Poster: Cytokine receptors IFNγR1, IL10Rα and IFNαR1/2 cis-dimers significantly enhance the binding of relevant cytokines

Cytokines initiate signaling on target cells by engaging the ectodomains (ECDs) of cell surface receptors. Cytokine receptor dimeric forms are critical for cytokine ligand binding. To mimic the dimeric receptor conformation, we engineered novel cishomodimers for human Type II interferon IFNγ receptor 1 (IFNγR1) and interleukin 10 receptor alpha (IL10Rα), and the cis-heterodimer for human Type I interferon IFNα receptor 1/2 (IFNαR1/2). To generate the IFNγR1 or IL10Rα homodimer, its ECD was fused with a homodimer motif at the C-terminus; to create IFNαR1/2 heterodimer, IFNαR1 and IFNαR2 ECDs were fused with a heterodimer motif at the C-terminus of each chain. These soluble dimeric receptor proteins were expressed/purified from HEK293T cells and could potently bind to the specific antibodies as measured by ELISA. We further investigated the dimeric or monomeric receptor protein binding to the cytokine ligands. Notably, the dimeric forms of IFNγR1, IL10Rα or IFNαR1/2 dramatically enhanced the binding to the relevant cytokine IFNγ, IL-10 or IFNα with >10-fold increases of binding potency based on determined EC50 values, compared to the monomeric receptor proteins. The findings imply that these engineered novel cis-homodimer and cisheterodimer cytokine receptor proteins mimic the native conformation with better bioactivities. These innovative soluble cis-dimer cytokine receptor proteins can be very useful new molecules for basic immunology research and drug discovery.