Involvement of the Serine Protease Inhibitor, SERPINE2, and the Urokinase Plasminogen Activator in Cumulus Expansion and Oocyte Maturation

Abstract

The serpin peptidase inhibitor, clade E, member 2 (SERPINE2) inhibits urokinase-type plasminogen activator (PLAU) and tissue-type plasminogen activator. Higher SERPINE2 expression levels were detected in cumulus cells of human immature oocytes than in those of mature oocytes. The objective of this study was to evaluate whether high SERPINE2 levels in cumulus cells are associated with oocyte immaturity. Using the mouse cumulus–oocyte complex as an experimental model, the effects of elimination and overexpression of SERPINE2 in cumulus cells on cumulus expansion and oocyte maturation were assayed by in vitro maturation. Serpine2 and PLAU transcripts were the most highly expressed serpins and plasminogen activators, respectively. Their expression was coordinately regulated in cumulus cells during gonadotropin-induced oocyte maturation. Silencing of Serpine2 expression using small interfering RNAs or blockage of SERPINE2 protein using a specific antibody had no effect on oocyte maturation. However, overexpression of Serpine2 or exogenous supplementation with high levels of SERPINE2 impaired cumulus expansion and oocyte maturation, probably by decreasing hyaluronan synthase 2 (Has2) and versican (Vcan) mRNA expression. Amiloride, a specific PLAU inhibitor, also suppressed these processes. PLAU supplementation of the oocyte in vitro maturation medium caused earlier and more extensive expansion of cumulus cells and oocyte maturation that may be mediated by increased Has2 mRNA expression. However, these effects were neutralized by coincubation with SERPINE2 or amiloride and PLAU. In conclusion, SERPINE2 and PLAU are involved in cumulus expansion and oocyte maturation. High SERPINE2 levels impair these processes, probably by decreasing cumulus matrix gene expression as well as reducing cumulus hyaluronan contents and inhibiting PLAU activity. These findings may explain why cumulus cells surrounding immature human oocytes express high SERPINE2 levels.

The serine protease inhibitors and SERPINE1/2 disrupt prostaglandin E2 production and hyaluronic acid retention in FSH‐stimulated pig cumulus–oocyte complexes

“…Since both the serine protease inhibitors and SERPINE1/2 prevent the conversion of plasminogen to plasmin, the present data argue for an important role of this serine protease in regulation of cumulus expansion in the pig. The inhibitory effect of SERPINE1/2 on HA retention observed in our study is in line with the results of a previous study in mice (Lu et al., ).…”

“…In our previous study, we documented that FSH induced in porcine cumulus cells the upregulation of genes involved in blood coagulation and fibrinolysis, such as tissue‐type plasminogen activator ( PLAT ), urokinase‐type plasminogen activator receptor ( PLAUR ) and plasminogen activator inhibitor 1 ( SERPINE1 ; Blaha, Nemcova, Kepkova, Vodicka, & Prochazka, ). PLAT and PLAUR regulate the conversion of plasminogen into the active serine protease plasmin, whereas SERPINEs inhibit PLAT and PLAU activity and hence work as inhibitors of plasmin‐related proteolytic activity (Lu et al., ).…”

“…A coordinated temporal and tissue‐specific expression of PLAT/PLAU and SERPINs exist in pre‐ovulatory follicles, so that a maximum proteolytic activity is reached at the time of ovulation, which is associated with the role of plasmin in the rupture of the follicle wall (Liu et al., ). Besides the follicular rupture, plasminogen activators and SERPINs have been shown to affect other ovarian functions (Lu et al., ). The aim of this study is to assess the effect of serine protease inhibitors (aprotinin and 4‐(2‐aminoethyl) benzenesulfonyl fluoride—AEBSF) and specific plasminogen activator inhibitors (SERPINE1/2) on pig cumulus expansion, specifically on expression of HAS2 , production of PGE2 and retention of HA in expanding cumulus.…”

Expression pattern of human SERPINE2 in a variety of human tumors

“…Indeed, it has been reported that SERPINE2 was highly expressed in the endometrium during the secretory phase compared with the proliferative phase, indicating that it may participate in tissue remodeling during implantation in the placenta and uterus (31,32). A high SERPINE2 level was found in the inhibition of cumulus expansion and oocyte maturation (33). Interestingly, chromogranin A could promote secretory granule biogenesis in endocrine cells through up-regulation of the expression of SERPINE2 via a cAMP-protein kinase A-Sp1 pathway to replenish released granules (34).…”

Derivation of Patient Specific Pluripotent Stem Cells Using Clinically Discarded Cumulus Cells

“…Limited efforts have been taken to make use of clinically discarded CCs. In one direction, gene expression patterns in CCs were used to predict the oocyte quality and consequently the developmental competency of the derivative embryos [30]. …”