Abstract
The aim of the present study was to investigate the hormonal regulation of hyaluronan (HA) components in sheep granulosa cells. HA components are present in the reproductive tract and have a range of physical and signalling properties related to reproductive function in several species. First, abattoir-derived ovaries of sheep were used to determine the localisation of HA synthase (HAS) 1-3 and CD44 proteins in antral follicles. Staining for HAS1-3 and CD44 proteins was most intense in the granulosa layer. Accordingly, the expression of HAS2, HAS3 and CD44 mRNA was measured in cultured granulosa cells exposed to 0-50ngmL(-1) of 17β-oestradiol and different combinations of oestradiol, gonadotropins, insulin-like growth factor (IGF)-1 and insulin for 48-96h (1ngmL(-1) FSH, 10ngmL(-1) insulin, 10ngmL(-1) IGF-1, 40ngmL(-1) E2 and 25ngmL(-1) LH.). mRNA expression was quantified by real-time polymerase chain reaction using a fold induction method. The results revealed that the hormones tested generally stimulated mRNA expression of the genes of interest in cultured granulosa cells. Specifically, oestradiol, when combined with IGF-1, insulin and FSH, stimulated HAS2 mRNA expression. Oestradiol and LH had synergistic effects in increasing HAS3 mRNA expression. In conclusion, we suggest that the hormones studied differentially regulate HAS2, HAS3 and CD44 in ovine granulosa cells in vitro. Further work is needed to address the signalling pathways involved.
Highlights
Folliculogenesis proceeds under the coordinated control of systemic gonadotropin hormones and locally produced growth factors
Immunohistochemistry of the HA system in sheep ovarian follicles As shown in Fig. 1a, HAS1, HAS2, HAS3 and CD44 proteins were present in the antral follicles
The H-Score results are approximately double for HAS2 and HAS3 and nearly fourfold higher for CD44 presence in the granulosa cells (GCs) layer compared with the theca cell layer
Summary
Folliculogenesis proceeds under the coordinated control of systemic gonadotropin hormones and locally produced growth factors. Insulin-like growth factor (IGF)-1 mediates the transition from gonadotropin responsiveness to dependency via enhancement of gonadotropin receptor expression and stimulation of steroidogenesis (Silva et al 2009; Scaramuzzi et al 2011). The multiple layers of granulosa cells (GCs) in growing follicles are surrounded by a basal lamina that separates them from the theca. This specialised extracellular matrix (ECM) manages fluid dynamics and provides mechanical support. HA actively participates in both intra- and extracellular pathways, influencing cellular behaviour such as migration, growth, motility, adhesion and differentiation (Toole 2001; Toole et al 2002; Bodevin-Authelet et al 2005; Itano 2008)
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