Mimicking extracellular matrix-mediated mechano-activation by antibodies to control signaling of the adhesion G protein-coupled receptor GPR126/ADGRG6

The adhesion G protein-coupled receptor (aGPCR) GPR126/ADGRG6 plays an important role in several physiological functions, such as myelination, peripheral nerve repair and osteoblast differentiation, which renders the receptor an attractive pharmacological target. GPR126 is a mechano-sensor that incorporates signals from the extracellular matrix (ECM) through binding to its N-terminal ligands collagen IV and laminin 211. Since ECM components are not suitable therapeutics alternate compounds with more favorable characteristics would be desirable that can mimic the physiologic activation pattern. Antibodies could present an apt alternative as they can specifically target the N-terminus of the receptor, reach multiple tissue compartments and have been shown to modulate GPCR activity levels.In this study, we use a monoclonal antibody targeting an N-terminal HA-epitope to induce receptor signaling, which can be enhanced through the addition of secondary antibodies. Using single cell atomic force microscopy (AFM) in combination with a fluorescent cAMP sensor, we show that antibody-mediated activation is achieved through combined pushing and pulling forces, while collagen IV and laminin 211 only mediate GPR126 activation through pushing or pulling, respectively. Thus, the antibody-mediated approach can reliably mimic the activation induced by both endogenous ligands. Our findings show that antibody-mediated activation for GPR126 is feasible and can be used for precise targeting of this receptor, thereby establishing it as a pharmaceutical target.