Ovulation efficiency is reduced in mice that lack plasminogen activator gene function: functional redundancy among physiological plasminogen activators

The novel stimulators of feline ovarian granulosa cell functions: Monocyte chemoattractant protein-1 and plasminogen activator inhibitor-1

The aim of the present study was to determine whether adipokines monocyte chemoattractant protein-1 (MCP-1) and plasminogen activator inhibitor-1 (PAI-1) can affect the functions of ovarian cells in cats. The addition of either MCP-1 or PAI-1 increased viability; promoted the accumulation of proliferation markers and progesterone and estradiol release; and decreased the accumulation of apoptosis markers in cultured feline granulosa cells. The present observations suggest that MCP-1 or PAI-1 can be physiological stimulators of ovarian granulosa cell functions.

The basic functions of rabbit ovarian granulosa cell are regulated by adipokines monocyte chemoattractant protein-1 and plasminogen activator inhibitor-1

The aim of the present study was to examine the influence of monocyte chemoattractant protein-1 (MCP-1) and plasminogen activator inhibitor-1 (PAI-1) on ovarian cell functions. Rabbit ovarian granulosa cells were cultured with or without MCP-1 or PAI-1 (at 0, 0.1, 1, or 10 ng/ml). Cell viability, proliferation, cytoplasmic apoptosis and release of progesterone and estradiol were measured by Cell Counting Kit-8 (CCK-8), BrdU incorporation, and cell death detection assays and ELISA. The addition of either MCP-1 or PAI-1 increased cell viability and proliferation and decreased apoptosis. MCP-1 promoted, while PAI-1 suppressed, progesterone release. Both MCP-1 and PAI-1 reduced estradiol output. The present results suggest that MCP-1 or PAI-1 can be physiological promoters of rabbit ovarian cell viability and proliferation, inhibitors of apoptosis and regulators of ovarian steroidogenesis.

Decreased fertility in female mice lacking urokinase plasminogen activator

It is well established that mouse ovarian granulosa cells secrete urokinase plasminogen activator (uPA) under gonadotropin stimulation. The synthesis and secretion of the enzyme correlate well with the time of follicular rupture in vivo. Moreover, uPA is secreted by the trophoblast at the time of implantation. In the present study, we have analyzed whether the absence of uPA could influence follicular growth, ovulation, and embryo implantation. Our data show fewer preantral follicles in uPA-/- ovaries but no decrease in hormonally induced ovulation. However, we observed a significant decrease in the number of implanted embryos in uPA-/- animals and, therefore, a lower number of pups per family. Adding uPA to the epithelial and stromal uterine cell culture medium strongly upregulates the expression of prostaglandin-endoperoxide synthase 2 (Ptgs2), the enzyme required for prostaglandin production and embryo implantation. The uPA inhibitor amiloride abrogated this increase.

An ex vivo ovulation system enables the discovery of novel ovulatory pathways and nonhormonal contraceptive candidates†

Ovulation is an integral part of women's menstrual cycle and fertility. Understanding the mechanisms of ovulation has broad implications for the treatment of anovulatory diseases and the development of novel contraceptives. Now, few studies have developed effective models that both faithfully recapitulate the hallmarks of ovulation and possess scalability. We established a three-dimensional encapsulated in vitro follicle growth (eIVFG) system that recapitulates folliculogenesis and produces follicles that undergo ovulation in a controlled manner. Here, we determined whether ex vivo ovulation preserves molecular signatures of ovulation and demonstrated its use in discovering novel ovulatory pathways and nonhormonal contraceptive candidates through a high-throughput ovulation screening. Mature murine follicles from eIVFG were induced to ovulate ex vivo using human chorionic gonadotropin and collected at 0, 1, 4, and 8 hours post-induction. Phenotypic analyses confirmed key ovulatory events, including cumulus expansion, oocyte maturation, follicle rupture, and luteinization. Single-follicle RNA-sequencing analysis revealed the preservation of ovulatory genes and dynamic transcriptomic profiles and signaling. Soft clustering identified distinct gene expression patterns and new pathways that may critically regulate ovulation. We further used this ex vivo ovulation system to screen 21 compounds targeting established and newly identified ovulatory pathways. We discovered that proprotein convertases activate gelatinases to sustain follicle rupture and do not regulate luteinization and progesterone secretion. Together, our ex vivo ovulation system preserves molecular signatures of ovulation, presenting a new powerful tool for studying ovulation and anovulatory diseases as well as for establishing a high-throughput ovulation screening to identify novel nonhormonal contraceptives for women.

Metalloproteases in gonad formation and ovulation

Changes in expression or activation of various metalloproteases including matrix metalloproteases (Mmp), a disintegrin and metalloprotease (Adam) and a disintegrin and metalloprotease with thrombospondin motif (Adamts), and their endogenous inhibitors (tissue inhibitors of metalloproteases, Timp), have been shown to be critical for ovulation in various species from studies in past decades. Some of these metalloproteases such as Adamts1, Adamts9, Mmp2, and Mmp9 have also been shown to be regulated by luteinizing hormone (LH) and/or progestin, which are essential triggers for ovulation in all vertebrate species. Most of these metalloproteases also express broadly in various tissues and cells including germ cells and somatic gonad cells. Thus, metalloproteases likely play roles in gonad formation processes comprising primordial germ cell (PGC) migration, development of germ and somatic cells, and sex determination. However, our knowledge on the functions and mechanisms of metalloproteases in these processes in vertebrates is still lacking. This review will summarize our current knowledge on the metalloproteases in ovulation and gonad formation with emphasis on PGC migration and germ cell development.

Bone morphogenetic protein 2 upregulates SERPINE2 expression through noncanonical SMAD2/3 and p38 MAPK signaling pathways in human granulosa-lutein cells

Serine protease inhibitor-E2 (SERPINE2) is highly expressed in the granulosa cells of growing follicles and the dynamic changes in SERPINE2 expression are correlated with follicular development and ovulation in several mammals, including mice, cattle, sheep, and humans. Bone morphogenetic proteins (BMPs) and their functional receptors are extensively expressed in the ovary and play critical roles in the regulation of ovarian folliculogenesis and luteal function. To date, whether BMPs regulate the expression of SERPINE2 during human follicular development remains to be elucidated. The aim of this study was to investigate the effects of BMPs on the regulation of SERPINE2 expression (a major regulator of plasminogen activators [PA]) and the underlying mechanisms using primary and immortalized human granulosa-lutein (hGL) cells. Our results demonstrated that these BMPs (BMP2, BMP4, BMP6, BMP7, and BMP15) induced differential upregulation of SERPINE2 expression. In this regard, BMP2 is the major modulator that has the best cellular activity, which further decreased the production of urokinase PA and tissue PA in hGL cells. In addition to canonical SMAD1/5/8 signaling, BMP2 also activates noncanonical SMAD2/3 and p38 mitogen-activated protein kinase (MAPK) signaling. Using two inhibition approaches (kinase receptor inhibitors and siRNA-mediated knockdown), we found that SMAD2/3-SMAD4 and p38 MAPK, but not SMAD1/5/8 signaling, was involved in the BMP2-induced upregulation of SERPINE2 expression via activin receptor-like kinase 3. These findings deepen our understanding of the differential effect of BMPs in regulating follicular function and provide new insights of the molecular mechanisms by which BMP2 regulates the expression of SERPINE2 in human granulosa cells.

Ovulation is Inhibited by an Environmentally Relevant Phthalate Mixture in Mouse Antral Follicles In Vitro

Phthalates are solvents and plasticizers found in consumer products including cosmetics, food/beverage containers, housing materials, etc. Phthalates are known endocrine-disrupting chemicals that can directly target the ovary, potentially causing defects in ovulation and fertility. Women are exposed to multiple different phthalates daily, therefore this study investigated the effects of an environmentally relevant phthalate mixture (PHTmix) on ovulation. Ovulation is initiated by the luteinizing hormone (LH) surge, which induces prostaglandin (PG) production, progesterone (P4)/progesterone receptor (PGR) signaling, and extracellular matrix (ECM) remodeling. We hypothesized that the PHTmix would directly inhibit ovulation by altering the levels of PGs, P4/PGR, and enzymes involved in ECM remodeling. Antral follicles from CD-1 mice were treated with vehicle control alone (dimethylsulfoxide, DMSO), hCG alone (LH analog), and hCG+PHTmix (1-500μg/ml), and samples were collected across the ovulatory period. The PHTmix decreased ovulation rates at all doses tested in a dose-dependent manner when compared to hCG. PG levels were decreased by the PHTmix when compared to hCG, which was potentially mediated by altered levels of PG synthesis (Ptgs2) and transport (Slco2a1) genes. The PHTmix altered P4 and Pgr levels when compared to hCG, leading to decreases in downstream PGR-mediated genes (Edn2, Il6, Adamts1). ECM remodeling was potentially dysregulated by altered levels of ovulatory mediators belonging to the matrix metalloproteases and plasminogen activator families. These data suggest that phthalate exposure inhibits ovulation by altering PG levels, P4/PGR action, and ECM remodeling.

Transcriptome analysis to unravel the gene expression profile of ovarian follicular development in Magang goose

Magang geese exhibit a unique characteristic of follicular development, with eight largest orderly arranged pre-ovulatory follicles in the abdominal cavity. However, little is known about the mechanisms underlying this follicular development. This study aimed to compare gene expression profiles of granulosa cells (GCs) at different stages of follicular development and provide comprehensive insights into follicle selection and the mechanisms underlying the well-defined follicle hierarchy in Magang geese. GCs of large white follicles (LWFs), small yellow follicles (SYFs), F8, F4, and F1 were used for RNA-seq analysis; 374, 1117, 791, and 593 genes were differentially expressed in stages LWFs to SYFs, SYFs to F8, F8 to F4, and F4 to F1, respectively, suggesting that these genes contribute to follicle selection and development. Reliability of sequencing data was verified through qPCR analysis of 24 genes. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathways revealed a complex mechanism that remodels the extracellular matrix and turnover of extracellular matrix components in follicular development and ovulation and involves multiple pathway, such as focal adhesion, adherens junction, and extracellular matrix–receptor interaction. Some unique characteristics were observed during the different follicular development stages. For instance, some differentially expressed genes were enriched in progesterone-mediated oocyte maturation and steroid biosynthesis from stage SYFs to F8, whereas others were enriched in actin cytoskeleton regulation and vascular smooth muscle contraction from stage F4 to F1. These findings enhance our current understanding of GC function and ovarian follicles during the key stages of follicular development.

Inherited disorders of the fibrinolytic pathway

Deficiencies or excessive activation of the  fibrinolytic system can result in severe, lifelong bleeding disorders. The most severe clinical phenotype is caused by α2-Antiplasmin (α2-AP) deficiency which results in excess fibrinolysis due to the inability to inhibit plasmin. Another bleeding disorder due to a defect in the fibrinolytic pathway results from Plasminogen activator inhibitor-1 (PAI-1) deficiency causing enhanced fibrinolysis due to the decreased inhibition of plasminogen activators resulting in increased conversion of plasminogen to plasmin. Both these disorders are rare and have an autosomal recessive pattern of inheritance. They can remain undetected as routine coagulation and platelet function tests are normal. A unique gain-of-function defect in fibrinolysis causes the Quebec platelet disorder (QPD) which is characterized by profibrinolytic platelets containing increased urokinase-type plasminogen activator (uPA) in the α-granules. A high index of suspicion based on clinical phenotype along with the availability of specialized hemostasis testing is required for timely and accurate diagnosis. Antifibrinolytic agents, such as tranexamic acid or ε-aminocaproic acid, are the mainstays of treatment which inhibit fibrinolysis by preventing the binding of plasminogen to fibrin and thereby stabilizing the fibrin clot. The purpose of this review is to summarize the pathogenesis, clinical phenotype, approaches to diagnosis and treatment for these three major disorders of fibrinolysis.

The endogenous hydrogen sulfide generating system regulates ovulation

The generation of free-radicals such as nitric oxide has been implicated in the regulation of ovarian function, including ovulation. Tissues that generate nitric oxide typically generate another free-radical gas, hydrogen sulfide (H₂S), although little is known about the role of H₂S in ovarian function. The hypothesis of this study was that H₂S regulates ovulation. Treatment with luteinizing hormone (LH) increased the levels of mRNA and protein of the H₂S generating enzyme cystathionine γ-lyase (CTH) in granulosa cells of mice and humans in vivo and in vitro. Pharmacological inhibition of H₂S generating enzymes reduced the number of follicles ovulating in mice in vivo and in vitro, and this inhibitory action was reversed by cotreatment with a H₂S donor. Addition of a H₂S donor to cultured mouse granulosa cells increased basal and LH-dependent abundance of mRNA encoding amphiregulin, betacellulin and tumor necrosis alpha induced protein 6, proteins important for cumulus expansion and follicle rupture. Inhibition of CTH activity reduced abundance of mRNA encoding matrix metalloproteinase-2 and -9 and tissue-type plasminogen activator, and cotreatment with the H₂S donor increased the levels of these mRNA above those stimulated by LH alone. We conclude that the H₂S generating system plays an important role in the propagation of the preovulatory cascade and rupture of the follicle at ovulation.

Ovulation: Parallels With Inflammatory Processes

The midcycle surge of LH sets in motion interconnected networks of signaling cascades to bring about rupture of the follicle and release of the oocyte during ovulation. Many mediators of these LH-induced signaling cascades are associated with inflammation, leading to the postulate that ovulation is similar to an inflammatory response. First responders to the LH surge are granulosa and theca cells, which produce steroids, prostaglandins, chemokines, and cytokines, which are also mediators of inflammatory processes. These mediators, in turn, activate both nonimmune ovarian cells as well as resident immune cells within the ovary; additional immune cells are also attracted to the ovary. Collectively, these cells regulate proteolytic pathways to reorganize the follicular stroma, disrupt the granulosa cell basal lamina, and facilitate invasion of vascular endothelial cells. LH-induced mediators initiate cumulus expansion and cumulus oocyte complex detachment, whereas the follicular apex undergoes extensive extracellular matrix remodeling and a loss of the surface epithelium. The remainder of the follicle undergoes rapid angiogenesis and functional differentiation of granulosa and theca cells. Ultimately, these functional and structural changes culminate in follicular rupture and oocyte release. Throughout the ovulatory process, the importance of inflammatory responses is highlighted by the commonalities and similarities between many of these events associated with ovulation and inflammation. However, ovulation includes processes that are distinct from inflammation, such as regulation of steroid action, oocyte maturation, and the eventual release of the oocyte. This review focuses on the commonalities between inflammatory responses and the process of ovulation.

Tissue plasminogen activator (tPA) of paternal origin is necessary for the success of in vitro but not of in vivo fertilisation in the mouse

Besides its fibrinolytic function, the plasminogen–plasmin (PLG–PLA) system is also involved in fertilisation, where plasminogen activators bind to plasminogen to produce plasmin, which modulates sperm binding to the zona pellucida. However, controversy exists, depending on the species, concerning the role of the different components of the system. This study focused its attention on the role of the PLG–PLA system on fertilisation in the mouse with special attention to tissue plasminogen activator (tPA). The presence of exogenous plasminogen reduced invitro fertilisation (IVF) rates and this decline was attenuated by the presence of plasmin inhibitors in combination with plasminogen. The incubation of spermatozoa with either oocytes or cumulus cells together with plasminogen did not change the acrosome reaction but reduced the number of spermatozoa attached. When spermatozoa from tPA−/− mice were used, the IVF rate decreased drastically, although the addition of exogenous tPA during gamete co-incubation under invitro conditions increased fertilisation success. Moreover, fertility could not be restored after invivo insemination of tPA−/− spermatozoa in the female ampulla, although tPA−/− males were able to fertilise invivo. This study suggests a regulatory role of the PLG–PLA system during fertilisation in the mouse with possible implications in human reproduction clinics, such as failures in tPA production, which could be partially resolved by the addition of exogenous tPA during IVF treatment.

Urokinase-type plasminogen activator modulates mammalian circadian clock phase regulation in tissue-type plasminogen activator knockout mice

Glutamate phase shifts the circadian clock in the mammalian suprachiasmatic nucleus (SCN) by activating NMDA receptors. Tissue-type plasminogen activator (tPA) gates phase shifts by activating plasmin to generate m(ature) BDNF, which binds TrkB receptors allowing clock phase shifts. Here, we investigate phase shifting in tPA knockout (tPA^-/- ; B6.129S2-Plat^tm1Mlg /J) mice, and identify urokinase-type plasminogen activator (uPA) as an additional circadian clock regulator. Behavioral activity rhythms in tPA^-/- mice entrain to a light-dark (LD) cycle and phase shift in response to nocturnal light pulses with no apparent loss in sensitivity. When the LD cycle is inverted, tPA^-/- mice take significantly longer to entrain than C57BL/6J wild-type (WT) mice. SCN brain slices from tPA^-/- mice exhibit entrained neuronal activity rhythms and phase shift in response to nocturnal glutamate with no change in dose-dependency. Pre-treating slices with the tPA/uPA inhibitor, plasminogen activator inhibitor-1 (PAI-1), inhibits glutamate-induced phase delays in tPA^-/- slices. Selective inhibition of uPA with UK122 prevents glutamate-induced phase resetting in tPA^-/- but not WT SCN slices. tPA expression is higher at night than the day in WT SCN, while uPA expression remains constant in WT and tPA^-/- slices. Casein-plasminogen zymography reveals that neither tPA nor uPA total proteolytic activity is under circadian control in WT or tPA^-/- SCN. Finally, tPA^-/- SCN tissue has lower mBDNF levels than WT tissue, while UK122 does not affect mBDNF levels in either strain. Together, these results suggest that either tPA or uPA can support photic/glutamatergic phase shifts of the SCN circadian clock, possibly acting through distinct mechanisms.

Correlation of cumulus gene expression of GJA1, PRSS35, PTX3, and SERPINE2 with oocyte maturation, fertilization, and embryo development

BACKGROUND

GJA1 and PTX3 were proposed as gene markers for oocyte and embryo developmental competence, while SERPINE2 was reported to be associated with pregnancy outcome. PRSS35, which is exclusively expressed in the ovary, may be correlated with oocyte competence. This study was conducted to evaluate the correlation of cumulus GJA1, PRSS35, PTX3, and SERPINE2 gene expression levels with oocyte maturation, fertilization, and early embryo development.

METHODS

In total, 308 cumulus cell samples separated from individual cumulus-oocyte complex were obtained from 40 patients undergoing the intracytoplasmic sperm injection treatment procedure. Gene expression levels (mRNA levels) in cumulus cells were assessed using quantitative real-time polymerase chain reaction.

RESULTS

Gene expression levels of GJA1 and SERPINE2 in cumulus cells surrounding mature oocytes were significantly lower than those in cumulus cells enclosing immature oocytes. PRSS35 mRNA levels in cumulus cells of fertilized oocytes were significantly higher than those in cumulus cells of unfertilized oocytes. GJA1 and SERPINE2 seemed to express higher mRNA levels, while PRSS35 showed lower expression in cumulus cells of oocytes that developed into embryos with good morphology; however, the expression levels of all three genes and PTX3 showed no significant differences between embryos with good or poor morphology.

CONCLUSIONS

GJA1 and SERPINE2 represent potential gene markers associated with oocyte maturation. PRSS35 may be correlated with oocyte fertilization potential. However, GJA1, PRSS35, PTX3, and SERPINE2 may not be considered as marker genes for predicting embryo morphology.

Engineering the ovarian cycle using in vitro follicle culture

STUDY QUESTION

Can cultured follicles model the ovarian cycle, including follicular- and luteal-phase hormone synthesis patterns and ovulation?

SUMMARY ANSWER

Under gonadotrophin stimulation, murine follicles grown in an encapsulated three-dimensional system ovulate in vitro and murine and human follicle hormone synthesis mimics follicular and luteal phases expected in vivo.

WHAT IS KNOWN ALREADY

Studies of the human ovary and follicle function are limited by the availability of human tissue and lack of in vitro models. We developed an encapsulated in vitro follicle growth (eIVFG) culture system, which preserves 3D follicular structure. Thus far, the alginate system has supported the culture of follicles from mice, dog, rhesus macaque, baboon and human. These studies have shown that cultured follicles synthesize steroid hormones similar to those observed during the follicular phase in vivo.

STUDY DESIGN, SIZE, DURATION

Cultured murine follicles were treated with human chorionic gonadotrophin (hCG) and epidermal growth factor (EGF) and either assayed for luteinization or removed from alginate beads and assayed for ovulation. Human follicles were also cultured, treated with follicle-stimulating hormone (FSH), hCG and EGF to mimic gonadotrophin changes throughout the ovarian cycle, and culture medium was assayed for hormone production.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Murine and human follicles were cultured in alginate hydrogel and hormone production [17β-estradiol, progesterone, inhibin A, inhibin B, activin A and anti-Müllerian hormone (AMH)] was quantified in medium by enzyme-linked immuno assay (ELISA). Human ovarian tissue was acquired from females between 6 and 34 years of age with a cancer diagnosis. These participants were undergoing ovarian tissue cryopreservation at National Physicians Cooperative sites as part of the Oncofertility Consortium.

MAIN RESULTS AND THE ROLE OF CHANCE

When grown in this system, 96% of mouse follicles ovulated in response to hCG and released meiotically competent eggs. Ovulated follicles recapitulated transcriptional, morphologic and hormone synthesis patterns post-luteinizing hormone (LH/hCG). In addition to rodent follicles, individual human follicles secreted steroid and peptide hormones that mimicked the patterns of serum hormones observed during the menstrual cycle.

LIMITATIONS, REASONS FOR CAUTION

This was a descriptive study of an in vitro model of ovulation and the ovarian hormone cycle. The ovulation studies were limited to murine tissue and further studies are needed to optimize conditions using other species.

WIDER IMPLICATIONS OF THE FINDINGS

The eIVFG system reliably phenocopies the in vivo ovarian cycle and provides a new tool to study human follicle biology and the influence of cycling female hormones on other tissue systems in vitro.

STUDY FUNDING/COMPETING INTERESTS

This work was supported by NIH U54 HD041857, NIH U54 HD076188, NIH UH2 E5022920, NIH UH3 TR001207 and F30 AG040916 (R.M.S.). The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH. The funders had no role in study design, data collection and analysis, decision to publish or preparation of the manuscript.

Periodicity in the levels of serum plasminogen activator inhibitor-1 is a robust prognostic factor for embryo implantation and clinical pregnancy in ongoing IVF cycles

CONTEXT:

Plasminogen activator inhibitor-1 (PAI-1) has been inversely correlated to proteolytic extracellular-matrix degradation exerted by urokinase-type (u-PA) and tissue-type plasminogen activators (t-PA). Any pathological disturbance in PAI-1 levels may lead to several pregnancy complications.

AIMS:

To assess the influence of periodicity in serum PAI-1 levels on embryo implantation and clinical pregnancy outcome in IVF cycles

SETTINGS AND DESIGN:

Prospective study of 120 IVF cycles at private infertility centre.

MATERIAL AND METHODS:

Endometrial response (ER) assessment by measuring Endometrial thickness (cm) and echopattern (grade). Serum PAI-1(ng/ml) measurement by ELISA method on day of hCG, day of ET and days 7 and 14 of ET. Main outcome measure was clinical pregnancy.

STATISTICAL ANALYSIS:

Student “t” test, ANOVA, Post-test for linear trend, Pearson Correlation.

RESULTS:

PAI-1 levels declined from dhCG to dET (318.8 ± 36.1 to 176.1 ± 28.4) whereas they increased steadily from dET to d7 to d14ET (176.1 ± 28.4 to 285.2 ± 30.4 to 353.5 ± 150.4; P = 0.0004) in pregnant group (n = 31). Conversely, dhCG to dET levels increased in both nonpregnant (n = 75; 173.8 ± 18.3 to 280.8 ± 26.1) and biochemical pregnancy BCP (n = 14; 172.7 ± 31.1 to 216 ± 30.1) groups. The rising pattern from dET to d7 to d14ET was not observed in non-pregnant and BCP groups. ER thickness and grade shared significant correlation with serum PAI-1 on dET (Pearson r: ER = 0.28, Grade = 0.29) and d7ET (Pearson r: ER = 0.40, Grade = 0.23).

CONCLUSIONS:

Periodicity in serum PAI-1 levels offers a robust prognostic factor for predicting clinical pregnancy outcome. The dhCG to dET PAI-1 transition is a decisive factor for either transferring embryos in same/ongoing cycle or cryopreserving them and postponing ET to subsequent natural cycle.

Involvement of the serine protease inhibitor, SERPINE2, and the urokinase plasminogen activator in cumulus expansion and oocyte maturation

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.

Differential gene expression of granulosa cells after ovarian superstimulation in beef cattle

Microarray analysis was used to compare the gene expression of granulosa cells from dominant follicles with that of those after superstimulatory treatment. Cows were allocated randomly to two groups (superstimulation and control, n=6/group). A new follicular wave was induced by ablation of follicles ≥5 mm in diameter, and a progesterone-releasing device controlled internal drug release (CIDR) was placed in the vagina. The superstimulation group was given eight doses of 25 mg FSH at 12-h intervals starting from the day of wave emergence (day 0), whereas the control group was not given FSH treatment. Both groups were given prostaglandin F2α twice, 12 h apart, on day 3 and the CIDR was removed at the second injection; 25 mg porcine luteinizing hormone (pLH) was given 24 h after CIDR removal, and cows were ovariectomized 24 h later. Granulosa cells were collected for RNA extraction, amplification, and microarray hybridization. A total of 190 genes were downregulated and 280 genes were upregulated. To validate the microarray results, five genes were selected for real-time PCR (NTS, FOS, THBS1, FN1, and IGF2). Expression of four genes increased significantly in the three different animals tested (NTS, FOS, THBS1, and FN1). The upregulated genes are related to matrix remodeling (i.e. tissue proliferation), disturbance of angiogenesis, apoptosis, and oxidative stress response. We conclude that superstimulation treatment i) results in granulosa cells that lag behind in maturation and differentiation (most of the upregulated genes are markers of the follicular growth stage), ii) activates genes involved with the NFE2L2 oxidative stress response and endoplasmic reticulum stress response, and iii) disturbs angiogenesis.

Effect of porcine follicular fluid proteins and peptides on oocyte maturation and their subsequent effect on in vitro fertilization

The follicular fluid (FF) is a microenvironment that contains molecules involved in oocyte maturation, ovulation, and fertilization. Characterizing the proteins and peptides present in the FF could be useful for determining which proteins and peptides to use as a supplement for culture media. Biologically active peptides produced during the maturation or degradation of functional proteins are called cryptides. The aim of this study was to identify the proteins and cryptides in porcine FF that could stimulate porcine oocyte in vitro maturation (IVM) and in vitro fertilization (IVF) when added to culture maturation medium. Five FF protein fractions (F1-F5) were obtained by ionic exchange chromatography, resolved by SDS-PAGE, and identified by tandem mass spectrometry. These fractions had effects on IVM and/or IVF. The F1 fraction, which was composed of immunoglobulin fragments, cytokeratin, transferrin, and plasminogen precursor increased IVM and IVF. The F2, F3, and F4 fractions reduced the percentage of oocytes in first metaphase. Additionally, the F3 fraction, which was composed of immunoglobulins and transthyretin, interfered with germinal vesicle breakdown. The F5 fraction, which was mainly composed of serum albumin and keratin, favored germinal vesicle breakdown and promoted IVM. Most of the 31 proteins which were associated with the immune response and inflammatory processes could be related to oocyte maturation and fertilization. Some of the identified proteins were present in more than one fraction; this could be explained by a change in their isoelectric points, because of the loss of part of the amino acid sequence or a change in the glycosylation status of the protein. Improved oocyte IVM and IVF will increase embryo production, which in turn will contribute to the efficiency of assisted reproduction in various mammalian species.

Systematic analysis of protease gene expression in the rhesus macaque ovulatory follicle: metalloproteinase involvement in follicle rupture

Protease genes were identified that exhibited increased mRNA levels before and immediately after rupture of the naturally selected, dominant follicle of rhesus macaques at specific intervals after an ovulatory stimulus. Quantitative real-time PCR validation revealed increased mRNA levels for matrix metalloproteinase (MMP1, MMP9, MMP10, and MMP19) and a disintegrin and metalloproteinase with thrombospondin-like repeats (ADAMTS1, ADAMTS4, ADAMTS9, and ADAMTS15) family members, the cysteine protease cathepsin L (CTSL), the serine protease urokinase-type plasminogen activator (PLAU), and the aspartic acid protease pepsinogen 5 (PGA5). With the exception of MMP9, ADAMTS1, and PGA5, mRNA levels for all other up-regulated proteases increased significantly (P < 0.05) 12 h after an ovulatory human chorionic gonadotropin (hCG) bolus. MMP1, -10, and -19; ADAMTS1, -4, and -9; CTSL; PLAU; and PGA5 also exhibited a secondary increase in mRNA levels in 36-h postovulatory follicles. To further determine metalloproteinase involvement in ovulation, vehicle (n = 4) or metalloproteinase inhibitor (GM6001, 0.5 μg/follicle, n = 8) was injected into the preovulatory follicle at the time of hCG administration. Of the eight GM6001-injected follicles, none displayed typical stigmata indicative of ovulation at 72 h after hCG; whereas all four vehicle-injected follicles ovulated. No significant differences in mean luteal progesterone levels or luteal phase length occurred between the two groups. Subsequent histological analysis revealed that vehicle-injected follicles ruptured, whereas GM6001-injected follicles did not, as evidenced by an intact stroma and trapped oocytes (n = 3). These findings demonstrate metalloproteinases are critical for follicle rupture in primates, and blocking their activity would serve as a novel, nonhormonal means to achieve contraception.

Concomitant lack of MMP9 and uPA disturbs physiological tissue remodeling

Urokinase-type plasminogen activator (uPA) and matrix metalloproteinase-9 (MMP9, gelatinase B) have separately been recognized to play important roles in various tissue remodeling processes. In this study, we demonstrate that deficiency for MMP9 in combination with ablation of either uPA- or tissue-type plasminogen activator (tPA)-catalyzed plasminogen activation is critical to accomplish normal gestation in mice. Gestation was also affected by simultaneous lack of MMP9 and the uPA receptor (uPAR). Interestingly, uPA-deficiency additionally exacerbated the effect of MMP9-deficiency on bone growth and an additive effect caused by combined lack in MMP9 and uPA was observed during healing of cutaneous wounds. By comparison, MMP9-deficiency combined with absence of either tPA or uPAR resulted in no significant effect on wound healing, indicating that the role of uPA during wound healing is independent of uPAR, when MMP9 is absent. Notably, compensatory upregulation of uPA activity was seen in wounds from MMP9-deficient mice. Taken together, these studies reveal essential functional dependency between MMP9 and uPA during gestation and tissue repair.

Glucocorticoid suppression of intraovarian levels of prostaglandins and plasminogen activator activity at ovulation in the rat ovary

AIM

Ovulation is a local physiological inflammatory process with active participation of inflammatory mediators and immune cells. To prevent extensive inflammatory injury to the follicle at ovulation there is also a local anti-inflammatory system at ovulation, converting the inactive glucocorticoid cortisone to the more potent cortisol. The aim of this study was to examine the effects of the potent glucocorticoid analogue, dexamethasone (DEX), on ovulation rate and the ovarian production of the ovulatory mediators prostaglandins (PG) and plasminogen activators (PA).

METHODS

DEX (0.3, 3, or 100 microM) was administered to an in vitro rat ovarian perfusion system prior to the addition of an ovulation-inducing dose of luteinizing hormone (LH) and 3-isobutyl-1-methylxanthine (IBMX). Control ovaries were perfused only with LH + IBMX. Each perfusion experiment extended over 20 h with ovulation occurring in vitro around 12-15 h after hormonal stimulation. In a second set of perfusion experiments, extending over 10 h, the tissue levels of PG and PA activity in the ovary were evaluated at a time 2-5 h before anticipated ovulation.

RESULTS

The median numbers of ovulated oocytes in the groups with DEX of 0.3, 3, and 100 microM were 17.0, 8.5 and 11.0 per treated ovary, respectively. These numbers were not different from those of LH + IBMX-controls (12.5). DEX (100 microM) suppressed tissue levels of PGE(2) and PA activity and decreased (DEX 3 microM, 100 microM) estradiol levels in the perfusion media.

CONCLUSION

These results indicate that certain degrees of suppression of PG, PA activity, and estradiol are not sufficient to modulate ovulation rate and/or that glucocorticoids may positively modulate other mediator pathways that exert inhibitory influence on ovulation.

Increased expression of heat shock protein 105 in rat uterus of early pregnancy and its significance in embryo implantation

BACKGROUND

Heat shock proteins (Hsps) are a set of highly conserved proteins, Hsp105, has been suggested to play a role in reproduction.

METHODS

Spatio-temporal expression of Hsp105 in rat uterus during peri-implantation period was examined by immunohistochemistry and Western blot, pseudopregnant uterus was used as control. Injection of antisense oligodeoxynucleotides to Hsp105 into pregnant rat uteri was carried out to look at effect of Hsp105 on embryo implantation.

RESULTS

Expression of Hsp105 was mainly in the luminal epithelium on day 1 of pregnancy, and reached a peak level on day 5, whereas in stroma cells, adjacent to the implanting embryo, the strongest expression of Hsp105 was observed on day 6. The immunostaining profile in the uterus was consistent with that obtained by Western blot in the early pregnancy. In contrast, no obvious peak level of Hsp105 was observed in the uterus of pseudopregnant rat on day 5 or day 6. Furthermore, injection of antisense oligodeoxynucleotides to Hsp105 into the rat uterine horn on day 3 of pregnancy obviously suppressed the protein expression as expected and reduced number of the implanted embryos as compared with the control.

CONCLUSION

Temporal and spatial changes in Hsp105 expression in pregnant rat uterus may play a physiological role in regulating embryo implantation.

Prostaglandin E2 acts via multiple receptors to regulate plasminogen-dependent proteolysis in the primate periovulatory follicle

The ovulatory gonadotropin surge regulates expression of plasminogen activator (PA) family members within the ovarian follicle, which are implicated in follicle wall degradation at ovulation. Gonadotropin also stimulates follicular prostaglandin E2 (PGE2) production, which is required for follicle rupture. To determine whether the ovulatory gonadotropin surge regulates PA-mediated proteolysis via PGE2 in the primate follicle, monkeys received gonadotropins to stimulate follicle development. Follicular aspirates or whole ovaries were obtained before (0 h) and after human chorionic gonadotropin (hCG) administration to span the periovulatory interval. Granulosa cell levels of tissue-type PA (tPA) and PA inhibitor type 1 (PAI-1) proteins were low at 0 h hCG and higher after hCG administration. In situ zymography showed no ovarian tPA activity 0 h after hCG; tPA activity was present in granulosa cells obtained after hCG treatment. Importantly, tPA and PAI-1 proteins and tPA activity were low/nondetectable in granulosa cells obtained after treatment with hCG and the PG synthesis inhibitor celecoxib. To determine whether hCG stimulation of tPA and PAI-1 requires PGE2, granulosa cells obtained at 0 h were cultured with hCG plus indomethacin to inhibit PG production; some cells also received PGE2 or an agonist selective for one PGE2 receptor (EP). PGE2, an EP2 agonist, and an EP3 agonist increased tPA protein, whereas PGE2, an EP1 agonist, and an EP3 agonist increased PAI-1 protein. Therefore, gonadotropin increases granulosa cell tPA and PAI-1 protein levels and tPA-dependent proteolytic activity. PGE2 also increases tPA and PAI-1 protein levels in granulosa cells, suggesting that elevated PGE2 late in the periovulatory interval acts to stimulate proteolysis and follicle rupture.

Male fertility and protein C inhibitor/plasminogen activator inhibitor-3 (PCI): localization of PCI in mouse testis and failure of single plasminogen activator knockout to restore spermatogenesis in PCI-deficient mice

OBJECTIVE

To investigate the mechanisms responsible for the testicular abnormalities and infertility of previously generated male protein C inhibitor (PCI)-deficient mice.

DESIGN

Determination of the localization of PCI in the reproductive organs of wild-type males. Generation of double knockout mice lacking the protease inhibitor PCI and one plasminogen activator, either urokinase (uPA) or tissue plasminogen activator (tPA), both of which are PCI-target proteases.

SETTING

Animal research and histologic analysis.

ANIMAL(S)

Male mice of desired genotype.

INTERVENTION(S)

Fertility testing of double knockout mice.

MAIN OUTCOME MEASURE(S)

Infertility of PCI(-/-)uPA(-/-) and PCI(-/-)tPA(-/-) double knockout mice.

RESULT(S)

In the testes of wild-type males PCI was detected in spermatocytes of prophase I, as well as in late spermatids and mature spermatozoa, but absent from somatic cells. All PCI(-/-) uPA(-/-) and PCI(-/-) tPA(-/-) male mice were infertile and histologic analysis of testis showed similar alterations as previously described for PCI(-/-) mice.

CONCLUSION(S)

The abnormal spermatogenesis of PCI (plasminogen activator inhibitor-3)-deficient mice cannot be rescued by single plasminogen activator knockout.

Developmental changes of FSH-R, LH-R, ER-β and GnRH-I expression in the ovary of prepubertal ducks (Anas platyrhynchos)

Normal ovarian development is dependent on stimulation of the gonadotropic hormones, follicle-stimulating hormone (FSH) and luteinizing hormone (LH), as well as some regulatory factors locally produced in ovary, e.g. 17beta-estradiol (E2) and gonadotropin-releasing hormone (GnRH), mediated by their respective receptors. In order to elucidate the potential roles of LH, FSH, E2 and GnRH-I during early follicular development in prepubertal ducks, mRNA expression of LH-R, FSH-R, ER-beta and GnRH-I in ovaries of 1-day-old (D1), 30-day-old (D30), 60-day-old (D60) and 90-day-old (D90) ducks was measured with semi-quantitative RT-PCR using beta-actin as an internal standard. The ovary index (the ratio of ovary weight/body mass) did not change from D30 to D90, while the ovary weight and serum E2 levels rose progressively, indicating the prepubertal development of the ovary. Ovarian expression of FSH-R, LH-R, ER-beta and GnRH-I mRNA changed greatly during this period. Abundance of FSH-R and ER-beta mRNA went up gradually from D1 to D60, followed by a decline on D90. LH-R and GnRH-I mRNA expression increased from D1 to D90, reaching a peak at D90. These results indicate that the developing ovary is highly responsive to the regulation of FSH during the early stage, while close to the onset of sexual maturation, the ovary is likely more responsive to LH. In addition, the expression of GnRH-I and ER-beta mRNA in the ovary suggest that GnRH-I and E2 are involved in the regulation of prepubertal follicular development in the ovary of ducks.

A guide to murine fibrinolytic factor structure, function, assays, and genetic alterations

The components and functions of the murine fibrinolytic system are quite similar to those of humans. Because of these similarities and the adaptability of mice to genetic manipulation, murine fibrinolysis has been studied extensively. These studies have yielded important information regarding the function of the several components of fibrinolysis. This review presents information on the structure, function and assay of mouse fibrinolytic parameters and it discusses the results of the extensive studies of genetically modified mice. It is intended to be a convenient reference resource for investigators of fibrinolysis.

Hepatocyte growth factor acts as a motogen and guidance signal for gonadotropin hormone-releasing hormone-1 neuronal migration

Reproduction in mammals is under the control of the hypothalamic neuropeptide gonadotropin hormone-releasing hormone-1 (GnRH-1). GnRH-1-secreting neurons originate during embryonic development in the nasal placode and migrate into the forebrain along olfactory nerves. Gradients of secreted molecules may play a role in this migratory process. In this context, hepatocyte growth factor (HGF) is a potential candidate, because it promotes cell motility in developing brain and has been shown previously to act as a motogen on immortalized GnRH-1 neurons (GN11). In this study, the role of HGF and its receptor Met during development of the GnRH-1 system was examined. GnRH-1 cells express Met during their migration and downregulate its expression once they complete this process. Tissue-type plasminogen activator (tPA), a known HGF activator, is also detected in migratory GnRH-1 neurons. Consistent with in vivo expression, HGF is present in nasal explants, and GnRH-1 neurons express Met. HGF-neutralizing antibody was applied to explants to examine the role of the endogenous growth factor. Migration of GnRH-1 cells and olfactory axon outgrowth were significantly reduced, in line with disruption of a guidance gradient. Exogenous application of HGF to explants increased the distance that GnRH-1 cells migrated, suggesting that HGF also acts as a motogen to GnRH-1 neurons. Functional experiments, performed on organotypic slice cultures, show that creation of an opposing HGF gradient inhibits GnRH-1 neuronal migration. Finally, tPA(-/-):uPA(-/-) (urokinase-type plasminogen activator(-/-)) knock-out mice exhibit strong reduction of the GnRH-1 cell population. Together, these data indicate that HGF signaling via Met receptor influences the development of GnRH-1.

Molecular pathways regulating EGF-induced epithelio-mesenchymal transition in human ovarian surface epithelium

The ovarian surface epithelium (OSE) is the precursor of common epithelial ovarian carcinomas. In the present study, we examined the molecular mechanisms and possible physiological basis for the propensity of OSE cells to undergo epithelio-mesenchymal transition (EMT) in response to environmental influences. We hypothesized that EMT may be a homeostatic mechanism that permits displaced OSE to assume a stromal phenotype within the ovarian cortex. We report that EGF in conjunction with hydrocortisone is the EMT-inducing factor of OSE as shown by changes to a fibroblast-like morphology and growth pattern. EGF increased cell motility, enhanced the activities of secreted pro-matrix metalloproteinase (MMP)-2 and -9, and enhanced expression and activation of Erk and integrin-linked kinase (ILK). Increased ILK expression correlated with the activation of PKB/Akt, the phosphorylation of GSK-3β, and the increased expression of cyclin E and cdk2 kinase. EGF withdrawal resulted in a more epithelial morphology and reversal of the EGF-induced activation of signaling pathways and pro-MMP activity. In contrast, treatment of EGF-treated cells with specific inhibitors of phosphatidylinositol 3-kinase, Mek, or ILK inhibited the inhibitor-specific pathways. The inhibitors caused suppression of EGF-induced migration and pro-MMP-2/-9 activities but did not lead to any change in EGF-induced mesenchymal morphology. ILK small interfering RNA inhibited Akt phosphorylation and reduced pro-MMP-2/-9 activities but had no effect on Erk activation or cell morphology. These results indicate that the EGF-induced morphological and functional changes in OSE cells are controlled by distinct signaling mechanisms working in concert. EMT of OSE cells displaced by ovulation likely permits their survival and integration with a fibroblast-like identity within the stroma. Failure to do so may lead to the formation of epithelium-derived inclusion cysts, which are known preferential sites of malignant transformation.

Successful ovulation in plasminogen-deficient mice treated with the broad-spectrum matrix metalloproteinase inhibitor galardin

Many studies have suggested the hypothesis that the plasminogen activator (PA) system and the matrix metalloproteinase (MMP) system, either separately or in combination, may provide the proteolytic activity that is required for rupture of the follicular wall at the time of ovulation. Our recent studies on ovulation in plasminogen (plg)-deficient mice have, however, shown that plasmin is not required for normal ovulation, leading us to the hypothesis that MMPs may be a more important source of proteolysis for this process. To investigate the role of MMPs and also the possibility of a functional overlap or synergy between the MMP and PA systems during ovulation, we have studied ovulation efficiency in wild-type and plg-deficient mice treated with the broad-spectrum MMP inhibitor galardin. We found that in both wild-type mice and heterozygous plg-deficient (plg+/-) mice that had been treated with galardin prior to ovulation, there was a mild (18-20%) reduction in ovulation efficiency. Surprisingly, galardin treatment of plg-deficient (plg-/-) mice only caused an additional 14% reduction in ovulation efficiency as compared to vehicle-treated plg-/- mice. Our data therefore suggest that although MMPs may play a role in degradation of the follicular wall, they may not be obligatory for ovulation. In contrast to previous studies on tissue remodeling during wound healing and placental development, we have demonstrated that there is no obvious functional overlap or synergy between the PA and MMP systems, which has previously been thought to be essential for the ovulatory process.

Functions for proteinases in the ovulatory process

The ovary is a unique and dynamic organ in respect to rapid and extensive degrees of tissue development and remodeling that are periodically repeated in the female reproductive activity. Ovulation is a directed and sequential process accompanied by broad-spectrum proteolysis and culminates in the follicular rupture to release the matured oocyte. This review will focus on the potential roles of six representative proteinases that are involved in various aspects of ovulatory processes: matrix metalloproteinases (MMPs), plasminogen activator (PA)/plasmin, a disintegrin and metalloproteinase domain with thrombospondin motif (ADAMTS), cathepsin-L, pregnancy-associated plasma protein-A (PAPP-A), and bone morphogenetic protein 1/mammalian Tolloid (BMP-1/mTld). Based on the studies of expression and function, these selected proteinases provide and share diverse functions ranging from cleaving components of the extracellular matrix (ECM) to modulating non-ECM molecules, such as various growth factors and their binding proteins. Consistently, the genetic deletion of each individual gene in mice shows their functional overlap in the reproductive activity.

Activity of an enzyme converting single-chain tissue-type plasminogen activator to the two-chain form in preovulatory human follicular fluid

The biological role of the tissue-type plasminogen activator (tPA)/plasmin system has long been implicated in ovarian function. We have recently shown that the follicular fluid of human ovaries contains an alpha(2)-macroglobulin/protease complex capable of converting single-chain (sc) tPA to the two-chain (tc) enzyme tPA, suggesting the occurrence of its corresponding enzyme in a free form in the fluid. The aim of the current study is therefore to gain further information about the putative sctPA-converting enzyme present in follicular fluid. Incubation of human recombinant sctPA with the fluid brought about the production of tctPA. It was also demonstrated that tctPA production resulted in the activation of endogenous fluid plasminogen. Production of tctPA and plasmin both was strongly inhibited by aprotinin, suggesting that the enzyme is a serine protease. The sctPA-converting enzyme was partially purified from the fluid by column chromatographies. The enzyme preferably hydrolyzed synthetic peptide substrates containing arginine at the P(1) position. The enzyme preparation had a protease inhibitor profile similar to that observed with the crude fluid sample. These results clearly demonstrated that follicular fluid contains an enzyme capable of efficiently converting sctPA to tctPA. Discovery of this sctPA-converting enzyme strongly suggests that the tPA/plasmin system in the preovulatory follicle of human ovaries is operated through the proteolytic conversion of sctPA to tctPA rather than being regulated by a fibrin-dependent mechanism.

Plasminogen Activator and Serine Protease Inhibitor-E2 (Protease Nexin-1) Expression by Bovine Granulosa Cells In Vitro1

Remodeling of the extracellular matrix (ECM) occurs during antral follicle growth, and the plasminogen activators (PA) have been implicated in this process in rodents. In the present study, we measured the expression and secretion of PA and the PA inhibitor protease nexin-1 (SerpinE2) in antral and basal bovine granulosa cells from small (<6 mm), medium (6-8 mm), and large follicles (>8 mm) during 6 days of culture in serum-free medium. Casein zymography revealed that the cells secreted predominantly tissue-type PA (tPA) with urokinase (uPA) being associated mainly with cell lysates, and Western blot demonstrated that the cells secreted SerpinE2. Overall, secreted tPA activity was higher in cultures of cells from small follicles compared with large follicles, and secreted SerpinE2 levels were higher in cultures of cells from large follicles. In cultures of cells from small follicles, secreted tPA levels increased with time of culture for antral but not basal cells, and SerpinE2 levels increased with time for basal but not antral cells. In cultures of granulosa cells from large follicles, tPA activity increased significantly with time of culture, whereas SerpinE2 levels decreased. Cell-associated uPA activity decreased with time in cells from medium and large follicles. Reverse-transcription polymerase chain reaction and Northern blot analysis showed that SerpinE2 secretion was regulated largely at the transcriptional level, whereas tPA secretion was not. The data suggest stage-dependent regulation of granulosa cell PA and SerpinE2 production, consistent with a role in ECM remodeling during follicle growth.

Annexin II-mediated plasmin generation activates TGF-β3 during epithelial–mesenchymal transformation in the developing avian heart

Epithelial-mesenchymal transformation (EMT), the process by which epithelial cells are converted into motile, invasive mesenchymal cells, is critical to valvulogenesis. Transforming growth factor-beta3 (TGF-beta3), an established mediator of avian atrioventricular (AV) canal EMT, is secreted as a latent complex. In vitro, plasmin-mediated proteolysis has been shown to release active TGF-betas from the latent complex. Annexin II, a co-receptor for tissue plasminogen activator (tPA) and plasminogen, promotes cell-surface generation of the serine protease plasmin. Here, we show that annexin II-mediated plasmin activity regulates release of active TGF-beta3 during chick AV canal EMT. Primary embryonic endocardial-derived cells express annexin II which promotes plasminogen activation in vitro. Incubation of heart explant cultures with either alpha(2)antiplasmin (alpha(2)AP), a major physiological plasmin inhibitor, or anti-annexin II IgG, blocked EMT by approximately 80%, and 50%, respectively. Anti-annexin II IgG-mediated inhibition of EMT was overcome by the addition of recombinant TGF-beta3. Upon treatment with anti-annexin II IgG or alpha(2)AP, conditioned medium from heart explant cultures showed absence of the active fragment of TGF-beta3 by Western blot analysis and a approximately 50% decrease in TGF-beta specific bioactivity. Our results suggest that annexin II-mediated plasmin activity regulates the release of active TGF-beta during cardiac valve development in the avian heart.

Expression pattern and functional studies of matrix degrading proteases and their inhibitors in the mouse corpus luteum

The formation of the corpus luteum (CL) is accompanied with angiogenesis and tissue remodeling and its regression involves tissue degradation. Matrix degrading proteases such as plasminogen activators (PAs) and matrix metalloproteinases (MMPs) are thought to play important roles in such controlled proteolytic processes. In this study, in situ hybridization has been used to examine the regulation and expression pattern of mRNAs coding for proteases and protease inhibitors belonging to the PA- and MMP-systems during the life cycle of the CL in an adult pseudopregnant mouse model. Of the nine proteases and five protease inhibitors that were studied, the majority were found to be temporally expressed during the formation and/or the regression of the CL. However, the mRNAs coding for urokinase type PA (uPA), membrane-type 1 MMP (MT1-MMP), and tissue inhibitor of metalloproteinases type-3 (TIMP-3) were constantly expressed in the mouse CL throughout its whole life span. To study the functional role of uPA in the CL, we analyzed luteal formation and function in uPA deficient mice. Our results revealed no significant difference in ovarian weight, serum progesterone levels, and blood vessel density in the functional CL between uPA deficient and wild type control mice. The temporal and spatial expression pattern of proteases and protease inhibitors during the CL life span suggests that members of the PA- and MMP-systems may play important roles in the angiogenesis and tissue remodeling processes during CL formation, as well as in the tissue degradation during luteal regression. However, the absence of reproductive phenotypes in mice lacking uPA and several other matrix degrading proteases indicates that there are redundancies among different matrix degrading proteases or that tissue remodeling in the ovary may involve other additional unique elements.

Leukocyte networks and ovulation

Ovulation, the process whereby the oocyte is expelled from the interior of the follicle, is the final process of folliculogenesis. During the last decade, data have accumulated to suggest that tissue-bound leukocytes are major effector cells in several physiological processes within the reproductive tract. Some specific subclasses of leukocytes seem to be critically involved in the process of ovulation. The main components of this ovulatory process are degradation of the extracellular matrix (ECM) at the follicular apex and changes in the follicular vasculature. The leukocytes participate actively in these events by secretion of proteases and vasoactive substances. This review covers our current understanding of the mechanisms by which the leukocytes are attracted to the preovulatory follicle after the LH-surge and the roles that the activated leukocytes play in the follicle during the ovulatory period.

Gonadotropin surge-induced up-regulation of the plasminogen activators (tissue plasminogen activator and urokinase plasminogen activator) and the urokinase plasminogen activator receptor within bovine periovulatory follicular and luteal tissue

This study examined the effect of the preovulatory gonadotropin surge on the temporal and spatial regulation of tissue plasminogen activator (tPA), urokinase plasminogen activator (uPA), and uPA receptor (uPAR) mRNA expression and tPA, uPA, and plasmin activity in bovine preovulatory follicles and new corpora lutea collected at approximately 0, 6, 12, 18, 24, and 48 h after a GnRH-induced gonadotropin surge. Messenger RNAs for tPA, uPA, and uPAR were increased in a temporally specific fashion within 24 h of the gonadotropin surge. Localization of tPA mRNA was primarily to the granulosal layer, whereas both uPA and uPAR mRNAs were detected in both the granulosal and thecal layers and adjacent ovarian stroma. Activity for tPA was increased in follicular fluid and the preovulatory follicle apex and base within 12 h after the gonadotropin surge. The increase in tPA activity in the follicle base was transient, whereas the increased activity in the apex was maintained through the 24 h time point. Activity for uPA increased in the follicle apex and base within 12 h of the gonadotropin surge and remained elevated. Plasmin activity in follicular fluid also increased within 12 h after the preovulatory gonadotropin surge and was greatest at 24 h. Our results indicate that mRNA expression and enzyme activity for both tPA and uPA are increased in a temporally and spatially specific manner in bovine preovulatory follicles after exposure to a gonadotropin surge. Increased plasminogen activator and plasmin activity may be a contributing factor in the mechanisms of follicular rupture in cattle.

Effect of the preovulatory LH surge on bovine follicular progesterone receptor mRNA expression

A growing body of evidence indicates that intrafollicular progesterone receptor signaling pathways are obligatory for follicle rupture. However, the intrafollicular localization and regulation of progesterone receptor expression during the periovulatory period in cattle are not known. In this study, we determined the effect of the preovulatory gonadotropin surge on localization and expression of progesterone receptor mRNA in bovine periovulatory follicular and luteal tissue. Ovaries containing preovulatory follicles or new corpora lutea (CL) were collected at approximately 0, 6, 12, 18, 24 (preovulatory follicles) and 48 h (CL) after a GnRH-induced LH surge (n=5-8 per timepoint). Expression of progesterone receptor mRNA was detected in periovulatory follicular and luteal tissue at all timepoints examined. Relative levels of progesterone receptor mRNA were dramatically upregulated within 6h after the LH surge compared to all other time points (P<0.0001). In situ hybridization analysis revealed that the significant increase in progesterone receptor mRNA expression was localized to the granulosal layer of preovulatory follicles. Our results indicate that progesterone receptor mRNA expression is upregulated specifically in the granulosal layer of bovine preovulatory follicles following the LH surge. Progesterone receptor signaling pathways may help mediate the effects of the preovulatory LH surge on follicle rupture in cattle.

Alteration in ovarian gene expression in response to 2,3,7,8-tetrachlorodibenzo-p-dioxin: reduction of cyclooxygenase-2 in the blockage of ovulation

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a reproductive toxicant and endocrine disrupter that is known to block ovulation. This study was designed to investigate alterations in relevant ovarian genes that may be involved in the blockage of ovulation by TCDD in immature intact rats primed with equine chorionic gonadotropin (eCG). In this ovulation model, rats were given either 32 microg/kg TCDD or corn oil by gavage on 25 days of age. The next day, eCG (5 IU) was injected subcutaneously (s.c.) to stimulate follicular development. Ovulation occurs 72 h after administration of eCG in controls of this model. TCDD blocked ovulation at the expected time and also reduced both ovarian and body weights. At 72 h after eCG (the morning after expected ovulation), TCDD did not alter significantly serum concentrations of progesterone (P4) and androstenedione (A4). However, estradiol (E2) was significantly higher at 72 h after eCG in TCDD-treated rats when compared with controls. Western blots revealed that ovarian CYP1A1 was induced by TCDD. In addition, the aryl hydrocarbon receptor (AhR) and AhR nuclear translocator (ARNT) were down- and up-regulated by TCDD, respectively, indicating that AhR-mediated signal transduction was altered in the ovary. Ovarian estrogen receptor (ER)alpha, ER beta and progesterone receptor (PR) were not altered significantly by TCDD, but ovarian glucocorticoid receptor (GR) was increased at 24h after TCDD and decreased at 72 h after eCG when compared with controls. TCDD induced the early appearance of ovarian plasminogen activator inhibitor type-1 (PAI-1), plasminogen activator inhibitor type-2 (PAI-2), urokinase plasminogen activator (uPA), and tissue plasminogen activator (tPA) at 24h after dosing when compared with controls. On the morning after ovulation (72 h after eCG), no significant differences between control and TCDD-treated rats were observed except that TCDD had still increased tPA and decreased PAI-2 when compared with controls. Interestingly, ovarian COX-2 was induced on the morning after ovulation (72 h after eCG) in controls, but was greatly inhibited in TCDD-treated rats at that time. On the other hand, COX-1 was constitutively expressed throughout the ovulatory period and remained unaffected by TCDD. Immunolocalization of COX-2 in the ovary revealed that TCDD inhibited COX-2 expression in the granulosa cell layer when assessed in the morning of expected ovulation. In conclusion, AhR signaling is activated in the ovary by TCDD and inhibition of COX-2 appeared to be a critical step in the TCDD blockage of ovulation because blockage or reduction of COX-2 expression is well known to be associated with failure of ovulation.

Matrix remodeling in the ovary: regulation and functional role of the plasminogen activator and matrix metalloproteinase systems

In each reproductive cycle, extensive tissue remodeling takes place in the ovary during follicular development, ovulation, formation and regression of corpus luteum (CL) and follicular atresia. Several lines of indirect evidence suggest that these changes are mediated, in part, by proteases belonging to the plasminogen activator (PA) and the matrix metalloproteinase (MMP) systems. These two enzyme systems include both proteinases and associated inhibitors, that are thought to act in concert via a cascade of proteolytic events, the end result of which is the generation of a broad spectrum proteolytic activity, that can mediate physiological tissue remodeling throughout the body. The current review highlights the key features of these two enzyme systems and focuses on their regulation and functional role during the dynamic remodeling processes that takes place in the ovary during each reproductive cycle.

Coordinate expression of anticoagulant heparan sulfate proteoglycans and serine protease inhibitors in the rat ovary: a potent system of proteolysis control

During the reproductive cycle, ovarian follicles undergo major tissue-remodeling involving vascular changes and proteolysis. Anticoagulant heparan sulfate proteoglycans (aHSPGs) are expressed by granulosa cells during the development of the ovarian follicle. The function of aHSPGs in the ovary is unknown, but they might be involved in proteolysis control through binding and activation of serine protease inhibitors. To identify functional interactions between aHSPGs and heparin-binding protease inhibitors in the follicle, we have coordinately localized aHSPGs, antithrombin III, protease nexin-1, and plasminogen activator inhibitor-1 in the rat ovary during natural and gonadotropin-stimulated cycles. Anticoagulant HSPGs were visualized by autoradiography of cryosections incubated with 125I-antithrombin III, and protease inhibitors were assessed by immunohistochemistry and Northern blot hybridization. Anticoagulant HSPGs were expressed in follicles before ovulation, were transiently decreased in postovulatory follicles, and were abundant in the corpus luteum, mainly on capillaries. Anticoagulant HSPGs were colocalized with protease nexin-1 in follicles from the early antral stage until ovulation, with antithrombin III in the preovulatory stage and after ovulation, and with plasminogen activator inhibitor-1 in the corpus luteum. These data demonstrate that aHSPGs are critically expressed in the ovary to interact sequentially with protease nexin-1, antithrombin III, and plasminogen activator inhibitor-1 during the cycle. The specificity of these inhibitors is shifted toward thrombin inhibition in the presence of heparin, suggesting that aHSPGs direct their action to control fibrin deposition in the follicle. The occupation of aHSPGs antithrombin-binding sites by mutant R393C antithrombin III, injected in the ovarian bursa, decreased ovulation efficiency, further supporting the involvement of aHSPGs in the ovulation process.

Increased expression and localization of a serine protease inhibitor, protease nexin-1 (PN-1), in the ovary and uterus during implantation in rat

Protease nexin-1 (PN-1) is a serine protease inhibitor (serpin) that inactivates several proteases, including thrombin, urokinase, plasminogen activators (PA), and plasmin. It also plays a role in regulating proteolytic activity generated by PA system. PN-1 is known to be involved in tissue remodeling, cellular invasiveness, matrix degradation, and tumor growth. However, the role of PN-1 in female reproductive tracts, such as the uterus, ovary, and oviduct, during pregnancy is not known. The present study was designed to investigate the changes of PN-1 mRNA level and localization in the tracts during implantation and early pregnancy by using reverse transcription (RT)-polymerase chain reaction (PCR) and in situ hybridization. We found that PN-1 mRNA levels were coordinately regulated during early pregnancy in a stage- and tissue-specific manner, such that an increased expression of PN-1 gene appeared at the time of the implantation period in the uterus and ovary. Both the uterus and ovary synthesized PN-1 mRNA and their maximal PN-1 expression occurred on Day 6.5 postcoitum (p.c.). On 13.5 days of pregnancy, PN-1 level was low in the uterus and ovary. On the other hand, PN-1 mRNA in the oviduct did not show after 6.5 days of pregnancy. It appears that PN-1 mRNA in the uterus and ovary was highly regulated during early pregnancy, which might have an important role in implantation of rat blastocysts. PN-1 was localized in endometrial stromal cells of the uterus and in granulosa cells of the unstimulated primary follicles in the ovary during periimplantation period. Also, PN-1 mRNA expression was higher at implantation period than that at nonimplantation period of pregnancy. In conclusion, PN-1 is expressed in female reproductive tracts and highly regulated during implantation and early pregnancy.

Plasminogen binding is increased with adipocyte differentiation

The purpose of this study was to examine the role of the plasminogen system in the development of adipose tissue. Plasminogen binding capacity was determined in differentiated and undifferentiated cells from adipose tissue of plasminogen deficient mice and 3T3 cells, a well-characterized tissue culture model. In 3T3 cells, plasminogen binding was fivefold higher in differentiated cells compared to the undifferentiated cells. Inhibition of binding by carboxyl-terminal lysine analogs was similar for the differentiated and undifferentiated cells with tranexamic acid > EACA > lysine. The binding of plasminogen was concentration-dependent and approaches saturation in the both cell types. The number of plasminogen binding sites was tenfold higher in the differentiated compared to the undifferentiated cells. In isolated mature fat cells and stromal cell cultures from mouse adipose tissue, plasminogen binding was also higher in the differentiated mature fat cells and differentiated stromal cells compared to undifferentiated stromal cells. Plasminogen binding was elevated in the differentiated cells from the Plg-/- mice compared to cells from the WT mice. These results suggest that the plasminogen system plays an important role in adipose tissue development.