Rational design of selective bispecific EPO-R/CD131 agonists.

This article focuses on the rational design and characterization of bispecific protein agonists that selectively activate the erythropoietin receptor (EPO-R) and CD131 heterodimer complex (EPO-R/CD131), distinct from the homodimeric EPO-R/EPO-R signaling involved in erythropoiesis. Using structural modeling informed by AlphaFold 3 and known antibody fragment structures, the authors engineered tandem single-chain variable fragments (scFvs) and bispecific Fc fusion proteins that bind both EPO-R and CD131, inducing STAT5 phosphorylation and supporting proliferation in cell lines dependent on EPO-R/CD131 signaling. Functional assays demonstrated that these bispecific constructs activate signaling and proliferation in a CD131-dependent manner, with linker length between scFvs influencing activity consistent with the structural model. These findings provide a foundation for developing selective EPO-R/CD131 agonists with potential therapeutic applications in neuroprotection, aiming to avoid the hematopoietic and pro-thrombotic effects associated with conventional EPO therapies.