Expression of plasminogen activator genes and enzymatic activities in rat preimplantation embryos

The role of endogenous tissue-type plasminogen activator in neuronal survival after ischemic stroke: friend or foe?

Endogenous protease tissue-type plasminogen activator (tPA) has highly efficient fibrinolytic activity and its recombinant variants alteplase and tenecteplase are established as highly effective thrombolytic drugs for ischemic stroke. Endogenous tPA is constituted of five functional domains through which it interacts with a variety of substrates, binding proteins and receptors, thus having enzymatic and cytokine-like effects to act on all cell types of the brain. In the past 2 decades, numerous studies have explored the clinical relevance of endogenous tPA in neurological diseases, especially in ischemic stroke. tPA is released from many cells within the brain parenchyma exposed to ischemia conditions in vitro and in vivo, which is believed to control neuronal fate. Some studies proved that tPA could induce blood-brain barrier disruption, neural excitotoxicity and inflammation, while others indicated that tPA also has anti-excitotoxic, neurotrophic and anti-apoptotic effects on neurons. Therefore, more work is needed to elucidate how tPA mediates such opposing functions that may amplify tPA from a therapeutic means into a key therapeutic target in endogenous neuroprotection after stroke. In this review, we summarize the biological characteristics and pleiotropic functions of tPA in the brain. Then we focus on possible hypotheses about why and how endogenous tPA mediates ischemic neuronal death and survival. Finally, we analyze how endogenous tPA affects neuron fate in ischemic stroke in a comprehensive view.

A novel embryo culture media supplement that improves pregnancy rates in mice

The preimplantation embryoinvivois exposed to numerous growth factors in the female reproductive tract, which are not recapitulated in embryo culture mediain vitro. The IGF2 and plasminogen activator systems facilitate blastocyst development. We hypothesized that the addition of IGF2 in combination with urokinase plasminogen activator (uPA) and plasminogen could improve rates of blastocyst hatching and implantation in mice. B6BcF1 and CBAB6F2 mouse embryos were divided into one of four supplemented culture media treatment groups: (1) control (media only); (2) 12.5 nM IGF2; (3) 10 µg/mL uPA and 5 µg/mL plasminogen; or (4) a combination of IGF2, uPA and plasminogen treatments. Embryo development to blastocyst stage and hatching were assessed before transfer to pseudopregnant recipient females and implantation, pregnancy rates and postnatal growth were assessed. After 90.5 h of culture, IGF2 + U + P treatment increased the percentage of B6BcF1 embryos that were hatching/hatched and percentage developing to blastocyst stage compared with controls (P < 0.02). Following B6BcF1 embryo transfer, IGF2 + U + P treatment increased implantation sites at day 8 of pregnancy compared with controls (P < 0.05). Replication in the CBAB6F2 mouse strain showed significant improvements in pregnancy rates at days 8 and 18 but not in blastocyst development. No adverse effects were seen on gestational age, litter size or birthweight, or the reproductive capacity of offspring of IGF2 + U + P treated embryos. For embryos susceptible to detrimental effects ofin vitroculture, IGF2, uPA and plasminogen supplementation of culture media can improve pregnancy success, but the effect of treatment is dependent on the mouse strain.

Effects of Fluoxetine on Human Embryo Development

The use of antidepressant treatment during pregnancy is increasing, and selective serotonin reuptake inhibitors (SSRIs) are the most widely prescribed antidepressants in pregnant women. Serotonin plays a role in embryogenesis, and serotonin transporters are expressed in two-cell mouse embryos. Thus, the aim of the present study was to evaluate whether fluoxetine, one of the most prescribed SSRI antidepressant world-wide, exposure influences the timing of different embryo developmental stages, and furthermore, to analyze what protein, and protein networks, are affected by fluoxetine in the early embryo development. Human embryos (n = 48) were randomly assigned to treatment with 0.25 or 0.5 μM fluoxetine in culture medium. Embryo development was evaluated by time-lapse monitoring. The fluoxetine-induced human embryo proteome was analyzed by shotgun mass spectrometry. Protein secretion from fluoxetine-exposed human embryos was analyzed by use of high-multiplex immunoassay. The lower dose of fluoxetine had no influence on embryo development. A trend toward reduced time between thawing and start of cavitation was noted in embryos treated with 0.5 μM fluoxetine (p = 0.065). Protein analysis by shotgun mass spectrometry detected 45 proteins that were uniquely expressed in fluoxetine-treated embryos. These proteins are involved in cell growth, survival, proliferation, and inflammatory response. Culturing with 0.5 μM, but not 0.25 μM fluoxetine, caused a significant increase in urokinase-type plasminogen activator (uPA) in the culture medium. In conclusion, fluoxetine has marginal effects on the timing of developmental stages in embryos, but induces expression and secretion of several proteins in a manner that depends on dose. For these reasons, and in line with current guidelines, the lowest possible dose of SSRI should be used in pregnant women who need to continue treatment.

Expression and localization of urokinase-type plasminogen activator receptor in bovine cumulus–oocyte complexes

Urokinase-type plasminogen activator (uPA) is a serine protease involved in extracellular matrix remodeling through plasmin generation. uPA usually binds to its receptor, uPAR, which is anchored to the plasma membrane through a glycosylphosphatidylinositol anchor. uPA/uPAR binding increases proteolytic activity in the neighborhood of the cells containing uPAR and activates intracellular signaling pathways involved in extracellular matrix remodeling, cell migration and proliferation. The aim of this work was to study the expression of uPA, uPAR and plasminogen activator inhibitor-1 (PAI-1) in immature and in vitro matured bovine cumulus–oocyte complexes (COCs). uPA is only expressed in the cumulus cells of immature and in vitro matured COCs, while uPAR and PAI-1 are expressed in both the cumulus cells and the immature and in vitro matured oocytes. In addition, uPAR protein was localized by confocal microscopy in the plasma membrane of oocytes and cumulus cells of immature COCs. Results from this research led us to hypothesize that the uPA/uPAR interaction could cause the local production of uPA-mediated plasmin over oocyte and cumulus cell surface; plasmin formation could also be regulated by PAI-1.

Serglycin proteoglycan deletion in mouse platelets: physiological effects and their implications for platelet contributions to thrombosis, inflammation, atherosclerosis, and metastasis

Serglycin is found in all nucleated hematopoietic cells and platelets, blood vessels, various reproductive and developmental tissues, and in chondrocytes. The serglycin knockout mouse has demonstrated that this proteoglycan is required for proper generation and function of secretory granules in several hematopoietic cells. The effects on platelets are profound, and include diminishing platelet aggregation responses and formation of platelet thrombi. This chapter will review cell-specific aspects of serglycin structure, its gene regulation, cell and tissue localization, and the effects of serglycin deletion on hematopoietic cell granule structure and function. The effects of serglycin knockout on platelets are described and discussed in detail. Rationales for further investigations into the contribution of serglycin to the known roles of platelets in thrombosis, inflammation, atherosclerosis, and tumor metastasis are presented.

Testosterone upregulation of tissue type plasminogen activator expression in Sertoli cells : tPA expression in Sertoli cells

Our previous studies have demonstrated that tissue type plasminogen activator (tPA) might be involved in matrix degradation of blood-testis barrier in rat. In this study, we have further investigated the effect of testosterone (T) on tPA production in rat Sertoli cells. Our results showed that Sertoli cells isolated from rat testes at various ages in vitro secreted tPA in an age-dependent manner. The tPA activity was detected on day 20 after birth, and reached maximum on day 60. The Sertoli cells isolated from the testes on day 20 were then cultured in the presence or absence of testosterone, FSH, and forskolin, the tPA activities were upregulated by T, FSH and forskolin. Addition of H89 or U0126, both inhibited the testosterone-, FSH-, and forskolin-induced tPA expression. It is suggested that FSH- and testosterone-stimulated tPA expression in Sertoli cells may be via PKA and ERK signal transduction. Furthermore, we have observed that testosterone stimulated tPA secretion at all the stages of spermatogenesis (II-VI, VII-VIII, IX-XII and XIII-I), the highest stimulation of tPA activity was observed at stages VII-VIII. This study further suggests that testosterone-induced tPA activity in the Sertoli cells might be related to the function of blood-testis barrier opening and/or closing.

EGF increases expression and activity of PAs in preimplantation rat embryos and their implantation rate

BACKGROUND

Embryo implantation plays a major role in embryogenesis and the outcome of pregnancy. Plasminogen activators (PAs) have been implicated in mammalian fertilization, early stages of development and embryo implantation. As in-vitro developing embryos resulted in lower implantation rate than those developed in-vivo we assume that a reduced PAs activity may be involved. In the present work we studied the effect of EGF on PAs activity, quantity and embryo implantation.

METHODS

Zygotes were flushed from rat oviducts on day one of pregnancy and grown in-vitro in R1ECM supplemented with EGF (10 ng/ml) and were grown up to the blastocyst stage. The control groups were grown in the same medium without EGF. The distribution and quantity of the PAs were examined using fluorescence immunohistochemistry followed by measurement of PAs activity using the chromogenic assay. Implantation rate was studied using the embryo donation model.

RESULTS

PAs distribution in the embryos was the same in EGF treated and untreated embryos. Both PAs were localized in the blastocysts' trophectoderm, supporting the assumption that PAs play a role in the implantation process in rats.EGF increased the quantity of uPA at all stages studied but the 8-cell stage as compared with controls. The tissue type PA (tPA) content was unaffected except the 8-cell stage, which was increased. The activity of uPA increased gradually towards the blastocyst stage and more so due to the presence of EGF. The activity of tPA did not vary with the advancing developmental stages although it was also increased by EGF. The presence of EGF during the preimplantation development doubled the rate of implantation of the treated group as compared with controls.

Comparison of real-time polymerase chain reaction and end-point polymerase chain reaction for the analysis of gene expression in preimplantation embryos

The aim of the present study was to compare real-time polymerase chain reaction (PCR) and end-point PCR with respect to their suitability for the analysis of gene expression in samples in which the number of cells is limited; for example, in studies of preimplantation embryonic development and to determine the variability of the real-time reverse transcription-PCR assay. The sensitivity, dynamic range and precision of both PCR systems were compared using a single mouse liver cDNA standard. The real-time system was 100-fold more sensitive than the end-point system and had a dynamic range of more than four orders of magnitude. The linear range for end-point PCR extended for two orders of magnitude using a fixed end-point of 31 cycles. The percentage standard error of the mean based on 30 replicates was 0.14% of the threshold cycle (Ct) value for the real-time system and 6.8% for the end-point fluorescence intensity. The coefficients of variation (CV) for reverse transcription combined with real-time analysis and the complete gene expression protocol consisting of mRNA isolation, reverse transcription and real-time PCR analysis were 0.6% and 1.4% of the Ct values, respectively. The present paper details, for the first time, measurement of the biological variation of individual mammalian oocytes. The CV was 1.8% of the Ct value for expression analysis of six bovine oocytes. The results are discussed in relation to the analysis of gene expression in preimplantation embryo development.

Effects of plasmin on sperm-oocyte interactions during in vitro fertilization in the pig

The present study was undertaken to examine the effect of plasmin on sperm viability and sperm-oocyte interaction during in vitro fertilization in the pig. Porcine sperm, which were washed in Dulbecco's PBS were re-suspended and incubated in fertilization medium (mTBM; modified Tris-buffered medium) containing 0, 0.1, 1.0, 10.0 or 100.0ng/mL of plasmin. Sperm viability was not affected by plasmin treatment. Addition of plasmin in doses ranging from 0.1 to 100.0ng/mL for 2, 4 or 6h to washed boar sperm resulted in enhancement of acrosome reaction (AR) compared with untreated cells. The concentration of 0.1ng/mL plasmin (95+/-18 sperm/oocyte) had no effect on sperm binding, whereas 1.0ng/mL (123+/-21 sperm/oocyte), 10.0ng/mL (124+/-16 sperm/oocyte) and 100.0ng/mL (124+/-15 sperm/oocyte) of plasmin increased sperm binding compared with the control (83+/-15 sperm/oocyte). The zona pellucida solubility (zona dissolution time) was less in medium with 1.0ng/mL (123+/-24s), 10.0ng/mL (99+/-15s) or 100.0ng/mL (95+/-19s) plasmin compared with control (176+/-27s). When pig oocytes and sperm were co-incubated in various concentrations of plasmin for 6h, the penetration rate was greater in medium with 1.0ng/mL plasmin (77.5+/-3.1%) compared with the control. However, there were no differences in the polyspermic rates and mean number of sperm (MNS)/oocyte between the groups treated with plasmin and control. These results suggest that plasmin might play a role in events related to fertilization.

Selection of reference genes for quantitative real-time PCR in bovine preimplantation embryos

Background

Real-time quantitative PCR is a sensitive and very efficient technique to examine gene transcription patterns in preimplantation embryos, in order to gain information about embryo development and to optimize assisted reproductive technologies. Critical to the succesful application of real-time PCR is careful assay design, reaction optimization and validation to maximize sensitivity and accuracy. In most of the studies published GAPD, ACTB or 18S rRNA have been used as a single reference gene without prior verification of their expression stability. Normalization of the data using unstable controls can result in erroneous conclusions, especially when only one reference gene is used.

Results

In this study the transcription levels of 8 commonly used reference genes (ACTB, GAPD, Histone H2A, TBP, HPRT1, SDHA, YWHAZ and 18S rRNA) were determined at different preimplantation stages (2-cell, 8-cell, blastocyst and hatched blastocyst) in order to select the most stable genes to normalize quantitative data within different preimplantation embryo stages.

Conclusion

Using the geNorm application YWHAZ, GAPD and SDHA were found to be the most stable genes across the examined embryonic stages, while the commonly used ACTB was shown to be highly regulated. We recommend the use of the geometric mean of those 3 reference genes as an accurate normalization factor, which allows small expression differences to be reliably measured.

Expression of plasminogen activators in preimplantation rat embryos developed in vivo and in vitro

BACKGROUND

Embryo implantation plays a major role in embryogenesis and the outcome of pregnancy. Plasminogen activators (PAs) have been implicated in mammalian fertilization, early stages of development and embryo implantation. The invasion of trophoblast cells into the endometrium during the implantation process can be blocked by inhibitors of serine proteases, illustrating the role of these enzymes in the invasion process. As in vitro developing embryos resulted in lower implantation rate than those developed in vivo we assume that a reduced PAs activity may lead to it. There is hardly any information regarding qualitative or quantitative differences in expression of PAs in preimplantation embryos, or comparisons between in vivo and in vitro developed embryos. The purpose of this study was to assess the expression of urokinase type (uPA) and tissue type (tPA) plasminogen activators in in vivo and in vitro preimplantation development in rat embryos using immunofluorescence confocal microscopy and computerized image analysis.

METHODS

Zygotes, 2-cell, 4-cell, 8-cell, morula and blastocyst stages of development were flushed from the reproductive tract (control groups) of Wistar rats. Zygotes were flushed and grown in vitro to the above mentioned developmental stages and comprised the experimental groups. Immunofluorescence microscopy and computerized image analysis were used to evaluate both qualitative (localization) and quantitative expression of plasminogen activators.

RESULTS

uPA and tPA were found to be expressed in rat embryos throughout their preimplantation development, both in vivo and in vitro. While uPA was localized mainly in the cell cytoplasm, the tPA was detected mainly on cell surface and in the perivitelline space. In blastocysts, both in vivo and in vitro, uPA and tPA were localized in the trophectoderm cells. Total uPA content per embryo was higher in the in vivo as compared with the in vitro developed embryos at all stages measured. Blastocyst uPA content was significantly low as compared with the four-cell, eight-cell, and morula stages. Total tPA content was higher in embryos developed in vivo than those developed in vitro except for the 4-cell and 8-cell stages.

CONCLUSION

In vitro embryo development leads to lower PAs expression in a stage dependent manner as compared with in vivo developing controls. The enzymes studied vary probably in the ratio of their active and inactive forms as there is no correlation between their content and the activity observed in our previous study. The localization of both PAs in the blastocysts' trophectoderm supports the assumption that PAs plays a role in the implantation process in rats.

Differences in the implantation rates of rat embryos developed in vivo and in vitro: possible role for plasminogen activators

OBJECTIVE

To assess the participation of urokinase-type (uPA) and tissue-type (tPA) plasminogen activators in embryo development and implantation.

DESIGN

The study was set to compare the activities of PAs in embryos developed in vivo and in vitro and their implantation rates. Endometrial PA activity was studied as well.

SETTING

University laboratories.

PATIENT(S)

None.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Plasminogen activator activity in embryos.

RESULT(S)

Whereas tPA activity in in vivo-developed embryos decreased from the zygote to the blastocyst stages, it did not change in embryos developed in vitro. The activity of uPA was lowest in two-cell-stage embryos, both in vivo and in vitro, and increased as embryos developed into blastocysts. The activity of uPA in the in vitro-developed embroys was lower in all developmental stages as compared with those developed in vivo. Whereas endometrial tPA activity did not change during the preimplantation period, uPA activity increased gradually toward the time of implantation. The implantation rate of the in vitro-developed embryos was much lower than that of those developed in vivo.

CONCLUSION(S)

Taken together, these data indicate that in vitro embryo development leads to lower PA activities as compared with in vivo development. The increased activity of uPA toward the blastocyst stage supports uPA's role in the implantation process. Moreover, the rise in endometrial uPA might also indicate its importance in this process.

Role of plasminogen activators during healing after uterine serosal lesioning in the rat

OBJECTIVE

Study the expression pattern of tissue-type (t-PA) and urokinase-type (u-PA) plasminogen activators during uterine serosal healing after lesioning in a rat model.

DESIGN

Descriptive study with an adhesion model using reverse transcriptase-polymerase chain reaction (PCR) and immuncytochemical techniques.

SETTING

Academic medical center.

PATIENT(S)

None.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Expression profiles of t-PA and u-PA were examined in the uteroperitoneal adhesion tissues of rat from the time of injury until day 7 after surgery using relative abundance reverse transcriptase-PCR and immunocytochemical techniques.

RESULT(S)

The t-PA transcript levels dropped in uteroperitoneal tissues by 6 hours after surgery and remained low until day 5. Thereafter, a rapid up-regulation of this transcript was observed at day 7. In contrast, the u-PA transcript levels demonstrated a biphasic profile during the progression of adhesion development with peaks at 2 and 5 days after surgery. Immunocytochemical staining demonstrated expression of these plasminogen activators in the newly formed blood vessels.

CONCLUSION(S)

Altered levels of t-PA and u-PA transcripts and its expression in newly formed blood vessels during healing and adhesion development indicate involvement of these plasminogen activators in serosal healing and adhesion development.

Quantification of housekeeping transcript levels during the development of bovine preimplantation embryos

In mammals, the study of gene expression in the preimplantation embryo has been difficult because the standard procedures used to quantify mRNA generally require large amounts of starting material. The development of protocols using different quantitative strategies generally involving the polymerase chain reaction (PCR) has provided new tools for exploration of gene expression in preimplantation embryos. However, the use of an internal standard, often referred as a housekeeping gene, is essential to normalize the mRNA levels. RNA levels of eight housekeeping genes were quantified using real time PCR throughout the preimplantation period of the bovine embryo to find the most suitable gene to be used as standard. Histone H2a was the best internal standard because the transcript levels were constant across the preimplantation period. Linear amplification of antisense RNA using the T7 promotor for in vitro transcription of the entire RNA pool was evaluated as a suitable way to preamplify the starting material prior to quantification and was effective in providing accurate RNA abundance profiles throughout the preimplantation period. However, the amplification appears to be template dependent because the amplification factors were higher for some genes.

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.

Effects of leukaemia inhibitory factor on embryo implantation in the mouse

Leukaemia inhibitory factor (LIF) is a pleiotrophic cytokine. Recent reports indicate that LIF is relevant to murine embryo implantation. In this work, results of indirect immunofluorescence under a confocal microscope illustrated that LIF was mainly located in the uterine lumen and uterine epithelial cells in pregnant mice on day 4. The number of embryos implanted in pregnant mice on day 8 decreased significantly after injection of 3 microg LIF antibodies into a uterine horn (P<0.001), which demonstrated again that LIF is a critical factor for embryo implantation. In a co-culture system, LIF (0.1 ng/ml, 1 ng/ml, 10 ng/ml and 100 ng/ml) significantly enhanced the blastocyst outgrowth after 24, 48 or 72 h of co-culture, and outgrowth areas after 72 h of co-culture. Conversely, 5 microg/ml and 10 microg/ml, but not 1 microg/ml, LIF antibodies decreased the percentage of blastocysts with outgrowth; only 10 microg/ml LIF antibody inhibited blastocyst outgrowth area significantly (P<0.001). However, neither LIF nor its antibodies changed embryo attachment. Analysis of correlation showed that the effects of LIF or its antibodies on the blastocyst outgrowth were dose-dependent. In summary, different pathways may exist to regulate the blastocyst attachment and outgrowth on a monolayer of uterine epithelial cells. LIF protein from the maternal uterus exerts an essential role in embryo implantation in the mouse, which is mediated by stimulating trophoblast outgrowth, but not by promoting the attachment.

Oviductal plasminogen activator inhibitor-1 (PAI-1): mRNA, protein, and hormonal regulation during the estrous cycle and early pregnancy in the pig

Recent identification of plasminogen activator inhibitor-1 (PAI-1) in the pig oviduct has prompted an evaluation of its mRNA, protein synthesis, and hormonal regulation during the estrous cycle and early pregnancy, defined as time prior to and after maternal recognition of pregnancy. To examine PAI-1 protein synthesis, oviductal tissue was collected from European Large White and Chinese Meishan gilts on days 0, 2, and 5 of early pregnancy, divided into three functional segments, and cultured. Culture media was collected and de novo synthesized PAI-1 analyzed by 2D-SDS-PAGE, fluorography, and densitometry. To determine hormonal regulation of PAI-1 synthesis and secretion, four groups of ovariectomized (OVX) cross-bred gilts were each treated with one of four steroid regimens (corn oil, estrogen, progesterone, or estrogen + progesterone) and tissue collected for RNA or cultured. Steady-state mRNA levels of PAI-1 were evaluated throughout the estrous cycle in cross-bred gilts. To compare steady-state PAI-1 mRNA levels between cyclic and pregnant cross-bred gilts, tissue was collected on days 0, 2, and 12. Quantitative analysis of steady-state levels of PAI-1 mRNA were analyzed by dot-blot hybridization and densitometry. A greater (P < 0.01) synthesis and secretion of PAI-1 protein was found in the isthmus portion of the oviduct relative to either the ampulla or infundibulum regardless of day of pregnancy or breed. No difference could be detected for PAI-1 protein between breeds. The Large White had a greater (P < 0.05) secretion of PAI-1 on day 2 of early pregnancy relative to other days examined. Whole oviductal tissue from cross-bred gilts was found to have a significantly greater amount of PAI-1 mRNA on days 1 and 2 compared to other days examined, while the isthmus had significantly greater levels of mRNA on days 2 and 12. A significant effect of day and segment was detected for levels of PAI-1 mRNA from cyclic and early pregnant cross-bred gilts. PAI-1 mRNA was found to be significantly greater in the isthmus than other segments, regardless of day of the estrous cycle or pregnancy. An interaction was detected for estrogen and progesterone on PAI-1 mRNA (P < 0.05) and protein (P = 0.09). Estrogen was found to inhibit PAI-1 protein synthesis and also inhibited progesterone-mediated stimulation of PAI-1 mRNA. Our results demonstrate expression of PAI-1 mRNA and protein are highest on day 2 of early pregnancy, which is consistent with its proposed function of protecting the oocyte/embryo from enzymatic degradation and/or extracellular matrix remodeling of both oviduct and early cleavage-stage embryo.

Identification and localization of plasminogen activator inhibitor-1 within the porcine oviduct

The porcine oviduct synthesizes de novo and secretes a number of proteins into culture medium, many of which are unidentified. The objectives of the present study were to 1) semipurify and identify a M(r) 45 000 secreted protein of the oviduct, 2) examine its synthesis within the three functional segments (infundibulum, ampulla, and isthmus), and 3) evaluate its distribution throughout the oviduct. Oviductal tissue was collected during early pregnancy, divided into functional segments, and subsequently cultured. Medium was collected, and the M(r) 45 000 protein was concentrated by gel-filtration chromatography. The semipurified protein was transferred onto a polyvinylidene fluoride membrane and subjected to N-terminal amino acid analysis. The 26-amino acid sequence was 96% identical to that of pig plasminogen activator inhibitor (PAI)-1. Analysis by 1-dimensional SDS-PAGE and fluorography of rabbit anti-human PAI-1-immunoprecipitated product confirmed PAI-1. Subsequent 2-dimensional SDS-PAGE and fluorographic analyses of media revealed greater PAI-1 synthesis by the isthmus than by the ampulla or infundibulum. PAI-1 was immunolocalized throughout the oviduct and was heavily concentrated in the apical region of epithelial cells. Immunogold electron microscopy localized PAI-1 within putative secretory granules in the epithelial apical region and also associated with cilia in the isthmus. Isthmic PAI expression suggests a crucial role in protecting the preimplantation embryo from proteolytic degradation as well as in regulation of extracellular matrix turnover and remodeling.

Gelatinases A and B and tissue inhibitors of metalloproteinases 1, 2, and 3 during in vivo and in vitro decidualization of rat endometrial stromal cells

An important event during decidualization is the remodeling of the extracellular matrix, an event controlled by the balance of matrix metalloproteinases and tissue inhibitors of metalloproteinases (TIMPs). A putative regulator of decidualization is prostaglandin E2 (PGE2). The present study shows that endometrial mRNA levels for TIMPs 1, 2, and 3 were increased while gelatinase A levels remained unchanged and gelatinase B levels decreased during oil-induced decidualization. The production of TIMPs 1, 2, and 3 and gelatinases A and B during in vitro decidualization was examined, as was the role of PGE2 as a regulator. Ovariectomized rats were given a regimen of estrogen and progesterone, which sensitized their uteri for decidualization, at which time endometrial stromal cells were isolated and cultured in serum-free conditions for 72 h. Northern blot analyses indicated the presence of the mRNAs for TIMPs and gelatinases, while reverse zymography and zymography showed the presence of their proteins. PGE2 decreased mRNA levels for TIMP-1 and gelatinase A but had no effect on gelatinase B or TIMPs 2 and 3. Indomethacin had no effect on any of the transcripts. These data indicate that rat endometrial stromal cells undergoing decidualization in vitro secrete gelatinases and TIMPs, and suggest that PGE2 may play a role in regulating tissue remodeling during decidualization.

Recent advances in assisted reproductive technologies

Assisted reproductive technologies (ART) have received considerable attention, both clinically and empirically. Drs. Steptoe and Edwards removed one oocyte surgically from a woman with infertility related to tubal disease. They fertilized this oocyte in vitro and transferred the formed embryo to the woman's uterus and achieved pregnancy and delivery. The technique of in vitro fertilization (IVF) and embryo transfer (ET) quickly became widely utilized for other causes of infertility as well as for tubal disease. In the last 5 years there has been a number of new developments that are reviewed in this article. The most important and now widely practiced technology has been direct intracytoplasmic injection (ICSI) of the husband's sperm into the wife's oocyte. This was developed for treatment of infertility related to low sperm count. Subsequently it was shown that sperm can be aspirated from epididymis or found in testicular biopsy in obstructive azoospermia. Another promising development is in vitro maturation (IVM) of immature oocytes. This has the potential of avoiding ovarian hyperstimulation, which can be uncomfortable and occasionally dangerous. Some oocytes are unable to fertilize and/or develop into normal embryos. It may be possible that the problem is with the machinery of cytoplasm of the oocyte. Therefore cytoplasmic transfer from a normal oocyte to an abnormal oocyte may overcome the problem. Infertile couples may be faced with many psychological problems that become even more complex with various treatments. Whereas donation of oocytes or embryos can be technically quite simple, there are many psychological issues involved. As can be gathered from aforementioned discussions, the treatments developed for infertility appear to be somewhat illogical and in the style of "shot gun therapy." In the field of infertility, as in other areas of medicine, it is of paramount importance to know the details of disease mechanisms. This in turn will allow specific and logical treatments to be developed.

Proteinase expression in early mouse embryos is regulated by leukaemia inhibitory factor and epidermal growth factor

Several proteinases from different multigene families have been implicated in the uterine invasion required for establishment of pregnancy in some mammals. In this study, the expression of matrix metalloproteinase gelatinase B (MMP-9), urokinase-type plasminogen activator (uPA) and their inhibitors was investigated during early mouse embryo development. Transcripts for tissue inhibitors of metalloproteinases (TIMP-1,-2,-3) and uPA receptor were detected throughout pre- and peri-implantation development whilst MMP-9 and uPA mRNAs were first detected in peri-implantation blastocysts associated with the invasive phase of implantation. Through use of in situ hybridization, it was shown that MMP-9 transcripts were strongly expressed in the network of trophoblast giant cells at the periphery of implanting 7.5 day embryos and TIMP-3 transcripts were strongly expressed in the decidua immediately adjacent to the implanting embryo. uPA transcripts were preferentially expressed in the ectoplacental cone and its derivatives. Because these proteinases are regulated by growth factors and cytokines in other tissues, the effect of leukaemia inhibitory factor (LIF) and epidermal growth factor (EGF) on their activity was investigated. Both LIF and EGF, like the proteinases, have been implicated in peri-implantation development. Blastocysts collected on day 4 of pregnancy were cultured 2 days in TCM 199 + 10% fetal bovine serum to allow outgrowth followed by 24 hour culture in defined media containing either LIF or EGF. Conditioned media were assayed for uPA activity by a chromogenic assay and MMP activity by gelatin zymography. Both LIF and EGF stimulated uPA and MMP-9 activity in blastocyst outgrowths after 3 days of culture (day 7). Proteinase activity was assayed again at the 5th to 6th day of culture (day 9 to 10). EGF was found to have no effect whereas LIF decreased production of both proteinases. These results demonstrate that proteinase activity in early embryos can be regulated by growth factors and cytokines during the implantation process and, in particular, they demonstrate the possible involvement of LIF in establishment of the correct temporal programme of proteinase expression.