title: In vivo imaging of ligand receptor binding with Gaussia luciferase complementation.
abstract: Studies of ligand-receptor binding and the development of receptor antagonists would benefit greatly from imaging techniques that translate directly from cell-based assays to living animals. We used Gaussia luciferase protein fragment complementation to quantify the binding of chemokine (C-X-C motif) ligand 12 (CXCL12) to chemokine (C-X-C motif) receptor 4 (CXCR4) and CXCR7. Studies established that small-molecule inhibitors of CXCR4 or CXCR7 specifically blocked CXCL12 binding in cell-based assays and revealed differences in kinetics of inhibiting chemokine binding to each receptor. Bioluminescence imaging showed CXCL12-CXCR7 binding in primary and metastatic tumors in a mouse model of breast cancer. We used this imaging technique to quantify drug-mediated inhibition of CXCL12-CXCR4 binding in living mice. We expect this imaging technology to advance research in areas such as ligand-receptor interactions and the development of new therapeutic agents in cell-based assays and small animals.
authors.affiliation: Center for Molecular Imaging, Department of Radiology, University of Michigan Medical School, Ann Arbor, Michigan, USA.
authors.forename: Kathryn E
authors.initials: KE
authors.lastname: Luker
authors.forename: Laura Anne
authors.initials: LA
authors.lastname: Mihalko
authors.forename: Bradley T
authors.initials: BT
authors.lastname: Schmidt
authors.forename: Sarah A
authors.initials: SA
authors.lastname: Lewin
authors.forename: Paramita
authors.initials: P
authors.lastname: Ray
authors.forename: Dmitry
authors.initials: D
authors.lastname: Shcherbo
authors.forename: Dmitriy M
authors.initials: DM
authors.lastname: Chudakov
authors.forename: Gary D
authors.initials: GD
authors.lastname: Luker
mesh_terms: D000818:Animals; D001596:Benzylamines; D001943:Breast Neoplasms / Q000378:metabolism; D045744:Cell Line, Tumor; D054377:Chemokine CXCL12 / Q000032:analysis* / Q000037:antagonists & inhibitors / Q000378:metabolism; D000080027:Cyclams; D005260:Female; D057809:HEK293 Cells; D006571:Heterocyclic Compounds / Q000494:pharmacology; D006801:Humans; D008024:Ligands; D008156:Luciferases / Q000032:analysis / Q000378:metabolism*; D008163:Luminescent Measurements / Q000379:methods*; D051379:Mice; D057054:Molecular Imaging / Q000379:methods*; D009374:Neoplasms, Experimental / Q000378:metabolism; D011485:Protein Binding / Q000187:drug effects; D054387:Receptors, CXCR / Q000032:analysis* / Q000037:antagonists & inhibitors / Q000378:metabolism; D019718:Receptors, CXCR4 / Q000032:analysis* / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: D001596:Benzylamines; D054377:Chemokine CXCL12; D000080027:Cyclams; D006571:Heterocyclic Compounds; D008024:Ligands; D054387:Receptors, CXCR; D019718:Receptors, CXCR4; D008156:Luciferases; C088327:plerixafor