Regulation of fibrillins and modulators of TGFβ in fetal bovine and human ovaries

Abstract

Fibrillins 1-3 are stromal extracellular matrix proteins that play important roles in regulating TGFβ activity, which stimulates fibroblasts to proliferate and synthesize collagen. In the developing ovary, the action of stroma is initially necessary for the formation of ovigerous cords and subsequently for the formation of follicles and the surface epithelium of the ovary. FBN3 is highly expressed only in early ovarian development and then it declines. In contrast, FBN1 and 2 are upregulated in later ovarian development. We examined the expression of FBN1-3 in bovine and human fetal ovaries. We used cell dispersion and monolayer culture, cell passaging and tissue culture. Cells were treated with growth factors, hormones or inhibitors to assess the regulation of expression of FBN1-3. When bovine fetal ovarian tissue was cultured, FBN3 expression declined significantly. Treatment with TGFβ-1 increased FBN1 and FBN2 expression in bovine fibroblasts, but did not affect FBN3 expression. Additionally, in cultures of human fetal ovarian fibroblasts (9-17 weeks gestational age), the expression of FBN1 and FBN2 increased with passage, whereas FBN3 dramatically decreased. Treatment with activin A and a TGFβ family signaling inhibitor, SB431542, differentially regulated the expression of a range of modulators of TGFβ signaling and of other growth factors in cultured human fetal ovarian fibroblasts suggesting that TGFβ signaling is differentially involved in the regulation of ovarian fibroblasts. Additionally, since the changes in FBN1-3 expression that occur in vitro are those that occur with increasing gestational age in vivo, we suggest that the fetal ovarian fibroblasts mature in vitro.

Could perturbed fetal development of the ovary contribute to the development of polycystic ovary syndrome in later life?

“…For screening of possible regulators of PCOS candidate genes in the fetal ovary, RNA extracted from cultured and treated bovine fetal fibroblasts from another study was used [59]. All ovaries analysed in the current study were from the second trimester.…”

Morphometric and gene expression analyses of stromal expansion during development of the bovine fetal ovary

“…Ovarian stroma contains fibroblasts and extracellular matrix. The matrix contains reticular fibres (Bandeira et al 2015), fibrillar collagens (Iwahashi et al 2000;Hummitzsch et al 2013Hummitzsch et al , 2015, decorin (Hummitzsch et al 2013(Hummitzsch et al , 2015, fibronectin (Hummitzsch et al 2013), versican (McArthur et al 2000Hummitzsch et al 2013Hummitzsch et al , 2015, fribillins (Prodoehl et al 2009;Hatzirodos et al 2011;Hummitzsch et al 2013Hummitzsch et al , 2015Bastian et al 2016), latent transforming growth factor b (TGFb)-binding proteins (Prodoehl et al 2009;Hatzirodos et al 2011;Bastian et al 2016) and hyaluronan (Kobayashi et al 1999;Irving-Rodgers and Rodgers 2007). Stromal extracellular matrix components have been linked to the growth and maturation of follicles in sheep (Huet et al 2001) by maintaining the shape of granulosa cells as well as their survival and proliferation in vitro.…”

“…Many changes in gene expression occur during fetal ovarian development, such as expression of the pluripotency marker POU class 5 homeobox 1 (POU5F1 or Oct4), deleted in azoospermia-like (DAZL), forkhead box L2 (FOXL2), as well as members of the TGF family including TGFB1, 2 and 3, activins, inhibins and bone morphogenetic proteins (BMPs; reviewed in Sarraj and Drummond 2012). The ovarian stroma is potentially influenced by several factors, including members of the TGFb pathway (Roy and Kole 1998;Bastian et al 2016) and androgens and oestrogens (Abbott et al 2006;Loverro et al 2010). Abnormal development of ovarian stroma could potentially lead to an altered stromal volume in adulthood, as observed in polycystic ovary syndrome (PCOS;Hughesdon 1982;Fulghesu et al 2001;Abbott et al 2006;Li and Huang 2008).…”

Transcript abundance of stromal and thecal cell related genes during bovine ovarian development

“…Fibrillin 3 is expressed in the first trimester only, and then in trimester 2 fibrillins 1 and 2 are expressed [6]. This maturational change in fibrillin types also occurs when fetal fibroblasts are cultured in vitro [7] and since fibrillins bind LTBPs and regulate bioavailability of TGFβ in tissues, presumably the action of TGFβ changes during fetal development of the ovary.…”