513. LOSS OF BETAGLYCAN DISRUPTS SOMATIC CELL DIFFERENTIATION IN THE FETAL MOUSE OVARY

Abstract

Betaglycan (TGFBR3) is an accessory receptor that modulates the activities of members of the TGF-beta superfamily of growth factors which regulate many aspects of reproductive biology. We reported the presence of betaglycan on somatic and germ cells in fetal murine ovary from 12.5 dpc [1]. However, the role of this receptor in early ovarian development is poorly understood. We hypothesised that, given its expression pattern, betaglycan could serve as a TGFb accessory receptor on both oogonia and somatic cells during early ovarian development. In the current study, we examined the Tgfbr3 (betaglycan) null and wildtype ovary from 11.5–14.5 dpc. During this window of development, no overt morphological phenotype was detected, and cell proliferation (PCNA immunostaining) and apoptosis (active caspase 3 immunostaining) were unchanged in the null ovary. To determine whether somatic and/or germ cell markers were altered in the absence of betaglycan, quantitative real time PCR analysis was conducted using total RNA derived from 11.5–14.5 dpc betaglycan wildtype, heterozygous, and null ovaries (n=3 at each age/genotype). From 12.5 dpc, genes associated with the differentiation of the female somatic lineages Wnt4, Fst, Bmp2 were significantly decreased in the null ovary by 30%–50% (P<0.05) while germ cell markers (Oct4, Mvh) showed no significant changes compared to wildtype ovary. Genes associated with the testis-differentiation pathway (e.g. Sox9, Cyp11a1, Cyp17a1, Hsd3b, Insl3, Dhh) were not aberrantly expressed in betaglycan null or heterozygous ovary, with expression levels very low to undetectable. Collectively, these data suggest that while betaglycan does not appear to play a key role in establishing the structure of the ovary, loss of this receptor results in a disruption to the differentiation of ovarian somatic cells.