Tuning of granulopoietic signaling by de novo designed agonists

Enhancing cytokine-based therapies by systematically tuning how an agonist associates its receptor is emerging as a powerful new concept in drug discovery. Here, we report the design and characterization of agonists that tune the granulocyte-colony stimulating factor receptor (G-CSFR) activity, which is central for the proliferation and granulocytic differentiation of hematopoietic stem cells. Using design agonists, we study the impact of varying the receptor-binding affinity and dimerization geometry on receptor association, downstream signaling, and cellular response. Hence, we achieved agonists with altered signaling specificities that are hyper-thermostable, can outcompete the native ligand (G-CSF), and bias granulopoietic differentiation over triggering proliferation. Furthermore, the design agonists differentially modulate the kinetics and amplitudes of signal transduction pathways, and gene expression patterns. Unlike G-CSF, they achieve selective activation of gene sets with hematopoietic functions with minimal unwanted effects on immunomodulatory signaling. These findings demonstrate the potential of dissecting the complex G-CSFR signaling, and open up ways for new therapeutic applications for designed cytokines. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=116 SRC="FIGDIR/small/568662v3_ufig1.gif" ALT="Figure 1"> View larger version (30K): org.highwire.dtl.DTLVardef@af56e3org.highwire.dtl.DTLVardef@171920forg.highwire.dtl.DTLVardef@12c2c0aorg.highwire.dtl.DTLVardef@ff7556_HPS_FORMAT_FIGEXP M_FIG C_FIG