Hormone-regulated expression and localization of versican in the rodent ovary

Abstract

During ovulation, production of a specialized hyaluronan (HA)-rich matrix cross-linked by associated HA binding factors causes expansion of the cumulus oocyte complex. Versican is a member of the hyalectan family that binds HA, provides structure and elasticity to tissues, and impacts cell motility and adhesion. In these studies, we sought to determine whether versican is synthesized by ovulating follicles and localizes along with HA in the expanded cumulus oocyte complex matrix in rodent ovaries and whether its expression and/or localization is altered in anovulatory mutant mice. Analysis of mRNA and protein identified isoforms V0, V1, and V3 versican in mouse and rat ovaries throughout follicular development. In situ hybridization localized versican mRNA most specifically to the granulosa cells. Expression was not significantly altered by estradiol or FSH treatment but was increased up to 10-fold during the periovulatory period after human chorionic gonadotropin treatment. In cultured granulosa cells, forskolin and phorbol 12 myristate 13-acetate or FSH + testosterone increased expression of versican. Immunohistochemical analyses verified versican protein in ovulating follicles localized to the expanded cumulus matrix as well as adjacent to the basement membrane. After ovulation, versican was localized around newly formed corpora lutea and vasculature. Unexpectedly, immunohistochemical analyses also demonstrated versican protein on granulosa cells in early primary and small antral follicles. Versican expression and localization were not altered in progesterone receptor or cyclooxygenase-2 null mice, suggesting that transcription of the versican gene is not a target of these two ovulatory mediators. These observations suggest that versican (V0, V1, and V3) is a matrix component of the granulosa layer throughout folliculogenesis and is enriched in remodeling matrices during ovulation and neovascularization of the corpora lutea.