Endocrine Abstracts

G protein-coupled receptors are the largest family of mammalian receptors, with key roles in controlling most physiological processes. Ovarian function is no exception, with a key ovarian GPCR, follicle stimulation hormone receptor (FSHR), and its endogenous ligand, FSH, critical for pre-antral-antral follicle growth and survival. An increasingly important way that GPCRs have been shown to regulate ligand specificity and signal amplitude is via association and formation of dimers/oligomers. Although FSHR has been demonstrated to self-associate and homomerize, the physiological regulation and significance of this remains unknown. This study therefore aimed to determine the modulation and functional consequences of FSHR oligomerisation in native ovarian granulosa cells. To do this, an N-terminally FLAG-tagged knock in FSHR mouse was generated. Phenotypic characterisation revealed that ovarian and uterine weights were the same between wild type (WT), FSHRFLAG-/+ and FSHRFLAG+/+suggesting FSH-mediated oestrogen production was maintained. Gross morphological analysis of the reproductive tract and ovaries revealed no differences between these three genotypes. Histological analysis of ovaries showed the presence of follicles at all stages of follicular development in WT, FSHRFLAG-/+ and FSHRFLAG+/+ mice. Additionally, corpora lutea were present in all models supporting intact ovulation. Breeding strategies confirmed fertility of FSHRFLAG-/+ and FSHRFLAG+/+. Isolated of granulosa cells and super resolution analysis of FSHR monomers, dimers and oligomer populations showed ~40% of FSHR were basally associated, comparable to previously published work in HEK293 cells expressing FSHR. Additionally, analysis of the types of FSHR oligomers suggested a predominance of lower order oligomeric complexes. These data support the utilisation of this mouse model for monitoring endogenous, native FSHR oligomerisation, and provide an exciting tool to unravel the physiological roles of these receptor complexes in ovarian function and ageing.