title: Magneto-nanosensor platform for probing low-affinity protein-protein interactions and identification of a low-affinity PD-L1/PD-L2 interaction.
abstract: Substantial efforts have been made to understand the interactions between immune checkpoint receptors and their ligands targeted in immunotherapies against cancer. To carefully characterize the complete network of interactions involved and the binding affinities between their extracellular domains, an improved kinetic assay is needed to overcome limitations with surface plasmon resonance (SPR). Here, we present a magneto-nanosensor platform integrated with a microfluidic chip that allows measurement of dissociation constants in the micromolar-range. High-density conjugation of magnetic nanoparticles with prey proteins allows multivalent receptor interactions with sensor-immobilized bait proteins, more closely mimicking natural-receptor clustering on cells. The platform has advantages over traditional SPR in terms of insensitivity of signal responses to pH and salinity, less consumption of proteins and better sensitivities. Using this platform, we characterized the binding affinities of the PD-1-PD-L1/PD-L2 co-inhibitory receptor system, and discovered an unexpected interaction between the two known PD-1 ligands, PD-L1 and PD-L2.
authors.affiliation: Department of Mechanical Engineering, Stanford University, Stanford, California 94305, USA.
authors.forename: Jung-Rok
authors.initials: JR
authors.lastname: Lee
authors.affiliation: Department of Mechanical Engineering, Stanford University, Stanford, California 94305, USA.
authors.forename: Daniel J B
authors.initials: DJ
authors.lastname: Bechstein
authors.affiliation: Department of Chemical Engineering, Stanford University, Stanford, California 94305, USA.
authors.forename: Chin Chun
authors.initials: CC
authors.lastname: Ooi
authors.affiliation: Department of Proteomics and Biological Resources, Genentech, South San Francisco, California 94080, USA.
authors.forename: Ashka
authors.initials: A
authors.lastname: Patel
authors.affiliation: Department of Bioengineering, Stanford University, Stanford, California 94305, USA.|Division of Plastic and Reconstructive Surgery, Harvard University, Boston, Massachusetts 02114, USA.
authors.forename: Richard S
authors.initials: RS
authors.lastname: Gaster
authors.affiliation: Department of Bioengineering, Stanford University, Stanford, California 94305, USA.
authors.forename: Elaine
authors.initials: E
authors.lastname: Ng
authors.affiliation: Department of Proteomics and Biological Resources, Genentech, South San Francisco, California 94080, USA.
authors.forename: Lino C
authors.initials: LC
authors.lastname: Gonzalez
authors.affiliation: Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, USA.|Department of Electrical Engineering, Stanford University, Stanford, California 94305, USA.
authors.forename: Shan X
authors.initials: SX
authors.lastname: Wang
mesh_terms: D060890:B7-H1 Antigen / Q000378:metabolism*; D003199:Computer Systems; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008280:Magnetics / Q000379:methods*; D053758:Nanoparticles / Q000737:chemistry*; D061027:Programmed Cell Death 1 Ligand 2 Protein / Q000378:metabolism*; D011485:Protein Binding; D025941:Protein Interaction Mapping; D054712:Salinity
chemical_list: D060890:B7-H1 Antigen; C423236:CD274 protein, human; C556977:PDCD1LG2 protein, human; D061027:Programmed Cell Death 1 Ligand 2 Protein