Expression and localization of the serine proteases HtrA1, PRSS23, and PRSS35 in the mouse ovary. Wahlberg P et al. Proteolytic degradation of extracellular matrix components has been suggested to play an essential role for the occurrence of ovulation. Recent studies in our laboratory have indicated that the plasminogen activator and matrix metalloproteinase systems, which were previously believed to be crucial for ovulation, are not required in this process. In this study, we have used a microarray approach to identify new proteases that are involved in ovulation. We found three serine proteases that were relatively highly expressed during ovulation: HtrA1, which was not regulated much during ovulation; PRSS23, which was downregulated by gonadotropins; and PRSS35, which was upregulated by gonadotropins. We have further investigated the expression patterns of these proteases during gonadotropin-induced ovulation in immature mice and in the corpus luteum (CL) of pseudopregnant mice. We found that HtrA1 was highly expressed in granulosa cells throughout follicular development and ovulation as well as in the forming and regressing CL. PRSS23 was highly expressed in atretic follicles and it was expressed in the ovarian stroma and theca tissues just prior to ovulation. PRSS35 was expressed in the theca layers of developing follicles. It was also highly induced in granulosa cells of preovulatory follicles. PRSS35 was also expressed in the forming and regressing CL. These data suggest that HtrA1 and PRSS35 may be involved in ovulation and CL formation and regression, and that PRSS23 may play a role in follicular atresia.
Expression regulated by
Steroids
Comment
Ovarian localization
Granulosa, Theca, Luteal cells
Comment
The Identification of Novel Ovarian Proteases Through the Use of Genomic and Bioinformatic Methodologies. Miyakoshi K et al. Proteolytic activities are essential for follicular growth, ovulation, as well as luteal formation and regression. Using suppression subtractive hybridization (SSH), a novel mouse ovary-selective gene (termed protease serine 35: Prss35) was identified. Analysis of the mouse genome database using the Prss35 sequence led to the identification of a homologous protease (protease serine 23; Prss23). PRSS35 possesses general features characteristic of Ser proteases, but is unique in that the canonical Ser that defines this enzyme family is replaced by a Thr. In contrast, PRSS23 possesses the standard catalytic Ser typical for this family of proteases. As determined by real-time polymerase chain reaction (PCR), Prss35 mRNA levels increased around the time of ovulation and remained elevated in the developing corpus luteum. Steroid ablation/replacement studies demonstrated progesterone-dependent regulation of Prss35 gene expression prior to follicle rupture. Prss35 gene expression was localized to the theca cells of preantral follicles, theca and granulosa cells of preovulatory and ovulatory follicles, as well as the developing corpus luteum. In contrast, Prss23 mRNA levels decreased transiently after ovulation induction and again in the post-ovulatory period. Prss23 gene expression was noted primarily in the granulosa cells of secondary/early antral follicles. PRSS35 and PRSS23 orthologs in the rat, human, rhesus macaque, chimpanzee, bovine, dog, and chicken were identified and found to be highly homologous to one another (75-99% homology). Collectively, these results suggest that PRSS35 and PRSS23 genes have been maintained through the course of vertebrate evolution as critical ovarian proteases.