PARENT SESSION

(T626) EXPRESSION OF HYALURONIDASES IN THE MOUSE OVARY: POSSIBLE INVOLVEMENT IN FOLLICULAR ATRESIA.

Orimoto, Adriana¹, Dumaresq-Doiron, Karine¹, Triggs-Raine, Barbara², Carmona, Euridice^{1, 3}, ¹ Hopital Maisonneuve-Rosemont, Montreal, QC, Canada² U. Manitoba, Winnipeg, MB, Canada³ U. Montreal, Montreal, QC, Canada

ABSTRACT- Mammalian hyaluronidases are all endo-N-acetylhexosaminidases which hydrolyze hyaluronic acid (HA), and to a lesser extent chondroitin sulfate and dermatan sulfate. They comprise a family of six hyaluronidase-like genes with approximately 40% sequence identity to each other. In ovaries, the expression of three hyaluronidases, i.e. Hyal-1, 2 and 3, have been reported, nonetheless, to date, no studies have investigated the role of these enzymes in ovarian function and follicle maturation. In the present work we describe the cellular localization and expression pattern of these three enzymes in the mouse ovary. Our in situ hybridization results showed positive staining for these enzymes specifically in granulosa cells of different follicle stages. To investigate the possible role of these enzymes in follicle maturation, two approaches were used. Firstly, immature mice (3 week-old) were injected with eCG, in order to induce follicle development, and the expression of each hyaluronidase was evaluated by real time RT-PCR in granulosa cells isolated at different time intervals after treatment (0 to 96 h). Secondly, ovarian follicle maturation was analysed in HYAL-1 or -3 deficient mice at different ages in comparison to wild type mice. Our results showed an increase in Hyal-1 and 3 expression at 72-96h after eCG treatment, a period coincident with the induction of atresia in this experimental model. However, no difference was observed in the number of follicles at different stages in ovary sections of HYAL-1 or -3 deficient mice 4, 6 and 12 week-old. It is possible that an increase in hyaluronidase expression by granulosa cells is important for a controlled HA degradation in follicles that are not destined to ovulate and that this effect is compensated by one enzyme when the other is absent. Compensatory effects for this family of enzymes have already been attributed to explain the mild phenotype of a patient with Hyal-1 deficiency and the lack of infertility for mice deficient in sperm hyaluronidase (PH-20/Spam 1). Overall, our results suggest that the expression of hyaluronidases by ovarian granulosa cells may be associated with the process of follicular atresia. Supported by the Natural Sciences and Engineering Research Council of Canada (NSERC)

KEY WORDS: Hyaluronidase, Granulosa Cells, Atresia, Follicle Development