Reversible immunoneutralization of human follitropin receptor.
Investigations of the human Follitropin receptor (hFSHR) have failed to identify the tertiary structure that forms the active hormone-receptor interaction site which is essential to develop an immunocontraceptive based upon the receptor. To identify such a domain of hFSHR, an immunoneutralizing monoclonal antibody (mAb) 106-105 (IgG2b) was generated. Flow cytometry tested whether mAb 106-105 recognized native hFSHR. The epitope of mAb 106-105 was mapped by Western blot and by peptide ELISA. Inhibition of hFSH binding and bioactivity was determined by radioreceptor assay and by cAMP production, respectively. MAb 106-105 bound native hFSHR through an epitope including residues 300-315. MAb 106-105 completely blocked hormone binding to receptor and cAMP production by Y1-R cells expressing hFSHR. These effects were completely reversible by increasing the concentration of hFSH. Coincubation of this antibody with peptide D300-F315 blocked antibody activity. These data demonstrate that a discrete linear hFSHR epitope is a target for interference with hormone activity. These results further demonstrate that antibody binding to the extracellular domain (ECD) of hFSHR and subsequent bioactivation can be modulated through a domain specific hindrance, offering a reversible immunoneutralizing target.
Lindau-Shepard
B
B
Division of Molecular Medicine, David Axelrod Institute for Public Health, Wadsworth Center, New York State Department of Health, 120 New Scotland Avenue, Albany, NY 12208, USA.
Brumberg
H A
HA
Peterson
A J
AJ
Dias
J A
JA
D000818:Animals; D000911:Antibodies, Monoclonal / Q000096:biosynthesis / Q000276:immunology; D016466:CHO Cells; D006224:Cricetinae; D000242:Cyclic AMP / Q000378:metabolism; D006801:Humans; D007457:Iodine Radioisotopes; D007553:Isotope Labeling; D051379:Mice; D009500:Neutralization Tests; D010455:Peptides / Q000276:immunology; D011962:Receptors, FSH / Q000276:immunology*; D014407:Tumor Cells, Cultured
D000911:Antibodies, Monoclonal; D007457:Iodine Radioisotopes; D010455:Peptides; D011962:Receptors, FSH; D000242:Cyclic AMP