) sequence motif, which, upon deamidation, converts to Asp-Gly-Arg (DGR) and iso-Asp-Gly-Arg (iso-DGR) motifs. In other proteins, the NGR and iso-DGR motifs are reported as CD13- and αvß3, αvß5, αvß6, αvß8 and α5ß1 integrin-binding motifs, respectively. The scope of this study was to perform exploratory surface plasmon resonance (SPR) experiments to assess the binding properties of a deamidated IFN-ß variant to integrins. For this purpose, integrin αvß3 was selected as a reference model within the iso-DGR- integrin binding members. The obtained results show that deamidated IFN-ß binds integrin αvß3 with nanomolar affinity and that the response was dependent on the deamidation extent. Based on these results, it can be expected that deamidated IFN-ß also binds to other integrin family members that are able to bind to the iso-DGR binding motif. The novel binding properties could help elucidate specific IFN-ß attributes that under physiological conditions may be modulated by the deamidation.

Biological Functions of Interferon ß-1a Are Enhanced By Deamidation.

Human type I Interferons (IFN-ß, IFN-ɛ, IFN-κ, IFN-ω, and 12 subtypes of IFN-α) are a family of pleiotropic cytokines with antiviral, antiproliferative, and immunomodulatory activities. They signal through the same cell surface receptors, IFNAR1 and IFNAR2, yet evoking markedly differential potency. One differentiating factor of IFN-ß from other type I interferons is the presence of a consensus sequence (NG) for deamidation. Comparing almost completely deamidated IFN-ß-1a with untreated IFN-ß-1a, this present study reports the increased activities in 3 in-vitro bioassays testing the antiviral, antiproliferative, and immunomodulatory properties, respectively, of the molecule. Deamidated IFN-ß-1a has the potential to improve current therapies in multiple sclerosis, and its ability to potentiate the MHC-Class I expression suggests a clinical benefit in diseases where the downmodulation of the MHC-class I expression plays a role (eg, in immuno-oncology combination therapies or antiviral agents). The present study on IFN-ß deamidation adds a new prospective on deamidation as part of a posttranslational modification code that allows the modulation of the biological properties of proteins. Moreover, it underlines the unique IFN-ß-1a properties that differentiate this molecule from other members of the type I interferon family.