Activation of Extracellular-regulated Kinase Pathways in Ovarian Granulosa Cells by the Novel Growth Factor Type 1 Follicle-stimulating Hormone Receptor

Abstract

SUMMARYFollicle stimulating hormone (FSH) regulated growth and function of the ovarian follicle was previously thought to be mediated solely through activation of Gs-coupled receptors. In this study, we show for the first time that this function is predominantly mediated through the alternatively spliced and novel growth factor type 1 receptor (oFSH-R3) that is also present in the

Follicle stimulating hormone‐induced growth promotion and gene expression profiles on ovarian surface epithelial cells

“…Similar to the previous reports, 3,7,14,15 we showed a significant increase in cell proliferation by FSH treatment on human OSE cell lines, all proven to express FSHR, in dose-and time-dependent manner. Several mechanisms were discussed by other investigators for the FSH stimulated cell proliferation, such as mitogen-activated protein kinase (MAPK) cascade 15 and extracellular-regulated kinase (ERK1 and ERK2) cascade.…”

FSH–FSHR3–stem cells in ovary surface epithelium: basis for adult ovarian biology, failure, aging, and cancer

“…Szotek et al (2008) using BrdU incorporation and doxycycline inducible histone 2B-green fluorescent protein pulse-chase techniques identified a label-retaining stem/progenitor population in the coelomic epithelium of the adult mouse ovary. These cells were observed to exhibit quiescence with asymmetric label retention and functional response to estrous cycling in vivo by proliferation, showed in vitro Babu et al (1999) and Toyuz et al (2000) HEK 293 cells were transfected with FSHR isoforms R1, R2 and R3 Only R3 induced rise in intracellular calcium in response to FSH treatment LH or individual alpha or beta subunits of FSH showed no effect Response was because of calcium influx and not due to intracellular mobilization of calcium This was further confirmed since use of calcium channel blocker suppressed the response FSH response via FSHR3 was seen in both ovary and testis Babu et al (2000) Immortalized granulosa cells lacking endogenous FSHR were used for transfection with R1 and R3 FSH associated proliferation was studied by BrdU/ triturated thymidine uptake Transfected cells showed rapid and transient activation of ERK1 and ERK2 pathways Pretreatment with MAPK/ERK and PKC inhibitors prior to FSH stimulation blocked ERK1 and ERK2 activation suggesting that FSH acts via MAPK/ERK pathway to induce proliferation Babu et al (2001) Investigated hormonal regulation of FSHR3 after PMSG treatment in immature mice FSHR3 levels were significantly up-regulated by RTPCR compared to FSHR1 after PMSG FSHR3 were localized in granulosa cells membrane Li et al (2007) Tested the hypothesis whether FSH can stimulate ovarian cancer cell proliferation by acting on FSHR3, using the tumorigenic mouse OSE cell line ID8 FSH enhanced ID8 proliferation in a concentration-dependent fashion Signalling pathway included cAMP-independent activation of ERK downstream of an SNX482 sensitive component likely to be the Cav2.3 calcium channel Northern analysis using probes specific for exons 7 and 11 of FSHR identified consistently only one 1.9 kb transcript Immunoblot analysis confirmed expression of FSHR3 but not FSHR1 in ID8 Data suggest that signalling promotes proliferation of ovarian cancer cells Patel et al (2013) Studied sheep ovary surface epithelium cells in vitro Stem cells of two different sizes (VSELs and OGSCs), few blood cells and epithelial cells were visualized in OSE smears Stem cells expressed FSHR whereas the epithelial cells were negative Upon FSH treatment, stem cells underwent rapid proliferation within 15 h in vitro as visualized by presence of germ cell nests In situ hybridization studies revealed selective activation of FSHR3 after FSH treatment RNA was extracted from the cultured cells after 3 and 15 h and studied for FSHR1 and FSHR3 transcripts. Only FSHR3 mRNA levels were up regulated at 3 h and return to basal level by 15 h Results show that FSH via FSHR3 stimulates the ovarian stem cells to undergo proliferation, clonal expansion and further differentiation Sullivan et al (2013) Studied relative expression of FSHR1, FSHR2 and FSHR3 in sheep ovarian follicles from normal estrus cycle Follicular fluid was aspirated from small (2.0 mm), medium (2.1-4.0 mm), large (4.1-6.0 mm) and pre-ovulatory (more than 6.1 mm) follicles.…”

Differentiation of the bovine dominant follicle from the cohort upregulates mRNA expression for new tissue development genes

“…The splicing factor arginine/serine-rich 9 encoded by SFRS9 regulates constitutive splicing of RNA and modulation of the selection of alternative splice sites (Screaton et al 1995). Interestingly, bovine granulosa cells from large follicles express differentially spliced gonadotrophin receptor mRNA variants (LHCGR: Kawate & Okuda 1998;FSHR: Rajapaksha et al 1996), and such differential expression of splice variants may modify receptor response in growing follicles (Babu et al 2000). In fact, this study has identified a new 3 0 truncated aromatase mRNA splice variant (DQ004742) expressed in bovine granulosa cells.…”