Intrinsically disordered ligands for the control of receptor uptake by endocytosis

Abstract

Endocytosis plays a crucial role in signaling, recycling, and degradation of receptors. Controlling endocytosis of specific receptors is therefore a major goal for both basic science and medicine. While antibody-induced dimerization can drive signaling-induced uptake of some receptors, the steric bulk of antibodies generally inhibits endocytosis, such that control over receptor uptake remains an unmet need. Recent work has demonstrated that attractive interactions between intrinsically disordered proteins drive inward membrane curvature, a key step in endocytosis. To harness this phenomenon for the control of receptor uptake, we designed chimeras that consisted of disordered domains fused to ligands for specific receptors. These chimeras condensed on membrane surfaces, driving receptor clustering and uptake via clathrin-mediated endocytosis. In contrast, chimeras that repelled one another resisted condensation, helping receptors escape endocytosis and remain on the cell surface. Taken together, these results suggest that by modulating the amino acid sequence of intrinsically disordered ligands, we can promote or hinder the internalization of specific receptors by endocytic pathways. More broadly, these findings suggest a generalizable strategy for controlling the plasma membrane lifetime of diverse receptors, opening up new pathways for modulating cellular behavior and delivering therapeutics. Significance StatementCells regulate signaling by continuously internalizing receptors from their surfaces using endocytosis. Controlling receptor internalization would provide new tools for addressing diverse diseases. While antibodies can cluster specific receptors on the cell surface, their steric bulk and rigidity inhibit endocytosis. In contrast, here we demonstrate that engineered ligands containing intrinsically disordered domains form flexible complexes that precisely control receptor internalization. Disordered ligands that attract one another condense receptors at sites of endocytosis, driving uptake, while repulsive disordered ligands prevent condensation such that receptors remain on the cell surface. By tuning the amino acid sequence of the disordered domain, a ligand can be switched from promoting to inhibiting receptor internalization, offering the opportunity to control cell signaling and therapeutic delivery.