scFv single chain antibody variable fragment as inverse agonist of the beta2-adrenergic receptor.
Antibodies directed against the second extracellular loop of G protein-coupled receptors were shown to possess functional activities. Using a functional monoclonal antibody against the human beta2-adrenergic receptor, a scFv fragment with high affinity for the target epitope was constructed and produced. The fragment recognized the beta2-adrenergic receptors on A431 cells, blocked cAMP accumulation induced by the beta2-agonist salbutamol, and decreased basal cAMP accumulation in the same cells. Their in vitro activity was tested on neonatal rat cardiomyocytes. The antibody fragments blocked the chronotropic activity induced by the beta2-agonist clenbuterol. They also decreased the in vivo heart beating frequency of mice pretreated with bisoprolol (a beta1-adrenergic receptor antagonist) for 4 min after injection. The immunological approach presented here may serve as a strategy for the synthesis of a new class of allosteric modulators for G protein-coupled receptors.
Peter
Jean-Christophe
JC
CNRS, UPR 9021, Institut de Biologie Moléculaire et Cellulaire, Laboratory of Therapeutical Chemistry and Immunology, F-67084 Strasbourg, France.
Eftekhari
Pierre
P
Billiald
Philippe
P
Wallukat
Gerd
G
Hoebeke
Johan
J
D000420:Albuterol / Q000494:pharmacology; D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000737:chemistry; D001483:Base Sequence; D015153:Blotting, Western; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D002976:Clenbuterol / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D006801:Humans; D007135:Immunoglobulin Variable Region / Q000737:chemistry*; D007150:Immunohistochemistry; D007700:Kinetics; D051379:Mice; D008807:Mice, Inbred BALB C; D008957:Models, Genetic; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009206:Myocardium / Q000166:cytology; D010455:Peptides / Q000737:chemistry; D017434:Protein Structure, Tertiary; D051381:Rats; D018343:Receptors, Adrenergic, beta-2 / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D013997:Time Factors
D000911:Antibodies, Monoclonal; D007135:Immunoglobulin Variable Region; D010455:Peptides; D018343:Receptors, Adrenergic, beta-2; D000242:Cyclic AMP; D000420:Albuterol; D002976:Clenbuterol