Pleotropism of gonadotropin action

Evidence exists that the gonadotropins LH and FSH can substitute to each other under certain circumstances, in addition to the fact that they can act together in granulosa cells. The aim of this study is to investigate how the two human gonadotropins influence each other in granulosa cells expressing both receptors, or by co-culturing cells expressing either the LHCGR or the FSHR (as a model granulosa/theca interaction). Plasmids encoding the c-myc-tagged-LHCGR and the FLAG-tagged FSHR under the control of an inducible coumermycin-responsive or doxycycline-responsive promoter, respectively were produced. These plasmids were used to permanently transfect human granulosa cell-derived KGN cells and HEK293 cells. The following cell lines were obtained and partially characterized: #1 c-myc-tagged-LHCGR-KGN; #2 FLAG-tagged FSHR_HEK293; #3 FLAG-tagged FSHR-KGN; #4 Double, c-myc-tagged-LHCGR and FLAG-tagged FSHR-KGN. After induction of receptor expression, the cell lines #1 and #2 and #3 responded to hCG and FSH stimulation, respectively by producing cAMP. Receptor expression was demonstrated by RT-PCR and flow cytometry. The characterization of the cell line #4 is ongoing. These cell lines are now available for the study of cell signaling and steroid synthesis, as well as in silico modeling, to gain insight into the dynamics of the intertwined cell response to FSH and LH in granulosa cells. These experiments will continue in parallel in both laboratories involved. Our cell lines represent new, very valuable instruments for the study of molecular pharmacology of FSH and LH, in order to improve infertility treatment, (multi)follicular growth for assisted reproduction, ovulation and spermatogenesis.