Characterization of the Biological Activities of Human Luteinizing Hormone and Chorionic Gonadotropin by a Förster Resonance Energy Transfer-Based Biosensor Assay

Abstract

A Förster resonance energy transfer (FRET)-based cyclic adenosine monophosphate (cAMP) biosensor was used to study the activation of the mutual receptor for human luteinizing hormone (hLH) and human chorionic gonadotropin (hCG) in living cells stably expressing the shared recombinant receptor for these hormones. This work demonstrates the applicability of a cAMP biosensor-based assay for the study of receptor-mediated signal transduction and the characterization of the biological activities of gonadotropins and their isoforms. The importance of this approach lies in the fact that only the active portion of the total hormone concentration elicits a measurable response. No significant differences in early receptor activation profiles were detected for either of the tested recombinant gonadotropins. However, the subsequent physiological regulations mediated by these hormones may be more complex. The ability to detect biologically active hormones at low concentrations forms the basis for the future quantification of human chorionic gonadotropin in embryo culture medium and the use of this information for unbiased embryo selection during in vitro fertilization. Herein, a novel method for describing the biological activities of gonadotropins in various samples and preparations is reported.